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Exercise chronotropy in patients with normal and impaired sinus node function after cardiac transplantation
G Heinz1, S Radosztics, C Kratochwill
1Department of Internal Medicine II, University of Vienna, Austria.
Pacing and Clinical Electrophysiology : PACE
|September 1, 1993
Summary
Cardiac transplant recipients with impaired sinus node (SN) function show reduced heart rate response during exercise. This impacts their chronotropic capacity, even with normalized SN function post-surgery.
Area of Science:
- Cardiology
- Exercise Physiology
- Transplantation Medicine
Background:
- Sinus node (SN) function is critical for heart rate regulation.
- Assessing chronotropic response post-cardiac transplantation is important for patient management.
- Postoperative SN dysfunction can affect exercise capacity.
Purpose of the Study:
- To investigate the chronotropic response to graded exercise in cardiac transplant recipients.
- To compare exercise heart rate response based on postoperative sinus node function.
- To evaluate the impact of sinus node recovery time on exercise capacity.
Main Methods:
- 32 cardiac transplant recipients underwent symptom-limited graded exercise testing.
- Systematic evaluation of postoperative donor sinus node (SN) function was performed.
- Patients were grouped based on normal (Group I) or impaired (Group II) SN function.
Main Results:
- Group II patients (impaired SN function) had lower basal and peak exercise heart rates compared to Group I.
- Chronotropic response was significantly lower across all exercise stages in Group II.
- Fewer patients in Group II achieved a peak heart rate >= 120 beats/min.
Conclusions:
- Cardiac transplant recipients with postoperative sinus node deficiency exhibit reduced chronotropy during rest and exercise.
- Impaired sinus node function impacts the heart rate's ability to increase with exertion.
- Despite apparent functional normalization, underlying SN deficiency affects exercise performance.