Real-time heart rate variability and its correlation with plasma catecholamines during laparoscopic adrenal pheochromocytoma surgery

BACKGROUND: We studied sympathovagal activity using real-time heart rate variability (HRV) and determined its relationship with plasma catecholamines to characterize short-term cardioregulatory mechanisms during laparoscopic adrenal pheochromocytoma surgery. METHODS: We recruited 20 patients with pheochromocytoma (Group P) and 20 with incidentaloma.(Group I). HRV, systolic blood pressure and heart rate were continuously monitored. The low frequency and high frequency spectra denoted, respectively, sympathetic and parasympathetic activity. The low frequency/high frequency (LF/HF) ratio represented sympathovagal balance. Blood samples for epinephrine and norepinephrine assays were collected before, during, and after surgery. After log transformation of the repeated measures, a linear regression model was applied on their mean values. The correlation coefficients among variables were calculated using the Spearman rank test. RESULTS: No significant changes were observed in Group I. In Group P, epinephrine and norepinephrine increased in all patients during peritoneal insufflation and tumor resection. In 16 patients, systolic blood pressure, heart rate, low frequency, and LF/HF ratio increased concurrently. In four patients, low frequency and LF/HF ratio decreased. Three of these patients had normal systolic blood pressure and heart rate, and the fourth patient had hypotension and tachycardia. The high frequency component was enhanced in 15 patients and was stable in five. Low frequency was correlated with norepinephrine (r = 0.68, P < 0.001), systolic blood pressure (r = 0.66, P < 0.01), and heart rate (r = 0.62, P < 0.05). CONCLUSION: This study demonstrated a strong correlation between low frequency HRV, plasma norepinephrine, arterial blood pressure, and heart rate during pheochromocytoma surgery.