書誌事項
- タイトル別名
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- Possible contribution of .ALPHA.-adrenergic abnormalities to cerebral ischemia in the patients with sinus bradycardia. Analysis by pharmacologic autonomic nervous test.
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Background : Syncope of patients with bradyarrhythmia is perceived as severe sign of low cardiac output caused by bradycardia and as a major criteria for pacemaker implantation (PMI). However, it has been reported that PMI can not always prevent syncope ; it has been suggested that not bradycardia but an abnormality of the autonomic nervous system blays a part in syncope. Purpose : To investigate the relation between autonomic nervous dysfunction and syncope in cases of sinus bradycardia (SB). Subjects : Thirty-nine patients with SB were divided into two groups according to the presence (group S, n=16, 46.9±20.0 years) or absence (group N, n=23, 40.4±17.6 years) of syncope or presyncope. Methods : Corrected sinus node recovery time (CSNRT) was measured by electrophysiologic study. Pharmacologic autonomic nervous tests were performed as follows in a quiet room. Increased HR by application of 0.04 mg/kg atropine (para-tone), and by 0.004 μg/kg/min isoproterenol divided by 0.004 (β-sens) were evaluated. β-tone was obtained by subtracting HR after application of propranolol (0.2 mg/kg) from that of atropine. Basal β-sympathetic activity was evaluated by β-sec that was obtained by β-tone/β-sens. Increased SBP by application of 0.4 μg/kg/min phenylephrine divided by 0.4 (α-sens) was evaluated. α-tone was obtained by subtracting minimum SBP after 0.2 mg/kg phentolamine from SBP after application of propranolol. Basal α-sympathetic activity was evaluated by α-sec, that was obtained by α-tone/α-sens. Result : There were no significant differences in basal clinical characteristics (age, sex, cardiac function) between the groups. The parameters of the functions of parasympathetic and β-sympathetic receptors (para-tone, β-sens, β-tone, β-sec) showed no significant differences between the groups. α-sens was attenuated (P<0.01) and α-sec was augmented (P<0.0001) significantly in group S. Conclusion : It was suggested that syncope or presyncope in SB patients could be attributed to failure of vasoconstriction mediated by α-sympathetic receptor but to severity of sinus node dysfunction. (J Nippon Med Sch 1999 ; 66 : 119-126)
収録刊行物
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- 日本医科大学雑誌
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日本医科大学雑誌 66 (2), 119-126, 1999
日本医科大学医学会