特発性心室頻拍における持続型心室頻拍と非持続型心室頻拍との比較検討

Idiopathic Ventricular Tachycardia:Comparison between Sustained Type and Non-sustained Type

　心室頻拍は心疾患に伴う非常に重篤な頻拍性不整脈として知られているが，その中には基礎心疾患と考えられるものを有しない特発性心室頻拍と呼ばれる一群の心室頻拍が最近注目されている^1〜3,12）。この特発性心室頻拍は基礎となる心疾患を有しない比較的若い年齢層にみられ，その自然予後は一般に良好であると考えられている^4,5）。しかしながら本症には時に頻拍中に心不全の発生が認められることもあり^6），また稀ではあるが本症による突然死の発生も認められることが報告されており^7），その明らかな病態に関してはいまだに不明な点が多い。

　今回我々は特発性心室頻拍と考えられる25例を経験し，その臨床的特徴並びに心臓電気生理学的特徴につき，持続型と非持続型に分け比較検討を行った。本症における持続型と非持続型との比較検討に関しては，著者らが調べた範囲ではその詳細な検討の報告はいまだなく，我々の検討は特発性心室頻拍の臨床的・心臓電気生理学特徴並びにその自然予後を考える上で参考になると考え報告する。

Twenty-five patients with idiopathic paroxysmal ventricular tachycardia (VT) (13 males, 12 females ; age range 15-59 years) were evaluated with 12-lead electrocardiograms, exercise tests, echocardiographic examinations, 24-hour Holter monitor recordings, invasive electrophysiologic studies, and complete right and left sided cardiac catheterizations withcoronary angiography. No patients had obvious organic heart disease, including mitral valve prolapse. The patients were classified in two groups, group A (n=11) had sustained VT and group B (n=14) had non-sustained VT.

All patients did not experience syncope or shock during their palpitation attacks. Left ventricular ejec-tion fraction ranged from 58% to 78% (mean= 70.6%) in group A and from 64% to 86% (mean= 74.0%) in group B. Twelve-lead electrocardiograms during sinus rhythm were within normal limits in all pati-ents. During VT, left bundle branch morphology was found in 9 patients in group A and 10 patients in group B. VT rate ranged from 133 to 214 beats/min in group A and from 140 to 200 beats/min in group B.

Twenty-one of the 25 patients underwent invasive electrophysiological evaluation. All electrophysio-logical parameters were within normal limits, pacing and programmed stimulation induced VT only in 3 patients in group A and none in group B. During a mean follow-up of 42 months for group A and 29 months for group B, no patients had died suddenly or had cardiac arrest.