Learn about the most important cardiac screening test for those being evaluated for heart disease.
One common question that I am asked by those concerned about the risk for heart disease is “What heart function tests should be included in a good prevention and diagnostic cardiac screening?” From all the opinions available in the massive cardiologist’s tool box to assess basic function, this is what I recommend:
- Electrocardiogram (EKG)
- Exercise echocardiogram or nuclear stress test
- 24-hour Holter monitoring
EKG / Electrocardiogram:
An electrocardiogram or EKG should be done on everyone on their first visit to a cardiologist. An EKG establishes baseline information about the structure of your heart, its electrical conduction patterns and possibly arrhythmia. The 12-Lead EKG measures the electrical potential of your heart from 12 different directions. A resting EKG gives us information about the heart’s conduction system including current baseline heart rate, rhythm and possible heart blocks.
Voltage measurements signal strength indicate relative chamber size. An EKG also shows things like heart position and signals of possible ischemia (poor oxygen delivery). A record of your EKG when you are healthy is a good baseline for comparison, but resting EKG’s have limitations. We can miss problems that might be more evident when your heart is beating faster; hence, the need for further testing when the heart rate is elevated during an exercise test.
An echocardiogram is a noninvasive ultrasound of the heart that records specific geographic areas of the bleeding heart revealing blood-flow pattern and allows us to measure size and wall thickness of the heart chambers. We can get a good sense of where valves are. They may be leaking. They may be too calcified, or tight, or restrictive. In addition, an echo can detect possible enlargement of the heart as well as potential presence of fluid around the heart, as well as blood clots in the heart.
Your echocardiogram results are displayed on a video for a cardiologist to interpret. I use an echocardiogram in the office to get a dynamic picture of how the heart is functioning as a pump; how it is squeezing. It also provides information on ejection fraction, the percentage of blood that is moving out of your heart with each heartbeat, the overall indicator of heart health.
With a stress echocardiogram, the images are taken at rest and then compared to images taken immediately after exercise. In short, this test combines the diagnostic benefits of real-time ultrasound imaging and the exercise stress test. Blood-flow to specific regions of the heart muscle can be inferred for how well the heart wall is moving in that area. I have been doing stress echocardiograms since the mid 1980s.
Exercise Nuclear Stress Test:
This type of stress test is ordered to assess how your heart is functioning when heart rate and blood pressure are increased during the work of physical exertion. This gives us more information than a resting EKG. If the coronary arteries are blocked, then giving the heart a little work to do may reveal potential problems. The patient is walking on a treadmill hooked up to an EKG or he is on a bicycle. When you have a nuclear stress test, an intravenous catheter is inserted and nuclear material like Cardiolite is injected when the heart is at peak exercise. After a few minutes of recovery time laying on the table, imaging is performed for up to 30 minutes. Medications may also be administered in the IV that will increase the heart rate in place of exercise for those who cannot exert themselves physically. A positive finding indicates that blood-flow is restricted in one or more of the various regions of the heart.
A Holter monitor usually worn for 24-hours and includes every heartbeat for that period. Electrodes were placed on the chest and the recorder is worn in a saddle strap or belt. I order this test when patients have palpitations and to identify cardiac arrhythmias, or to monitor how well their medications are working. The heartbeats are analyzed from a sophisticated computer. Your heart is not a machine that beats at a fixed rate, as you know. It varies from a moment to moment with activity, emotion, and so on. Even psychological distress can cause changes in your heart rate.