Explain the Steps in a Chemical Echo Stress Test

A chemical echo stress test is a diagnostic procedure ordered by a cardiologist to evaluate heart function and anatomy. Specifically, it is examines heart performance and coronary blood flow under conditions of both rest and stress, in order to elucidate a suspected cardiovascular abnormality and assess cardiac status. The process involves the use of ultrasound to visualize the heart’s chambers, valves, and muscular contractions, as well as to measure volume and direction of blood flow.

Pharmacological Stress Agent

• In chemical stress echocardiography, the pharmacological agent dobutamine is used to induce cardiovascular stress in lieu of physical exercise. Pharmacological stressors are reserved for individuals for whom exercise is contraindicated or physically impossible; otherwise, exercise is performed on a treadmill or a stationary bike. Dobutamine effectively duplicates effects of physical exertion on heart function.

Typical Procedure

• First, EKG electrodes are attached to the chest, an IV line is inserted, and a blood pressure cuff placed around the arm. Initial resting heart rate and blood pressure are measured at this time. While the individual being tested lies on his left side on an exam table, an echocardiography technician applies warmed gel to the chest, and places the transducer on top using slight pressure. The technician moves the transducer to several areas of the chest to obtain necessary images.

  To observe cardiac activity under stress, dobutamine infusion is started through the IV. The dosage is progressively increased until the target heart rate is achieved. During the process, EKG, blood pressure, and heart rate readings are monitored and multiple echo images are taken.

  Once the target heart rate is attained, dobutamine IV is ceased. Heart rate, blood pressure and EKG measurements, along with the sonogram imaging, continue until cardiac activity returns to relatively normal, or pre-stress, level. At this point, the test is finished and all the equipment is disconnected.

  The entire echocardiography procedure can require up to 1 to 1½ hours to complete. The recorded results are forwarded to a cardiologist for assessment and also made available to your physician. The gathered information will help determine the prognosis and establish the most effective course of treatment or prevention.

Considerations

• Medical facilities, like Rush Heart Institute of Meridian, Mississippi, recommend abstinence from food and drink for four hours prior to the testing procedure. Specific preparatory instructions are normally provided by a physician in advance.

  Although the risk is exceptionally small, stress induced cardiac arrest is a possibility. However, individuals undergoing the procedure are closely supervised by medical professionals who can intervene at the first sign of an abnormal reaction.