Objective: Removal of accessory fibres coming from the sub-stellar thoracic chain to the heart during infra-stellate surgical upper thoracic sympathectomy (ISS) may be responsible for a decreased heart rate to workload relationship during exercise following surgery. We hypothesised that heart rate would decrease not only following right ISS.
Methods: We performed repeated bicycle incremental exercise tests in 11 control subjects (26.9+/-9.5 years, 61.4+/-12.4 kg, 167+/-10 cm), and 11 patients (29.8+/-10 years, 59.3+/-12.0 kg, 168+/-7 cm) referred for bilateral ISS: results are mean+/-standard deviation. Surgery was performed at two distinct times allowing to study the consequences of unilateral and bilateral sympathectomy to confirm whether a significant relative bradycardia was constant and dependent on the operated side.
Results: For control subjects, test durations were 13.55+/-3.29, 14.09+/-4.01 and 13.00+/-3.26 min and heart rates were 187+/-7, 187+/-8 and 186+/-7 beats min(-1) at the first, second and third test, respectively. Although time to exhaustion was comparable to controls and unchanged between tests: 12.32+/-2.87, 12.3+/-2.90, 12.33+/-3.76 min, heart rate at maximum exercise decreased significantly from 176+/-16 to 164+/-15, and 148+/-15 beats min(-1), before, following unilateral and bilateral ISS, respectively. The operated side did not allow for the prediction of the effect of unilateral sympathectomy.
Conclusions: Patients should be informed of the exercise bradycardia resulting from ISS, although clinical tolerance seems excellent in endurance exercise. Contrary to previous reports at rest, during exercise no right-sided dominance was observed. These findings are consistent with reports of random distribution of sub-stellate cardiac fibres from anatomical studies.