Dataset Information

LVAD Pump Flow Does Not Adequately Increase With Exercise.

ABSTRACT: Left ventricular assist devices (LVADs) restore cardiovascular circulatory demand at rest with a spontaneous increase in pump flow to exercise. The relevant contribution of cardiac output provided by the LVAD and ejected through the aortic valve for exercises of different intensities has been barely investigated in patients. The hypothesis of this study was that different responses in continuous recorded pump parameters occur for maximal and submaximal intensity exercises and that the pump flow change has an impact on the oxygen uptake at peak exercise (pVO2 ). Cardiac and pump parameters such as LVAD flow rate (QLVAD ), heart rate (HR), and aortic valve (AV) opening were analyzed from continuously recorded LVAD data during physical exercises of maximal (bicycle ergometer test) and submaximal intensities (6-min walk test and regular trainings). During all exercise sessions, the LVAD speed was kept constant. Cardiac and pump parameter responses of 16 patients for maximal and submaximal intensity exercises were similar for QLVAD : +0.89 ± 0.52 versus +0.59 ± 0.38 L/min (P = 0.07) and different for HR: +20.4 ± 15.4 versus +7.7 ± 5.8 bpm (P < 0.0001) and AV-opening with 71% versus 23% of patients (P < 0.0001). Multi-regression analysis with pVO2 (R2 = 0.77) showed relation to workload normalized by bodyweight (P = 0.0002), HR response (P = 0.001), AV-opening (P = 0.02), and age (P = 0.06) whereas the change in QLVAD was irrelevant. Constant speed LVADs provide inadequate support for maximum intensity exercises. AV-opening and improvements in HR show an important role for higher exercise capacities and reflect exercise intensities. Changes in pump flow do not impact pVO2 and are independent of AV-opening and response in HR. An LVAD speed control may lead to adequate left ventricular support during strenuous physical activities.

SUBMITTER: Gross C

PROVIDER: S-EPMC6589923 | biostudies-literature | 2019 Mar

REPOSITORIES: biostudies-literature

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LVAD Pump Flow Does Not Adequately Increase With Exercise.

Gross Christoph C Marko Christiane C Mikl Johann J Altenberger Johann J Schlöglhofer Thomas T Schima Heinrich H Zimpfer Daniel D Moscato Francesco F

Artificial organs 20181118 3

Left ventricular assist devices (LVADs) restore cardiovascular circulatory demand at rest with a spontaneous increase in pump flow to exercise. The relevant contribution of cardiac output provided by the LVAD and ejected through the aortic valve for exercises of different intensities has been barely investigated in patients. The hypothesis of this study was that different responses in continuous recorded pump parameters occur for maximal and submaximal intensity exercises and that the pump flow ...[more]

PMID: 30155903

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Project description:BACKGROUND:There are animal data suggesting green tea can enhance blood flow. However, human data are lacking. Thus, the purpose of this study was to examine the acute effects of low and high doses of a green tea-based supplement (GBS) on brachial artery blood flow before and following a resistance exercise bout. METHODS:In this, double-blinded placebo-controlled trial, college-aged males (n?=?18) who self-reported recreationally resistance training for the previous 6?±?3?years were assigned to one of two studies including a low (300?mg serving) (n?=?9) or high dose (600?mg serving) (n?=?8; 1 drop) GBS study. During testing sessions, participants reported to the laboratory following an overnight fast and rested in a supine position for 15?min. Thereafter, baseline measurements for resting heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), brachial artery diameter (BAD) and blood flow (BBF) were obtained (PRE). Participants then consumed either their respective GBS dose or a similar placebo dose (microcrystalline cellulose) in a supine resting state. HR, SBP, DBP, BAD and BBF were measured 45?min after placebo or GBS ingestion (PRE2). Participants were then placed in a recumbent position and performed 4 sets of 10 arm curl repetitions using an 11?kg dumbbell. Participants returned to a supine position and HR, SBP, DBP, BAD and BBF were obtained within the first 3?min following exercise (POST), 15?min after exercise (15POST), and 45?min after exercise (45POST). Participants returned to the laboratory 24-48?h later to repeat the same protocol with either GBS or the placebo depending on randomization. Two-way (supplement x time) repeated measures ANOVAs were used to compare dependent variables between testing sessions for Study 1 (300?mg of GBS and placebo) and Study 2 (600?mg of GBS and placebo), and statistical significance was set at p?<?0.05. No statistical comparisons were made between studies. RESULTS:As expected, exercise increased BAD and BBF compared to resting baseline measured irrespective of supplementation. In addition, BAD and BBF did not differ between GBS and placebo at any time point after exercise in Study 1. In study 2, however, 600?mg GBS increased baseline-normalized BBF at immediately post exercise compared to placebo (placebo?=?211?±?155% increase, GBS?=?349?±?156% increase; p?=?0.012) but not BAD. CONCLUSIONS:These data suggest a higher dose of GBS can enhance localized blood flow acutely following a resistance exercise bout. However, the long-term implications of these data are unclear, and more well-powered studies are needed to validate efficacy and elucidate potential mechanisms.

Dataset Information

LVAD Pump Flow Does Not Adequately Increase With Exercise.

Publications

LVAD Pump Flow Does Not Adequately Increase With Exercise.

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