Double-outlet right ventricle (DORV) refers to a spectrum of cardiac lesions unified by an abnormal ventriculoarterial connection.¹ DORV is most commonly defined as a condition in which more than 50% of both the aortic root and the pulmonary artery arise from the ventricle with right morphological features.^2–5 A ventricular septal defect (VSD) is usually, but not always, present.⁵

DORV was first described in 1703.⁶ It was considered to be one type of transposition of the great arteries (TGA). In 1898, Vierordt referred to DORV as a partial transposition because only the aorta was actually transposed as the pulmonary artery originates appropriately from the right ventricle.⁷

In 1949, Taussig and Bing⁸ described a patient with “complete transposition of the aorta and levoposition of the pulmonary artery.” They described the first reported case in which both great arteries arose from the right ventricle, but the VSD was related to the pulmonary artery and not the aorta, as had been the case in all previous reports.⁵ In 1952, Braun et al⁹ described a case in which “the right ventricle serves as a double outlet ventricle.” They classified it as a partial transposition of the Fallot type.

The term “double-outlet right ventricle” was first used by Witham¹⁰ in 1957. He considered it to be a partial transposition complex in which both great arteries arose from the right ventricle. He divided his cases of DORV into two groups—the Fallot type and the Eisenmenger type—depending on whether pulmonary stenosis was present or absent.⁷

A classification system for DORV was first developed by Neufeld et al11,12 in 1961. They separated cases into those with and those without pulmonary stenosis and included an additional category for those with “other intracardiac malformations.” They later subcategorized the group without pulmonary stenosis on the basis of the position of the VSD in relation to the crista supraventricularis and the great arteries.¹³

In 1972, Lev et al¹⁴ classified DORV on the basis of the relationship of the VSD to the two great arteries, including subaortic, subpulmonary, doubly committed (involving both great vessels), or noncommitted (distant from either great artery). They advocated expanding the definition of DORV to include cases in which only two cusps and part of a third cusp of both semilunar valves originate from the right ventricle. Additionally, they considered the Taussig-Bing type of DORV as a spectrum ranging from cases in which both great arteries arise wholly from the right ventricle to those with pulmonary-mitral continuity, as in complete transposition.

In 1982, Van Praagh developed the most widely accepted classification of DORV, which included the following2,5,15–21:

• DORV with a subaortic VSD

• DORV with a subpulmonary VSD

• DORV with a doubly committed (both subaortic and subpulmonic) VSD

• DORV with a remote VSD (noncommitted) (Fig. 17–1)

Four types of great artery relationships at the level of the semilunar valves have been described in DORV¹⁹:

In 1978, Sridaromont et al²⁰ evaluated angiographically 72 patients with proven DORV to determine the location of a VSD when it was associated with various great artery relationships. They identified 16 possible combinations (Fig. 17–2).

Subaortic VSDs were the most common finding, occurring in 68% of cases. The most common combination was a subaortic VSD with side-by-side great vessels. This was seen in 46% of patients. A subaortic VSD with dextromalposition of the great vessels (right anterior aorta) was the next most common combination, occurring in 16% of patients. Subpulmonary VSDs were identified in 22% of cases, usually with dextromalposition of the great vessels (10%).

The combination of a subpulmonary VSD with side-by-side great vessels was found in 8% of patients. This type of DORV is commonly considered the classic Taussig-Bing heart (Fig. 17–3).¹⁴ Pulmonary stenosis is not associated with this particular anomaly; therefore, the pulmonary artery is usually dilated. Anatomically, a subpulmonary VSD is usually located in a more anterior position than is a subaortic VSD.

Doubly committed VSDs were found in only 3% of patients. All patients had side-by-side great vessels. In this type of DORV, the VSD is usually in a superior position and closely related to both semilunar valves. It is often large.

Remote or noncommitted VSDs were identified in 7% of patients in this series. Similar to the doubly committed VSD, all were associated with side-by-side great vessels. The most common form recognized as a remote VSD is a complete atrioventricular canal defect with DORV.⁷ This type can, however, be located in the anterior, middle, or posterior muscular septum.²² DORV with a remote VSD is often associated with the heterotaxy syndromes. In a more recent study, Bradley et al²¹ reviewed 393 cases of DORV. They also reported DORV with a subaortic VSD as being the most common form, occurring in 47% of cases. DORV with a noncommitted VSD was found in 26%, DORV with a subpulmonic VSD was found in 23%, and DORV with a doubly committed VSD was diagnosed in 4%.

DORV with an intact ventricular septum has also been reported.20,23–26 It is, however, exceedingly rare. This type of DORV is usually associated with hypoplasia of the left ventricle and with anomalies of the mitral valve.

Although the Van Praagh system is still considered by many to be the traditional classification of DORV, many authors thought that it was not ideal because it is based solely on the anatomical relationship between the VSD and the great arteries and does not consider the surgical approach. In 2000, the Society of Thoracic Surgeons and the European Association of Cardiothoracic Surgery adopted four types of DORV on the basis of clinical presentation and treatment²⁷:

Embryology

Historically, DORV was thought to result from a failure of the normal spiraling of the aorta and pulmonary trunk, resulting in abnormal positioning. However, more recent research confirms that the primitive right ventricle is in fact a DORV, containing the conotruncus. If migration of the aortic side of the conotruncus toward the mitral valve is incomplete, the DORV anatomy persists.³⁸ Another refinement of accepted embryology suggests that DOLV is actually caused by the misalignment and arrest of the ventricular septum.³⁹

Regardless of the precise embryological events, it is correct to assume that DORV and DOLV represent a spectrum of complex defects that result from a failure of the normal sequence of events.

Occurrence Rate

DORV is considered a rare congenital malformation, occurring in approximately 0.033 to 0.09 per 1000 live births.40–43 The frequency among abortuses and stillborn infants is reported to be 2.4%.⁴⁴ There does not appear to be an ethnic or a sex predilection in DORV.

Related posts:

First-Trimester Fetal Echocardiography Congenital Cardiac Masses Complete and Congenitally Corrected Transposition of the Great Arteries Atrial Septal Defects Ventricular Septal Defects Scanning: Indications and Technique

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