異型狭心症発作時のST-T部電気的交互脈と心室性不整脈の関係

Relationship between electrical alternans of ST-T segment and ventricular arrythmia during episodes of ST segment elevation in patients with variant angina

　心電図ST-T部の電気的交互脈（ST-T segment eiec—trical alternans以下STEAと略す）は，動物実験では急性心筋虚血時に発現することが以前から報告^1〜4）されているが，臨床的には比較的新しく，1974年Williamsら^5）によって異型狭心症発作時に発現すると報告されたのが最初である。

　異型狭心症の発作時，心室不整脈（Ventricular Ar—rhythmia以下VAと略す）をしばしば認めるが，STEAとVAの関係について検討した報告は極めて少なく，Kleinfeld ＆ Rozanski （1977年）^6），Rozanski ＆ Kleinfeld（1982年）^7）の2編に過ぎない。彼らは，STEAがVAを伴い易く，そのVAは重篤なものが多いと述べているが，VAの質的解析を充分に行なっていない。そこで我々は，異型狭心症発作時のSTEAとVAの関係を量的に検討するだけでなく，質的にも検討した。

Relationship between ventricular arrhythmias (VA) and electrical alternans of ST-T segment (STEA) during episodes of ST elevation was examined in 18 patients with variant angina. Eight of 18 patients (41%) showed STEA during episodes of ST elevation, while 10 (56%) showed no STEA. Of 93 episodes in 18 patients, STEA was observed in 19 episodes (20%), while no STEA was seen in other 74. VA occurred in 14 of 19 episodes (74%) with STEA, while VA occurred in only 21 of 74 episodes (28%) without STEA.

VA during STEA had the following characteris-tics. 1) Bigeminy and ventricular tachycardia occur-red frequently. 2) Most of the VA occurred during increasing ST elevation period (occlusive dysrhy-thmias). 3) Coupling index of single premature ventricular contraction was more longer than those of ventricular tachycardia. 4) STEA and VA were rather observed in patients without angiographically significant coronary stenosis. 5) An injury current might be regarded as a mechanism of VA during STEA because of a characteristic relation between STEA and VA.