micha s. feinberg, md sackler school of medicine, tel aviv university 2007 aortic stenosis

Micha S. Feinberg, MD

Sackler School of Medicine,

Tel Aviv University

2007

Aortic StenosisAortic Stenosis

Aortic Stenosis

• The aortic valve maintains the anterograde flow of blood to the aorta when the valve is open and prevent retrograde flow into the left ventricle when the valve is closed.

• The normal aortic valve consists of three thin, mobile fibrous cusps that are covered by a layer of endothelium and attach to the aortic wall in a crescentic or semilunar manner.


• The most frequent valvular heart disease (~25%)• The most frequent cardiovascular disease after

hypertension and coronary artery disease in Europe and North America.

• Aortic stenosis is present in 1.3% of people aged 65–74 years and in 4% of people older than 85 years of age

• Aortic sclerosis; A degenerative disease of the aortic valve most likely represents an early stage of aortic stenosis. (> 65 years ~ 30%)

Aortic Stenosis - PrevalenceAortic Stenosis - Prevalence

• Calcific or degenerative AS has many similarities to atherosclerosis.

• The valvular lesions are characterized by intracellular and extracellular lipid accumulation and the presence of inflammatory cells, fibroblasts and mineralization.

• Calcification begins at the base of the cusps and progresses toward the edges, with the commissures remaining open.

Aortic StenosisAortic Stenosis - EtiologyAortic Stenosis - Etiology

Aortic Stenosis

• Among congenital anomalies, a bicuspid valve is the most common (2% of the population) associated with coarctation of the aorta and aortic dissection.

• Rheumatic aortic valve disease is characterized by commissural fusion with leaflet thickening and fibrosis. Uniformly accompanied by mitral valve disease

ETIOLOGIES OF OBSTRUCTION TO THE EJECTION OF BLOOD FROM THE LEFT

Valvular aortic stensis

Congenital:

Unicuspid valve

Bicuspid valve

Rheumatic

Degenerative (calcific):

Degenerative disease of tricuspid valve

Rare causes:

Homozigous type II hypercholesterolemia

Paget’s disease of bone

Renal failure

Radiation exposure

Aortic Stenosis - EtiologyAortic Stenosis - Etiology

Aortic Stenosis - EtiologyAortic Stenosis - Etiology

• Although each disease process that results in aortic stenosis causes specific changes, it may be difficult to distinguish a bicuspid valve from a trileaflet valve once severe calcific changes are present.

• Therapeutic options are the same for symptomatic patients with aortic stenosis regardless of the underlying cause.

Aortic StenosisAortic StenosisAortic Stenosis

Other Forms of Obstruction to Left Ventricular Outflow:

• Hypertrophic cardiomyopathy • Discrete congenital subvalvular aortic stenosis • Supravalvular aortic stenosis

Aortic Stenosis – Differential DiagnosisAortic Stenosis – Differential Diagnosis

• Resistance to flow by the AV imposes a pressure overload on the left ventricle.

• Slowly increasing pressure overload leads to increased thickness of the left ventricular walls (hypertrophy) so that the ratio of LV pressure to thickness remains constant, minimizing wall stress.

The law of Laplace :

Stress = Pressure x Radius

2 x Thickness

Aortic StenosisAortic Stenosis - PathophysiologyAortic Stenosis - Pathophysiology

The costs of this compensatory mechanism include:

• Reduced left ventricular compliance

• Increased myocardial oxygen demand

• Decreased coronary blood flow

• Eventual left ventricular systolic dysfunction.

Aortic StenosisAortic Stenosis - PathophysiologyAortic Stenosis - Pathophysiology

• Frequently a long latent period. • Diagnosis is often initially considered during a routine

physical examination when a systolic murmur is detected.

• In general symptoms can be attributed only to severe aortic stenosis.

Severe Aortic Stenosis = valve area <1.0 cm2 or 0.6 cm2/m2 body surface area

Aortic Stenosis – Clinical PresentationAortic Stenosis – Clinical Presentation

Aortic Stenosis – Clinical PresentationAortic Stenosis – Clinical Presentation

Severity MildModerateSevere

Jet velocity (m/sec)< 33 - 4> 4

Mean gradient (mmHg)< 2525 - 40> 40

Valve Area (cm2)1.5-2.01.0-1.5< 1.0

Valve area Index (cm2/BSA)

< 0.6

AHA/ACC Guidelines - 2006

– Angina pectoris– Syncope or presyncope– Congestive heart failure.

• Approximately 50% of patients with aortic stenosis have coronary artery disease to explain the development of angina.

• Syncope or presyncope is usually temporally related to exertion. It occurs when elevated left ventricular cavity pressure stimulates baroreceptors, which induces arterial hypotension, decreased venous return and occasionally bradycardia. Syncope at rest is more commonly the result of ventricular arrhythmias.

• Dyspnea is generally considered to occur late in the disease process and indicates more severe aortic stenosis.

Aortic Stenosis - SymptomsAortic Stenosis - Symptoms

Significant aortic stenosis include;

• Sustained apical impulse• Slow-rising and weak carotid pulse• Crescendo–decrescendo systolic murmur.

• Prolonged left ventricular ejection through the narrowed valve yields a slow-rising pulse (pulsus tardus); reduced stroke volume results in a weak or small amplitude pulse (pulsus parvus).

• The apical impulse is typically sustained but not displaced, reflecting prolonged left ventricular ejection.

Aortic Stenosis – Physical ExaminationAortic Stenosis – Physical Examination

• If the aortic valve leaflets are mobile, as in congenital aortic stenosis as opposed to degenerative aortic stenosis, an ejection click may be heard at the base.

• The second heart sound may be single because the aortic component is diminished as a result of calcification and stiffening of the valve leaflets.

A normal second heart sound implies normal valve closure and the absence of severe stenosis


• The crescendo–decrescendo systolic murmur is best heard over the ascending aortic in the second right intercostal space.

• Often well transmitted to the base of the neck and the carotid arteries.


• The murmur begins after isovolumetric contraction and ends before the second heart sound.

• Distinguish from mitral regurgitation, which begins immediately after the first heart sound and extends into second heart sound and frequently obscures it.

• As the severity of stenosis increases, the time to peak intensity of the murmur is further delayed


• Left ventricular hypertrophy may be seen as rounding of the cardiac apex.

• Poststenotic dilatation of the proximal aorta suggests stenosis at the valvular level.

• Aortic valve calcification occurs in the majority of patients who have significant stenosis.

Aortic Stenosis – Chest RadiographyAortic Stenosis – Chest Radiography

Aortic Stenosis – Chest X-RayAortic Stenosis – Chest X-Ray

Arrow – post stenotic dilatation

• The ECG often shows left ventricular hypertrophy with or without repolarization abnormalities (strain pattern). However, severe aortic stenosis can be present without ECG evidence of left ventricular hypertrophy.

• Left bundle branch block may be present. • Extensive calcification of the conduction system may

result in first-degree atrioventricular block and, rarely, complete heart block.

• A normal ECG can be seen in 10–20% of patients who have significant aortic stenosis.

Aortic Stenosis - ElectrocardiographyAortic Stenosis - Electrocardiography

Aortic Stenosis - ElectrocardiogramAortic Stenosis - Electrocardiogram

• Echocardiography has emerged as the principle method of establishing the diagnosis of aortic stenosis.

• Valve anatomy.

• Severity of stenosis.

• Other valvular or nonvalvular conditions.

• Left ventricular response to the pressure overload.• Requires special skill and expertise - investigator

dependent

Aortic Stenosis - EchocardiographyAortic Stenosis - Echocardiography

• Characteristics of degenerative (calcific) disease include;– increased echogenicity and reduced systolic opening– Commissural fusion and coexisting mitral valve

involvement are the distinguishing features of rheumatic aortic valve disease.

The severity of stenosis can be represented by:

• Aortic jet velocity

• Estimated maximum and mean transaortic pressure gradients

• Estimated aortic valve area

Aortic Stenosis – EchocardiographyAortic Stenosis – Echocardiography

Severity MildModerateSevere

Jet velocity (m/sec)< 33 - 4> 4

Mean gradient (mmHg)< 2525 - 40> 40

Valve Area (cm2)1.5-2.01.0-1.5< 1.0

Valve area Index (cm2/BSA)

< 0.6

AHA/ACC Guidelines - 2006


The pressure difference (gradient) that causes blood to flow between two chambers can be estimated using a modification of the Bernoulli equation:

Pressure difference P2 −P1 = (4 x Velocity of flow)2

P2 is the upstream pressure

P1 is the downstream pressure.

Aortic Stenosis - Aortic Stenosis - EchocardiographyEchocardiography

• The maximum gradient can be determined from the maximal velocity, and the mean gradient can be determined by integrating the instantaneous pressure gradients over the systolic ejection period.


Aortic Stenosis – Valve Area - Continuity Aortic Stenosis – Valve Area - Continuity PrinciplePrinciple

The stroke volume (SV) at the level of the aortic valve (AV) equals the stroke volume at the level of the left ventricle outflow tract (LVOT). The velocity time integral (VTI) is measured with pulsed Doppler in the outflow tract and with continuous wave Doppler in the narrowed orifice. The cross-sectional area (CSA) at the LVOT is measured on two-dimensional echocardiography, and the equation is solved for the CSA of the aortic valve. LA, left atrium; LV, left ventricle.

• Left ventricular hypertrophy may result in LV diastolic dysfunction, which can be evaluated by echocardiographic measurements.

• Echocardiography also allows evaluation of other potential causes of a systolic murmur, such as mitral regurgitation, hypertrophic cardiomyopathy, coarctation of the aorta and ventricular septal defect.

• A large number of patients (approximately 80%) who have aortic stenosis also have some degree of aortic regurgitation that should be quantified.


• Invasive measurements of the transaortic valve gradient and calculation of the aortic valve area by the Gorlin formula are needed when good-quality echocardiographic data are not available.

• Patients at risk of coronary artery disease require coronary angiography so that bypass grafting can be performed at the time of valve replacement.

Aortic Stenosis – Crdiac CatheterizationAortic Stenosis – Crdiac Catheterization

• The peak-to-peak gradient is the difference between the peak left ventricular pressure and the peak aortic pressure.

• The peak instantaneous gradient corresponds to the maximum gradient measured by Doppler echocardiographic methods.

• The mean gradient is average transaortic gradient during the systolic ejection period

Aortic Stenosis – Crdiac CatheterizationAortic Stenosis – Crdiac Catheterization

• An aortic root injection can be performed to determine the number of cusps and to assess for aortic regurgitation and poststenotic dilatation.

• To apply the Gorlin formula, the transaortic volume flow rate is measured by the thermodilution method or the Fick method or by left ventricular angiography.

AVA = 1000 x CO

44 x SEP x HR x (delta P)1/2

AVAAVA == Cardiac OutputCardiac Output

(delta P)(delta P)1/21/2

Aortic Stenosis – Cardiac CatheterizationAortic Stenosis – Cardiac Catheterization

Aortic Stenosis - MRIAortic Stenosis - MRI

• Stress testing is contraindicated in symptomatic patients who have aortic stenosis.

• It may be useful when the actual presence of symptoms is unclear or when symptoms appear to be out of proportion to the severity of the stenosis.

• Recent studies show that evaluating patients with minimal or no symptoms documented no serious complications, and a 10% occurrence of exertional hypotension, ST-segment depression and ventricular ectopy reprsenting a higher risk group.

Aortic Stenosis – Stress TestingAortic Stenosis – Stress Testing

ASYMPTOMATIC AORTIC STENOSIS

• The treatment of patients who have aortic stenosis is dictated by the presence or absence of symptoms.

• Asymptomatic patients should receive antibiotic prophylaxis for endocarditis. In addition, they should be provided with education regarding expected symptoms and the time course for disease progression.

Aortic Stenosis - ManagementAortic Stenosis - Management

• Modification of risk factors (hypertension, smoking, diabetes, elevated low-density lipoprotein cholesterol), should also be a major focus of treatment to prevent concurrent coronary artery disease.

• Statines and aortic stenosis– Several retrospective studies have

demonstrated that statin treatment is associated with lower haemodynamic progression of AS.

– Intensive lipid-lowering therapy did not halt the progression of calcific aortic stenosis or induce its regression (Small prospective randomized study,n=155, NEJM 2005).

– Final conclusions on the efficacy of statin treatment can, however, only be drawn from large prospective randomized controlled trials.


• Prospective studies have shown that the average rate of increase in maximum aortic jet velocity is 0.30.3m/s per year, with an increase in mean gradient of 77mmHg per year and a decrease in aortic valve area of 0.120.19cm2 per year.

• However, the rate of hemodynamic progression in an individual patient may be more variable.

Aortic Stenosis – ManagementAortic Stenosis – Management

Surgical considerations

• Operative mortality is ideally be in the range of 2–3%, however, it may be as high as 10% in the elderly and even higher in the presence of significant co-morbidity.

• Prosthetic valve related long term morbidity and mortality must be taken into account. Thromboembolism, bleeding, endocarditis, valve thrombosis, paravalvar regurgitation, and valve failure occur at the rate of at least 2–3% per year.


Risk stratification by echocardiography– Peak aortic jet velocity and LV ejection

fraction as well as the rate of hemodynamic progression have been identified as independent predictors of outcome (retrospective).

– Aortic valve calcification has turned out to be a powerful independent predictor of outcome.

– The combination of a notably calcified valve with a rapid increase in velocity of > 0.3 m/s from one to the following visit within one year has been shown to identify a high risk group of patients. Approximately 80% of them required surgery or died within two years

Aortic Stenosis – Risk StratificationAortic Stenosis – Risk Stratification

Risk stratification by exercise testing • Exercise testing is primarily helpful in

physically active patients younger than 70 years and A normal exercise test indicates a very low likelihood of symptom development within 12 months

Aortic Stenosis – Risk StratificationAortic Stenosis – Risk Stratification

–Symptom development on exercise testing in physically active patients younger than 70 years indicates a very high likelihood of symptom development within 12 months and valve replacement should be recommended.

SYMPTOMATIC AORTIC STENOSIS

• The prognosis of symptomatic patients is extremely poor without surgical treatment.

• In recent studies, symptomatic patients with aortic stenosis who have refused surgery have had 5-year survival rates of only 15–50%.

• Options for valve replacement include the pulmonary autograft procedure, bioprosthesis and mechanical valves and recently percutaneous aortic valve replacement.


CoreValve prosthesisCoreValve prosthesis

Percutaneous AVRPercutaneous AVR

The balloon-expandable prosthesis (Cribier

Edwards)

• Stainless steel stent with an attached equine pericardial trileaflet valve and fabric sealing cuff (Two sizes: 23- and 26-mm).


Trans-apical Edwards SAPIEN THVTrans-apical Edwards SAPIEN THV


http://circ.ahajournals.org/content/vol116/11_suppl/images/large/35FF2.jpeg

Guidelines AHA ACC/ EuropeanGuidelines AHA ACC/ European Eur

2007

AHA/ACC 2006

II סימפטומטית וקשההיצרות

II פגיעה בחדר עם קשההיצרותשמאל

II מתוכנן , בחולה קשההיצרות לב לניתוח

)מסתם/מעקפים/האורטה העולה(

IIIb לכאורה קשההיצרות ,לסימפטומטי אסימפטומטי, הופך

במאמץ

IIaIIa מתוכנן בחולה,בינוניתהיצרות לניתוח לב

)מסתם/מעקפים/האורטה העולה(

micha s. feinberg, md sackler school of medicine, tel aviv university 2007 aortic stenosis

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