体表面心臓電位図に関する研究 第1編 右室肥大(収縮期負荷)の実験的検討

右室圧負荷の原因疾患として,肺動脈弁狭窄症,原発性肺高血圧症,及び肺高血圧を伴った心室中隔欠損症,動脈管開存症などがあげられる.これらの病理解剖学的特徴は求心性の右室肥大で,その電気生理学的反映として,心電図,ベクトル心電図に,収縮期負荷として特有の右室肥大所見を認める.しかし,心電図,ベクトル心電図の右室肥大所見は,その原因疾患および病態,経過により著しい差を示し,多くの判定基準1～3)が提唱されている.しかもこれらの基準はいずれも,主として右室肥大の存在を定性的に示し,定量的な判定には十分でない.そこで右前胸部及び背部にも多くの誘導点を有し,体表面電位と時間的変化を同時に表現し得る体表面電位図(電位図)を用い,右室圧負荷に伴う右室の求心性肥大をより詳細に分析し,かつ,その定量的評価の可能性を実験的に検討する目的で犬に肺動脈絞扼術を施行し慢性右室圧負荷を作成した.そして右室肥大の経時的進展に伴う電位図変化を観察し,病理解剖学的所見と対比検討した.更に,標準12誘導心電図の経時的変化についても検討を行った.

In order to diagnose right ventricular hypertrophy (RVH) more precisely and quantitatively, body surface isopotential mappings (MAPs) and standard 12 lead ECGs (ECGs) were recorded in pulmonary artery banded dogs and sham operated dogs before and after surgery. MAP and pathoanatomical findings (RV/LV weight ratio) were compared, and the relationships among the MAP and ECG parameters were examined. Pathoanatomical RVH (RV/LV weight ratio>0.65) developed 12 months after PA banding. The indices derived from MAPs were analyzed statistically by one way analysis of variance. After PA banding, R max･V gradually increased on the anterior-inferior chest surface, S max･V increased on the left high back, T max･V increased on the lower chest surface and the R max ratio and RV/LV weight ratio were correlated (r=0.55, p<0.1), so R max ratio may reflect anatomical RVH quantitatively. These changes were statistically significant (p<0.05), while the usual parameters for diagnosing RVH such as QRS axis, R/S (V1), RV1, SV5, SV6, RV1+SV5 and VAT (V1) showed no significant changes after the operation. The foregoing findings suggest that MAP is superior to conventional ECG for diagnosis of RVH.