Pu M, Vandervoort P M, Griffin B P, Leung D Y, Stewart W J, Cosgrove D M, Thomas J D
Cardiovascular Imaging Center, Cleveland Clinic Foundation, OH 44195-5064, USA.
Circulation. 1995 Oct 15;92(8):2169-77. doi: 10.1161/01.cir.92.8.2169.
Proximal flow convergence is a promising method to quantify mitral regurgitation but may overestimate flow when the flow field is constrained. This has not been investigated clinically, nor has a correction factor been validated.
Eighty-five patients were studied intraoperatively with transesophageal echocardiography and divided into two groups: central convergence (no constraining wall) and eccentric convergence (at least one constraining wall). Regurgitant stroke volume (RSV) and orifice area (ROA) were calculated by ROA = 2 pi r2 Va/Vp and RSV = ROA x VTIcw, where r and va are the radius and velocity of the aliasing contour and vp and VTIcw are the peak and integral of regurgitant velocity. In eccentric convergence patients, convergence angle (alpha) was measured from two-dimensional Doppler color flow maps, and ROA and RSV were corrected by multiplying by alpha/180. For reference, RSV was the difference between thermodilution and pulsed Doppler stroke volumes. In central convergence patients (n = 45), RSV (r = .95, delta = 2.5 +/- 10.8 mL) and ROA (r = .96, delta = 0.02 +/- 0.08 cm2) were accurately calculated, but significant overestimation was noted in the eccentric convergence patients (n = 40, delta RSV = 63.9 +/- 38.0 mL, delta ROA = 0.54 +/- 0.31 cm2), 68% of whom had leaflet prolapse or flail. delta RSV was correlated with alpha (r = -.69, P < .001). After correction by alpha/180, overestimation was largely eliminated (delta RSV = 15.5 +/- 19.3 mL and delta ROA = 0.14 +/- 0.14 cm2) with excellent correlation for the whole group (RSV, r = .91; ROA, r = .95).
A simple geometric correction factor largely eliminates overestimation caused by flow constraint with the proximal convergence method and should extend the clinical utility of this technique.
近端血流会聚是一种很有前景的量化二尖瓣反流的方法，但当流场受限时可能会高估血流量。这一点尚未在临床上进行研究，校正因子也未得到验证。
对85例患者进行术中经食管超声心动图检查，并分为两组：中心会聚（无限制壁）和偏心会聚（至少有一个限制壁）。反流搏出量（RSV）和瓣口面积（ROA）通过ROA = 2πr²Va/Vp和RSV = ROA×VTIcw计算得出，其中r和Va是混叠轮廓的半径和速度，Vp和VTIcw是反流速度的峰值和积分。在偏心会聚患者中，从二维多普勒彩色血流图测量会聚角（α），并通过乘以α/180来校正ROA和RSV。作为参考，RSV是热稀释法和脉冲多普勒搏出量之间的差值。在中心会聚患者（n = 45）中，RSV（r = 0.95，差值 = 2.5±10.8 mL）和ROA（r = 0.96，差值 = 0.02±0.08 cm²）计算准确，但在偏心会聚患者（n = 40，差值RSV = 63.9±38.0 mL，差值ROA = 0.54±0.31 cm²）中发现有显著高估，其中68%的患者有瓣叶脱垂或连枷样改变。差值RSV与α相关（r = -0.69，P < 0.001）。经α/180校正后，高估在很大程度上被消除（差值RSV = 15.5±19.3 mL，差值ROA = 0.14±0.14 cm²），全组相关性良好（RSV，r = 0.91；ROA，r = 0.95）。
一个简单的几何校正因子在很大程度上消除了近端会聚法因血流受限导致的高估，应能扩展该技术的临床应用。
