土至田 勉, 上田 宏昭, 茅野 博行, 川又 朋章, 平野 雄一, 江 修博, 斎木 裕香, 浅野 拓, 小林 洋一, 片桐 敬

Tsutomu TOSHIDA, Hiroaki UEDA, Hiroyuki KAYANO, Tomoaki KAWAMATA, Yuichi HIRANO, Shuhaku KOH, Yuka SAIKI, Taku ASANO, Youichi KOBAYASHI, Takashi KATAGIRI

昭和大学医学部第三内科

The Third Department of Internal Medicine, Showa University School of Medicine

キーワード : CARTO system, echocardiography, electro-anatomical mapping system, premature ventricular contraction, tissue tracking method

背景：心臓電気生理検査のelectro-anatomical mapping system (CARTO system^®) の開発により心室性期外収縮の起源に 対する同定が容易となった. 心臓超音波検査では, 組織ドプラ法を応用したtissue tracking 法が開発され, 収縮の伝播過程を画像定量化することが可能となった. 目的：Electro-anatomical mapping system のactivation map から同定された心室性期外収縮の起源との比較からtissue tracking 法の臨床的有用性を検討すること. 方法：対象は, 薬剤抵抗性を呈する心室性期外収縮を高頻度に認め, 低心機能を呈してカテーテル心筋焼灼術を施行する目的で入院した2 症例. Tissue tracking 法を用いて心室性期外収縮の起源を同定後, electro-anatomical mapping system のactivation map を施行. Tissue tracking 法で同定した心室性期外収縮の起源部位と比較検討した. 結果：症例1,2 ともtissue tracking 法で左室流出路に心室性期外収縮の起源を認めた. Electro-anatomical mapping system では, 症例1 は右室流出路附近に, 症例2 では左室流出路附近に起源を認め, カテーテル心筋焼灼術を施行. 心室性期外収縮の消失を認めなかったが, 大動脈弁左冠尖に対するカテーテル心筋焼灼術により心室性期外収縮の消失を認めたため起源と判断, tissue tracking 法で同定した部位と一致すると考えられた. 結語：Tissue tracking 法は心室性期外収縮の起源同定に対し, 簡便かつ非侵襲的で有用な評価方法であることが示唆された.

Background: Identifying a focus of premature ventricular contraction (PVC) in cardiac electrophysiology has been facilitated by the development of the electro-anatomical mapping system (CARTO system^®). The echocardiographic tissue tracking method utilizing the tissue Doppler method can quantify the process of propagation of myocardial contraction. Purpose: To compare the clinical usefulness of the tissue tracking method by comparing its results with results obtained for a focus of PVC identified from an activation map produced using the electro-anatomical mapping system. Methods: The subjects examined were two patients with drug-resistant PVC who had been admitted for catheter ablation for low cardiac function. After identifying the focus of PVC with the tissue tracking method, we acquired an activation map produced using the electro-anatomical mapping system, and compared it with the focus of PVC identified by the tissue tracking method. Results: The tissue tracking method showed a focus of PVC near the left ventricular outflow tract in both cases. The electro-anatomical mapping system showed the focus of PVC near the right ventricular outflow tract in case 1 and near the left ventricular outflow tract in case 2. Although catheter ablation did not resolve PVC, PVC disappeared on catheter ablation of the left coronary cusp of the aortic valve. We thus judged the left coronary cusp to be the likely focus. This focus was deemed to be consistent with the region identified by the tissue tracking method. Conclusion: The results recommend the tissue tracking method as simple, noninvasive, and useful in evaluating and identifying the focus of PVC.