Congestive Heart Failure
DescriptionAn in-depth report on the causes, diagnosis, treatment, and prevention of CHF.
Alternative NamesCardiomyopathy; Heart Failure
Physicians can often make a preliminary diagnosis of heart failure with only a medical history and careful physical examination. An English study suggests, in fact, that the condition may be under-diagnosed. The following signs along with a history of heart disease strongly suggest heart failure:
Confirming these findings definitely or determining the severity of the condition, however, is difficult. Further tests are usually needed.
Laboratory Tests for Associated Medical Conditions
Both blood and urine tests are used to check for malfunctions of the liver and kidneys and to detect signs of diabetes.
Blood tests can also be used to evaluate the following:
Urine tests can also be used to assess:
Exercise Stress Test
The exercise stress test measures heart rate, blood pressure, and oxygen consumption while a patient is performing physically, usually walking on a treadmill. It is an important diagnostic component in determining heart failure symptoms. Doctors also use exercise tests to gauge long-term outlook and the effects of particular treatments.
An electrocardiogram (ECG) cannot diagnose heart failure, but it is simple and painless to perform and can indicate underlying heart problems by detecting the following:
The major benefit of an ECG is help in determining patients who most likely do not need an echocardiogram, a more accurate (but more expensive) diagnostic test.
The best diagnostic test for congestive heart failure is echocardiography coupled with studies known as Doppler flow. Echocardiography is a noninvasive, entirely safe test that uses ultrasound to image the heart as it is beating. Cardiac ultrasounds provide the following information:
Physicians use information from the echocardiogram for calculating the ejection fraction (the percent of the blood pumped out during each heartbeat), which is important for determining the severity of heart failure.
Radionuclide Ventriculography. Radionuclide ventriculography is an imaging technique that employs the injection of a tiny amount of radioactive material (called a trace element). As this substance passes through the bloodstream it is picked up on x-rays. This is a very important imaging technique for heart failure patients. It is very sensitive in revealing heart enlargement or evidence of fluid accumulation around the heart and lungs. It is typically used in concert with angiography.
Contrast Enhanced Magnetic Resonance Imaging. Magnetic resonance imaging (MRI) scans that use contrast dies to improve resolution are proving helpful for identifying patients with irreversible heart damage. Damage appears as very bright areas on the scan.
Physicians may recommend angiography if they suspect that blockage of the arteries is contributing to heart failure. This procedure is invasive and involves the following:
Major complications of angiography are rare (about 0.1%) but can occur. They include stroke, heart attacks, and kidney damage. The more experienced the medical center in this procedure, the lower the risk.
Tests for Markers
Researchers are looking for biologic factors (called markers) that will confirm a diagnosis or suggest a better or worse prognosis. Many are under investigation. Examples are the following.
Tumor Necrosis Factor. Elevated levels of tumor necrosis factor (TNF) may be a very strong and accurate predictor of a poor outlook. This immune factor is known to be a potent agent in the inflammatory process.
Natriuretic Peptides. These compounds may be elevated in response to the heart failure disease process and may help doctors determine whether a particular treatment is working. Of special interest is one called B-type natriuretic peptide (BNP), which may be associated with greater heart rate variability and severity in heart failure patients.
Brain Metabolites. High levels of a compound called N-acetylaspartate, generated as a byproduct of chemical processes in the brain, may indicate a poor outlook.