狭心症，糖尿病，高血圧症における拡張期心機能評価—逆方向法RI angiocardiographyによる検討

Impaired left ventricular diastolic filling in patients with angina pectoris,diabetes mellitus and essential hypertension:Assessment with backward method of ECG-gated equilibrium radionuclide angiocardiography

　近年，虚血性心疾患の左室心機能を評価するに際して，収縮期特性に比し拡張期特性の早期障害性が報告され^1〜4），拡張期心機能評価の重要性が認められてきた。しかし，いまだ局所壁運動異常を認めない疾患についての報告は少ない^2）。

　心筋の虚血状態は，酸素供給と酸素需要の相対的あるいは絶対的なアンバランスにより生じるものであり，主として，心筋線維への酸素供給の低下によりもたらされるものである。酸素供給の低下の要因には，冠動脈における血流量の低下^5），　microcirculationの障害^6〜8），毛細血管と心筋線維の間におけるdiffusion distanceの延長^5），そして血腋酸素濃度の低下があげられる^5）。さらに実際の虚血性心疾患においては，上記の病態の他に心臓の過剰労働による酸素需要の増大などの病態が複雑に絡みあっているものと考えられる^5）。そこで，虚血性心疾患の左室心機能評価を行う場合には，上記の諸種病態を考慮に入れる必要がある。

In order to evaluate left ventricular (LV) early diastolic filling and LV late diastolic filling, Phase 1 max and Phase 3 max were analyzed by means of the backward method of ECG-gated equilibrium radionuclide angiocardiography in 46 patients with angina pectoris (AP, with neither diabetes mellitus nor hypertension, 5), diabetes mellitus (DM, with neither AP nor hypertension, 8), essential hyper-tension (HT, with neither AP nor DM, 23) and 10 normal subjects (Control).

The indices were determined as follows ; LV diastolic period was subdivided into the 3 equal time interval to assess LV diastolic performance in detail. Early and late 1/3 of the diastolic period were named as Phase 1 and Phase 3, respectively. Then Phase max was defined as maximum dv/dt in a Phase divided by end-diastolic counts. Phase max of Phase 1 and Phase 3 were named as Phase 1 max and Phase 3 max, respectively.

Phase 1 max was significantly reduced in the AP group, the DM group, and the HT group, but Phase 3 max was significantly increased in the AP group and the HT group when they were compared to the Control group. EF was not significantly changed in each group. Furthermore Phase 1 max was well correlated with interventricular septal thickness (IVST) (r=-0.65) which was measured using echocardiography, but was also reduced in the hypertensive patients with normal wall thick-ness (IVST≦10 min).

In conclusion these findings indicated that, (1) LV early diastolic filling was significantly impaired in the AP group, the DM group, and the HT group, but was well compensated by enhanced atrial con-traction in the AP group and the HT group, (2) furthermore I.V wall thickening was not a primary, but a important factor in determining diastolic performance in hypertensive heart disease. In addi-tion the usefullness of Phase max was stressed to as-sess LN diastolic function.