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

Area of Science:

• Cardiology
• Biomedical Engineering
• Medical Imaging

Background:

• Noninvasive assessment of myocardial properties and hemodynamics in Fontan patients is challenging.
• Natural shear wave (SW) elastography offers a novel echocardiographic method for evaluating myocardial stiffness using SW velocity.
• High frame rate (HFR) imaging is crucial for detecting these naturally occurring SWs.

Purpose of the Study:

• To measure SW speed in Fontan patients after atrioventricular valve closure (AVVC) and outflow valve closure.
• To compare SW speed in Fontan patients with age-matched healthy volunteers.
• To explore the relationship between SW speed, clinical features, and systemic venous pressures (SVPs).

Main Methods:

• Enrolled 47 Fontan patients (mean age 19 ± 11 years) and collected clinical and echocardiographic data.
• Acquired HFR parasternal long-axis views and SVPs (n=30).
• Processed HFR images offline to extract SW velocities from tissue Doppler acceleration maps.

Main Results:

• Fontan patients exhibited significantly higher average SW speeds than healthy volunteers (5.3 m/s vs 3.0 m/s post-AVVC; 5.1 m/s vs 3.4 m/s post-outflow valve closure; P < 0.001).
• Patients with Fontan circulatory failure showed increased SW speed compared to well-functioning Fontan patients (6.3 m/s vs 4.9 m/s; P = 0.008).
• SW velocity post-AVVC moderately correlated with SVP (r=0.55, P=0.002), outperforming conventional diastolic parameters.

Conclusions:

• Fontan hearts may be stiffer than normal, indicated by elevated SW velocities.
• Increased SW velocities are associated with Fontan circulatory failure.
• SW speed is a potential noninvasive biomarker related to SVP in Fontan patients.