TOTAL ATRIOVENTRICULAR CARDIAC TRANSPLANTATION PRESERVES ATRIAL SYSTOLE AND VENTRICULAR DIASTOLIC FILLING

Background Total orthotopic heart transplantation was recently introdu ced into clinical practice as an alternative technique for orthotopic cardiac transplantation. Total cardiac transplantation uses separate b icaval and left and right pulmonary anastomoses, whereas the standard technique of cardiac transplantation uses atrioplasty. Because the ana tomic differences between total and standard orthotopic heart transpla ntation occur at the atrial level, this study compares atrial systolic function and biventricular filling (dV/dt) between the standard and t otal transplantation techniques. Methods and Results Forty-eight mongr el canines (23 to 31 kg) were used for 12 total and 12 standard orthot opic cardiac transplantations. Right and left ventricular (RV/LV) func tion and AV synchrony were analyzed with micromanometry, sonomicrometr y, ultrasonic flow meters, and intraoperative echocardiography. Result s are expressed as mean+/-SEM (ANOVA, paired and unpaired t tests, and chi(2) test). There were no significant differences in baseline funct ion (pretransplantation), bypass times, and cardiac ischemic times bet ween the two groups. Posttransplantation plantation sinus rhythm was p reserved in all total (P<.0025) and in only one standard transplantati on recipient (all required atrial diastole pacing). Significant decrea ses in RV/LV dV/dt from 113+/-13 and 123+/-14 mL/s to 69+/-6 and 85+/- 10 mL/s after transplantation were measured in the standard group. No significant changes occurred in the total group after transplantation with respect to RV/LV diastolic filling. After transplantation, left a trial contractility and relaxation (-dP/dt) decreased significantly in the standard group by 43% and 70%, respectively, whereas in the total transplantation group, there were no observed changes in left atrial contractility and -dP/dt. A significant increase in the septum to RV f ree wall dimension in the standard group suggests altered geometry. Co nclusions Total AV transplantation is a feasible alternative to standa rd cardiac transplantation and conserves both normal sinus rhythm and synchronized beating of the atria and ventricles. Ischemic and bypass times are comparable in patients undergoing either method. These data suggest that RV/LV diastolic function and geometry and atrial systole are better pre served in the total AV transplantation technique.