R. K. H. Wyse

Early and late arrhythmias after the Fontan operation: predisposing factors and clinical consequences.

OBJECTIVE--To study the incidence, predisposing factors, and clinical significance of arrhythmias early and late after the Fontan operation for congenital heart disease. PATIENTS AND METHODS--All 104 consecutive patients undergoing Fontan repair from 1975 to 1988 were studied retrospectively. Hospital records were reviewed for perioperative arrhythmia. Clinical information and annual electrocardiograms were available for all 78 hospital survivors during a follow up of up to 13 years (mean 3.7 years). Ambulatory electrocardiographic monitoring was performed in 67 patients (81%). RESULTS--Eleven patients (10.6%) developed a perioperative tachycardia (eight, atrial flutter; three, His bundle tachycardia). Multivariate analysis showed that raised preoperative mean pulmonary artery pressure and low aortic saturation were significant risk factors for the development of atrial flutter (r2 = 0.32, p = 0.0001) but not for His bundle tachycardia. Despite intensive medical treatment 10 of these 11 patients died. At the last visit 72 (92%) of the 78 patients were in sinus rhythm on their standard 12 lead electrocardiogram. Junctional rhythm was present in three patients, two patients had atrial flutter, and one had a paced rhythm. Ambulatory monitoring did not show important bradycardia or ventricular arrhythmias. Actuarial survival free of supraventricular arrhythmia was 82% at eight years after operation. Multivariate analysis identified older age, increased right atrial size, and raised mean preoperative pulmonary artery pressure as risk factors for arrhythmia during intermediate follow-up (r2 = 0.46, p less than 0.001). Late tachycardias, in contrast to those occurring in the perioperative period, were not associated with an increased mortality. CONCLUSIONS--Except for his bundle tachycardia in the perioperative period, early and late arrhythmias after a Fontan operation seem to be a consequence of adverse preoperative and postoperative haemodynamic function. The perioperative outcome is therefore poor even when the patient can be restored to sinus rhythm. Medical and surgical modifications to improve the haemodynamic disturbances associated with arrhythmias are therefore indicated.

Correction of coarctation of the aorta in neonates and young infants: an individualized surgical approach

Because of the controversy concerning the ideal surgical repair for symptomatic coarctation of the aorta presenting in neonates and infants, our entire series of 179 children under the age of 12 months undergoing repair between January 1, 1976 and December 31, 1984 was reviewed. Of this group, 109 were neonates, 43 infants aged 31-90 days and 27 infants aged 90 days-12 months. Twenty patients had a simple coarctation and 159 had complex coarctation with additional intracardiac anomalies such as ventricular septal defect (37 patients also had pulmonary artery banding). One hundred and twenty-four were repaired with a subclavian flap operation, 32 with resection and end-to-end anastomosis and 23 with complex repairs (e.g. patch and reversed flap). Type of repair was the surgeons choice and was selected on the basis of the anatomy of the coarctation. Total perioperative mortality was 15% (N = 27) while late mortality was 12% (N = 21). Twenty-one risk factors for mortality were evaluated by logistic analysis and the method of Cox. There was no risk difference between end-to-end versus subclavian flap repairs and all but one death occurred in patients with complex coarctations. Risk for in hospital death was increased by only one variable: the need for repair in the neonatal period. Risk for death in the first year of life was increased by the presence of congestive heart failure at initial presentation while later death correlated with intracardiac surgery. Recoarctation occurred in 28 patients (18.4%), all but 4 of these occurred in patients undergoing neonatal repairs.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term results of homograft valves in extracardiac conduits.

Between 1971 and 1986, 335 patients received various extracardiac valved conduits between one of the heart chambers and the pulmonary arteries. The group of patients who received aortic homograft conduits and survived the operation were analysed in detail. The age varied between 9 days and 18 years (mean 7.1 +/- 0.7 years), weight 2.4 kg-63.5 kg (mean 17.8 +/- 10.8 kg). The diameter of the conduit used was 10-30 mm (mean 20.8 mm). Multivariate analysis revealed a highly significant model (P less than 0.005) which showed that the time interval between harvesting and use of the homograft (P less than 0.02) and the earlier date of operation (P less than 0.05) were the major risk factors for obstruction. Homografts used within 3 weeks of harvesting had freedom from obstruction of 79% at 8 years; homografts used between 3-6 weeks had freedom from obstruction of only 55% at 8 years. Homografts used alone performed significantly better than those extended with woven Dacron tubes. At 10 years, 93% of homografts used alone were free of obstruction compared to 52% of homografts extended with a Dacron tube. We conclude that aortic homografts used within 3 weeks of harvesting provide a reasonably durable conduit for a period of 12 years. Longer storage, and extension of the homograft with a woven Dacron tube should be avoided.

Hemodynamics, Regional Myocardial Blood Flow, and Sarcoplasmic Reticulum Calcium Uptake in Right Ventricular Hypertrophy and Failure

Either right ventricular hypertrophy (RVH) or failure (RVF) was produced by pulmonary arterial banding in 47 piglets aged 3-6 weeks. When sufficient time was allowed to elapse after banding, RVH was present in 30 and had progressed to RVF in 17. These two groups were compared with 24 control, i.e., normal pigs (C). Animals with RVF differed from RVH and C animals by having reduced cardiac output and clinical signs of failure. Both RVH and RVF had significantly elevated right ventricular peak systolic pressures (RVS), weights (GMRV), and RV/LV systolic pressure ratios (these variables all increased greater than 100% compared with C). The RV (dP/dt)max correlated with RVS in C (r = 0.687, P less than 0.001), but this relationship was absent in RVH with higher RVS and GMRV. The RV (dP/dt)max correlated closely with RV blood flow/g per min in C (r = 0.638, P less than 0.01) and in RVH (r = 0.462, P less than 0.02). Calcium uptake by RV sarcoplasmic reticulum (SR) was diminished in RVH compared to C and further diminished in RVF (38%, P less than 0.001). Calcium uptake by LV SR also fell in RVF, suggesting that SR calcium uptake is merely a passive reflection of myocardial function. Our results also suggest that hemodynamic and subcellular changes seen in RVF may be detected during the compensated stage of RVH.

Allografts in the Rastelli procedure: Techniques

Children with transposition of the great arteries (TGA) (VA discordance), ventricular septal defect (VSD) and anatomical left ventricular outflow tract obstruction (LVOTO) used to be treated by the Mustard operation, closure of the VSD and surgical relief of the obstruction. This carried out a mortality in excess of 50% (1, 2), largely due to the difficulty in relieving the LVOTO. The prognosis of children with this complex of disorders was improved by the application of the Rastelli operation (3). This operation consists in enlargement of the VSD, diversion of the LV outflow to the aorta by an intraventricular tunnel/patch and connection of right ventricle (RV) to pulmonary artery (PA) by an external valved conduit (Figs. 1–3). Details of the operative technique we use have been published elsewhere (4, 5).

Utilizaçäo de valvas homólogas e heterólogas em condutos extracardíacos

O conceito do uso de um conduto extracardiaco para estabelecer uma via de saida, conectando o ventriculo direito com o tronco pulmonar, ou seus ramos, foi desenvolvido na decada de 60. Entre 1971 e 1986, 335 pacientes receberam, no The Hospital for Sick Children, de Londres, condutos extracardiacos para o lado direito do coracao; 176 destes foram homoenxertos aorticos, preservados em solucao antibioticonutriente; 140 heteroenxertos (Hancock, Ross, Carpentier-Edwards, lonescu-Shiley e 19 tubos nao valvulados. Estes condutos foram usados na correcao de defeitos cardiacos complexos. A idade media foi de 6,34 anos e o peso medio, de 17,8 kg. O diâmetro interno dos condutos variou de 8 a 30 mm. A mortalidade hospitalar foi de 29,2% e o seguimento dos sobrevivente teve uma duracao maxima de 14,3 anos, sendo que apenas 40% delas foram relacionadas ao conduto extracardiaco. A curva atuarial, livre de obstrucao, dos condutos extracardiacos foi significativa, quando se analisaram os homoenxertos, face a cada grupo de heteroenxertos (p < 0,005). Os fatores de risco mais importantes foram: o numero de complicacoes pos-operatorias, para obitos tardios; a severidade das lesoes associadas, para as reoperacoes; a data da cirurgia, para a troca do conduto extracardiaco, e a severidade das lesoes associadas, para a obstrucao. Assim, conclui-se que, a longo prazo, o uso de condutos valvulados extracardiacos tem bons resultados, especialmente no que se refere aos homoenxertos. Pelos dados apresentados, os homoenxertos aorticos, preservados em solucao antibiotico-nutriente, continuam a ser nossa primeira escolha na reconstrucao da via de saida ventriculo-pulmonar.

CARDIOVASCULAR EFFECTS OF NEUROMUSCULAR BLOCKADE DURING INDUCED HYPOTHERMIA

1. Young lambs were used to study the effects of progressive cooling and rewarming on cardiovascular function during neuromuscular blockade induced by gallamine.