THE ABC’S OF CARDIOVASCULAR TESTING
As part of your initial or ongoing evaluation, tests may be ordered to help your physician better evaluate certain aspects of your cardiovascular condition. This list, although not comprehensive, highlights some of the most common tests in the field of cardiovascular medicine.
1) Electrocardiogram (EKG) – This is a tracing of the electrical impulses generated by the heart. This simple test, performed by a nurse, requires the patient to lie still for approximately 30 seconds. It provides a wealth of information regarding the heart including the heart rhythm and rate, estimations of chamber size, evidence of acute or prior heart attacks, and drug/electrolyte effects on the heart.
2) Echocardiogram (Echo) – This is an ultra-sonographic evaluation of the heart. It is performed by a techni¬cian in the office and requires the patient to lie on their back or side for 20 minutes. It provides information regarding cardiac function (ejection fraction) and size as well as an accurate evaluation of narrowed or leaky heart valves.
3) Stress Test – Stress tests fall into three main categories, which will be discussed separately.
A) Treadmill Exercise Stress Test – This is a provocative test of cardiac function performed to evaluate how the heart performs at peak exercise. It involves walking on a treadmill under the supervision of a nurse and physician until a predetermined heart rate is achieved. This test provides information regard¬ing possible blocked arteries (coronary artery disease), exercise-induced rhythm changes, as well as the patients overall exercise capacity.
B) Nuclear/Echo Stress Testing – These tests are used in similar instances as a regular treadmill stress test; however, the combined imaging modalities can greatly improve the diagnostic accuracy for detecting blocked arteries. A nuclear stress test requires the patient to be injected with a tracer, which is taken up by the heart. Images are obtained at rest and again after stress. By comparing these sets of images, information regarding areas at risk for damage can be detected. A stress echocardio¬gram utilizes the same principals, but instead of a tracer, ultrasound images of cardiac function are obtained before and after stress.
C) Chemical Stress Test – If a patient cannot walk on a treadmill for whatever reason, drugs can be administered to mimic exercise conditions and allow us to obtain the same information in combination with ECHO or nuclear imaging.
4) Holter Monitors/Event Recorders/Loop Monitors- These tests are useful in the evaluation of cardiac rhythm disturbances. A Holter monitor is usually worn for 24 hours and allows an analysis of every heart beat during that period. If the heart falls out of rhythm, the nature and duration of the rhythm disturbance helps to guide therapy. If a Holter monitor result is normal, yet symptoms persist, an event or loop monitor is often useful. The patient keeps one of these monitors with them for several weeks, and if the patient experiences a symptom the monitor is held up to the heart to record the rhythm. Since many rhythm disturbances are sporadic, some patients may need to keep these monitors for one or two months before a diagnosis can be made.
5) Vascular Studies (Carotid, Lower Extremity Arterial and Venous Doppler Ultrasound) – This category encompasses the evaluation of blocked arteries in vascular beds other than the heart. The evaluation is similar in nature to that of an echocardiogram. Carotid ultrasound is used to detect disease in the arteries of the neck, which, if blocked, can lead to stroke. Arterial Doppler of the lower extremities is used to detect blockage in the legs, which can cause pain and cramping when walking. Lower extremity venous Doppler is used to detect blood clots in the venous circulation.
6) Angiograms – These tests are performed at the hospital to confirm the results of the non-invasive tests and to perform intervention if required. Two broad categories including heart catheterization and peripheral catheter¬ization will be discussed separately:
A) Heart Catheterization – This test is performed by your physician at the hospital. It involves placing a small tube in the leg and passing catheters to the arteries which supply blood to the heart. X-ray dye is then injected and movie type pictures are obtained of these arteries, allowing the physician to deter¬mine if blockages exist. Depending on the location and severity of the blockages, as well as other fac¬tors, treatment with medicine, angioplasty/stent, or bypass surgery is recommended.
B) Peripheral Catheterization – Similar to a heart catheterization, catheters can be used to take pictures of arteries supplying blood to the brain (carotids), kidneys, or legs with similar therapeutic decision¬ making.