Diastolic Myocardial Vibrations Caused by Poststenotic Coronary Flow Instabilities

It has been previously reported in the literature that high-frequency diastolic heart murmurs in the myocardium occur in patients with coronary artery stenoses. It has also long been hypothesized that these murmurs are caused by flow instabilities downstream of the stenosis; the most obvious mechanism for this phenomenon is that pressure fluctuations due to the flow transition excite vibrations in the coronary artery wall which then radiate into the myocardium. A prior pilot study [1], utilizing Doppler vibrometry, an ultrasound based technique, was able to measure high frequency (100–1000Hz) but low amplitude (1–10μm) left ventricular wall vibrations in patients with coronary artery stenosis. Furthermore, the intensity of the wall vibrations was shown to significantly correlate with the percent stenosis (as determined by quantitative coronary angiography). This evidence suggests that ultrasound doppler vibrometry offers the possibility to detect coronary artery stenosis with a low-cost, relatively cheap, and non-invasive modality [2]. This particular study, therefore, seeks to quantify the relationship between the poststenotic flow instabilities and wall vibrations in order to optimize the vibrometry measurements.