圧負荷および容量負荷で生じた左心室肥大心の安静時および運動負荷時の左心機能

Cardiac function in stable left ventricular hypertrophy induced by pressure and volume overloading

　心筋の肥大は慢性的に心筋に加わる負荷に対応する適応現象として生ずるが^1,2），われわれは圧負荷で生じた左心室肥大心の安定期における心機能について検索を行って来た^3,4）。安静時およびカテコールアミン投与による薬剤負荷時でも心筋のポンプ機能および心筋収縮力は低下を示さず，心筋の予備力も十分に保持されていることを報告して来た^3,4）。

　しかし，圧負荷ないし容量負荷で生じた肥大心について，安静時と生理的負荷である意識下での運動負荷によってその心機能にいかなる影響が生ずるか不明瞭な点が多い。

We have compared cardiac function and myo-cardial metabolism in stable canine left ven-tricular hypertrophy (LVH), which was produced by pressure overloading (aortic banding) and volume overloading (bilateral femoral A-V fistula), with those of the normal heart (N) at rest and with exercise until exhausion.

Indices of LV function (cardiac output, stroke volume, minute work, stroke work, peak LV dp/ dt-to-isovolumic pressure) were in the normal or above normal range at rest in LVH. With exercise, these indices increased in N and pressure-overloaded hearts similarly, but the increments in function in volume-overloaded hearts were not significantly elevated. Cardiac O₂ extraction was maximal at rest in LVH increased by either pressure or volume overloading and did not increase with exercise as in N, suggesting that the hypertrophied ventricle meets the increased O₂ demands of exercise only by increasing coronary blood flow.