Evaluating the left ventricular hemodynamic phenomena of DDD septum pacemaker implants using vector flow mapping

Evaluation of left ventricular flow field changes after stress in patients with nonobstructive coronary artery disease using ultrasonic flow vector imaging

Purpose

Vector flow mapping and treadmill exercise stress echocardiography were used to evaluate and explore changes in the left ventricular (LV) flow field of patients with nonobstructive coronary artery disease.

Methods

Overall, 34 patients with nonobstructive (<50%) left anterior descending coronary artery stenosis (case group) and 36 patients with no coronary artery stenosis (control group) were included. Apical four-, three-, and two-chamber echocardiographic images were collected at rest and during early recovery from treadmill exercise. LV flow field, vortex area, and circulation (cir) changes were recorded in different phases: isovolumetric systole (S1), rapid ejection (S2), slow ejection (S3), isovolumetric diastole (D1), rapid filling (D2), slow filling (D3), and atrial systole (D4). Intra- and inter-group differences were compared before and after exercise loading.

Results

The control and case groups demonstrated regular trends of eddy current formation and dissipation at rest and under stress. Compared with the control group, the case group had irregular streamline distributions. Abnormal vortices formed in the S1 and D3 apical segments and D1 left ventricular middle segment in the resting group. Compared with the control group, the resting group had decreased left ventricular S1 vortex areas and increased S3 vortex areas. The post-stress D1 and D3 vortex areas and D1 and D2 cir increased. Compared with at rest, after stress, the control group had decreased S1, S3, D2, and D3 vortex areas; increased S2, D1, D3, and D4 cir; and decreased D2 cir. After stress, the case group had decreased S3 and D2 vortex areas, increased D1 vortex areas, and increased S2, D1, D3, and D4 cir (P all < 0.001). Logistic regression and ROC curve analyses show that increased D1 vortex area after stress is an independent risk factor for stenosis in nonobstructive stenosis of coronary arteries (OR: 1.007, 95% CI: 1.005-1.010, P < 0.05). A D1 vortex area cutoff value of 82.26 had an AUC, sensitivity, and specificity of 0.67, 0.655, and 0.726, respectively.

Conclusion

The resting left ventricular flow field changed in patients with nonobstructive left anterior descending coronary artery stenosis. Both groups had more disordered left ventricular blood flow after stress. The increased D1 vortex area after stress is an independent risk factor for mild coronary stenosis and may contribute to the assessment of nonobstructive coronary stenosis. VFM combined with treadmill stress is useful in evaluating left ventricular flow field changes in patients with nonobstructive coronary artery disease, which is valuable in the early evaluation of coronary heart disease.

Speckle tracking imaging evaluation of left ventricular myocardial work comparing right ventricular septal pacing with His-Purkinje system area pacing

Aims

We sought to objectively assess left ventricular myocardial work (MW) parameters after right ventricular septal pacing (VSP) and His-Purkinje system area pacing (HPSAP) procedures.

Materials and methods

Patients undergoing double-chamber pacemaker implantation for III-degree atrioventricular block (III° AVB) were assessed 1 year after implantation. VSP and HPSAP groups (20 and 23 patients, respectively) were compared against 40 healthy age-matched volunteers. Two-dimensional ultrasound speckle tracking imaging was used to obtain the global myocardial work index (GWI), global myocardial work efficiency (GWE), global myocardial constructive work (GCW), global myocardial wasted work (GWW), left ventricular stratified strain, and peak strain dispersion (PSD).

Results

GWI, GWE, and GCW parameters were improved in HPSAP compared to VSP, while GWW was significantly larger in the VSP group compared to the HPSAP group (all p < 0.05). HPSAP outperformed the VSP group in comparisons of global left ventricular longitudinal strain and stratified strain. Compared to controls, the GCW of all segmental myocardium (17/17 segments) in the VSP group was significantly reduced, while 70.59% (12/17 segments) in the HPSAP group was lower than the control group. GCW in the left ventricular segment of the HPSAP group was bigger than the VSP group (29.41%; 5/17 segments) and mainly concentrated in the ventricular septum and inferior wall.

Conclusion

Our findings suggest that HPSAP performance outcomes are improved over VSP after 1 year, especially in left ventricular contractile synchrony, and HPSAP is beneficial to the effective myocardial work of the left ventricle.

Influence of a single hemodialysis on left ventricular energy loss and wall shear stress in patients with uremic cardiomyopathy assessed with vector flow mapping

Background

The influence of hemodialysis (HD) on hydromechanics of the left ventricle has not been reported. This study evaluated the left ventricular summation of energy loss (EL-SUM), average energy loss (EL-AVE), and wall shear stress (WSS) before and after HD using vector flow mapping (VFM) in patients with end-stage renal disease (ESRD).

Methods

We prospectively recruited 40 patients receiving long-term HD and excluded those with structural cardiac disease. Echocardiography was performed before and within 24 hours after HD. Conventional echocardiographic parameters, summation, and average energy loss (EL-SUM, EL-AVE, EL-base, EL-mid and EL-apex), and WSS in each segment were compared.

Results

A total of 40 patients with uremia were recruited. After HD, left ventricular EL-AVE-total, and EL-SUM-total decreased significantly in the early diastolic [29.43 (18.76 to 46.28) vs. 17.70 (10.76 to 95.60) N/(m²·s) and 12 (6 to 17) vs. 5 (3 to 11) e⁻² J; P<0.001, respectively], mid-diastolic [17.07 (10.38 to 24.35) vs. 10.29 (5.86 to 16.30) N/(m²·s) and 7 (3 to 10) vs. 4 (2 to 6) e⁻² J; P<0.001, respectively], and early systolic [17.82 (12.79 to 24.77) vs.14.90 (10.23 to 19.05) N/(m²·s) P=0.011 and 8 (5 to 11) vs. 5 (4 to 8) e⁻² J, P=0.002, respectively] phases. It was revealed that HD did not change EL-AVE-total and EL-SUM-total in the late diastolic and late systolic phases. The EL-AVE decreased after HD in the left ventricular (LV) basal [50.70 (24.19 to 77.92) vs. 26.00 (11.50 to 47.68) N/(m²·s); P<0.001] and mid [15.52 (8.88 to 20.90) vs. 9.47 (6.41 to 14.21) N/(m²·s); P=0.001] segments during the early diastolic phase; in the LV basal [18.64 (10.33 to 29.80) vs. 10.25 (6.98 to 19.43) N/(m²·s); P<0.001), mid (15.70 (9.93 to 23.08) vs. 9.99 (6.03 to 16.25) N/(m²·s); P<0.001), and apical [9.78 (4.06 to 15.77) vs. 4.52 (3.14 to 10.36) N/(m²·s); P=0.001) segments during the mid-diastolic phase; in the LV mid [14.34 (8.34 to 23.88) vs. 9.36 (6.48 to 17.05) N/(m²·s); P=0.013] and apex [11.25 (6.37 to 21.88) vs. 6.60 (5.33 to 12.17) N/(m²·s); P=0.016] segments during the late diastolic phase; and in the apical [10.28 (6.05 to 17.01) vs. 7.59 (3.73 to 13.20) N/(m²·s) P=0.025] segment during the early systolic phase. After HD, WSS significantly reduced in the mid-diastolic [0.51 (0.32 to 0.69) vs. 0.38 (0.30 to 0.46) Pa, P=0.001] and early systolic [0.60 (0.45 to 0.81) vs. 0.57 (0.42 to 0.68) Pa, P=0.029] phases. There was no change in WSS during the early diastolic, late diastolic, and late systolic phases.

Conclusions

After HD, EL and WSS of LV decrease during the systolic and diastolic phases. The VFM can reflect the LV hemodynamics in patients undergoing HD under different fluid loads.

Vector flow mapping: A review from theory to practice

BACKGROUND

The interest in intra-cardiac blood flow analysis is rapidly growing, and it has encouraged the development of different non-invasive imaging techniques. Among these, Vector Flow Mapping (VFM), combing Color-Doppler imaging and speckle tracking data, seems to be a promising approach, feasible in adult and children population.

AIM OF THE REVIEW

The aim of this review is to give a historical perspective on the development of VFM method and a summary of the current algorithms and parameters potentially evaluable. Then, we will present the current state-of-the-art of VFM with an overview of clinical studies and applications of this technique.