Dynamic Fontan Operation With Skeletal Muscle Conduit For Single Ventricle With Pulmonary Hypertension

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Purpose : The purpose of this experimental study is to test the feasibility of a new surgical procedure "dynamic Fontan operation" with skeletal muscle ventricle (SMV) or linear skeletal muscle conduit constructed by the electrically paced skeletal muscle grafts for single ventricle (SV) with pulmonary hypertension (PH) to obtain a possible proxy for high risk patients for Fontan procedure. Methods : As the preliminary studies using 33 dogs, SMVs constructed with latissimus dorsi were stimulated in a mock-circulation system to test (1) the effects of electrical preconditioning on contractile properties and fatigue resistance and (2) mechanical function of intrathoracic SMV.These studies showed that (1) electrical preconditioning produced highly fatigue resistance from muscle fiber transformation and metabolic shift to aerobic metabolism, and (2) an intrathoracic SMV with a resting volume of 2ml/kg showed sufficient mechanical property as maximum SWI of 0.7±0.06gm/ml to replace total ri … More ght ventricular work. Base on these pilot studies, skeletal muscle ventricles (SMV) (n-5) and skeletal muscle conduit (n=8) constructed by a pedicled left lattissimuss dorsi (LD) flap in 13 puppies, was electrically precondtioned for 6 weeks within the left thorax. The surgical model of the single ventricle with pulmonary hypertension was made by obliteration of the right ventricular cavity with concomittent closure of the tricuspid valve and the right pulmonary artery by using a cardiopulmonary bypass (CPB). Dynamic Fontan was established by (1) an aortic homograft anastomosed between the right atrium and pulmonary artery incorporated with intra-thoracic SMV or (2) the linear contractile conduit anastomosed between the right atrium and pulmonary trunk. After the termination of CPB, skeletal muscle grafts were stimulated with a trained-pulse (25 Hz). Results : Profound right heart failure was noted without skeletal muscle graft stimulation at the presence of increased pulmonary vascular resistance (11±3.2 Wood units, 412±34% of pre CPB values), whereas conduit stimulation showed significant augmentation of the mean pulmonary flow by 68±23% and the systolic aortic pressure by 33±5% at a physiological range of CVP (13.2±0.7mmHg). Right heart function curve analysis confirmed dramatical augmentaion of right heart performance by dynamic Fontan, restoring almost normal pulmonary circulation even with pulmonary hypertension.Conclusion : Dynamic Fontan procedure may be a viable surgical option for the single ventricle with pulmonary hypertension, which can not be a Fontan candidate. Less