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PR interval adaptation in the denervated transplanted heart
J Koller-Strametz1, C Kratochwill, M Grabenwöger
1Department of Cardiology, University of Vienna, Austria.
Pacing and Clinical Electrophysiology : PACE
|May 1, 1997
Summary
Heart transplant recipients show PR interval adaptation during exercise, similar to innervated hearts. Circulating norepinephrine influences this response, which appears age-related.
Area of Science:
- Cardiology
- Transplantation Medicine
- Exercise Physiology
Background:
- Heart transplantation results in cardiac denervation, impacting autonomic regulation.
- The PR interval, reflecting atrioventricular nodal conduction, is a key electrophysiological parameter.
- Understanding exercise response in transplanted hearts is crucial for patient management.
Purpose of the Study:
- To investigate the dynamic PR interval response to exercise in heart transplant recipients.
- To explore the relationship between heart rate, PR interval, and norepinephrine levels during exercise.
- To assess the influence of recipient and donor age on exercise-induced PR interval changes.
Main Methods:
- 21 heart transplant recipients underwent standardized treadmill exercise.
- Heart rate (HR) and PR interval were measured at rest and during incremental exercise.
- Norepinephrine (NE) levels were assessed at rest and peak exercise in 17 participants.
Main Results:
- The PR interval shortened during exercise, with an average decrease of 3.4 ms per 10 bpm HR increase.
- A linear relationship was observed between HR and PR interval (P=0.0001).
- Circulating NE levels increased significantly with exercise, correlating with PR interval shortening; blunted NE response led to minimal PR changes.
Conclusions:
- The denervated transplanted heart demonstrates exercise-induced PR interval adaptation.
- The HR-PR relationship in transplanted hearts resembles that of innervated hearts.
- Exercise-induced PR interval changes are influenced by circulating NE and appear age-dependent.