The New Concept of Univentricular Heart

Abstract

The concept of univentricular heart moved from hearts with only one ventricle connected with atria [double inlet ventricle or absent atrioventricular (AV) connection] to hearts not amenable to biventricular repair, namely hearts with two ventricles unable to sustain separately pulmonary and systemic circulations in sequence. In the latter definition, even hearts with one hypoplastic ventricle are considered “functional” univentricular hearts. They include pulmonary/aortic atresia or severe stenosis with hypoplastic ventricle, and rare conditions like huge intramural cardiac tumors and Ebstein anomaly with extreme atrialization of right ventricular cavity. In this setting, the surgical repair is univentricular with “Fontan” operation, bypassing the ventricular mass. In other words, functionally univentricular heart is a condition in which, after surgery, only one ventricle sustain systemic circulation. Univentricular hearts (double inlet or absent AV connection) almost invariably show two ventricular chambers, one main and one accessory, which lacks an inlet portion. The latter is located posteriorly when morphologically left and anteriorly when morphologically right. As far as double inlet left ventricle, this is usually associated with discordant ventriculo-arterial (VA) connection (transposition of the great arteries) and all the blood flow to the aorta, which takes origin from the hypoplastic anterior right ventricle, is ventricular septal defect (bulbo-ventricular foramen) dependent. If restrictive, an aortic arch obstruction may be present. Double inlet left ventricle may be rarely associated with VA concordance (Holmes heart). As far as double inlet right ventricle with posterior hypoplastic left ventricular cavity, ventriculo-arterial connection is usually of double outlet type; thus the term double inlet–outlet right ventricle may be coined. Absent right or left AV connection may develop in the setting of both d- or l-loop, whatever the situs. In this condition, the contra-lateral patent AV valve may be either mitral or tricuspid in terms of morphology and the underlying ventricle (main chamber) either morphologically left or right. Establishing the loop, whatever right or left (also called right or left ventricular topology), is a fundamental step in the segmental-sequential analysis of congenital heart disease.

A restrictive ventilatory pattern is common in patients with univentricular heart after Fontan palliation and associated with a reduced exercise capacity and quality of life

“…1 Different surgical variants have been proposed since its first introduction: atriopulmonary connection (APC), atrioventricular connection (AVC), and total cavopulmonary connection (TCPC). 4 However, this palliation has intrinsic limitations 5 and the circumvention and management of long-term complications is still a major topic in the care of these patients. 3 This approach is now performed in all functional univentricular hearts (UVH) unable to sustain the systemic and pulmonary circulation separately.…”

Double inlet left ventricle–ventriculoarterial discordance without surgical treatment

“…In patients with clinically significant subaortic obstruction, Damus-Kaye-Stansel surgery and BVF distension are performed. [1][2][3][4]7 The present patient did not have a BVF obstruction, significant insufficiency of AV valves, subaortic stenosis or aortic coarctation, which would have worsened the prognosis. The patient's main ventricle had the morphology of a left ventricle, and the ventricular topology was L-loop.…”

“…In the majority of cases, there is an association between levocardia, situs solitus atria and abdominal organ. [1][2][3] The condition of double inlet left ventricle (DILV), in which the main ventricle is located in the left ventricle anatomy, accounts for approximately 70-80% of cases. The blood is completely merged in the main ventricle inside the heart and the systemic oxygen saturation is determined by pulmonary blood flow.…”

Prenatal diagnosis of functionally univentricular heart, associations and perinatal outcomes

“…Functionally univentricular hearts (UVH) have in common, that postnatally, either the pulmonary or systemic circulation cannot be supported independently; thus, a biventricular circulation is not possible. The majority usually possesses two ventricles, one large and one small, the true UVH is rare …”

“…The majority usually possesses two ventricles, one large and one small, the true UVH is rare. [1][2][3] Despite improvement in perinatal management the last three decades, mortality is still observed in patients with functionally UVH. [4][5][6] The 15-year survival rate for hypoplastic left heart syndrome (HLHS) and variants is reported to be 77% after 'Giessen-Hybrid' approach in a recent single centre analysis and 60% in a large study using the Norwood procedure.…”