Goals of tests to evaluate heart failure
Your doctor will probably use several tests to learn more about the structure and function of your heart. The goals of these tests are to:
- Confirm the diagnosis of heart failure.
- Determine the type of heart failure you have.
- Determine its cause.
- Assess the severity.
- Identify any complications you may have.
- Help predict the course of your heart failure.
These tests evaluate many aspects of your physical condition that your doctor is not able to measure by talking to you or doing a physical exam. The following section outlines the type of information your doctor can obtain about the structure and function of your heart from diagnostic tests.
Important features about the structure of your heart include the:
- Overall size of your heart. If you have systolic heart failure, you probably have a dilated, enlarged heart. In this case, the more your heart is enlarged, the worse your expected outcome (prognosis) is. Ongoing high blood pressure also can cause left ventricular hypertrophy, which can also result in an enlarged heart.
- Size of each chamber of the heart. Different causes of heart failure can be associated with enlargement of different chambers of the heart, and the pattern of enlargement therefore can provide important clues about the cause of heart failure. For example, mitral valve stenosis is usually associated with a very large left atrium, but a normal-sized left ventricle. In contrast, mitral valve regurgitation is associated with significant enlargement of both of these chambers.
- Shape of your heart. Types of systolic heart failure that affect all chambers of the heart equally will usually cause a dilated heart, thinning of all of the heart's walls, and poor pumping ability. Systolic heart failure from a large heart attack, on the other hand, will predominantly cause only one wall of the heart to function poorly. Diastolic heart failure from chronic high blood pressure (hypertension) often causes a moderately enlarged heart with very thick walls.
- Thickness and motion of the walls of your heart. Some causes of heart failure result in thinning and decreased motion of all the muscular walls of the heart; this is characteristic of dilated cardiomyopathy that is inherited or caused by mitral valve regurgitation or toxins such as alcohol. In contrast, heart failure caused by coronary artery disease is usually associated with thinning and decreased motion of the walls of the heart where heart attacks have occurred, but slightly thicker and more forcefully contracting walls in the other regions that are attempting to compensate for the damaged walls. Diastolic heart failure caused by chronic high blood pressure is characteristically associated with very thick walls of the heart that may be functioning more forcefully than in a normal heart.
- Left ventricular ejection fraction (LVEF). This measurement represents the fraction of blood that is in the left ventricle when it relaxes between beats that is successfully pumped out during contraction. The normal LVEF is more than 55%. In severe systolic heart failure, the LVEF can be as low as 10% to 20%. The LVEF is the single best predictor of survival in people with systolic heart failure.
- Function of the valves. An echocardiogram is the best test to evaluate the function of the heart valves. Leakage or blockage of the valves on the left side of the heart (the mitral and aortic valves) can cause left-sided heart failure, and abnormal function of the valves on the right side (the tricuspid or pulmonic valves) can cause right-sided heart failure.
- Degree of blockage of the coronary arteries. This information is crucial to rule out severe coronary artery disease as a cause of heart failure. In older people or in people with risk factors for coronary artery disease, it is often necessary to perform a stress test or coronary angiogram to make sure that the coronary arteries are not severely blocked.
- Effect of stress on the heart. The effect of different forms of stress such as exercise or medicines on the heart can provide information about the cause and severity of heart failure.
- Electrical activity of the heart. The identification of abnormal heart rhythms such as atrial fibrillation or ventricular tachycardia may suggest that one of these abnormal heart rhythms is the cause of heart failure. But more importantly, the identification of such an abnormal rhythm would suggest that the person is at risk for a serious complication of heart failure and may require more specialized treatment.
- Thickness of the pericardium and the presence of pericardial fluid. The pericardium is the thin sac that surrounds your heart. A thick, calcified pericardium suggests that heart failure is caused by constriction of the heart by a diseased pericardium. If the pericardium is filled with fluid (pericardial effusion), this may suggest an inflammatory or infectious cause of your heart failure.
| Author: | Robin Parks, MS | Last Updated: September 1, 2006 |
| Medical Review: | Caroline S. Rhoads, MD - Internal Medicine Stephen Fort, MD, MRCP, FRCPC - Interventional Cardiology | |
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