DSA法による肥大型心筋症の局所心筋冠血流予備能の検討

Regional myocardial coronary blood flow reserve in hypertrophic cardiomyopathy assessed by digital subtraction coronary angiography

　肥大型心筋症（HCM）では，胸痛の訴えや，ときに心筋梗塞様病変の出現などが見られ，心筋虚血の関与が注目されている。そこで，本症の局所心筋冠血流予備能（rMFR）の異常と，その局在性を明らかにするため，HCM連続18例にpapaverine（P）負荷前後でDSAを施行した。対照は健常群8例である。rMFRは中隔中部，中隔下部，心尖部，左室後壁の時間濃度曲線よりCm／Tm（Cm：peak density，Tm：Cmに達する時間）を算出し，P投与前後のCm／Tmの比として求めた。HCM群の中隔，心尖部領域のrMFRは健常群に比し有意に低下し，さらに，症例別に検討すると心尖部肥大型は心尖部で，閉塞性は中隔中部で，非閉塞性は中隔中部あるいは下部から心尖部でより強く低下した。すなわち，壁肥厚の強い領域でより高度にrMFRが低下するという局在性が明らかとなった。非対称性肥大を特徴とする本症では，心筋内冠循環動態の異常にも局在性があり，その評価にDSA法は有用な検査法と考えられた。

Previous observations suggest the presence of is-chemia in the disproportionately thickened interven-tricular septum (IVS) of patients with hypertrophic cardiomyopathy (HCM), although the details remain obscure. Utilizing digital subtraction coronary an-giography (DSA) with LAO projection before and after intracoronary papaverine (P) injection, we e-valuated regional myocardial coronary blood flow re-serve (rMFR) consecutively 18 patients with HCM, and compared it with that of 8 patients without apparent cardiac abnormality (C). Time-density curves were obtained from digital angiograms of the myocardial region of interest. We measured peak contrast density (Cm) and time to peak contrast(Tm). An index of rMFR was calculated as the quo-tient of Cm/Tm before and after P.

In HCM, rMFR in IVS and apex was significantly lower than that of C (Mid-IVS : 1.9± 0.5 vs 3.9±0.5, p＜O.001 ; Low-IVS : 2.0±0.5 vs 4.4±0.9, p＜0.001; Apex : 2.0±0.7 vs 4.5±1.6, p＜O.01). There was correlation between the impairment of rMFR and the extent of hypertrophy in HCM. In conclusion, we could state that, in HCM, the region of impaired my-ocardial coronary blood flow reserve is localized. In HCM, DSA is useful in evaluating myocardial coro-nary blood flow reserve.