ASAIO journal : a peer-reviewed journal of the American Society for Artificial Internal Organs
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Comparative Study
Hemodynamic and pressure-volume responses to continuous and pulsatile ventricular assist in an adult mock circulation.
This study investigated the hemodynamic and left ventricular (LV) pressure-volume loop responses to continuous versus pulsatile assist techniques at 50% and 100% bypass flow rates during simulated ventricular pathophysiologic states (normal, failing, recovery) with Starling response behavior in an adult mock circulation. The rationale for this approach was the desire to conduct a preliminary investigation in a well controlled environment that cannot be as easily produced in an animal model or clinical setting. Continuous and pulsatile flow ventricular assist devices (VADs) were connected to ventricular apical and aortic root return cannulae. ⋯ At full bypass flow (100%) for both assist devices, there was a pronounced effect on hemodynamic parameters, whereas the lesser bypass flow (50%) had only a slight influence. Hemodynamic responses to continuous and pulsatile assist during simulated heart failure differed from normal and recovery states. These findings suggest the potential for differences in endocardial perfusion between assist techniques that may warrant further investigation in an in vivo model, the need for controlling the amount of bypass flow, and the importance in considering the choice of in vivo model.
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A need exists for a mock circulation that behaves in a physiologic manner for testing cardiac devices in normal and pathologic states. To address this need, an integrated mock cardiovascular system consisting of an atrium, ventricle, and systemic and coronary vasculature was developed specifically for testing ventricular assist devices (VADs). This test configuration enables atrial or ventricular apex inflow and aortic outflow cannulation connections. ⋯ Results demonstrated that the mock ventricle pressure-volume loops and the end diastolic and end systolic pressure-volume relationships are representative of the Starling characteristics of the natural heart for each of the test conditions. The mock vasculature can be configured to mimic the input impedance and mechanical properties of native vasculature in the normal state. Although mock circulation testing systems cannot replace in vivo models, this configuration should be well suited for developing experimental protocols, testing device feedback control algorithms, investigating flow profiles, and training surgical staff on the operational procedures of cardiovascular devices.
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Clinical Trial
Impact of high volume hemofiltration on hemodynamic disturbance and outcome during septic shock.
The purpose of this study was to evaluate the effect of high volume continuous venovenous hemofiltration (HVCVVH) on hemodynamic and outcome in patients with septic shock. The primary end point was mortality at 28 days. Study design was a prospective case series, and study setting was a 12 bed intensive care unit at a university hospital. ⋯ The predicted 28 day mortality by three different severity scores was more than 70%, and the mortality in the hemofiltration group was 46% (p < 0.075). In the present study of septic shock patients with organ dysfunction, the hemodynamic parameters increased regularly during treatment by HVCVVH. This study suggests a beneficial effect of HVCVVH on 28 day mortality (46% vs. 70%), and further studies with larger cohorts are required.