1 聖路加国際病院臨床検査科生理機能検査室Clinical Laboratory, St. Luke’s International Hospital
2 聖路加国際病院循環器内科Department of Cardiology, St. Luke’s International Hospital
3 聖路加国際病院心臓血管外科Department of Cardiovascular Surgery, St. Luke’s International Hospital
目的：大動脈弁閉鎖不全症（Aortic Regurgitation: AR）の重症度評価で用いる下行大動脈Reverse flowが適応外となる動脈硬化の程度を明らかにすること．
対象と方法：心臓超音波検査と胸部CT（Computed Tomography）を同時期に受けた軽度以下のARで65歳以上の167人（平均年齢74±9歳）を解析対象とした．左室拡張能指標，上行大動脈のStiffness indexなどを計測し，下行大動脈のReverse flow陽性，陰性の2群で比較した．Reverse flowは胸骨上窩アプローチで拡張末期に18 cm/s以上の逆流を認めたものを陽性とした．
結果と考察：軽度以下のARの高齢者63人（38%）に平均20±2 cm/sのReverse flowを認めた．多変量解析ではStiffness index＞11.8 (odds比＝2.1, 95%CI＝1.0–4.4, p＝0.049)，CTの大動脈石灰化所見（odds比＝8.7, 95%CI＝2.5–31, p＜0.001）で偽陽性Reverse flow出現の予測能が高かった．CT未施行例ではStiffness indexが参考になると考える．
結論：胸部CTで大動脈石灰化所見，上行大動脈のStiffness index上昇がある症例は下行大動脈のReverse flowが偽陽性となる可能性が高いためAR重症度評価の際に注意が必要である．
Purpose: To clarify the extent of arteriosclerosis that invalidates descending aortic reverse flow (DARF) use in assessing aortic regurgitation (AR) severity.
Subjects and Methods: A total of 167 patients aged ≥65 years (mean age: 74±9 years) with no more than mild AR who underwent both echocardiography and chest computed tomography (CT) during the same period were analyzed. Parameters such as left ventricular diastolic function indices and the ascending aortic stiffness index (AASI) were measured. The participants were classified into two groups based on the presence or absence of DARF, which was defined as a retrograde flow velocity of ≥18 cm/s in late diastole detected using a suprasternal approach.
Results and Discussion: DARF with an average velocity of 20±2 cm/s was observed in 63 elderly patients (38%) with no more than mild AR. Our multivariate analysis revealed that a stiffness index ＞11.8 (odds ratio＝2.1, 95% CI＝1.0–4.4, p＝0.049) and aortic calcification findings on CT (odds ratio＝8.7, 95% CI＝2.5–31, p＜0.001) were strong predictors of false-positive reverse flow. In cases where CT was not performed, the stiffness index was considered a useful reference.
Conclusion: Patients with aortic calcification on chest CT or an elevated AASI are highly predisposed to false-positive reverse flow in the descending aorta, warranting caution when evaluating AR severity.
Key words: Aortic Regurgitation; Reverse flow; arteriosclerosis
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