Natural Shear Wave Elastography

BACKGROUND: Noninvasive assessment of myocardial properties and hemodynamics in Fontan patients remains challenging. Natural shear wave (SW) elastography is a promising new echocardiographic modality that allows noninvasive assessment of myocardial stiffness using the velocity of naturally occurring SWs detected with high frame rate (HFR) imaging. OBJECTIVES: The objectives of the study were to document SW speed after atrioventricular valve closure (AVVC) and outflow valve closure in Fontan patients; to compare it with age-matched healthy volunteers; and to investigate the relation between SW speed, clinical features, and systemic venous pressures (SVPs). METHODS: The authors enrolled 47 Fontan patients (mean age: 19 ± 11 years, range 3-46y range: 3-46 years). For all, we acquired clinical data, conventional echocardiographic parameters, HFR parasternal long-axis views, and SVP when available (n = 30). HFR images were processed offline by extracting tissue Doppler acceleration color-coded maps of M-modes drawn in the middle of the wall related to both the inflow and the outflow valve. RESULTS: Average SW speeds were higher in Fontan patients than in healthy volunteers (5.3 ± 1.6 m/s vs 3.0 ± 0.5 m/s after AVVC, P < 0.001; 5.1 ± 2.0 m/s vs 3.4 ± 0.6 m/s after outflow valve closure , P < 0.001). Patients with Fontan circulatory failure had increased SW speed compared to well-functioning Fontan patients (6.3 ± 1.4 m/s vs 4.9 ± 1.5 m/s; P = 0.008). SW velocities after AVVC correlated moderately to SVP (r = 0.55, P = 0.002), whereas no other conventional diastolic parameter did. CONCLUSIONS: Our findings suggest that Fontan hearts may be stiffer than normal and that SW velocities are higher in patients with a Fontan circulatory failure. Moreover, SW speed was related to SVP.