Transcatheter aortic valve replacement (TAVR) is a growing alternative therapeutic intervention for patients with severe aortic stenosis. However, in a large population of patients, the incomplete seal between the sewing ring of the TAVR and the valve annulus causes a back flow from the aorta to the left ventricle (LV) during diastole. This back flow, known as paravalvular leaks (PVL), has been shown to be an independent predictor of short and long-term mortality following TAVR. As a consequence, accurate quantification of paravavular leaks following TAVR is crucial. However, diagnosis of PVL can be very challenging because to date there is no standardized quantitative methods to assess PVL following TAVR. Currently, native valve regurgitation quantitative grading scheme is being used for evaluating PVL but it has significant limitations that may hinder an accurate diagnosis. Considering the lack of an effective diagnosis method, it is currently difficult to accurately evaluate the PVL severity or to monitor a patient between different follow ups for potential worsening of the PVL severity. Clinical intervention, therefore, strives for advanced imaging techniques that can assess and categorize PVL severity and thus provide a more accurate assessment of risks. Doppler echocardiography is low-cost, widely available and can investigate the heart function in real time. Effective diagnosis of PVL hinges on quantification of the load it imposes on the LV (global effect) and on quantification of blood flow dynamics inside the LV (local effect) as well as the LV outflow tract. Therefore, in this study we aim: (1) to understand the effect of PVL on the LV stroke work and to develop a Doppler echocardiographic method to noninvasively quantify the LV stroke work in patients with TAVR. the LV stroke work is an important index that its accurate estimation can contribute towards improving diagnosis in patients with PVL; (2) to understand the effect of PVL on the vortical structures in the LV and LV outflow tract, to develop a Doppler echocardiographic method to noninvasively investigate vortex dynamics in these regions, and to suggest clinical indices to quantify PVL severity. The developed methods will be validated in vitro and will be evaluated in human subject. These non-invasive methods could provide an unprecedented pathway for evaluating PVL and thereby contributes significantly in improving the diagnosis, risk stratification and clinical decision-making.
|Program type||Postdoctoral Fellowship|
|Effective start/end date||01/01/2016 → 04/30/2017|