Right atrial pressure-volume relationships in tricuspid regurgitation.

Abstract

Pressure-volume relationships in the right atrium were examined before and after the creation of acute exerimental tricuspid regurgitation in pigs. A 1.3 kHz multielectrode impedance catheter with a measuring current of 4 mA was used to determine instantaneous right atrial pressure and relative blood volume; right atrial dimension was assessed simultaneously with ultrasonic crystals attached to the atrial walls. Impedance volume waveforms and ultrasonic crystal dimensions closely paralleled each other at baseline and after the induction of tricuspid regurgitation. The normal right atrial pressure-volume plot exhibited a figure-of-eight configuration, with an "a-loop" and a "v-loop" corresponding to the a-wave and v-wave of the right atrial pressure tracing. With severe tricuspid regurgitation, atrial pump function was abolished, and the pressure-volume plot exhibited a single clockwise loop, consistent with complete ventricularization of the right atrium. Intermediate degrees of tricuspid regurgitation preserved the figure-of-eight loop, but the size of both the a-loop and the v-loop were increased, consistent with a Starling-type load imposed on the atrium by the regurgitant blood volume. Increased right ventricular afterload mediated by constriction of the pulmonary artery and infusion of methoxamine reversibly converted the right atrial pressure-volume loop from that of mild to that of severe tricuspid regurgitation. Alternatively, constriction of the inferior vena cava and infusion of nitroprusside changed the right atrial pressure-volume loop from that of a severe pattern of tricuspid regurgitation to a less severe type of pattern. Infusion of dobutamine increased the size of the a-loop relative to the v-loop both at baseline and after induction of tricuspid regurgitation. We conclude that tricuspid regurgitation induces changes in right atrial mechanics that can be detected and quantified with an impedance catheter. Circulation 73, No. 4, 799-808, 1986. TRICUSPID

Differential impact of short periods of rapid atrial pacing on left and right atrial mechanical function

“…Last, atrial conductance volumes were not corrected for parallel conductance by means of resistance due to surrounding tissue (31). However, the analytic methods employed in this study were not dependent on absolute volumes and were consistent with previous studies involving the RA (4,8,21,23) and LA (27,36).…”

“…To ensure volume sampling accurately reflects changes in atrial (vs. caval or pulmonary vein) volume, each volume segment was individually assessed for its synchronization and phase relationship to the other segments. Conductance catheters have previously been used to quantify RA and LV volume (4,8,21,23,27,36). Relative RA conductance-derived volume changes have previously been shown to correlate highly to relative volume changes calculated with caval flow analysis (r ϭ 0.97, r 2 ϭ 0.94, P Ͻ 0.001) (21).…”

Right atrial function in hypertensive patients: effects of antihypertensive therapy

“…8 The RV and RA function has been assessed in experimental and clinical conditions. [7][8][9][10] Noninvasive RA function has been performed with echocardiography by means of RA volume measurements. [11][12][13] Indirectly, RA function can also be evaluated with the use of pulsed Doppler echocardiography by means of trans-tricuspid flow velocity measurements in a similar manner with that used for the estimation of left atrial function.…”

Reservoir and conduit function of right atrium: impact on right ventricular filling and cardiac output

“…The three components of atrial function are 1) reservoir function, storing blood when the tricuspid valve is closed and releasing stored blood when it opens; 2) conduit function, passive blood transfer directly from the coronary and systemic veins to the right ventricle when the tricuspid valve is open; and 3) booster pump function, atrial contraction in late diastole to complete ventricular filling (10,13,31). Previous studies have demonstrated that pathologically altered left atrial conduit-to-reservoir function is an important determinant of left heart function and can profoundly affect cardiac performance (2, 4, 14 -17, 30, 33, 34, 38), but studies examining right atrial (RA) reservoir and conduit function are limited.The mechanics of the right atrium are complex (5,8,24,26). In 1628, William Harvey was the first to identify the atrium as a "receptacle and store-house" and reported that the right atrium was "the first to live, and the last to die" (12).…”

“…The mechanics of the right atrium are complex (5,8,24,26). In 1628, William Harvey was the first to identify the atrium as a "receptacle and store-house" and reported that the right atrium was "the first to live, and the last to die" (12).…”