Use of the Ultrasonic Doppler Method for Timing of Valvular Movement

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Abstract
The ultrasonic Doppler method was employed to time the rapid movements (opening and closure) of the mitral and aortic valves. To exclude signals due to slowly moving structures (heart walls), the Doppler tracing was processed by a filter that eliminated low frequencies. Clear tracings containing two deflections, one due to the opening and the other to the closure of each valve, were obtained. The valvular origin of the deflections was verified by recordings simultaneous with intratardiac pressures in five dogs. The ultrasonic Doppler tracing was found to be a satisfactory aid in the differentiation of various extra heart sounds in 24 patients. Thus, the second heart sound precedes, the third heart sound follows, and the opening snap is simultaneous with the signal due to mitral opening. The fourth heart sound is simultaneous with the atrial component of the unfiltered Doppler signal. Ejection clicks and systolic clicks are simultaneous with or follow the signal due to aortic opening. Because of its simplicity and safety, this method used in conjunction with the phonocardiogram should prove helpful in distinguishing the opening snap, third and fourth heart sounds, and certain additional auscultatory phenomena.