ASAIO journal : a peer-reviewed journal of the American Society for Artificial Internal Organs
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Debate exists regarding the merits and limitations of continuous versus pulsatile flow mechanical circulatory support. To characterize the hemodynamic differences between each mode of support, we investigated the acute effects of continuous versus pulsatile unloading of the failing left ventricle in a bovine model. Heart failure was induced in male calves (n = 14). ⋯ However, a normal range of left ventricular pressures was preserved. Continuous unloading deranged the physiologic profile of myocardial and vascular hemodynamic energy utilization, whereas pulsatile unloading preserved more normal physiologic values. These findings may have important implications for chronic LVAD therapy.
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Comparative Study
Comparative analysis of von Willebrand factor profiles in pulsatile and continuous left ventricular assist device recipients.
A higher rate of nonsurgical bleeding has been observed in nonpulsatile left ventricular assist device (LVAD) recipients. von Willebrand factor (vWF) profiles were compared for nonpulsatile and pulsatile LVAD recipients to explore mechanisms that may contribute to the development of postimplant nonsurgical bleeding. The nonpulsatile mechanism may impair vWF function by creating a deficiency in vWF high molecular weight multimers (HMWMs), essential for hemostasis. High molecular weight multimer deficiency should result in low ristocetin cofactor (RCo) to vWF antigen ratios (vWF:RCo/vWF:Ag) because of impaired platelet (plt)-binding ability. von Willebrand factor profiles and HMWM were measured pre- and post-LVAD placement in 11 nonpulsatile (HeartMate II [HM II[) and 3 pulsatile (HeartMate XVE [HM XVE]) recipients. ⋯ Similar results were not observed in our small series of pulsatile HM XVE recipients. This finding could suggest a contributing factor to the increase in nonsurgical bleeding observed in nonpulsatile LVAD patients. Further investigation is ongoing to identify specific causes of vWF impairment.
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Fluid overload is a frequent finding in critically ill patients suffering from acute kidney injury (AKI). To assess the impact of fluid overload on the mortality of AKI patients treated with continuous renal replacement therapy (CRRT), we used a registry of 81 critically ill patients with AKI initiated on CRRT assembled over an 18-month period to conduct a cross- sectional analysis using volume-related weight gain (VRWG) of > or =10% and > or =20% of body weight and oliguria (< or =20 ml/h) as the principal variables, with the primary outcome measure being mortality at 30 days. Mean Apache II scores were 27.5 +/- 6.9 with overall cohort mortality of 50.6%. ⋯ Both VRWG > or =10% (OR 2.71, p = 0.040) and oliguria (OR 3.04, p = 0.032) maintained their statistically significant association with mortality in multivariate models that included sepsis and Apache II score. In conclusion, fluid overload is an important prognostic factor for survival in critically ill AKI patients treated with CRRT. Further studies are needed to elicit mechanisms and develop appropriate interventions.
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Since 2005, we have used a novel technique based on the closed cardiopulmonary bypass system without cardiotomy suction (minimal cardiopulmonary bypass [mini-CPB]) for aortic valve replacement (AVR). In this study, we investigated the clinical advantages of this approach. We prospectively studied 32 patients who underwent isolated AVR using the mini-CPB (group M, n = 13) or conventional CPB (group C, n = 19). ⋯ There were no differences in IL-8 or blood transfusion volume after CPB. Mini-CPB offers an alternative to conventional CPB for AVR and has some advantages regarding hemodilution and serum IL-6 levels. However, it is unlikely to become the standard approach for AVR because there are no marked clinical advantages of mini-CPB.
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A low-resistance membrane oxygenator [interventional lung assist (iLA), Novalung, Hirrlingen, Germany] has been placed in series with a pulsatile extracorporeal left ventricular assist device (LVAD, Berlin Heart EXCOR, Berlin, Germany) in 1 circuit in a patient with postcardiotomy cardiopulmonary failure subsequent to 5 days of extracorporeal life support (ECLS or ECMO). This concept offers an intermediate step between ECLS and mechanical ventilation in this particular patient population. ⋯ As a result, mechanical ventilation became sufficient after 48 hours, and the iLA was then removed easily out of the circuit. In conclusion, this case demonstrates the feasibility of integrating a low-resistance membrane oxygenator for additional lung support in extracorporeal LVAD patients.