Tissue doppler signals 'reflected' by the fibrous skeleton of the heart cause doppler flow imaging artifacts. Implications for pulmonary venous flow evaluation

Pulsed Doppler signals with high amplitude and low velocity (HALV) are usually labeled as wall artifacts on surface Doppler flow imaging. We hypothesized that HALV signals are actually tissue Doppler waves originating from the strong ultrasound reflectivity of the fibrous skeleton of the heart, and may interfere with measurements of right upper pulmonary vein flow velocities. Using three commercially available ultrasound systems, we recorded in 40 patients (mean age 56 ± 18 years) M-mode tracings of the mitral annulus to derive the peak velocity curve (dD/dt), comparing it to peak HALV waves on pulsed Doppler tracings obtained (4-chamber view) at both an intracardiac flow site (the right upper pulmonary vein) and extracardiac site without flow (3 cm lateral in the left lung). Peak velocities were timed from the ECG Q wave. At both sites, peak Doppler HALV waves ranged from 7 to 36 cm/s. HALV waves were positive in early systole, and negative in early and late diastole, and all matched corresponding dD/dt waves. In late diastole on the right upper pulmonary vein tracing, reverse Doppler flow waves could not be separated from HALV waves in 34/40 patients, because of similar signal amplitude. Time to peak HALV waves at both right upper pulmonary vein and extracardiac sites correlated with time to peak dD/dt (early systole: r= 0.6, p <0.005; early diastole: r= 0.8, p <0.001; late diastole: r= 0.98, p <0.001). In conclusion, Doppler waves showing low velocity and high amplitude on the pulsed Doppler flow surface tracing are reflected tissue Doppler signals originating from the fibrous skeleton of the heart (probably a side-lobe artifact). HALV waves overlap in end-diastole with the reverse right upper pulmonary vein wave. Measurements made on the latter may be unreliable.