Document Detail

Overnight heart rate and cardiac function in patients with dual chamber pacemakers.
MedLine Citation:
PMID:  8734750     Owner:  NLM     Status:  MEDLINE    
Animal data indicate that chronic, overnight pacing at normal evening heart rates impairs cardiac function. We examined the relationship of pacing rate and cardiac function in nine patients with dual-chamber pacemakers. We investigated two, 3-week pacing regimens (80 and 50 ppm: DDD mode) in a cross-over design. Doppler echocardiograms were performed at 1700 hours (PM) and 0600 hours (AM) at the end of each regimen. Ventricular function and preload decreased overnight (PM vs AM) with both pacing regimens. Compared to the morning values, the ratio of preejection to ejection time (PEP/ET) rose (0.43 vs 0.46), while the mean velocity of circumferential fiber shortening (Vcf) fell (1.16 cm/s vs 1.11 cm/s). Stroke volume (SV) (61 mL vs 53 mL) and ejection fraction (EF) also fell (0.56 vs 0.53) in the morning. End-diastolic volume (EDV) (94 mL vs 88 mL) decreased in the morning, as did the ratio of passive to active filling (E/A) (1.06 vs 0.96). Isovolumic relaxation time (91 ms vs 101 ms) increased overnight at both pacing rates. Systolic function decreased at 80 ppm relative to 50 ppm at both times of day. SV fell (54 mL vs 61 mL), while both EDV (92 mL vs 90 mL) end-systolic volume (ESV) increased (43 mL vs 40 mL). Contractility measured by Vcf (1.09 cm/s vs 1.18 cm/s) and PEP/ET (0.49 vs 0.41) was reduced at 80 ppm. The heart needs to rest at night by slowing its rate of contraction. Pacing at 80 ppm impairs systolic and diastolic ventricular function compared to 50 ppm. Longer term consequences of ostensibly physiological pacing rates merit inquiry, particularly in those with preexisting cardiac dysfunction.
P H Chew; D E Bush; B T Engel; M I Talan; R T Abell
Publication Detail:
Type:  Clinical Trial; Comparative Study; Journal Article; Randomized Controlled Trial; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Pacing and clinical electrophysiology : PACE     Volume:  19     ISSN:  0147-8389     ISO Abbreviation:  Pacing Clin Electrophysiol     Publication Date:  1996 May 
Date Detail:
Created Date:  1996-10-21     Completed Date:  1996-10-21     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  7803944     Medline TA:  Pacing Clin Electrophysiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  822-8     Citation Subset:  IM    
Laboratory of Behavioral Sciences, National Institute on Aging, National Institutes of Health, Gerontology Research Center, Baltimore, Maryland 21224, USA.
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MeSH Terms
Cardiac Output
Cardiac Pacing, Artificial / methods
Cardiac Volume
Circadian Rhythm*
Cross-Over Studies
Echocardiography, Doppler
Heart / physiology*
Heart Rate*
Middle Aged
Myocardial Contraction
Pacemaker, Artificial*
Single-Blind Method
Stroke Volume
Ventricular Function
Grant Support
Erratum In:
Pacing Clin Electrophysiol 1996 Aug;19(8):viii

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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