Relationship of Aortic Valve Opening with Preload and Afterload in Patients Supported with Centrifugal Left Ventricular Assist Devices

Abstract

Aortic valve (AV) opening in patients supported with cfLVADS may be a marker of improved myocardial contractility. We aimed to study if status of aortic valve opening is influenced by right ventricular function, preload and afterload both at rest and exercise with pump speed titration. Patients implanted with an isolated centrifugal cfLVAD undergoing routine right heart catheterisation were recruited. Mean arterial pressure (MAP), mean pulmonary capillary wedge pressure (PCWP) and pulmonary artery pressures were recorded. The pulmonary artery pressure index (PAPI) derived from formula was used as a surrogate for right ventricular function. Aortic valve status was determined by transthoracic echocardiography. Patients then performed graded exercise with supine bicycle ergometer until exhaustion (mean workload 40W) at both baseline and maximum pump speed with all measurements repeated. Patients were divided into two groups: closed or open AV. Thirteen patients were studied, mean age 37.4+/-7.4 yrs. Median NYHA class at time of study was II. Median pump speed at rest was 2600rpm (range 2500-2800). Echo derived baseline left ventricular ejection fraction was similar between both groups, closed AV valve 25+/-7.7, open 24.2+/-8.0%, p=0.86. At rest, there was no significant difference between closed AV and open AV for MAP 82.7+/-6.0 vs 85.2 +/-6.0mmHG, p=0.60, PCWP 14.7+/-0.2 vs 16.8+/-6.0mmHg, p=0.46 and PAPI 2.4+/-0.8 vs 2.9+/-0.9, p=0.33. Similarly, no significant difference was noted in these measures at maximum exercise and at maximum pump speed (median 2925rpm, range 2800-3210). Aortic valve opening in patients supported by cfLVADs is not significantly influenced by afterload or preload at both rest and exercise. The contribution of intrinsic myocardial contractility derived by load independent methods on aortic valve opening is warranted.