Systolic clicks: A clinical, phonocardiographic, and hemodynamic evaluation

Abstract

This study was comprised of 809 phonocardiographic tracings on a total of 598 patients, of whom 135 revealed early systolic clicks, and 11 more showed mid or late systolic clicks. Detailed clinical and phonocardiographic characteristics of the systolic clicks were noted, and the more significant early systolic clicks differentiated from the comparatively benign ones occurring just before mid-systole, in mid-systole, and in late systole. Clicks of the latter type were encountered mostly in normal hearts, but they were also found in abnormal states. The early systolic clicks were noted to occur in anomalies involving congenital malformations of the stenotic type in the aortic and pulmonary valves, and in those involving dilatation of the aorta and pulmonary artery. The aortic clicks generally tended to be of maximal intensity at the apex and varied little during respiratory cycles. The pulmonic clicks were maximal at the second left intercostal space parasternally and were loudest during expiration, sometimes disappearing completely with inspiration. The incidence of early systolic clicks was appreciably high in congenital aortic stenosis, while they were present in about half the cases of congenital isolated pulmonary stenosis. The latter anomaly in a majority of the cases was of the mild to moderate type. In these conditions the early systolic clicks always preceded the ejection murmurs. In congenital aortic stenosis the aortic closure was unusually loud in most instances; in congenital pulmonary stenosis a few cases revealed an abnormally loud pulmonic closure. Of the anomalies involving the aorta the early systolic clicks were found to be quite consistently present in cases of truncus communis, but were also noted in extreme cases of tetralogy of Fallot and only occasionally in coarctation of the aorta, transposition of the great vessels, tricuspid atresia, aortic regurgitation, and atherosclerosis of the aorta. Dilatation of the pulmonary artery associated with Eisenmenger's physiology, Taussig-Bing complex, and idiopathic dilation of the pulmonary artery revealed that early systolic clicks were a relatively constant finding in these conditions. Pulmonary hypertension at less than systemic levels and pulmonary dilatation secondary to large left-to-right shunt with normotensive pressures were sometimes noted to be associated with early systolic clicks. With respect to timing the ejection component of the first heart sound, as well as the aortic clicks, the concept of isometric rise of aortic pressure as reflected in simultaneous indirect arterial tracings is discussed. The early systolic clicks were considered to be a pathologic manifestation of the second major, or ejection, component of the first heart sound and, depending on their origin, to reflect the isometric contraction period or beginning of the ejection phase of either ventricle. In congenital aortic stenosis and valvular pulmonary stenosis the early systolic clicks seemed to originate at the valvular level, occurring after the atrioventricular valve closure at a mean time interval of 0.055 and 0.033 second, respectively. In other conditions the vessel wall of the aorta or the pulmonary artery appeared to be their seat of origin. The mode of occurrence of the more benign mid and late systolic clicks could not be ascertained. The presence of early systolic clicks was considered an abnormal finding in itself, and their proper evaluation was regarded as being of significant diagnostic importance. Their absence did not imply exclusion of any given entity or hemodynamic state.