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Effect of coronary bypass grafting on autonomic cardiovascular reflexes
1Social Insurance Institution, Rehabilitation Services, Turku, Finland.
Insights
Coronary artery bypass grafting (CABG) slightly reduced heart rate responses in cardiovascular reflex tests. However, blood pressure and pupillometry remained unaffected, suggesting minimal clinical impact on the autonomic nervous system.
Area of Science:
- Cardiovascular Physiology
- Autonomic Nervous System Function
- Surgical Outcomes
Background:
- Coronary artery disease (CAD) necessitates interventions like coronary artery bypass grafting (CABG).
- The impact of CABG on autonomic nervous system (ANS) function, particularly cardiovascular reflexes, requires detailed investigation.
- Understanding these effects is crucial for assessing patient recovery and long-term cardiovascular health.
Purpose of the Study:
- To evaluate the effects of CABG on standard cardiovascular reflex tests.
- To assess changes in pupillometry following CABG.
- To determine the level at which autonomic dysfunction occurs post-CABG.
Main Methods:
- Studied 15 patients with CAD undergoing CABG without prior myocardial infarction.
- Assessed heart rate and blood pressure responses using deep breathing tests and the Valsalva maneuver.
- Utilized beat-to-beat blood pressure monitoring (Finapres) and pupillometry.
Main Results:
- Heart rate responses to deep breathing and Valsalva maneuver were attenuated post-CABG.
- Beat-to-beat blood pressure responses and pupillometric variables showed no significant changes after CABG.
- Diminished heart rate responses generally remained within age-related normal ranges.
Conclusions:
- Attenuation of heart rate responses is likely due to localized perioperative damage to effector organs or autonomic nerves.
- No significant dysfunction was observed at the baroreceptor or central cranial autonomic nervous system levels.
- The clinical significance of CABG-induced autonomic nervous system changes appears minimal due to preserved blood pressure regulation and heart rate variability.
Abstract:
The effect of coronary artery bypass grafting (CABG) on standard cardiovascular reflex tests and pupillometry was studied in 15 patients with coronary artery disease without previous myocardial infarction. The heart rate responses to the deep breathing test and to the Valsalva manoeuvre were attenuated after CABG, whereas CABG had no effect on the beat-to-beat measured blood pressure responses (Finapres) or the pupillometric variables. Although the heart rate responses diminished in almost all of the patients after CABG, the values, however, remained in most cases within the age-related normal range. It is concluded that the attenuation of heart rate responses after CABG is due to perioperative local damage on the effector organ or autonomic nerves rather than due to dysfunction on the baroreceptor level or in cranial level of the autonomic nervous system. Because the blood pressure responses were not affected by CABG and the heart rate responses after CABG mainly remained within the normal range indicating sufficient parasynthetic activity, it is probable that the clinical significance of the effects of CABG on the autonomic nervous system is not very important.