Dobutamine stress echocardiography.

Dobutamine is a synthetic catecholamine with predominant beta-stimulation. Its half-life is approximately 2 min. The positive chronotropic and inotropic effects of dobutamine induce myocardial ischaemia if significant coronary artery obstruction is present. Regional ischaemia produces regional wall motion abnormalities which can be detected by echocardiography. Most dobutamine stress protocols start at an infusion rate of 5 micrograms.kg-1.min-1 and increase to a peak dose of 40 or 50 micrograms.kg-1.min-1; to further increase heart rate, a bolus injection of 0.25-1.0 mg atropine is added. Test endpoints are the detection of new wall motion abnormalities, the occurrence of severe complications or achievement of the target heart rate. Viable myocardial regions have a positive inotropic reserve, which can be stimulated by dobutamine and detected by echocardiography. Indications for the use of dobutamine stress echocardiography are to prove stress-inducible myocardial ischaemia and to detect myocardial viability. The test should only be performed for the detection of stress-induced myocardial ischaemia if patients are unable to undergo exercise echocardiography, or if patients fail to reach their required test level in exercise echocardiography.

Arbutamine stress echocardiography.

Arbutamine, a new potent non-selective beta-adrenoceptor agonist with mild alpha 1-sympathomimetic activity, has been developed specifically for pharmacological stress testing. The drug acts like physical exercise, increasing both heart rate and myocardial contractility. Sensitivity, specificity and accuracy in detecting significant stenotic coronary artery disease are 76%, 96%, and 82%, respectively, again similar to those of exercise echocardiography. The drug is delivered by a computerized drug delivery and monitoring device (GenESA) which adjusts the infusion rate according to the patient's heart rate data feedback. The drug is generally well tolerated and has an acceptable safety profile. This article describes recent clinical experience with arbutamine and presents preliminary results of a multicentre multinational study which evaluates the clinical utility and safety of the GenESA system in diagnosing coronary artery disease.

Stress echocardiography: personnel and technical equipment.

In recent years, stress echocardiography has gained broad acceptance as a non-invasive method for the diagnosis of coronary artery disease. Facing different protocols, dosages and instrumentation, official guidelines for the performance, standardization and quality control of stress echocardiograms are needed; however, so far they are not available. This paper recommends the type of personnel and technical equipment needed for stress echocardiography laboratories, based on experience gained during more than 2000 stress echocardiographic procedures. To perform stress echocardiography, a cardiologist and a technical assistant--both well trained over a large number of tests--should be involved. The laboratory must have basic equipment such as a 12-lead ECG, blood pressure monitoring capacity, a treadmill or bicycle for ergometry, a precision intravenous delivery system for pharmacological stress testing as well as an adequate echo table; additionally, emergency equipment is mandatory. The ultrasound machine should contain transducers with high 2-D resolution; most important is a digital image acquisition system which facilitates performance and interpretation through side-by-side display of synchronized rest and stress images. Finally, there is a need for proper patient preparation and the obtaining of informed consent.

Detection of myocardial viability using stress echocardiography.

Asynergic myocardial regions in patients with coronary artery disease can be viable. They may have the ability to improve their function after restoring coronary blood flow. Asynergic but viable myocardial regions have a positive inotropic reserve which can be stimulated by catecholamines. Because echocardiography is an established method for evaluating regional left ventricular function, it has the potential to detect the inotropic response of asynergic myocardial regions. In the clinical setting, prediction of left ventricular functional improvement after revascularization is particularly important. Dobutamine stress echocardiography is the most frequently used stress echocardiographic test for detection of myocardial viability. Dobutamine is infused at low rates of 2.5 to 20 micrograms.kg-1.min-1 to detect myocardial viability. This paper reports on the sensitivity and specificity of the method for the detection of viability and its usefulness for prediction of left ventricular functional improvement after revascularization.