Numerical, hydraulic, and hemolytic evaluation of an intravascular axial flow blood pump to mechanically support Fontan patients.

Currently available mechanical circulatory support systems are limited for adolescent and adult patients with a Fontan physiology. To address this growing need, we are developing a collapsible, percutaneously-inserted, axial flow blood pump to support the cavopulmonary circulation in Fontan patients. During the first phase of development, the design and experimental evaluation of an axial flow blood pump was performed. We completed numerical modeling of the pump using computational fluid dynamics analysis, hydraulic testing of a plastic pump prototype, and blood bag experiments (n=7) to measure the levels of hemolysis produced by the pump. Statistical analyses using regression were performed. The prototype with a 4-bladed impeller generated a pressure rise of 2-30 mmHg with a flow rate of 0.5-4 L/min for 3000-6000 RPM. A comparison of the experimental performance data to the numerical predictions demonstrated an excellent agreement with a maximum deviation being less than 6%. A linear increase in the plasma-free hemoglobin (pfHb) levels during the 6-h experiments was found, as desired. The maximum pfHb level was measured to be 21 mg/dL, and the average normalized index of hemolysis was determined to be 0.0097 g/100 L for all experiments. The hydraulic performance of the prototype and level of hemolysis are indicative of significant progress in the design of this blood pump. These results support the continued development of this intravascular pump as a bridge-to-transplant, bridge-to-recovery, bridge-to-hemodynamic stability, or bridge-to-surgical reconstruction for Fontan patients.

Congenital complete heart block: fetal management protocol, review of the literature, and report of the smallest successful pacemaker implantation.

Fetuses with complete heart block have an increased mortality with most deaths occurring in utero or during infancy. The cardiac evaluation of these fetuses is difficult since the ventricular rate is low and the heart is dilated. We have implemented a strategy that includes the biophysical profile, which assesses fetal well-being, in combination with the cardiovascular profile that assesses cardiac function and the circulation. We present two cases of fetal complete heart block in which early delivery was recommended due to worsening cardiovascular profile scores. Biophysical profile scores were normal. Both babies were successfully treated, despite having risk factors that predicted poor outcomes. We hypothesize that our management protocol initiated intervention before fetal compromise, hydrops, and myocardial damage occurred. We recommend an evaluation of heart function in addition to an assessment of fetal well-being in fetuses with complete heart block. Early delivery should be considered if there is evidence of distress and/or deteriorating cardiac function.