Pulsed-Wave Doppler Recordings in the Proximal Descending Aorta in Patients with Chronic Aortic Regurgitation: Insights from Cardiovascular Magnetic Resonance

Abstract

The pulsed-wave Doppler recording in the descending aorta (PWDDAO) is one of the parameters used in grading aortic regurgitation (AR) severity. The aim of the present study was to investigate the assessment of chronic AR by PWDDAO with insights from cardiovascular magnetic resonance (CMR). This prospective study comprised 40 patients investigated with echocardiography and CMR within 4hours either prior to valve surgery (n=23) or as part of their follow-up (n=17) due to moderate or severe AR. End-diastolic flow velocity (EDFV) and the diastolic velocity time integral (dVTI) were measured. The appearance of diastolic forward flow (DFF) was noted. Phase-contrast flow rate curves were obtained in the DAO. Twenty-five patients had severe and eight had moderate AR by echocardiography (seven were indeterminate). The EDFV was below the recommended threshold (>20cm/sec) in 13 patients (52%) with severe AR. Lowering the EDFV threshold (>13cm/sec) and with a dVTI threshold >13cm showed negative likelihood ratios of 0.27 and 0.09, respectively. Detection of DFF with PWDDAO identified a nonuniform velocity profile by CMR with positive and negative likelihood ratios of 7.0 and 0.19, respectively. The relation between EDFV and DAO regurgitant volume (DAO-RVolCMR) was strong in patients without (R=0.88) and weak in patients with DFF (R=0.49). The DAO-RVolCMR as a percent of the total RVolCMR decreased with increasing ascending aorta (AAO) size and increased with increasing AR severity. Our findings suggest that PWDDAO provides semiquantitative parameters useful to assess chronic AR severity. The limitations are related to nonuniform velocity contour and variable degree of lower body contribution, which depends on AR severity but also on the AAO size.