Double Outlet Right Ventricle

Definition & Morphology

Double Outlet Right Ventricle (DORV) represents a heterogeneous group of congenital cardiac anomalies.

Feature	Description
Core Definition	Both great arteries (aorta and pulmonary artery) arise predominantly (>50%) from the morphologically right ventricle (RV).
LV Outlet	Left ventricle (LV) lacks direct arterial connection. Ventricular septal defect (VSD) serves as sole LV outlet.
Valvar Continuity	Mitral-semilunar valve discontinuity present. Separated by smooth muscular conus.
Infundibulum	Bilateral coni (muscular infundibulums) typically support both semilunar valves.

Categorized primarily by VSD location relative to great arteries, dictating postnatal hemodynamics.

VSD Location	Incidence	Hemodynamics & Pathophysiology
Subaortic	55-70%	Aorta closest to VSD. Physiology depends on Pulmonary Stenosis (PS). - Without PS: Behaves like large VSD. L-to-R shunt. Pulmonary overcirculation. - With PS: Behaves like Tetralogy of Fallot (TOF). R-to-L shunt. Cyanosis.
Subpulmonary	Minority	Also termed Taussig-Bing anomaly. Pulmonary artery closest to VSD. - Behaves like Transposition of Great Arteries (d-TGA) with VSD. - Highly associated with aortic arch obstruction/coarctation.
Doubly Committed	~10%	Defect adjacent to both aortic and pulmonary valves. Absent/deficient outlet septum.
Non-committed	~10%	Remote from semilunar valves. Involves trabecular/inlet septum. Complex intracardiac streaming.

Manifestations hinge on VSD location and outflow tract obstruction severity.

Cyanosis:
- Severe in TOF-variant (due to PS restricting pulmonary flow).
- Severe in Taussig-Bing variant (transposition physiology).
Congestive Heart Failure (CHF):
- Presents with tachypnea, hepatomegaly, poor weight gain.
- Prominent in Subaortic VSD (without PS) and Taussig-Bing due to massive pulmonary overcirculation.
Auscultation:
- Hyperactive precordium.
- Ejection systolic murmur (pulmonary stenosis or relative PS from high volume).
- Holosystolic murmur (restrictive VSD).
- Apical mid-diastolic rumble (relative mitral stenosis from massive pulmonary venous return).

Modality	Key Findings
Echocardiography	Diagnostic Gold Standard. Confirms RV origin of both great arteries (>50% override). Delineates VSD location/size, great vessel orientation, outflow tract obstruction.
ECG	Right axis deviation. Right, left, or biventricular hypertrophy.
Chest X-Ray	- Without PS / Taussig-Bing: Cardiomegaly, increased pulmonary vascular markings (plethora). - With PS (TOF-type): Normal heart size, decreased pulmonary markings.
Cardiac CT / MRI	Defines complex spatial relationships, coronary anatomy, collateral vessels, exact VSD-arterial root routing.
Cardiac Catheterization	Assesses pulmonary vascular resistance (late presentation), coronary anomalies, intracardiac pressures.

Prostaglandin E1 (PGE1): Initiated for ductal-dependent pulmonary flow (severe PS/atresia) or systemic flow (Taussig-Bing with arch interruption/coarctation).
Balloon Atrial Septostomy (BAS): Indicated for severe cyanosis/inadequate mixing (specifically Taussig-Bing variant).
Heart Failure Therapy: Diuretics, inotropes, optimized nutrition for pulmonary overcirculation.
Pulmonary Artery (PA) Banding: Palliative. Limits pulmonary blood flow, controls CHF, protects pulmonary vascular bed prior to delayed definitive repair.

Surgical strategy dictated by VSD location, distance to great vessels, and outflow obstruction.

Variant	Preferred Surgical Approach
Subaortic VSD (No PS)	Intracardiac Baffle (Tunnel). Patches VSD to aorta, directing LV blood unobstructed to systemic circulation.
Subaortic VSD + PS	Intracardiac Baffle + RVOT Reconstruction. Relieves PS. If anatomy complex, requires Rastelli Procedure (VSD baffle to aorta + RV-to-PA extracardiac conduit).
Subpulmonary VSD (Taussig-Bing)	Arterial Switch Operation (ASO) + VSD Closure. Great vessels translocated. VSD baffled to neo-aorta. Arch repair performed concurrently if coarctation present.
Non-committed / Remote VSD	Highly complex. Biventricular repair often impossible. Managed via Single Ventricle Pathway leading to total cavopulmonary connection (Fontan procedure).