Use of Ultrasound to Measure Left Ventricular Stroke Volume

Several empirical observations made during ultrasound examinations for pericardial effusion have led to the possibility that this diagnostic technique might be used to measure left ventricular stroke volume in man. The hypothesis that left ventricular stroke volume was proportional to the amplitude of an echo originating from a portion of the left ventricle near the mitral ring (MREa) times the distance between the echoes from the anterior and posterior ventricular walls (LVD) has been validated. Ultrasound examinations were performed simultaneously with cardiac output determinations using the direct Fick method on 16 patients proven to have competent mitral and aortic valves. Correlation between the two methods of measuring left ventricular stroke volume was excellent (r = 0.973; P < 0.001). When ultrasound measurements were used in the regression equation to predict stroke volume, the calculated values were within 11 ml or 15% of those determined by the Fick method. The fact that an ultrasound examination is simple, can be done as a bedside determination in a matter of minutes, and is totally harmless to the patient make it a promising diagnostic procedure. The measurement of left ventricular stroke volume represents another addition to the growing list of medical uses for this intriguing technique.