Quantitative Evaluation of Cardiac Parasympathetic Activity in Normal and Diabetic Man

Abstract

Heart rate and RR variation (the standard deviation of the mean RR interval for a 5-min period) were evaluated as measurements of cardiac parasympathetic nervous system activity in fasting supine diabetic (N = 22) and comparable age normal (N = 22) subjects. The rate of breathing did not effect heart rate, but was inversely related to the RR variation (r = 0.89, P less than 0.01). Heart rate was increased (P less than 0.0001) and RR variation decreased (P less than 0.05) during beta-adrenergic stimulation with isoproterenol and during parasympathetic blockade with atropine (both P less than 0.0001). Hence, the cardiac effects of beta-adrenergic stimulation may mimic the effects of diminished parasympathetic function. To evaluate parasympathetic control of RR variation, independently of possible effects of increased sympathetic activities, studies were performed during beta-adrenergic blockade with propranolol. RR variation during propranolol was less both in 14 diabetic subjects without clinical symptoms of autonomic neuropathy (P less than 0.005) and in 8 diabetics with clinical symptoms of autonomic neuropathy (P less than 0.001) when compared with 22 age-comparable normal subjects. The measurement of RR variation was very reproducible with a day-to-day coefficient of variation of 9.7 +/- 2.8% (x +/- SEM) in diabetic subjects with stable hyperglycemia. It is concluded that supine RR variation during a deep respiratory rate and during beta-adrenergic blockade is a sensitive, quantitative, and reproducible method to evaluate parasympathetic nervous activity in normal and diabetic subjects. Furthermore, cardiac parasympathetic activity may be diminished in diabetic subjects before clinical symptoms of autonomic neuropathy are evident.

Heart rate variability: a review

“…The decreased beat-to-beat variability during deep breathing in diabetic neuropathy was first reported by Wheeler and Watkins [139] and confirmed by many others [92]. In studies comparing cardiac autonomic function tests and HRV indices (based on both short (5-min) and 24-h ECG recordings), show that, in diabetic patients without abnormal function tests, HRV was lowered [92].…”

“…In studies comparing cardiac autonomic function tests and HRV indices (based on both short (5-min) and 24-h ECG recordings), show that, in diabetic patients without abnormal function tests, HRV was lowered [92]. It was concluded that cardiac (parasympathetic) autonomic activity was diminished in diabetic patients before clinical symptoms of neuropathy become evident [92,119,134].…”

Autonomic dysfunction in primary biliary cirrhosis correlates with fatigue severity

“…E-I ratio was derived from maximum divided by minimum RR intervals [45]. Additionally, RR intervals were converted to instantaneous heart rates, which allowed calculation of the absolute change in heart rate from inspiration to expiration, the E-I difference.…”

Decreased heart rate variability may predict the progression of carotid atherosclerosis in type 2 diabetes

“…A low LF HRV may predict the progression of atherosclerosis in these patients. thetic innervation, whereas high frequency (HF) (0.15-0.40 Hz) oscillations indicate parasympathetic activity [1,29,34,37,38]. Reduced HRV is a feature of autonomic neuropathy.…”