Abstract
BackgroundVenoarterial extracorporeal membrane oxygenation (VA ECMO) is widely used in the treatment of circulatory failure, but repeatedly, its negative effects on the left ventricle (LV) have been observed. The purpose of this study is to assess the influence of increasing extracorporeal blood flow (EBF) on LV performance during VA ECMO therapy of decompensated chronic heart failure.MethodsA porcine model of low-output chronic heart failure was developed by long-term fast cardiac pacing. Subsequently, under total anesthesia and artificial ventilation, VA ECMO was introduced to a total of five swine with profound signs of chronic cardiac decompensation. LV performance and organ specific parameters were recorded at different levels of EBF using a pulmonary artery catheter, a pressure–volume loop catheter positioned in the LV, and arterial flow probes on systemic arteries.ResultsTachycardia-induced cardiomyopathy led to decompensated chronic heart failure with mean cardiac output of 2.9 ± 0.4 L/min, severe LV dilation, and systemic hypoperfusion. By increasing the EBF from minimal flow to 5 L/min, we observed a gradual increase of LV peak pressure from 49 ± 15 to 73 ± 11 mmHg (P = 0.001) and an improvement in organ perfusion. On the other hand, cardiac performance parameters revealed higher demands put on LV function: LV end-diastolic pressure increased from 7 ± 2 to 15 ± 3 mmHg, end-diastolic volume increased from 189 ± 26 to 218 ± 30 mL, end-systolic volume increased from 139 ± 17 to 167 ± 15 mL (all P < 0.001), and stroke work increased from 1434 ± 941 to 1892 ± 1036 mmHg*mL (P < 0.05). LV ejection fraction and isovolumetric contractility index did not change significantly.ConclusionsIn decompensated chronic heart failure, excessive VA ECMO flow increases demands and has negative effects on the workload of LV. To protect the myocardium from harm, VA ECMO flow should be adjusted with respect to not only systemic perfusion, but also to LV parameters.
Highlights
Venoarterial extracorporeal membrane oxygenation (VA (Venoarterial) extracorporeal membrane oxygenation (ECMO)) is widely used in the treatment of circulatory failure, but repeatedly, its negative effects on the left ventricle (LV) have been observed
In the all animals in our study, fast ventricular pacing for 4–8 weeks generated tachycardia-induced cardiomyopathy (TIC) with signs of decompensated heart failure (HF) which was denoted by baseline values of cardiac output 2.9 ± 0.4 L/min at rest, severe dilation of all heart chambers, valves insufficiency, and systemic hypotension
Left ventricular ejection fraction (EF) evaluated by echocardiography was below 30% in all animals; initial mean heart rate of sinus rhythm was 100 ± 19 beats/min; dyssynchrony of LV contraction was obvious
Summary
Venoarterial extracorporeal membrane oxygenation (VA ECMO) is widely used in the treatment of circulatory failure, but repeatedly, its negative effects on the left ventricle (LV) have been observed. Increasing VA ECMO blood flow seems to negatively impact left ventricular (LV) performance; it has been suggested to use only the lowest possible rate of circulatory support to protect myocardial function [8, 10]. Several causes for this negative effect have been repeatedly suspected. The inflow of blood reaches the aortic root and increases the mean aortic pressure and the LV afterload These factors, together with preload and coronary perfusion, play key roles in heart performance. Additional mitral regurgitation may contribute to rise in left atrial pressure; pulmonary congestion may appear as a feared complication of VA ECMO [16,17,18]
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