運動負荷時の循環動態指標を連続モニターしえた家族性アミロイドポリニューロパチー(FAP type I)の孤発例

Dynamic Monitoring during Exercise in Familial Amyloid Polyneuropathy(FAP)Type I

要旨

　患者は64歳，男性．失神，下痢の精査で入院し，身体所見で起立性低血圧に加え下肢遠位部優位の感覚障害を認めた．心臓超音波で左室に著明な拡張障害，両心室の肥大，granular sparklingを認めた．^99mTc-PYP心筋シンチでは両心室に高度の集積を認め，¹²³I-MIBG心筋シンチでは心臓への集積は全く認めなかった．心筋生検でアミロイド沈着を認め，トランスサイレチン(以下TTR)の遺伝子解析を行いFAP type Iと診断された．本症例において，Physio Flow^TM Lab-1を用いた非侵襲的手法により運動負荷中の血行動態を連続モニターしたところ，運動に伴い著明な血圧の低下を認めた．この機序として，心係数の変動は認めないことから，運動に伴う末梢血管抵抗の著しい低下が大きく関与していることが示唆された．患者は代々滋賀県在住であり，FAP type Iの孤発例と考えられる．

Summary

A 64-years-old man was admitted to our hospital with complaints of orthostatic faintness and occasional diarrhea. An echocardiogram of the left ventricule demonstrated a severe restrictive disorder and granular sparkling appearance in the thickened walls. Microscopic findings of the myocardial biopsy revealed massive intramuscular accumulation of eosinophilic exudates and severe atrophy of myocytes. Cardiac ^99mTc-pyrophosphate(PYP) findings showed diffuse marked uptake in both left and right ventricules. Cardiac ¹²³I-meta-iodobenzyl-guanidine(MIBG) findings showed complete defect on both early and delayed images. Genetic analysis revealed a single amino acid substitution at codon 30 of transthyretine(TTR), named FAP type I. Dynamic monitoring of the cardiac index and peripheral vascular resistance in postural positions and exercise was measured by non invasive methods(Physio Flow^TM Lab-1). The results of analysis indicated that the fall in blood pressure during exercise in our case was markedly affected by the lowering of peripheral vascular resistance. The cardiac index showed almost the same value during monitoring.

　These findings suggest that orthostatic hypotension without increase in heart rate and output in a denervated myocardium is markedly accelerated by peripheral vascular sympathetic denervation in FAP type I. The present case is considered to be the first one encountered in Shiga.