Course of tricuspid atresia in the Fontan era.

Tricuspid atresia is an uncommon form of congenital heart disease and long-term survival was rare before the Fontan era. It was thought that the long-term survival of patients with tricuspid atresia would be improved by the introduction of the Fontan procedure and its subsequent modifications. This study reviews the clinical course of 84 patients with tricuspid atresia identified in the first year of life in the Fontan era. Prior palliative operations, their results and their ultimate application for the Fontan procedure were considered. Eleven patients died before surgical intervention and 5 did not undergo catheterization or echocardiographic confirmation before death. Five children underwent the Fontan procedure without prior palliation and 1 child does not require palliation at the present time. Sixty-seven patients (80%) had surgical procedures before evaluation for the suitability of a Fontan operation. Thirty-four patients had a second surgical palliation and 9 patients had a third palliation. The surgical mortalities for the first, second and third palliative surgery were 17.9, 17.6 and 0%, respectively. Thirty-two patients (38%) underwent the Fontan procedure and 2 deaths occurred (6%). An estimate of the probability of surviving for 1 year was 64% (95% confidence limits 54 to 74%) and that of 8 years was 55% (95% confidence limits 44 to 66%).

Telemetric detection of cardiac allograft rejection. Correlation of electrophysiological, histological, and biochemical changes during unmodified rejection.

Intra-abdominal mismatched heterotopic cardiac allograft transplantation without immunosuppression was performed in eight pigs. Postoperatively, daily electrophysiological studies were carried out either with exteriorized temporary epicardial pacing wires (n = 4) or by a telemetrically controlled implanted pacemaker connected to permanent epicardial pacing leads (n = 4). Electrophysiological studies data were correlated with histopathologic and biochemical findings from daily myocardial biopsies. Electrophysiological studies revealed no significant alteration of sinus or atrioventricular node function, refractoriness, or ventricular pacing threshold. However, ventricular voltage amplitude, measured through the electrodes, decreased steadily with time in all donor hearts and was significantly correlated with histopathologic rejection grade (p less than 0.001) and with adenosine 5'-triphosphate (ATP) depletion (p less than 0.001). Ventricular voltage amplitude less than 75% of baseline occurred 4.5 +/- 1.5 days after transplantation, and this decreased voltage amplitude coincided with a moderate to severe (Grade 2 or 3) histological rejection pattern with a sensitivity of 89% (17 of 19) and a specificity of 77% (17 of 22). Similar changes in voltage amplitude were not found in control hearts. Myocardial tissue ATP values fell significantly from control values with early (Grade 1) rejection (p less than 0.05). Evidence for oxygen free radical injury was indicated by a rise in conjugated dienes of free fatty acids; this increase in diene level occurred 4.3 +/- 1.2 days postoperatively and then regressed during the terminal stages.(ABSTRACT TRUNCATED AT 250 WORDS)

Noninvasive transcutaneous cardiac pacing in children.

Noninvasive transcutaneous cardiac pacing is an emergency pacing modality with proven benefits for adult patients. During induction of anesthesia for heart surgery, we externally paced 22 children (aged 0.9-17.9 years and weighing 6.96 to 51 kg) using a commercially available device to pace approximately 10 beats per minute faster than the spontaneous heart rate. Three pacing electrode sizes were used (the standard adult size and two specially manufactured smaller sizes). A total of 56 pacing trials were conducted, 53 of which were successful in obtaining capture. A mean output of 63 +/- 14 mA (range, 42-98) at threshold using the large electrodes was comparable to published adult requirements. Lower current outputs were needed with the medium (53 +/- 12 mA; range, 36-92) and small electrodes (51 +/- 11 mA; range, 29-82). In any given patient, the large electrodes required more current (p less than 0.01) to obtain capture, but delivered less current density (p less than 0.01) and exhibited less impedance (p less than 0.01) than the smaller electrodes. The mean threshold energy requirement was 0.12 +/- 0.01 joules/beat regardless of pad size. Output, current density, impedance and energy requirements did not vary with age, weight or chest size. No complications of external pacing were noted. We conclude that noninvasive transcutaneous pacing can be used safely and effectively in children, and that chest size might necessitate the use of smaller electrodes in children weighing less than 15 kilograms.