Double-inlet single left ventricle: Echocardiographic anatomy with emphasis on the morphology of the atrioventricular valves and ventricular septal defect

Abstract

The echocardiographic anatomy of double-inlet single left ventricle was studied in 57 patients, aged 1 day to 27 years (mean 6 years); the variables examined included morphology, size and function of the atrioventricular (AV) valves and ventricular septal defect and their relation to pulmonary stenosis, aortic stenosis and aortic arch obstruction. The visceroatrial situs was solitus and the heart was in the left side of the chest in all 57 patients. A d-loop ventricle was present in 21 patients and an l-loop ventricle in 36. The great arteries were normally related (Holmes heart) in 8 patients and transposed in 49. In all hearts, the right AV valve was anterior to the left AV valve. In 53 patients, the tricuspid valve (right valve in d-loop and left valve in l-loop) was closer to and had attachments on the septum. The tricuspid valve straddled the outflow chamber in eight patients. No significant difference was noted in the mean AV valve diameter when comparing mitral and tricuspid valves within the same group or between the groups with a d- or l-loop ventricle. The right AV valve diameter had a significant direct correlation with the aortic valve diameter and the size of the ventricular septal defect regardless of ventricular loop. Both AV valves were functionally normal in 34 patients. Among patients with AV valve dysfunction, the tricuspid valve tended to be stenotic in patients with an l-loop ventricle and regurgitant in patients with a d-loop ventricle. Mitral valve dysfunction was uncommon. The ventricular septal defect (46 patients) was separated from the semilunar valves in 24 patients (muscular defect) and adjacent to the anterior semilunar valve as a result of hypoplasia or malalignment, or both, of the infundibular septum (subaortic defect) in 19 patients. Multiple defects were present in three patients. The defect was unrestrictive in 26 patients, restrictive in 23 and could not be evaluated in 8. Pulmonary artery banding had been performed in 8 of the 26 patients with an unrestrictive defect and in 10 of the 23 patients with a restrictive defect. Only 4 of 19 subaortic defects compared with 16 of 24 muscular defects were restrictive. The size of the defect was significantly correlated with the measured pressure gradient. Among patients with transposition, only 2 of 13 with pulmonary stenosis had a restrictive ventricular septal defect compared with 15 of 30 without pulmonary stenosis. In patients with transposition, the defect size was significantly smaller when coarctation was present.

Univentricular Heart

“…34 A common AV valve with a 5-leaflet configuration is commonly found in univentricular hearts with atrial isomerism and is best viewed from parasternal short axis and apical 4-chamber views. 2,7,33 In DILV, the rudimentary right ventricular chamber may be readily identified and localized, often in the parasternal short-axis view. In the most common subtype (type III), the rudimentary right ventricle gives rise to the aorta and well-formed left ventricle to the pulmonary artery.…”

“…In DILV, there are usually 2 separate patent AV valves, but either may be imperforate, stenotic, or regurgitant. 7,33 Either valve may straddle the bulboventricular foramen. 34 A common AV valve with a 5-leaflet configuration is commonly found in univentricular hearts with atrial isomerism and is best viewed from parasternal short axis and apical 4-chamber views.…”

“…Left ventricular morphology may be inferred when the aorta emanates from an anterosuperior rudimentary chamber. 7,33 A univentricular heart with a well-formed right ventricle can often be surmised to exist on the basis of typical right ventricular morphological characteristics.…”

Can we describe structure as well as function when accounting for the arrangement of the ventricular mass?

“…Thus, hearts with double inlet left ventricle are said to possess a "single left ventricle". 25 In reality, in such hearts, all the morphological evidence points to the second chamber being a rudimentary and incomplete right ventricle, as is the second chamber in hearts with tricuspid atresia. There is no evidence of which we are aware to show that the chamber is simply an infundibulum.…”

Transcatheter Decompression of the Left Atrium in an Adolescent with a Double Inlet Left Ventricle, Severe Parachute Mitral Valve Stenosis and Pulmonary Hypertension

“…Multiple morphological variants can be associated, but mitral valve dysfunction is uncommon [1]. The prognosis of UVH is usually poor without early surgical interventions; a median survival of 14 years was reported [2].…”