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STRESS ECHO DEEPAK NANDAN Slide 2 Stress echo is a family of examinations in which 2D echocardiographic monitoring is undertaken before, during & after cardiovascular stress Cardiovascular stress exercise pharmacological agents Stress echo is a family of examinations in which 2D echocardiographic monitoring is undertaken before, during & after cardiovascular stress Cardiovascular stress exercise pharmacological agents Slide 3 PHYSIOLOGY Coronary blood flow pulsatile & phasic Precapillary arterioles resistance vessels * principal contributor of resistance * main controller of coronary blood flow CBF on demand occurs through reduction in resistance at this level Slide 4 CORONARY BLOOD FLOW RESERVE Maximal CBF / basal CBF Magnitude of bf secondary to any stress relative to resting flow In discrete stenosis CFR begins to when stenosis reaches 50% dm CFR is abolished when stenosis reaches 90% Resting bf remains constant up to 85- 90% of the stenosis Slide 5 Cellular Mechanism of Ischemia Consequence(s) of Mechanical Dysfunction Mechanical Dysfunction Abnormal Contraction and Relaxation Diastolic Tension Diastolic Tension O 2 Consumption (to maintain tonic contraction) ATP Hydrolysis Diastolic Wall Tension (Stiffness) O 2 Demand O 2 Supply Extravascular Compression Blood Flow to Microcirculation ( O 2 delivery to Myocytes) Modified from: Belardinelli et al. Eur Heart 8 (Suppl. A):A10-A13, 2006 Slide 6 Slide 7 BASIC PRINCIPLES OF STRESS ECHO BASIC PRINCIPLES OF STRESS ECHO Cardiac work load - O2 demands- demand supply mismatch- ischemia Impairment of myocardial thickening and endocardial motion Slide 8 Slide 9 Treadmill protocol Slide 10 Stress echo-Standard-format Slide 11 Supine bicycle ergometry Slide 12 Slide 13 Supine bicycle standard format Supine bicycle standard format Slide 14 Treadmill vs supine bicycle advantage Add information Wide spread availability Simple protocol High work load > Sensitive Disadvantage Imaging post ex only advantage Add information Wide spread availability Simple protocol High work load > Sensitive Disadvantage Imaging post ex only Advantage Image through out the exercise- peak Onset of RWMA Better image quality Contrast stress echo > Specific Disadvantage Lower work load Supine position affects ex.physio Advantage Image through out the exercise- peak Onset of RWMA Better image quality Contrast stress echo > Specific Disadvantage Lower work load Supine position affects ex.physio Slide 15 Information obtained from Exercise Stress but not available with Pharmacological Test Exercise Duration/Tolerance Reproducibility of Symptoms with Activity Heart rate response to exercise Blood Pressure response Detection of Stress Induced Arrhythmias Assess control of angina with medical therapy Prognosis Slide 16 Indication pharmacological stress echocardiography Inadequate exercise Left bundle branch block Paced ventricular rhythm pre-excitation or conduction abnormality Medication: beta-blocker, calcium channel blocker Evaluation of patients very early after MI( Exercise preferred-add information > sensitive in CAD compared to dobutamine Treadmill >sensitive, Bicycle>specific Bicycle during stress-> accurate presence and extend of dis vs pat choice,availability etc. Dobutamine is limited to pats who cant exert adequately & when the Q of viability is addressed In pharmaclogical stress dobutamine is the agent- produces true ischemia than a flow mismatch Slide 34 INTERPRETATION OF STRESS ECHO Subjective assessment of regional wall motion Compares wall thickening & endocardial excursion at baseline and stress Limitation- subjective & nonquantitative Measures like EF, ESV change, and strain rate to overcome limitations Slide 35 Strain rate-myocardial velocity gradient -postsystolic shortening Strain rate-myocardial velocity gradient -postsystolic shortening TDI/Strain imaging> sensitive Ischemia delays onset & rate of regional myo relaxation Time quantified using TDI QRS-onset of relaxation-350-400ms Interval by 34+/_10% in nl segments in response to high dose dopamine in interval is Grade 1-normal 2-hypokinesis 3-akinesis 4-dyskinesis Nl WMSI-1 at baseline and stress Any score>1-abnormal Good prognostic value Slide 38 Hypokinesia-specific in multivessel dis & in LAD than RCA/LCX Slide 39 Slide 40 Normal- hyperkinesis during stress test Normal- hyperkinesis during stress test Slide 41 DYSKINESIA OF THE APEX IN STRESS DYSKINESIA OF THE APEX IN STRESS Slide 42 Slide 43 Prognostic value A new wall motion abnormality,rest & exercise WMSI,ESV response-correlated with risk Slide 44 Chamber dilatation in resp to stress Chamber dilatation in resp to stress Slide 45 Prognostic value of stress echo Prognostic value of stress echo Independent predictors of cardiac events a)WMSI with exercise b) ST 1 mm c) treadmill time Risk Index(RI)=1.02(WMSI)+1.04(ST change) 0.14(Treadmilltime) RI in upper quartile(+0.66 to+2.02) risk was highest(30%) Prognostic value is comparable in women and men Slide 46 Stress echo after revascularisation Stress echo after revascularisation Slide 47 PRE-OPERATIVE RISK STRATIFICATION WITH DOBUTAMINE STRESS ECHO *Mayo Clinic, 530 Patients Slide 48 Perioperative marker of coronary event patients with a positive electrocardiographic response to treadmill stress test but no inducible wall motion abnormality on stress echocardiogram have a very low rate of adverse cardiovascular events during follow-up Slide 49 VIABILITY OF MYOCARDIUM VIABILITY OF MYOCARDIUM That has the potential for functional recovery;- either stunned/hibernating myocardium >6mm thickness -viable segment Stunned or hibernating improved contractility with dobutamine, not in infarcted myocardium Biphasic response low dose contractility(10 to 20 mcg/kg), at higher dose CBF -- contractility Slide 50 Biphasic response is the most predictive of the functional recovery after revascularisation Sustained improvement/no change-nonviable For viability assessment nuclear techniques are more sensitive dobut stress echo more specific PPV-similar NPV- favours dobut stress echo Slide 51 Myocardial viability-Biphasic response Myocardial viability-Biphasic response Slide 52 Sensitivity and specificity of exercise and pharmacologic stress test Sensitivity(%) Specificity(%) Dobutamine 71 96 66 - 83 Dipyridamole 43 74 92 - 100 Exercise 74 97 64 - 88 Slide 53 Advantages of Stress Echocardiography Compared to Nuclear Stress Testing Higher Specificity Visualization of cardiac valves Evaluate for presence of pericardial effusion Ability to measure RV Systolic Pressure More accurate assessment of LV ejection fraction Doppler interrogation to determine Diastolic Function Lower Cost Lack of Radiation Exposure Slide 54 Sensitivity Comparison of Different Testing Modalities Slide 55 Situations Where Stress Echo Preferred Situations Where Stress Echo Preferred Younger patients with lower likelihood of symptomatic coronary artery disease Pericardial Disease suspected Valvular heart disease needs to also be evaluated Need to evaluate for pulmonary hypertension Exertional dyspnea is the predominant complaint Slide 56 Thank you