異型狭心症発作時のST,T交互脈に関する臨床的および実験的検討

Clinical and Experimental Studies on Electrical Alternans of ST-segment and T-wave in Variant Form of Angina Pectoris

　電気的交互脈は比較的稀な心電図異常と言われ，P波^1），QRS波^2,3），ST部^4〜7）およびT波^8）にそれぞれ単独あるいは組み合された状態で出現する^5）。とくにST部およびT波の交互脈は^13）動物実験ではしばしば認められるものの，臨床的にはきわめて稀な現象とされている^5）。

　異型狭心症発作時ST,Tの交互脈に関しては，本邦では未だ報告はなく，諸外国においてもWilliamsら^6），およびKleinfeldら^7）によるわずか2編をみるに過ぎず，その臨床的意義およびメカニズムは，今なお明らかでない。

Electrical alternans of the elevated ST-segment and T-wave was observed in two cases during an episode of a variant form of angina pectoris. In order to clarify its mechanism, experiments were carried out using 14 dogs. The electrical alternans was produced in relation to hypoxemia, hypercapnia, acidosis and premature contraction.

The clinical characteristics of these two patients were as follows;1) they had typical attacks of angina at rest for several years that increased in frequency as often as ten times per day. 2) Electrocardio-graphycally, the ischemic area was supposed to be widespread during typical attacks of angina; the elevations of ST-segment were found in I, II, III, aV_F and V₁-V₅. 3) During attacks, electrical alternans of ST-segment and T-wave occured and sometimes the T wave was inverted in alternate beats.