I have been enrolled in the Graduate Education in Medical Sciencesprogram for the past year. This Spring, I am doing a Translational Medicine Preceptorship with Dr. Maulik Majmudar. I just finished my first week, and it has already been an amazing experience. I spent two days this week watching Nuclear Imaging Stress Tests and then two more days in the Cardiac Catheterization Lab, both at MGH. I’ve learned a ton already, and wanted to write up a few interesting things I learned about stress testing.
Stress testing is conducted for three main reasons: screening, diagnosis, and prognosis. High risk individuals receive stress testing for screening, those with chest pain receive stress testing for diagnosis, and those with known/existing heart conditions receive stress testing for prognosis. Stress testing can be either physiological or pharmacologic. A physical stress test usually involves walking on a treadmill or riding a stationary bicycle. Pharmacologic stress tests require an injection of a vasodilator to increase the load on the heart.
Electrocardiogram (ECG/EKG) recordings and blood pressure measurements are made and monitored throughout the course of the rest and stress intervals. There can be a number of different “readouts” that are done to quantify the impact of stress on the heart. The common ones used at MGH include the echocardiogram, which is ultrasound based, and nuclear imaging, which is involves the injection of radioactive isotopes. Other imaging modalities, such as CT, PET, and MRI, are also used.
The personnel running the stress tests look for significant changed in the ECG and BP during the stress test, as well as significant changes in blood flow to the heart, along with the heart’s ability to contract properly, to determine how well the heart performs under stress. If the results of the stress test indicate ischemia (heart muscle death), the patient may be referred to the cardiac catheterization lab, where physicians can take a closer look at the arteries of the heart for blockages that may have caused the tissue death.