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      Why pulsatility still matters: a review of current knowledge

      review-article
      Croatian Medical Journal
      Croatian Medical Schools

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          Abstract

          Continuous-flow left ventricular assist devices (LVAD) have become standard therapy option for patients with advanced heart failure. They offer several advantages over previously used pulsatile-flow LVADs, including improved durability, less surgical trauma, higher energy efficiency, and lower thrombogenicity. These benefits translate into better survival, lower frequency of adverse events, improved quality of life, and higher functional capacity of patients. However, mounting evidence shows unanticipated consequences of continuous-flow support, such as acquired aortic valve insufficiency and acquired von Willebrand syndrome. In this review article we discuss current evidence on differences between continuous and pulsatile mechanical circulatory support, with a focus on clinical implications and potential benefits of pulsatile flow.

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          Most cited references93

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          Acquired von Willebrand syndrome in aortic stenosis.

          Aortic-valve stenosis can be complicated by bleeding that is associated with acquired type 2A von Willebrand syndrome. However, the prevalence and cause of the hemostatic abnormality in aortic stenosis are unknown. We enrolled 50 consecutive patients with aortic stenosis, who completed a standardized screening questionnaire to detect a history of bleeding. Forty-two patients with severe aortic stenosis underwent valve replacement. Platelet function under conditions of high shear stress, von Willebrand factor collagen-binding activity and antigen levels, and the multimeric structure of von Willebrand factor were assessed at base line and one day, seven days, and six months postoperatively. Skin or mucosal bleeding occurred in 21 percent of the patients with severe aortic stenosis. Platelet-function abnormalities under conditions of high shear stress, decreased von Willebrand factor collagen-binding activity and the loss of the largest multimers, or a combination of these was present in 67 to 92 percent of patients with severe aortic stenosis and correlated significantly with the severity of valve stenosis. Primary hemostatic abnormalities were completely corrected on the first day after surgery but tended to recur at six months, especially when there was a mismatch between patient and prosthesis (with an effective orifice area of less than 0.8 cm2 per square meter of body-surface area). Type 2A von Willebrand syndrome is common in patients with severe aortic stenosis. Von Willebrand factor abnormalities are directly related to the severity of aortic stenosis and are improved by valve replacement in the absence of mismatch between patient and prosthesis. Copyright 2003 Massachusetts Medical Society
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            Left ventricular assist device and drug therapy for the reversal of heart failure.

            In patients with severe heart failure, prolonged unloading of the myocardium with the use of a left ventricular assist device has been reported to lead to myocardial recovery in small numbers of patients for varying periods of time. Increasing the frequency and durability of myocardial recovery could reduce or postpone the need for subsequent heart transplantation. We enrolled 15 patients with severe heart failure due to nonischemic cardiomyopathy and with no histologic evidence of active myocarditis. All had markedly reduced cardiac output and were receiving inotropes. The patients underwent implantation of left ventricular assist devices and were treated with lisinopril, carvedilol, spironolactone, and losartan to enhance reverse remodeling. Once regression of left ventricular enlargement had been achieved, the beta2-adrenergic-receptor agonist clenbuterol was administered to prevent myocardial atrophy. Eleven of the 15 patients had sufficient myocardial recovery to undergo explantation of the left ventricular assist device a mean (+/-SD) of 320+/-186 days after implantation of the device. One patient died of intractable arrhythmias 24 hours after explantation; another died of carcinoma of the lung 27 months after explantation. The cumulative rate of freedom from recurrent heart failure among the surviving patients was 100% and 88.9% 1 and 4 years after explantation, respectively. The quality of life as assessed by the Minnesota Living with Heart Failure Questionnaire score at 3 years was nearly normal. Fifty-nine months after explantation, the mean left ventricular ejection fraction was 64+/-12%, the mean left ventricular end-diastolic diameter was 59.4+/-12.1 mm, the mean left ventricular end-systolic diameter was 42.5+/-13.2 mm, and the mean maximal oxygen uptake with exercise was 26.3+/-6.0 ml per kilogram of body weight per minute. In this single-center study, we found that sustained reversal of severe heart failure secondary to nonischemic cardiomyopathy could be achieved in selected patients with the use of a left ventricular assist device and a specific pharmacologic regimen. Copyright 2006 Massachusetts Medical Society.
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              Extended mechanical circulatory support with a continuous-flow rotary left ventricular assist device.

              This study sought to evaluate the use of a continuous-flow rotary left ventricular assist device (LVAD) as a bridge to heart transplantation. LVAD therapy is an established treatment modality for patients with advanced heart failure. Pulsatile LVADs have limitations in design precluding their use for extended support. Continuous-flow rotary LVADs represent an innovative design with potential for small size and greater reliability by simplification of the pumping mechanism. In a prospective, multicenter study, 281 patients urgently listed (United Network of Organ Sharing status 1A or 1B) for heart transplantation underwent implantation of a continuous-flow LVAD. Survival and transplantation rates were assessed at 18 months. Patients were assessed for adverse events throughout the study and for quality of life, functional status, and organ function for 6 months. Of 281 patients, 222 (79%) underwent transplantation, LVAD removal for cardiac recovery, or had ongoing LVAD support at 18-month follow-up. Actuarial survival on support was 72% (95% confidence interval: 65% to 79%) at 18 months. At 6 months, there were significant improvements in functional status and 6-min walk test (from 0% to 83% of patients in New York Heart Association functional class I or II and from 13% to 89% of patients completing a 6-min walk test) and in quality of life (mean values improved 41% with Minnesota Living With Heart Failure and 75% with Kansas City Cardiomyopathy questionnaires). Major adverse events included bleeding, stroke, right heart failure, and percutaneous lead infection. Pump thrombosis occurred in 4 patients. A continuous-flow LVAD provides effective hemodynamic support for at least 18 months in patients awaiting transplantation, with improved functional status and quality of life. (Thoratec HeartMate II Left Ventricular Assist System [LVAS] for Bridge to Cardiac Transplantation; NCT00121472).

                Author and article information

                Journal
                Croat Med J
                Croat. Med. J
                CMJ
                Croatian Medical Journal
                Croatian Medical Schools
                0353-9504
                1332-8166
                December 2014
                : 55
                : 6
                : 609-620
                Affiliations
                [1]Department of Cardiac Surgery and Transplantation, Dubrava University Hospital, Zagreb, Croatia
                Author notes
                Correspondence to:
Davor Barić
Department of Cardiac Surgery and Transplantation 
Dubrava University Hospital 
Avenija Gojka Šuška 6
10000 Zagreb, Croatia 
 dbaric@ 123456kbd.hr
                Article
                CroatMedJ_55_0609
                10.3325/cmj.2014.55.609
                4295069
                25559832
                f53a2e8a-5bcd-4a02-b3c6-6eec183916cd
                Copyright © 2014 by the Croatian Medical Journal. All rights reserved.

                This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

                History
                : 17 July 2014
                : 15 November 2014
                Categories
                Advanced Heart Failure

                Medicine
                Medicine

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