Temporary loss of cardiac autonomic innervation after the maze procedure

Abstract

Blunted sinus node response to exercise has been reported after the maze operation. We suggested the autonomic vegetative function of the heart to be disturbed after the maze procedure. 17 patients, mean age 63 +/- 15 years, with chronic atrial fibrillation for 49 +/- 46 months (range 5-65) underwent the maze procedure during mitral valve surgery. Bicycle stress test, 24-h electrocardiography and heart rate variability were analysed in 11 patients after three and in six after 14 +/- 3 months. Spectral analysis within two frequency bands, vector analysis of the main circular resultant and influence of orthostasis and Valsalva manoeuvre on different R-R intervals were calculated. One patient died from a perioperative ischaemic stroke. At follow-up, all patients were in sinus rhythm. Heart rate reached 84 +/- 14%, the mean circular resultant was 60 +/- 48%, the ratio of the longest to the shortest R-R interval during the Valsalva manoeuvre was 92 +/- 8% and the ratio of maximal to minimal R-R interval after orthostasis was 98 +/- 4% of the age-adjusted normal value. Maximal workload was 116 +/- 31 watts. All patients had abnormal heart rate variability. Heart rate variability was significantly more blunted after three months, than after 14 months (P < 0.05). The minimal heart rate and the difference between the maximal and the minimal heart rate during the 24-h electrocardiography were significantly correlated to the number of normal physiological tests (r = -0.52; P < 0.05; r = 0.71; P < 0.005); for the maximal heart rate, there was a positive trend only (r = 0.44; P = 0.07). Early after the maze procedure, a nearly total denervation of the sinus node is present, similar as seen after heart transplantation, with partial restoration of the autonomic function after one year. The exercise capacity of the patients was satisfactory.