Cardiac stress test

This stress response can be induced through physical exercise (usually a treadmill) or intravenous pharmacological stimulation of heart rate.

Pulse rate, blood pressure and symptoms such as chest discomfort or fatigue are simultaneously monitored by attending clinical staff.

Abnormalities in blood pressure, heart rate, ECG or worsening physical symptoms could be indicative of coronary artery disease.

[2] Stress testing does not accurately diagnose all cases of coronary artery disease, and can often indicate that it exists in people who do not have the condition.

[3] A "normal" stress test does not offer any substantial reassurance that a future unstable coronary plaque will not rupture and block an artery, inducing a heart attack.

After a suitable waiting period to ensure proper distribution of the radiotracer, scans are acquired with a gamma camera to capture images of the blood flow.

By showing the relative amounts of radioisotope within the heart muscle, the nuclear stress tests more accurately identify regional areas of reduced blood flow.

This method, initially introduced by Diamond and Forrester in the 1970s, provides an estimate of the patient's post-test likelihood of disease.

This difference in response leads to a steal of flow and perfusion defects appear in cardiac nuclear scans or as ST-segment changes.

[36] The choice of pharmacologic stress agents used in the test depends on factors such as potential drug interactions with other treatments and concomitant diseases.

Pharmacologic agents such as adenosine, regadenoson (Lexiscan), or dipyridamole is generally used when a patient cannot achieve adequate work level with treadmill exercise, or has poorly controlled hypertension or left bundle branch block.

[37] Commonly used agents include: Regadenoson or dobutamine is often used in patients with severe reactive airway disease (asthma or COPD) as adenosine and dipyridamole can cause acute exacerbation of these conditions.

[39] Cardiac stress testing, used since the 1960s, has a history rooted in the diagnostic and prognostic assessment of patients with suspected coronary artery disease.

Cardiopulmonary exercise test using a treadmill .
Stress-ECG of a patient with coronary heart disease: ST-segment depression (arrow) at 100 watts of exercise. A: at rest, B: at 75 watts, C: at 100 watts, D: at 125 watts.