慢性虚血心におよぼす冠動脈造影の影響—イオン性造影剤と非イオン性造影剤の比較検討

Comparative effects of ionic and nonionic contrast materials on chronic ischemic myocardium in dogs

　冠動脈疾患患者の診断，治療方針の決定に選択的冠動脈造影が必須の検査として広く用いられている。しかし同検査には，0.1％前後の重篤な合併症がある^1）。それらのうち危険な不整脈や血行動態の増悪は，造影剤自体がもつ心筋に対する直接的な作用に起因するものであり，造影剤のhypcrosmolalityやhyperviscosityなどの物理化学的特性，ヨード基を含む陰イオン基の化学毒性，造影剤に大量に含まれるNa^＋イオンやEDTAなどの添加剤などが原因の主たるものと考えられている^2〜9）。

　このため近年，より低張なdimericなイオン性造影剤（Sodium methylglucamine ioxaglatc；Hexabrix®他）や，非イオン性造影剤（Metrizamide；Amipaque®，Iopamidol他）などが開発され，従来のmonomericなイオン性造影剤（Sodium methy191ucamine diatrizoate；Urografin 76®以下Diatrizoateなど）に変わって臨床例でも応用されるようになってきた^10〜15）。今回著者らは，現在最も広く用いられているイオン性造影剤Dia—trizoateおよび非イオン性造影剤MetrizamideならびにIopamidolを用いて，慢性心筋梗塞犬の選択的冠動脈造影を行い，局所心筋動態と左室血行動態におよぼすこれらの造影剤の影響を比較検討した。

The myocardial depressant effects of ionated contrast materials have long been recognized. The approaches to alleviating the myocardial toxicity of contrast materials have developed contrast ma-terials devoid of sodium and other single valence cations. This study was designed to demonstrate the usefulness of nonionic contrast materials in comparison to ionic contrast materials.

Experiments were performed seven to ten days after coronary occlusion in eleven closed-chested dogs preinstrumented with ultrasonic dimension gauges for measurement of segment length in (1) non-ischemic zone (NIZ), (2) border zone (BZ), and (3) ischemic zone (IZ). Left ventricular pressure was measured by high fidelity catheter-tip manometer introduced from the right femoral artery. The follow-ing solutions (6 ml/2 seconds each) were injected fluoroscopically into the left main coronary artery in random order: (a) diatrizoate (Urografin76^R), (b) metrizamide (Amipaque^R), (c) iopamidol.

Following diatrizoate injection, peak positive and peak negative dp/dt were decreased and lasted six to fifteen seconds. In NIZ and BZ, diatrizoate caused the decrease in systolic shortening from 19.0% to 15.2% (p<0.01) and 5.9% to 4.4% (p<0.01), respectively. Whereas end-diastolic len-gth increased to 102±1% of control value in both NIZ and BZ. In contrast to the findings in NIZ and BZ, paradoxical movement lessened slightly but significantly (p<0.05) in IZ. Thus, diatri-zoate has the different effects on the myocardium in IZ from that in NIZ or BZ. Injection of metrizamide or iopamidol produced minimal changes in both positive and negative dp/dt, systolic shortening and end-diastolic length in all zones (p<0.1).

A clear superiority in hemodynamics of nonionic contrast materials over ionic contrast materials for coronary arteriography is revealed.