Doppler echocardiography. The localization of cardiac murmurs.

SUMMARY A range-gated pulsed Doppler flowmeter has recently been developed that measures the average velocity of blood flow within a small tear-drop shaped (4 mm by 2 mm) sample volume. Unlike the continuous wave Doppler, the distance from the transducer face to the sampling site can be continuously varied by a range adjustment knob. Twenty patients with cardiac murmurs were evaluated in a noninvasive laboratory by brief cardiac physical examination, abbreviated phonocardiogram, complete echocardiogram, and localization of the murmurs by Doppler echocardiography. The localization depends on the detection of turbulent flow or jets at the sampling site. The murmurs included the diastolic rumble of mitral stenosis, mitral regurgitation, the murmur of left ventricular outflow tract obstruction, aortic stenosis, aortic insuffi-ciency, diastolic rumble of tricuspid stenosis, augmented right ventricular filling sound in atrial septal defects, pulmonic stenosis, pulmonic insufficiency, and high velocity flow through the obstruction in ccarctation of the aorta. Mitral stenosis Mitral regurgitation Pulmonic stenosis Pulmonic insufficiency Aortic insufficiency Atrial septal defects Coarctation of aorta Tricuspid stenosis Phonocardiography Aortic stenosis FOR NEARLY 20 years intracardiac phonocar-diography has been used to localize heart sounds and murmurs within the heart and great vessels.' Recently a range-gated pulsed Doppler flowme-ter was developed which measures the average velocity of flow within a small 4 mm by 2 mm sample volume at any point along the ultrasonic beam.2 The output of the device is an audio signal, whose frequency is proportional to the velocity spectrum contained within the sample volume. Since most murmurs are generated by turbulent flow, this device can be used to localize jets or other areas of turbulent flow which have a characteristic wide frequency band sound. This paper describes 810 the application of the pulsed Doppler flowmeter to the localization of a wide variety of cardiac murmurs. Method Most of the 20 patients in the study (Table 1) were admitted for cardiac evaluation, but a few were referred from the outpatient clinics for localization of interesting murmurs. Only 4 of the 20 did not undergo cardiac catheterization. Prior to catheterization and angiography, the patients were brought to the laboratory, where a thorough cardiac physical examination was performed. Graphical tracing, including ECG, external carotid pulse, and one channel phonocardiogram were recorded. A complete echocardiographic examination was usually performed. The final step was the noninvasive localization of the cardiac murmurs, using the range-gated pulsed Doppler flowmeter. The technique for murmur localization is …