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February 1, 1978CirculationOpen Access

Patients with normal adjusted SNRTC consistently had normal IHRs (indicating autonomic abnormalities), while those with abnormal adjusted SNRTC had abnormal IHRs (indicating intrinsic SN dysfunction).

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Why the study?

Can intrinsic heart rate determination using atropine and propranolol distinguish the underlying pathophysiologic mechanisms of sinus node dysfunction in patients with sick sinus syndrome?

Population

17 patients with symptomatic sinus bradycardia (sick sinus syndrome)

Design

Cross-sectional

Authors

JJJay L. JordanIYIchiro YamaguchiWMWilliam J. Mandel

Discussion

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Overview

Adjusted SNRTC may distinguish autonomic from intrinsic sinus node dysfunction; leaves open its role in guiding sick sinus syndrome management.

Key Points

  • To identify the pathophysiologic mechanisms underlying sinus node dysfunction in sick sinus syndrome by evaluating intrinsic heart rate and corrected sinus node recovery time.
  • Determined intrinsic heart rate in 17 patients with symptomatic sinus bradycardia following pharmacological autonomic blockade with intravenous atropine (0.04 mg/kg) and propranolol (0.2 mg/kg).
  • Evaluated corrected sinus node recovery time adjusted for the magnitude and direction of autonomic chronotrophy to differentiate intrinsic sinus node failure from autonomic dysregulation.
  • Patients with normal adjusted corrected sinus node recovery time consistently showed normal intrinsic heart rates, indicating underlying autonomic regulatory abnormalities.
  • Patients with abnormal adjusted corrected sinus node recovery time consistently displayed abnormal intrinsic heart rates, confirming primary intrinsic sinus node dysfunction.

Structured PICO

Can intrinsic heart rate determination using atropine and propranolol distinguish the underlying pathophysiologic mechanisms of sinus node dysfunction in patients with sick sinus syndrome?

P
Population
17 patients with symptomatic sinus bradycardia (sick sinus syndrome)
I
Intervention
Atropine 0.04 mg/kg and propranolol 0.2 mg/kg, i.v.
O
Outcome
Intrinsic heart rate (IHR) and corrected sinus node recovery time (SNRTC)surrogate

Sick sinus syndrome can be caused by either intrinsic sinus node dysfunction or abnormal autonomic regulation, which can be distinguished using intrinsic heart rate and corrected sinus node recovery time.

Cite This Study

Jordan et al. (1978) studied this question.

synapsesocial.com/papers/6a82dc557a209f4aae23c002https://doi.org/10.1161/01.cir.57.2.217
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Also Consider

Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context:

  1. 1Altered Autonomic Mechanisms in the Sick Sinus Syndrome and Diurnal Variations in the Parameters of Sinus Node Function : Symposium on Sinus Node Function and Its Abnormality1980 · 5 citations
  2. 2Heart rate responses to autonomic drugs in sick sinus syndrome. Correlation with syncope and electrophysiologic data.1991 · 14 citations
  3. 3Heart rate responses in patients with sinus node disease compared to controls: Physiological implications and diagnostic possibilities1980 · 17 citations
  4. 4Heart rate responses in patients with sinus node disease compared to controls: physiological implications and diagnostic possibilities1980 · 7 citations
  5. 5Comparative Study of Electrophysiological and Holter Monitoring Data in Estimating Sinoatrial Function2008 · 7 citations