Hemodynamic Effects of Partial Right Ventricular Support in the Acute Vs the Chronic Pressure Overloaded Right Ventricle

PurposeTemporary right ventricular (RV) support for the acute pressure overloaded RV after heart transplantation or acute lung edema is well described. However, patients with a chronic pressure-overloaded RV might also benefit from this support. We wanted to assess the hemodynamic effects of RV support in the acute vs the chronic pressure overloaded RV.MethodsThe pulmonary artery was banded in 16 sheep. In 8 sheep we immediately [‘Acute’] implanted a CircuLite® Synergy® micro-pump draining blood from the right atrium to the pulmonary artery. In the second group, the same pump was implanted only 8 weeks after banding [‘Chronic’]. Hemodynamics were recorded before and after pump implantation.ResultsOnly in ‘Chronic’, initiation of the pump resulted in a significant increase of left atrial pressure (4.9±2.0mmHg vs 7.4±3.0 mmHg, p<0.01) and a significant decrease of RV end systolic pressure (41±7mmHg vs 31±9 mmHg, p<0.05). The pump generated flows of 1.40±0.47L/min in ‘Acute’ and 2.81±0.12L/min in ‘Chronic’(p<0.0001), both at 22 kRPM. There was no difference in total cardiac output between ‘Acute’ and ‘Chronic’. However, the contribution of the RV in generating the total cardiac output was significantly lower in ‘Chronic’ (19±12vs59±8%, p<0,00001). Pressure-volume loop analysis showed that in supported ‘Chronic’ stroke volume, ejection fraction and end systolic pressure were significantly lower (15.4±5.8vs25.4±4.4ml,p<0.01; 17±6vs25±4%,p<0.05 and 27.7±7.4vs43.1±12.0mmHg,p<0.05, respectively), compared to the supported ‘Acute’. The % of stroke work performed by the supported RV compared to the unsupported RV was significantly lower in ‘Chronic’ than in ‘Acute’ (13±11% vs 62±9%, p<0.000001).ConclusionSupporting the pressure overloaded RV optimizes hemodynamics towards the same levels in ‘Acute’ vs ‘Chronic’. However, the contribution of the RV to the generation of the total CO is significantly lower in ‘Chronic’. Therefore, at our opinion, the failing RV might benefit even more from mechanical support in case of chronic pressure overload. PurposeTemporary right ventricular (RV) support for the acute pressure overloaded RV after heart transplantation or acute lung edema is well described. However, patients with a chronic pressure-overloaded RV might also benefit from this support. We wanted to assess the hemodynamic effects of RV support in the acute vs the chronic pressure overloaded RV. Temporary right ventricular (RV) support for the acute pressure overloaded RV after heart transplantation or acute lung edema is well described. However, patients with a chronic pressure-overloaded RV might also benefit from this support. We wanted to assess the hemodynamic effects of RV support in the acute vs the chronic pressure overloaded RV. MethodsThe pulmonary artery was banded in 16 sheep. In 8 sheep we immediately [‘Acute’] implanted a CircuLite® Synergy® micro-pump draining blood from the right atrium to the pulmonary artery. In the second group, the same pump was implanted only 8 weeks after banding [‘Chronic’]. Hemodynamics were recorded before and after pump implantation. The pulmonary artery was banded in 16 sheep. In 8 sheep we immediately [‘Acute’] implanted a CircuLite® Synergy® micro-pump draining blood from the right atrium to the pulmonary artery. In the second group, the same pump was implanted only 8 weeks after banding [‘Chronic’]. Hemodynamics were recorded before and after pump implantation. ResultsOnly in ‘Chronic’, initiation of the pump resulted in a significant increase of left atrial pressure (4.9±2.0mmHg vs 7.4±3.0 mmHg, p<0.01) and a significant decrease of RV end systolic pressure (41±7mmHg vs 31±9 mmHg, p<0.05). The pump generated flows of 1.40±0.47L/min in ‘Acute’ and 2.81±0.12L/min in ‘Chronic’(p<0.0001), both at 22 kRPM. There was no difference in total cardiac output between ‘Acute’ and ‘Chronic’. However, the contribution of the RV in generating the total cardiac output was significantly lower in ‘Chronic’ (19±12vs59±8%, p<0,00001). Pressure-volume loop analysis showed that in supported ‘Chronic’ stroke volume, ejection fraction and end systolic pressure were significantly lower (15.4±5.8vs25.4±4.4ml,p<0.01; 17±6vs25±4%,p<0.05 and 27.7±7.4vs43.1±12.0mmHg,p<0.05, respectively), compared to the supported ‘Acute’. The % of stroke work performed by the supported RV compared to the unsupported RV was significantly lower in ‘Chronic’ than in ‘Acute’ (13±11% vs 62±9%, p<0.000001). Only in ‘Chronic’, initiation of the pump resulted in a significant increase of left atrial pressure (4.9±2.0mmHg vs 7.4±3.0 mmHg, p<0.01) and a significant decrease of RV end systolic pressure (41±7mmHg vs 31±9 mmHg, p<0.05). The pump generated flows of 1.40±0.47L/min in ‘Acute’ and 2.81±0.12L/min in ‘Chronic’(p<0.0001), both at 22 kRPM. There was no difference in total cardiac output between ‘Acute’ and ‘Chronic’. However, the contribution of the RV in generating the total cardiac output was significantly lower in ‘Chronic’ (19±12vs59±8%, p<0,00001). Pressure-volume loop analysis showed that in supported ‘Chronic’ stroke volume, ejection fraction and end systolic pressure were significantly lower (15.4±5.8vs25.4±4.4ml,p<0.01; 17±6vs25±4%,p<0.05 and 27.7±7.4vs43.1±12.0mmHg,p<0.05, respectively), compared to the supported ‘Acute’. The % of stroke work performed by the supported RV compared to the unsupported RV was significantly lower in ‘Chronic’ than in ‘Acute’ (13±11% vs 62±9%, p<0.000001). ConclusionSupporting the pressure overloaded RV optimizes hemodynamics towards the same levels in ‘Acute’ vs ‘Chronic’. However, the contribution of the RV to the generation of the total CO is significantly lower in ‘Chronic’. Therefore, at our opinion, the failing RV might benefit even more from mechanical support in case of chronic pressure overload. Supporting the pressure overloaded RV optimizes hemodynamics towards the same levels in ‘Acute’ vs ‘Chronic’. However, the contribution of the RV to the generation of the total CO is significantly lower in ‘Chronic’. Therefore, at our opinion, the failing RV might benefit even more from mechanical support in case of chronic pressure overload.