What is stress testing?
Echocardiography evaluates cardiac function:
- At rest
- During stress evoked by adrenergic (dobutamine) challenge or by dynamic exercise (treadmill)
- Immediately following dynamic exercise
Indications for Stress Testing
- Suspected or known coronary artery disease.
- Myocardial evaluation.
- Evaluation of dyspnea to identify possible cardiac origin.
- Mitral stenosis and regurgitation.
- Aortic stenosis.
- Hypertrophic cardiomyopathy.
- Pulmonary hypertension.
Those with tachyarrhythmias and hypertension should not have stress testing; abdominal aortic aneurysm is a relative contraindication.
Types of Stress Testing
Exercise stress testing is preferred to a pharmacologic challenge due to its predictive superiority for outcomes. Anyone who can tolerate exercise should have this type of stress testing. Use of a treadmill, the most common technique, involves pre-exercise imaging and image acquisition during exercise. Those who cannot perform exercise testing can pharmacologically challenge the myocardium with dobutamine stress, a potent ischemic stressor. A temporary pacemaker can be used for those who cannot exercise. The pacing rate is raised in combination with the pharmacologic dobutamine stress method.
Complementary Imaging Techniques
An important part of stress testing is imaging the heart before, during, and after the challenge. 2D echocardiography is used to make “before-and-after” side-by-side comparisons of both global and left ventricular systolic function. Images at rest, pre-peak, and at peak stress are compared.