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University of Medicine and Pharmacy Tirgu-Mures

Course of Interventional Cardiology

Authors:

Benedek Theodora and Benedek Imre

2013 This book is for educational purposes only, to be used by the medical students

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Table of contents

1. Introduction..3

2. Historic perspectives3

3. The structure of a laboratory of interventional cardiology .6

4. Cardiac catheterization**.8

5. Coronary angiography**23

6. Percutaneous coronary interventions..35

7. Imaging in interventional cardiology..46

8. Structural interventions....59

9. Interventional treatment in peripheral arterial diseases...72

10. Interventional treatment in aortic aneurysms.81

11. Interventional treatment in carotid artery diseases...83

12. Interventional treatment in renal artery stenosis.85

13. Renal denervation in severe hypertension..87

14. Interventional electrophysiology88

15. Interventional therapy in heart failure96

References.98

*This book includes a selection of the most relevant and recent publications and guidelines in the field of interventional cardiology, together with original texts of the authors. **by permission of Oxford University Press

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1. Introduction

The goal of this book is to provide the necessary knowledge to

become familiar with invasive techniques used in cardiology for

interventional diagnosis and treatment of different heart diseases.

Therapeutic decisions in cardiology are crucially determined by

invasive imaging of coronary arteries and haemodynamics, which are

essential for understanding the pathophysiological and diagnostic aspects of

cardiovascular disease.

2. Historic perspectives

The first catheterization in animals was performed by Charles Bernard

in 1846, and the first measurement of intracardiac pressures in animals by

Chauveau and Marey in 1861.

The first right heart catheterization as self-experiment was performed

by Forssmann in 1929 followed by the first clinically used cardiac

catheterization performed in 1930 by Klein.

Cournard and Marurice initiated the routine clinical use of cardiac

catheterization therapy in 1939 and since than, cardiac catheterization it

rapidly became one of the most commonly performed medical techniques in

cardiology.

After first clinical application of cardiac catheterization procedures in

the period of 1938-1948, left heart access was first tempted in the ages of

`50. The period of 1960-1977 was characterized by large scale spread of

coronary angiography procedures, and since 1977 a rapid development of

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different therapeutic procedures is encountered, with applications in

different fields of cardiology (ischaemic heart diseases, valvular heart

diseases, congenital heart diseases, electrophysiology, structural

interventions, etc) so that in present almost the full spectrum of heart

diseases is covered by applications of interventional cardiology.

Different cornerstones have been recorded during the years, like:

-1942 - catheterization of right venbtrile by Cournard and Maurice

-1944 - catheterization of pulmonary artery by Cournard and Maurice

-1949 - regtrograde catheterization by Zimmerman

-1956 - first apical left ventricular puncture by Brock

-1959 - first transseptal left atrial access by Ross

-1970 - Bedside catheterization and monitoring of right heart pressures by

Ganz and Swan

The pioneer of therapeutic interventional cardiology was Andreas

Grunzig, who performed the first Percutaneous Transluminal Coronary

Angioplasty (PTCA) in 1977. From 1977 to 1981, coronary angioplasty was

recommended for only selected cases, in symptomatic patients with good

ventricular function. However, since the `80s an impressive spread of the

indications of coronary angioplasty has been recorded, after new

technological advances such as steerable guidewires and monorail catheters

had made PTCA easier and more successful.

The concept of directional atherectomy was introduced by Simpson in

1985 and the first atherectomy was performed in 1987 in femoral superficial

artery.

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As the restenosis remained the main limitation of coronary

angioplasty, new devices have been developed to overcome the potential risk

of neointimal proliferation, such as brachyterapy in 1996. However, the

main and revolutionary development in interventional cardiology is

represented by introduction of coronary stenting, which brought a solution to

the main problem of restenosis. The first coronary stenting was performed in

1986 by Puel, and initially it was recommended only for treatment of

coronary occlusions during PCI. In 1991, Serruys reported a re-stenosis rate

of 14%, much below the one recorded by PTCA alone. The risk of stent

thrombosis was overcomed after initiation of dual antiplatelet therapy as

adjuvant.

As the restenosis of implanted stents remained a critical issue, during

the last years of the 21th century a large number of drug-eluting stent (DES)

types have been proposed to prevent restenosis (Cypher, Taxus, etc). Over

the following years, many new generations DES have been introduced in the

interventional cardiology market leading to achievement of very low

resetenosis rates nowadays. Since 2005, new generations of biodegradable

stents have also bee introduced on the market

The latest years are dominated by an impressive expansion of new

imaging techniques in interventional cardiology: Intravascular Ultrasound

associated with Virtual Histology, allowing complex assessment of the

morphology of coronary plaques based on the echo-attenuations of plaques,

Optical Coherence Tomography, allowing intracoronary visualization of

coronary plaques, accurate assessment of intima and superb visualization of

intracoronary thrombus, or Near-infrared spectroscopy (NIR), characterizing

the plaque composition according to its cholesterol content.

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3. The structure of a laboratory of interventional cardiology

A laboratory of interventional cardiology contains a special X-ray

equipment called angiograph, consisting in an X-ray tube and a generator of

X-ray source. The tub of the angiograph has a mobile component, allowing

rotation and tilting in order to provide visualization of coronary tree from

different angles, which is crucial for accurate assessment of coronary artery

stenoses. Also, the angiograph is equipped with monitors on which coronary

arteries are visualized after injection of contrast material in the coronary

ostium.

Usually images and cineloops are saved on dedicated workstations of

on storage devices.

The injection of high volumes of contrast material (necessary in case

of ventriculography, aortography or arteriography) is usually performed

using contrast injectors with adjustable presetings of speed and volume.

All the interventional laboratories should be equipped with the

necessary devices for cardio-pulmonary resuscitation or other types of

emergencies (defibrillators, temporary pacemaker, monitors, ECG, etc),

while in a complex laboratory of interventional cardiology more complex

equipments should be present, such as contrapulsation pump, intravascular

ultrasound, etc.

In case of a laboratory dedicated to electrophysiology procedures, it

contains also special equipments (EP lab systems, stimulators and devices

for ablation of cardiac arrhythmia)

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Fig. 1 - structure of a cardiac catheterization laboratory

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4. Cardiac catheterization

Cardiac catheterization represents introduction of special catheters in

the heart chambers, allowing hemodynamic measurements in the heart

cavities (pressure, gradients, shunts). Invasive assessment of cardiac

haemodynamics and coronary physiology and imaging needs temporary

vascular access, which is realized using arterial puncture (usually femoral or

radial). The femoral approach is the most used currently, however the radial

approach is gaining in popularity and acceptance. Similarly, venous

puncture (femoral, brachial, internal jugular vein, subclavian) is currently

used to access the right heart (or the left heart through trans-septal puncture).

The term right heart catheterization refers to catheterization of right

cardiac chambers, performed using venous femoral approach, by puncturing

either left or right femoral vein, while left heart catheterization means

catheterization of left cardiac chambers performed using arterial approach,

puncturing right or left femoral artery (fig.2).

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Fig. 2 - Right and left cardiac approach

Indications:

The main indications for cardiac catheterization are the following,

when these data cannot be ontained non-invasively.

-assesment of valvulopathy severity

-determination of cardiac output

-determination of intracardiac shunts

-determination of pulmonary artery pressure and pulmonary capilary

wedge pressure

-determination of Left ventricular end-diastolic pressure indicator of

LV dysfunction severity

-determination of pulmonary and systemic vascular resistences

-asesment of reversibility degree of pulmonary hypertension.

Right heart catheterisation

Following local anaesthesia, the femoral vein is punctured before the

common femoral artery is catheterized, and the sheath introduced by the

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Seldinger technique. Using a 6F SwanGanz catheter allows a mostly easy

passage to the pulmonary artery with low risk of injury to the right-heart

chambers (fig.3).

To advance the catheter from the femoral vein to the pulmonary artery,

the tip of the catheter is advanced from the lower right atrium by clockwise

rotation over the tricuspid orifice, and then advanced into the right ventricle.

To reach the pulmonary artery, the catheter must be slightly withdrawn so

that its tip lies horizontally and just to the left of the spine. Clockwise

rotation then causes the tip of the catheter to point upwards towards the right

ventricular outflow tract. The catheter should only be advanced when it is in

this position in order to minimize the risk of arrhythmia and injury to the

right ventricular wall. If these manoeuvres fail to gain access to the

pulmonary artery due to enlarged right-heart chambers, the catheter may be

withdrawn to the right atrium and formed into a large reverse loop by

catching the tip in a hepatic vein and advancing the catheter quickly into the

right atrium. This allows the tip of the catheter to advance through the

tricuspid valve in an upward position. The catheter should then cross the

pulmonary valve and advance to a pulmonary wedge position without

difficulty. If the pulmonary valve cannot be passed, a guidewire can be

employed to facilitate positioning in the pulmonary artery. Once in the

pulmonary wedge position, measurements of pressure and blood oxygen

saturation are recorded. Following measurement of the wedge pressure, the

catheter is withdrawn into the proximal pulmonary artery, into the right

ventricle and then into the right atrium, with corresponding recordings of

pressure and oxygen saturation.

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Fig. 3 - Right cardiac catheterization

To advance the catheter from the femoral vein to the pulmonary artery,

the tip of the catheter is advanced from the lower right atrium by clockwise

rotation over the tricuspid orifice, and then advanced into the right ventricle.

To reach the pulmonary artery, the catheter must be slightly withdrawn so

that its tip lies horizontally and just to the left of the spine. Clockwise

rotation then causes the tip of the catheter to point upwards towards the right

ventricular outflow tract. The catheter should only be advanced when it is in

this position in order to minimize the risk of arrhythmia and injury to the

right ventricular wall. If these manoeuvres fail to gain access to the

pulmonary artery due to enlarged right-heart chambers, the catheter may be

withdrawn to the right atrium and formed into a large reverse loop by

catching the tip in a hepatic vein and advancing the catheter quickly into the

right atrium. This allows the tip of the catheter to advance through the

tricuspid valve in an upward position. The catheter should then cross the

pulmonary valve and advance to a pulmonary wedge position without

difficulty. If the pulmonary valve cannot be passed, a guidewire can be

employed to facilitate positioning in the pulmonary artery. Once in the

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pulmonary wedge position, measurements of pressure and blood oxygen

saturation are recorded. Following measurement of the wedge pressure, the

catheter is withdrawn into the proximal pulmonary artery, into the right

ventricle and then into the right atrium, with corresponding recordings of

pressure and oxygen saturation.

Access to the right heart through the internal jugular vein is often used

when only right heart catheterization is performed. The key point for a

successful puncture is correct identification of anatomical landmarks. To

puncture the right internal jugular vein, the high anterior approach is

recommended whereby the puncture site is at the top of the triangle formed

by the two heads of the sternocleidomastoid muscle and the clavicle.

Alternatively, ultrasound guidance puncture has been proposed when this

triangle is difficult to localize as is the case in obese or short-necked patients.

Left heart catheterisation

The common femoral artery is punctured as follows: the three middle

fingers of the left hand palpate the pulse and the skin is pierced with the

needle three finger-breadths below the inguinal ligament. The radiological

identification of the femoral head with the puncture performed at the

junction of the upper third and lower two-thirds results in higher puncture

sites than the standard technique but avoids puncture below the femoral

bifurcation and possibly reduces vascular complications. After puncture of

the artery, a 0.89-mm (0.035-inch) J-guidewire should be advanced carefully

into the needle. It should move freely up the aorta and be placed at the level

of the diaphragm. When it is difficult to advance the guidewire close to the

tip of the needle, the wire should be withdrawn to ascertain that forceful

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arterial flow is still present; if not, the needle should be removed and the

groin compressed for 5min. Problems that can be encountered in advancing

the guidewire include severe arterial tortuosity, stenosis, occlusion or

dissection. Left heart catheterization via the femoral approach is performed

using an appropriately sized vascular sheath (we use 45F for diagnostic

coronary angiography, 58F for percutaneous coronary interventions). The

sheath is introduced via the guidewire and flushed with heparinized saline.

For routine diagnostic coronary angiography, intravenous bolus

administration of unfractionated heparin is not required but for long

diagnostic procedures or when a radial approach is used, 30005000 units of

heparin are normally administered.

All left-heart catheters are exchanged via the guidewire, which is

positioned with its tip at the level of the diaphragm. The pigtail catheter for

left ventricular (LV) pressure measurements and angiography can be easily

advanced across the aortic valve in the absence of aortic stenosis. If the latter

is present, a 0.89-mm (0.035-inch) straight guidewire is employed to cross

the valve, with its soft tip leading and pointing towards the stenotic valve

and with the pigtail catheter pulled back into the ascending aorta by about 4

5cm. In this position, the wire tip usually quivers in the systolic jet. The

pigtail catheter remains fixed and the guidewire is moved towards the valve

in attempts to cross it. If this is not possible, the process can be repeated

using a Judkins right coronary catheter or a left Amplatz or Feldman catheter,

which allow better targeting of the valve opening than the pigtail catheter.

When the guidewire has crossed the valve, it should be placed in the left

ventricle, with a loop to minimize the risk of injury to the left ventricle.

Accurate measurement of the true pressure gradient across the stenotic valve

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requires simultaneous pressure measurements in the left ventricle and in the

ascending aorta just above the valves (fig. 4).

Fig. 4 - Left heart catheterization

Another way to approach the left cardiac chambers is via the

transeptal catheterization, which involves right atrium approach followed by

puncture of the intraatrial septul with special needles (fig.5). After puncture

of the intraatrial septum, an introducer sheath is advanced in the left atrium

and than passed through the mitral valve into the left ventricle.

Fig. 5 - Transseptal catheterization - needles for transseptal puncture

Haemodynamic measurements during cardiac catheterization

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Pressure measurements

An important goal of cardiac catheterization is precise assessment of

pressure waves generated by the different cardiac chambers.

Measurement of intracardiac pressure is possible after placing an open

lumen catheter in the respective cardiac chamber, catheter which is

connected to a pressure tranducer which is in turn connected to a monitor.

After calibration of the transducer, the pressure value and waveforms are

displayed on a monitor (fig. 6)

Fig. 6 - Intracardiac pressure measurements

Intracardiac pressure measurements are useful especially for assessment of valvular heart disease severity.

In case of mitral stenosis, cardiac catheterisation is useful for:

1) Assesment of mitral stenosis severity, using the pressure gradient between LA and LV, based on the difference between the pressures in the:

-pulmonary capillary wedge pressure (equal with the one in LA) right catheterisation

-end-diastolic pressure in the LV left catheterisation

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2) Determination of the severity of pulmonary hypertension

Fig. 7 - Assessment of diastolic gradient across the mitral valve in case of mitral stenosis

In case of aortic stenosis, cardiac catheterisation is useful for the

assessment of aortic stenosis severity, based on the pressure gradient

between LV and aorta (fig.8)

1) using retraction of the catheter from the LV in the aorta, or

2) positioning 2 catheters one in the LV and one in the aorta

-peak-to-peak gradient maxim instantaneously

-average gradient tracing the area between the two curves

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Fig. 8 - Assessment of systolic gradient across the aortic valve in case of aortic stenosis

However, positioning of a Pigtail catheter in the LV could be difficult

in aortic stenosis, due to difficulties in crossing a calcified aortic valve.

Therefore alternative techniques for crossing the aortic valve should be used

in these cases (fig. 9)

Fig. 9 - alternative techniques for crossing aortic valve

Cardiac catheterization could also serve for determination of valvular

area using Gorlin formula in case of mitral or aortic stenosis:

AVA = (cardiac output/systolic ejection periodheart rate)/44.3P

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MVA = (cardiac output/diastolic filling periodheart rate)/37.7P

Determination of cardiac output using cardiac catheterization uses

the thermodilution method or the Fick method.

Thermodilution method involves injection of a saline solution in the

proximal end of a special catheter and determination of the modification in

the temperature at the distal part of the catheter, where a termistor is placed.

The result is displayed on a screen (fig. 10).

Fick method requires determination of O2 consumption via

determination of O2 concentration in expired air. According to the Fick

principle, the total uptake or consumption of a substance by an organ is the

product of the blood flow to that organ and the arteriovenous concentration

difference of the substance.

Fig. 10 - determination of cardiac output

Blood oxygen measurement

Oximetry at different levels of cardiac cavities is useful for assesment

of cardiac shunts. Detection and localization of an intracardiac shunt can be

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easily performed using blood oxygen saturation as the indicator, which is

obtained at many different sites within and close to the heart. Quantification

of the shunt is based on measurements of pulmonary (Q p, l/min) and

systemic (Qs) CO.

For shunt determination, blood samples are taken fom different levels

of the cardiac chambers:

-superior RA -medium RA -inferior RA -PA -RV outflow tract -VD - inflow -VCI -VCS -Ao -LV -pulmonary capillar

Catheterization protocol

The following steps are necessary for a complete cardiac

catheterisation procedure:

1. Record phasic and mean pressure in right atrium and aorta

2. Withdraw simultaneously blood samples from right atrium and

aorta for oxygen saturation measurements

3. Advance the SwanGanz catheter sequentially into the right

ventricle and pulmonary artery for pressure measurements and blood

samples for oxygen saturation measurements

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4. Measure cardiac output using the triple lumen thermodilution

catheter (SwanGanz)

5. Advance the SwanGanz catheter to pulmonary wedge pressure and

cross the aortic valve with the pigtail catheter for simultaneous recordings of

left ventricular end-diastolic pressure and pulmonary wedge pressure (same

scale)

6. Deflate the balloon and pull the Swan-Ganz catheter back towards

the pulmonary artery

7. Record simultaneous left ventricle pressure and femoral artery

pressure (through the arterial sheath) or aortic pressure (via double lumen

catheter)

8. After left ventriculography (if needed) pull back from the left

ventricle into the aorta.

Normal pressure ranges (mmHg), oxygen saturations (%), and oxygen

volume percentages in resting conditions are indicated below:

S D Mean O2 sat O2 volume % RA 5 75 15 RV 24 4 75 15 PA 24 10 15 75 15 PCW 12 LV 120 12 95 19 LA 12 95 19 Ao 120 80 95 19

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Ao: aorta; LV, left ventricle; LA: left atrium; PA, pulmonary artery; PCW, pulmonary wedge pressure; RA, right atrium; RV, right ventricle.

Determination of vascular resistance is useful for estimation of

reversibility degree of pulmonary hypertension, based on determination of

pulmonary vascular resistance before and after oxigen or nitric oxide

inhalation, effort or administration of sodium nitropruside

Ventriculography is a technique based on injection of contrast

material into the LV, serving for assesment of LV motion and mitral

regurgitation degree (fig. 11).

Fig. 11 - Left ventriculography

Ventriculograms are usually recorded at 3060 frames/s, and

radiographic contrast agent is injected in adults at rates of 1015mL/s for a

total volume of 3050mL.

Based on information provided by ventriculography, mitral

regurgitation severity is estimated on the following scale:

Trivial (grade 1 or 1+/4+): contrast material enters the left atrium during

systole without filling the entire atrial cavity and is cleared in the subsequent

beat

Mild (grade 2 or 2+/4+): contrast opacification of the left atrium is less

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dense than the opacification of the left ventricle but contrast is not cleared

with each beat

Moderate/severe (grade 3 or 3+/4+): opacification of the left atrium is as

dense as the opacification of the left venticle

Severe (grade 4 or 4+/4+): opacification of the left atrium greater than that

of the left ventricle and/or complete atrial filling in one systole and/or

contrast opacifies the pulmonary veins

Ventricular volumes are possible to be determined using

ventriculography. For the calculation of LV volume, the outermost margin

of visible radiographic contrast is traced. Volume (V) is computed using

long-axis (L) and short-axis (S) measurements (V = [frac16] LS 2) or area

length measurements (V = 8A 2/3L) using an ellipsoid approximation for

ventricular shape.

Ventriculography also serves for assessment of wall motion of

different ventricular segments according to their projection (fig. 12).

Aortography is represented by injection of contrast material in aorta

(fig. 12) and serves for assesment of severity degree of aortic regurgitation,

on the following scale:

Trivial (grade 1 or 1+/4+): contrast visible in the left ventricle, without

Fig. 12 - Regional wall motion during left ventriculography as assessed in the right and left oblique views

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reaching the apex, clears during each heart beat

Mild (grade 2 or 2+/4+): contrast opacification less dense than that of the

ascending which does not clear during a single heart beat

Moderate/severe (grade 3 or 3+/4+): opacification of the left ventricle as

intense as that of the ascending aorta

Severe (grade 4 or 4+/4+): opacification of the left ventricle more intense

than that of the ascending aorta and/or full left ventricular cavity opacified in

one beat

Fig. 12 - Aortography

5. Coronary angiography

Coronary angiography, represented by injection of contrast material

into the ostium of the coronary arteries, has become nowadays the golden

standard for for identification of coronary artery stenoses or occlusions

caused by ischaemic heart diseases.

Indications of coronary angiography

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Main indications of coronary angiography are represented by:

-Unstable angina or acute myocardial infarction for urgent revascularisation

-Stable angina class III and IV after medical treatment

-Survivals of cardiac arrtes

-Postrevascularization ischaemia (suspicion of stent thrombosis)

-Before open heart surgery for valvular heart diseases, in those >50 years.

-High risk for coronary artery disease in non-invasive testing

-For safety reasons (pilots, drivers)

-After AMI especially if EF is

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-Stroke in evolution

-Acute renal failure

-Active endocarditis

Approach

The most used approaches for coronary angiography are the femoral

approach and radial approach (fig. 13). Both use the Seldinger technique for

puncture of the femoral/radial artery (fig. 14)

Fig. 13 a) Femoral approach b) Radial approach

Fig. 15 - Seldinger technique

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The main complications of femoral access are: retroperitoneal

bleeding (more frequent if body surface > 1.72 m2, in case of suprainguinal

acces, in case of puncture of posterior arterial wall or excessive tortuosity),

pseudoaneurism, arterio-venous fistula and hematoma. To overcome the risk

of bleeding associated with femoral puncture, different types of closure

devices have been introduced in the market (Vasoseal, AngioSeal, Duett,

QuickSeal, etc - fig.16). Closure devices present multiple advantages against

the manual compression: help to reduce bleeding at the site of the puncture,

lower mortality, and are preffered by the patients

Fig. 16 - closure devices

Technique

Catheter selection

Pre-shaped catheters (e.g. Judkins, Amplatz) can be used for injection

of both coronary vessels, not only via the femoral and left radial or brachial

approach but also the right radial/brachial approach. A large spectrum of

different catheter configuration is available nowadays (fig. 17), adapted for

each particular case (large or small aortic root, different angulation of

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coronary origin, etc), the most used being the Judkins and Amplatz types

(fig. 18).

Improvements in catheter technology have allowed the flow rate

obtained with old 8F (1F = 0.33mm) diagnostic catheters to be achieved

with 6F thin-walled catheters and satisfactory coronary opacification with 4F

and 5F diagnostic catheters. Newly developed automatic injectors with

adjustable increases in injection pressure have the potential to allow more

consistent homogeneous opacification of large left coronary arteries through

45F catheters.

When retrograde bleeding ensures the catheter has been purged of air,

a pressure line is connected and a test injection performed, often showing

that the catheter is already engaged or is located immediately below or in

front of the ostium. In the latter case, gentle withdrawal of the catheter tip

(helped by asking the patient to take a deep breath) will allow engagement of

the catheter tip in most cases. If the tip of the catheter immediately closes in

the ascending aorta, prolonged attempts with the same catheter should be

avoided and rapid switching to a larger catheter is probably advantageous in

terms of time lost and contrast used. When it is known that the coronary

Fig. 17 - Different types of catheters for coronary angiography

Fig. 18 - a) Judkins L and R curve . b) Amplatz L and R curve

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ostia are in an unusual position (aortic valve disease, Marfan syndrome,

congenital heart disease), it is probably worthwhile performing an aortic

angiogram in the left anterior oblique view in order to guide catheter

selection, since this may require unusual shapes.

Cannulation of left coronary artery

Selection of coronary catheters should aim at an optimal coaxial

atraumatic intubation of the coronary artery and should be based on the size

of the aortic root. In the majority of cases standard 4.0 Judkins catheters can

be used. If it is known from previous invasive or non-invasive examination

that there is an enlarged ascending aorta, a 4.5 or 5.0 left Judkins catheter

should be preferred. Smaller sizes, 3.5 or 3.0 Judkins, can be a first choice in

small females or for right radial approaches.

The optimal view for engaging both the right and left coronary

arteries is the left anterior oblique view where the ostium is not covered by

the aorta. The left coronary artery requires only minimal catheter

manipulation; the J-tipped 0.89-mm (0.035-inch) wire is atraumatically

advanced to the level of the aortic valve and the tip of the previously flushed

Judkins catheter is opened as low as possible pointing to the left coronary

ostium (fig. 20).

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Cannulation of Right coronary artery

Catheter selection for cannulation of the right coronary artery (RCA)

should be based on the same policy as for the left coronary artery, taking

into account the size of the aortic root. In the left anterior oblique or lateral

view, the catheter must be rotated to point to the left of the screen and this is

better achieved when the rotation is performed during a slow pull-back

motion of the catheter from the right coronary sinus. Breath-holding after a

deep inspiration may facilitate this manoeuvre. In 1015% of cases a high

origin of the RCA complicates the search for the right coronary ostium.

Even in the presence of a hypoplastic non-dominant RCA, selective injection

is still required because small proximal branches can be an important source

of collaterals for occluded vessels. It is often possible to obtain a semi-

selective injection with the Judkins catheter that will further guide catheter

selection. A multipurpose catheter should be used for downward-looking

RCAs, and Amplatz right 2 or Amplatz left 1 or 2 are required in patients

with high take-off and/or with dilatation of the coronary sinus and ascending

aorta. Careful review of the images should be performed before finishing the

examination in order to avoid missing a separate origin from the aorta or an

abnormal origin from the proximal RCA of the LCX, the most frequent

Fig. 19 - catheter manipulation for cannmulation of left coronary artery

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coronary anomaly, or the separate origin of a conus branch that provides

important collaterals to occluded arteries.

Contrast injection should be sufficiently rapid and large to fully

replace the epicardial vascular volume and avoid the phenomenon of

streaming or incomplete visualization. On the other hand, angiographic

acquisition should be prolonged to allow visualization of the distal vessels,

identification of thrombolysis in myocardial infarction (TIMI) flow, and

characterization of type of dissection (with/without persistence of contrast at

the end of the injection). An important determinant of injection duration is

the need to visualize collaterals for occluded vessels, which also means

adjustment of the view to include the recipient vessel in the image.

Visualisation of coronary circulation

There are 3 types of coronary circulation, according to the distribution

of coronary arteries:

1. Right dominance - 80% of cases, when the diafragmatic wall is

irrigated by the right coronary artery

Fig. 20 - catheter manipulation for cannmulation of right coronary artery

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2. Left dominance - 10-15% of cases, when the diafragmatic wall is

irrigated by the left coronary artery

3. Codominant- 10% of cases, when the diafragmatic wall is irrigated

by both coronary arteries

Left coronary artery

Left coronary artery (Left main) divides immediately after originating

from aorta into 2 major vessels: the Left Anterior Descendent (LAD)

coronary artery and the Circumflex artery (Cx).

The branches of left coronary artery are presented in fig. 21

1 Left main, 2 Proximal LAD (SI), 3 - Medial LAD (SII), 4 - Distal LAD (SIII), 5 - Proximal Cx, 6 - Distal Cx, 7 - Marginal artery, 8 - 1st diagonal, 0 - 2nd diagonal, 10 - septal arteries, 11 - 2nd marginal.

Fig. 22 - examples of left coronary angiography

To delineate the branching of the left main coronary artery from the

aorta and its bifurcation into the left anterior descending (LAD) and left

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circumflex (LCX) arteries (or trifurcation if an intermediate branch is

present), the most used incidence is the so-called spider view (left 4055,

caudal 2540).

In the left cranial view (3045 left, 2540 cranial) the LAD is

further elongated by asking the patient to take a deep breath and maintain

breath-holding during injection. The cranial view also offers optimal views

of the mid and distal segments of the LCX, and is especially useful in the

presence of a dominant LCX. The lateral view provides excellent

visualization of the mid/distal LAD around the apex, information which is at

most complementary to right caudal views.

Right coronary artery

Right coronary artery has few branches in the first, second, and third

segments (from the ostium to the crux cordis) and often two views (left

anterior and right anterior oblique views) are sufficient to identify all

stenoses, including eccentric stenoses. The lateral view might be ideal for

assessment of the mid segment of the artery and may occasionally be used as

a working projection for occlusions in this segment or stent positioning.

The branches of left coronary artery are presented in fig. 23

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Fig. 23 - 1 - first (orizontal) segment, 2 - 2nd (vertical) segment, 3 - 3rd (orizontal) segment, 4 - posterior interventricular branch, 5 - retroventricular artery, 6 - conus artery, 7 - sinus node artery, 8 - right ventricular artery, 9 - right marginal artery, 10 - artery of the AV node, 11- inferior septal branches

Fig. 24 - examples of right coronary angiography

Complications of coronary angiography

The most frequent complications of angiography occur at the catheter

entry site. Closure devices have reduced the time to ambulation, increased

patient comfort, and shortened the hospital stay, but do not appear to have

modified the bleeding risk and have added some rare specific new

complications (infection, embolization, or arterial stenoses due to

components of the closure device or procoagulant factors injected into the

bloodstream).

Large haematomas requiring drainage, blood transfusions, prolonged

bed rest, and hospitalization are rare and often the consequence of the

inability to comply with bed rest, or the clinical need for prolonged

anticoagulation.

Other more serious vascular complications include pseudoaneurysm,

fortunately often closed with ultrasound-guided compression and/or

34

selective thrombin injection, arteriovenous fistulae, arterial thrombosis, and

distal embolization.

The most dreadful but fortunately rare vascular complication is

retroperitoneal bleeding, mostly managed conservatively, while iliac or

aortic dissections tend to seal spontaneously if antegrade flow is preserved.

The frequency of serious complications, such as death, myocardial

infarction, or cerebrovascular accident with permanent damage, is very low

(0.10.2%).

Myocardial infarction is often due to catheter-induced ostial damage

due to pre-existing severe pathology or the presence of unstable plaques at

risk of embolization and can potentially be treated with angioplasty and

stenting.

Stroke is the consequence of thromboembolism due to thrombi in the

access sheath or the catheter, dislodgement of plaques from the iliac vessels

or aorta, calcium from the aortic valve, or thrombi in the left ventricle.

Meticulous attention to catheter flushing and atraumatic wire-lead insertion

can reduce but not eliminate the risk, whilst there is no evidence that

systemic heparinization is required for diagnostic catheterization.

Reactions to the contrast medium (nausea, vomiting, rash) are very

rare and the amount of contrast used for a diagnostic angiogram cannot

induce permanent renal damage unless a severe previous dysfunction was

present.

Bradycardia and hypotension develop because of periprocedural

vasovagal reactions, prevented by generous sedation, liberal local

35

anaesthesia, reassurance, and appropriate filling with intravenous fluids.

Other major arrhythmias (ventricular fibrillation and tachycardias,

supraventricular arrhythmias) can be induced by catheter damping,

excessively prolonged injection, or mechanical stimulation.

6. Percutaneous coronary interventions

Percutaneous Transluminal Coronary Angioplasty (PTCA), known

also as Percutaneous Coronary Intervention (PCI), represents dilatation of a

coronary stenosis using a dedicated catheter with a deflated balloon at its tip,

36

which is advanced at the site of the coronary plaque under X-ray control (fig.

25). At this site, the balloon is inflated using an external syringe and

compresses the coronary plaque against the vessel wall.

Fig. 25 - PTCA technique.

Coronary stenting represents introduction, using femoral or radial

access, of a coronary stent which is expanded against the vessel wall at the

site of the coronary plaque using an external syringe and remains in place at

the site of the coronary stenosis, isolating the atheromatous plaque and thus

preventing the restenosis(fig. 26).

A B C

37

Fig. 26 A -coronay artery stenting. B- angiographic aspect before stenting. C - angiographic aspect after stenting

Traditionally, 3 types of coronary stenoses have been described:

Type A - > 85% succes rates, low risk

-length

38

-excessive tortuosity of the proximal segment

-extremely angulated segment, >90 degrees

-total occlusion, >3 months

-major collateral branch involved

-degenerated saphenous graft with friable content.

Materials for PTCA

1. Guiding catheters

The guiding catheters are manipulated in order to be positioned in the

ostium of the coronary artery (fig. 27). They have a standard diameter of 350

m, and a length between 150 and 350 cm.

Fig. 27 - positioning of the guiding catheter in the ostium of the coronary artery

Similar with coronary diagnostic catheters, there are many different

types of shapes of guiding catheters (Judkins, Amplatz, etc) - fig. 28.

39

Fig. 28 - canulation of left and right coronary ostium with different types of catheters.

2. Guidewires

A guidewire is a device used to cross the coronary lesion. After

crossing the coronary lesion, a PTCA balloon catheter is advanced along the

guidewire until it reaches the coronary lesion. Usually, the guidewires have a

diameter of 0.010 - 0.018, a tip diameter of 0.014 0.009, a standard

length of 175-190 cm, and 3 components: a core, a tip and a coating (fig. 29).

3. PTCA balloons

40

PTCA balloons are catheters having attached at their distal tip a

deflated balloon (fig. 30), which can easily be inflated in order to compress

the plaque.

4. Coronary stents

Coronary stents are metallic devices which are surmounted on a

deflated PTCA balloon and are placed at the site of coronary plaque in order

to treat it and prevent restenosis (fig.31).

Fig. 31 - coronary stent at the site of the plaque

The major two types of stents are available nowadays:

-Bare metal stents are classical stents, that are not covered with antiproliferative substances, and

-Drug-eluting stents are stents covered with anti-restenotic medication.

41

Bioabsorbable stents have also been introduced in the recent years,

with similar results as for DES.

Advances in techniques, equipment, stents and adjuvant therapy have

established PCI as a routine and safe procedure in patients with SCAD and

suitable coronary anatomy. The mortality risk associated with the procedure

in SCAD is 0.5%.

Bare metal stents (BMS) are associated with a 2030% rate of

recurrence of angiographic stenosis within 69 months after implantation.

Drug-eluting stents (DES) reduce the incidence of angiographic restenosis

and ischaemia-driven repeat revascularization. For the first generation of

DES, this benefit has been extensively demonstrated in spite of a slightly

higher incidence of late and very late stent thrombosis, related to delayed

endothelialization, which requires longer dual antiplatelet therapy (DAPT) to

prevent stent thrombosis. First- generation sirolimus-eluting stents (SES)

and paclitaxel-eluting stents (PES) have been extensively compared in head-

to-head randomized controlled trials. Angiographic results were better with

SES and translated into significant differences in terms of repeat

revascularization.

The most recent or second- generation DES (with thinner struts and

biodegradable or more biocompatible polymers) showed superior clinical

outcomes for both efficacy and safety when compared with first-generation

DES.

New-generation DES have been associated with lower rates of stent

thrombosis, and recent data from registries and randomized controlled trials

suggested that a shorter duration of dual antiplatelet therapy might be

sufficient in stable coronary patients.

42

Special devices are used in coronary interventions, in special complex

cases. Among them are:

- Thrombectomy devices, used in cases of large thrombotic material, for

removal of the thrombus especially in cases of acute coronary syndromes

- Aterectomy devices, rotational or directional, which fragments the coronary

plaque and eliminate the debris

- Laser catheters, used especially for dissipation of coronary plaque and

thrombus

43

- Maneuvrable guidewires, used especially in cases with difficult abord

Microdissection, useful expecially for penetratic the fibrous cap of a chronic

total occlusion.

Safe cross, especially in complex cases when it generates an audio signal

each time the catheter is closer than 1 mm to the vessel wall, eliminating the

risk of perforation.

44

Antiembolic filters which could be proximal or distal to the lesion

Proximal antiembolic protection devices Distal antiembolic protection devices

Primary PCI in STEMI

There is general agreement that reperfusion therapy should be

considered if there is clinical and/or Electrocardiographic evidence of

ongoing ischaemia, even if, according to the patient, symptoms started 12 h

before as the exact onset of symptoms is often unclear, or when the pain and

ECG changes have been stuttering.

There is, however, no consensus as to whether PCI is also beneficial

in patients presenting 12 h from symptom onset in the absence of clinical

and/or electrocardiographic evidence of ongoing ischaemia. In such

asymptomatic late-comers, a small (n 347) randomized study has shown

myocardial salvage and improved 4-year survival resulting from primary

PCI, compared with conservative treatment alone, in patients without

persistent symptoms 12 48 h after symptom onset. Primary PCIdefined

as an emergent percutaneous catheter intervention in the setting of STEMI,

without previous fibrinolytic treatmentis the preferred reperfusion

strategy in patients with STEMI, provided it can be performed expeditiously

(i.e. within guideline-mandated times), by an experienced team, and

45

regardless of whether the patient presents to a PCI-capable hospital. If FMC

is via an EMS or at a non-PCI-capable centre, transfer via the EMS to the

catheterization laboratory for PCI should be implemented Immediately. An

experienced team includes not only interventional cardiologists, but also

skilled support staff. This means that only hospitals with an established

interventional cardiology programme (available 24/7) should use primary

PCI as a routine treatment. Lower mortality rates among patients undergoing

primary PCI are observed in centres with a high volume of PCI procedures.

Primary PCI is effective in securing and maintaining coronary artery patency

and avoids some of the bleeding risks of fibrinolysis. Randomized clinical

trials comparing timely primary PCI with in-hospital fibrinolytic therapy in

high-volume, experienced centres have repeatedly shown that primary PCI is

superior to hospital fibrinolysis.

According to all these data, the European Society of Cardiology

elaborated the guidelines for STEMI treatment presented below:

European guidelines on STEMI treatment

46

According to the recommendation of the European Society of

Cardiology, the prehospital management of STEMI patients must be based

on regional networks designed to deliver reperfusion therapy, with efforts

made to make primary PCI available to as many patients as possible.

47

7. Imaging in interventional cardiology

Intracoronary ultrasound imaging

Intravascular ultrasound represents intracoronary visualization of

atherosclerotic plaques using a dedicated catheter which is advanced into the

coronary lumen, having a miniaturized flexible intracoronary ultrasound

probe mounted on the tip, which generates high-resolution cross-sectional

images by spinning a single piezoelectric crystal at 360 degrees or by

activating in sequence multiple (64) transducer elements. The technique is

useful for measurements of vessel dimensions (diameter, area). When

associated with Virtual Histology, it allows quantification of coronary

plaque components. Virtual Histology is an IVUS-derived technique which

provides a colour codification of the atheromatous plaque based on echo

density of the plaque component. According to ultrasound density, the

plaque components are classified as fibrous, calcific, soft atheroma and

necrotic core. This technique allows not only visualization of these

components but also their quantification and is currently used as a golden

standard for characterizing vulnerable plaques, which are prone to plaque

rupture and consecutive development of an acute coronary syndrome.

Unstable plaque are characterized by VH-IVUS specific markers, such as a

large necrotic core especially when situated in the proximity of the intimal

layer, a large content in soft atheroma and positive remodeling. All these

features are currently used in the cardiac catheterization laboratories to asses

the risk associated with coronary stenoses.

48

Calcification, detected with greater sensitivity than with angiography,

can be located within the plaque, from superficial subendothelial calcium

speckles to deep deposits at the base of the plaque, and can be quantified

based on their circumferential extension, measured in degrees or quadrants,

and length.

Fig. 32 - Intravascular ultrasound with virtual histology

Multislice 64 computed tomography coronary angiography is a

new technology which allows noninvasively quantification of atherosclerotic

burden of coronary lesions and can therefore predict risk of cardiac events. It

can not only evaluate the presence of obstructive coronary artery disease, but

also can provide a plaque characterization classified as calcified,

noncalcified or mixed.

49

Optical coherence tomography

OCT is a novel imaging modality that is capable of visualizing vessel

anatomy at a resolution around ten times greater than IVUS due to the much

shorter wavelength of the imaging light.

Current OCT images are obtained via 0.019 in imaging wires

containing optical fibres, at a peak wavelength in the 12801350nm band,

that enables a 1015 tissue axial resolution. Images are then displayed

using a log false colour scale, at 20 frames/s and 200 lines/frame. These

parameters have been further improved with the use of frequency domain

OCT which allows acquisition of 100 frames/s and 500 lines/frame, allowing

a more rapid pull-back and a wider field of view with maintained or

improved image quality. The superb resolution of OCT is obtained at the

expense of a limited tissue penetration, which is the main limitation of OCT.

Penetration is dependent on tissue characteristics and is between 0.51.5mm

of imaging depth; it is minimal in presence of thrombus, poor for superficial

necrotic lipid pools, higher for calcific components, and maximal for fibrous

tissues.

Calcifications within plaques are identified by the presence of well-

delineated, low back-scattering heterogeneous regions. Fibrous plaques

consist of homogeneous high back-scattering areas. Necrotic lipid pools are

less well-delineated than calcifications and exhibit lower signal density and

more heterogeneous back-scattering than fibrous plaques. There is a strong

contrast between lipid-rich cores and fibrous regions within OCT images.

Therefore, lipid pools most often appear as diffusely-bordered, signal-poor

regions (lipid pools) with overlying signal-rich bands, corresponding to

50

fibrous caps Pathological studies of plaques leading to fatal events have

established 65m as the threshold of fibrous cap thickness that best

identifies vulnerable lesions so that this value is often adopted as the cut-off

threshold for identifying thin capped atheromas prone to rupture in vivo.

Thrombi are identified as masses protruding into the vessel lumen

discontinuous from the surface of the vessel wall. Red thrombi are

characterized by high-backscattering protrusions with signal-free shadowing.

White thrombi appear as signal-rich, low-backscattering billowing

projections protruding into the lumen.

Fig. 34 - Left panel: normal three layer appearance in a 31-year-old female patient can be appreciated, with the muscular media being shown as a low signal layer comprised between internal and external lamina. Right panel: eccentric coronary plaque with fibrous (arrow) and calcific (arrow-head) components.

OCT has the potential to identify inflammatory cells such as clusters

of macrophages, seen as bands of high reflectivity in OCT images. When

macrophages are located in a plaque with a lipid pool, macrophage streaks

appear within the fibrous cap covering the lipid pool. Acute plaque

ulceration or rupture can be detected by OCT as a ruptured fibrous cap that

connects the lumen with the lipid pool. These ulcerated or ruptured plaques

may occur with a superimposed thrombus and this can impair the

visualization of the underlying rupture.

51

Optical coherence tomography for assessment of coronary interventions

Poor penetration limits the practical value of OCT for preintervention

imaging, making this technique less suitable than IVUS for sizing balloons

and stents. Still lumen area, with the exception of the largest vessels, can be

easily detected with OCT. Potentially, all the considerations made before to

determine when treatment is warranted and when the lumen inside the stent

matches the proximal and distal

A great value of OCT is the superior ability to study apposition and

intimal coverage after stent implantation. Struts are seen as dense strips

because metal, unlike calcium, cannot be penetrated by OCT. Although the

intima immediately below the strut cannot be seen, the artefacts around

struts are much less prominent than with ultrasound and the relationship

between strut and surrounding intima can be studied. Struts often appear as

protruding from the intima but the physical thickness of the strut must be

considered to judge apposition. Thinner stent struts have been shown to have

fewer protruding or unapposed struts than thicker stent struts but no

longitudinal observations correlating these findings with late coverage or

clinical events are available at this stage.

52

Imaging the vulnerable plaque

Intracoronary vulnerable plaques are associated with a high risk for

plaque rupture and development of an acute coronary syndrome. Therefore

detection of vulnerable plaques and quantification of plaque vulnerability

and its risk for further rupture and complications represents one of the main

goals of the new imaging techniques in cardiology.

Detection of vulnerable plaues is one of the most challenging issues

raised by the recent developments in imaging techniques in cardiology.

Ability to detect features which characterise the unstable plaque continues to

be in the focus of several new imaging techniques. Detection of vulnerable

plaque is of extreme importance due to the well-known risk associated with

these plaques. Rupture of an unstable plaque rapidly evolves towards

development of an acute coronary syndrome, either ST or nonST elevation

myocardial infarction or unstable angina.

Intravascular ultrasound represents nowadays a golden standard for

detection and assessment of vulnerable plaques, due to its ability, when

associated with virtual histology, to distinguish between soft atheroma with

a lipid reach core and eventually a necrotic core, characteristic for unstable

plaques, and fibrous atheroma or calcified plaques typically associated with

stable plaques. Another important information provided by IVUS for

assessment of unstable plaques is the evaluation of the fibrous cap of the

coronary plaque, being known nowadays that a thin fibrous cap is

significantly associated with a high risk for development of an acute

coronary syndrome as a marker of plaque instability. Assessment of vascular

remodeling, which has been shown to be correlated with a significant risk

for development of an acute coronary syndrome, is another important

53

application of IVUS with significant potential impact in detecting the risk

associated with a vulnerable plaque. Another method useful for evaluation of

coronary plaques is represented by Multislice Computed Tomography

Coronarography (MSCT), which presents the advantage of obtaining

complex information related to coronary plaques via a noninvasive method.

The gold standard for assessing vulnerable plaque is nowadays

represented by Intravascular Ultrasound associated with Virtual Histology

(IVUS-VH) because of excellent visualization of intracoronary plaques

associated with exact quantification of low-density atheroma within the

plaque. Indeed, virtual histology techniques is a recently developed

application of intravascular ultrasound technology, in which coronary

plaques are color coded according to their content in low density, vulnerable

atheroma, fibrous atheroma, calcifications or necrotic core. After tracing the

external and internal borders of the coronary plaque, the plaque is displayed

in different colors according to its content in lipid-reach atheroma or stable

atheroma, and in the same time a graphical display of the percentage of

plaque burden with low or high density atheroma is displayed on the screen.

Considering the concomitant possibility of measuring the thickness of

the fibrous cap with IVUS and to evaluate the vascular remodeling in the

immediate proximity and distality of the plaque, it is clear that the IVUS

examination associated with virtual histology provides all the necessary

information to estimate the vulnerability of the plaque, as it provides

important information regarding several parameters known as being

associated with plaque instability and evolution towards development of an

acute coronary syndrome (presence of necrotic core, lipid-reach burden, thin

fibrous cap, vascular remodeling).

54

One disadvantage of IVUS technique is represented by difficulty in

visualization of intracoronary thrombus, which is a major finding associated

with an acute coronary syndrome especially in acute cases such information

could be essential to establish the proper treatment strategy. In these cases an

alternative interventional imaging method could be represented by optical

coherence tomography (OCT), which offers superb visualization of

intracoronary thrombus and coronary plaque in the same time, but without

the possibility of virtual histology analysis.

However, the discomfort associated with an interventional technique

and the high cost of the IVUS or OCT technologies and catheters precludes

IVUS or OCT technology from being used on a large scale for detection of

vulnerable plaques.

Noninvasive techniques have emerged to replace interventional

imaging techniques in complex assessment of intracoronary plaques. The

recent progress in non-invasive imaging techniques represented by

Multislice 64 Computed Tomography Coronaroangiography (MSCT) has

made possible noninvasive visualization of coronary plaques along a

complex assessment of coronary lesions. MSCT analysis of intracoronary

plaque is mainly used on a large scale in present in order to classify the

coronary plaques as obstructive or non-obstructive according to the degree

of luminal narrowing realized by the stenosis. Another important application

of MSCT is represented by calcium scoring which is used in many times as a

screening tool to assess the cardiovascular risk, based on calculation of

calcium burden within the coronary arteries, which has been shown to be

directly correlated with the evolution of the patients towards development of

a cardiovascular event. However, in cases with very high calcium score

invasive coronarography is indicated as the severe calcification of the

55

coronary arteries makes it very difficult to provide an accurate assessment of

the coronary arteries due to intense reverberations.

One of the most important applications of MSCT technique is

represented by possibility to determine intraplaque densities and therefore to

estimate the content in low-density atheroma versus high-density atheroma,

providing a differentiation between low-density fibroadipous atheroma and

high-density calcified atheroma. Similar with virtual histology analysis, a

color coded representation of the coronary plaque is displayed, in which the

atheroma is represented in different colors according to its content in low-

density or high-density atheroma. One of the main issues raised by this

approach is the difficulty to differentiate between low-density fibrous

atheroma which is a stable atheroma, and low-density adipous, cholesterol

reach atheroma, which is a very unstable one. Therefore definition of a

cutting point of plaque density, according to which we would be able to

differentiate the unstable atheroma with a density below the cutting point,

from the stable atheroma with a density above the cutting point, would be of

extreme importance for a proper assessment of plaque-related risk. Such a

cutting point has not been identified yet in the literature, however there are

several ongoing studies to asses the role of MSCT in assessing markers

related to plaque vulnerability.

The detection of vulnerable plaques is one of the most challenging

tasks made possible by the recent developments in cardiovascular imaging

technologies. Taking into consideration the significant risk associated with

vulnerable plaques, which are prone to rupture and rapid evolution towards

the development of Acute Coronary Syndromes, the ability to detect features

that characterize unstable plaques is of extreme importance. If rupture-prone

56

plaques could be identified in time, the appropriate initiation of adequate

therapeutic measures could prevent the evolution to an acute coronary event.

A vulnerable plaque is characterized by a large necrotic core, a thin

fibrous cap demonstrating macrophage infiltration, a large lipid pool, and

several specific features such as positive remodeling (PR) or spotty

calcifications (SC). When these characteristics are present, the fibrous cap

can rupture and the lipid core, which is thrombogenic, is then exposed to the

blood flow, inducing thrombus formation and the development of ACS.

The morphological characteristics associated with unstable plaques

are generally evaluated using three main imaging methods: Intravascular

ultrasound with virtual histology (VH-IVUS), Coronary Computed

Tomography Angiography (CCTA), and Optical Coherence Tomography

(OCT).

Intravascular ultrasound is currently the gold standard for the

detection and assessment of vulnerable plaques due to its ability, when

associated with virtual histology, to differentiate the soft atheroma with a

lipid reach or necrotic core, which is typically associated with vulnerable

plaques, from a fibrous or calcified atheroma, which is generally associated

with stable plaques. VH-IVUS is able to combine intracoronary imaging

data with a color-coded representation of plaque components, which are

classified as fibrotic, fibro-fatty, calcified or necrotic core, while at the same

time offering the possibility for precise quantification of these components.

Cardiac Computed Tomography Angiograph is another imaging

technique that can identify specific parameters associated with plaque

vulnerability, such as PR, SC and burden with low attenuation plaque (LAP).

It has been shown that a PR on CCTA is associated with higher percentages

of necrotic cores within the plaque on IVUS and that the percentage of the

57

necrotic core by IVUS is significantly higher in plaques with SC identifiable

by CCTA compared to non-calcific plaques. However, although these

studies have demonstrated the association between the presence of different

CT and IVUS features of coronary plaques in different clinical settings, the

precise correspondence between plaque components classified on the basis

of CT attenuations and VH-IVUS derived components, has not been clearly

established yet.

Available softwares have enabled CCTA to be used for quantitative

analysis of plaque components based on different CT attenuations within the

plaque. In most ACS cases, CCTA plaque quantification demonstrates a

mixed composition of the coronary plaques, containing variable proportions

of a lipid-reach core with a low CT density (with mean attenuation values

reported in a range between 11 and 99 HU), a fibrous component with

higher CT densities (with mean attenuation values reported in a range

between 77 and 121 HU), and calcium.

Several studies that compared CCTA with intravascular ultrasound

have validated the role of CCTA for the detection of coronary plaques,

reporting sensitivities and specificities that vary between 80 and 90%.

However, CT imaging is not restricted only to plaque visualization, as it

provides additional information regarding plaque burden, composition and

remodeling, which are directly correlated with plaque vulnerability.

In a prospective study including 1059 patients who were followed for

a mean period of 2.3 years after having undergone CCTA, Motoyama et al

demonstrated that specific plaque parameters such as PR and low CT

attenuation may be associated with a particularly high risk for plaque rupture

and the development of an acute coronary event. Another retrospective study

demonstrated that culprit lesions present a more positive remodeling (815 vs.

58

12%), more low-density (

59

Fig. 38 - Vulnerable plaque by Cardio CT - dark spots representing necrotic core of the

plaque

Intracardiac echography

Intracardiac echography represents visualization of heart structures

using special miniaturizd transducers placed at the tip of intracardiac

steerable catheters, which are advancd using standard interventionl

techniques in the heart chambers.

Information provided by intracardiac echocardiography are in a

certain extent superposable with those offered by transesophageal

echocardiography, still carrying the advantage of a significantly higher

comfort for the patient, therefore intracardiac ech is the procedure of choice

in many structural interventions, interventions that take usually a longer time

and require echocardiographic monitorization due to their complexity.

Fig. 39 - Intracardiac echocardiography - technique and catheter

60

8. Structural interventions

1) Interventional closure of Atrial Septal Deffects and Patent

Foamen Ovale

Atrial Septal Deffects are the most common congenital heart diseases

that could be encountered de novo in an adult. In patients with significant

ASD, ASD closure leads to a symptomatic improvement and regression of

right ventricular size and pulmonary hypertension. The best outcomes of this

procedure are encountered in young patients. The main indications for ASD

closure are the clinical symptoms in presence of a significant shunt and

dilated RV, while main contraindications are represented by Eisenmenger

physiology, pulmonary hypertension and sinous venosus or ostium primum

type. Also, all ASDs regardless of size in patients with suspicion of

paradoxical embolism should be considered for intervention.

The success rates for ASD closure are quite high, approaching 98%,

the most important key for success being the correct assessment of ASD

type before the procedure. In order to be amenable for closure, a defect

should have a rim of at least 5 mm to assure the correct apposition and

stabilisationof the disks. The procedure of interventional closure of ASD

involves placement of an occluder at the site of the defect, wihch is

advanced using right heart catheterization, passes through the defect and is

than opened to close the deffect and released (fig. 40-42).

61

a b c d e

Fig. 40: Interventional closure of ASD. The Device catheter placed into the LA (a), than the device fed into the catheter until the proximal part emerges into the LA (b), and the device catheter retracted against the septum until resistance is felt (c). Catheter is withdrawn until the proximal part emerges from the catheter (d), followed by release of the proximal disk and the device is disengaged from the insertion catheter (e)

Fig. 41 - schematic representation of ASD closure.

Fig. 2 - Implantation of Amplatzer occluder device and intracardac echo control.

62

Different types of occluders have been manufactured by different

companies, with similar succe rates in providing a complete closure of the

defect (fig. 43). The most commonly used occluders for ASD are Amplazer,

Premiere, Cadioseal, Starflex, Helex and Intrasept.

Amplatzer Cardioseal Starflex Helex Premiere Intrasept

Fig. 43 - different types of closure devices

While ASD is a communication between two atria, usually

complicated by pulmonary hypertension, the PFO represents a lack of fusion

of the flap-like opening between the atrial septum primum and secundum.

The closing procedure is similar in case of Patent Foramen Ovale, in

which the indication is mainly based on the suspicion of the associated

paradoxical thromboemblism,multiple neurologic events and eventually

migrena.

However, different types of septal morphology exists in these cass (fig.

44), some of them being quite challenging and involving a higher degree of

difficulty for the operator. Assessment of anatomical variations that may

affect the procedure and device choice is based on the presence of atrial

septal aneurysm, the degree of separation from septum secundum, the length

of septal overlap and the evaluation of the septum secundum

63

Fig. 44 - Different types of difficult septum morphology

2) Interventional closure of Ventricular Septal Deffects

Ventricular Septal Deffects is associated in almost 30% of all

congenital heart diseases and the interventional treatment of VSD is much

more complicated that of ASD, due to the presence of valve aparatus in the

cavity, of the moderator band in the RV and of the chordae tendinee and

papilary muscles in the left ventricle.

Similarly with the devices for ASD, many types of devices have ben

developed for treatment of VSD, adapted according to the specific location

of the defect (fig. 46): Amplatzer muscular, postmyocardial,

perimembranous, etc.

Rashkind Clamshell Amplzer muscular Amplatzer concentric Amplazer excentric

Fig. 45 - Closure devices for closure of ventricular septal deffects

64

All procedures for VSD closure are performed under general

anesthesia and with fluoroscopic and transesophageal or intracardiac

guidance. The VSD is crossed from the left side, and the left disk is

deployed in the left ventricular cavity, followed by retraction of the system,

control angiogram and final release of the device (fig. 46).

Fig. 46 - Closure of a VSD - Technique and echocardiogaphic control

3) Interventional closure of Patent Ductus Arteriosus

Patent ductus arteriosus has an incidence of approximatey 1 in 2.000

infants, representing 5-10% of all congenital heart diseases in children. The

clinical significance of a PDA are determined by size, length and age at

presentation.

The closure of a PDA is performed usually in general anesthesia in

children and in local anesthesia in adults.

Different devices are available for closing PDA, most commonly used

being modified Amplatzer (fig. 47), Rashkind or coil occluders (Gianturco

65

coils). Ducts smaller than 5 mm could be occluded with coil, but ducts

greater than 5 m in diameter are unsuitable for coil occlusion.

Technical challenges associated with coil occlusions are related to

crossing the duct, coil position and embolisation.

The accepted standard treatment of patients with Patent Ductus

Arteriosus is currently the transcatheter occlusion with one of the available

devices. However, in very small infants and preterm newborns, surgical

treatment is still the procedure of choice.

Fig. 47 - Closure device for closing Patent Ductus Arteriosus

4) Interventional closure of Left Atrial Appendage

Closure of LAA is required as atrial fibrillation is one of the most

frequent cardiac diseases and it frequently complicates with thrombus

formation in LAA. In turn, the LAA is the most common site of thrombus

development, which results in systemic thromboembolism.

Percutaneous closure of LAA presents an overall improved safety

profile compared to surgical closure or medical therapy. A number of

devices have been developed for this indication, including the Watchmann

and the Plaato devices (fig. 48), which have recently become available.

66

Prior to the procedure, the LAA should be evaluated by

transesophageal echocardiography in order to exclude the presence of

thrombus. If thrombus is present, the procedure should be postponed and

appropriate anticoagulation treatment should be initiated. Left atrial access is

gained using transseptal puncture and angiographic control from different

views is necessary for a complex evaluation of left atrial appendage

morphology. After the appropriate size is determined, the device is placed

into the LAA and deployed.

Watchman (nitinol) Plaato (nitinol covered with PTFE)

Fig. 48 - Devices for percutaneous closure of left atrial appendage

5) Percutaneous interventions in valvular heart diseases

Percutaneous intervention in mitral stenosis

Percutaneous treatment in mitral stenosis is recommended in selected

cases of mitral stenosis, in cases with anatomy suitable for balloon dilatation

(no valve fibrosis, no severe subvalvular stenosis, no sever associated mitral

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regurgication and no intraatrial thrombus. A transesophageal examin ation

should be performed before the procedure in order to assess all these

characteristic.

The technique for mitral valvuloplasty involves transeptal puncture

and placement of a special ballon (Inoue balloon) accros the mitral valve.

The Inoue balloon composed as nylon and rubber micromesh, is

selfpositioning and pressure expandable and is inflated once it reaches the

desired position (fig. 49). An alternative technique is represented by double

balloon technique, which uses a treoil balloon and a single balloon

positioned across the mitral valve (fig. 50). All the procedure is performed

under careful ECG and hemodynamic monitoring and at the end it may

require placement of an occluder disk at the site of atrial septum puncture.

a b

Fig. 49 - Mitral valvuloplasty - a) Inoue balloon b) double balloon technique

The most frequent complication is acute mitral insufficiency, followed

by embolism and haemopericardium related to transseptal catheterization.

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Transacatheter Aortic Valve Replacement

Transcatheter aortic valve replacement is gaining an increased role in

interventional cardiology. TAVI is currently indicated for high surgical risk

patients with symptomatic aortic valve stenosis requiring aortic valve

replacement.

The interventional aortic valve replacement is currently performed

using two main approaches:

-the apical antegrade approach, which involves puncture of the left

ventricle, being a hybrid procedure (surgical-percutaneous)

-the femoral approach (retrograde) involving introduction of the valve

system via the femoral puncture (fig. 51).

Regardless of the device used, the procedure requires general

anesthesia, temporary pacemaker implantation and careful monitorization.

Different valves have been tested and are being used for replacement

of aortic native valves: Edwards Sapient, Medtronic CoreValve, Lotus valve,

etc (fig. 52).

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Fig. 50 - transcatheter aortic valve replacement

Fig. 51 - different types of percutaneous aortic valves

Crossing the native calcified valve could be very challenging and

several special catheters and guidewires have been proposed as solutions,

offering different shapes and curve lengths adapted to the size of the annulus

and aortic root.

A pre-implant aortic balloon valvuloplasty is followed by prosthesis

positioning and development, using techniques that may vary according to

prosthesis type.

The procedure-related complications are: paravalvlar leak (fig. 52)

which can be recorded in as many as 70% of patients, depending largely on

the amount of valve calcification and the size of the aortic annulus,

conduction disturbances, cardiac arrhythmia, perforations and coronary

occlusions.

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Fig. 52 - Paravalvular leak

Interventional treatment for mitral regurgitation

Percutaneous treatment in mitral regurgitation consists mainly in two

techniques:

a) Mitral annulus reshape (indiect anuloplasty), technique which takes

advantage on the proximity of the mitral annulus to the coronary sinus. A

catheter is advanced into the coronary sinus and anchors in the distal and

proximal part, pushing the mitral annulus and reducing the size of the mitral

regurgitation (fig. 53a).

b) Mitral leaflet repair (mitral clips) uses a transseptal approach, after which

a guide catheter is positioned in relation to mitral regurgitation orifice and a

mitral clip is deployed (fig. 53b)

Fig. 53 - a) Mitral annulus reshape, b) mitral clip

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6). Percutaneous Left Ventricular reconstruction

Percutaneous left ventricular reconstruction is indicated in cases of

large ventricular aneurysms, usually following anterior myocardial

infarctions, and realizes exclusion of the aneurismal part of the left ventricle,

leading to a superior contractility and better outcome (fig. 54)

Fig. 54 - implantation of left ventricular parachute valve

7. Interventional treatement in Hypertrophic cardiomyopathy

Percutaneous treatment in hypertrophic cardiomyopathy is

recommended in cases of severe septal hypertrophy which realizes a

significant gradient in the left ventricular outflow tract (>30 mm Hg at rest

or >60 mm Hg after Valsalva maneuver, physiologic strass or post

extrasystole).

The technique, known as septl ablation, consists in injection of

alcohol into a septal artery (usually the first septal artery) and has been

proved to significantly reduce the hypertrophy and the gradient in the

outflow tract (fig. 55)

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The morphologic indications for septal ablation consist in:

-subaortic, SAM (systolic anterior movement) associated gradient

-mid-cavitary gradient

-exclusion of intrinsic mitral valve apparatus disease

-suitable septal branch at coronarography.

Fig. 55 - Alcohol septal ablation in hypertrophic cardiomyopathy.

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9. Interventional treatment in peripheral arterial diseases

The prevalence of Peripheral Arterial Disease increases with age,

reaching 3% at 40-59 years, 8% at 60-69 years and 9% over 70 years of

age.

The main techniques used in interventional treatment of peripheral

arterial diseases are:

-Balloon angioplasty

-Subintimal angioplasty

-Stenting (direct or provisional)

-Laser angioplasty

-Cutting balloon

-Atherectomy

-Crioaterectomy

1. Balloon angioplasty (Percutaneous Transluminal Angioplasty - PTA) is a

technique similar to the one described in coronary interventions, involving

passage of a balloon catheter across the lesion and inflation of the balloon

(fig. 56), thus realizing a complete compression of atheromatous plaque

against the vessel wall.

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Fig. 56 - Percutaneous Transluminal Angioplasty

The term subintimal angioplasty refers to passage of a wire within

the intima and inflation of the balloon in the space between the intima and

the rest of the vessel wall, creating a new healthy lumen (fig. 57)

Fig. 57 - subintimal angioplasty

Stenting in peripheral arteries is called direct stenting, when stentin g

is performed as first choice option, or provisional stenting, whent it is

performed only in case of suboptimal result on angioplasty (fig.58).

Conventional angioplasty

Subintimal angioplasty

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Fig. 58 - iliac stenting.

Opposite to coronary interventions, where almost in all the cases the

stents used are ballon-expandable stents, autoexpandable stents are much

more frequent used in peripheral interventions.

Results of the clinical trials proved that peripheral stenting is safe,

efficient and durable and has superior long-term results, compared with PTA,

being the elected treatment in majority of aortoiliac occlusive disease

Stent-grafts are a special type of peripheral stents used in case of

perforations of vessel wall during angioplasty. They consist in a classic stent

covered with PTFE membrane (fig. 59), and are placed using endovascular

route at the site of the rupture to prevent bleeding. It has been proved that

neointimal formation is more reduced in case of stent-grafts than with

classical stenting.

Fig. 59 - Peripheral stent grafts

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The concept of laser angioplasty has been introduced in the 80`s,

based on the concept of plaque ablation and atherosclerotic material

vaporization. Laser energy realizes a complete absorption of thrombus and

plaque, which is much higher compared with the effect on the arterial wall

and offers the possibility of selective elimination of plaque and thrombus

without injury on the vessel wall (fig. 60a). Using laser angioplasty, a

channel is created within the atherosclerotic material and the catheter is

advanced over the frontrunner guidewire step by step (fig. 60b)

a b

Fig. 60 -a) laser angioplasty b) step-by-step technique

Cutting ballons are conventional balloon catheter with vertical micro

blades, at the balloons surface, realizing 3-4 endovascular incisions during

dilatation (fig. 61).

Fig. 61 - Cutting balloon

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There are two types of atherectomy devices used in peripheral

interventions:

1. Extirpative atherectomy, or directional atherectomy, which

provides removal plaque and delivering it outside, using the Simpson

device/SilverHawk device (fig. 62).

2. Ablative, or Rotational Atherectomy, which fragments the plaque

into small particles that enter the reticuloendothelial system, using a

rotablator device.

Fig. 62 - excisional atherectomy

Crioballoons (PolarCath) are catheters with 2 balloons which use the

Nitrous oxide injection -10 Celsius degrees, leding to minimal neointimal

proliferation and cellular apoptosis induction.

Fig. 63 - Criocatheter

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Access route in peripheral interventions

The main access routes in peripheral interventions are (fig. 64):

1. Ipsilateral acces in majority of not technically-challenging cases

2. Cross-over, used mainly for:

-External Iliac Artery

-Distal Common Iliac Artery oclusions

Used in the majority of CTOs

3. Bilateral access, used mainly for:

-Proximal oclusion of Common Iliac Artery

-Contralateral access, antegrade passage, retrograde recanalization

4. Axillar acces, recommended mainly in case for bilateral occlusion of

Common Iliac Artery or External Iliac Artery

a b c

Fig. 64: a - controlateral acces; b - bil