Volcano Therapeutics Virtual HistologyTM IVUSがslow flow現象の病態評価に有用であった狭心症の1例

Assessment of Slow Flow Phenomenon in a Patient with Angina Pectoris using Volcano Therapeutics Virtual HistologyTM IVUS：A case report

　冠動脈プラークの組織性状を評価する方法としてgray scale IVUSが用いられてきたが，近年，より詳細に組織性状を評価できるVolcano Therapeutics Virtual Histology^TM IVUS(VH IVUS)が臨床応用された．VH IVUSでは後方散乱信号を使用することによりプラークを線維組織，線維性脂質組織，石灰化や脂質壊死組織に診断できる．今回，VH IVUSが病態評価に有用であった狭心症例を経験したので報告する．患者は59歳の男性で，左前下行枝に高度な狭窄病変が認められたために経皮的冠動脈形成術が施行されたが，ステント留置直後に高度な造影遅延が生じた．ステント留置前に施行したgray scale IVUSでは石灰化を伴う線維性組織で安定プラークと判断されたが，VH IVUSでは脂質壊死組織が認められ不安定組織であった可能性が示唆された．今後，VH IVUSの使用により詳細なプラークの組織診断が可能になり，slow flowなどの合併症が予測可能になることが示唆された．

Intravascular ultrasound(IVUS) has been used as the modality for evaluating plaque composition. In recent years, Volcano Therapeutics’ Virtual Histology^TM IVUS(VH IVUS) has proven to be clinically feasible, combining integrated backscatter signals with spectral parameters, which are reported to be able to identify fibrotic, fibro-fatty, dense calcium and necrotic core within atherosclerotic plaque. We report a case in which VH IVUS was useful to evaluate the histological characteristics of atherosclerotic plaque. A 59-year old man, who had severe stenosis at the mid-segment of the left anterior descending coronary artery, underwent percutaneous coronary intervention. Immediately after stent implantation, a serious slow flow phenomenon occurred in the left anterior descending coronary artery. In this case, coventional gray-scale IVUS revealed that the culprit lesion consisted mainly of stable fibrotic plaque with superficial calcification, whereas VH IVUS demonstrated unstable plaque with not only calcification but also necrotic core. It is suggested that IVUS, being able to evaluate tissue characteristics, may be able to predict the complication of slow flow phenomenon. VH IVUS might have the ability to evaluate tissue characteristics, predicting the complication of the slow flow phenomenon.