Real-time inferior vena caval ultrasonography: normal and abnormal findings and its use in assessing right-heart function.

We studied the inferior vena cava (IVC) as an index of right-heart function in 111 patients. A two-dimensional echocardiographic sector was used to visualize the IVC, and its M-mode cursor was used to generate a time-motion record of the IVC size and pulsation. Normal subjects had a small presystolic A wave (less than 125% of the end-diastolic IVC dimension), a small systolic V wave (less than 140% of the end-diastolic IVC dimension), and a 50% inspiratory decrease in IVC dimension. The A wave was absent in patients with atrial fibrillation. When normalized for body surface area, mean end-diastolic IVC dimension correlated with mean right atrial pressure (r = 0.72, p less than 0.001). An A wave greater than or equal to 125% of end-diastolic IVC dimension was recorded in 71% of patients with sinus rhythm and an elevated right ventricular end-diastolic pressure of 10 mm Hg or greater, but in no patient with right ventricular end-diastolic pressure of less than 10 mm Hg (p less than 0.001). A V wave greater than or equal to 140% of end-diastolic IVC dimension was recorded in 75% of patients with severe tricuspid insufficiency, but in no patient with mild or no tricuspid insufficiency (p less than 0.001). The inspiratory decrease in IVC dimension correlated with radionuclide right ventricular ejection fraction (r = 0.75, p less than 0.001); no respiratory variation in end-diastolic IVC dimension occurred in patients with significant right ventricular dysfunction (right ventricular ejection less than 25%) or in patients with constrictive pericarditis.