The role transmural strain gradient in assessment of functionally single ventricle contractility

Abstract

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): The funds of the Ministry of Education and Science. Background Cardiac imaging in patients with FSV (functionally single ventricle) underwent the Fontan procedure is a challenge. One of the most difficult issue to be resolved in FSV patients is myocardial contractility. Thus, we sought for deformation parameters analysis by STE (Speckle Tracing Echocardiography), for haemodynamic and structural reason. We incorporated a novel STE (Speckle Tracing Echocardiography) parameter– TG (transmural strain gradient) representing the difference in strain between subendocardial and subepicardial layer to assess FSV contractile reserve. The role of TG in assessment of FSV after Fontan palliation has not been evaluated yet. Purpose The study aimed to introduce/evaluate transmural longitudinal strain gradient (TG) at rest and during exercise as marker of FSV contractility and exercise performace. Methods The group of 37 patients with FSV after Fontan palliation were enrolled in our study at least 12 months after Fontan operation and in sinus rhythm on ECG. We performed an transthoracic echocardiography at rest and during exercise on a semi-supine cycle ergometer. The apical-chamber views were registered for subsequent post-processing analysis. Due to heterogeneous FSV morphology and primary defects as well as accompanying intraventricular septum segments malformation in majority of cases, we decided to measure and analyse FSV free wall longitudinal strain only. The values of layer-specific: subendocardial and subepicardial longitudinal free wall systolic strain were assessed and the gradient between them was calculated. The TG at rest and during exercise were compared with the cardiopulmonary exercise test results, NYHA class, FSV systolic function studied by CMR (Cardiac Magnetic Resonance) and NT-proBNP concentration. Results The values of TG at rest and during exercise correlated with peak oxygen uptake during the cardio-pulmonary exercise test (p = ,012 for TG at rest, p = ,031). TG during exercise was negatively correlated with CMR-derived ejection fraction (p = ,031) . There was no relationship between TG and NYHA-class and NT-proBNP. Conclusion(s) TG is a promising parameter for FSV contractility assessment. Our preliminary study suggests that it can complete traditional imaging technics and derived parameters. TG is highly associated to exercise capacity. However, utility of TG requires further investigation.