Survival of Double Inlet Left Ventricle Patients Without Fontan Circulation: Intracardiac Anatomy and Hemodynamics, Functional Status and Quality of Life

Rationale: Patients with univentricular hearts are currently palliated with a sequence of operations known as the Fontan procedure. This results in an un-physiologic circulation with poor long-term survival. On the other hand there is a small, selected subgroup of patients with univentricular hearts of the double inlet left ventricle (DILV) type that survives up to old age without ever having undergone any Fontan procedure. Considering the relatively bleak data on long-term survival of DILV patients palliated with the Fontan procedure, it is highly relevant to investigate and determine factors that allow for a selection of unoperated patients to live to a comparatively high age without apparent major complaints. This might have an impact on how (and if, at all) certain univentricular patients will be selected for operation in the future. For some, a different surgical procedure, or even therapeutic nihilism might be a more viable alternative. The investigators hypothesize that favourable intracardiac streaming plays a role in making the unpalliated patients viable: certain intracardiac anatomical characteristics allow for favourable flow patterns, resulting in higher systemic oxygen saturations than expected by mixing pulmonary and systemic venous returns.

Objective: The primary objective of this study is to describe the intracardiac anatomy and hemodynamics of DILV patients without Fontan circulation using 4D MRI. Furthermore, the functional status and quality of life of these patients will be assessed and compared to a matched cohort of Fontan patients.

Study design: This will be an observational, cross-sectional study. The investigators aim to include all DILV patients without Fontan circulation known at the congenital heart disease referral centers in the Netherlands and Flanders. The Dutch patients will undergo one 4D MRI, a physical examination, cardiopulmonary exercise testing and have a blood sample taken at the University Medical Center Utrecht. The patients from the Flemish referral centers will undergo the same protocol at the University Medical Center Leuven. Furthermore, patients over the age of 18 will be asked to fill out a quality of life questionnaire.

Study population: Included will be patients over the age of 12 with the diagnosis double inlet left ventricle, which have not undergone the Fontan trajectory. For the 4D MRI, patients with an MRI non-compatible pacemaker in situ will be excluded.

Main study parameters/endpoints: This is primarily an explorative study aiming to describe the anatomy of unpalliated DILV hearts of patients without Fontan palliation. With 4D MRI, the hearts will be grouped according to the angular relationship of the two lines connecting the atrioventricular and the ventriculo-arterial valves. This angle can be divided into three categories: 1) parallel (i.e. 0°), 2) perpendicular (i.e. 90°) or 3) an in-between variant. Accordingly, flow patterns, ranging from linear to turbulent will be measured and correlated to the anatomical variants.