Effect of jet direction on pulmonary venous flow: Importance for estimation of mitral regurgitation by venous flow pattern

Although previous studies showed that pulmonary venous (PV) flow could be used for assessing mitral regurgitant (MR) severity, variable clinical results have been observed. Fluid dynamic simulation showed that jet direction may impact PV flow, but clinical data are lacking. We prospectively studied 32 patients (pts) with MR. The left and right upper PV flows were recorded by transesophageal echocardiography (TEE). Peak systolic PV velocity (SPV), systolic velocity-time integral (S_VTI), diastolic velocity-time integral (D_VTI), systolic to diastolic velocity (S/D) ratio and systolic to diastolic velocity-time integral (S_VTI/D_VTI) ratio were measured. MR jet was mapped by multiplane color Doppler TEE. Effects of jet direction on PV flow were classified into 1) Jet towards PV; 2) Jet not towards PV. Results: SPV(cm/s) S/D SVTI S_VTID_VTI Jet not towards PV 5±43 0.30±1.14 2.23±6.1 0.37±1.03 Jet towards PV -33±56* -0.67±1.47* -3.20±7.9* -0.24±1.31* Systolic PV flow was decreased more significantly in PV with the jet towards them than in the others (table *p<0.001). Estimation of MR by S/D and S_VTI/D_VTI ratios was more severe in pts with jet towards PV than those without. Most of patients with reversal flow pattern had jet either towards or entering PV. Conclusions: Jet direction significantly impacts PV flow. Variable PV flow may result from different jet direction. This local factor should be considered when pulmonary venous flow pattern is used to estimate MR severity.