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Patients With Continuous-Flow Left Ventricular Assist Devices Provide Insight in Human Baroreflex Physiology.
MedLine Citation:
PMID:  22824986     Owner:  NLM     Status:  Publisher    
The superior clinical outcome of new continuous-flow left ventricular assist devices (LVADs) challenges the physiological dogma that cardiovascular autonomic homeostasis requires pulsatile blood flow and pressure. We tested the hypothesis that continuous-flow LVADs impair baroreflex control of sympathetic nerve traffic, thus further exacerbating sympathetic excitation. We included 9 male heart failure patients (26-61 years; 18.9-28.3 kg/m(2)) implanted with a continuous-flow LVAD. We recorded ECG, respiration, finger blood pressure, brachial blood pressure, and muscle sympathetic nerve activity. After baseline measurements had been taken, patients underwent autonomic function testing including deep breathing, a Valsalva maneuver, and 15° head-up tilt. Finally, we increased the LVAD speed in 7 patients. Spontaneous sympathetic baroreflex sensitivity was analyzed. Brachial blood pressure was 99±4 mm Hg with 14±2 mm Hg finger pulse pressure. Muscle sympathetic nerve activity bursts showed a normal morphology, were linked to the cardiac cycle, and were suppressed during blood pressure increases. Mean burst frequency was lower compared with age- and body mass index-matched controls in 2 patients, slightly increased in 4 patients, and increased in 2 patients (P=0.11). Muscle sympathetic nerve activity burst latency and the median values of the burst amplitude distribution were similar between groups. Muscle sympathetic nerve activity increased 4±1 bursts per minute with head-up tilt (P<0.0003) and decreased 3±4 bursts per minute (P<0.031) when LVAD speed was raised. The mean sympathetic baroreflex slope was -3.75±0.79%/mm Hg in patients and -3.80±0.55%/mm Hg in controls. We conclude that low pulse pressure levels are sufficient to restrain sympathetic nervous system activity through baroreflex mechanisms.
Jens Tank; Karsten Heusser; Doris Malehsa; Katrin Hegemann; Sven Haufe; Julia Brinkmann; Uwe Tegtbur; André Diedrich; Christoph Bara; Jens Jordan; Martin Strüber
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-7-23
Journal Detail:
Title:  Hypertension     Volume:  -     ISSN:  1524-4563     ISO Abbreviation:  -     Publication Date:  2012 Jul 
Date Detail:
Created Date:  2012-7-24     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7906255     Medline TA:  Hypertension     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Institute of Clinical Pharmacology, Department of Cardiac, Thoracic, Transplantation, and Vascular Surgery, and Institute of Sports Medicine, Hannover Medical School, Hannover, Germany; Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, TN.
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