心筋脂肪酸代謝シンチグラフィ(123I-BMIPP)を用いて右心負荷所見を評価し得た1例

Right Ventricular Pressure Overload was Evaluated using 123I-β-methyl Idiophenyl Pentadecanoic Acid(BMIPP)Myocardial Scintigraphy:A Case Report

要旨　心臓核医学検査による右心負荷評価法には²⁰¹Tlを用いたCohen基準が用いられている．一方，心筋脂肪酸代謝シンチグラフィ(¹²³I-BMIPP)は虚血性心疾患の虚血領域や心筋生存性および治療効果判定に汎用されているが，右心系の評価法には使用されていない．現在までに右室圧の上昇の程度に比例して¹²³I-BMIPPの右室への集積が亢進するとの報告がある．しかし，推定右室圧80mmHg以上の重度の右心負荷所見を呈した場合には，逆に¹²³I-BMIPPの右室への集積は低下するとの報告もあり，現時点では¹²³I-BMIPPを用いた右心系の評価法には一定の見解は示されていない．今回，われわれは急性左心不全例に対して¹²³I-BMIPPを施行したところ，右心負荷所見と評価し得る¹²³I-BMIPPの右室集積亢進所見を呈した1例を経験したので報告する．

　Cohen's classification using thallium-201 myocardial scintigraphy has been adopted as a standard method for the assessment of right ventricular pressure overload in the field of cardiac nuclear medicine. On the other hand, ¹²³I-β-methyl iodophenyl pentadecanoic acid(¹²³I-BMIPP)is widely used to identify the ischemic area, assess myocardial viability, and evaluate the response to treatment in patients with ischemic heart disease. However, it has not been used to evaluate the right heart system. Previous reports indicated that an increased ¹²³I-BMIPP uptake in the right ventricle is proportional to an increase in the right ventricular pressure. However, other reports have demonstrated that ¹²³I-BMIPP uptake decreases in patients with severe right ventricular overload at an estimated right ventricular pressure of 80mmHg or higher. Therefore, no consensus has been reached on the feasibility of evaluating right heart failure by using ¹²³I-BMIPP.

Here we report a case of right ventricular pressure overload identified using ¹²³I-BMIPP infusion in a patient with acute congestive heart failure. Right ventricular pressure overload should be suspected in patients exhibiting an increased ¹²³I-BMIPP uptake in the right ventricle.