Amacher R Weber A Brinks H Axiak S Ferreira A Guzzella L Carrel T Antaki J Vandenberghe S 2013 OBJECTIVE Current pulsatile ventricular assist devices operate asynchronous with the left ventricle in fixed-rate or fill-to-empty modes because electrocardiogram-triggered modes have been abandoned. We hypothesize that varying the ejection delay in the synchronized mode yields more precise control of hemodynamics and left ventricular loading. This allows for a refined management that may be clinically beneficial. METHODS Eight sheep received a Thoratec paracorporeal ventricular assist device (Thoratec Corp, Pleasanton, Calif) via ventriculo-aortic cannulation. Left ventricular pressure and volume, aortic pressure, pulmonary flow, pump chamber pressure, and pump inflow and outflow were recorded. The pump was driven by a clinical pneumatic drive unit (Medos Medizintechnik AG, Stolberg, Germany) synchronously with the native R-wave. The start of pump ejection was delayed between 0% and 100% of the cardiac period in 10% increments. For each of these delays, hemodynamic variables were compared with baseline data using paired t tests. RESULTS The location of the minimum of stroke work was observed at a delay of 10% (soon after aortic valve opening), resulting in a median of 43% reduction in stroke work compared with baseline. Maximum stroke work occurred at a median delay of 70% with a median stroke work increase of 11% above baseline. Left ventricular volume unloading expressed by end-diastolic volume was most pronounced for copulsation (delay 0%). CONCLUSIONS The timing of pump ejection in synchronized mode yields control over left ventricular energetics and can be a method to achieve gradual reloading of a recoverable left ventricle. The traditionally suggested counterpulsation is not optimal in ventriculo-aortic cannulation when maximum unloading is desired. application/pdf https://sonar.ch/global/documents/143412 eng info:eu-repo/semantics/altIdentifier/doi/10.1016/j.jtcvs.2012.12.048 info:eu-repo/semantics/altIdentifier/pmid/23317942 info:eu-repo/semantics/openAccess The Journal of thoracic and cardiovascular surgery. - 2013 27 ECG LV LVAD VAD electrocardiogram left ventricle left ventricular assist device ventricular assist device Animals Aorta Arterial Pressure Disease Models, Animal Electrocardiography Heart Rate Heart-Assist Devices Prosthesis Design Pulmonary Circulation Pulsatile Flow Regional Blood Flow Sheep Stroke Volume Time Factors Ventricular Dysfunction, Left Ventricular Function, Left Ventricular Pressure Control of ventricular unloading using an electrocardiogram-synchronized Thoratec paracorporeal ventricular assist device. http://purl.org/coar/resource_type/c_6501