Abstract 4561: Larger Ventricular Volumes in Infants with Single Ventricle Correlate with Increased Total Pressure Gradient Measured by Cardiac MRI
Early diastolic intra-ventricular pressure gradients (IVPGs) contribute to early filling and are an index of elastic recoil. They have not been reported in children but larger values in adults are associated with lower ESV and increased ventricular suction. We examined the feasibility of measuring pressure gradients in infants with single ventricle physiology and hypothesize that filling pressure gradients will provide a quantitative measure of diastolic function. Nine infants, median age 4 months, underwent echocardiography and cardiac MRI prior to bidirectional Glenn shunt to evaluate ventricular volumes and function. Phase contrast blood velocity imaging was used to evaluate the intra-ventricular and total atrial-ventricular pressure gradients by direct application of the Euler equation. Increased median indexed ventricular volumes (EDV = 90 ml/m2, ESV 45 ml/m2) were positively related to peak total pressure gradient (EDV: r = 0.85, p=0.004 and ESV: r = 0.77, p=0.015). There was a positive correlation between peak IVPG and EDV (r = 0.85, p=0.004), but not with ESV (r = 0.41, p=0.27). Echocardiographic measures of diastolic function did not correlate to the total pressure gradient. We have shown that increased total pressure gradients are associated with larger indexed volumes (EDV & ESV) in the single ventricle but that IVPGs are not correlated to ESV. These findings suggest that infants with a functional single ventricle rely on increased total pressure gradients for early diastolic filling, and may reflect a compensatory increase in atrial contribution to filling not associated with increased suction.