Double Outlet Right Ventricle

Summary of DORV

Double Outlet Right Ventricle (DORV) is a group of congenital heart defects where both great arteries (the aorta and the pulmonary artery) arise exclusively or predominantly from the right vSummary entricle (RV). A ventricular septal defect (VSD) is almost always present. In classifying DORV, if a great vessel overrides the ventricular septum, the type of connection is determined using the 50% rule, meaning more than 50% of the vessel's circumference must be committed to the RV for it to be considered arising from the RV. While the historical definition required a well-developed conus beneath both great arteries, the currently accepted definition is broader and includes various arrangements of the subarterial conus. Absence of aorto-mitral continuity may also be used from a morphological standpoint. This condition may present in various spectrum. DORV-Tetralogy of Fallot type has the LVOT committed more than 50% to the right ventricle with an associated pulmonary stenosis. The DORV-TGA subtype has inversion of great vessels. More on DORV here and here.

Anatomy and Morphology 

DORV is a highly variable set of anomalies. Key anatomical features include the relationship of the great vessels to each other and to the ventricular cavity, and critically, the location and size of the ventricular septal defect (VSD). VSDs in DORV are usually large. The position of the infundibular septum influences the VSD location.

Classification schemes often categorize DORV based on the VSD location relative to the great arteries. Common types described include:

• Subaortic VSD: The VSD is located beneath the aorta. This is the most common type.

• Subpulmonary VSD: The VSD is located beneath the pulmonary artery. The Taussig-Bing malformation is a variant of DORV with a subpulmonary VSD.

• Doubly Committed VSD: The VSD is located beneath both great arteries. This results from absent or markedly attenuated infundibular septum. These defects are close to both semilunar valves and may be referred to as juxta-arterial.

• Remote (Noncommitted) VSD: The VSD is located far from both great arteries. This can include perimembranous inlet or muscular defects. Defects of this type are sometimes associated with Atrioventricular Septal Defects (AVSD).

The relationship of the great arteries to each other is also variable. Normal relations (aorta posterior and right of the pulmonary artery) are most common. Parallel arrangements are also seen. In most DORV hearts, the aortic and pulmonary valves are situated at the same level, unlike normal hearts, due to the presence of a muscular conus under each great artery.

Physiology and Clinical Presentation 

The physiology of DORV is diverse and depends heavily on the location of the VSD and whether there is pulmonary or systemic outflow obstruction. It can resemble the physiology of a simple VSD, Tetralogy of Fallot (TOF), or Transposition of the Great Arteries (TGA).

• VSD-type physiology (typically with subaortic or doubly committed VSD and no pulmonary stenosis) presents with signs of congestive heart failure, usually within the first 4–6 weeks of life.

• TOF-type physiology (typically with subaortic VSD and pulmonary stenosis) presents with cyanosis. There is often a short systolic ejection murmur due to stenotic RVOT flow.

• TGA-type physiology (typically with subpulmonary VSD, like Taussig-Bing anomaly) presents with cyanosis due to reduced effective pulmonary blood flow. If associated with coarctation of the aorta (CoA) or interrupted aortic arch (IAA), neonates may present with severe heart failure, respiratory distress, and low cardiac output.

• Systemic outflow obstruction (e.g., subpulmonary VSD with aortic arch obstruction) presents with signs of low cardiac output neonatally.

• Single ventricle physiology can occur in some complex forms, such as DORV with heterotaxy, leading to cyanosis with complete mixing of blood.

Associated Lesions DORV can be associated with a variety of other cardiac anomalies. These include:

• Pulmonary valvar or infundibular stenosis.

• Aortic obstruction, such as subaortic stenosis, Coarctation of the Aorta (CoA), or Interrupted Aortic Arch (IAA).

• Atrioventricular Septal Defects (AVSD).

• Hypoplastic ventricle, leading to functional single ventricle physiology.

• Atrioventricular discordance (ccTGA).

• Pulmonary atresia.

• Right atrial isomerism (heterotaxy).

• Total Anomalous Pulmonary Venous Drainage (TAPVD).

• Unusual coronary artery patterns are seen in about 60% of cases. Identifying these, especially courses anterior to the RVOT, is important for surgical planning.

Diagnosis 

Diagnosis of DORV is primarily made through imaging studies.

• Echocardiography is the mainstay and usually diagnostic. It is used to determine the location and size of the VSD, the relationship of the great arteries and AV valves to the ventricles, the presence of outflow obstruction, and associated defects. Fetal echocardiography can detect DORV and associated findings like pulmonary stenosis and evaluate for potential 22q11 deletion syndrome.

• Electrocardiography (ECG) findings are non-characteristic and variable. It may show signs of atrial enlargement or right ventricular hypertrophy (RVH), sometimes left-axis deviation if associated with AVSD.

• Chest X-ray (CXR) reflects the underlying physiology. It can show cardiomegaly and pulmonary vascularity which varies depending on the presence of pulmonary stenosis.

• Cardiac Magnetic Resonance Imaging (MRI) and Computed Tomography (CT) may be used to provide detailed anatomical information, particularly regarding the aortic arch, pulmonary arteries, and coronary arteries, especially when echocardiography is insufficient. CT is sometimes considered a second choice for cross-sectional imaging. MRI can also be used to quantify ventricular volumes and shunts.

• Cardiac Catheterization is rarely needed solely for diagnosis. It may be used to assess pulmonary vascular resistance, especially in older patients or those with suspected pulmonary hypertension, to determine operability.

Management and Surgical Strategy 

Management of DORV is complex and highly variable due to the wide spectrum of anatomy and physiology. The position of the VSD relative to the great vessels is a key factor in determining the surgical approach.

• The goal is often to achieve an unobstructed concordant ventriculoarterial connection, though this may not always be feasible.

• Biventricular repair is generally considered optimal when possible. This usually involves closing the VSD and creating an unobstructed pathway from the left ventricle (LV) to the aorta. The VSD may need enlargement to ensure unobstructed flow.

• For simple DORV with subaortic VSD, repair involves VSD closure and rerouting to the aorta.

• For DORV with subpulmonary VSD (Taussig-Bing), repair typically involves VSD closure (rerouting the PA to the LV) and an Arterial Switch Operation (ASO).

• For DORV with Remote VSD, biventricular repair may be attempted, but a single ventricle palliation (Fontan) may be necessary if a complex intraventricular tunnel would be required. Atrial switch procedures may be used in rare cases with AV discordance.

• Alternative biventricular repair procedures like REV/Lecompte or Nikaidoh may be used for complex anatomy.

• If biventricular repair is not possible, patients are managed with a staged single ventricle palliation pathway, culminating in the Fontan circulation. Initial palliation may include BTT shunts, ductal stenting, or pulmonary artery banding.

Timing of intervention varies depending on the specific anatomy and physiology, ranging from neonatal repair to 2-4 months of age.

Outcome Outcomes for patients with DORV are generally good across the spectrum of lesions, but are less favourable in specific subgroups. Patients with outflow tract obstructions and associated arch hypoplasia have worse outcomes. Outcomes are also worse for those managed as single ventricle patients. Potential long-term issues after repair can include residual or recurrent outflow tract obstruction, ventricular dysfunction, pulmonary hypertension, and arrhythmias.

References

1. Abdulla R, Abdulla R, Awad S, Al-kubaisi M, Muller B, Taqatqa A, et al., editors. Pediatric Electrocardiography: An Algorithmic Approach to Interpretation. Springer International Publishing Switzerland; 2016.

2. Dipchand AI, Almond C, Breatnach C, Dipchand AI, Floh AA, Honjo O, et al., editors. Manual of Cardiac Care in Children. Springer Nature Switzerland AG; 2024.

3. Park IS, editor. An Illustrated Guide to Congenital Heart Disease: From Diagnosis to Treatment – From Fetus to Adult. Springer Nature Singapore Pte Ltd; 2019.

4. Batisse A, Fermont L, Lévy M. Cardiologie pédiatrique pratique: Du fœtus à l’adulte. 4e édition. Rueil-Malmaison Cedex: DOIN EDITEURS Wolters Kluwer France; 2013.

5. Legmann P, Bonnin-Fayet P, Convard J-P, Seguin G. Échographie. 4e édition. Collection Imagerie médicale, formation. 2008.

6. Klimczak C. Échocardiographie clinique. 5e édition. Collection de cardiologie pratique. 2006.

7. Body G, Perrotin F, Guichet A, Paillet C, Descamps P. La pratique du diagnostic prénatal. 2002.

8. Saliba E, Hamamah S, Benhamed M, Gold F. Médecine et biologie du développement. 2001.

9. Rigby ML, Anderson RH, editors. Echocardiography in Congenital Heart Disease Made Simple. Oxford: Blackwell Publishing; 2005.

10. Rudolph AM. Congenital Diseases of the Heart: Clinical-Physiological Considerations. 3rd ed. Chichester: Wiley-Blackwell; 2009.

11. Alboliras ET, Hijazi ZM, Lopez L, Hagler DJ, editors. Visual Guide to Neonatal Cardiology. Hoboken, NJ: Wiley; 2018.

Echocardiographic Example 1 - DORV - TOF type

Parasternal long axis showing that the aorta is overriding and committed to the right ventricle. 

Parasternal long axis shows that the pulmonary valve is unobstructed.

Echocardiographic Example 2 - DORV - TOF type

Zoom on the RVOT and pulmonary valve. The leaflets are opening and closing. There is anterograde. The MPA is smaller than usual for a term infant. 

The RPA and LPA are confluent. We can observe some of the "red flash" from the tortuous small PDA that is left to right. 

Pulmonary veins are seen draining into the left atrium.

Apical views. We can appreciate the perimembranous VSD with the overriding aorta, mostly committed to the RV. The coronary sinus drains into the right atrium. There is adequate RV and LV systolic function and dimensions. 

Anterior tilt outlining the RVOT. We can also appreciate a small trabecular VSD. 

Zoom on the RVOT. One may appreciate the red flow from the ductus arteriosus from this view, entering the MPA. 

Gradient is between 20-30 mmHg accross the RVOT. 

2D and Colour in the 4 chamber view. There is trivial atrio-ventricular valvular insufficiency on the right side. Sweep outlines the flow through the perimembranous VSD to the aorta. There is then the flow from the RV to the RVOT with acceleration / turbulence. 

TET views

Views below outline the RV inflow, trabeculary body and outflow tract in the posterior to anterior view from the subcostal region (and apical region). This view helps outlining the central overriding aorta, as well as the anterior narrowed RVOT leading to the pulmonary valve and main pulmonary artery. 

Subcosal short axis - Arch view, SVC to RA, IVC to RA. 

DORV-TGA - Taussig-Bing Anomaly

Taussig-Bing anomaly is a rare, complex congenital heart defect characterized by double outlet right ventricle (DORV) with a subpulmonary ventricular septal defect (VSD) and side-by-side great arteries. In this condition, both the aorta and pulmonary artery originate from the right ventricle. The subpulmonary VSD, located beneath the pulmonary artery, is a key feature. 

• Double Outlet Right Ventricle (DORV): Both the aorta and pulmonary artery arise from the right ventricle. 

• Subpulmonary Ventricular Septal Defect (VSD): A VSD exists in the wall separating the ventricles, specifically positioned beneath the pulmonary artery. 

• Side-by-side great arteries: The aorta and pulmonary artery are positioned next to each other instead of their normal arrangement. 

• Associated Anomalies: Taussig-Bing anomaly can be associated with other heart defects, such as aortic coarctation, arch hypoplasia, and coronary artery anomalies.

1. Definition

Double Outlet Right Ventricle (DORV) is a complex congenital heart disease characterized by both great arteries primarily arising from the right ventricle (RV). To be classified as DORV, at least 50% of the aorta must be committed to the RV. Unlike other conditions where a semilunar valve might be in fibrous continuity with an atrioventricular (AV) valve, in DORV, neither semilunar valve is typically in fibrous continuity with an AV valve, although some definitions allow for mitral-aortic or mitral-pulmonic continuity. An obligatory ventricular septal defect (VSD), which can be subaortic or subpulmonic, allows blood flow from the left ventricle (LV) to the great arteries. Pulmonary stenosis may or may not be associated. The great vessels usually arise side-by-side, with the aorta to the right and semilunar valves at the same horizontal level, although their relationship can vary.

The Taussig-Bing Anomaly is a specific variant of DORV. It is defined as DORV with dextro-transposition of the great arteries (d-TGA), where the pulmonary artery (PA) overrides the VSD and the LV. More specifically, it is characterized by DORV with a subpulmonary VSD. In this anomaly, 100% of the aorta arises from the RV, and more than 50% of the PA arises from the LV. It can also be described as TGA with a subpulmonic VSD, often featuring side-by-side great vessels and potential obstruction to the aorta and aortic arch.

2. Classification

The international nomenclature recognizes four types of DORV: VSD-type, Tetralogy of Fallot (TOF)-type, TGA-type, and Non-Committed-type. The Taussig-Bing anomaly falls under the TGA-type DORV, specifically identified by a subpulmonary VSD. The location of the VSD is a key classification criterion for DORV, including:

• Subaortic (most common): Where the infundibular septum is attached to the anterior limb of the septomarginal trabecula.

• Subpulmonary (Taussig-Bing): Where the infundibular septum is attached to the posterior limb of the septomarginal trabecula. This type accounts for approximately 10% to 30% of DORV cases.

• Doubly committed: Where the VSD is closely related to both semilunar valves, usually above the crista supraventricularis (<5% of cases).

• Remote: Where the VSD is clearly distant from the semilunar valves, often representing an AV canal-type VSD or an isolated muscular VSD. Atrial isomerism is commonly seen with this type.

Cardiac development initially begins with a DORV-like anatomy, where the truncus arteriosus is connected to the bulbus cordis, the precursor of the right ventricle. DORV can result from inadequate torsion and rotation of the truncus and insufficient absorption of the distal posterior bulbar segment, though morphogenesis is multifactorial.

3. Pathophysiology

The physiology and clinical presentation of DORV are highly variable, with some cases resembling TOF, TGA, or a simple VSD. In the Taussig-Bing anomaly, the hemodynamics and clinical manifestations are similar to complete TGA with a VSD. Due to streaming effects, the left-to-right shunt through the subpulmonary VSD preferentially directs oxygenated blood to the pulmonary artery, while the aorta receives deoxygenated blood from the RV. This results in a TGA-like clinical picture.

4. Clinical Manifestations

• Cyanosis: Due to the preferential streaming of deoxygenated blood to the aorta. Differential cyanosis is uncommon because of the common association with a VSD.

• Heart Failure: Symptoms such as respiratory distress, tachypnea, poor feeding, and growth failure are common due to excessive pulmonary blood flow.

• Physical Examination: Increased precordial activity, a prominent second heart sound, and a precordial murmur may be present, similar to tricuspid atresia with VSD. If pulmonary stenosis (PS) is also present, the signs might resemble TOF. In the presence of severe pulmonary hypertension with a bidirectional shunt, the systolic murmur may not be loud.

5. Associated Lesions

The Taussig-Bing anomaly (DORV with subpulmonary VSD) is characterized by an obligatory VSD. Other commonly associated lesions include:

• Pulmonary Stenosis: May or may not be associated. If present, it causes signs similar to TOF.

• Aortic Arch Obstruction: This includes coarctation of the aorta (CoA) and arch hypoplasia, which are frequently associated with Taussig-Bing anomaly. Its presence strongly suggests Taussig-Bing anomaly, though it doesn't completely exclude transposition.

• Coronary Artery Patterns: Unusual coronary patterns are seen in 60% of cases, with retropulmonary circumflex being the most common.

• DiGeorge Syndrome: This is a common association, linked to a chromosome 22q11 deletion. Features include abnormal facies, congenital heart defects, and absence or hypoplasia of the thymus (leading to immune deficiency and hypocalcemia). Serum calcium and magnesium levels should be checked, and irradiated blood products may be necessary for urgent surgery due to potential immune deficiency.

• Other general DORV associations: Hypoplastic ventricle (functional single ventricle), Atrioventricular discordance, congenitally corrected TGA (ccTGA), Pulmonary atresia, Right atrial isomerism, Total Anomalous Pulmonary Venous Drainage (TAPVD), and Atrioventricular Septal Defects (AVSD).

• Multiple VSDs can also occur.

6. Diagnostic Studies

• Echocardiography: This is the most important diagnostic tool. It adequately delineates the anatomy in a high percentage of cases. It can directly image the defect and assess flow patterns using color Doppler. Differentiation between aortopulmonary transposition with a large VSD and Taussig-Bing anomaly can be challenging, but in Taussig-Bing, there is typically a separation between the mitral and pulmonary valves due to a subpulmonary infundibulum.

• Electrocardiography (ECG): Findings are non-characteristic and variable, often showing signs of atrial enlargement and right ventricular hypertrophy (RVH). Occasionally, left axis deviation may be noted, though RV forces are usually prominent.

• Chest Radiography (CXR): May show cardiomegaly and increased pulmonary vascular markings or pulmonary edema. The upper mediastinum may appear narrow due to thymic absence, commonly seen with DiGeorge syndrome.

• Cardiac Catheterization and Angiography: While once primary, these are now largely replaced by Cardiac Magnetic Resonance Imaging (CMRI) and Cardiac CT for assessing anatomy, especially coronary arteries and arch defects. Catheterization can still be used for diagnostic and therapeutic purposes in some children.

7. Management

Management of DORV is complex due to its variable anatomy and physiology, ranging from straightforward to complex biventricular and single ventricle strategies.

For Taussig-Bing anomaly, the primary surgical approach is:

• Some of these patients may require an emergent septostomy to ensure sufficient mixing - similar to the dTGA patients.

• Arterial Switch Operation (ASO) with VSD closure: This is considered the standard treatment. The VSD closure reroutes the pulmonary trunk to the LV.

• Timing of Surgery: These operations should ideally be carried out by 3 to 4 months of age or sooner due to the rapid development of pulmonary vascular obstructive disease in this subtype.

• Aortic Arch Reconstruction: Ascending aorta and arch reconstruction may be necessary in about 50% of cases. In such complex cases, a staged repair with initial arch repair and pulmonary artery banding (PAB) is an alternative to complete primary repair.

• Pre-operative measures: If heart failure develops, vigorous anticongestive measures with digitalis and diuretics should be pursued. PGE1 infusion is necessary for newborns with associated severe PS, pulmonary atresia, interrupted aortic arch, or coarctation.

• Post-operative follow-up: Regular follow-up is necessary to detect complications like stenosis of the PA or aorta in supravalvular regions, coronary artery obstruction, ventricular dysfunction, arrhythmias, and/or semilunar valve regurgitation.

• The Rastelli procedure is sometimes needed for complex forms of Double Outlet Right Ventricle (DORV), including specific presentations within the DORV-TGA / Taussig-Bing Anomaly spectrum. While the Arterial Switch Operation (ASO) with VSD closure is considered the standard treatment for Taussig-Bing anomaly, the choice of surgical approach for DORV is complex and depends on the specific anatomy and associated lesions.

• The Rastelli operation typically involves:

  • Baffling of the ventricular septum to direct the left ventricular (LV) outflow through the VSD into the aorta, which arises from the right ventricle (RV). This essentially creates an intraventricular tunnel between the VSD and the aortic valve.

  • Closure of the proximal pulmonary trunk or native right ventricular outflow tract (RVOT).

  • Placement of a valved conduit (such as an aortic or pulmonary homograft, or a heterograft) between the right ventricle and the distal pulmonary artery. This conduit provides pulmonary blood flow.

• Timing of Intervention

  • For TGA with LVOTO, the corrective surgery is typically performed within the first year of life.

  • If performed in early life, the RV-PA conduit will likely need to be changed as the patient grows.

  • Other procedures like the REV (Réparation à l'Etage Ventriculaire) procedure and Nikaidoh procedure have become other alternatives to Rastelli due to potential long-term issues, particularly for TGA with VSD and severe PS. The REV procedure aims to avoid artificial material, while Nikaidoh involves aortic root translocation.

References:

• Breatnach C, Floh AA. Transposition of the Great Arteries: Surgical Procedures and Alternatives. In: Dipchand AI, Barron DJ, Floh AA, editors. Manual of Cardiac Care in Children. Cham, Switzerland: Springer Nature Switzerland AG; 2024. 

• Bradley TJ, Karamlou T, Kulik A, et al. Determinants of repair type, reintervention, and mortality in 393 children with double-outlet right ventricle. J Thorac Cardiovasc Surg. 2007;134:967–73. 

• Rudolph AM. Congenital Diseases of the Heart: Clinical-Physiological Considerations. 3rd ed. Oxford: Wiley-Blackwell; 2009. 

• Horer J, Schreiber C, Dworak E, et al. Long-term results after the Rastelli repair for transposition of the great arteries. Ann Thorac Surg. 2007;83:2169–75. 

• Barron DJ. Congenitally Corrected Transposition: Surgical Management. In: Dipchand AI, Barron DJ, Floh AA, editors. Manual of Cardiac Care in Children. Cham, Switzerland: Springer Nature Switzerland AG; 2024. 

• Lintermans JP. 2D echocardiography in infants and children. Dordrecht, The Netherlands: Martinus Nijhoff Publishers; 

• Dipchand AI, Barron DJ, Floh AA, editors. Manual of Cardiac Care in Children. Cham, Switzerland: Springer Nature Switzerland AG; 2024.

• Park IS, editor. An Illustrated Guide to Congenital Heart Disease: From Diagnosis to Treatment – From Fetus to Adult. Singapore: Springer Nature Singapore Pte Ltd.; 2019. 

• Batisse A, Fermont L, Lévy M. Cardiologie pédiatrique pratique: Du fœtus à l’adulte. 4th ed. Rueil-Malmaison Cedex, France: DOIN EDITEURS Wolters Kluwer France; 2013. 

• Lue HC, editor. Pediatric Cardiology Updates. Tokyo: Springer Japan KK; 1997. 

• Alboliras ET, Hijazi ZM, Lopez L, Hagler DJ, editors. Visual Guide to Neonatal Cardiology. Wiley; 2018.

• https://pmc.ncbi.nlm.nih.gov/articles/PMC2801930/ 

Echocardiographic Example of DORV-TGA

Double outlet right ventricle with subpulmonary ventricular septal delect, transposition type with large ventricular septal defect. Moderate unrestrictive secundum atrial septal delect (ASD). Mild aorlic arch hypoplasia (tubular). 

Here, as we sweep, we can appreciate the bicaval view, then the pulmonary artery arising from above the subpulmonary VSD and finally the Aorta arising from the RV.

Colour allows to visualize the flow entering both outflow tracts. There is no sign of acceleration or obstruction in the outflow tract to the Aorta, or to the PA arising over the subpulmonary VSD. The PA is of larger caliber than the Aorta. The PV annulus is larger than the Aortic annulus. 

Subcostal sweeps to assess ASD, VSD, relationship of ventricles to the great vessels.  

Subpulmonary VSD visualization. 

Apical view to visualize the extent of the subpulmonary ventricular septal defect.  

Subpulmonary VSD with colour flow. There is an overriding pulmonary artery. The VSD is large. 

Coronary flow visualization.

2D and colour to visualize the coronary artery arising from the aortic root. 

Measurements of the VSD diameter