運動負荷試験による拡張型心筋症（DCM）に対する塩酸ブナゾシンの慢性効果の判定

Exercise testing of the chronic effects of Bunazosin hydrochloride on dilated cardiomyopathy

　慢性心不全患者の予後を規定する因子として不整脈や安静時の心機能が重要とされていた。しかし，近年，心不全患者の重症度の評価や治療の決定・治療効果の判定に運動負荷試験による運動耐容能の評価がクローズアップされている。

　一方，塩酸Bunazosin（Bunazosin hydrochloride）は，我が国で開発されたpostsynaptic　α-receptor （α₁-receptor）を選択的に阻害するα-遮断剤である。本剤の慢性心不全に対する有効性はいくつかの施設で報告されているが，いずれも急性効果であり^1〜4），長期間の投与による慢性効果についての検討は少ない^2）。

Bunazosin hydrochloride was administrated in 3-mg oral doses to the 10 patients (6 males and 4 females, average 49.9 years) with dilated cardiomyo-pathy (DCM) of class II in the NYHA functional classification. Then we observed the changes in their hemodynamics at rest, chest X-ray, echocar-diography, humoral factors and symptom-limited exercise tolerance with treadmill testing before treatment and 4 and 8 weeks after administration. All but the left ventricular end-diastolic diameter after 8 weeks were unchanged. Of the humoral factors, only aldosterone decreased significantly during the treatment. On the other hand, the duration of symptom-limited exercise was prolonged significant-ly, and for a given exercise load, a reduction of heart rate and systolic blood pressure as well as adrop in the PRP occurred at 8 weeks after admini-stration. Therefore, bunazosin appears to improve cardiac function and exercise tolerance in the pa-tients with DCM, at dosages which do not affect hemodynamics at rest.