On the measurement of the vortex formation time in the left ventricle

Vortex formation during left ventricular (LV) diastole plays a crucial role in cardiac filling. Vortex formation time (VFT), originally developed for piston-cylinder systems, has been adapted for cardiac studies as a potential LV performance metric; however, discrepancies in the literature remain regarding its measurement and clinical utility. This study evaluates these inconsistencies and introduces a new VFT formulation grounded in fluid dynamics, by conceptualizing the diastolic motion of the atrioventricular plane as a piston-cylinder mechanism. Alongside the proposed approach, four existing VFT variations were examined, each incorporating different cardiac parameters. The clinical relevance of these formulations was assessed using cardiac MRI data from 86 participants (32 females), including both healthy individuals and patients with heart failure. Correlations between VFTs and six diastolic function metrics, as well as the sensitivity of each method in distinguishing between health and disease, were evaluated. None of the VFT formulations consistently correlated with all diastolic metrics, though each showed a significant relationship with at least one. Notably, only the introduced piston-based VFT correlated significantly with mitral e' velocity (P < 0.0001) and atrial contraction duration (P < 0.05), suggesting it captures unique aspects of LV mechanics. All VFT formulations yielded lower values in the heart-failure group, with three of the four reliably distinguishing between clinical groups. These findings indicate that while each VFT formulation reflects distinct LV mechanisms and may provide complementary insights into diastolic function, none appear sensitive enough to serve as a standalone, comprehensive diastolic metric.NEW & NOTEWORTHY This study addresses discrepancies in the literature regarding the measurement of vortex formation time (VFT) as an index of diastolic function. We evaluate the clinical relevance of three existing VFT formulations and introduce a novel, fluid dynamics-based method (VFT_piston) that models the left ventricular base as a moving piston. Using healthy and heart-failure participants, we demonstrate that each VFT formulation captures distinct aspects of ventricular mechanics and VFT_piston offers physiologically meaningful correlations with diastolic metrics.