体表面心臓電位図に関する研究 第2編 右室負荷疾患の臨床的検討

慢性的右室負荷により右室肥大をきたす疾患は多様である.その原因を血行動態的にみると,右室収縮期圧負荷および右室拡張期容量負荷の2つの負荷様式に大別されるが,両者の合併した負荷様式も臨床的にしばしば見られる.右室肥大の電気生理学的診断法については,Sokolow and Lyon1)の診断基準をはじめとして様々な診断基準2,3)が提唱され未だにそれらの有用性に関する議論が続いている.また,右室肥大の背景としての血行動態差異に基づく心電図波形の差異についても,その有無に関する議論をも含めて多くの報告がみられる.従来の電気生理学的検査法(標準12誘導心電図,ベクトル心電図)による諸家の臨床的検討では,右室肥大の血行動態的負荷様式を識別し得る根拠としてあげられた所見は主に定性的なものである.著者は,第1編に於いて,実験的右室圧負荷犬の電気生理学的所見と病理解剖学的所見を対比検討した結果右室肥大の診断上,右前胸部及び背部にも多くの誘導点をもつ体表面電位図が標準12誘導心電図にない診断情報を含んでいることを示した. Blumenscheinら4)は,小児の心房中隔欠損症,Fallow 4徴症及び肺動脈弁狭窄症について体表面心臓電位図を検討した結果,体表面心臓電位図は圧負荷に基づく右室肥大と容量負荷に基づく右室肥大を鑑別し得る診断情報を含んでいると示唆した.そこで,この体表面電位図を用い,右室負荷疾患39例(原発性肺高血圧症4例,肺動脈狭窄症7例,二次口心房中隔欠損症17例,肺高血圧症合併二次口心房中隔欠損症11例)について臨床的に右室負荷疾患の血行動態的差異を定量的指標により判別しうるか否かについて検討した.また標準12誘導心電図より得た右室肥大診断基準項目の評価も同時に行った.

In order to diagnose right ventricular hypertrophy (RVH) more precisely and quantitatively, isopotential body surface mappings (MAPs) and standard 12 lead electrocardiograms (ECGs) were studied in 39 patients with three different hemodynamic types of chronic right ventricular overload. Sokolow and Lyon's criteria were useful in detecting right ventricular overload. However, ECG parameters were not useful in differentiating between hemodynamic states. The increase of R max･V from precordial leads was thought to be characteristic of right ventricular pressure overload. The Increase in S max･V from right precordial leads was thought to be characteristic of right ventricular volume overload, while the increase in S max･V from left lateral chest and left back leads reflected right ventricular volume and pressure overload. T max･V showed no significant findings. The prolongation of R max･T in the right precordial area was thought to be characteristic of right ventricular volume overload, while the prolongation of R max･T in the left high back was regarded as indicating hypertrophy in the right ventricular outflow tract due to pressure overload. The prolongation of S max･T in the right precordial area was thought reflect right ventricular pressure overload, while the prolongation of S max･T in the left high back was regarded as indicating right ventricular volume overload. The prolongation of VAT (V1), BT time and QRS interval suggested chronic right ventricular volume overload. R max･V (F4), S max･V (I3) and QRS interval were selected for analysis of variance, and discriminant analysis was made using these variables. Twenty nine out of 39 patients were classified correctly, and the accuracy of discrimination was 74.4%.