1 群馬県立心臓血管センター技術部Department of Medical Technology, Gunma Prefectural Cardiovascular Center
2 群馬県立心臓血管センター循環器内科Department of Cardiology, Gunma Prefectural Cardiovascular Center
目的：僧帽弁輪部断面積（CSAMV）の計測には，心尖部四腔，二腔像の弁輪径を用いる4CV/2CV法よりも，長軸像の弁輪径（DLAX），交連部–交連部の径（DCC）を用いるLAX/CC法の方が正確であるとの報告がある．本研究の目的は，4CV/2CV法とLAX/CC法で計測したCSAMVから左室流入血流量（QLVIT）を算出し，その計測精度を比較すること，DCCおよびDLAX計測の最適断面を検討することである．
対象と方法：対象は，明らかな弁膜症がなく心機能良好とした30例（M/F: 22/8, 48.7±18.6歳）．4CV/2CV法に加え，LAX/CC法は心尖部アプローチおよび傍胸骨アプローチでDCC, DLAXを計測し，その組み合わせから4種類の方法で各CSAMVを求めた．4CV/2CV法とLAX/CC法によるQLVITを算出し，左室駆出血流量（QLVOT）を対照に計測精度を比較した．
結果と考察：4CV/2CV法で認めた計測誤差は，LAX/CC法で改善した．特にDCC, DLAXともに傍胸骨アプローチで計測した方法が，QLVOTと最も良く相関し（r＝0.925, p＜0.01），計測誤差が小さくなった．傍胸骨アプローチでは，DLAXを超音波ビームに対し垂直に描出できること，DCCの計測に短軸断面を用いることで交連の位置を正確に把握できたことが測定精度の改善につながったと考えられた．
結論：LAX/CC法によるCSAMVの計測は，QLVITの測定精度を改善させる．その際，DLAX, DCCともに計測断面の描出は傍胸骨アプローチが有用である．
Purpose: Calculation of mitral annular cross-sectional area (CSAMV) using the diameters from the apical long-axis and commissural plane (LAX/CC) method could be more accurate than the calculated area obtained by the annular diameters in the conventional apical four- and two-chamber view (4CV/2CV) method. The purpose of the study is to clarify which approach gives better accuracy: to use the 4CV/2CV method from the apical view or to use the LAX/CC method from the apical view or the parasternal view.
Subjects and Methods: Thirty patients without valvular heart diseases were enrolled in this study (22 males, 8 females, 48.7±18.6 years old). CSAMV was measured by three methods as follows: using the conventional 4CV/2CV method from the apical view, and using the LAX/CC method from the apical view and the parasternal view. Left ventricular inflow volume (QLVIT) was calculated using CSAMV obtained by each method. LV outflow volume (QLVOT) was measured by the Doppler method. Correlations and differences between QLVOT and QLVIT were compared among the three methods.
Results and Discussion: Compared with the 4CV/2CV method, QLVIT values by the LAX/CC method from the two views were well correlated with QLVOT (4CV/2CV method: r＝0.745, p＜0.01 LAX/CC method from apical view: r＝0.799, p＜0.01 LAX/CC method from parasternal view: r＝0.925, p＜0.01). Further analysis with Bland–Altman plots revealed that the QLVIT obtained by the LAX/CC method from the parasternal view exhibited the closest agreement with QLVOT.
Conclusions: CSAMV obtained by the LAX/CC method for both apical and parasternal views is more accurate than that obtained by the conventional 4CV/2CV method. Moreover, the LAX/CC measurement from the parasternal view is better than from the apical view.
Key words: Left ventricular inflow volume (QLVIT); mitral annular cross-sectional area (CSAMV); long-axis mitral annulus diameter; commissural mitral annulus diameter; volumetric method
© 2016 一般社団法人日本超音波検査学会© 2016 Japanese Society of Sonographers
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