LONG-TERM EFFECTS OF POSTMENOPAUSAL HORMONE REPLACEMENT THERAPY ON PULSATILITY INDEX OF INTERNAL CAROTID AND MIDDLE CEREBRAL-ARTERIES

The authors studied the long-term effects of hormone replacement thera py (HRT) on vascular resistance of internal carotid artery (ICA) and m iddle cerebral artery (MCA) in postmenopausal women. Twenty-five postm enopausal women participated in this 1-year, single-center, open study . Subjects received continuous estradiol 50 mu g/day via transdermal r oute (Estraderm TTS 50, Ciba-Geigy) with oral medroxyprogesterone acet ate 10 mg/day for 12 days every second month. Subjects, who had been s tudied previously at baseline and at 6, 8, 22, and 24 weeks, were foll owed up 48 weeks after the start of treatment, Vascular resistance of ICA and MCA was assessed by pulsatility index (PI) measured by bidirec tional Doppler ultrasonography. The significant reduction of PI from b aseline, which had been observed by 6 weeks of treatment for both ICA and MCA, reached a maximum at approximately 22 weeks of treatment (25. 3% and 24.5% reduction from baseline for ICA and MCA, respectively; p = 0.0001). Pulsatility index reductions reached after 24 weeks of trea tment were maintained to 48 weeks both for MCA and ICA. Results demons trate that in postmenopausal women, the rapid reduction of vascular re sistance in ICA and MCA induced by estradiol is long-lasting.