The bicaval anastomosis technique for orthotopic heart transplantation yields better atrial function than the standard technique: an echocardiographic automatic boundary detection study.

BACKGROUND

Atrial function is an important determinant of cardiac performance. In patients who undergo operation by standard heart transplantation atrial enlargement, distortion of geometry and asynchronous contraction resulting from the donor/recipient atrial connections may affect atrial function. The bicaval anastomosis technique should be free from these limitations.

METHODS

We used the echocardiographic automatic boundary detection technique to obtain on-line time/volume curves of right and left atria from patients who had undergone bicaval (n = 22) or standard (n = 27) heart transplantation and from 15 control subjects. Maximal, middiastolic, preatrial contraction, and minimal volumes of both atria were measured. Reservoir volume (defined as the difference between maximal and middiastolic atrial volumes); pump volume (defined as the difference between preatrial contraction and minimal atrial volumes); and conduit volume (defined as the difference between left ventricular stroke volume and the sum of reservoir and pump volumes) were derived for both atria. Atrial emptying fraction was calculated as the difference between maximal and minimal volumes divided by the maximal volume and expressed in percent and pump fraction as the pump volume divided by the sum of reservoir and pump volumes. Tricuspid and mitral regurgitation, evaluated by color-flow Doppler scanning, were considered significant when they were greater than grade 1. Atrial ejection force was calculated from mitral and tricuspid flow velocities at atrial contraction.

RESULTS

In patients who had bicaval heart transplantation, both atria were smaller than in patients who underwent standard heart transplantation. With the bicaval technique right and left atrial emptying (right 45% +/- 9% vs 36% +/- 10%, p < .05; left 51% +/- 8% vs 39% +/- 8%, p < .001) and pump fractions (right 57% +/- 17% vs 19% +/- 13%, p < .001; left 45% +/- 28% vs 22% +/- 12%, p < .01) were greater than with the standard technique and similar to those in control subjects. Right atrial ejection force was significantly greater in bicaval (10.0 +/- 5.6 kdyne) than in standard heart transplantation (4.5 +/- 2.2 kdyne, p < .0001). Significant tricuspid or mitral regurgitation was rarely found in bicaval heart transplant recipients (3 and 1 of the 22 patients, respectively), although they were much more frequent after standard heart transplantation (13 and 8 of the 27 patients, respectively).

CONCLUSIONS

Heart transplantation performed with the bicaval anastomosis technique determines smaller atrial volumes, yields better right and left atrial function and fewer atrioventricular valve regurgitation than the standard technique.