recurrent intra operative st depression treated by phenyl ephrine

7/28/2019 Recurrent Intra Operative ST Depression Treated by Phenyl Ephrine

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Recurrent intraoperative silent ST depression

responding to phenylephrine

-Rajkumar S Guide: Dr. Indira mam


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An unusual case of recurrent, symptomless

inferior wall ischemia in an apparentlyhealthy male with no history of coronary

artery disease after a spinal block and its

successful management

Case Report


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A 46-year-old, 72 kg, man was scheduled for elective

right knee replacement for post traumatic osteoarthritis.

No other significant present history

Past history Known hypertensive, well controlled on oral

amlodipine 5 mg OD.

Exercise tolerance mildly restricted since last 2

years due to pain associated with osteo arthritis, taking

occaional NSAIDS. No H/O angina, palpitaion, diaphoresis.

History


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Hemoglobin was 12.3 mg%

Biochemical profile / lipid profile were normal

CXR / ECG showed no abnormality

Intermediate risk was explained to the patient and a

written informed consent was taken.

Advised to remain NPO from midnight and 2 units ofpacked cells were arranged.

Pre OP


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Standard monitoring was

connected which showed ECGwith normal sinus rhythm with

HR 74/ min, BP was 116/ 70

mm/Hg

Saturation was 100% on room

airA 16 G IV line was secured


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Your own footer Your Logo

CSE block was given in right

lateral position with 12.5 mg of 0.5

% hyperbaric bupivacaine alongwith 25 mcg fentanyl was given

intrathecally through L3- L4

interspace

18G catheter was threaded into

the space and fixed to skinPatient was turned to supine

position and sensory level of block

was found to have reached around

T5 after 10 min.


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Progressed to 3.4 mm in the next 5 minutes in the lead II alone.

Later it showed a value of +0.2 and +1.2 in lead V5 and aVL

respectively.

After 15 min, the ecg started to show down sloping ST depression

In the diagnostic mode monitor recognized the a ST depression of 2 mm

Patient was asked for any chest pain or heaviness which the patient

denied.

Intra op events

1

2

3

4

5

6

BP was 106/62 with HR 117 / min


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Since ECG pattern indicative of inferior wall ischemia

and there was increasing tachycardia, besides

augumenting fluids vasopressor was decided to use.

Phenyl ephrine 75 mcg bolus was given IV.

Pattern changed to normal, HR dropped to 100 / min and

BP picked up to 127/ 74 in next 5 minutes.

Diagnosis of ischemia remained uncertain as the lowest

BP was 106/ 62 mm / Hg.

? Ischemia


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Image just after 1stdose of phenylephrine


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After 10 minutes ST depression of 3.2 mm in

lead II with reciprocal ST elevation in aVL of

+1.1 mm was seen.

BP dropped to 101/ 59 mm / Hg with HR 110 /

min

Another phenyl ephrine bolus of 75 mcg wasgiven IV rhythm returned to normal in 5 minutes.

Till now patient received 1 litre of crystalloid and

500 ml of colloid.


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Image after normalization of ST segment


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A similar episode reoccurred over next 20

minutes and a phenylephrine infusion wasstarted @ 50 mcg/min

ST segment values became normal

HR became 84 / min

Surgeon was asked to withhold surgery after 2nd

episode as blood loss could precipitate MI

Surgery was deferred


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Renormalization after phenylephrine


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Quantitative assay of troponins were sent

immediately, A qualitative troponin after 4 hours

Both of which turned out to be negative for MI.

Cardiology evaluation later revealed a 70 %

occlusion of RCA.

An elective coronary stenting was done

subsequently.

Post op

PCI

Angiography

Troponins

Negative


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Coronary perfusion

pressure =

aortic diastolic pressure

left ventricular end

diastolic pressure


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Your own sub headline

Administering nitrates in this case may have aggravated

the tachycardia and increased myocardial workload.

Short acting beta-blockers are recommended to control

this tachycardia but they did not administer it as the bloodpressure was falling.

Pathophysiology of intraoperative MI is different than commonly seen ST

depression MI where plaque instability is the cause of ischemia.

Intraoperative MI is more of a demand-supply failure and hence the

treatment lines are different as well

Why Phenyl ephrine?


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Your own sub headlineTemplates

Phenylephrine preferentially acts on arterial alpha-receptors as

compared to venous. This is a potential disadvantage for a diseased

heart as it would increase afterload and increase cardiac oxygen

demand.

- Phenylephrine is a directly acting pure alpha 1

agonist which not only increases the blood

pressure but also lowers the heart rate and thus

was the drug of our choice in the given situation.- Ischemia is often associated with hypotension

that lowers cardiac perfusion pressure for a

normal heart.


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- A prolonged ST depression of >20-30 min or a

cumulative duration 1-2 h can lead to MI.

- Our patient showed three episodes ofsignificant ST depression but the duration of each

was limited to less than 10 minutes and hence did

not lead to a MI.

Why it didnt progress to infarction


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Patient felt no chest pain or heaviness..

The spinal block given to the patient may beresponsible for obscuring the manifestations of

ischemic pain.

The highest sensory block noted was up to T5;

the autonomic block may have been higher dueto differential blockade and involving the

cardiac sympathetic plexus T1-T4.

Absence of symptoms..


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When demand exceeds

supply

Inadequete myocardial oxygenation

leading to accumulation of anaerobic

metabolites

Myocardial infarction is defined as the death of

myocardial myocytes due to prolonged ischemia

Ischemia Discussion..

Death of

Myocytes

Toxic

metabolites

Ischemia


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In patients without previous history of coronary artery

disease (CAD), the incidence of perioperative myocardial

infarction (PMI) amounts to 0.6%

Most often the intraoperative cardiac ischemia involves

the left coronary artery and presents as ST segment

depression in the left sided leads

Ischemia Discussion..


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?

1) Down sloping ST

segmentdepression

2) More than 1.5 mm

3) Reciprocal lead

involvement

4) Associated withsymptoms / signs

Specific ST segment elevationNon specific ST elevation

1) Up sloping ST segment

depression

2) lower than 1.5 mm

3) No reciprocal lead

involvement


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Long-term mortality is higher

Frequently Non-Q wave

50% SILENT! Perioperative ischemia (esp prolonged) is

associated with adverse cardiac events.

Real-time detection may allow therapeutic

intervention.

Ischemia duration strongly associated with

peak cTn-I level (concept of troponin leak)

Ischemia preceded in all cases by heart rate

increase

Are perimyocardial ischemia different?


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Clinical predictors


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History angina, recent or past MI, HF, symptomatic arrhythmias,presence of pacemaker or ICD

Physical Examination general appearance, rales, elevated JVP,carotid and other arterial pulses, S3 gallop, murmurs

Comorbid Diseases

Pulmonary

Diabetes Mellitus

Renal Impairment

Hematologic Disorders

Ancillary Studies - ECG almost always indicated, blood chemistriesand chest X-ray based on history and physical findings

General Approach to the Patient


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Remote MI ( >1

month)

Stable angina

Compensated

CHF

Creatinine 2.0

Diabetes

IntermediateMajor Low

-Acute or recent

MI (< one month)

-Unstable orsevere angina

-Large ischemic

burden (stress

testing)-Decompensated

CHF

-Significant

arrhythmias

Clinical Predictors of Increased cardiac morbidity in

perioperative period

-Advanced Age.

-Abnormal ECG.

Rhythm other

than sinus.

-Low functional

capacity.

-History of

stroke.

-Uncontrolledsystemic

hypertension


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Intraperitoneal, Intrathoracic, Suprainguinal vascular procedures

0 predictors = 0.4%, 1 predictor = 1%, 2 predictors = 2.4%, 3

predictors = 5.4%

Hx of heart failure

DM requiring insulin

H of ischemic heart disease

Hx of cerebrovascular disease

Preoperative serum creatinine > 2.0 mg/dL

Independent predictors of major Perioperative cardiac

complications:

Revised Goldman Cardiac Risk Index

1

2

3

4

5

6

7


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-Intraperitoneal

/intrathoracic

-Orthopedic

-Head & neck

-Carotid

endarterectomy

-Prostrate surgery

Intermediate (1-5%)High risk ( > 5% )

-Endoscopic

-Breast

-Skin

-Cataracts

-Superficialprocedures

Low risk (


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Supplemental

Preoperative Evaluation

Noninvasive testing in preoperative patients indicated if 2 or more of

following present:

Intermediate clinical predictors (Canadian Class I or II angina, prior

MI based on history or pathological Q waves, compensated or prior

HF, or diabetes)

Poor functional capacity (


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Importance of exercise tolerance


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Pathophysiology ofperioperative Cardiac

Ischemia


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Unstable plaque / CAD

LVH

Hypercoagulable state and thrombosis

Catecholamines Pain / stimulus

anemia

Depth of anesthesia

BP swings pain

anemia/HYPOVOLEMIA ( neuraxial block, blood loss, venous return

compression, release of tourniquet )

Intraop factors


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Symptoms: usually none Pain, shortness of breath, sweating, nausea and

vomiting, altered mentation Clinical signs: usually none

Sweating, CHF, HR changes, arrhythmias,hypotension

ECG: key perioperative monitor

Pulmonary artery catheter Increased PCWP, new V waves on PCWP tracing

TEE SWMA, change in mitral regurgitation, diastolic

dysfunction, decrease in global contractility

How to Monitor for Ischemia


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Lead selection II and V4 or V5

ST SEGMENT CHANGES (most specific)

T wave changes

esp inversion in high risk groups

Arrhythmias

New conduction abnormalities

New atrioventricular block

Heart rate changes

ECG Monitoring for Ischemia


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ECG


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ECG

Depression: subendocardial ischemia,

poor localization Horizontal / downsloping depression >

0.1 mV (1 mm) at 60-80 msec after Jpoint

Upsloping depression > 0.15 mV at 80

msec after J point

Elevation: transmural ischemia, good

localization> 0.1 mV


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Conduction disturbances

R wave amplitude changes

Hyperventilation Electrolyte changes, hypoglycemia

Hypothermia (< 30)

Body position changes / retractors

Autonomic NS changes e.g. spinal Myocardial infarction or contusion

Neurological changes (trauma, SAH)

Acute pericarditis

ECG monitoring for Ischemia

Other Causes of Acute ST Segment Changes


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TEE is a highly sensitive for monitoring ischemia

In the event of ischemia there is development of new

regional wall motion abnormalities decreased systolic wall thickening

ventricular dilation

It can detect ischemia much earlier than ecg.

Limitations

Pre-intubation events are missed

Image plane may miss events in other areas of the

myocardium

TEE


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Myocardial ischemia reduces left ventricular compliance

that results in increased pulmonary artery occlusion

pressure and presence of V waves. impaired systolic function can lead to decreased cardiac

output which can be detected.

PCWP > 18-20 mm Hg

Limitations:

It is not sensitive for myocardial ischemia

Pulmonary artery cathetrisation may lead to increased

morbidity

Pulmonary artery catheter


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Hypotension along with decreasing

cardiac output can result from either1) hypovolemia

2) ventricular dysfunction

Measurement of stroke volume variationcan rule out hypovolemia

Arterial pressure waveform

analysis


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Arterial wave form

Hypotension along with

decreasing cardiac output

can result from either1) hypovolemia

2) ventricular dysfunction

Measurement of stroke

volume variation can rule out

hypovolemia


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Your own sub headline

Systolic pressure variation (SPV)

particularly increased D down, indicates

hypovolemia.

The greatest clinical use of systolic

pressure variation has been in the early

diagnosis of hypovolemia.

If we can rule out hypovolemia, systolic dysfunctioncan be diagnosed


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MI may be best detected with cardiac Troponin T

concentrations.

TnT and TnI levels may rise more than 20 times

above the reference range within 3 hrs after onset of

chest pain and may persist for up to 10-14 days

CPK-MB is not useful intraoperatively because the

leakage of these enzymes into the circulation canoccur 8-24 hours after an MI.

CD40 ligand - marker for platelet-monocyte

aggregation as thrombus is being formed

Markers


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Monitoring for ischemia


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Pre op procedures

PCI

CABG B blockers

Alpha-2 Agonist (Mivazerol, Dexmedetomidine,

Clonidine)

Statins Control BP

Antiplatelets and anti coagulants (if indicated)

Prophylactic placement of intra-aortic balloon

counterpulsation device

Management (prevention)


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Reduced

Hemodynamic

Stress

??? Platelet

Action

??? Metabolic

Increased

Diastole

Improved myocardial blood flow

Decreased

Ventricular

Arrhythmias

Reduced VF threshold

Spectrum of

potential

benefits of

beta-blockade

Spectrum of

potential

benefits of

beta-blockade

Plaque

stabilization

Antiarrhythmic

action

Improved oxygen

supply/demand


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Management of Suspected Intraoperative

Ischemia

FIRSTLY Secure system ensure adequate oxygenation, BP, volume, Hb

SECONDLY Optimize hemodynamics - especially tachycardia and blood

pressure

THIRDLY, consider Increase FiO2

NTG

Increased monitoring CVP, PCWP, TEE

Inform surgeon, alter surgical plan

Postoperative management


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Management of Suspected Intraoperative

Ischemia

Check ECG (calibration, mode, previous ECGprintouts)

Verify automatic ST segment analyses Look for associated features

Arrhythmias, hypotension

Increased filling pressures or new V waves

TEE changes (check all LV segments) Consider

Other causes of ECG change

Patients risk of CAD


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Deepen anesthesia

IV -blockadeEsmolol, 20100 mg, 50200 g/kg/min

Metoprolol, 0.52.5 mg

Labetalol, 2.510 mg IV nitroglycerin Nitroglycerin,

33330 g/min

Hypertension, tacycardia


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Ensure adequate anesthesia

Change anesthetic regimen

IV -blockade

Normotension tachycardia


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Deepen anesthesia

IV nitroglycerin or

Nicardipine, 15 mg, 110 g/kg/min

Hypertension, normal heart rate


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IV -agonist Phenylephrine, 25100 g

Norepinephrine, 24 g

Alter anesthetic regimen (e.g., lighten)

IV nitroglycerin when normotensive

Hypotension, tachycardia


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Lighten anesthesia

IV ephedrine Ephedrine, 510 mg

IV epinephrine Epinephrine, 48 g

IV atropine Atropine, 0.30.6 mg

IV nitroglycerin when normotensive

Hypotension, bradycardia


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IV Nitroglycerin

IV Nicardipine,

No hemodynamic abnormalites


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The Buffington ratio is a useful index. It

stipulates that patients suffering fromcoronary stenosis are at particular risk of

myocardial ischemia when their mean

arterial pressure is less than the heart rate(MAP/heart rate


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g

Ischemia Persists with Optimal

Hemodynamic

Keep increasing NTG (may combine with vasopressor ifhypotension)

May increase monitoring CVP, PCWP, TEE

CONSIDER Acute Coronary Syndrome (unstable angina,infarct) Aspirin or ketorolac

Heparin (5000 U bolus, then 1000 U/hr) if surgery permits

beta-blockade (aspirin & beta-blockade reduce risk of infarct andmortality)

Observe for complications- arrhythmias, CHF, infarct

Cardiology consult - urgent reperfusion - within 12-24 hours(especially if persistent ST segment elevation)

PTCA most practical (thrombolysis CI after surgery)

? IABP

P t ti M t f P i ti


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Postoperative Management of Perioperative

Ischemia

CONSIDER

ICU or CCU postop and/or cardiology referral

Surveillance for periop MI ECG immediately postop and on day 1 and 2

Cardiac troponin at 24 hrs and day 4 (or hosp

discharge) (CK-MB of limited use)

LONG TERM cardiologist

Risk factor management

Aspirin, statins, beta-blockade, ACE inhibitors


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In Greek mythology, the night has twin sons, Thanatos (death)

and Hypnos (sleep), who carry flaming torches pointing toward

the floor, to light a path through the dark

Juan Marin placed a small light between Thanatos and Hypnos

indicating the flame of life the anesthesiologist must guard.

The upper half of the emblem shows the rising or setting sun of

consciousness.

recurrent intra operative st depression treated by phenyl ephrine

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