Discordant Superior Vena Cava and Hepatic Vein Doppler: A Physiologic and Imaging Framework

Spectral Doppler interrogation of the superior vena cava (SVC) and hepatic veins (HVs) provides important insight into right heart filling dynamics. Under normal conditions, venous flow patterns in both conduits are generally similar, reflecting their shared dependence on fluctuations in right atrial pressure. However, SVC and HV waveforms are not identical, as they are modulated by differences in anatomical location, venous compliance, compartment-specific expression of transmitted right atrial pressure, and susceptibility to extracardiac influences. The subtle physiologic distinctions between the 2 conduits become accentuated in some disease states, underscoring that SVC and HV Doppler signals convey complementary rather than redundant hemodynamic information. In many right heart disorders, abnormal venous Doppler patterns remain concordant between the 2 vessels, demonstrating parallel alterations in waveform characteristics. In contrast, selected physiologic, cardiac, and vascular/extracardiac conditions produce SVC-HV discordance, manifested as differences in Doppler velocity, waveform morphology, flow direction, or respiratory modulation. Recognition of such discordance has clinically relevant implications, including refinement of tricuspid regurgitation severity assessment, improved estimation of right-sided filling pressures, and enhanced detection of constrictive physiology. As right heart-focused imaging and transcatheter tricuspid valve interventions continue to expand, accurate interpretation of venous Doppler discordance is increasingly relevant, and failure to recognize these patterns may lead to incomplete or misleading hemodynamic assessment. In this focused review, we outline the physiologic determinants of SVC and HV Doppler waveforms and examine representative conditions associated with discordant venous flow patterns. By integrating Doppler observations with their underlying physiologic mechanisms, we propose a practical framework to guide interpretation of SVC-HV discordance and emphasize the diagnostic value of systematic interrogation of both venous systems.