Jugular venous 'a' wave in dilated cardiomyopathy: sign of abbreviated right ventricular filling time

Dilated cardiomyopathy is a disease of the heart muscle involving an enlarged left ventricle (the heart chamber which pumps oxygenated blood to the body), with consequent loss of efficiency in pumping action. The pressure in the jugular vein, which returns blood from the brain to the heart, reflects the volume and pressure of the venous blood in the right side of the heart. It is often high in these patients, which is usually taken to mean congestive heart failure, a failure of the heart to keep up with the demands of the body. However, this may not always be the case. A dominant 'a' wave showing up on an electrocardiogram more likely identifies a problem with right ventricular filling with blood returning from the jugular vein. Twenty-three patients with dilated cardiomyopathy were examined. Eleven had a dominant 'a' wave and 12 had a dominant 'v' wave. Patients with the dominant 'a' wave had a higher heart rate and a different filling time. Possible mechanisms for the 'a' wave pattern are discussed. The most likely explanation is that the pattern reflects the direct effect of the limited time available for blood to flow in. When this condition is misdiagnosed as congestive heart failure, it is usually treated with diuretics to reduce blood volume. This would be ineffective if the problem is one of filling time, which responds to lowering the heart rate or reducing the duration of tricuspid regurgitation (backflow of the blood through a defective valve), both of which would increase the filling time. Heart failure is an imprecise diagnosis, and this noninvasive method of refining the diagnosis leads to more effective treatment. (Consumer Summary produced by Reliance Medical Information, Inc.)