Tricuspid valve closure in pulmonary atresia and important RV-to-coronary artery connections

Pulmonary Atresia With an Intact Ventricular Septum: Preoperative Physiology, Imaging, and Management

Pulmonary atresia with intact ventricular septum (PA-IVS) is a rare complex cyanotic congenital heart disease with heterogeneous morphological variation. Prenatal diagnosis allows for developing a safe plan for delivery and postnatal management. While transthoracic echocardiography allows for detailed delineation of the cardiac anatomy, additional imaging modalities such as computed tomography, magnetic resonance imaging, and catheterization may be necessary to further outline features of the cardiac anatomy, specifically coronary artery anatomy. The size of the tricuspid valve and right ventricular cavity as well as the presence of right ventricle–dependent coronary circulation help to dichotomize between biventricular repair versus univentricular palliation or heart transplantation, as well as predicting the expected survival. The delineation and understanding of these features help to dictate both medical and surgical management.

Natural History of Pulmonary Atresia With Intact Ventricular Septum and Right-Ventricle–Dependent Coronary Circulation Managed by the Single-Ventricle Approach

BACKGROUND

Long-term outcome of patients with pulmonary valvar atresia and intact ventricular septum with right-ventricle-dependent coronary circulation (PA/IVS-RVDCC) managed by staged palliation directed toward Fontan circulation is unknown, but should serve as a basis for comparison with management protocols that include initial systemic-to-pulmonary artery shunting followed by listing for cardiac transplantation.

METHODS

Retrospective review of patients admitted to our institution with the diagnosis of PA/IVS-RVDCC from 1989 to 2004. All angiographic imaging studies, operative reports, and follow-up information were reviewed. Right-ventricle-dependent coronary circulation was defined as situations in which ventriculocoronary fistulae with proximal coronary stenosis or atresia were present, putting significant left ventricle myocardium at risk for ischemia with right ventricle decompression.

RESULTS

Thirty-two patients were identified with PA/IVS-RVDCC. All underwent initial palliation with modified Blalock-Taussig shunt (BTS). Median tricuspid valve z-score was -3.62 (-2.42 to -5.15), and all had moderate (n = 13) or severe (n = 19) right ventricular hypoplasia. Median follow-up was 5.1 years (9 months to 14.8 years). Overall mortality was 18.8% (6 of 32), with all deaths occurring within 3 months of BTS. Aortocoronary atresia was associated with 100% mortality (3 of 3). Of the survivors (n = 26), 19 have undergone Fontan operation whereas 7, having undergone bidirectional Glenn shunt, currently await Fontan. Actuarial survival by the Kaplan-Meier method for all patients was 81.3% at 5, 10, and 15 years, whereas mean survival was 12.1 years (95% confidence interval: 10.04 to 14.05). No late mortality occurred among those surviving beyond 3 months of age.

CONCLUSIONS

In patients with PA/IVS-RVDCC, early mortality appears related to coronary ischemia at the time of BTS. Single-ventricle palliation yields excellent long-term survival and should be the preferred management strategy for these patients. Those with aortocoronary atresia have a particularly poor prognosis and should undergo cardiac transplantation.

Temporary decompression of the right ventricle to assess the right ventricle-dependent coronary circulation in pulmonary atresia with intact ventricular septum

We repaired a case of pulmonary atresia with intact ventricular septum in which the blood supply to the left anterior descending coronary artery depended on the right ventricle. At the time of a bidirectional Glenn operation, total cardiopulmonary bypass with venous drainage from the right atrium was performed in order to evaluate the safety of right ventricular decompression required for a planned Fontan operation. We confirmed the dependence of the coronary perfusion on the right ventricle by demonstrating transient depression of the ST segment in the epicardial electrocardiogram during temporary decompression of the right ventricle. To prevent ischemic myocardial damage, we then performed an extracardiac Fontan operation with a temporary venous shunt and without cardiopulmonary bypass.

Pulmonary Atresia with Intact Ventricular Septum

The prognosis for patients with pulmonary atresia with intact ventricular septum is poor with and without conventional surgical treatment. Because of this reason, a comprehensive program of medical, transcatheter, and surgical treatment is necessary to improve the long-term outlook of these infants. Algorithms of management plans should be developed based on the presence of right ventricular-dependent coronary circulation as well as size and morphology of the right ventricle. In a tripartite or bipartite right ventricle, transcatheter radiofrequency perforation is preferable. Alternatively, surgical valvotomy may be performed. Augmentation of pulmonary blood flow by prolonged infusion of prostaglandin E(1), stenting the ductus, or a surgical modified Blalock-Taussig shunt may be necessary in some of these patients. In patients with a unipartite or very small right ventricle or a right ventricular-dependent coronary circulation (Tricuspid valve Z score < -2.5), augmentation of pulmonary flow along with atrial septostomy should be undertaken. Follow-up studies to determine the feasibility of biventricular repair should be undertaken and, if feasible, surgical or transcatheter methods may be used to achieve the goals. If not suitable for biventricular repair, one-ventricle (Fontan) or one and one-half ventricular repair should be considered. Comprehensive and well-planned treatment algorithms may help improve survival rate.

Veno-venous bypass to prevent myocardial ischemia during right heart bypass operation in PA, IVS, and RV dependent coronary circulation

There is a risk of myocardial ischemia in patients with pulmonary atresia and intact ventricular septum associated with right ventricle dependent coronary circulation, especially during open heart operation. Cardiopulmonary bypass unloads the right ventricle, and thereby reduces the coronary perfusion pressure in an area that is wholly or partly dependent on the right ventricle. We present a veno-venous bypass technique to keep the right ventricle beating and ejecting to supply the oxygenated blood into the right ventricle dependent myocardium and consequently to prevent myocardial ischemia during right heart bypass operation.

Cyanotic congenital heart disease with decreased pulmonary blood flow in children

Of the "five T's" of cyanotic congenital heart disease--tetralogy of Fallot, TGA, TAPVC, truncus, and tricuspid valve abnormalities (tricuspid atresia, stenosis, and displacement)--the first and last are commonly associated with diminished PBF. The four features that comprise tetralogy of Fallot--right ventricular hypertrophy, VSD, overriding aorta, and subpulmonary stenosis--are all secondary to a single morphogenetic defect: failure of expansion of the subpulmonary conus. This also explains the variability in clinical presentation. When neonates need intervention, shunts are usually performed. Coronary arterial anatomy must be defined before repair, which is usually done after these infants are 3 months of age. Although children with repaired tetralogy of Fallot are not completely "normal," markedly increased longevity and improvement in quality of life can be achieved. When major associated defects are present, such as atrioventricular canal defect, diminutive pulmonary arteries or collateral vessels, or left heart lesions, the prognosis changes from excellent to merely good. Tetralogy of Fallot with absent pulmonary valve syndrome is physiologically different from other tetralogy of Fallot conditions and characterized primarily by airway obstruction from massive dilatation of the central and perihilar pulmonary arteries; repair with pulmonary artery reduction is necessary. Tricuspid valve abnormalities include atresia, hypoplasia (i.e., pulmonary atresia with intact ventricular septum), and displacement (i.e., Ebstein anomaly). The pathophysiology that dictates these children's clinical condition (and prognosis) relates to three factors: (1) status of the tricuspid valve, (2) presence and size of a VSD, and (3) TGA or normally related great arteries. Virtually all children with tricuspid valve abnormalities can be palliated; reparative options include repair using two-ventricle, one-ventricle, or 1-1/2 ventricle repair. Children with critical pulmonary stenosis generally have a normal tricuspid valve and right ventricle. Balloon dilation is usually the only therapy necessary.

Evaluation and management of pulmonary atresia with intact ventricular septum

Pulmonary atresia with intact ventricular septum (PA/IVS) is a spectrum of diseases with varying severity of right ventricle hypoplasia and potential for biventricular, univentricular, or hybrid repairs. Pessimistic outcome measures for PA/IVS may give way to optimism with the refinement of early diagnosis and early intervention to encourage right ventricle flow and optimize growth. To this end, PA/IVS has become a focus of innovative interventions (e.g., fetal surgery) and new catheter-based and surgical techniques.

Pulmonary atresia with intact ventricular septum: results of the Fontan procedure

BACKGROUND

Children with pulmonary atresia and an intact ventricular septum show a heterogeneous spectrum of cardiac anomalies. A biventricular repair is attainable in some; a Fontan procedure or a one-and-a-half ventricle is the only possible repair for others. Children with right ventricle-to-coronary artery connections, with or without right ventricle-dependent coronary artery blood flow, are a high-risk group.

METHODS

Between May 1980 and December 1994, 22 children underwent a Fontan operation for the treatment of pulmonary atresia with an intact ventricular septum at The Hospital for Sick Children, Toronto. The mean age was 5.8 years (median, 4.9 years). All children had had at least one pre-Fontan palliative procedure; 19 had two, and 7 of these had three or more. Right ventricle-to-coronary artery connections were present in 15 children, including 5 with right ventricle-dependent coronary artery blood flow. Thromboexclusion of the right ventricle was done in 10 children, with 7 undergoing it before and 3 at the time of the Fontan procedure.

RESULTS

There were three early deaths (13.6%) and one late death. The actuarial survival at 10 years after the Fontan operation was 80%. Early postoperative complications occurred in 4 children. Follow-up was completed in all children at a mean of 4 years (range, 1 to 12.5 years) after the Fontan operation. Atrial arrhythmia occurred in 3 children, and permanent pacemakers were required in 4.

CONCLUSIONS

Results of the Fontan operation for the treatment of pulmonary atresia with an intact ventricular septum are satisfactory. Thromboexclusion of the right ventricle is indicated in the presence of right ventricle-to-coronary artery connections without right ventricle-dependent coronary artery blood flow. The right ventricle should not be decompressed or thromboexcluded in children with right ventricle-dependent coronary artery blood flow, and at the Fontan operation, saturated blood must enter the right ventricle.