Natural Shear Wave Elastography: A Promising Tool to Assess Myocardial Stiffness in Fontan Patients

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.

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).

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.

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.

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.