Physiological Valvular Regurgitation

availability of a new tool it is incumbent on clinical investigators to develop guidelines for defining the normal range of findings. Many recent studies have suggested that with improving sensitivity of Doppler ultrasound devices, valvular regurgitation may be detected through the tricuspid valves of as many as 95% of the healthy subjects in some series,3 92% of pulmonary valves,4 and a variable and lower percentage of left-sided heart valves. In the early 1970s with M-mode echocardiography and later with two-dimensional echocardiography, similar confusion existed in framing strict and definitive criteria for the echocardiographic detection of mitral valve prolapse and its delineation from the spectrum of normal valve motion. Based on differing criteria for prolapse, a variety of references reported varying incidences of these findings in healthy subjects.56 Many of these studies are still open to question, and the true incidence of prolapse is still poorly defined although echocardiographic criteria continue to be modified and clinical criteria continue to be applied.7 It is clear, however, that a population of iatrogenically created "abnormal subjects" were mislabeled as having mitral prolapse. There is still confusion in dealing with issues concerning the natural history of mitral prolapse and the importance and medical and legal aspects of the need for subacute bacterial endocarditis prophylaxis. As pointed out in the study in this issue by Yoshida and colleagues8 from Kobe General Hospital, when over 200 healthy Japanese subjects were examined by color Doppler flow mapping echocardiography (subjects who were screened by physicians to verify the absence of murmurs as well as normal electrocardiograms), mitral regurgitation could be detected in up to 45% of individuals, tricuspid regurgitation in up to 70%, and pulmonic regurgitation in up to 88%. Aortic regurgitation was not encountered, however. These results confirm and expand previous studies, only a few of which specifically stressed the color flow mapping methodology.34,9-11 The frequency with which valvular insufficiency could be detected by Doppler echocardiography, as Yoshida and his coworkers8 point out, varied with age. The frequency of mitral regurgitation was increased in older subjects, which could potentially be a function of valve degeneration. However, the incidence of detectable valve regurgitation also varied in other surprising ways. Thus, regurgitant flow signals from the pulmonary and tricuspid valves