PM&R
Volume 1, Issue 9 , Pages 820-826, September 2009

Incongruous Changes in Heart Period and Heart Rate Variability with Vagotonic Atropine: Implications for Rehabilitation Medicine

  • Glen Picard, MA

      Affiliations

    • Cardiovascular Research Laboratory, Spaulding Rehabilitation Hospital, Boston, MA†
    • ,
  • Can Ozan Tan, PhD

      Affiliations

    • Cardiovascular Research Laboratory, Spaulding Rehabilitation Hospital, Boston, MA‡
    • ,
  • Ross Zafonte, DO

      Affiliations

    • Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA§
    • ,
  • J. Andrew Taylor, PhD

      Affiliations

    • Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA; Cardiovascular Research Laboratory, Spaulding Rehabilitation Hospital, 125 Nashua St, Boston, MA 02114
    • Corresponding Author InformationAddress correspondence to: J.A.T.

Received 22 May 2009; accepted 12 July 2009.

Objective

To describe the relationship between vagally mediated bradycardia and heart rate variability indices in young and older healthy individuals.

Design

Cross-sectional, physiologic study.

Setting

Outpatient cardiovascular research laboratory.

Participants

A total of 34 young (mean age 24 years) and 27 older (mean age 63 years) healthy adults.

Methods

Eight bolus injections of atropine sulfate were given intravenously to participants while in a supine position (cumulative doses from 0.4 to 7.2 μg/kg). Each dose was followed by a 3-minute data collection period in which subjects controlled their breathing frequency at a rate of 15 breaths per minute.

Main Outcome Measurements

Chronotropic responses were assessed from average RR interval and blood pressure was assessed by automated brachial cuff. Heart rate variability (HRV) indices were calculated to represent both time domain measures (RR interval standard deviation and root mean squared of successive differences) and frequency domain measures (respiratory sinus arrhythmia and total power).

Results

RR interval responses exhibited the expected curvilinear pattern to atropine administration with all subjects exhibiting a bradycardia with at least one dose and RR interval returning to baseline or decreasing in most subjects as atropine dosing progressed. RR interval was closely related to vagotonic atropine dose with an r2 greater than 0.70 in 89% of subjects. Heart rate variability indices were not consistently correlated with the bradycardic effect of vagotonic atropine and ranged from highly positive to highly negative with almost one-fifth of correlations less than 0.5.

Conclusions

The relationship between HRV and vagal tone is likely complex and has a large interindividual variation.

To access this article, please choose from the options below

Login to an existing account or Register a new account.

  • Purchase this article for 31.50 USD (You must login/register to purchase this article)

    Online access for 24 hours. The PDF version can be downloaded as your permanent record.

  • Subscribe to this title

    Get unlimited online access to this article and all other articles in this title 24/7 for one year.

  • Claim access now

    For current subscribers with Society Membership or Account Number.

  • Visit SciVerse ScienceDirect to see if you have access via your institution.
 
  • † Disclosure: nothing to disclose
  • ‡ Disclosure: nothing to disclose
  • § Disclosure: nothing to disclose
  •  Disclosure: 8B, NIH

 Supported by the National Institutes of Health, National Institute on Aging (grant AG014376).

 Disclosure Key can be found on the Table of Contents and at www.pmrjournal.org

PII: S1934-1482(09)00712-6

doi:10.1016/j.pmrj.2009.07.017

PM&R
Volume 1, Issue 9 , Pages 820-826, September 2009

Article Tools

* Image Usage & Resolution