Left Ventricular Vortex Formation Research Articles

Left ventricular vortex formation time: emerging clinical applications and limitations.

Vortex formation during left ventricular diastolic filling may provide clinically useful insights into cardiac health. In recent years, there has been growing interest in the measurement of vortex formation time (VFT), especially because it is derived noninvasively. There are important applications of VFT in valvular heart disease, athletic physiology, heart failure and hypertrophic cardiomyopathy. The formation of the vortex as fluid propagates into the left ventricle from the left atrium is important for efficient fluid transport. Quantifying VFT may thus help in evaluating and understanding disease and pathophysiological processes.

Age-Related Changes in Left Ventricular Vortex Formation and Flow Energetics.

Analysis of the cardiac vortex has been used for a deeper understanding of the pathophysiology in heart diseases. However, physiological changes of the cardiac vortex with normal aging are incompletely defined. Vector flow mapping (VFM) is a novel echocardiographic technique based on Doppler and speckle tracking for analysis of the cardiac vortex. Transthoracic echocardiography and VFM analysis were performed in 100 healthy adults (33 men; age = 18–67 years). The intracardiac flow was assessed throughout the cardiac cycle. The size (cross-sectional area) and circulation (equivalent to the integral of normal component of vorticity) of the largest vortices in systole (S-vortex), early diastole (E-vortex), and late diastole (A-vortex) were measured. Peak energy loss (EL) was calculated from information of the velocity vector of intracardiac flow in systole and diastole. With normal aging, the circulation (p = 0.049) of the E-vortex decreased, while that of the A-vortex increased (both p < 0.001). E-vortex circulation correlated directly to e’ (p = 0.003), A-vortex circulation correlated directly to A and a’ (both p < 0.001), and S-vortex circulation correlated directly to s’ (p = 0.032). Despite changes in vortex patterns, energy loss was not significantly different in older individuals. Normal aging is associated with altered intracardiac vortex patterns throughout the cardiac cycle, with the late-diastolic A-vortex becoming physiologically more dominant. Maintained energy efficiency accompanies changes in vortex patterns in aging hearts.

Optimal vortex formation time index in mitral valve stenosis.

Left ventricular vortex formation time (VFT) is a novel dimensionless index of flow propagation during left ventricular diastole, which has been demonstrated to be useful in heart failure and cardiomyopathy. In mitral stenosis (MS), flow propagation in the LV may be suboptimal. We studied VFT in varying degrees of MS. Echocardiography was performed on 20 healthy controls and 50 cases of rheumatic MS. Patients with atrial fibrillation, LV ejection fraction < 50% and other valvular heart diseases were excluded. VFT was obtained using the length-to-diameter ratio (L/D), where L is the continuous-wave Doppler velocity time integral stroke distance, divided by D, the mitral leaflet separation index. This was correlated against varying degrees of MS severity, left atrial (LA) volume and function. In controls, VFT was 3.92 ± 2.00 (optimal range) and was higher (suboptimal) with increasing severity of mitral stenosis (4.98 ± 2.43 in mild MS; 7.22 ± 2.98 in moderate MS; 11.55 ± 2.67 in severe MS, p < 0.001). VFT negatively correlated with mitral valve area (R2 = 0.463, p < 0.001) and total LA emptying fraction (R2 = 0.348, p < 0.001), and positively correlated with LA volume index (R2 = 0.440, p < 0.001) and mean transmitral pressure gradient (R2 = 0.336, p < 0.001). More severe MS correlated with suboptimal (higher) VFT. The restricted mitral valve opening may disrupt vortex formation and optimal fluid propagation in the LV. Despite the compensatory increase in LA size with increasingly severe MS, reduced LA function also contributed to the suboptimal LV vortex formation.

An in vitro investigation into the hemodynamic effects of orifice geometry and position on left ventricular vortex formation and turbulence intensity.

In a healthy human cardiac system, a large asymmetric clockwise vortex present in the left ventricle (LV) efficiently diverts the filling jet from the mitral annulus to the left ventricular outflow track. However, prior clinical studies have shown that artificial mitral valve replacement can affect the formation of physiological vortex, resulting in overall flow instability in the LV. Lately, the findings from several recent hemodynamic studies seem to suggest that the native D-shaped mitral annulus might be a crucial factor in the development of this physiological flow pattern, with its inherent flow stability and formation of coherent structures within the LV. This study aims to investigate the effect of orifice shape and its position with respect to the posterior wall of the ventricle on vortical formation and turbulence intensity in the LV, by utilizing four separate orifice configurations within an in vitro left heart simulator. Stereo particle image velocimetry experiments were then carried out to characterize the downstream flow field of each configuration. Our findings demonstrate that the generation of the physiological left ventricular vortical flow was not solely dependent upon the orifice shape but rather the subsequent jet-wall interaction. The distance of the orifice geometric center from the left ventricular posterior wall plays a significant role in this jet-wall interaction, and thus, vortical flow dynamics.

Left ventricular vortex formation in preterm infants assessed by blood speckle imaging.

A vortex is a rotational fluid structure formed by shearing of fluid layers. It forms during diastole in the left ventricle (LV) and helps redirect flow to the LV outflow tract for ejection, optimizing energy conservation. The aim of this study was to demonstrate the feasibility of detecting and analyzing LV vortices using a new ultrasound technique known as blood speckle imaging (BSI). Conventional and BSI parameters were acquired in preterm infants referred for echocardiography. BSI feasibility and reliability were explored using highest frequency settings and optimized Nyquist limits. Vortex area was determined by tracing the outer vortex ring at maximum area. Peak vortex formation time (PVFT) was determined at time of maximum vortex area relative to the R-wave, and vortex duration from frame-by-frame analysis of first appearance to vortex degradation. Left ventricle vortices were detected in 49 of the 50 preterm infants (weight 500-2020g) with excellent intra- and inter-observer reliability. Mean vortex area indexed to LV area was 0.19 (0.08). Peak vortex formation time was at 87 (7)% of the cardiac cycle, and vortex duration lasted 13 (4)% of the cardiac cycle. Vortex area correlated positively with LV length, end-diastolic dimension, end-diastolic volume, mitral annular (R +0.42, +0.50, +0.47, +0.50, all P<0.01), and transmitral Vti (R +0.37, P<0.01). PVFT correlated negatively with E, EA, and Ee' (R -0.42, -0.47, -0.47, all P<0.01). Left ventricle vortex formation can be analyzed with two-dimensional BSI and has the potential to complement existing parameters of cardiac health.

Left ventricular vortex formation time in elite athletes: novel predictor of myocardial performance

BackgroundEfficient transportation of blood through the left ventricle (LV) during diastole depends on vortex formation. Vortex formation time (VFT) can be measured by echocardiography as a dimensionless index. As elite...

Left ventricular vortex formation time in elite athletes.

Vortex formation time (VFT) is a continuous measure of the left ventricular (LV) filling that integrates all phases of diastole. This has been previously studied in patients with heart failure. This study examined the differences in VFT between healthy controls and elite athletes. We compared echocardiographic indices between elite male athletes (n = 41) and age-, weight- and sex-matched sedentary volunteers (n = 22). VFT was obtained using the validated formula: 4 × (1 - β)/π × α3 × LVEF, where β is the fraction of total transmitral diastolic stroke volume contributed by atrial contraction (assessed by time velocity integral of the mitral E- and A-waves) and α is the biplane end-diastolic volume (EDV)1/3 divided by mitral annular diameter during early diastole. Diastolic function was measured by the ratio of mitral peak velocity of early filling (E) to early diastolic mitral annular velocity (e') (E/e' ratio) and the ratio of E to mitral peak velocity of late filling (A) (E/A ratio). The heart rate was lower (63 ± 10 vs. 74 ± 6 beats per minute, p < 0.001) and the LV end diastolic diameter was larger in athletes as compared to controls (56 ± 3 vs. 50 ± 4mm, p < 0.001). The VFT was lower in the sedentary group compared to athletes (3.1 ± 0.4 vs. 4.0 ± 0.8, p < 0.001). Similarly, E/e' was higher in sedentary controls compared to athletes (7.5 ± 1.8 vs 4.2 ± 1.0, p < 0.001). Furthermore, there was a modest correlation between VFT and E/A (r = 0.47, p < 0.001) as well as E/e' (r=-0.33, p = 0.012). In conclusion,the VFT was elevated among elite athletes compared to healthy sedentary controls.

Left ventricular vortex formation is unaffected by diastolic impairment

Normal left ventricular (LV) filling occurs rapidly early in diastole caused by a progressive pressure gradient within the ventricle and with a low left atrial pressure. This normal diastolic function is altered in patients with heart failure. Such impairment of diastolic filling is manifested as an abrupt deceleration of the early filling wave velocity. Although variations within the early filling wave have been observed previously, the underlying hydrodynamic mechanisms are not well understood. Previously, it was proposed that the mitral annulus vortex ring formation time was the total duration of early diastolic filling and provided a measure of the efficiency of diastolic filling. However, we found that the favorable LV pressure difference driving early diastolic filling becomes zero simultaneously with the deceleration of the early filling wave propagation velocity and pinch-off of the LV vortex ring. Thus we calculated the vortex ring formation time using the duration of the early diastolic filling wave from its initiation to the time of the early filling wave propagation velocity deceleration when pinch-off occurs. This formation time does not vary with decreasing intraventricular pressure difference or with degree of diastolic dysfunction. Thus we conclude the vortex ring pinch-off occurs before the completion of early diastole, and its formation time remains invariant to changes of diastolic function.

Assessment of Transmitral Vortex Formation in Patients with Diastolic Dysfunction

Previous experimental models have related transmitral vortex formation to the longitudinal recoil of left ventricle. However, little is known about the relationships among left ventricular (LV) longitudinal relaxation, transmitral filling patterns, and LV vortex formation in clinical settings. The aim of this study was to compare the vortex formation time index among a heterogeneous group of patients with diastolic dysfunction to understand the relationship between transmitral vortex formation and abnormal diastolic filling patterns. Echocardiographic data from 107 subjects were retrospectively evaluated. The study population was categorized into four groups on the basis of transmitral early and late diastolic Doppler filling patterns as normal (n = 45), impaired relaxation (n = 14), pseudonormal (n = 26), and restrictive (n = 22). Vortex formation time was computed from the governing equations based on transmitral flow and ejection fraction. Differences in vortex formation time index were found to be significant among all the studied groups (P < .0001). The trend of vortex formation during a cardiac cycle was compared in normal hearts and those with diastolic dysfunction. Mitral annular velocity (e') was found to decrease significantly (P < .0001) in subjects with abnormal transmitral filling patterns compared with normal subjects. The difference in e' among all the affected groups was not found to be significant (P = .68). The findings of this study suggest that patients with different patterns of transmitral diastolic filling show significant changes in LV vortex formation time despite the absence of significant differences in mitral annulus recoil during diastole.

Abstract 5773: Reduced Left Ventricular Vortex Formation Ability Despite Preserved Ejection Fraction in Low-Flow, Low-Gradient Severe Aortic Stenosis

Background and Aim : Low-flow, low-gradient (LFLG) severe aortic stenosis (AS) despite preserved left ventricular (LV) ejection fraction (EF) has been associated with more advanced stage of the disease, lower cardiac output (CO) and higher systemic afterload. We aim to characterize the LV performance determinants, including its vortex formation (VF) ability. Methods : Echocardiography was performed in 61 consecutive patients with severe AS (aortic valve area index (AVAI) ≤ 0.6 cm 2 /m 2 ) and preserved LVEF (≥ 50%). In addition to biplane LV measurements, AS severity indices and Tei index were measured. Hemodynamic indices (including systemic vascular resistance (SVR) and valvulo-arterial impedance (VAI)) were calculated. VF index (VFI) was obtained from 4 X (1-β)/πX α 3 X LVEF where β is the fraction of total transmitral diastolic stroke volume (SVol) contributed by atrial contraction (assessed by time velocity integral of the mitral E and A waves) and α is the end diastolic volume (EDV) 1/3 divided by mitral annular diameter during early diastole. Patients were categorized by their LV SVol index (SVI). LFLG group consisted of SVI &lt; 45ml/m 2 . Results : Mean VFI was 2.67±1.1; AVAI, 0.50±0.09 cm 2 /m 2 . Though AVAI was slightly lower in LFLG, dimensionless index and aortic valve resistance were similar and associated with no difference in LV mass and volume between the 2 groups. VFI was significantly reduced in the LFLG, 2.37±0.9 vs 3.12±1.3 ( P =0.01), However other LV functional parameters including Tei index and LVEF were similar (Table ). LFLG was associated with higher SVR and VAI (Table ). In LFLG, the only significant correlates of VFI were SVR (r=0.38), VAI (0.37) and stroke work index (0.36); all P s&lt;0.05. VFI did not correlate to these parameters in the non-LFLG group. Conclusion : In LFLG severe AS, increased afterload and suboptimal LV vortex formation ability contribute to lower CO/SV. VFI provides useful insights in understanding this relatively new entity. Comparison of echocardiographic and haemodynamic data in LFLG and non-LFLG groups

Attenuation of Left Ventricular Vortex Formation Ability in Heart Failure

Attenuation of Left Ventricular Vortex Formation Ability in Heart Failure

Intraventricular Pressure Differences

Like all fluids, blood tends to flow from areas of high pressure to low pressure. This seemingly trite observation hides a great deal of sophisticated pathophysiology that we are only beginning to exploit diagnostically and potentially therapeutically. In this issue of Circulation , Yotti and colleagues have exploited a new noninvasive technique to measure the small pressure differences generated within the normal left ventricular outflow tract in systole, demonstrating the utility of such measurements in quantifying ventricular systolic function.1 Because the fluid dynamics concepts behind these methods remain obscure to many cardiologists, it is worth reviewing the theoretical underpinnings in the hope that they will be more widely applied on the basis of articles like those of Yotti et al and others. See p 1771 Cardiologists have become comfortable with the use of the Gorlin equation in the cardiac catheterization laboratory and the simplified Bernoulli equation in the echocardiography laboratory to characterize the severity of valvular stenosis. Both equations are based on the principle of conservation of energy, relating the pressure drop (potential energy) across the valve to the rise in velocity (kinetic energy) as blood rushes through it. Several special circumstances combine to make these simple equations particularly applicable to flow through a restrictive orifice, including lack of a significant friction factor (viscosity) and a lack of pressure recovery as the blood rushes out of the abrupt obstruction. One of the most important simplifications is the absence of a significant “inertial” component to flow through a restrictive orifice. That is, the amount of blood actually moving at high velocity is tiny compared with the volume of the overall column of blood in the left ventricular outflow tract. Thus, very little pressure is expended in getting that small mass moving, and all of the potential energy lost across the …