The differentiation of organic and “innocent” systolic murmurs*

Summary The pattern of a systolic murmur is closely related to the hemodynamic alterations in the cardiovascular system. Close attention to the pattern (timing and shape) of a murmur is necessary for the proper understanding of a cardiac disorder from a functional point of view. Similarly the pattern of a systolic murmur is probably the single most useful feature available for distinguishing an organic from an "innocent" murmur. The more commonly used terms of description of murmurs, that is, according to intensity, location, quality and transmission are most useful when considered within the framework of murmur pattern. Whereas the ability to describe accurately a murmur according to its intensity, location, quality, and transmission is acquired with moderate ease, to learn to recognize the pattern of a murmur by auscultation requires more intense application on the part of the observer. Frequent correlation of auscultatory findings with the phonocardiogram improves one's ability to recognize the timing and shape of a murmur. With increasing ability reference to the phonocardiogram becomes less necessary. Two types of innocent systolic murmurs which occur frequently are the circumscribed (or late) systolic murmur believed to be of extracardiac origin and the ejection systolic murmur conveniently referred to as Still's murmur. Correct identification of the first and differentiation from the murmur of mitral regurgitation are possible by its nonholosystolic nature and sometimes by the association of systolic click(s) in the same or other areas of the precordium. Correct identification of Still's murmur and differentiation from the murmur of aortic stenosis is usually possible by its characteristic quality and its variability, as described earlier. Obviously a murmur is only one of the clinical signs available to the clinician and concentration on this one sign to the exclusion of the other available information is unrewarding and even misleading. Only with proper attention to the history, to all of the physical abnormalities (or the lack of same), and to the available laboratory investigations will an intelligent evaluation of a systolic murmur be forthcoming.