[II-AEPCYIA-6] Natural Shear Wave Elastography in Fontan patients: a new parameter of diastolic function?
Keywords:Fontan, Diastolic function, Natural Shear Wave Elastography
BACKGROUND AND AIM:Non-invasive evaluation of diastolic function in Fontan patients is challenging since conventional parameters are not reliable. Ventricular compliance is known to have a direct impact on ventricular filling and therefore on diastolic function. Chamber compliance, in turn, is directly related to myocardial stiffness. The operational stiffness of the myocardium can non-invasively be assessed using shear wave elastography (SWE), a promising new echocardiographic modality based on measuring the velocity of naturally occurring shear waves using high frame imaging. SWE thus offers a novel tool to study diastolic function. The aims of this study are: to assess feasibility of SWE in Fontan hearts; to document shear wave (SW) speed after atrioventricular valve closure (AVVC); to consider whether SW speed shows correlation with filling pressures.
METHOD:We enrolled 47 Fontan patients (mean age 19 ± 11 years, range 3-46y). High frame rate parasternal long-axis views were acquired using an experimental scanner (1367 ± 270 frame/s). Images were processed offline by extracting tissue Doppler acceleration coded M-modes drawn in the middle of the wall related to the main atrioventricular valve and the outflow valve. We also collected records of pressure in the cavo-pulmonary conduit from recent heart catheterization or from peripheral intra-venous line.
RESULTS:Measurement of SW speed after AVVC was feasible in 97% of patients. Average SW velocity was significatively higher than previously collected data from age-matched healthy volunteers (5.3 ± 1.5 m/s versus 3.54 ± 0.93 m/s, p< 0.001). There was no correlation between SW velocity and age (r=0.092, p=0.54) or association with underlying anatomy (p=0.68). Shear waves velocities after AVVC showed a good correlation with pressure in the cavo-pulmonary conduit (r=0.55, p=0.002), while no other conventional echo parameter showed correlation with filling pressures.
CONCLUSIONS:Our findings show that measurements of natural SW is feasible in Fontan hearts. Their myocardium appears stiffer than normal. Whether this depends on an alteration of intrinsic myocardial properties (fibrosis) and/or on preload conditions, remains to be understood. Our data indicate that shear wave elastography may become a useful tool for non-invasive assessment of diastolic function in univentricular hearts.
METHOD:We enrolled 47 Fontan patients (mean age 19 ± 11 years, range 3-46y). High frame rate parasternal long-axis views were acquired using an experimental scanner (1367 ± 270 frame/s). Images were processed offline by extracting tissue Doppler acceleration coded M-modes drawn in the middle of the wall related to the main atrioventricular valve and the outflow valve. We also collected records of pressure in the cavo-pulmonary conduit from recent heart catheterization or from peripheral intra-venous line.
RESULTS:Measurement of SW speed after AVVC was feasible in 97% of patients. Average SW velocity was significatively higher than previously collected data from age-matched healthy volunteers (5.3 ± 1.5 m/s versus 3.54 ± 0.93 m/s, p< 0.001). There was no correlation between SW velocity and age (r=0.092, p=0.54) or association with underlying anatomy (p=0.68). Shear waves velocities after AVVC showed a good correlation with pressure in the cavo-pulmonary conduit (r=0.55, p=0.002), while no other conventional echo parameter showed correlation with filling pressures.
CONCLUSIONS:Our findings show that measurements of natural SW is feasible in Fontan hearts. Their myocardium appears stiffer than normal. Whether this depends on an alteration of intrinsic myocardial properties (fibrosis) and/or on preload conditions, remains to be understood. Our data indicate that shear wave elastography may become a useful tool for non-invasive assessment of diastolic function in univentricular hearts.