水利尿薬，トルバプタンの追加投与で低Na血症と低心拍出量状態から脱し，独歩退院と在宅療法が可能となった難治性心不全の1例

New Aquaretics:An Elderly Man Avoided Intractable Heart Failure,Repetitive Hyponatremia,Systemic Congestion,Low Cardiac Output and Orthostatic Hypotension through the use of Torvaptan,which led to Improved Quality of Life(QOL)and made Home Ambulatory Treatment Possible

要旨　患者は74歳，男性．拡張型心筋症．うっ血と低心拍出量状態(LOS)が混在する難治性心不全に対し，心臓再同期療法に加え静注強心薬とNa(ナトリウム)利尿薬を併用投与しても改善が得られなかった．特に，うっ血解除の過程で低Na血症と血管内脱水を容易に来し，LOSと起立性低血圧が顕在化した．そこへトルバプタン投与とフロセミド減量を行ったところ，1日尿量は同程度に維持され，上昇したBUN/Cr比と低Na血症が改善，起立性低血圧が消失した．体重は軽度増加したが，肺うっ血は来さず，むしろ胸水や浮腫は減少して独歩退院と在宅療法が可能となった．

　水利尿により血漿浸透圧が正常化し，細胞内外の過剰水の移動により十分な循環血漿量が保持された結果と考えられた．トルバプタンは低Na血症を改善するばかりでなく，過剰水の循環血漿内への移動を促すと思われる．LOS患者であっても安定した血行動態の下に効果的なうっ血解除が可能な水利尿薬である．

　A 74 year-old-male patient with dilated cardiomyopathy consequently suffered from intractable hyponatremia, systemic congestion, low cardiac output syndrome(LOS)and orthostatic hypotension in spite of the intensive use of intravenous inotropic and diuretic agents after cardiac resynchronization. In particular, in the process to avoid congestion, he experienced hyponatremia and intravascular dehydration many times, and finally he fell into LOS and serious orthostatic hypotension. Because of this, we administrated Tolvaptan and reduced the amount of furosemide. Then, although daily urine volume was maintained at the same level, the BUN/Cr ratio decreased, the serum Na level improved, and systemic congestion and orthostatic hypotension dramatically disappeared. Body weight mildly increased, but pulmonary edema and pleural effusion did not occur. With the help of cardiac rehabilitation, he recovered his QOL and home ambulatory treatment became possible.

　Normalization of plasma osmolality seemed to produce a sufficient volume of circulating plasma by moving excess water from the intracellular and thoracic cavity into the plasma. Tolvaptan not only improved hyponatremia,but also moved the excess water into the circulating plasma. This new aquaretics seems to relieve LOS patient from intractable congestion effectively under relatively stable hemodynamics.