Volume Loading May Compromise Left Ventricular Filling in Patients with a Borderline Hypoplastic Left Ventricle.

Given the high prevalence of end-organ damage in the long term after the Fontan procedure, patients presenting with borderline hypoplastic left ventricle (LV) are increasingly directed towards biventricular circulation. We present the case of a patient with borderline LV who developed severe pulmonary hypertension shortly after biventricular repair. We initially thought it was purely caused by a hypoplastic LV; however, it was partly induced by a delayed/prolonged right ventricular (RV) contraction that compressed the interventricular septum and impaired left ventricular filling, which was exacerbated by volume loading during cardiac catheterization. Although the coexisting right bundle branch block (RBBB) might have contributed to the delayed RV contraction, volume depletion through aggressive diuresis shortened the RV contraction interval, resulting in improvement of interventricular crosstalk and the alleviation of symptoms related to pulmonary congestion, regardless of the presence of complete RBBB. Subsequently, our patient achieved favorable LV growth after 2 years of observation. While volume loading has been considered as an option to promote the growth of the hypoplastic LV, aggressive fluid management may offer an alternative for allowing sufficient time to achieve adequate ventricular growth in cases of non-compliant LV properties.