Physiology of continuous blood flow in recipients of rotary cardiac assist devices

Thalmann, Markus; Schima, Heinrich; Wieselthaler, Georg; Wolner, Ernst

doi:10.1016/j.healun.2004.04.018

Cited by 53 publications

(38 citation statements)

References 64 publications

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“…Moreover, depulsation per se has effects that may confound interpretations. Many early studies have shown this maneuver to reduce renal cortical blood flow and GFR and to stimulate renin (52,101,104), observations confirmed by recent studies (e.g., 111,149,155). Investigations specifically designed to critically evaluate the influences of mean vs. systolic BP signals on myogenic tone in vivo are needed and currently lacking.…”

Section: Renal Myogenic Response To the Oscillating Systolic Pressurementioning

confidence: 90%

Renal autoregulation: new perspectives regarding the protective and regulatory roles of the underlying mechanisms

Loutzenhiser

Griffin²,

Bidani³

2006

American Journal of Physiology-Regulatory, Integrative and Comp

238

244

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dani. Renal autoregulation: new perspectives regarding the protective and regulatory roles of the underlying mechanisms. Am J Physiol Regul Integr Comp Physiol 290: R1153-R1167, 2006. doi:10.1152/ajpregu.00402.2005.-When the kidney is subjected to acute increases in blood pressure (BP), renal blood flow (RBF) and glomerular filtration rate (GFR) are observed to remain relatively constant. Two mechanisms, tubuloglomerular feedback (TGF) and the myogenic response, are thought to act in concert to achieve a precise moment-by-moment regulation of GFR and distal salt delivery. The current view is that this mechanism insulates renal excretory function from fluctuations in BP. Indeed, the concept that renal autoregulation is necessary for normal renal function and volume homeostasis has long been a cornerstone of renal physiology. This article presents a very different view, at least regarding the myogenic component of this response. We suggest that its primary purpose is to protect the kidney against the damaging effects of hypertension. The arguments advanced take into consideration the unique properties of the afferent arteriolar myogenic response that allow it to protect against the oscillating systolic pressure and the accruing evidence that when this response is impaired, the primary consequence is not a disturbed volume homeostasis but rather an increased susceptibility to hypertensive injury. It is suggested that redundant and compensatory mechanisms achieve volume regulation, despite considerable fluctuations in distal delivery, and the assumed moment-by-moment regulation of renal hemodynamics is questioned. Evidence is presented suggesting that additional mechanisms exist to maintain ambient levels of RBF and GFR within normal range, despite chronic alterations in BP and severely impaired acute responses to pressure. Finally, the implications of this new perspective on the divergent roles of the myogenic response to pressure vs. the TGF response to changes in distal delivery are considered, and it is proposed that in addition to TGF-induced vasoconstriction, vasodepressor responses to reduced distal delivery may play a critical role in modulating afferent arteriolar reactivity to integrate the regulatory and protective functions of the renal microvasculature. renal microcirculation; afferent arteriole; myogenic; tubuloglomerular feedback ONE OF THE MOST STRIKING CHARACTERISTICS of the renal circulation is the ability of the kidney to maintain a constant renal blood flow (RBF) and glomerular filtration rate (GFR) as renal perfusion pressure is altered. The dual regulation of both RBF and GFR is achieved by proportionate changes in the preglomerular resistance and is believed to be mediated by two mechanisms, tubuloglomerular feedback (TGF) and the renal myogenic response. TGF involves a flow-dependent signal that is sensed at the macula densa and alters tone in the adjacent segment of the afferent arteriole via a mechanism that remains controversial but likely involves adenosine and/or ATP (30,80,144). The myo...

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Section: Renal Myogenic Response To the Oscillating Systolic Pressurementioning

confidence: 90%

Renal autoregulation: new perspectives regarding the protective and regulatory roles of the underlying mechanisms

Loutzenhiser

Griffin²,

Bidani³

2006

American Journal of Physiology-Regulatory, Integrative and Comp

238

244

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“…The effect of LVAD therapy on kidney function and physiology has been studied recently with conflicting results and without a clear pathophysiological understanding [11,12,13,14,15,16,17,18,19]. One current limitation to studying this pathophysiology is that LVAD implantation trends have changed from historically pulsatile to exclusively continuous flow device types.…”

Section: What Effect Does Lvad Physiology Have On Kidney Function?mentioning

confidence: 99%

“…An increased diastolic pressure is a key difference that, in combination with RV failure and venous congestion, could be critical in the development of kidney dysfunction. Despite the relatively fixed impeller speeds in CF-LVADs, there is a variable degree of pulsatile blood flow generated from the residual effects of native myocardial contractility [16,17]. Overall, the circulatory effects of CF-LVAD support result in an increased systemic mean arterial pressure and improvements in kidney perfusion [18].…”

Section: What Effect Does Lvad Physiology Have On Kidney Function?mentioning

confidence: 99%

Kidney Dysfunction and Left Ventricular Assist Device Support: A Comprehensive Perioperative Review

et al. 2015

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Left ventricular assist devices (LVADs) are used increasingly as a bridge to transplantation or as destination therapy in end-stage heart failure patients who do not respond to optimal medical therapy. Many of these patients have end-organ dysfunction, including advanced kidney dysfunction, before and after LVAD implantation. Kidney dysfunction is a marker of adverse outcomes, such as increased morbidity and mortality. This review discusses kidney dysfunction and associated management strategies during the dynamic perioperative time period of LVAD implantation. Furthermore, we suggest potential future research directions to better understand the complex relationship between renal pathophysiology and mechanical circulatory support.

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“…The evolution from pulsatile to continuousflow LVADs has not been without concern due to the nonphysiologic nature of continuous blood flow (31). In actuality, blood flow in continuous-flow LVAD recipients has some pulsatility, albeit low, from residual unloaded native left ventricular function (31,32). Continuous-flow LVADs increase diastolic pressure and flow and lower peak systolic pressure resulting in a dampening of pulsatility and an increase in laminar flow (33).…”

Section: Continuous Blood Flow and Renal Functionmentioning

confidence: 99%

Renal Failure in Patients with Left Ventricular Assist Devices

Patel

Adeseun

Ahmed

et al. 2013

Clinical Journal of the American Society of Nephrology

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SummaryImplantable left ventricular assist devices (LVADs) are increasingly being used as a bridge to transplantation or as destination therapy in patients with end stage heart failure refractory to conventional medical therapy. A significant number of these patients have associated renal dysfunction before LVAD implantation, which may improve after LVAD placement due to enhanced perfusion. Other patients develop AKI after implantation. LVAD recipients who develop AKI requiring renal replacement therapy in the hospital or who ultimately require longterm outpatient hemodialysis therapy present management challenges with respect to hemodynamics, volume, and dialysis access. This review discusses the mechanics of a continuous-flow LVAD (the HeartMate II), the effects of continuous blood flow on the kidney, renal outcomes of patients after LVAD implantation, dialysis modality selection, vascular access, hemodynamic monitoring during the dialytic procedure, and other issues relevant to caring for these patients.

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Physiology of continuous blood flow in recipients of rotary cardiac assist devices

Cited by 53 publications

References 64 publications

Renal autoregulation: new perspectives regarding the protective and regulatory roles of the underlying mechanisms

Renal autoregulation: new perspectives regarding the protective and regulatory roles of the underlying mechanisms

Kidney Dysfunction and Left Ventricular Assist Device Support: A Comprehensive Perioperative Review

Renal Failure in Patients with Left Ventricular Assist Devices

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