Pericardial constriction and myocardial restriction in pediatric Mulibrey nanism – a complex disease with diastolic dysfunction

ABSTRACT 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 and results 23 MUL and 23 individually sex and age matched healthy controls were prospectively assessed in a cross-sectional study with echocardiography. Clinical signs of heart failure were present in 7 MUL, with severe congestive heart failure in 2. Significant diastolic dysfunction mainly related with constriction was found in MUL 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 controls. Longitudinal diastolic myocardial velocities were similar to controls suggesting absence of significant myocardial restriction. Right ventricular free wall longitudinal systolic strain and bilateral longitudinal myocardial systolic velocities were decreased in MUL indicating mild biventricular systolic dysfunction. Myocardial motion abnormalities and persistent congestive heart failure were common (3 out of 6) in MUL with history of pericardiectomy. Cardiac dimension were similar between MUL and controls when adjusting for body size, except for smaller biventricular volumes. Conclusion 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 pericardiectomy decision making in MUL disease. Myocardial abnormalities were prevalent among MUL with pericardiectomy performed and consistent with progression of myocardial disease in a significant proportion of patients.