Atrial systole enhances intraventricular filling flow propagation during increasing heart rate

Santhanakrishnan, Arvind; Okafor, Ikechukwu; Kumar, Gautam; Yoganathan, Ajit P.

doi:10.1016/j.jbiomech.2016.01.026

Cited by 4 publications

(3 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Therefore, one could hypothesize that increasing heart-rate in adults would be an effective way to facilitate blood clearing. However, tachycardia increases the velocity of the A-wave at the expense of fusing it with the E-wave (Oniki et al, 1992; Santhanakrishnan et al, 2016; Rossini et al, 2017). Thus, tachycardia and age-related changes in heart-rate induce different effects on blood mixing.…”

Section: Discussionmentioning

confidence: 99%

Age-Dependence of Flow Homeostasis in the Left Ventricle

et al. 2019

View full text Add to dashboard Cite

Background: Intracardiac flow homeostasis requires avoiding blood stasis and platelet activation during its transit through the cardiac chambers. However, the foundations of intraventricular blood washout and its exposure to shear stresses have been poorly addressed. We aimed to characterize and quantify these features in a wide population of healthy subjects and assess the relationships of these indices with age. Methods: We used color-Doppler echocardiography and custom post-processing methods to study 149 healthy volunteers from 26 days to 80 years old. From the intraventricular flow-velocity fields we obtained personalized maps of (1) the residence time of blood in the LV, and (2) the shear index, a metric accounting for the strongest occurrence of shear stresses inside the chamber. From these maps we derived quantitative indices of the overall intraventricular blood washout and shear exposure. We addressed the age-dependence of these indices and analyzed their relationship with age-related changes in filling-flow. Results: The entire intraventricular blood pool was replaced before 8 cycles. Average residence time of blood inside the LV was <3 cycles in all subjects and followed an inverse U-shape relationship with age, increasing from median (IQR) of 1.0 (0.7 to 1.2) cycles in the 1st year of life to 1.8 (1.4–2.2) cycles in young adults (17–30 years old), becoming shorter again thereafter. Shear index showed no relation with age and was bounded around 20 dyn·s/cm 2 . Regions with the longest residence time and highest shear index were identified near the apex. Differences in the degree of apical penetration of the filling waves and the duration of the late-filling phase explained the age-dependence of residence time ( = 0.48, p < 0.001). Conclusions: In average, blood spends 1 to 3 beats inside the LV with very low shear stress rates. The apical region is the most prone to blood stasis, particularly in mid-aged adults. The washout of blood in the normal LV is age-dependent due to physiological changes in the degree of apical penetration of the filling waves.

show abstract

Section: Discussionmentioning

confidence: 99%

Age-Dependence of Flow Homeostasis in the Left Ventricle

et al. 2019

View full text Add to dashboard Cite

show abstract

“…The heart rate might influence the vortex properties by two mechanisms. The first mechanism should be related to the relationship between the heart rate and transmitral filling flow pattern . High heart rate is correlated with increased atrial systolic velocity and leads to a physiological augmentation in transmitral A velocity and reduction in E / A ratio in healthy subjects.…”

Section: Discussionmentioning

confidence: 98%

“…However, the former had a larger end‐diastolic vortex. This might be due to the higher heart rate that is correlated with increased atrial systolic velocity, and the higher monophasic mitral flow velocity. In this case, the fusion of the E and A waves might benefit the formation of the late diastolic vortex and create a favorable condition for effective momentum transfer from LV inflow to outflow.…”

Section: Discussionmentioning

confidence: 99%

Factors influencing the end‐diastolic vortex assessed by using vector flow mapping

Zhang

Ni²,

et al. 2019

Echocardiography

View full text Add to dashboard Cite

Objectives The purpose of this study was to assess the factors influencing the late diastolic vortex in normal and abnormal ventricles. Methods Color Doppler data in left ventricle (LV) were acquired from apical long‐axis view and analyzed using vector flow mapping in 57 patients with coronary artery disease, 57 patients with dilated cardiomyopathy, and 53 healthy volunteers. Results In normals, corrected area and flux of the end‐diastolic vortex were positively correlated with transmitral A velocity and heart rate. Subjects with E/A <1 had higher vortex flux than those with E/A >1. Heart rate was the only independent predictor of corrected vortex area (R2 = .170, P = .004), and transmitral A velocity and heart rate were the independent predictors of corrected vortex flux (R2 = .490, P < .001). Patients with various mitral filling patterns showed significant differences in vortex area and flux. The vortex area and flux were positively correlated with transmitral i velocity and a′. Transmitral A velocity was the only independent predictor of corrected vortex area (R2 = .180, P < .001), while transmitral A velocity, heart rate, LV end‐systolic short diameter, and end‐diastolic long diameter were the independent determinants of corrected vortex flux (R2 = .593, P < .001). Conclusions The end‐diastolic vortex is formed and mainly affected by the late LV filling. The compensatory atrial contraction may enhance the end‐diastolic vortex that facilitates coupling between diastole and systole. LV size can influence the end‐diastolic vortex in patients with LV dysfunction and enlargement.

show abstract

Aortic Regurgitation Generates a Kinematic Obstruction Which Hinders Left Ventricular Filling

et al. 2017

View full text Add to dashboard Cite

An incompetent aortic valve (AV) results in aortic regurgitation (AR), where retrograde flow of blood into the left ventricle (LV) is observed. In this work, we parametrically characterized the detailed changes in intra-ventricular flow during diastole as a result of AR in a physiological in vitro left-heart simulator (LHS). The loss of energy within the LV as the level of AR increased was also assessed. The validated LHS consisted of an optically-clear, flexible wall LV and a modular AV holder. Two-component, planar, digital particle image velocimetry was used to visualize and quantify intra-ventricular flow. A large coherent vortical structure which engulfed the whole LV was observed under control conditions. In the cases with AR, the regurgitant jet was observed to generate a "kinematic obstruction" between the mitral valve and the LV apex, preventing the trans-mitral jet from generating a coherent vortical structure. The regurgitant jet was also observed to impinge on the inferolateral wall of the LV. Energy dissipation rate (EDR) for no, trace, mild, and moderate AR were found to be 1.15, 2.26, 3.56, and 5.99 W/m, respectively. This study has, for the first time, performed an in vitro characterization of intra-ventricular flow in the presence of AR. Mechanistically, the formation of a "kinematic obstruction" appears to be the cause of the increased EDR (a metric quantifiable in vivo) during AR. EDR increases non-linearly with AR fraction and could potentially be used as a metric to grade severity of AR and develop clinical interventional timing strategies for patients.

show abstract

Atrial systole enhances intraventricular filling flow propagation during increasing heart rate

Cited by 4 publications

References 26 publications

Age-Dependence of Flow Homeostasis in the Left Ventricle

Age-Dependence of Flow Homeostasis in the Left Ventricle

Factors influencing the end‐diastolic vortex assessed by using vector flow mapping

Aortic Regurgitation Generates a Kinematic Obstruction Which Hinders Left Ventricular Filling

Contact Info

Product

Resources

About