2
views
0
recommends
+1 Recommend
0 collections
    0
    shares
      • Record: found
      • Abstract: not found
      • Article: not found

      Living Without a Pulse : The Vascular Implications of Continuous-Flow Left Ventricular Assist Devices

      Read this article at

      ScienceOpenPublisherPMC
      Bookmark
          There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.

          Abstract

          <p class="first" id="P1">Pulsatility appears to have a teleological role as evolutionary hierarchy favors higher ordered animals with more complex, multi-chamber circulatory systems that generate higher pulse pressure compared to lower ordered animals. Yet despite years of such natural selection, the modern generation of continuous-flow left ventricular assist devices (CF-LVADs) that have been increasingly utilized for the last decade have created a unique physiology characterized by a non-pulsatile, non-laminar blood flow profile with the absence of the usual large elastic artery Windkessel effect during diastole. While outcomes and durability have improved with CF-LVADs, patients supported with CF-LVADs have a high rate of complications that were not as frequently observed with older pulsatile devices including gastrointestinal bleeding from arteriovenous malformations, pump thrombosis, and stroke. Given the apparent fundamental biologic role of the pulse, the purpose of this review is to describe the normal physiology of ventricular-arterial coupling from pulsatile flow, the effects of heart failure on this physiology and the vasculature, and to examine the effects of non-pulsatile blood flow on the vascular system and potential role in complications seen with CF-LVAD therapy. Understanding these concomitant vascular changes with CF-LVADs, may be a key step in improving patient outcomes as modulation of pulsatility and flow characteristics may serve as a novel, yet simple therapy for reducing complications. </p>

          Related collections

          Most cited references66

          • Record: found
          • Abstract: found
          • Article: not found

          Hemodynamics of Mechanical Circulatory Support.

          An increasing number of devices can provide mechanical circulatory support (MCS) to patients with acute hemodynamic compromise and chronic end-stage heart failure. These devices work by different pumping mechanisms, have various flow capacities, are inserted by different techniques, and have different sites from which blood is withdrawn and returned to the body. These factors result in different primary hemodynamic effects and secondary responses of the body. However, these are not generally taken into account when choosing a device for a particular patient or while managing a patient undergoing MCS. In this review, we discuss fundamental principles of cardiac, vascular, and pump mechanics and illustrate how they provide a broad foundation for understanding the complex interactions between the heart, vasculature, and device, and how they may help guide future research to improve patient outcomes.
            Bookmark
            • Record: found
            • Abstract: found
            • Article: not found

            Continuous flow left ventricular assist device improves functional capacity and quality of life of advanced heart failure patients.

            This study sought to assess the impact of continuous flow left ventricular assist devices (LVADs) on functional capacity and heart failure-related quality of life. Newer continuous-flow LVAD are smaller and quieter than pulsatile-flow LVADs. Data from advanced heart failure patients enrolled in the HeartMate II LVAD (Thoratec Corporation, Pleasanton, California) bridge to transplantation (BTT) (n = 281) and destination therapy (DT) (n = 374) trials were analyzed. Functional status (New York Heart Association [NYHA] functional class, 6-min walk distance, patient activity scores), and quality of life (Minnesota Living With Heart Failure [MLWHF] and Kansas City Cardiomyopathy Questionnaires [KCCQ]) were collected before and after LVAD implantation. Compared with baseline, LVAD patients demonstrated early and sustained improvements in functional status and quality of life. Most patients had NYHA functional class IV symptoms at baseline. Following implant, 82% (BTT) and 80% (DT) of patients at 6 months and 79% (DT) at 24 months improved to NYHA functional class I or II. Mean 6-min walk distance in DT patients was 204 m in patients able to ambulate at baseline, which improved to 350 and 360 m at 6 and 24 months. There were also significant and sustained improvements from baseline in both BTT and DT patients in median MLWHF scores (by 40 and 42 U in DT patients, or 52% and 55%, at 6 and 24 months, respectively), and KCCQ overall summary scores (by 39 and 41 U, or 170% and 178%). Use of a continuous flow LVAD in advanced heart failure patients results in clinically relevant improvements in functional capacity and heart failure-related quality of life. Copyright (c) 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
              Bookmark
              • Record: found
              • Abstract: found
              • Article: not found

              Limited maximal exercise capacity in patients with chronic heart failure: partitioning the contributors.

              This study aimed to assess the factors limiting maximal exercise capacity in patients with chronic heart failure (CHF). Maximal exercise capacity, an important index of health in CHF, might be limited by central and/or peripheral factors; however, their contributions remain poorly understood. We studied oxygen (O2) transport and metabolism at maximal cycle (centrally taxing) and knee-extensor (KE) (peripherally taxing) exercise in 12 patients with CHF and 8 healthy control subjects in normoxia and hyperoxia (100% O2). Peak oxygen uptake (VO2) while cycling was 33% lower in CHF patients than in control subjects. By experimental design, peak cardiac output was reduced during KE exercise when compared with cycling (approximately 35%); although muscle mass specific peak leg VO2 was increased equally in both groups (approximately 70%), VO2 in the CHF patients was still 28% lower. Hyperoxia increased O2 carriage in all cases but only facilitated a 7% increase in peak leg VO2 in the CHF patients during cycling, the most likely scenario to benefit from increased O2 delivery. Several relationships, peak leg VO2 (KE + cycle) to capillary-fiber-ratio and capillaries around a fiber to mitochondrial volume, were similar in both groups (r = 0.6-0.7). Multiple independent observations, including a significant skeletal muscle metabolic reserve, suggest skeletal muscle per se contributes minimally to limiting maximal cycle exercise in CHF or healthy control subjects. However, the consistent attenuation of the convective and diffusive components of O2 transport (25% to 30%) in patients with CHF during both cycle and even KE exercise compared with control subjects reveals an underlying peripheral O2 transport limitation from blood to skeletal muscle in this pathology. Copyright 2010 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.
                Bookmark

                Author and article information

                Journal
                Circulation: Heart Failure
                Circ Heart Fail
                Ovid Technologies (Wolters Kluwer Health)
                1941-3289
                1941-3297
                June 2018
                June 2018
                : 11
                : 6
                Affiliations
                [1 ]Division of Cardiology, Department of Medicine (S.N.P., W.K.C, A.V.A.)
                [2 ]Division of Cardiothoracic Surgery, Department of Surgery (J.D.P.)
                [3 ]University of Colorado, Aurora. Vanderbilt Heart and Vascular Institute, Nashville, TN (J.L.).
                [4 ]Consortium for Fibrosis Research and Translation (A.V.A.)
                Article
                10.1161/CIRCHEARTFAILURE.117.004670
                6007027
                29903893
                668de427-5bd8-4a00-8f8e-38a86c13085a
                © 2018
                History

                Comments

                Comment on this article