Diastolic Vortex Alterations With Reducing Left Ventricular Volume: An In Vitro Study

Abstract

Despite the large number of studies of intraventricular filling dynamics for potential clinical applications, little is known as to how the diastolic vortex ring properties are altered with reduction in internal volume of the cardiac left ventricle (LV). The latter is of particular importance in LV diastolic dysfunction and in congenital diseases such as hypertrophic cardiomyopathy (HCM), where LV hypertrophy can reduce LV internal volume. We hypothesized that peak circulation and the rate of decay of circulation of the diastolic vortex would be altered with reducing end diastolic volume (EDV) due to increasing confinement. We tested this hypothesis on physical models of normal LV and HCM geometries, under identical prescribed inflow profiles and for multiple EDVs, using time-resolved particle image velocimetry measurements on a left heart simulator. Formation and pinch-off of the vortex ring were nearly unaffected with changes to geometry and EDV. Pinch-off occurred before the end of early filling (E-wave) in all test conditions. Peak circulation of the vortex core near the LV outflow tract increased with lowering EDV and was lowest for the HCM model. The rate of decay of normalized circulation in dimensionless formation time (T*) increased with decreasing EDV. When using a modified version of T* that included average LV cross-sectional area and EDV, normalized circulation of all EDVs collapsed closely in the normal LV model (10% maximum difference between EDVs). Collectively, our results show that LV shape and internal volume play a critical role in diastolic vortex ring dynamics.

Septaly Oriented Mild Aortic Regurgitant Jets Negatively Influence Left Ventricular Blood Flow—Insights From 4D Flow MRI Animal Study

“…Reduced vortex size and delayed vortex formation time was observed in patients and confirmed in models simulating left ventricular hypertrophy (27,28). These findings were attributed to the reduced LV volume not providing sufficient space for proper vortex development, ultimately resulting in increased kinetic energy dissipation (27,28). Hence, extrapolating these findings to our study of healthy porcine hearts, it could be argued that RCC regurgitant jets induced a "fluid dynamic" correlate to reduction of space available for proper diastolic vortex development in hypertrophic left ventricle.…”

“…On the other hand, RCC jets were directed along the septal wall and locally reduced the cross-sectional size of the vortex delaying or even prohibiting vortex formation. Reduced vortex size and delayed vortex formation time was observed in patients and confirmed in models simulating left ventricular hypertrophy (27,28). These findings were attributed to the reduced LV volume not providing sufficient space for proper vortex development, ultimately resulting in increased kinetic energy dissipation (27,28).…”

Left ventricular vortex analysis by high-frame rate blood speckle tracking echocardiography in healthy children and in congenital heart disease

“…This is in accordance with previous biomechanical studies which demonstrated that reducing end-diastolic volumes in a physical left heart simulator led to increased size and dynamics of the LV vortex. [18] In addition, our study found that sphericity index increased with decreasing LVEDVi, suggesting that the vortex became more long-stretched once the ventricle was smaller. Together, these findings suggest that LV shape and internal volume play a critical role in determining vortex dimensions and dynamics, potentially due to the increased confinement associated with smaller intraventricular volumes.…”

Pausing after clap reduces power required to fling wings apart at low Reynolds number

“…The Γ of the LEV or TEV was then calculated by selecting a region of interest (ROI) by drawing a box around a vortex core. A custom MATLAB script was used to automate the process of determining the ROI (Samaee et al 2020). Essentially, we started with a small square box of 2 mm side and compared the Γ value with that of a bigger square box of 5 mm side.…”