Pericardial Constriction and Myocardial Restriction in Pediatric Mulibrey Nanism: A Complex Disease With Diastolic Dysfunction.

Background: Mulibrey nanism (MUL) is a rare condition with profound growth delay. Congestive heart failure is a major determinant of prognosis. The aim was to delineate pericardial constriction and myocardial functional abnormalities in a pediatric MUL sample.

Methods: A total of 23 MUL patients and 23 individually sex- and age-matched healthy control subjects were prospectively assessed in a cross-sectional study with echocardiography.

Results: Clinical signs of heart failure were present in 7 MUL patients, with severe congestive heart failure in 2. Significant diastolic dysfunction, mainly related to constriction, was found in MUL patients without pericardiectomy (N = 18)-septal bounce, pronounced hepatic vein atrial reversal and right heart inflow-outflow variations, and decreased inferior vena cava collapse during respiration. The appearance of the pericardium was not different from that of control subjects. Longitudinal diastolic myocardial velocities were similar to those in control subjects, suggesting an absence of significant myocardial restriction. Right ventricular free wall longitudinal systolic strain and bilateral longitudinal myocardial systolic velocities were decreased in MUL patients, indicating mild biventricular systolic dysfunction. Myocardial motion abnormalities and persistent congestive heart failure were common (in 3 of 6) in MUL patients with a history of pericardiectomy. Cardiac dimensions were similar between MUL patients and control subjects when adjusting for body size, except for smaller biventricular volumes.

Conclusions: MUL disease presents with significant constriction-related diastolic dysfunction and mild bilateral systolic dysfunction. Constriction-restriction assessments during follow-up could be of benefit in decision-making regarding pericardiectomy in MUL disease. Myocardial abnormalities were prevalent among MUL patients who had undergone pericardiectomy and are consistent with progression of myocardial disease in a significant proportion of patients.