Stress echocardiogram (stress echo heart test): procedure and ultrasound cost in USA

Medically reviewed: 20, December 2023

Read Time:8 Minute

Stress echocardiography is a non-invasive diagnostic test that uses ultrasound imaging to evaluate the heart’s function and blood flow under physical stress.

What is Stress Echocardiography procedure?

Stress echocardiography is a diagnostic tool that plays a significant role in assessing the existence and seriousness of coronary artery disease, along with determining the prognosis and treatment alternatives for individuals with diverse cardiac ailments. Within this article, we will delve into the fundamental principles, indications, protocols, interpretation, and constraints associated with stress echocardiography.

Principles of stress echocardiography

Stress echocardiography is based on the concept that myocardial ischemia, or reduced blood flow to the heart muscle, causes various regional changes in the contraction and relaxation of the heart wall. These changes can be detected by ultrasound imaging, which uses high-frequency sound waves to create images of the heart’s structure and motion. By comparing the images of the heart at rest and during or after exercise, the presence and location of ischemia can be determined.

Types of Stress echocardiography

Stress echocardiography can be performed with different types of stressors, such as exercise, pharmacological agents, or pacing. The choice of stressor depends on the patient’s clinical condition, ability to exercise, and availability of equipment. The most common stressors are:

Exercise stress echocardiography

This involves exercising on a treadmill or a stationary bike while the heart rate and blood pressure are monitored. The exercise intensity is gradually increased according to a standardized protocol until the target heart rate is reached or the patient develops symptoms or signs of ischemia. The ultrasound images are obtained either during the exercise (on-treadmill or on-bike approach) or immediately after the exercise (post-treadmill or post-bike approach).

Pharmacological stress echocardiography

This involves administering a drug that increases the heart’s oxygen demand or decreases its oxygen supply, simulating the effects of exercise. The most commonly used drugs are dobutamine, which stimulates the heart to beat faster and stronger, and dipyridamole or adenosine, which dilate the coronary arteries and cause a redistribution of blood flow away from the ischemic areas. The ultrasound images are obtained at baseline and at peak stress, usually with the addition of a contrast agent to enhance the image quality.

Pacing stress echocardiography

This involves implanting a temporary pacemaker in the right ventricle and increasing the pacing rate to induce stress. This method is mainly used for patients who have a permanent pacemaker or an implantable cardioverter-defibrillator and cannot undergo exercise or pharmacological stress testing. The ultrasound images are obtained at baseline and at peak stress.

Indications for stress echocardiography

Stress echocardiography is indicated for the diagnosis and management of patients with suspected or known coronary artery disease, and evaluation of other heart conditions such as valvular heart disease, cardiomyopathies, and congenital heart disease.

Stress echocardiography is a diagnostic procedure that is highly effective in determining if a patient is experiencing myocardial ischemia, a condition characterized by reduced blood flow to the heart muscle. This test is particularly helpful for individuals who are experiencing chest pain, difficulty breathing, or other symptoms that may indicate the presence of coronary artery disease.

Additionally, stress echocardiography also provides valuable insights into the functional significance of coronary stenoses, which are blockages or narrowings in the coronary arteries, that have been identified through angiography or other imaging techniques.

Risk stratification and prognosis

Stress echocardiography offers valuable insights into the future outcomes of patients who are either already diagnosed with or suspected to have coronary artery disease.

This diagnostic method considers the number, positioning, and severity of ischemic segments, allowing healthcare professionals to make informed predictions regarding the patients’ prognosis, as well as the presence of other factors, such as left ventricular dysfunction, wall motion abnormalities at rest, or ischemic mitral regurgitation. It can also help to guide the decision for revascularization or medical therapy in patients with stable or unstable angina, acute myocardial infarction, or prior revascularization.

  • Evaluation of myocardial viability:

Stress echocardiography can assess the presence and extent of viable myocardium in patients with chronic ischemic cardiomyopathy, defined as the potential for recovery of function after revascularization. This can be done by using low-dose dobutamine, which can induce a biphasic response of the dysfunctional segments: an improvement of contraction at low doses, indicating viability, and a worsening of contraction at high doses, indicating ischemia.

  • Assessment of valvular heart disease:

This diagnostics method evaluates the hemodynamic and functional consequences of valvular stenosis or regurgitation under stress conditions, as well as the effects of medical or surgical interventions. It can also detect the presence of ischemic mitral regurgitation, which is caused by the distortion of the mitral valve apparatus due to ischemic ventricular remodeling.

  • Assessment of cardiomyopathies:

Stress echocardiography can diagnose and monitor the progression of various types of cardiomyopathies, such as hypertrophic cardiomyopathy, dilated cardiomyopathy, restrictive cardiomyopathy, and arrhythmogenic right ventricular cardiomyopathy. It can also assess the response to medical or surgical treatments, such as beta-blockers, septal ablation, or myectomy.

  • Assessment of congenital heart disease:

Stress echocardiography allows for the comprehensive evaluation of the physiological and functional effects caused by congenital heart defects. This technique enables healthcare professionals to assess the impact of various types of defects, including atrial septal defect, ventricular septal defect, patent ductus arteriosus, coarctation of the aorta, and tetralogy of Fallot.

Furthermore, stress echocardiography plays a crucial role in assessing the effectiveness and potential complications of both surgical and percutaneous interventions. This includes evaluating the success of closure devices, stents, or valves that have been implanted to address these congenital heart defects.

Uding this method, healthcare professionals can determine the adequacy of these interventions and identify any potential issues that may have arisen, ensuring that patients receive the most appropriate and effective treatment. In summary, stress echocardiography serves as a comprehensive and versatile tool in the evaluation and management of congenital heart defects. Its ability to assess the hemodynamic and functional impact of these defects, as well as the effectiveness of interventions, makes it an invaluable asset in providing optimal care for patients with congenital heart conditions.

Protocols of stress echocardiography

Stress echocardiography requires a standardized protocol that includes the following steps:

  • Patient preparation:

The patient should be informed about the purpose, procedure, risks, and benefits of the test, and should provide informed consent. The patient should also be instructed to fast for at least 4 hours before the test, and to avoid caffeine, nicotine, and certain medications that may interfere with the test results, such as beta-blockers, calcium channel blockers, nitrates, or anti-ischemic drugs.

The patient should wear comfortable clothing and shoes, and should remove any jewelry or metal objects that may interfere with the ultrasound imaging.

  • Baseline evaluation:

The patient’s medical history, symptoms, medications, and risk factors should be reviewed. The patient’s vital signs, electrocardiogram (ECG), and oxygen saturation should be measured and recorded.

The patient’s resting echocardiogram should be performed, using a standard imaging protocol that includes at least two-dimensional, M-mode, and Doppler measurements of the left and right ventricular size, function, and hemodynamics, as well as the assessment of the valves, pericardium, and great vessels. The images should be stored digitally for later comparison with the stress images.

  • Stress protocol:

The patient undergos the chosen stress protocol, either exercise, pharmacological, or pacing, under continuous monitoring of the vital signs, ECG, and oxygen saturation. The stress protocol should be terminated when the target heart rate is achieved, or when the patient develops symptoms or signs of ischemia, such as chest pain, dyspnea, hypotension, arrhythmias, or ST-segment changes.

The stress echocardiogram should be performed either during the stress (on-treadmill or on-bike approach) or immediately after the stress (post-treadmill or post-bike approach), using the same imaging protocol as the resting echocardiogram. The images should be stored digitally for later comparison with the resting images.

  • Recovery phase:

The patient should be monitored until the vital signs, ECG, and oxygen saturation return to baseline levels, or until any symptoms or signs of ischemia resolve. The patient should be advised to report any adverse events or complications that may occur after the test, such as chest pain, palpitations, dizziness, or syncope. The patient should be discharged with appropriate instructions and follow-up recommendations.

Interpretation of Stress Echocardiography

Stress echocardiography is interpreted by comparing the resting and stress images, and identifying any changes in the regional wall motion and thickness of the left ventricle. The left ventricle is divided into 16 or 17 segments, according to the American Society of Echocardiography guidelines, and each segment is assigned a score based on its systolic function, using a 5-point scale:

  • 1 = normal,
  • 2 = hypokinetic,
  • 3 = akinetic,
  • 4 = dyskinetic,
  • 5 = aneurysmal.

The segmental scores are then summed to obtain a global score, called the wall motion score index (WMSI), which is calculated by dividing the total score by the number of segments.

A normal WMSI is 1, and a higher WMSI indicates worse global function.

The interpretation of stress echocardiography is based on the following criteria:

  • Normal response: There is no change or an improvement in the regional wall motion and thickness of the left ventricle during or after stress, and the WMSI remains unchanged or decreases.
    This means there’s no serious heart disease or lack of blood flow to the heart muscle.
  • Ischemic response: During or after stress, the left ventricle might start showing some problems with its wall motion and thickness. This could mean that there’s a significant issue with the coronary arteries or myocardial ischemia. We can determine where and how bad the ischemic segments are by looking at the distribution of the coronary arteries and the level of wall motion impairment.
  • Viable response: There is an improvement or a biphasic response of the regional wall motion and thickness of the left ventricle during or after stress, and the WMSI decreases or remains unchanged. This can be assessed by using low-dose dobutamine stress echocardiography, which can induce a biphasic response of the dysfunctional segments: an improvement of contraction at low doses, indicating viability, and a worsening of contraction at high doses, indicating ischemia.