Effect of coronary bypass grafting on autonomic cardiovascular reflexes.

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.