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Updated: Jun 4, 2025
06:40
Impact of Intracardiac Neurons on Cardiac Electrophysiology and Arrhythmogenesis in an Ex Vivo Langendorff System
Published on: May 22, 2018
10.6K
Cardiac Presynaptic Sympathetic Nervous Function Evaluated by Cardiac PET in Patients with Chronotropic Incompetence
Toshihiko Goto1, Shohei Kikuchi2, Yomei Sakurai2
1Department of Cardiology, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan; t-goto@med.nagoya-cu.ac.jp.
Summary
Chronotropic incompetence (CTI) involves impaired heart rate response during exercise. This study found higher hydroxyephedrine retention in CTI patients, suggesting presynaptic sympathetic nerve dysfunction contributes to this condition.
Area of Science:
- Cardiology
- Nuclear Medicine
- Neuroscience
Background:
- Chronotropic incompetence (CTI) limits exercise capacity and predicts mortality.
- Previous research indicated postsynaptic sympathetic dysfunction in CTI patients without heart failure (HF).
- Cardiac presynaptic sympathetic nervous system function in CTI remains poorly understood.
Purpose of the Study:
- To investigate cardiac presynaptic sympathetic nervous system function in patients with CTI but no HF.
- Utilized 11C-hydroxyephedrine Positron Emission Tomography (PET) to assess presynaptic function.
Main Methods:
- Cardiac PET with 11C-hydroxyephedrine was performed on 13 CTI patients and 9 healthy controls.
- Measured the global hydroxyephedrine retention index, reflecting presynaptic sympathetic activity.
- CTI was defined as failing to achieve 80% of heart rate reserve during exercise.
Main Results:
- No significant differences in clinical or echocardiographic parameters between groups.
- CTI patients exhibited significantly lower peak heart rates compared to controls.
- A significantly higher global hydroxyephedrine retention index was observed in CTI patients.
Conclusions:
- Patients with CTI without HF show elevated hydroxyephedrine retention.
- Impaired norepinephrine release from presynaptic sympathetic nerves is a potential mechanism underlying CTI.
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