Relationship between left ventricular vortex and preejectional flow velocity during isovolumic contraction studied by using vector flow mapping

Diastolic flow in the left ventricular outflow tract - A normal physiological and underappreciated echocardiographic finding

PURPOSE

Diastolic waveforms in the left ventricular outflow tract (LVOT) are commonly observed with Doppler echocardiography. The incidence and mechanism are not well described.

METHODS

This was a retrospective observational study of 186 adult patients, athletes and non-athletes, free of known cardiac disease, presenting for comprehensive transthoracic echocardiography at a research institute. We aimed to evaluate the incidence and echocardiographic associations between LVOT diastolic waveforms.

RESULTS

Left ventricular outflow tract early to mid-diastolic waveforms were present in 100% of athletes and 95% of non-athletes. The LVOT diastolic velocity time integral was larger in athletes than non-athletes with a mean 8.3 cm (95% CI (7.6-8.9)) vs. 5.1 cm (4.4-5.9) (P < 0.0001). Multivariate predictors of this diastolic waveform were age (P = 0.002), slower heart rate (P = 0.035), higher stroke volume (P = 0.003), large mitral E (P = 0.019) and higher E/e' (P = 0.015).

DISCUSSION

An LVOT early diastolic wave is a normal physiological finding. It is related to a flow vortex redirecting diastolic mitral inflow around anterior mitral valve leaflet into the LVOT.

CONCLUSIONS

Early to mid-diastolic LVOT waves are present in almost all patients but more prominent in young athletes than non-athletes. Diastolic LVOT waves increase with younger age, slower heart rate, larger stroke volume and enhanced diastolic function.

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.

Evaluation of left ventricular function by vector flow mapping in females with systemic lupus erythematosus

OBJECTIVES

Compare the intraventricular hemodynamics of 60 females with systemic lupus erythematosus (SLE) and 61 healthy female controls, and determine cardiac function changes using vector flow mapping (VFM).

METHODS

To determine the effect of pulmonary artery pressure changes on left ventricular function, SLE patients were divided into a normal pulmonary artery pressure group (S1, n=24) and an elevated pulmonary artery pressure group (S2, n=36). The energy loss (EL) at each segment of the left ventricular chamber (total, basal, middle, and apical segments) during each period of the cardiac cycle (isovolumic contraction, rapid ejection, rapid filling, reduced filling, atrial contraction) was determined.

RESULTS

The S1 group had significantly more vortices than the control group during the rapid ejection, rapid filling, and atrial contraction periods (p<0.01), and the maximum vortex areas in the S1 and S2 groups were smaller than in the control group during rapid filling and atrial contraction periods (p<0.05). Compared with the control group, the S2 group had greater EL during the systole and diastole periods (p<0.01). EL in the S1 group was significantly greater than in the control group during systole (p<0.01). During the rapid filling period, the EL was positively correlated with septal E' (r=0.784, p<0.01), and during the atrial contraction period, EL was positively correlated with septal E/e' (r=0.812, p<0.01) and A (r=0.715, p<0.01).

CONCLUSION

VFM of patients with SLE can comprehensively, rapidly, and efficiently evaluate changes of myocardial mechanics and intracardiac hemodynamics and provide quantitative analysis of complex intracardiac blood flow. Key points • Vector flow mapping (VFM) is a new non-invasive ultrasound technique that evaluates changes of myocardial mechanics and intracardiac hemodynamics, and provides quantitative analysis of complex intracardiac blood flow. • This study showed that vortex and energy loss may provide more sensitive detection of cardiac dysfunction than conventional echocardiographic indexes in patients with systemic lupus erythematosus.

Characterization of left ventricular cavity flow, wall stress and energy loss by color doppler vector flow mapping in children and adolescents with cardiomyopathy

Background

Vector flow mapping is an emerging echocardiographic method allowing for investigation of intracardiac blood flow mechanics, wall shear stress (WSS), and energy loss (EL). We hypothesized that alterations in EL and WSS will differ among subjects with hypertrophic (HCM), dilated (DCM) cardiomyopathy, and normal controls.

Methods

Echocardiograms were prospectively performed with the ProSound F75CV (Hitachi HealthCare., Tokyo, Japan) on all subjects. 2D color Doppler cine loop images were obtained from apical 5 and the apical long axis views and stored digitally. Measurements were averaged over three cardiac cycles using VFM software to derive flow patterns, WSS, and EL. Standard left ventricular (LV) systolic and diastolic functional parameters were also obtained.

Results

A total of 85 subjects, 22 with HCM (age 18 ± 9 yrs.), 18 DCM (age 18 ± 9 yrs.), and 45 age and gender matched controls were included in the study. Diastolic wall shear stress was found significantly different in HCM (0.004 ± 0.185 N/m²) compared with DCM (0.397 ± 0.301 N/m², P < 0.001), and controls (0.175 ± 0.255 N/m², P = 0.027). Furthermore, indexed systolic EL was found to be significantly elevated in HCM (13.91 ± 13.17 mW/m²/m³) compared with DCM (8.17 ± 9.77 mW/m²/m³, P < 0.001), but not controls (6.45 ± 7.47 mW/m²/m³).

Conclusion

Differences in abnormal ventricular mechanics observed in HCM and DCM are reflected in both EL and WSS, and are suggestive that changes in energetic parameters may represent novel indices of ventricular dysfunction.

Relationship between left ventricular isovolumic relaxation flow patterns and mitral inflow patterns studied by using vector flow mapping

The purpose of this study was to investigate the relationship between isovolumic relaxation flow (IRF) patterns in left ventricle (LV) and mitral inflow patterns. Color Doppler loops were acquired for vector flow mapping in apical long-axis view in 57 patients with coronary artery disease, 31 patients with dilated cardiomyopathy, and 58 healthy controls. IRF patterns were classified into three categories: pattern A, apically directed flow; pattern B, bidirectional flow with small scattered vortices; and pattern C, a large vortex. All normals and patients with normal LV filling (n = 10) showed pattern A. Patients with impaired relaxation consisted of 31 (66%) patients having pattern A, 11 (23%) having pattern B, and 5 (11%) having pattern C. Patients with pseudonormal filling included 4 (31%) patients having pattern A, 7 (54%) having pattern B, and 2 (15%) having pattern C. In patients with restrictive filling, 14 (78%) showed pattern C, 4 (22%) showed pattern B, and no patient showed pattern A. IRF patterns were associated with LV filling patterns (χ² = 52.026, p < 0.001). There are significant relationships between LV filling and IRF patterns. IRF patterns may provide an index for evaluation of LV diastolic function.