The first step in treating any medical condition involves making a diagnosis. In cardiology, we have many tests which help us diagnose coronary disease, valve disease, heart failure, and electrical problems of the heart. Some tests are invasive and require placement of catheters and other such devices in the heart. Much more frequently, however, we use non-invasive tests to diagnose various cardiac disorders. Some of the more commonly employed non-invasive tests will be described here.
Echocardiograms are ultrasound tests performed to take pictures of the valves within the heart and the strength of the heart. They are often simply called "echoes."
There are four valves within the heart. These valves keep the flow of blood within the heart moving in the right direction. Many people with heart murmurs have valves that either fail to open normally or fail to close normally. Using an echocardiogram, one can actually see the valves and the blood flow though the valve. It is very common to find minor valve leakages on an echo, but the real value of the test is the ability to find valve problems that have the potential to cause serious problems in the future.
Echocardiograms are also frequently used to measure the strength of a person's heart. People with shortness of breath, fluid retention, or unusual fatigue may have problems with weakness of heart function. With an echo, the heart's ability to pump blood can be very accurately estimated. The echo is very helpful in establishing or disproving a diagnosis of heart failure. Echocardiograms are also useful for finding heart abnormalities that could put a person at risk for stroke or heart rhythm abnormalities.
The most common serious medical condition in the United States is coronary artery disease. The coronary arteries sit on top of the heart and supply blood and oxygen to the heart itself. Blockages of the coronary arteries frequently lead to heart attack.
The most commonly used non-invasive test used to diagnose coronary disease is the stress test. A stress test involves a walk on a treadmill. As the patient walks, the heart's demand for oxygen increases. If the heart is not getting enough oxygen because of blocked arteries, the patient' EKG may change in very specific ways. This abnormal EKG response to stress helps the doctor diagnose coronary blockages.
Nuclear Cardiac Scan
For people unable to walk on a treadmill, there are various intravenous drugs that can be used to mimic stress. These chemical stress tests, sometimes called adenosine or dobutamine tests, almost always involve the use of radioactive imaging or echo imaging of the heart.
Many patients have symptoms that suggest either an abnormally slow or abnormally fast heart rate. If a simple resting EKG does not provide the diagnosis, the doctor may request a Holter Monitor. This monitor is worn by a person for 24 or 48 hours, recording every heart beat that the person has over the monitored period. This test is sometimes called an ambulatory EKG, and it is expected that a person would continue with all of their routine daily activities while wearing the monitor.
For people who experience infrequent symptoms that do not occur on a daily basis, the doctor may request a 4 week Event Monitor. This device is very similar to the Holter monitor. The Event Monitor, however, needs to be triggered by the patient when a symptom is felt. Both the Holter and Event Monitors are very helpful in identifying heart rhythm abnormalities.
