Medical Care
Medical treatment depends on the clinical presentation, which is determined by the differences in physiology of each type of double outlet right ventricle (DORV).
In DORV with no pulmonary valve stenosis (PS), medical management to control congestive heart failure (CHF) and improve the patient's condition prior to surgery should be instituted. Management of CHF requires medications such as loop diuretics (eg, furosemide), potassium-sparing diuretics (eg, spironolactone), after-load reducing agents, and digitalis. In addition, observe subacute bacterial endocarditis prophylaxis.
Infants with a subpulmonary ventricular septal defect (VSD) with a small or restrictive patent foramen ovale or atrial septal defect may require balloon atrial septostomy or blade atrial septostomy to improve interatrial mixing of saturated and desaturated blood and to decompress the left atrium.
In neonates with DORV and PS with marked cyanosis and hypoxemia, initial medical management consists of administration of intravenous prostaglandin E1 (PGE1) to open the ductus. The dosage used is 0.5 to 0.1 mcg/kg/min. The fraction of inspired oxygen (FIO2) should not exceed 0.4 (40%) unless there is associated pulmonary parenchymal pathology. Because of fixed intracardiac right-to-left shunting, higher FIO2 does not raise the O2 saturation.
Maintain patency of the ductus arteriosus with prostaglandin E1 in newborns with markedly diminished pulmonary blood flow (PBF) from severe pulmonary valve stenosis (PS). In newborns with double outlet right ventricle (DORV) and transposition of the great arteries who have subpulmonic ventricular septal defect (VSD), performing balloon atrial septostomy to enhance mixing of systemic and pulmonary circulations until surgery can be performed may be necessary.
Surgical Care
The two surgical approaches to double outlet right ventricle (DORV) are palliative and corrective.
Because surgery in these patients often is technically demanding, strongly consider referring these patients to a center with a large pediatric cardiac surgical program.
Palliative surgery
Similar to medical management, palliative therapy helps improve the patient's clinical condition, allowing him or her to gain weight and achieve optimal conditions for definitive surgical repair.
Infants with no PS who have a subpulmonary VSD, subaortic VSD, or doubly committed VSD and who present with CHF may undergo pulmonary artery (PA) banding to normalize pulmonary blood flow (PBF) and PA pressures.
Patients with subaortic or subpulmonary VSD with PS are cyanotic and have decreased PBF; therefore, they should undergo a systemic-to-PA shunt, usually a modified Blalock-Taussig anastomosis, to increase PBF. Alternatively, balloon pulmonary valvuloplasty may be performed, provided there is significant pulmonary valvar stenois and there are multiple obstructions in pulmonary outflow tract. [16, 17]
Definitive surgery
The relationship of VSD to the great arteries and the distribution of coronary artery (CA) determine surgical strategies.
Biventricular repair can be achieved in most patients with DORV. If biventricular repair is not feasible (eg, in straddling or abnormal distribution of chordae tendineae of atrioventricular [AV] valves and/or severe underdevelopment of left ventricle [LV]), a Fontan-type operation is an option with redirection of systemic (deoxygenated) blood into the PA without traversing a ventricle.
If biventricular repair is feasible, the 2 basic surgical steps to follow according to certain authors are (1) creation of an intracardiac tunnel to connect the LV to usually the aorta or, less commonly, the main pulmonary artery, where the conal septum is resected and any abnormal AV valve insertion on such conal septum are preserved; and (2) creation of an intracardiac or an extracardiac reconstruction to connect the RV to the main pulmonary artery. [18]
Several surgical approaches are appropriate in subpulmonary VSD; surgery is usually completed by age 3-4 months to avoid development of increased pulmonary vascular resistance. The surgical approach with a mortality rate of approximately 10-15% is the arterial switch operation with creation of an interventricular tunnel directing LV outflow into the PA, which becomes a neo-aorta (AO). [19]
If the VSD is subaortic or doubly committed, the optimal approach is to create a tunnel between the VSD and the AO to direct oxygenated blood into systemic circulation and also to eliminate mixing of the 2 circulations. Timing for this surgery depends on the size and clinical condition of the patient, but it is generally completed by age 4-6 months.
Heart transplantation
If the anatomy of associated lesions is too complex to consider an anatomic repair or if a repair results in unsatisfactory hemodynamics and intractable symptoms, consider heart transplantation. According to a report from the Children's Hospital of Pittsburgh, 15.4% of patients undergoing transplant were born with some form of DORV. [20] These patients require lifelong immunosuppression and close follow-up care.
Consultations
As with any other form of congenital heart disease (CHD), parents of patients born with DORV and transposition of the great arteries may meet with a geneticist to discuss the possibility of subsequent children having this or other forms of CHD. When CHD is detected, a detailed investigation for extracardiac malformation should be performed and vice versa. Also, issues such as preterm birth and stillbirth should be taken into account in risk assessment and risk stratification in patients born with CHD.
CHD belongs to the spectrum of birth defects and, despite technological advances, it significantly contributes to infant mortality. Because extracardiac anomalies occur in 15-45% of patients with CHD, these should always be investigated.
According to one study, the most prevalent extracardiac anomalies in general are the craniofacial malformations. However, the most prevalent associated with conotruncal heart defects are anomalies of the GI and genitourinary systems. Specifically, DORV may be associated with omphalocele, gastroschisis, facial clefting, and CHARGE (coloboma, heart disease, atresia choanae, retarded growth and retarded development and/or CNS anomalies, genital hypoplasia, and ear anomalies and/or deafness) syndrome.
Preterm infants have been shown to have more than twice as many cardiovascular malformations as do term infants, and 16% of all infants with cardiovascular malformations are preterm.
Prevalence of CHD is high among late stillbirths. In particular, a greater incidence of coarctation of the AO, double-inlet left ventricle, hypoplastic left heart, truncus arteriosus, DORV, and AV septal defect is noted among stillbirths.
Activity
Patients with DORV and transposition of the great arteries have no specific activity restrictions; their physiology may limit their exercise tolerance. After surgical intervention, some restrictions may be required depending on the hemodynamic result; however, these patients can usually participate in all age-appropriate activities.
Lifelong antibiotic prophylaxis is necessary prior to any potentially contaminated procedure, especially dental work.
Long-Term Monitoring
Provide follow-up care every 6-12 months for the first few years after surgery to detect complications of surgery that may include arrhythmias (eg, persistent atrial tachycardias, complex ventricular ectopy) and stenosis or partial obstruction, or both, of the interventricular tunnel.
Because arrhythmias result in morbidity, mortality, or both, patients may require long-term antiarrhythmic medication or may be candidates for radiofrequency ablation of an arrhythmogenic focus or circuit.
Interventricular tunnel obstructions may occur without clinical manifestations. In patients with severe left ventricular outflow obstruction, patients with tunnel obstruction may present with left ventricular failure. As many as 20% of patients who have undergone surgery for DORV require reoperation.
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Double outlet right ventricle (DORV) with transposition of the great arteries accounts for 26% of cases of DORV. The aorta (AO) is anterior and to the right of the pulmonary artery (PA), and both arteries arise from the right ventricle (RV). The only outflow from the left ventricle (LV) is a ventricular septal defect (VSD), which diverts blood toward the RV. Pulmonary veins drain into the left atrium (LA) after blood has been oxygenated in the lungs (L). Systemic venous return is to the right atrium (RA).
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This is an angiogram obtained during catheterization of a patient with double outlet right ventricle (DORV) with transposition of the great arteries. Injection of contrast though the catheter (arrow) into the left ventricle (LV) shows that blood is directed toward the right ventricle (RV) through a remote or doubly committed ventricular septal defect (VSD). The aorta (AO) is anterior to the pulmonary artery (PA) and both clearly arise from the RV.
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This is an angiogram obtained during catheterization of a patient with double outlet right ventricle (DORV) with transposition of the great arteries (see Media file 2). Blood fills the aorta (AO) and pulmonary artery (PA) almost simultaneously, which is another indicator of a remote or doubly committed ventricular septal defect (VSD) (curved arrow). LV indicates the left ventricle, RV indicates the right ventricle, and the small arrow to the left indicates the catheter.
