宇宿 弘輝^{1, 2}, 山本 英一郎², 尾池 史², 高潮 征爾², 辻田 賢一²

Hiroki USUKU^{1, 2}, Eiichiro YAMAMOTO², Fumi OIKE², Seiji TAKASHIO², Kenichi TSUJITA²

¹熊本大学病院中央検査部, ²熊本大学大学院生命科学研究部循環器内科学

¹Department of Laboratory Medicine, Kumamoto University Hospital, ²Department of Cardiovascular Medicine, Graduate School of Medical Sciences, Kumamoto University

キーワード : echocardiography, amyloid cardiomyopathy, left ventricular apical sparing

心エコー図検査は心アミロイドーシスのスクリーニングとして重要である．左室granular sparklingは心アミロイドーシスに典型的と言われていたが，心アミロイドーシス以外でも同様の所見のように見えてしまうことがあるため診断意義は薄れている．心エコー図検査における壁肥厚と心電図上の低電位も心アミロイドーシスの特徴的な所見と言われているが，定義上の低電位を認める割合は高くないため，心エコー図検査における心肥大と心電図上の電位の乖離を認めた場合に心アミロイドーシスを疑うべきである．左室Apical sparing現象（左室長軸方向のストレイン値［longitudinal strain: LS］が心基部から低下し，相対的に心尖部のLSが保たれる現象）も心アミロイドーシス診断に有用な所見として注目されているがすべての症例でApical sparing現象を認める訳ではない．また肥大型心筋症，ファブリー病，ミトコンドリア心筋症は，心アミロイドーシスと鑑別を必要とする心筋症として重要であり，これらの疾患における心エコー図所見の特徴を認識しておく必要もある．心エコー図検査は心アミロイドーシスの診断・鑑別に重要であるが限界もあるため，心アミロイドーシスの特徴を理解し，既往歴や家族歴などを「問診」しながら心エコー図検査を行うことが重要である．そして心エコー図検査所見に心電図検査所見や血液検査所見を加えて包括的に検討することで，心アミロイドーシスをスクリーニングすることが可能になる．

Echocardiography is important for raising the pretest probability of amyloid cardiomyopathy before endomyocardial biopsy and ^99mTc-labeled pyrophosphate scintigraphy. Left ventricular (LV) granular sparkling has been reported to be a typical finding in amyloid cardiomyopathy. However, newer echocardiographic image processing techniques may reduce the granular appearance. Thus, the usefulness of granular sparkling as a discriminating factor remains limited. The combination of increased LV thickness and low-voltage electrocardiographic pattern was known to be typical for amyloid cardiomyopathy. However, the rate of low voltage is relatively low in amyloid cardiomyopathy. Thus, a decreased voltage/mass ratio may be useful to diagnose amyloid cardiomyopathy. LV apical sparing pattern, which is a pattern of regional differences in deformation in which the longitudinal strain (LS) in the basal and middle segments of the LV is more severely impaired than that in the apical segment, is also a useful echocardiographic finding for diagnosing amyloid cardiomyopathy. However, we revealed that half of patients with amyloid cardiomyopathy did not have LV apical sparing. Thus, we should recognize the limitations of echocardiographic findings in the diagnosis of amyloid cardiomyopathy. When amyloid cardiomyopathy is suspected, hypertrophic cardiomyopathy, Fabry disease, and mitochondrial cardiomyopathy should be included in the differential diagnosis. Thus, the typical echocardiographic findings of these diseases should be recognized. Although echocardiography is useful for diagnosing and differentiating amyloid cardiomyopathy, there are several limitations. Thus, it is important to perform echocardiography with medical consultation about medical and familial history. Comprehensive assessment with not only echocardiography but also medical consultation, electrocardiography, and laboratory findings enables us to diagnose amyloid cardiomyopathy accurately.