長期QT症候群における心筋収縮のトランスムラ差異:イオンチャネル機能障害の機械的影響
Kristina Hermann Haugaa1, Jan P Amlie, Knut Erik Berge
1Department of Cardiology, Oslo University Hospital, Oslo, Norway.
Circulation
|September 22, 2010
まとめ
ロングQT症候群 (LQTS) の患者は,特に心下腸内臓では,心臓筋の収縮が長時間続くことを示す. このトランムラル機械的分散は,症状のあるLQTS個体における心律乱症のリスクと関連しています.
科学分野:
- 心臓病学 心臓病学
- 心臓電気生理学 心臓電気生理学
- エコーカルディオグラフィー エコーカルディオグラフィー
背景:
- ロングQTシンドローム (LQTS) は,心筋動脈のアクションポテンシャル期間が長くなることが特徴である状態です.
- この延長が最も顕著なのは,心内膜と心中膜にある.
- 延長されたアクションポテンシャルの持続期間は,ストレートエコーカルディオグラフィーで検出可能な延長された心臓収縮につながる可能性があります.
研究 の 目的:
- LQTS患者における心筋収縮が最長期間続くのは心下筋線維にあるかどうかを調べる.
- 不均質なトランスムラル収縮が,LQTSにおける自発性不律症のリスクと相関するかどうかを判断する.
主な方法:
- ストレインエコーカルディオグラフィは,左心室 (LV) の16段で心筋収縮期間を評価するために使用されました.
- 収縮期間は,EKG Q波からピークストレスのまでの時間として測定されました.
- ストレインは,縦軸 (下心内繊維) と周囲軸 (心筋内繊維) に沿って分析された.
主要な成果:
- 平均収縮期間は,LQTS変異のキャリアで (445 ± 45 ms) 健康な個体 (390 ± 40 ms) よりも著しく長かった.
- 症状のあるLQTSキャリアは,無症状のキャリア (425 ± 45 ms) に比べて,より長い収縮期間 (460 ± 40 ms) を示した.
- 症状のあるLQTS患者では,縦方向のストレスの持続時間は,周囲のストレスの持続時間 (460 ± 45 ms vs. 445 ± 45 ms) を上回り,トランムラルメカニカル分散を示しています.
結論:
- 症状のあるLQTS変異のキャリアは,中心筋と下心筋の収縮期間が長引くことを示しています.
- このトランムラルメカニカル分散は,症状のあるLQTSにおいて,心臓のメカニズムが変化していることを示している.
- 症状のないLQTS患者または健康な個体では,トランスムラルの機械的な分散は観察されなかった.
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