The pulmonary valve in direct phonocardiography.

LIE pulmonary second sound plays an important role in the clinical diagnosis of congenital and acquired heart diseases. Since phonocardiographic recordings from the chest wall present the pulmonary valve sound as part of a composite of sounds produced by 2 valves of the heart, it was our interest to demonstrate the pulmonary sound by direct phonocardiography. Cardiac sounds and murmurs heard and recorded at the chest wall under normal and pathologic conditions are composed of audible vibrations associated with different mechanical events of the cardiac cycle occurring at the same time or in close sequence. Therefore, separation and identification of vibrations due to a single event, such as closure of 1 valve, is frequently difficult. The problems increase with anatomic variations, as they occur in congenital malformations of the heart and great vessels and with a combination of such defects. It is reasonable to assume, that recording directly from the surface of the heart, as close as possible to the presumed origin of the single sound will increase the understanding of those vibrations as well as their variation with pathologic conditions. Direct phonocardiography has been used in the past under experimental conditions. Most investigators have recorded vibrations only from the ventricles. To our knowledge, Wiggers and Dean,1 were the first to have recorded sounds from the aorta and pulmonary artery as well. Bertrand and associates2 recently reported an experimental study in dogs employing a stethoscopic bell pick up held in