Stress echocardiography

Stress Echocardiography by Sruthi Meenaxshi

1. STRESS ECHOCARDIOGRAPHY Dr.Sruthi Meenaxshi MBBS,MD,PDF

2. STRESS ECHOCARDIOGRAPHY Stress Echocardiography enables evaluation of cardiac function at rest during pharmacologic stress, during or immediately following dynamic exercise. 

3. Stress echocardiography can be accomplished using either exercise (treadmill or bicycle) or pharmacologic agents (predominantly  dobutamine ) as the stress mechanism 

4.  Exercise two-dimensional (2D) imaging is used primarily to detect the presence and extent of coronary artery disease to detect regional ischemia resulting wall motion abnormalities.

5. exercise Doppler permits evaluation of valvular function pulmonary artery pressure left ventricular outflow tract gradients global ventricular systolic and diastolic function.

6. Echocardiographic contrast agents may be useful in enhancing endocardial border definition when two or more segments of the left ventricle are not well visualized.

7. INDICATIONS ●Evaluation of patients with known or suspected coronary artery disease. ●Assessment of myocardial viability ●Evaluation of dyspnea of possible cardiac origin ●Evaluation for pulmonary hypertension, as pulmonary artery systolic pressure can be estimated atrest and with exercise. ●Evaluation of mitral valve disease, including mitral stenosis and mitral regurgitation ●Evaluation of aortic stenosis . Stress echocardiography may be reasonable and helpful in patients with low gradient aortic stenosis or asymptomatic aortic stenosis . ( ●Evaluation of left ventricular outflow tract gradients, mitral regurgitation, and pulmonary hypertension in patients with hypertrophic cardiomyopathy .

8. CONTRAINDICATIONS Acute myocardial infarction (within two days) Ongoing unstable angina Uncontrolled arrhythmias with hemodynamic compromise Symptomatic severe valvular stenosis Decompensated heart failure Active endocarditis Acute myocarditis or pericarditis Acute aortic dissection Acute pulmonary embolism, pulmonary infarction, or deep venous thrombosis Physical disability that precludes safe and adequate testing

9. STRESS TECHNIQUES Protocols  — The practice guidelines from the American Society of Echocardiography (ASE) recommend symptom-limited exercise according to standard protocols using either a treadmill or bicycle These guidelines note that if evaluation of wall motion is the main purpose of the test, then treadmill exercise is usually used, whereas if stress Doppler information is desired, bicycle exercise should be considered because it enables Doppler as well as wall motion evaluation during each stage of exercise . As with any exercise stress test, exercise should be performed until the patient feels that he/she cannot exercise further due to fatigue or symptoms, although in some instances there may be appropriate endpoints determined by the provider or the protocol. 

10. The practice guidelines from the American Society of Echocardiography (ASE) recommend symptom-limited exercise according to standard protocols using either a treadmill or bicycle These guidelines note that if evaluation of wall motion is the main purpose of the tes t, then treadmill exercise is usually used, S tress Doppler information is desired, bicycle exercise should be considered because it enables Doppler as well as wall motion evaluation during each stage of exercise As with any exercise stress test, exercise should be performed until the patient feels that he/she cannot exercise further due to fatigue or symptoms, although in some instances there may be appropriate endpoints determined by the provider or the protocol.

11. EXERCISE ECHOCARDIOGRAPHY Exercise echocardiography is most commonly performed using a treadmill protocol Echocardiographic images are acquired prior to and immediately after completion of exercise . This method requires that the patient transfer from the treadmill into a recumbent position for imaging within a few seconds so that a complete set of images can be obtained as rapidly as possible, usually within 60 seconds after cessation of exercise. Use of digitized images permits review of multiple cardiac cycles, as well as side-by-side comparison of these images. This approach maximizes accuracy of interpretation. Continuous recording of images is also recommended as backup

12. For maximal diagnostic accuracy, images should be obtained prior to the heart rate decreasing toward baseline. Early image acquisition is necessary since ischemia-induced wall motion abnormalities may resolve rapidly as the heart rate slows , causing a decrease in the sensitivity of the test, especially for single vessel disease.

13. 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.

14. A major advantage of supine bicycle ergometry is that it allows continuous monitoring of wall motion during exercise . Imaging throughout the study may permit detection of the onset of wall motion abnormalities and improve sensitivity of detection of coronary artery disease. Moreover, acquisition of Doppler imaging during each stage of exercise is also feasible during supine bicycle exercise.

15. Supine Bicycle ergometer

16. Upright bicycle ergometer

17. PHARMACOLOGIC STRESS ECHOCARDIOGRAPHY Pharmacologic stress is employed in patients who are unable to perform exercise testing. myocardial viability assessment involves the administration of dobutamine with the addition of atropine as needed to achieve the target heart rate The American Society of Echocardiography guidelines recommend dobutamine as preferable to vasodilators ( eg , dipyridamole, adenosine .

18. DOBUTAMINE

19. Dobutamine Dobutamine is a direct-acting agent whose primary activity results from stimulation of the  β 1 -adrenoceptors  of the heart, increasing contractility and cardiac output. 

20. DOBUTAMINE STRESS ECHOCARDIOGRAPHY Graded dobutamine infusion in five three-minute stages starting at 5 mcg/kg/minute, followed by 10, 20, 30, and 40 mcg/kg/minute An initial dose of 2.5 mcg/kg/minute may be used in tests evaluating viability. Low-dose stages facilitate recognition of viability in segments with abnormal function at rest, even when viability evaluation is not the main focus of the test. Atropine , in divided doses of 0.5 mg to a total of 2.0 mg, should be administered as needed to achieve target heart rate. Atropine increases the sensitivity of dobutamine

21. During dobutamine echocardiography, echocardiographic images are acquired prior to the start of the dobutamine infusion, at the completion of each stage, and during recovery.

22. End point of the test The standard endpoint for dobutamine stress echocardiography is the achievement of target heart rate, defined as at least 85 percent of the age-predicted maximum heart rate. T he test may also be terminated following the development of significant symptoms, new or worsening wall motion abnormalities of moderate degree, significant arrhythmias, hypotension (systolic blood pressure less than 90 mmHg), or severe hypertension

23. VASODILATOR STRESS ECHOCARDIOGRAPHY Dipyridamole is administered at up to 0.84 mg/kg in two separate infusions: 0.56 mg/kg over four minutes ("standard dose"), followed by four minutes of no dose and Additional doses may be required in patients receiving beta blockers and those with single vessel disease . Some laboratories also use a sustained isometric hand grip or a low-level dynamic foot exercise (with or without atropine) in the late stages of the dobutamine protocol as a supplemental maneuver to achieve peak heart rate. 0.28 mg/kg is given over two minutes. If no endpoint is reached following the second infusion (total of 0.84 mg/kg), then atropine (doses of 0.25 mg, up to a maximum of 1 mg) may be administered

24. dipyridamole pyridamole  is a  nucleoside transport inhibitor  and a  PDE3 inhibitor   medication  that inhibits  blood clot  formation  when given chronically and causes  blood vessel dilation  when given at high doses over a short time.

25. Adenosine is typically infused at a maximum dose of 140 mcg/kg/minute over six minutes. Imaging is performed prior to and after starting adenosine infusion. Adenosine is a shorteracting agent employed for myocardial perfusion contrast echocardiography Vasodilator stress may be better suited for perfusion than wall motion analysis contraindicated in patients with reactive airway obstruction or significant conduction defects Not widely used

26. Temporary pacing Tachycardia induced by a pacemaker is an alternative to pharmacologic stress in patients who are not able to exercise. In selected patients with a permanent pacemaker, increasing the pacing rate to facilitate achievement of target heart rate may be used; this stress method is combined with dobutamine infusion Dobutamine is increased at a slower rate During recovery the pacing rate is progressively reduced at one-minute intervals .

27. HAND GRIP EXERCISE Handgrip exercise — Handgrip may be used as an adjunct to exercise or dobutamine stress echocardiography During the last stage of exercise or dobutamine infusion and 30 seconds before acquiring the peak exercise images, patients are asked to exert a sustained grip on a tennis ball. The hand grip response reliably raises blood pressure at least 10 mmHg and usually also increases heart rate

28. IMAGING TECHNIQUES Baseline echocardiography — screening assessment of ventricular function, chamber sizes, wall thicknesses, aortic root diameter, pericardial effusions, and gross valvular structure and Function estimate of pulmonary arterial systolic pressure using the tricuspid regurgitation velocity It also allows the diagnosis of ancillary conditions in the setting of coronary artery disease, such as intracavitary thrombus or ischemic mitral regurgitation .

29. 2D IMAGING To evaluate coronary artery disease Side by side comparsion of global and regional left ventricular systolic function at rest and after stress Pre peak and peak stress images are taken With stress the normal ventricle becomes hypercontractile , cavity size becomes small and ejection fraction increased

30. Function in each segment is graded (normal, hyperdynamic, hypokinetic, akinetic, dyskinetic, or aneurysmal) at rest and with stress. In addition, global left ventricular systolic function and cavity size are evaluated

31. 17 segment model

32. Detection of segmental left ventricular dysfunction is useful in diagnosing and localizing obstructive coronary artery disease The development of new or worsening segmental wall motion with stress suggests presence of hemodynamically significant coronary artery stenoses supplying the abnormal segments. Decrease of global left ventricular ejection fraction, and/or increased left ventricular end-systolic volume , suggest presence of severe obstructive coronary arterial disease such as flow-limiting left main stenosis or severe multivessel coronary artery disease

33. Doppler imaging Doppler echocardiography enables measurement of flow velocities and pressure gradients. Because Doppler recordings display instantaneous changes in these parameters, this is an excellent technique for the study of hemodynamic response to exercise or pharmacologic stress. Doppler examination following stress should be individualized based on the findings from the baseline (resting) echocardiogram as well as the indications for the study. :

34. 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

35. Use of Contrast agents Microbubble ultrasound contrast agents can enhance left ventricular endocardial border definition during stress echocardiography. Administered through IV access

36. Indications of echo contrast Enhances endocardial border and doppler signals Intravenous agitated saline is used Indicated in multiple coronary artery disease , abnormal baseline ecg , chronic lung disease, smoking , referral for dobutamine stress echocardiography, high body mass index

37. safety Safety of dobutamine administration — Dobutamine is generally safe and well tolerated when used in stress testing . Arrythmia , chest pain left ventricular obstruction can occur Minor arrythmia predominantly ventricular and premature atrial complex Atrial fibrillation , premature supraventricular complex Non sustained ventricular tacyarrthymias can occur