| Summary: | 碩士 === 慈濟大學 === 神經科學研究所 === 90 === The cardiovascular variability in patients with acute cerebrovascular accident and hypertension (CVA-HTN) was uncertain. Labetalol, a selective α1 and nonselective β1,2 adrenoceptor antagonist, has been extensively used to treat patients with acute CVA-HTN, but its effects on cardiovascular variability remained to be validated. In this study, we evaluated the cardiovascular variability in acute CVA-HTN patients with and without labetalol treatment as well as the relationship between cardiovascular variability and sympathetic activity. Power spectral analysis of both resting arterial pressure variability (APV) and heart rate variability (HRV) and baroreceptor reflex (BRR) sensitivity were conducted by a noninvasive continuous arterial pressure monitor and electrocardiogram recordings. Subjects include health volunteers, patients with hypertension without any treatment (HTN) and acute CVA-HTN with and without labetalol treatment (12.5 mg, iv). The individuals with disorders or under medications that may affect cardiovascular variability were excluded. The blood pressure appeared to increase in all patients groups. However, statistical significance was only observed between health volunteers and acute CVA-HTN. The acute CVA—HTN patients also presented a shorter RR interval. HTN patients appeared to exhibit higher very low frequency (VLF), low frequency (LF) and high frequency (HF) components of APV. In addition, HTN patients appeared to have a higher normalized LF (LF%) and low-high frequency ratio (LF/HF) of HRV. On the contrary, the BRR sensitivity appeared to decrease in the HTN patients. Acute CVA-HTN patients exhibited an increase in every frequency component of APV, LF% and LF/HF of HRV as well as a decrease in HF of HRV. Acute CVA-HTN patients also presented a decrease in BRR sensitivity. After labetalol treatment VLF of APV, LF% and LF/HF ratio of HRV as well as BRR were all decrease. Acute CVA-HTN patients showed an increase in blood pressure, cardiovascular sympathetic tone, and a decrease cardiac parasympathetic activity as compared to HTN patients. The increased sympathetic tone may be attenuated with labetalol. Our finding suggest that LF% and LF/HF of HRV can reflect of sympathetic activity in the stroke patients.
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