心外膜炎，心筋炎を契機に出現した起立性低血圧症の1例

A Case of Orthostatic Hypotension after Pericarditis and Myocarditis

　患者は70歳，女性．全身倦怠感を主訴に来院した．心エコー図およびMRIで心嚢液の貯留を認め，Gd-DTPA造影MRIで左室心筋に強い造影効果を認めた．心嚢穿刺で炎症性心嚢液を認め，他の諸検査の結果より，心外膜炎，心筋炎と診断した．心嚢穿刺後，全身倦怠感は速やかに改善した．しかし，その後から起立性低血圧症状が出現するようになった．自律神経機能検査で交感神経求心路，迷走神経遠心路，交感神経遠心路心臓枝の異常が認められた．α・β作動性交感神経機能検査で副交感神経緊張度，β交感神経緊張度の著明な低上下が認められ，心臓に分布する自律神経の異常が示唆された．また，¹²³I-MIBG心筋シンチグラフィで著明な取り込み低下とwashoutの亢進を認めた．心外膜炎，心筋炎による心臓交感神経障害が著明な起立性低血圧の出現に関与していると考えられた．

A 70-year-old woman was admitted with the symp-tom of general fatigue. She was diagnosed, by echocar-diography. MRI and laboratory findings, as having pericarditis and myocarditis. After drainage of pericar-dial effusion, her general condition soon improved, but the symptom of orthostatic hypotension was observed. During physical examination, her systolic blood pres-sure fell from 178 to 98 mmHg on standing. We carried out an autonomic function test. Her responses to postur-al head-up tilt test and Valsalva maneuver were abnor-mal. Blood pressure responses to hyperventilation test, cold presser test and phenylephrine test were normal. These data indicated that the vasomotor center, efferent sympathetic fibers and α-receptor were intact and auto-nomic dysfunction seemed to be due to afferent auto-nomic fibers, efferent vagal fibers or cardiac efferent adrenergic fibers. We also examined α and β sympa-thetic nervous tone. and α and β receptor sensitivity. These data also indicated that βsympathetic nerve tone was decreased and β receptor sensitivity was upgraded. All data strongly suggested that autonomic dysfunction in this patient was due to cardiac sympathetic system failure. In fact. by using ¹²³I-MIBG cardiac scintigraphy. it was shown that her heart had broad sympathetic nerve denervation. These findings indicated that cardiac sympathetic nerve denervation after pericarditis and myocarditis could account for at least a part of the pathogenesis of orthostatic hypotension in this patient.