STRESS PROTOCOLS..pptx imaging cardiac

stress

1. STRESS ECHOCARDIOGRAPHY PROTOCOLS BY DR ANOSHA KAMAL CARDIOLOGY FELLOW-YEAR 1

2. STRESS ECHOCARDIOGRAPHY SE is an effective method of detecting myocardial ischemia based on Stress indicated regional wall motion abnormality. It is based on principles outlined by the ischemic cascade. The goal is to determine whether ischemia is present or if there is baseline wall motion abnormalities then myocardium is viable or not.

3. Indications of Stress echocardiography CAD-Diagnosis/Viability/Prognosis Evaluation of dyspnea Mitral valve disease( Stenosis and regurgitations ) Aortic stenosis ( Asymptotic AS and low flow low gradient AS ) Pulmonary HTN LVOT/HOCM

4. Absolute contraindication Acute MI (within 2-4 days) High risk Unstable Angina Uncontrolled supraventricular or ventricular tachycardia BP systolic >200 and diastolic greater than 110 Severe symptomatic AS Uncontrolled Heart failure Acute PE /pulmonary infarct Acute myocarditis /peri carditis Acute aortic dissection

5. Relative contraindications Left main coronary artery Stenosis Moderate to Severe stenotic valvular disease Tachy or brady arrhythmias Mental impairment Physical impairment High degree AV block

6. Stress echocardiography It is very sensitive and specific test for diagnosis of underlying CAD SE is considered superior to ETT and comparable to myocardial perfusion scan Before performing stress Echocardiography , prior history of CAD and underlying valvular heart disease is necessary Rest Images taken before test and stress images after achieving desired heart rate ( Maximum heart rate is 85% ( 220- age) and atropine can be used if needed

7. Methodology Patients Preparation Equipment Performing the test

8. Patients preparation Written and informed consent Avoid heavy meals few hours before the test Anti- anginal medications depending upon indication Standard 12 lead ECG Connection Peripheral IV line

9. Equipment Echocardiographic machine with standard hemodynamic monitoring equipment is needed Resuscitation kit and defibrillator Treadmill machine Or bicycle machine Infusion pumps Software in echocardiographic machine to compare side by side rest vs stress images

10. STRESSORS Exercise Pharmacological Atrial pacing

11. Exercise protocols Treadmill exercise Upright Bicycle protocol Supine bicycle protocols

12. Treadmill or exercise stress Echocardiography( ESE/TSE)

13. Upright bicycle ergometer

14. BICYCLE ERGOMETRY Some laboratories perform stress echocardiography using supine or upright bicycle ergometry. A typical symptom-limited supine bicycle protocol starts at a workload of 25 watts and increases by 25 watt increments every three minutes until an endpoint is achieved.

15. Pharmacological stressors Dobutamine ( most widely used) Adenosine Dipyridamole

16. Dobutamine stress echocardiography ( DSE) MOA: potent synthetic catecholamine which has both strong positive inotropic and chronotropic effects. At lower doses increases myocardial contractility and cardiac output and heart rate at higher doses Dobutamine is administered via infusion pump with incremental doses every 3 minutes starting from 5 ug/kg/min then 10,15,20,30 and 40 until 85% heart rate ( age related ) is achieved ( atropine / moderate exercise can be used)

17. The plasma half-life of dobutamine is 2 minutes with the onset of action within 1 to 2 minutes; however, up to 10 minutes may be required to obtain the peak effect Antidote is inj: Esmolol 0.5 to 2mg/kg body weight over 1 mint Inj: metoprolol 2.5 to 5mg IV

18. The role of stress echo in detecting myocardial viability involves the demonstration of myocardial reserve Myocardial thickening is impaired when 20% or more wall is affected Therefore viability testing inform about the advantage of revasc. Dobutamine infusion protocol started from 2.5ug /kg/min with staged increase in dose 5,10, 20

19. Pacing stress echocardiography Patient with PPM during dobutamine stress echo may require device reprogramming in order to attain maximum heart rate The usual dobutamine increase 5, 10 and 20 if ventricular pacing at the end of 20ug/kg/min then dobutamine increased and PPM rate increased to 70% for 3 mints then 85% for 3 minutes then stress images are taken and now cool down period begin dobutamine stopped and PPM rate decreased to 70% then to the usual rate

20. Dipyridamole stress Echocardiography Alternative to dobutamine Coronary vasodilator Contraindications are 2 nd /3 rd degree heart block, severe bronchospasm, unstable CVD and hypotension Two protocols are use 1. dipyridamole 0.56mg/kg over 4 mints then no dose for 4 minutes then 0.28mg /kg over 2 mints and then atropine 0.25mg every mint up to 1mg if needed 2. 0.84mg/kg over 6 minutes with no atropine Aminophylline is an antidote

21. Absolute indications to terminate test Drop in systolic BP greater than 10mm from baseline despite increase in workload, if accompanied by other evidence of ischemia Limiting chest pain ( moderate to severe) Increase in CNS symptoms ( ataxia and near syncope) Signs of hypoperfusion ( Cyanosis and Pallor) Technical difficulties in monitoring Vitals and ECG Patients request Sustained Ventricular tachycardia ST elevation _>1mm in leads without Q waves ( other than V1/AVR) ST depression _> 3mm

22. Relative indication to terminate the test Drop in SBP > 10mm from baseline despite increase in workload but not accompanied by other evidence of ischemia STD > 2mm horizontal/down sloping or Marked axis deviation Multifocal non sustained VT /SVT or high degree AV block Fatigue /SOB/ leg cramps /wheezes/claudication SBP > 220 or DBP> 115

23. Interpretation LOW RISK : Less than 1.1 Intermediate : 1.1 to 1.6 High risk : 1.7 or greater

24. Example No of normal segments : 16 No of akinetic segments on peak stress : 4 Calculate WMSI WMS1: 4*3 + 12/16 WMSI: 24/16= 1.5 ( Intermediate risk study)

25. The common potential targets for Doppler examination following stress testing include Mitral valve – Changes in mitral stenosis gradient or mitral regurgitation quantity following stress Aortic valve – Evaluation of aortic valvular gradients in suspected low-flow, low-gradient aortic stenosis Tricuspid valve – Assessment of tricuspid regurgitation velocity for estimation of pulmonary artery systolic pressure in patients with suspected pulmonary hypertension Left ventricular outflow tract (LVOT) – Evaluation for inducible or worsening LVOT gradient in suspected or known hypertrophic cardiomyopathy

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