Pan-Diastolic Flow Reversal in the Subclavian Artery: An Indicator of Aortic Insufficiency

Introduction. —For many labs, Doppler evaluation of the subclavian artery (SCA) is routinely included in the carotid protocol. At our center, we have noted that many patients have a unique SCA waveform present bilaterally, characterized by flow reversal throughout the entire diastolic interval. The purpose of this study was to define the cause and significance of these atypical SCA waveforms.

Methods. —During a 6-month period, 21 patients with normal bilateral SCA waveforms, who also had Doppler echocardiography (DEC), were evaluated for the presence of aortic insufficiency (AI). Similarly, 25 patients who had pan-diastolic flow reversal (PDFR) in their SCAs bilaterally were also evaluated for the presence of AI on DEC. Patients with upper extremity deep vein thrombosis (DVT), bypass grafts, compartment syndrome, or dialysis access were excluded from this investigation.

Results. —Of the 25 patients with bilateral SCA PDFR, 20 patients had aortic regurgitation present on DEC. Normal triphasic waveforms were present bilaterally in 21 patients. Of these, 20 patients had no evidence of AI by DEC. Statistical analysis resulted in a sensitivity of 80%, specificity of 95%, positive predictive value of 95%, and an overall accuracy of 87% for the detection of AI by SCA Doppler evaluation.

Conclusion. —PDFR in the SCA bilaterally is a waveform associated with AI. Although DEC is the preferred technique for the evaluation of suspected aortic valve dysfunction, many patients with this condition have no detectable murmur or other indication of this condition. Consequently, the identification of this unique waveform in both SCAs during carotid duplex may provide useful clinical information and lead to additional cardiac workup.