Effect of antihypertensive drug therapy on short-term heart rate variability in newly diagnosed essential hypertension.
1. Abnormalities of cardiac autonomic regulation are a potential mechanism for morbidity despite blood pressure (BP) lowering in hypertension. Analysis of short-term (5 min) heart rate variability (HRV) provides a non-invasive probe of autonomic regulation of sino-atrial (SA) node automaticity. 2. We hypothesized that antihypertensive drug therapy would be associated with an increase in 5 min overall HRV, along with a decrease in blood pressure (BP), at 8 weeks follow up in subjects with newly diagnosed, never-treated essential hypertension. 3. One hundred and fifty patients (84 men and 66 women; mean (+/-SD) age 48 +/- 10 years) with newly diagnosed essential hypertension were divided to five groups of 30 patients each to receive one of the following antihypertensive drugs (or drug combinations): 5 mg/day amlodipine; 50 mg/day atenolol; 5 mg/day enalapril; 25 mg/day hydrochlorothiazide; or a combination of 5 mg/day amlodipine and 50 mg/day atenolol. 4. The only significant change in HRV indices was an increase in total variability of RR intervals and an increase in high-frequency (HF) RR interval spectral power in the amlodipine + atenolol-treated group (P < 0.05). 5. The results indicate that there is a dissociation between changes in short-term HRV and mean RR interval and BP lowering in patients with newly diagnosed hypertension. 6. We interpret the increase in HF RR interval spectral power in the amlodipine + atenolol-treated group as being due to an increase in vagal modulation of RR intervals and/or diminution in sympathetic restraint of respiratory sinus arrhythmia.
Pavithran
Purushothaman
P
Department of Physiology, Jawaharlal Institute of Postgraduate Medical Education and Research, Pondicherry, India. pavithranpp@gmail.com
Prakash
E Sankaranarayanan
ES
Dutta
Tarun K
TK
Madanmohan
Trakroo
T
D000328:Adult; D017311:Amlodipine / Q000008:administration & dosage; D000959:Antihypertensive Agents / Q000008:administration & dosage*; D001146:Arrhythmia, Sinus / Q000188:drug therapy; D001262:Atenolol / Q000008:administration & dosage; D004656:Enalapril / Q000008:administration & dosage; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D006852:Hydrochlorothiazide / Q000008:administration & dosage; D006973:Hypertension / Q000188:drug therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D012849:Sinoatrial Node / Q000187:drug effects* / Q000503:physiopathology
D000959:Antihypertensive Agents; D006852:Hydrochlorothiazide; D017311:Amlodipine; D001262:Atenolol; D004656:Enalapril