What we believed to be a right upper pulmonary vein by transthoracic echocardiography is actually a right lower pulmonary vein.

BACKGROUND Current guidelines recommend that pulmonary vein (PV) velocity should be recorded by using the right upper pulmonary vein (RUPV) during transthoracic echocardiography (TTE) evaluation of left ventricular diastolic function. However, it is uncertain whether the PV displayed during TTE is truly measuring the upper PV. This study aimed to identify the actual site of each PV that is usually detected during TTE. METHODS We retrospectively studied 105 patients who underwent cardiac computed tomography (CT) and TTE, reconstructed images three-dimensionally, and measured the angles between each PV and the left ventricle (LV) that would correspond to the Doppler incident angle of the apical four-chamber view on TTE. We also performed TTE during catheter ablation to confirm the exact site of the PV. RESULTS Apical four-chamber views on TTE revealed that one certain PV was detectable on the right side of the vertebra. CT scans revealed that the median angle of the axes between the LV and right lower pulmonary vein (RLPV) was smaller than that of RUPV {32.1˚ [interquartile range (IQR): 21.7˚-42.1˚] vs. 62.5˚ (IQR: 51.6˚-70.6˚), P < .001}. During catheter ablation for treatment of atrial fibrillation, in the most well-displayed PV on TTE, we detected the ablation catheter placed in the RLPV. CONCLUSIONS The most well-displayed PV in an apical four-chamber view by TTE was not the RUPV but the RLPV which showed the smallest angle of incidence toward the LV apex. The RLPV is suitable for evaluation of PV velocity to assess LV diastolic function.