Double Outlet Right Ventricle, With Transposition

INTRODUCTION

Background: Double outlet right ventricle (DORV) is a type of ventriculoarterial connection in which both the aorta (AO) and pulmonary artery (PA) arise entirely or predominantly from the right ventricle (RV). The only outlet from the left ventricle (LV) is a ventricular septal defect (VSD). DORV is usually associated with concordant atrioventricular (AV) connections (ie, the right atrium drains into the RV and the left atrium drains into the LV). Fibrous discontinuity is present between the mitral and semilunar valves, which is referred to as subpulmonic and subaortic conus.

DORV is virtually always associated with a VSD and occasionally with an atrial septal defect. Patients with DORV may also present with varying degrees of left ventricular hypoplasia and mitral valve anomalies such as stenosis or atresia. Straddling of the AV valves across the VSD may be present. The aortic valve may be stenosed, and the aortic arch may show coarctation or even interruption. Anomalies of the coronary arteries (CA) such as those that occur in patients with dextro-transposition of the great arteries (D-TGA) may be present. These include the left circumflex arising from the right main, a single right CA, a single left CA, and inverted origin of the CA.

Finally, the AV node and His-Purkinje fibers may be displaced in DORV because of the anatomic characteristics of these hearts.

In DORV, the great arteries may take different relationships as follows:

In 64% of cases of DORV, the great arteries lie side by side with the AO to the right of the PA and both semilunar valves lying in the same transverse and coronal plane (physiologically similar to tetralogy of Fallot [TOF]).
In 26% of cases of DORV, the AO is anterior and to the right of the PA, physiologically resembling transposition of the great arteries (TGA), ie, D-TGA, with a VSD.
In 7% of cases of DORV, the AO is anterior and to the left of the PA (left transposition of great artery [L-TGA]).
Only 3% of cases of DORV have a normal great artery relationship with the AO arising posterior and to the right of the PA.

Pathophysiology: The pathophysiology of DORV is variable, irrespective of the great arterial relationship (ie, side by side, D-TGA, L-TGA, normally related). Clinical manifestations may range from that of a large VSD to that of TGA and depend mostly on the position of the VSD in relation to the great vessels (whether it is subpulmonary or subaortic) and the presence or absence of pulmonary valve stenosis (PS). Both of these factors contribute substantially to the hemodynamics of this congenital heart defect.

In cases of a subaortic VSD, which occurs in 60-70% of patients, the VSD is closer to the aortic valve, thus oxygenated blood from the LV is directed to the AO and desaturated blood from the right atrium (RA) is directed primarily to the PA (see Image 1). PS occurs commonly and directs some desaturated blood into the AO. Because of the large VSD, the RV and the LV as well as the AO handle equal systolic pressures. When PS is present, this poses a restriction to flow to the pulmonary circuit, and thus, systolic pressure in the pulmonary arteries is lower. This physiology resembles that of TOF with cyanosis and no congestive heart failure (CHF).

In cases of a subaortic VSD with no PS, systolic pressure in both great vessels as well as in both ventricles is equal; thus, blood follows the path of least resistance (ie, usually towards the lungs) and the clinical picture is that of a large VSD. The degree of blood oxygenation in the systemic as well as the pulmonary circuits is determined by degree of mixing in the systemic (ie, right) ventricle, which in turn depends on the degree of resistance upstream of the pulmonary valve.

All patients with elevated pulmonary blood flow (PBF) at systemic or near systemic pressures are at increased risk of developing early pulmonary obstructive vascular disease regardless of their arterial oxygen saturation (ie, presence or absence of cyanosis).

With a subpulmonary VSD (Taussig-Bing anomaly), which occurs in 10% of patients, oxygenated blood from the LV is directed to the PA and desaturated blood from the RA is directed to the AO. This physiology resembles TGA with a VSD; thus, the patient presents with cyanosis and CHF.

In cases of a doubly committed VSD, the left ventricular outflow is not committed preferentially to either semilunar valve. In the presence of PS, the physiology resembles that of TOF, and in the absence of PS, it is that of a large VSD.

In remote VSD, the VSD is far from both semilunar valves. It is most commonly an AV canal-type VSD. Again, the physiology is that of TOF in cases involving PS and is that of a large VSD when flow through the pulmonary valve is not restricted (ie, absence of PS).

Frequency:

In the US: Congenital heart disease (CHD) occurs in less than 1% of all newborns, and DORV is present in 0.5-1.5% of all patients with CHD. The estimated frequency of DORV is 1 case per 10,000 live births.
DORV and truncus arteriosus occur with a higher incidence in the offspring of mothers with diabetes mellitus than in the general population. Teratogenic mechanisms involved are obscure, although in pregnant diabetic rats, antioxidant supplementation with vitamin E reduced the severity of malformations in their offspring.

Mortality/Morbidity: Mortality and morbidity are dependent not only on the overall clinical condition of the patient but also on the type and severity of associated anomalies.

Irrespective of the great vessel relationship, the mortality rate is less than 5% for simple subaortic VSD and is somewhat higher for a doubly committed VSD.

In cases of subpulmonary VSD (Taussig-Bing anomaly), morbidity and mortality depend on whether the patient has already developed pulmonary vascular obstructive disease and also on the type of surgery that is required. In cases of DORV with D-TGA, creation of an intraventricular tunnel between the VSD and the AO carries a mortality risk of 10-15%. In subpulmonary VSD with PS (ie, TOF-type physiology), an intraventricular tunnel between the VSD and the AO in addition to relief of PS by a patch graft also carries a mortality risk of 10-15%. In cases of remote VSD, the preferred surgical repair is creation of an interventricular tunnel between the VSD and the AO. However, it carries a mortality rate as high as 30-40%.

When the above surgical procedures cannot be performed (ie, hypoplastic LV, inadequate anatomy for an intracardiac conduit between the LV and the AO, hypoplastic AO, hypoplastic mitral valve), a Fontan-type operation is the choice; the mortality rate has decreased to approximately 5%.

Sex: No sex predilection is reported.

Age: Newborns usually present with this entity; however, in some circumstances such as subaortic VSD with mild-to-moderate PS, the diagnosis may not be made until later in infancy.

CLINICAL

History: History of fetal bradycardia heart block during the first trimester of pregnancy has been associated with DORV (as opposed to autoimmune causes of fetal heart block, which occur after the second and third trimesters). Fetal heart block can be diagnosed ultrasonographically depending on the subtype of DORV (eg, with or without TGA); clinical history differs. In patients with DORV and TGA, the clinical presentation depends on the location of the VSD and the presence of PS, the degree of PS, or both.

If the VSD is subpulmonic, the physiology resembles that of TGA with VSD. Patients with this anatomy usually present in the newborn period or within the first few weeks of life with cyanosis and signs of pulmonary overcirculation.

If the VSD is subaortic, the patient may be only mildly cyanotic and may present primarily with pulmonary overcirculation at 3-6 weeks of life when pulmonary vascular resistance drops. If PS is present (which often is the case in DORV with subaortic VSD), the degree of PS greatly affects clinical presentation.

If PS is mild or moderate, the patient may present with mild cyanosis and little or no pulmonary overcirculation.

If PS is severe, clinical presentation resembles that of TOF. Cyanosis from diminished PBF is likely to be the major clinical feature.

In patients with DORV and TGA (both uncommon lesions), the VSD may be doubly committed or remote from the great arteries.

If the VSD is doubly committed, the conus septum is deficient and the VSD usually lies above the crista supraventricularis closely related to both semilunar valves. Clinical presentation often is that of DORV with a subpulmonic VSD, although the patient may have slightly higher systemic oxygen saturation.

In DORV with TGA and remote VSD, many variables determine clinical presentation. If the VSD is remote from both semilunar valves, it often is part of an AV canal-type defect, in which case many other anomalies are likely.

Alternatively, multiple muscular VSDs may be remote from the semilunar valves. Clinical presentation depends on factors such as the location of the VSDs, the presence or absence of PS (right ventricular outflow tract obstruction), and the direction of streaming of blood flow through VSDs.

Physical: Physical findings vary, depending on the location of the VSD and the presence or absence of PS.

With a subaortic VSD and no PS, cyanosis is mild or absent.

PBF is increased, thereby producing CHF.

The precordium is hyperactive with a loud second heart sound, which may appear to be single.

Harsh regurgitant systolic murmur is heard as pulmonary vascular resistance decreases.

Clinically, these patients resemble those with a large VSD.

In DORV with subaortic VSD and PS, physical findings depend on the degree of PS.

If PS is mild, little cyanosis and only mild CHF may be present.
These patients present with a murmur from PS (systolic ejection murmur), from the VSD (regurgitant murmur), or both.

If PS is moderate or severe, cyanosis is prominent because of decreased PBF (resembling TOF).
If uncorrected, cyanosis leads to late findings such as polycythemia and digital clubbing.

In those patients with subpulmonic VSD (PS is rare in these patients), PBF increases as vascular resistance falls.

These patients present similarly to those with TGA and VSD.

Cyanosis is prominent early, and pulmonary overcirculation develops.

Failure to thrive is likely to develop if treatment is not instituted.

The second heart sound is loud and possibly single, and a regurgitant systolic murmur develops.

If increased pulmonary vascular resistance occurs, signs of CHF diminish and the murmur decreases.

An ejection click may appear along with a diastolic murmur of pulmonary valve insufficiency (late findings).

Patients with doubly committed VSD also present similarly to those with TGA and VSD.

Cyanosis may be mild.

Signs of CHF, including tachypnea, tachycardia, and hepatomegaly, lead to failure to thrive.

Causes:

DORV may be part of complex CHD in patients with DiGeorge, velocardiofacial, and conotruncal anomaly-face syndromes. It has also been associated with trisomies 13 and 18 and tetrasomy 8p.

DORV may be associated with other organ-system defects, such as 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).

DORV has recently been reported to occur in mouse embryos homozygous for the JMJ mutation, which affects the nuclear protein jmj coded by chamber-specific genes.

DORV has also been reported in patients with mutations in human cardiac transcription factor NKX2.5.

DIFFERENTIALS

Truncus Arteriosus
Ventricular Septal Defect, General Concepts

Other Problems to be Considered:

Distinguish DORV (with or without TGA) and subaortic VSD from VSD.
PS may have a presentation similar to that of TOF.
Subpulmonary VSD without PS may have a presentation similar to that of TGA with VSD.

WORKUP

Lab Studies:

Clinical laboratory studies (ie, hematologic analysis, urinalysis) are not likely to be of diagnostic help; late findings may include polycythemia, but this and other findings of chronic cyanosis are nonspecific.

Imaging Studies:

Echocardiography is used to evaluate anatomy, hemodynamics, and function of the heart after surgical repair or palliation, and it is the most important means of establishing diagnosis of DORV with TGA. Four important findings to determine DORV are as follows:

Both great arteries arise from the RV.

AO is to the right of or anterior to the PA.

No course of egress of blood from the LV other than a VSD is present.

Discontinuity of mitral and semilunar valves is present.

Chest radiography may provide valuable clues for the diagnosis of DORV with TGA.

Chest radiography for patients with either subaortic or subpulmonary VSD without PS shows cardiomegaly with increased pulmonary vascular markings; the main PA segment may be prominent. These findings are not specific for DORV.

If PS is present, chest radiography shows a normal heart size and normal-to-decreased pulmonary vascular markings.

Magnetic resonance imaging (MRI) may serve as an adjunct tool to echocardiography for determination of visceral and atrial situs, although it is rarely used as a primary diagnostic tool for infants with suspected CHD. In some patients with DORV with remote VSD, MRI may aid in defining the spatial relationship between VSD and the semilunar valves.

Angiography may add anatomic and physiologic details to information found by echocardiography.

Other Tests:

ECG in patients with DORV with TGA shows no specific findings.

Usually, normal sinus rhythm and possible prolonged P-R interval are present. Right axis deviation and right ventricular hypertrophy (RVH) are likely to be present.

In the absence of these findings, question the diagnosis or consider special circumstances such as an associated AV canal if left axis deviation is present.

Some ECG variations may exist depending on the variety of DORV with TGA.
- ECG in patients with subaortic VSD with no PS may show superior QRS axis (-30° to -170°) with either RVH or biventricular hypertrophy and left atrial enlargement. First-degree AV block may be present with this lesion.
- ECG in patients with subpulmonic VSD or in those with subaortic VSD and PS shows right axis deviation, RVH, and often right atrial enlargement.

Procedures:

Echocardiography has mostly eliminated the need to perform cardiac catheterization in these patients; however, catheterization may still be necessary in certain circumstances. Catheterization may be required for the following reasons:

Need for further definition of coronary artery anatomy

Need to determine coexistent conditions that cannot be elucidated by echocardiography

Need to confirm restrictive VSD by measuring ventricular pressures

Need to determine pulmonary vascular resistance (and reactivity) in patients suspected of having increased resistance

TREATMENT

Medical Care: Direct medical treatment depends on the clinical presentation, which is determined by the different physiology of each type of DORV.

In DORV with no PS, direct medical management at reducing CHF to improve the patient’s condition prior to surgery. Management of CHF requires medications such as loop diuretics (eg, furosemide), potassium-sparing diuretics (eg, spironolactone), and digitalis. In addition, observe subacute bacterial endocarditis prophylaxis.

Infants with a subpulmonary 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 patients with DORV and PS with marked cyanosis and hypoxemia, initial medical management consists of increasing the fraction of inspired oxygen (FIO₂), which may be up to 100%. This decreases pulmonary vascular resistance, thereby increasing the amount of blood flow in the lungs with consequent increase in overall organ oxygenation.

Surgical Care: Two surgical approaches are appropriate, depending on the degree of CHF.

Palliative surgery

As with medical treatment, this approach helps improve the patient's clinical condition, allowing him or her to gain weight to 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 PA banding to decrease PBF.

Patients with subaortic or subpulmonary VSD with PS are cyanotic and have decreased PBF; therefore, perform a systemic-to-PA shunt to increase PBF.

Definitive surgery

The relationship of VSD to the great arteries and the distribution of 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 AV valves and/or severe underdevelopment of LV), a Fontan-type operation is an option with redirection of systemic (deoxygenated) blood into the PA without traversing a ventricle.

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 the lower 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-AO by virtue of the switch.

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. In a recent report from the Children’s Hospital of Pittsburgh, 15.4% of patients undergoing transplant were born with some form of DORV. These patients require lifelong immunosuppression and close follow-up care.

Consultations: As with any other form of CHD, parents of patients born with DORV and TGA may meet with a geneticist to discuss the possibility of subsequent children having this or other forms of CHD.

Activity:

Patients with DORV and TGA 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.

MEDICATION

Medical therapy is aimed at alleviating CHF, when present, to prepare patients for surgery.

Drug Category: Loop diuretics -- Furosemide is used to decrease pulmonary congestion in patients with pulmonary overcirculation.

Drug Name
Furosemide (Lasix) -- Inhibits absorption of sodium and chloride in proximal and distal tubules of the loop of Henle, thereby promoting excretion of salt and water.
Adult Dose 20-80 mg/d PO/IV divided q6-12h; not to exceed 600 mg/d
Pediatric Dose 0.5-2 mg/kg/dose PO/IV/IM q8-24h; not to exceed 6 mg/kg/d PO or 2 mg/kg/dose IV
Contraindications Documented hypersensitivity; hepatic coma; anuria; severe electrolyte depletion
Interactions Antagonizes muscle-relaxing effect of tubocurarine; auditory toxicity appears to be increased with coadministration of aminoglycosides and furosemide; hearing loss of varying degrees may occur; anticoagulant activity of warfarin may be enhanced when taken concurrently with this medication; increased plasma lithium levels and toxicity are possible when taken concurrently with this medication
Pregnancy C - Safety for use during pregnancy has not been established.
Precautions May be ototoxic in patients with oliguria; may cause electrolyte imbalance with hypokalemic-hypochloremic metabolic alkalosis, hyponatremia, hypomagnesemia, and hypocalcemia; prolonged use in premature infants may precipitate nephrocalcinosis from hypercalciuria; these effects can be avoided by concomitant use of potassium-sparing diuretics (eg, spironolactone)

Drug Category: Potassium-sparing diuretics -- Potassium-sparing diuretics (eg, spironolactone) are weak diuretics usually prescribed with more potent loop diuretics to prevent potassium depletion with subsequent development of hypokalemic-hypochloremic metabolic alkalosis.

Drug Name
Spironolactone (Aldactone) -- Inhibits aldosterone-dependent sodium-potassium exchanger in distal convoluted renal tubule, thereby retaining potassium and promoting excretion of sodium and water.
Adult Dose 25-100 mg/d PO divided bid/qid; not to exceed 200 mg/d
Pediatric Dose 1-3.3 mg/kg/d PO divided bid/qid; not to exceed 200 mg/d
Contraindications Documented hypersensitivity; anuria; renal failure; hyperkalemia
Interactions May potentiate antihypertensive drugs; may provoke severe hyperkalemia when administered with ACE inhibitors or indomethacin; increases half-life of digoxin, thereby augmenting its risk of toxicity
Pregnancy D - Unsafe in pregnancy
Precautions May cause mild metabolic acidosis, GI distress, rashes, and gynecomastia; few cases of agranulocytosis have been reported; caution in renal and hepatic impairment

Drug Category: Inotropic agents -- Positive inotropic agents increase the force of contraction of the myocardium and are used to treat acute and chronic CHF. Some may also increase or decrease the heart rate (ie, positive or negative chronotropic agents), provide vasodilatation, or improve myocardial relaxation. These additional properties influence the choice of drug for specific circumstances. Those used predominantly for their inotropic effects include cardiac glycosides. Digitalis glycosides are used for their inotropic properties in the presence of left ventricular failure.

Drug Name
Digoxin (Lanoxin, Lanoxicaps) -- Digitalis glycoside. Enhances myocardial contractility by inhibition of Na⁺/K⁺ ATPase, a cell membrane enzyme that extrudes Na and brings K into the myocyte. Resulting increase in intracellular Na stimulates Na-Ca exchanger in the cell membrane, which extrudes Na and brings in Ca, therefore increasing contractility of myocyte (ie, positive inotropic effect).
Adult Dose Digitalizing dose:
10-15 mcg/kg/d PO divided tid for 3 doses (typically 0.75-1.5 mg total dose)
8-12 mcg/kg/d IV/IM divided tid for 3 doses (typically 0.5-1 mg total dose)
Maintenance dose:
2.5-5 mcg/kg/d PO (typically 0.125-0.5 mg/d)
2-3 mcg/kg/d IV/IM (typically 0.1-0.4 mg/d)
Pediatric Dose Total digitalizing dose (TDD):
Premature infants: 0.02 mg/kg PO divided q8h
Full-term infants: 0.03 mg/kg PO divided q8h
1-24 months: 0.04-0.05 mg/kg PO divided q8h
>24 months: 0.03-0.04 mg/kg PO divided q8h
Maintenance dose:
Infants: 6-8 mcg/kg/d PO bid dosing is recommended
2-5 years: 10-15 mcg/kg/d PO bid dosing is recommended
5-10 years: 7-10 mcg/kg/d PO bid dosing is recommended
>10 years: 3-5 mcg/kg/d PO
Therapeutic concentration 0.8 - 2 = ng/mL
Contraindications Documented hypersensitivity; beriberi heart disease; idiopathic hypertrophic subaortic stenosis; constrictive pericarditis; carotid sinus syndrome
Interactions IV calcium may produce arrhythmias in digitalized patients; medications that may increase digoxin levels include alprazolam, benzodiazepines, bepridil, captopril, cyclosporine, propafenone, propantheline, quinidine, diltiazem, aminoglycosides, PO amiodarone, anticholinergics, diphenoxylate, erythromycin, felodipine, flecainide, hydroxychloroquine, itraconazole, nifedipine, omeprazole, quinine, ibuprofen, indomethacin, esmolol, tetracycline, tolbutamide, and verapamil; medications that may decrease serum digoxin levels include aminoglutethimide, antihistamines, cholestyramine, neomycin, penicillamine, aminoglycosides, PO colestipol, hydantoins, hypoglycemic agents, antineoplastic treatment combinations (including carmustine, bleomycin, methotrexate, cytarabine, doxorubicin, cyclophosphamide, vincristine, and procarbazine), aluminum or magnesium antacids, rifampin, sucralfate, sulfasalazine, barbiturates, kaolin/pectin, and aminosalicylic acid
Pregnancy C - Safety for use during pregnancy has not been established.
Precautions Symptoms of digitalis intoxication include changes in cardiac rhythm, especially induction of ectopic pacemakers and impaired conduction (eg, complete heart block), GI symptoms (eg, anorexia, nausea, emesis), and other symptoms (eg, fatigue, weakness, blurred vision, aberrations of color vision, headache, somnolence, disorientation, seizures); patients with deceased renal function and those with hypokalemia, hypomagnesemia, and hypercalcemia may reach toxic levels at lower doses; in patients with Wolff-Parkinson-White who develop atrial flutter or fibrillation, treatment with digoxin rarely may provoke ventricular fibrillation by increasing antegrade conduction through accessory pathway; if cardioversion or calcium infusion is required, administer lidocaine first to avoid possibility of ventricular fibrillation

FOLLOW-UP

Further Inpatient Care:

Maintain patency of the ductus arteriosus with prostaglandin E1 in newborns with markedly diminished PBF from severe PS. In newborns with DORV and TGA who have subpulmonic VSD, performing balloon atrial septostomy to enhance mixing of systemic and pulmonary circulations until surgery can be performed may be necessary.

Further Outpatient Care:

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.

In all patients, subacute bacterial endocarditis prophylaxis is required.

Transfer:

Because surgery in these patients often is technically demanding, strongly consider referring these patients to a center with a large pediatric cardiac surgical program.

Prognosis:

Improvement in surgical techniques in recent years has resulted in good outcomes for most patients born with CHD. Prognosis for infants born with DORV and TGA generally is good, although it is dependent on specific anatomy. For example, patients with DORV and TGA with a subaortic VSD and no other anatomic abnormalities (eg, left ventricular hypoplasia) are likely to do well after surgery. Patients with restrictive VSD may not do as well because this is a particularly difficult problem. Enlargement of VSD is difficult and likely to result in complications, such as conduction abnormalities (AV block).

MISCELLANEOUS

Medical/Legal Pitfalls:

Medicolegal pitfalls in caring for patients with DORV and TGA are similar to those for any patient with CHD.

Failure to make the correct diagnosis is of paramount importance. The correct treatment plan can be determined only if all anatomic details are known. Misdiagnosis can lead to inappropriate care.

The second issue is surgery. Because most of these patients do well when care is administered at a center with considerable experience in caring for infants with CHD, referral to such a center provides the best opportunity for a good long-term outcome.

The physician must be familiar with the possible complications that may result from surgery and be able to treat complications resulting from surgery appropriately.

Special Concerns:

Subaortic or subpulmonary VSD without PS: If left unrepaired, these infants develop CHF from pulmonary overcirculation, which evolves into pulmonary vascular obstructive disease.

Subaortic or subpulmonary VSD with PS: If left untreated, complications develop, including cyanosis (ie, polycythemia), which can lead to stroke.

PICTURES

Caption: Picture 1. Double outlet right ventricle (DORV) with transposition of 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).

Picture Type: Image

Caption: Picture 2. This is an angiogram obtained during catheterization of a patient with double outlet right ventricle (DORV) with transposition of 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.

Picture Type: X-RAY

Caption: Picture 3. This is an angiogram obtained during catheterization of a patient with double outlet right ventricle (DORV) with transposition of great arteries (see Image 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.

Picture Type: X-RAY