Quantification of Aortic Valve Regurgitation by Pulsed Doppler Examination of the Left Subclavian Artery Velocity Contour: A Validation Study with Cardiovascular Magnetic Resonance Imaging

Abstract

Background: Reflux of the aortic regurgitation (AR) causes an increased diastolic reverse flow in the aorta and its branching vessels. We aimed to evaluate the feasibility and accuracy of Doppler measurements in the left subclavian artery (LSA) for quantification of AR in a cardiovascular magnetic resonance imaging (CMR) validation study.

Methods: Systolic and diastolic flow profiles of the LSA (subclavicular approach) were evaluated prospectively by use of pulsed wave Doppler in 59 patients (55.5 ± 15 years; 44 men), 47 with a wide spectrum of AR and 12 as control group. Using CMR phase-contrast sequences (performed 1 cm above the aortic valve), the AR was divided into three groups: mild, regurgitant fraction (RF) < 20% (n = 17); moderate, RF 20%-40% (n = 10); and severe, RF > 40% (n = 20). The LSA Doppler-derived RF was calculated as the ratio between diastolic and systolic velocity-time integrals (VTI).

Results: Quality LSA Doppler signal could be obtained in all cases. Patients with CMR severe AR had higher values of LSA Doppler-derived RF (51% ± 9% vs 36% ± 11% vs 16% ± 8%; P < .0001). LSA Doppler showed a good correlation with CMR, with a sensitivity of 95%, specificity of 89%, and diagnostic accuracy for severe AR of 91.5%. Finally, Bland-Altman plots showed agreement in the group with moderate to severe AR (mean bias = -2.2% ± 8%, 95% CI, -17.7 to 13.3; P = .145) but differed in mild AR.

Conclusions: Measurements of the RF for quantification of AR using LSA Doppler are comparable to those of CMR, highlighting the potential role of LSA Doppler as an adjunctive technique to assess the severity of AR.

Keywords: Aortic valve; CMR; Diastolic flow reversal; Doppler quantification; Left subclavian artery; Regurgitation.