Right atrium and superior vena cava flow velocity in man measured with the Doppler-Catheter Flowmeter-Telemetry system

Abstract

The flow velocity pattern in the superior vena cava and right atrium is described in sixty-six patients using the catheter tip Doppler ultrasonic flowmeter. The flow velocities were recorded simultaneously with superior vena cava or right atrium pressures, aortic or left ventricular pressure and electrocardiogram at rest and during cardiac arrhythmias. The normal flow velocity pattern in these areas is characterized by (1) a small “A” wave, which most likely represents small retrograde flow due to atrial contraction; (2) a large “S” wave during ventricular systole which appears to represent, forward flow at the time of atrial relaxation; and (3) a small “D” wave during ventricular diastole representing acceleration of blood through the superior vena cava and right atrium. Tricuspid insufficiency results in a large diastolic “D” wave and a diminished “S” wave, this being of possible diagnostic significance in this condition. A Valsalva maneuver results in an immediate decrease in flow velocity during the maneuver. In patients with atrial septal defect, secundum type, a bifid “A” wave is recorded, probably representing shunt through the septal defect. This technic appears to be useful in studying instantaneous, phasic superior vena cava and right atrial flow velocity in conscious, unanesthetized man in health and disease.