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Heart Rate Turbulence Analysis in Subclinical Hypothroidism Heart Rate Turbulence in Hypothyroidism

摘要:
Background: Heart rate turbulence (HRT) is a baroreflex-mediated biphasic reaction of heart rate in response topremature ventricular beats. Abnormal HRT identifies patients with autonomic dysfunction or impaired baroreflexsensitivity. The aim of the present study was to demonstrate the effect of subclinical hypothyroidism (SCH) oncardiac autonomic function using HRT parameters.
 
Methods: The study sample consisted of 25 patients (10 men, 15womenwith a mean age of 39.7  15.5 years)whowere diagnosed with SCH and 35 euthyroid patients (13 males,22 females with a mean age 38.4  11.7 years). All patients underwent 24 h ambulatory electrocardiography monitorization. The study calculated two HRT parameters, turbulence slope (TS) and turbulence onset (TO), and these HRT parameters were compared between the groups to examine the relationship between HRT and thyroid-stimulating hormone (TSH) levels.
Results: The characteristics of SCH patients and control cases were similar with regard to age, sex except for TSH levels. Serum TSH levels were significantly higher in SCH patients than in the controls (7.3  1.8 IU/ml vs. 2.4  1.0 IU/ml, p < 0.001). TO was significantly higher in SCH patients compared with controls (-1.51  0.5 vs. -2.2  1.0, p = 0.002). SCH patients had lower TS values than controls (7.6  2.4 vs. 10.8  3.4, p < 0.001). TO was positively correlated with serum TSH levels (r = 0.276, p = 0.033). There was also a negative correlation between TS and serum TSH levels (r = -0.437, p < 0.001).
Conclusions: The results of our study indicated that cardiac autonomic function is impaired in patients with SCH.