小形 幸代

Yukiyo OGATA

自治医科大学内科学講座循環器内科学部門

Department of Cardiovascular Medicine, Jichi Medical University School of Medicine

キーワード : left ventricular hypertrophy, left ventricular mass index, concentric hypertrophy, eccentric hypertrophy

左室肥大は健診などの心電図で偶発的に指摘されることが稀ではなく，心エコー図はその診断や原因検索をするうえで，最も安全かつ有効な検査法である．左室肥大の原因は圧負荷や容量負荷などの外因性，遺伝的な要因，異常物質の沈着など様々である．左室肥大は心血管イベントの発症，予後の予測因子となるため，左室肥大の程度を評価することは臨床的にとても重要である．左室肥大は左室壁の肥厚のみを意味するのではなく，個々の心筋細胞の増大によって心筋全体の重量が増加している状態のことである．この左室肥大の様式は相対的左室肥厚および左室心筋重量係数により求心性肥大と遠心性肥大に分類される．心筋重量係数の測定にはリニア法と断層法があり，左室の形態異常がある場合は断層法が推奨されている．いずれの方法においても，左室壁や左室内腔の計測を正確に行う必要があり，正しい位置で計測することや心室内の他の構造物を誤って計測しないことが基本となる．左室壁の肥厚の程度やその分布から左室肥大の原因を鑑別していくが，心エコー図のみで原因を特定することは困難である．家族歴，身体所見，種々の検査結果と合わせて総合的に判断することが重要である．

Left ventricular (LV) hypertrophy is not uncommonly discovered incidentally on electrocardiograms taken as part of medical checkups. Echocardiography is the safest and most effective examination method for diagnosing it and searching for the cause. The causes of LV hypertrophy are various, including extrinsic factors such as pressure overload and volume overload, genetic factors, and deposition of abnormal substances. Because LV hypertrophy is a predictor of cardiovascular events and prognosis, it is of great clinical importance to assess the degree of LV hypertrophy. LV hypertrophy does not mean only thickening of the LV wall but also an increase in the mass of the entire myocardium due to enlargement of individual myocardial cells. LV hypertrophy is classified into concentric hypertrophy and eccentric hypertrophy according to relative wall thickness and left ventricular mass index (LVMI). LVMI is measured using either the linear method or the tomographic method. The tomographic method is recommended when the LV is morphologically abnormal. Whichever method is used, accurate measurement of the LV wall thickness and lumen is important. It is fundamental to measure them at the correct position and not to mistakenly measure other structures inside the ventricles. The cause of LV hypertrophy is determined based on the degree of the LV wall thickness and its distribution. However, it is difficult to specify the cause of LV hypertrophy based solely on echocardiography, and it is important to make a comprehensive judgment together with family history, physical findings, and various examinations.