Effect of mechanical assistance of the systemic ventricle in single ventricle circulation with cavopulmonary connection

Abstract

Background Previous attempts to support the single ventricle circulation mechanically have suggested that a custom-built assist device is needed to push rather than pull through the pulmonary circulation. We hypothesized that using a conventional ventricular assist device, with or without conversion of a total cavopulmonary connection to a bidirectional Glenn cavopulmonary connection would allow assistance by pulling blood through the circuit and improve cardiac index (CI). Methods Cavopulmonary connections were established in each of five Yorkshire pigs (25kg) using ePTFE conduits in a “Y” configuration with appropriate clamping of limbs of the Y to achieve: total cavopulmonary Fontan connection (TCPC), SVC cavopulmonary connection (SVC Glenn) and IVC cavopulmonary connection (IVC Glenn). A common atrium had been established previously by balloon septostomy. Mechanical circulatory assistance of the single systemic ventricle was achieved using a centrifugal pump with common atrial inflow and proximal ascending aortic outflow. CI was calculated using an ultrasonic flow meter placed on the distal ascending aorta and compared between assisted and non-assisted circulation for 3 conditions: TCPC, SVC Glenn and IVC Glenn. Mean pulmonary artery pressure (PAP), common atrial pressure (LAP), arterial oxygen saturation (SAT), partial pressure of arterial oxygen (PO2) and oxygen delivery (DO2) were calculated. Results Unassisted SVC Glenn CI tended to be higher than TCPC or IVC Glenn (Figure 1). Significant augmentation of total CI was achieved with mechanical assistance for SVC Glenn (109% ± 24%, P =.04) and also with TCPC (130% ± 109%, P = .01). Assisted CI achieved at least mean baseline biventricular CI for all 3-support modes. Oxygen delivery was highest for assisted SVC Glenn 1786 ± 1307 ml/l/min and lowest with TCPC 1146 ± 386 ml/l/min, with a trend toward lower common atrial pressure and lower pulmonary artery pressure for SVC Glenn. Conclusions SVC bidirectional Glenn circulation may allow optimal augmentation of cardiac index and oxygen delivery in a failing single ventricle using a conventional pediatric ventricular assist device. Our model also suggests that the Fontan circulation itself can be supported with systemic ventricular assistance of the single ventricle.

Successful Bridge-to-Transplant of Functionally Univentricular Patients With a Modified Continuous-Flow Ventricular Assist Device

“…In all four patients in this series, the CPP was observed to decrease following VAD implantation, in conjunction with a decrease in the BNP. In an animal model studying the effect of mechanical assistance of the systemic ventricle in cavopulmonary connection with a centrifugal flow pump, Sinha et al demonstrated that improvement in cardiac index was accompanied by a decrease in the mean pulmonary artery pressure and left atrial pressure, suggesting that decompression of the systemic circulation was transmitted to the cavopulmonary circuit .…”

“…Based on the experimental work of Sinha et al, some degree of decreased oxygen saturation and arterial oxygen tension may be encountered in assisted patients with cavopulmonary connections. However, the augmentation of cardiac output by the VAD will offset the desaturation resulting in greater tissue oxygen delivery . Inadequate systemic oxygenation caused by impaired lung function can also be addressed by transitioning to ECMO.…”

An overview of mechanical circulatory support in single-ventricle patients

“…Conversely, there will also be an increased flow of deoxygenated blood through the inferior vena cava (IVC). The summation has been shown in an experimental model to lead to increased oxygen delivery (23). Additionally, in case reports, it leads to improved hemodynamics (24,25).…”

Mechanical Circulatory Support Devices for Pediatric Patients With Congenital Heart Disease

“…The pump has low priming volume of 32 mL and is able to support a wide range of patient sizes. The RotaFlow was approved by the FDA in 2000 and is approved for up to 6 h of LV support . The device has achieved the CE Mark in Europe for up to 30 days.…”

“…This pump is used frequently in ECMO circuits. Sinha et al have employed the RotaFlow in an animal model of SV physiology to compare MCS of the Fontan versus the bidirectional Glenn shunt. MCS in these configurations augmented improved cardiac index, but there was a decrease in the mean pulmonary arterial pressure and left atrial pressure.…”