A modified Glenn shunt reduces venous congestion during acute right ventricular failure due to pulmonary banding: a randomized experimental study

Abstract

Objectives: Right ventricular failure after left ventricular assist device implantation is a serious complication with high rates of mortality and morbidity. It has been demonstrated in experimental settings that volume exclusion of the right ventricle with a modified Glenn shunt can improve haemodynamics during ischaemic right ventricular failure. However, the concept of a modified Glenn shunt is dependent on a normal pulmonary vascular resistance, which can limit its use in some patients. The aim of this study was to explore the effects of volume exclusion with a modified Glenn shunt during right ventricular failure due to pulmonary banding, and to study the alterations in genetic expression in the right ventricle due to pressure and volume overload.

Methods: Experimental right ventricular failure was induced in pigs (n = 11) through 2 h of pulmonary banding. The pigs were randomized to either treatment with a modified Glenn shunt and pulmonary banding (n = 6) or solely pulmonary banding (n = 5) as a control group. Haemodynamic measurements, blood samples and right ventricular biopsies for genetic analysis were sampled at baseline, at right ventricular failure (i.e. 2 h of pulmonary banding) and 1 h post-right ventricular failure in both groups.

Results: Right atrial pressure increased from 10 mmHg (9.0-12) to 18 mmHg (16-22) (P < 0.01) and the right ventricular pressure from 31 mmHg (26-35) to 57 mmHg (49-61) (P < 0.01) after pulmonary banding. Subsequent treatment with the modified Glenn shunt resulted in a decrease in right atrial pressure to 13 mmHg (11-14) (P = 0.03). In the control group, right atrial pressure was unchanged at 19 mmHg (16-20) (P = 0.18). At right heart failure, there was an up-regulation of genes associated with heart failure, inflammation, angiogenesis, negative regulation of cell death and proliferation.

Conclusions: Volume exclusion with a modified Glenn shunt during right ventricular failure reduced venous congestion compared with the control group. The state of right heart failure was verified through genetic expressional changes.

Keywords: Assisted circulation; Bidirectional Glenn shunt; Microarray analysis; Right-sided heart failure.

Figure 1:

(A) Modified Glenn shunt with a vascular clamp on the SVC proximal to the shunt, diverting the venous return from the upper body directly to the PA. The PA is constricted proximal to the modified Glenn shunt. (B) Experimental protocol and time points of measurements.

Figure 2:

Median right atrial pressure with 95% confidence interval throughout the experiment (n = 11).

Figure 3:

Median systolic and diastolic RV pressure with 95% confidence interval throughout the experiment (n = 11).