Changes in Flow Velocity Pattern of the Superior Vena cava and the Area of Tricuspid Regurgitant Jet in Patients with Tricuspid Regurgitation during Lower Body Negative Pressure

Studies were made on 19 healthy subjects and 39 patients by combined Doppler and two-dimensional echocardiography to evaluate the effect of a lower body negative pressure (LBNP) on the flow velocity pattern of superior vena cava (SVC) and area of tricuspid regurgitant jet in patients with tricuspid regurgitation (TR). TR was defined according to color Doppler criteria as the presence of a pansystolic signal in the right atrium (RA), extending 1.0 cm2 or more beyond the tricuspid annular plane. Areas of RA and tricuspid regurgitant signal, SVC diameter, and peak velocities of systolic and diastolic waves were measured at an LBNP of 0 and then of-20 and -40 mm Hg. Significant decreases in the areas of RA and TR and in the diameter of the SVC were observed in all cases. During graded change in the LBNP, the peak velocity of the systolic wave of the SVC decreased in normal subjects and in patients with mild TR, but did not change in patients with moderate to severe TR. In normal subjects, the diastolic wave of the SVC did not change appreciably, but in all patients with TR it decreased significantly. In 3 patients with laminar TR, no changes were observed in the TR and RA areas or in the peak velocities of the systolic and diastolic waves of the SVC. These findings suggested that the blood flow velocity patterns of the SVC and TR areas are influenced by preload reduction and that changes in peak flow velocity of the SVC during graded change of the LBNP in TR patients differ from those of normal subjects.