Prediction of apical thrombus formation in acute myocardial infarction based on left ventricular spatial flow pattern

Incidence of left ventricular thrombus following STEMI in the modern era via multimodality imaging: A systematic review and meta-analysis

Background

Left ventricular thrombus (LVT) is a significant complication in STEMI. Previous studies were conducted prior to modern timely percutaneous reperfusion networks. Current expert opinion suggests incidence in the current era has decreased. We conducted a systematic review and meta-analysis to better understand the incidence and diagnosis of LVT in patients with STEMI treated with timely percutaneous techniques as assessed by multimodality imaging.

Methods

Cochrane, EMBASE, LILACS, and MEDLINE were searched over the last 10 years only including studies using contemporary techniques. The primary outcome was detection of LVT in patients via echocardiogram with or without contrast or Cardiac MRI (cMRI) following STEMI (both anterior and any territory) treated with PCI. Data was pooled across studies and statistical analysis was conducted via random effects model.

Results

31 studies were included. 18 studies included data on any territory STEMI, totaling 14,172 patients, and an incidence of 5.6% [95% CI 4.3-7.0]. 18 studies were included in analysis for anterior STEMI, totaling 7382 patients and incidence of 12.7% [95% CI 9.8-15.6]. Relative to cMRI as a gold standard, the sensitivity of non-contrast echocardiography to detect LVT was 58.2% [95% CI 46.6-69.2] with a specificity of 97.8% [95% CI 96.3-98.8].

Conclusions

Incidence of LVT in STEMI patients treated with contemporary timely percutaneous revascularization is in keeping with historical data and remains significant, suggesting this remains an ongoing issue for further investigation. Numerically, both cMRI and contrast echo detected more LVT compared to non-contrast echo in any-territory STEMI patients.

Factors predicting resolution of left ventricular thrombus in different time windows after myocardial infarction

BACKGROUND

Left ventricular thrombus (LVT) is a serious complication after myocardial infarction. However, due to its asymptomatic nature, early detection is challenging. We aimed to explore the differences in clinical correlates of LVT found in acute to subacute and chronic phases of myocardial infarction.

METHODS

We collected data from 153 patients who were diagnosed with LVT after myocardial infarction at the Affiliated Hospital of Qingdao University from January 2013 to December 2022. Baseline information, inflammatory markers, transthoracic echocardiograph (TTE) data and other clinical correlates were collected. Patients were categorized into acute to subacute phase group (< 30 days) and chronic phase group (30 days and after) according to the time at which echocardiograph was performed. The resolution of thrombus within 90 days is regarded as the primary endpoint event. We fitted logistic regression models to relating clinical correlates with phase-specific thrombus resolution.

RESULTS

For acute to subacute phase thrombus patients: C-reactive protein levels (OR: 0.95, 95% CI: 0.918-0.983, p = 0.003) were significantly associated with thrombus resolution. For chronic phase thrombus patients: anticoagulant treatment was associated with 5.717-fold odds of thrombus resolution (OR: 5.717, 95% CI: 1.543-21.18, p = 0.009).

CONCLUSIONS

Higher levels of CRP were associated with lower likelihood of LVT resolution in acute phase myocardial infarction; Anticoagulant therapy is still needed for thrombus in the chronic stage of myocardial infarction.

Left ventricular four-dimensional blood flow distribution, energetics, and vorticity in chronic myocardial infarction patients with/without left ventricular thrombus

BACKGROUND

Left ventricular thrombus (LVT) formation is a frequent and serious complication of myocardial infarction (MI). How global LV flow characteristics are related to this phenomenon is yet uncertain. In this study, we investigated LV flow differences using 4D flow cardiovascular magnetic resonance (CMR) between chronic MI patients with LVT [MI-LVT(+)] and without LVT [MI-LVT(-)], and healthy controls.

METHODS

In this prospective cohort study, the 4D flow CMR data were acquired in 19 chronic MI patients (MI-LVT(+), n = 9 and MI-LVT(-), n = 10) and 9 age-matched controls. All included subjects were in sinus rhythm. The following LV flow parameters were obtained: LV flow components (direct, retained, delayed, residual), mean and peak kinetic energy (KE) values (indexed to instantaneous LV volume), mean and peak vorticity values, and diastolic vortex ring properties (position, orientation, shape).

RESULTS

The MI patients demonstrated a significantly larger amount of delayed and residual flow, and a smaller amount of direct flow compared to controls (p = 0.02, p = 0.03, and p < 0.001, respectively). The MI-LVT(+) patients demonstrated numerically increased residual flow and reduced retained and direct flow in comparison to MI-LVT(-) patients. Systolic mean and peak LV blood flow KE values were significantly lower in MI patients compared to controls (p = 0.04, p = 0.03, respectively). Overall, the mean and peak LV vorticity values were significantly lower in MI patients compared to controls. The mean and peak systolic vorticity at the basal level were significantly higher in MI-LVT(+) than in MI-LVT(-) patients (p < 0.01, for both). The vortex ring core during E-wave in MI-LVT(+) group was located in a less tilted orientation to the LV compared to MI-LVT(-) group (p < 0.01).

CONCLUSIONS

Chronic MI patients with LVT express a different distribution of LV flow components, irregular vorticity vector fields, and altered diastolic vortex ring geometric properties as assessed by 4D flow CMR. Larger prospective studies are warranted to further evaluate the significance of these initial observations.

Left Ventricular Thrombus Following Acute Myocardial Infarction: JACC State-of-the-Art Review

The incidence of left ventricular (LV) thrombus following acute myocardial infarction has markedly declined in recent decades caused by advancements in reperfusion and antithrombotic therapies. Despite this, embolic events remain the most feared complication of LV thrombus necessitating systemic anticoagulation. Mechanistically, LV thrombus development depends on Virchow's triad (ie, endothelial injury from myocardial infarction, blood stasis from LV dysfunction, and hypercoagulability triggered by inflammation, with each of these elements representing potential therapeutic targets). Diagnostic modalities include transthoracic echocardiography with or without ultrasound-enhancing agents and cardiac magnetic resonance. Most LV thrombi develop within the first 2 weeks post-acute myocardial infarction, and the role of surveillance imaging appears limited. Vitamin K antagonists remain the mainstay of therapy because the efficacy of direct oral anticoagulants is less well established. Only meager data support the routine use of prophylactic anticoagulation, even in high-risk patients.

Intra-Left Ventricular Hemodynamics Assessed with 4D Flow Magnetic Resonance Imaging in Patients with Left Ventricular Thrombus

Left ventricular thrombus (LVT) has been identified to be crucial in patients with reduced ejection fraction (EF). Three-dimensional cine phase-contrast magnetic resonance imaging (4D flow MRI) can visualize the intra-LV vortex during diastole and quantify the maximum flow velocity (Vmax) at the apex. In this study, we investigated whether the change in the intra-LV vortex was associated with the presence of LVT in patients with cardiac disease.In total, 36 patients (63.5 ± 11.9 years, 28 men, 12/24 with/without LVT) with diffuse LV dysfunction underwent 4D flow MRI. The relative vortex area using streamline images and Vmax of blood flow toward the apex at the apical left ventricle were evaluated. The correlation between the relative vortex area and Vmax was assessed using Pearson's correlation coefficient. The ability to detect LVT was evaluated using the area under the curve (AUC) of the receiver operating characteristic.The relative vortex area was found to be smaller (27 ± 10% versus 45 ± 11%, P = 0.000026), whereas Vmax at the apical left ventricle was lower (19.1 ± 4.4 cm/second versus 27.4 ± 8.9 cm/second, P = 0.0006) in patients with LVT. Vmax at the apical left ventricle demonstrated significant correlations with the relative vortex area (r = 0.43, P = 0.01) and relative transverse length of the vortex (r = 0.45, P = 0.007). The AUC was 0.91 for the relative vortex area, whereas it was 0.80 for Vmax in the apical left ventricle.A smaller LV vortex and lower flow velocity at the LV apex were associated with LVT in patients with reduced EF.

Insights on the left ventricular thrombus in patients with ischemic dilated cardiomyopathy

Background

Left ventricular thrombus (LVT) formation represents a common complication of dilated cardiomyopathy (DCM). LVT is usually underestimated with transthoracic echocardiography (TTE) while cardiac magnetic resonance imaging (CMRI) is promising as an alternative imaging modality for cardiac thrombus detection. The study aims to compare TTE and CMRI in their ability to detect LVT, also, to assess the clinical and imaging parameters to determine variables that may predispose for thrombus formation. The study population includes seventy-six patients with ischemic DCM. They were divided into 2 groups based on the presence of LVT as detected by delayed-enhancement CMRI (DE-CMRI) [Group A included 20 patients with a LVT and Group B included 56 patients without].

Results

All of the current study population had ischemic DCM with left ventricular ejection fraction (LVEF) < 50%. DE-CMR detected thrombus in 20 cases of the studied population that represented group A. From group A, conventional TTE detected LVT only in 8 and cine-CMR detected 13 cases out of the out of 20 cases. The ejection fraction of the left ventricle as measured by functional CMRI was significantly lower in group A (P = 0.045). Interestingly, the myocardial scarring in group A was seen significantly more extensive than in group B (the P value is < 0.00001), paralleling the increased prevalence of thrombus.

Conclusions

DE-CMRI provides superiority for the detection of LVT compared with standard TTE or cine-CMRI and the amount of myocardial scarring detected by DE-CMRI can be considered an independent marker for thrombus presence.

Computational investigation of left ventricular hemodynamics following bioprosthetic aortic and mitral valve replacement

The left ventricle of the heart is a fundamental structure in the human cardiac system that pumps oxygenated blood into the systemic circulation. Several valvular conditions can cause the aortic and mitral valves associated with the left ventricle to become severely diseased and require replacement. However, the clinical outcomes of such operations, specifically the postoperative ventricular hemodynamics of replacing both valves, are not well understood. This work uses computational fluid-structure interaction (FSI) to develop an improved understanding of this effect by modeling a left ventricle with the aortic and mitral valves replaced with bioprostheses. We use a hybrid Arbitrary Lagrangian-Eulerian/immersogeometric framework to accommodate the analysis of cardiac hemodynamics and heart valve structural mechanics in a moving fluid domain. The motion of the endocardium is obtained from a cardiac biomechanics simulation and provided as an input to the proposed numerical framework. The results from the simulations in this work indicate that the replacement of the native mitral valve with a tri-radially symmetric bioprosthesis dramatically changes the ventricular hemodynamics. Most significantly, the vortical motion in the left ventricle is found to reverse direction after mitral valve replacement. This study demonstrates that the proposed computational FSI framework is capable of simulating complex multiphysics problems and can provide an in-depth understanding of the cardiac mechanics.

Association between the E-wave propagation index and left ventricular thrombus formation after ST-elevation myocardial infarction

OBJECTIVE

To explore the association between E-wave propagation index (EPI) as a marker of apical washout and the risk of left ventricular thrombus (LVT) formation in patients with ST-elevation myocardial infarction (STEMI).

METHODS

We performed a post-hoc analysis on 364 prospectively enrolled STEMI patients from a single-center. Non-contrast transthoracic echocardiographic examinations were performed a median of 2 days (IQR:1-3 days) after PCI. The endpoint was LVT formation, identified retrospectively. Univariable and multivariable logistic regression was applied to assess the association between EPI and LVT formation. Multivariable adjustments included LVEF, LAD culprit, prior myocardial infarction, heart rate, and early myocardial relaxation velocity. Area under receiver operating characteristic curves (AUC) was used to assess the diagnostic ability.

RESULTS AND CONCLUSIONS

Among 364 patients, 31 (8.5%) developed LVT. The mean age was 62 years, 75% were men, and mean LVEF was 46%. Patients developing LVT had increased heart rate, lower LVEF, impaired GLS, and more frequently had prior myocardial infarction. Variables associated with low values of EPI included, among others, LVEF, LV aneurysm, and GLS. EPI and LVT formation were significantly associated in the univariable model (OR = 1.87 (1.53-2.28), p < 0.001), and EPI showed an AUC of 0.90. After multivariable adjustments, EPI and LVT formation remained significantly associated (OR = 1.79 (1.42-2.27), p < 0.001). Patients with an EPI < 1.0 had a 23 times higher likelihood of LVT formation (OR = 23.41 (10.06-54.49), p < 0.001). EPI and LVT formation are strongly associated in patients with STEMI, with low values of EPI indicating a markedly increased probability of LVT formation.

A biventricular takotsubo cardiomyopathy complication: large thrombus formation to stroke in 150 min

A 67-year-old postmenopausal African American woman presented with biventricular takotsubo cardiomyopathy (TTC)-evidenced by transthoracic echocardiography (TTE) showing apical akinesis of both left and right ventricles in the absence of obstructive coronary artery disease on left heart catheterisation. On the 4th hospital day, she experienced acute left facial droop, dysarthria and dysphagia. CT of the head showed a wedge infarct of the right middle cerebral artery territory. Cardioembolism was presumed after intracranial and extracranial sources of thromboembolism were ruled out. Intravenous tissue plasminogen activator (tPA) was administered with resolution of symptoms. She was later discharged without neurological deficits. Crucially, repeat TTE after tPA infusion revealed a left ventricular mass concerning for thrombus. TTE 150 min prior to stroke onset was devoid of a mass. This case uniquely illustrates the potential for rapid thrombus formation and embolism in patients with TTC. As such, it emphasises the high index of suspicion required for management of these patients.

Left Ventricular Thrombus in Myocardial Infarction After Successful Primary Percutaneous Coronary Intervention: Prevalence and Predictors-A Middle Eastern Single-Centre Experience

Background

Left ventricular thrombus (LVT) is a well-recognized complication of myocardial infarction that affects patient outcomes and warrants screening.

Methods

This retrospective study included 308 consecutive patients who presented with acute ST-elevation myocardial infarction and were treated with primary percutaneous coronary intervention.

Results

Early screening for LVT by echocardiography and cardiac magnetic resonance revealed the following: LVT (+) group (36 patients [11.7%]) and LVT (−) group (272 patients [88.3%]). The 2 powerful independent variables associated with LVT formation were left anterior descending–related infarct (odds ratio, 10.17; P < 0.0001) and severe left ventricular systolic dysfunction (odds ratio, 8.3; P = 0.0001). The lower the left ventricular ejection fraction, the higher the risk of LVT was. Multivessel coronary artery disease and the type of early invasive strategy (culprit lesion only vs complete revascularization) were not predictive of LVT. The impact of environment (i.e., hot climate, exercise) and dehydration on the risk of LVT formation is uncertain.

Conclusion

Early LVT formation is a frequent complication in acute ST-elevation myocardial infarction despite timely intervention. Its independent predictors are left anterior descending–related infarct and severe left ventricular systolic dysfunction. In patients with multivessel coronary artery disease, there was no significant difference between lesion-only culprits and complete revascularization in reducing the risk of LVT development. Further studies in larger numbers of patients are needed because of the uncertainties regarding the links between the biological effects of the environment and the risk of LVT formation.

Relationship between apical thrombus formation and blood viscosity in acute anterior myocardial infarction patients

Aim: This study sought to investigate the predictive value of whole blood viscosity (WBV) to identify high-risk patients who will develop an apical thrombus during the acute phase of anterior transmural infarction. Materials & methods: Consecutive 1726 patients with first acute anterior myocardial infarction were evaluated. WBV was calculated according to the Simone’s formula. Results: Patients with an apical thrombus had prolonged pain to balloon time, higher rate of post-PCI thrombolysis in myocardial infarction flow ≤1 and significantly higher mean WBV values at both shear rates than those without an apical thrombus. Conclusion: WBV values at both shear rates were found to be significant and independent predictors for early LV apical thrombus formation complicating a first-ever anterior wall myocardial infarction.

Left ventricular thrombus formation in myocardial infarction is associated with altered left ventricular blood flow energetics

Aims

The main aim of this study was to characterize changes in the left ventricular (LV) blood flow kinetic energy (KE) using four-dimensional (4D) flow cardiovascular magnetic resonance imaging (CMR) in patients with myocardial infarction (MI) with/without LV thrombus (LVT).

Methods and results

This is a prospective cohort study of 108 subjects [controls = 40, MI patients without LVT (LVT- = 36), and MI patients with LVT (LVT+ = 32)]. All underwent CMR including whole-heart 4D flow. LV blood flow KE wall calculated using the formula: KE=12 ρblood . Vvoxel . v2, where ρ = density, V = volume, v = velocity, and was indexed to LV end-diastolic volume. Patient with MI had significantly lower LV KE components than controls (P < 0.05). LVT+ and LVT- patients had comparable infarct size and apical regional wall motion score (P > 0.05). The relative drop in A-wave KE from mid-ventricle to apex and the proportion of in-plane KE were higher in patients with LVT+ compared with LVT- (87 ± 9% vs. 78 ± 14%, P = 0.02; 40 ± 5% vs. 36 ± 7%, P = 0.04, respectively). The time difference of peak E-wave KE demonstrated a significant rise between the two groups (LVT-: 38 ± 38 ms vs. LVT+: 62 ± 56 ms, P = 0.04). In logistic-regression, the relative drop in A-wave KE (beta = 11.5, P = 0.002) demonstrated the strongest association with LVT.

Conclusion

Patients with MI have reduced global LV flow KE. Additionally, MI patients with LVT have significantly reduced and delayed wash-in of the LV. The relative drop of distal intra-ventricular A-wave KE, which represents the distal late-diastolic wash-in of the LV, is most strongly associated with the presence of LVT.

Left ventricular outflow obstruction predicts increase in systolic pressure gradients and blood residence time after transcatheter mitral valve replacement

Left ventricular outflow tract (LVOT) obstruction is a relatively common consequence of transcatheter mitral valve replacement (TMVR). Although LVOT obstruction is associated with heart failure and adverse remodelling, its effects upon left ventricular hemodynamics remain poorly characterised. This study uses validated computational models to identify the LVOT obstruction degree that causes significant changes in ventricular hemodynamics after TMVR. Seven TMVR patients underwent personalised flow simulations based on pre-procedural imaging data. Different virtual valve configurations were simulated in each case, for a total of 32 simulations, and the resulting obstruction degree was correlated with pressure gradients and flow residence times. These simulations identified a threshold LVOT obstruction degree of 35%, beyond which significant deterioration of systolic function was observed. The mean increase from baseline (pre-TMVR) in the peak systolic pressure gradient rose from 5.7% to 30.1% above this threshold value. The average blood volume staying inside the ventricle for more than two cycles also increased from 4.4% to 57.5% for obstruction degrees above 35%, while the flow entering and leaving the ventricle within one cycle decreased by 13.9%. These results demonstrate the unique ability of modelling to predict the hemodynamic consequences of TMVR and to assist in the clinical decision-making process.

Optimized Time-Resolved Echo Particle Image Velocimetry– Particle Tracking Velocimetry Measurements Elucidate Blood Flow in Patients With Left Ventricular Thrombus

Contrast ultrasound is a widely used clinical tool to obtain real-time qualitative blood flow assessments in the heart, liver, etc. Echocardiographic particle image velocimetry (echo-PIV) is a technique for obtaining quantitative velocity maps from contrast ultrasound images. However, unlike optical particle image velocimetry (PIV), routine echo images are prone to nonuniform spatiotemporal variations in tracer distribution, making analysis difficult for standard PIV algorithms. This study introduces optimized procedures that integrate image enhancement, PIV, and particle tracking velocimetry (PTV) to obtain reliable time-resolved two-dimensional (2D) velocity distributions. During initial PIV analysis, multiple results are obtained by varying processing parameters. Optimization involving outlier removal and smoothing is used to select the correct vector. These results are used in a multiparameter PTV procedure. To demonstrate their clinical value, the procedures are implemented to obtain velocity and vorticity distributions over multiple cardiac cycles using images acquired from four left ventricular thrombus (LVT) patients. Phase-averaged data elucidate flow structure evolution over the cycle and are used to calculate penetration depth and strength of left ventricular (LV) vortices, as well as apical velocity induced by them. The present data are consistent with previous time-averaged results for the minimum vortex penetration depth associated with LVT occurrence. However, due to decay and fragmentation of LV vortices, as they migrate away from the mitral annulus, in two cases with high penetration, there is still poor washing near the resolved clot throughout the cycle. Hence, direct examination of entire flow evolution may be useful for assessing risk of LVT relapse before prescribing anticoagulants.

Impaired left ventricular diastolic function is related to the formation of left ventricular apical thrombus in patients with acute anterior myocardial infarction

Left ventricular (LV) apical thrombus is a clinically important complication which can cause systemic embolization in patients with anterior acute myocardial infarction (AMI). Systolic dysfunction has been a risk factor for developing LV apical thrombus in AMI patients. However, the role of diastolic dysfunction in the development of LV apical thrombus in these patients is still unknown. We performed this study to evaluate whether diastolic dysfunction can influence the development of LV apical thrombus in anterior AMI patients. We retrospectively analyzed all consecutive anterior AMI patients with available echocardiographic images within 1 month from January 2005 to April 2016. After gathering clinical characteristics from their medical records, systolic and diastolic functions were analyzed from digitally stored echocardiographic images. We included a total of 1045 patients (748 males, mean age 64 ± 12 years) with anterior AMI, and 494 (47%) were diagnosed as STEMI. The incidence of LV apical thrombus was 3.3% (34/1045). The LV apical thrombus group had larger LV diastolic dimension, larger LV diastolic and systolic volumes, and lower LVEF than the no LV thrombus group. The LV apical thrombus group showed higher mitral E velocity over mitral annular E' velocity ratio, an indicator of LV end-diastolic pressure (P < 0.001). In the LV apical thrombus group, the incidence of grade 2 diastolic dysfunction (32 vs 12%, P = 0.001) and grade 3 diastolic dysfunction (26 vs 2%, P < 0.001) were significantly higher than in the no LV apical thrombus group. The presence of more than grade 2 diastolic dysfunction, LVEF and presence of LV apical aneurysm were statistically significant factors associated with LV apical thrombus after the multivariate analysis. In conclusion, along with LV systolic dysfunction and LV apical aneurysm, LV diastolic dysfunction was also related with the presence of LV apical thrombus in patients with anterior AMI.

Prevention of Left Ventricular Thrombus Formation and Systemic Embolism After Anterior Myocardial Infarction: A Systematic Literature Review

BACKGROUND

Anterior myocardial infarction (MI) with apical dysfunction is associated with an increased risk of left ventricular thrombus (LVT) formation and systemic embolism (SE). However, the role for prophylactic anticoagulation in current practice is a matter of debate.

METHODS

We conducted a systematic review of peer-reviewed original articles in either English or French on the benefit of combining anticoagulation with standard therapy for the prevention of LVT/SE after MI by searching PubMed, Ovid/MedLine/Embase, the Cochrane Library, and Google Scholar.

RESULTS

Of 7382 identified records, 14 were retained for analysis. Nine articles addressed anticoagulation for patients not treated with percutaneous coronary intervention (PCI). Another 5 included at least some patients treated with PCI. Only 1 study specifically addressed exclusively a primary PCI population. Some studies showed a benefit for combining anticoagulation with standard therapy in patients not treated with PCI, but results were inconsistent. No evidence of benefit was reported when PCI patients were included and 1 study reported a signal for net harm. There was important interstudy heterogeneity and methodological limitations. Studies were likely individually underpowered.

CONCLUSIONS

The available studies of LVT/SE prevention after MI lacked statistical power and are heterogeneous in terms of treatments, revascularization methods, background medical therapy, and study design. We conclude that there is presently no compelling evidence for or against combining anticoagulation with standard therapy for post-MI patients with apical dysfunction after primary PCI, and inconsistent evidence supporting prophylaxis after thrombolysis. An appropriately powered randomized trial is required to answer this clinically relevant question.

Large In-transient Left Ventricular Thrombus due to Anabolic Steroid-induced Cardiomyopathy

The presence of small or moderate size thrombosis is not uncommon in left ventricle (LV) as results of basic co-moribund disease, but huge LV thrombosis that protrudes to aortic valve in the LV outflow tract (LVOT) tract is an exceptionally rare phenomenon. We report a 34-year-old bodybuilder athlete with cardiomyopathy and massive LV thrombosis. The thrombosis extended to LVOT and protruded through the aortic valve in systole and posed a high risk of systemic emboli. The patient underwent open heart surgery, and the clot was removed. The operation was complicated by low cardiac output syndrome that managed by intra-aortic balloon pump and high dose of inotropic drugs and hemodialysis. The patient died on the 15^th day after surgery with multiorgan failures.

A coupled chemo-fluidic computational model for thrombogenesis in infarcted left ventricles

A coupled chemo-fluidic computational model for investigating flow-mediated thrombogenesis in infarcted left ventricles (LVs) is proposed. LV thrombus (LVT) formation after the acute myocardial infarction (AMI) may lead to thromboembolic events that are associated with high mortality and morbidity, and reliable stratification of LVT risk is the key to managing the treatment of AMI patients. There have been several studies emphasizing the importance of LV blood flow patterns on thrombus formation; however, given the complex interplay between ventricular flow dynamics and biochemistry of thrombogenesis, current understanding is mostly empirical. In the present model, blood flow in the LV is obtained by solving the incompressible Navier-Stokes equations, and this is coupled to the biochemical modeling of the coagulation cascade, platelet activation, and fibrinogen polymerization. The coupled model is used to examine the effect of ventricular flow patterns on thrombogenesis in modeled ventricles. It is expected that the method developed here will enable in-depth studies of thrombogenesis in patient-derived infarcted LV models.

Clinical Characteristics and Risk Factors of Left Ventricular Thrombus after Acute Myocardial Infarction: A Matched Case-control Study

Background:

Left ventricular thrombus (LVT) is reported to be a common complication in acute myocardial infarction (AMI) patients. And it has the potential to cause systemic embolism. This retrospective study was to present the current situation of LVT in clinical practice, as well as to evaluate the clinical characteristics and the risk factors of LVT after AMI.

Methods:

LVT cases (n = 96) were identified from 13,732 AMI (non-ST elevation myocardial infarction was excluded) patients in Fuwai Hospital's electronic medical records system from January 2003 to January 2013. The controls (n = 192) were gender- and age-matched AMI patients without LVT during this period. A conditional logistic regression (fitted by the Cox model) was performed to identify the independent risk factors.

Results:

The incidence of LVT after AMI was 0.7%. Univariate analysis indicated that the anterior myocardial infarction (especially extensive anterior myocardial infarction), lower left ventricular ejection fraction (LVEF), LVEF ≤40%, severe regional wall motion abnormalities (RWMA), pericardial effusion, and left ventricular aneurysm were all related to LVT after AMI. The independent risk factors obtained from the conditional logistic regression analysis were lower LVEF (odds ratio (OR) = 0.891, 95% confidence interval (CI): 0.828–0.960), extensive anterior myocardial infarction (OR = 6.403, 95% CI: 1.769–23.169), severe RWMA (OR = 7.348, 95% CI: 1.323–40.819), and left ventricular aneurysm (OR = 6.955, 95% CI: 1.673–28.921).

Conclusions:

This study indicated that lower LVEF, extensive anterior myocardial infarction, severe RWMA, and left ventricular aneurysm were independent risk factors of LVT after AMI. It also suggested that further efforts are needed for the LVT diagnosis after AMI in clinical practice.

The impact of valve simplifications on left ventricular hemodynamics in a three dimensional simulation based on in vivo MRI data

Left ventricle (LV) fluid dynamics and the function of its valves have a crucial impact on clinical diagnosis, treatment and prosthesis design. In this paper, we simulated left ventricular flow using 3D computational fluid dynamics (CFD) based on geometrical and deformational information obtained from MRI. Time variant smoothed LV shapes were extracted from MR images. Corresponding deformation data was interpolated using a cubic-spline interpolation. To evaluate valve influence on LV flow, we compared two planar valve models: physiologically corrected gradually opening/closing model and a simple on/off model. Endocardial displacement was applied to fluid boundary using fluid-structure interaction (FSI) approach. Arbitrary Lagrangian-Eulerian (ALE) formulation was used for unsteady incompressible viscous Newtonian blood flow in the fluid domain. Comparison of results for LV flow with two valve models demonstrated a clear distinction between pressure distribution, velocity distribution, vortex formation/growth/vanishing and energy dissipation especially in the filling phase. Consequently, LV flow simulation by ignoring geometrical details of valves׳ model may lead to non-realistic results in some aspects.

Doppler vortography: a color Doppler approach to quantification of intraventricular blood flow vortices

We propose a new approach to quantification of intracardiac vorticity based on conventional color Doppler images -Doppler vortography. Doppler vortography relies on the centrosymmetric properties of the vortices. Such properties induce particular symmetries in the Doppler flow data that can be exploited to describe the vortices quantitatively. For this purpose, a kernel filter was developed to derive a parameter, the blood vortex signature (BVS), that allows detection of the main intracardiac vortices and estimation of their core vorticities. The reliability of Doppler vortography was assessed in mock Doppler fields issued from simulations and in vitro data. Doppler vortography was also tested in patients and compared with vector flow mapping by echocardiography. Strong correlations were obtained between Doppler vortography-derived and ground-truth vorticities (in silico: r2 = 0.98, in vitro: r2 = 0.86, in vivo: r2 = 0.89). Our results indicate that Doppler vortography is a potentially promising echocardiographic tool for quantification of vortex flow in the left ventricle.

A new echocardiographic method for identifying vortex flow in the left ventricle: numerical validation

A new mathematical method for estimating velocity vectors from color Doppler datasets is proposed to image blood flow dynamics; this method has been called echodynamography or vector flow mapping (VFM). In this method, the concept of stream function is exploited to expand a 2-D distribution of radial velocities in polar coordinates, observed with color Doppler, to a 2-D distribution of velocity vectors. This study was designed to validate VFM using 3-D numerical flow models. Velocity fields were reconstructed from the virtual color Doppler datasets derived from the models. VFM captured the gross features of flow structures and produced comparable images of the distribution of vorticity, which correlated significantly with the original field (for velocity magnitudes, standard error of estimate = 0.003 to 0.007 m/s; for vorticity, standard error of estimate = 0.35 to 2.01/s). VFM may be sensitive for depicting flow structures derived from color Doppler velocities with reasonable accuracy.

Incidence of early left ventricular thrombus after acute anterior wall myocardial infarction in the primary coronary intervention era

BACKGROUND

Rapid reperfusion has been shown to decrease mortality and improve left ventricular (LV) function. Previous studies have reported that LV thrombus (LVT) is a major complication of ST-segment elevation acute anterior wall myocardial infarction (AMI). There are little data on LVT in the current primary percutaneous coronary intervention (PPCI) era. We sought to demonstrate the incidence of LVT after AMI in patients treated with PPCI compared with those treated with thrombolysis or with conservative management.

METHODS

In a 6-year period, 642 patients with anterior wall AMI and echocardiography were treated with PPCI (n = 297), thrombolysis (n = 128), or conservative treatment (n = 217). Left ventricular thrombus was defined as an echodense mass adjacent to an abnormally contracting myocardial segment.

RESULTS

The rate of LVT among anterior wall AMI was 6.2%. Predictors for LVT were reduced ejection fraction (adjusted relative risk 0.71, 95% CI 0.52-0.96) and severe mitral regurgitation (adjusted relative risk 2.48, 95% CI 1.0-6.44). There was no statistical difference in LVT rate according to treatment: 21 (7.1%) of 297 patients in the PPCI group, 10 (7.8%) of 128 patients in the thrombolytic group, and 9 (4.1%) of 217 patients in the conservative group (P = .28). Those in the thrombolytic group were characterized by shorter duration from symptom onset and were generally also treated with heparin/low-molecular weight heparin.

CONCLUSIONS

This is the largest report to evaluate the incidence of LVT formation after AMI. In the current era of rapid reperfusion by PPCI, the rate of thrombus formation is similar to that reported in the past and not different than for patients currently treated conservatively or with thrombolysis.

Left ventricular mural thrombus after anterior ST-segment-elevation acute myocardial infarction in the era of aggressive reperfusion therapy ??? still a frequent complication

BACKGROUND

Left ventricular mural thrombus (LVMT) is a well-known complication of anterior ST-elevation acute myocardial infraction (AMI). It remains unknown how modern therapies have impacted on its occurrence.

OBJECTIVES

To define the frequency of LVMT among contemporary patients with anterior ST-elevation AMI, the clinical and echocardiographic predictors of LVMT formation, and the intermediate-term outcomes of patients with LVMT.

METHODS

We retrospectively analysed patients (in the years 1997-2002) with a diagnosis of anterior ST-elevation AMI and no prior AMI, and who underwent a thorough echocardiographic assessment within 72 h of admission. Stepwise logistic regression analysis was used to define predictors of LVMT formation. Survival was calculated by the Kaplan-Meier product-limit method.

RESULTS

Of the 153 patients with complete data, LVMT was detected in 36 (23.5%). There were no significant differences in baseline demographic and clinical variables between LVMT and non-LVMT patients, or in treatments (all patients received reperfusion treatment). The mean wall motion score index was higher in LVMT than non-LVMT patients (0.88+/-1.79 versus 0.65+/-0.36, respectively; P=0.01), indicating worse cardiac systolic function. LVMT patients were treated with warfarin for 3-6 months. The incidence of death was similar between the groups (11.1% for LVMT patients versus 12.8% for non-LVMT patients, P=0.79) over a mean follow-up of 71-72 months. The only independent predictor found for LVMT occurrence was worse regional wall motion of the apex (odds ratio, 2.04, 95% confidence interval, 1.39-3.03; P<0.001).

CONCLUSIONS

In the contemporary 'real-world scenario', despite aggressive reperfusion treatment and anti-aggregant use, the incidence of LVMT remained high after anterior ST-elevation AMI. LVMT was not related to increased intermediate-term mortality when patients were treated with warfarin, and the only predictor of LVMT occurrence was regional function of the apex.

Large Atrial Appendage Thrombus in the Presence of Severe Mitral Regurgitation: Contradictory Hemodynamics or Expected Findings

A case of a large left atrial appendage thrombus in the presence of severe mitral regurgitation is presented. The use of transesophageal echocardiography in this setting was not only useful but also crucial despite the low anticipated diagnostic yield given the expected altered left atrial flow dynamics from the turbulent regurgitant lesion. However, additional confounding factors could have acted as potential mechanisms to enhance thrombosis in this setting and consequently are discussed.

Severe mitral regurgitation may prevent mural thrombus formation within the left ventricle with systolic dysfunction

The protective effect of severe mitral regurgitation (MR) against left atrial thrombus formation has been well documented. It was also proposed that severe MR may prevent thrombus formation within the left ventricle (LV) with systolic dysfunction. Therefore, we investigated whether ischemic MR prevents thrombus formation within the LV in patients with systolic dysfunction. The study population was comprised of 1313 patients (1133 males, 180 females, age 56+/-18) with ischaemic LV dysfunction documented by coronary angiography and left ventriculography. None of the patients had a history of chronic anticoagulation. Epicardial coronary arteries were normal in 91 patients, and single-vessel, two-vessel, and triple-vessel disease were detected in 328, 330, and 564 patients, respectively. Left ventricular thrombus and severe MR were detected in 191 (14.5%) and 125 (9.5%) patients, respectively. Overall incidence of LV thrombus was lower in patients with severe MR than in patients without severe MR (4% vs 15.6%, OR: 0.2, P<0.001). Severe MR compared with absence of severe MR was associated with a lower incidence of LV thrombus both in patients with ischemic dilated cardiomyopathy (6.8% vs 34.2%, OR: 0.19, P<0.001), and in patients with aneurysm (3% vs 18%, OR: 0.14, P<0.0001) involving anterolateral, septal and/or apical LV segments. A similar trend without statistical significance was also observed in patients with dyskinesia (4.7% vs 16%, OR: 0.26, P=0.1) related to anterolateral, septal and/or apical LV segments. However, MR had no impact on the incidence of LV thrombus in patients with aneurysm or dyskinesia related to posterior and/or inferior segments (3.7% vs 3%, OR: 1.2, P>0.05). In conclusion, severe MR seems to prevent LV mural thrombus formation in patients with ischemic dilated cardiomyopathy, and in patients with aneurysm related to anterolateral, septal, and/or apical LV segments. This relative risk reduction may be associated with diastolic volume overloading due to severe MR which may overcome stagnation and a procoagulant state within the LV with severe systolic dysfunction.

Relation between early mitral regurgitation and left ventricular thrombus formation after acute myocardial infarction: results of the GISSI-3 echo substudy

OBJECTIVE

To evaluate the prevalence and correlates of left ventricular thrombosis in patients with acute myocardial infarction, and whether the occurrence of early mitral regurgitation has a protective effect against the formation of left ventricular thrombus.

DESIGN AND SETTING

Multicentre clinical trial carried out in 47 Italian coronary care units.

PATIENTS AND METHODS

757 patients from the GISSI-3 echo substudy population with their first acute myocardial infarct were studied by echocardiography at 24-48 hours from symptom onset (S1), at discharge (S2), at six weeks (S3), and at six months (S4). The diagnosis of left ventricular thrombosis was based on the detection of an echo dense mass with defined margins visible throughout the cardiac cycle in at least two orthogonal views.

RESULTS

In 64 patients (8%), left ventricular thrombosis was detected in one or more examinations. Compared with the remaining 693 patients, subjects with left ventricular thrombosis were older (mean (SD) age: 64.6 (13.0) v 59.8 (11.7) years, p < 0.005), and had larger infarcts (extent of wall motion asynergy: 40.9 (11.5)% v 24.9 (14)%, p < 0.001), greater depression of left ventricular ejection fraction at S1 (43.3 (6.9)% v 48.1 (6.8)%, p < 0.001), and greater left ventricular volumes at S1 (end diastolic volume: 87 (22) v 78 (18) ml/m(2), p < 0.001; end systolic volume: 50 (17) v 41 (14) ml/m(2), p < 0.001). The prevalence of moderate to severe mitral regurgitation on colour Doppler at S1 was greater in patients who had left ventricular thrombosis at any time (10.2% v 4.2%, p < 0.05). On stepwise multiple logistic regression analysis the only independent variables related to the presence of left ventricular thrombosis were the extent of wall motion asynergy and anterior site of infarction.

CONCLUSIONS

Left ventricular thrombosis is not reduced, and may even be increased, by early moderate to severe mitral regurgitation after acute myocardial infarction. The only independent determinant of left ventricular thrombosis is the extent of the akinetic-dyskinetic area detected on echocardiography between 24-48 hours from symptom onset.

Left Ventricular Thrombus

Left ventricular thrombus (LVT) is a frequent complication in patients with acute anterior myocardial infarction (MI) and in those with dilated cardiomyopathy (DCM). The clinical importance of LVT lies in its potential to embolize. The current treatment of patients with acute MI centers on reperfusion, and although controversial, the incidence of LVT complicating acute anterior MI is probably reduced when compared with historical controls. Nevertheless, stroke continues to be a clinically important complication of acute MI and is most common in patients with anterior MI, in part secondary to embolization of LVT. Therapeutic anticoagulation during acute MI reduces the incidence of LVT, and long-term anticoagulation has been associated with a reduction in recurrent infarction and ischemic stroke, but carries hemorrhagic risk. Primary treatment strategies for patients with acute MI center on reperfusion therapy followed by antiplatelet agents and pharmacologic blockade of abnormal neurohumoral mechanisms. Strategies to prevent stroke following infarction include risk stratification for development of LVT and embolism. For patients with anterior MI, particularly those with apical akinesis or dyskinesis, therapeutic anticoagulation reduces the number of LVT and cardioembolic strokes. However, the absolute number of ischemic strokes prevented with this strategy may only be marginal, given the anticoagulation risk, particularly if antiplatelet agents are used concurrently. An attractive alternative strategy is echocardiographic evaluation following anterior infarction with therapeutic anticoagulation reserved for those with demonstrable thrombus. The efficacy of this strategy, however, never has been proven in a clinical study. Primary prevention of cardioembolic stroke through therapeutic anticoagulation is controversial in patients with DCM; the greatest benefit would be expected for those with severe left ventricular dysfunction. If LVT is detected during the course of MI or DCM, therapeutic anticoagulation is usually indicated with the expectation that the majority of thrombi will resolve without clinical evidence of systemic embolism. Additional therapeutic intervention is rarely needed.

Power Doppler-derived speckle tracking image of intraventricular flow in patients with anterior myocardial infarction: correlation with left ventricular thrombosis

The abnormal spatial distribution of intraventricular flow is superior to clinical and two-dimensional (2-D) echocardiographic variables in predicting left ventricular thrombosis after myocardial infarction. Echocardiography was prospectively performed in 79 patients within 72 h after anterior wall myocardial infarction onset and repeated before discharge. The apical rotating flow pattern in color flow map was recognized as abnormal. By power Doppler echocardiography, the moving blood could generate speckle tracking images to delineate the intraventricular flow. A swirling flow pattern indicating the compartmentalization of left ventricular blood flow with some blood stagnant in the apical dyssynergic area was identified. The flow pattern shown by the speckle tracking image was superior to the color-flow map in correlating with left ventricular thrombosis. It implicated that the more the detail in which we can describe the blood flow pathway, the more information we can realize.

Defining left ventricular segmental and global function by echocardiographic intraventricular contrast flow patterns

Contrast echocardiography improves left ventricular (LV) endocardial border delineation by enhancement of the blood-tissue interface. In particular, the contrast appearing within the LV chamber exhibits characteristic flow patterns over the cardiac cycle, which may be related to the surrounding myocardial wall motion. To determine the relation between the LV intracavitary contrast flow pattern and surrounding wall motion, we reviewed the contrast-enhanced images of 348 consecutive patients studied at rest. We defined 2 different patterns of intracavitary contrast flow as visualized from apical views: a swift, vertical, and homogeneous flow towards the apex (pattern A), and a distinctly protracted, swirling, and heterogeneous flow (pattern B). Images recorded on videotapes were reviewed and the type of pattern (A or B) was determined within the initial 30 to 45 seconds of contrast appearance in the left ventricle. Contrast flow patterns interpreted by independent reviewer were then compared with the interpretation of the LV segmental and global function in each patient. Results demonstrate that 224 of 245 (91%) patients exhibiting pattern A had normal LV segmental function. Furthermore, all but 1 patient (102 of 103) with pattern B had > or =1 wall motion abnormality (p <0.0001). Contrast flow pattern B was observed irrespective of the location of LV wall motion abnormality. Global LV function was normal in 93% of patients exhibiting pattern A, whereas varying degrees of LV dysfunction were noted in 83% of patients with pattern B (p <0.0001). The presence of mitral regurgitation (p = 0.46), aortic insufficiency (p = 0.066), or mitral inflow Doppler abnormality (p = 0.102) was not significantly associated with either pattern. Thus, during contrast echocardiography, the LV intracavitary contrast flow pattern complements the assessment of global and segmental LV function.

Two-dimensional echocardiographic anatomy of the snake heart (Python molurus bivittatus)

Two-dimensional echocardiography was performed on Burmese pythons (Python molurus bivittatus) to determine an optimal echocardiographic imaging technique for snakes and to describe the echocardiographic anatomy of the snake heart. Five snakes immobilized with tiletamine/zolazepam and maintained on isoflurane in oxygen were imaged in dorsal recumbency. The portion of the snake's body containing the heart was submerged in warm water to reduce the artifact created by air trapped between and under the scales. Imaging in sagittal planes demonstrated the caudal vena cava, sinus venous valve, right atrium, various portions of the ventricle, horizontal septum, the left aortic arch, and pulmonary artery. Transverse imaging depicted the spatial relationship of the left and right aortic arches and pulmonary artery and the horizontal septum. Basic knowledge of cardiac blood flow in the reptile was necessary to understand the echocardiographic anatomy.

Abnormal Inflow Wave Propagation in Patients with Doppler Characteristics of Impaired Left Ventricular Relaxation: Assessment by a Novel Method Through Application of the Range Ambiguity

With application of the range ambiguity, a delay between the flow onset at both the mitral valve and the apex has been shown to be present in patients with a severely dilated and poorly contracting left ventricle and those with acute myocardial infarction with abnormal apical wall motion, but the delay has been absent in normal subjects. Nevertheless, whether there is a delay between the flow onset at both regions in the presence of impaired left ventricular relaxation remains unknown. This study was undertaken to evaluate the left ventricular inflow wave propagation in control subjects and patients with impaired left ventricular relaxation. Eighteen patients with normal systolic function and Doppler characteristics of impaired relaxation of the left ventricle and 17 age- and sex-matched healthy control subjects were included. Range ambiguity was used to simultaneously record the phantom Doppler signals from the mitral valve region and the true ones from the apex. The inflow wave propagation velocity was derived from the inflow wave propagation distance divided by the time between the mitral valve and the apex. There was always some delay between the flow onset at both the mitral valve and the apex in both the controls and the patients (47 +/- 13 msec vs 85 +/- 19 msec, P < 0.001). The inflow wave propagation velocity was 160 +/- 50 cm/sec and 90 +/- 20 cm/sec in the control subjects and the patients, respectively (P < 0.001). Multiple linear regression analyses of the significantly correlated variables stepwisely selected the deceleration time of the E wave (R(2) = 0.53, P < 0.001) and age (R(2) = 0.06, P = 0.039) as the significant determinants of the left ventricular inflow wave propagation velocity. In conclusion, the application of the range ambiguity offers a new method of determining the left ventricular inflow wave propagation velocity, and Doppler characteristics of impaired left ventricular relaxation are associated with a slower inflow wave propagation from the mitral valve to the apex.

Predischarge two-dimensional echocardiographic evaluation of left ventricular thrombosis after acute myocardial infarction in the GISSI-3 study

Left ventricular (LV) thrombosis can be found in patients with acute myocardial infarction (AMI). No wide multicenter trial on AMI has provided information about LV thrombosis until now. The protocol of the GISSI-3 study included the search for the presence of LV thrombosis in patients from 200 coronary care units that did not specifically focus on LV thrombosis. We examined the GISSI-3 database results related to 8,326 patients at low to medium risk for LV thrombi in which a predischarge echocardiogram (9 +/- 5 days) was available. LV thrombosis was found in 427 patients (5.1%): 292 of 2,544 patients (11.5%) with anterior AMI and in 135 of 5,782 patients (2.3%) with AMI in other sites (p <0.0001). The incidence of LV thrombosis was higher in patients with ejection fraction < or = 40% (151 of 1,432 [10.5%] vs 276 of 6,894 [4%]; p <0.0001) both in the total population and in the subgroup with anterior AMI (106 of 597 [17.8%] vs 186 of 1,947 [9.6%]; p <0.0001). Multivariate analysis showed that only the Killip class > I and early intravenous beta-blocker administration were independently associated with higher LV thrombosis risk in the subgroup of patients with anterior AMI (odds ratio 1.75, 95% confidence interval 1.28 to 2.39; odds ratio 1.32, 95% confidence interval 1.02 to 1.72, respectively). In patients with anterior AMI, oral beta-blocker therapy given or not given after early intravenous beta-blocker administration does not influence the occurrence of LV thrombosis. The rate of LV thrombosis was similar in patients treated or not treated with nitrates and lisinopril both in the total population and in patients with anterior and nonanterior AMI. In conclusion, in the GISSI-3 population at low to medium risk for LV thrombi, the highest rate of occurrence of LV thrombosis was found among patients with anterior AMI and an ejection fraction < 40%. Killip class > I and the early intravenous beta-blocker administration were the only variables independently associated with a higher predischarge incidence of LV thrombosis after anterior AMI.

Intracardiac thrombus formation in cardiac impairment: the role of anticoagulant therapy

The presence of intracardiac thrombus has been associated with many diseases and clinical states, although cardiac impairment is commonly also present. Despite this, there continues to be a lack of consensus on which patients with cardiac impairment should have anticoagulant therapy. This review discusses the relationship between thromboembolism and cardiac impairment secondary to ischaemic heart disease, and suggests possible mechanisms, methods of diagnosis and therapeutic strategies for anticoagulation in such patients. In particular, warfarin has been established as thromboprophylaxis in certain subgroups of patients with cardiac impairment secondary to ischaemic heart disease. A large-scale randomised controlled trial in ambulant patients with cardiac impairment to evaluate the effectiveness of anticoagulant therapy and antiplatelet therapy is, however, long overdue.

Three-dimensional reconstruction of the flow in a human left heart by using magnetic resonance phase velocity encoding

Intraventricular flows have been correlated with disease and are of interest to cardiologists as a possible means of diagnosis. This study extends a method that use magnetic resonance (MR) to measure the three-dimensional nature of these flows. Four coplanar, sagittal MR slices were located that spanned the left ventricle of a healthy human. All three velocity components were measured in each slice and 18 phases were obtained per beat. With use of the MR magnitude images, masks were created to isolate the velocity data within the heart. These data were read into the software package, Data Visualizer, and the data from the four slices were aligned so as to reconstruct the three-dimensional volume of the left ventricle and atrium. By representing the velocity in vectorial form, the three-dimensional intraventricular flow field was visualized. This revealed the presence of one large line vortex in the ventricle during late diastole but a more ordered flow during early diastole and systole. In conclusion, the use of MR velocity acquisition is a suitable method to obtain the complex intraventricular flow fields in humans and may lead to a better understanding of the importance of these flows.

A simulation of three-dimensional systolic flow dynamics in a spherical ventricle: effects of abnormal wall motion

Alterations in left ventricle (LV) wall motion induced by ischemia will affect flow dynamics, and these altered flow fields can be used to evaluate LV pumping efficiency. LV chamber flow fields were obtained in this study by solving the discretized three-dimensional Navier-Stokes equations for viscous, incompressible unsteady flow by using the finite analytic method. Several cases of abnormal wall motion (AWM) were simulated by a manipulation of the boundary conditions to produce regions of hypokinesis, akinesis, and dyskinesis. These solutions were used to determine the central ejection region (CER), defined as the region of flow domain in which the obtained velocity field vectors are aligned +/- 3 degrees from the LV long axis. A CER coefficient was computed from information on the location and orientation of the CER within the LV cavity. Contraction of the spherical ventricle produced a vector field that was symmetric with respect to the long axis. For the simulations of AWM, an asymmetrical flow pattern developed, became more pronounced with increasing severity of AWM, and resulted in a shorter CER that shifted toward the ischemic region. The CER coefficients decreased monotonically with increased severity in AWM from 0.948 in the normal case to a low of 0.164 for the most severe case of AWM. The CER coefficient quantitatively displayed the sensitivity of the flow patterns to even moderate degrees of hypokinesis. In addition, visualization of the three-dimensional flow field reinforced the necessity of three-dimensional simulations to capture aspects of the flow that existing methods of two-dimensional flow imaging that use ultrasound may miss.

Doppler left ventricular flow pattern versus conventional predictors of left ventricular thrombus after acute myocardial infarction

OBJECTIVES

The value of Doppler-derived left ventricular spatial flow patterns in predicting left ventricular thrombus formation after myocardial infarction was compared with that of conventional clinical and echocardiographic variables.

BACKGROUND

Assessment of left ventricular thrombosis risk after myocardial infarction is important because of potential embolic sequelae that are reduced by oral anticoagulant agents.

METHODS

Clinical, two-dimensional and Doppler echocardiographic data were prospectively obtained in 104 patients with acute myocardial infarction within 48 h of admission. Ventricular flow was assessed by Doppler echocardiography and considered normal when brisk ventricular inflow with simultaneous onset at the mitral valve and apical levels was present, together with alternating directions of apical flow throughout the cardiac cycle. In addition to normal flow, two abnormal flow patterns were recognized: apical rotating flow and vortex ring formation. Oral anticoagulant agents were prescribed only to patients with abnormal flow at admission. The incidence of left ventricular thrombosis was assessed by echocardiography during 9 months of follow-up.

RESULTS

Abnormal flow pattern had a positive predictive value of 63% and a negative predictive value of 99%. On stepwise logistic regression analysis, only abnormal flow pattern had an independent relation to left ventricular thrombus (odds ratio 92).

CONCLUSIONS

Left ventricular flow pattern derived by Doppler echocardiography soon after admission is superior to conventional clinical and two-dimensional echocardiographic assessment in estimating the risk of left ventricular thrombosis after myocardial infarction.

Prevention of left ventricular thrombus formation during pneumatic pump assist

A postcardiotomy patient with a pneumatic pulsatile pump for left ventricular assist showed a smoke-like swirling echo within the left ventricle during pump assist. The image disappeared partially during intra-aortic balloon pumping, which was performed as usual. Subsequently, three pumps (native left ventricle, pneumatic and intra-aortic balloon) were driven synchronously; that is, the ventricular assist pump ejected the blood in the first half of the diastole of the native heart beat, and the intra-aortic balloon was inflated during the second half. With this bisected diastolic driving, the abnormal echo disappeared completely. The patient died 52 days after operation, but no thromboembolic episode was observed during the course, and no fresh thrombus was found within the left ventricle at autopsy. The bisected diastolic driving method served as an aid to prevent stagnation of blood and thrombus formation within the native left ventricle in this patient with a left ventricular assist device.

Embolic potential, prevention and management of mural thrombus complicating anterior myocardial infarction: a meta-analysis

OBJECTIVES

The management of mural thrombus complicating acute anterior myocardial infarction remains controversial in part because of the small size of studies on this topic. We performed a meta-analysis of published studies to address three questions: 1) What is the embolic risk of mural thrombi after myocardial infarction? 2) What is the impact of systemic anticoagulation in reducing the embolic risk of mural thrombi? 3) What is the impact of systemic anticoagulation, thrombolytic therapy and antiplatelet therapy in preventing mural thrombus formation?

METHODS

Studies were identified by a computerized and manual search and were included if they were published in manuscript form in the English-language literature. Pooling of data was performed by calculating the Mantel-Haenszel odds ratio and an event rate difference by the method of DerSimonian and Laird.

RESULTS

The odds ratio for increased risk of emboli in the presence of echocardiographically demonstrated mural thrombus (11 studies, 856 patients) was 5.45 (95% confidence interval [CI] 3.02 to 9.83), and the event rate difference was 0.09 (95% CI 0.03 to 0.14). The odds ratio of anticoagulation versus no anticoagulation in preventing embolization (seven studies, 270 patients) was 0.14 (95% CI 0.04 to 0.52) with an event rate difference of -0.33 (95% CI -0.50 to -0.16). The odds ratio of anticoagulation versus control in preventing mural thrombus formation (four studies, 307 patients) was 0.32 (95% CI 0.20 to 0.52), and the event rate difference was -0.19 (95% CI -0.09 to -0.28). The odds ratio for thrombolytic therapy in preventing mural thrombus (six studies, 390 patients) was 0.48 (95% CI 0.29 to 0.79) with an event rate difference of -0.16 (95% CI 0.10 to -0.42), whereas for antiplatelet agents (two studies, 112 patients) the odds ratio was 1.43 (95% CI 0.04 to 56.8) with an event rate difference of 0.16 (95% CI -0.20 to 0.52).

CONCLUSIONS

This analysis supports the hypotheses that 1) mural thrombus after myocardial infarction poses a significantly increased risk of embolization, 2) the risk of embolization is reduced by systemic anticoagulation, and 3) anticoagulation can prevent mural thrombus formation. Thrombolytic therapy may prevent mural thrombus formation, but evidence for a similar benefit of antiplatelet therapy is lacking.

Echocardiography in the evaluation of cardiac sources of emboli: the role of transthoracic echocardiography

Cardioembolism is responsible for a significant number of systemic emboli including approximately 15% of all ischemic strokes. Transthoracic echocardiography has contributed to the understanding of cardioembolism and has been used to detect specific and potential cardiac sources of systemic emboli and risk stratify patients with specific clinical findings for subsequent cardiovascular events. Findings from transthoracic echocardiography indicate that stasis is an important prerequisite for intracardiac thrombosis while reversal of stasis and thrombolysis appear operative in embolism of existing thrombus. Transthoracic echocardiography allows a sensitive and specific noninvasive means to detect left ventricular thrombus, valvular vegetation, and intracardiac tumor, lesions that are directly responsible for cardioembolism. Transthoracic echocardiography can also detect lesions that could potentially contribute to cardioembolism but are not specific causes. Examples of these potential lesions include mitral valve prolapse, patent foramen ovale, and interatrial septal aneurysm. Finally, population-based studies and prospective clinical trials have indicated that the results of transthoracic echocardiography have predictive value for subsequent cardiovascular events and hence provide a means for stratification of patients at risk for cardioembolism. The latter is most notable for the group of patients with nonvalvular atrial fibrillation where left ventricular dysfunction and increased left atrial size are independent predictors for subsequent stroke.

Semiautomated method for noise reduction and background phase error correction in MR phase velocity data

Background phase distortion and random noise can adversely affect the quality of magnetic resonance (MR) phase velocity measurements. A semiautomated method has been developed that substantially reduces both effects. To remove the background phase distortion, the following steps were taken: The time standard deviations of the phase velocity images over a cardiac cycle were calculated. Static regions were identified as those in which the standard deviation was low. A flat surface representing an approximation to the background distortion was fitted to the static regions and subtracted from the phase velocity images to give corrected phase images. Random noise was removed by setting to zero those regions in which the standard deviation was high. The technique is demonstrated with a sample set of data in which the in-plane velocities have been measured in an imaging section showing the left ventricular outflow tract of a human left ventricle. The results are presented in vector and contour form, superimposed on the conventional MR angiographic images.

Abnormal intraventricular flow patterns in left ventricular dysfunction determined by color Doppler study

We examined the relation between left ventricular (LV) flow dynamics measured by color Doppler, and either global or regional LV function in 19 normal subjects (group 1), in 55 patients with old myocardial infarction (MI) (29 without [group 2] and 26 with LV aneurysm [group 3]), and in 16 with idiopathic dilated cardiomyopathy (group 4). We calculated by M-mode color Doppler a flow persistence index (FPI) (duration of flow directed in systole toward the apex/LV ejection time). Contrast echocardiography was performed as a control method in 14 patients of the four groups. In normal subjects, rapid systolic inversion of flow toward the aorta was evident (FPI: 0.11 +/- 0.16). In all but one patient in group 2, a similar LV flow pattern was observed, but FPI was greater (0.32 +/- 0.26). In groups 3 and 4, a paradoxical antegrade LV flow pattern was evident during the entire period of systole (FPI: 1.13 +/- 0.42 and 1.28 +/- 0.36, respectively). LV flow patterns were reproduced in echo-contrast studies. FPI was related to LV end-diastolic volume (r = 0.77), end-systolic volume (r = 0.82), and ejection fraction (r = -0.84). However, when data were analyzed separately in the different groups, these correlations were significant only in groups 2 and 3. Paradoxical flow pattern is not peculiar to regional LV dysfunction; it also occurs in global LV dysfunction. This LV flow abnormality may develop after MI even in the absence of severe LV dyssynergy or dilation, and is quantitatively related to the degree of LV dysfunction.

Free vortex ring formation in the left atrium originating in the left auricle

An 80-year-old woman was evaluated by transesophageal echocardiography after coronary artery bypass surgery and subsequent cardioembolic stroke. In addition to spontaneous echo contrast demonstrating a counterclockwise rotating blood flow pattern, we observed free vortex ring formation in the left atrium, originating in the left auricle. To our knowledge, this is the first reported case of abnormal free vortex ring type flow pattern in the left atrium.

Left ventricular blood flow analysis in patients with and without a thrombus after first Q wave acute anterior myocardial infarction: two-dimensional Doppler echocardiographic study

The authors studied 80 consecutive patients with a first Q wave anterior myocardial infarction (MI) by 2-dimensional and color Doppler echocardiography (echo), on day 3 and day 10 after admission, to determine whether left ventricular (LV) blood flow dynamics differ between those who develop LV thrombus and those who do not. With pulsed Doppler echo, peak flow velocities were measured in diastole at the inflow tract, at the apex in diastole and systole, and at the outflow tract in systole. There were 11 patients (14%) who had LV thrombosis on day 3. On day 10, no other patient developed a thrombus. There was no difference in the Doppler flow velocities, except for lower apical diastolic velocities (0.23 +/- 0.04 m/s) (+/- SEM) in patients with thrombus as compared with those without it (0.33 +/- 0.01 m/s) (p less than 0.05). All patients with thrombus had apical dyskinesis and 8 (73%) had an anteroapical aneurysm, while 40 (58%) patients without thrombosis had dyskinesis and 11 (16%) had an aneurysm (p less than 0.01). The ejection fraction was lower (25.4 +/- 3.2%), the wall motion score was higher (10.6 +/- 0.7), and mitral regurgitation was seen more frequently (45%) in those with LV thrombus (respective values in no thrombus group patients: 32.9 +/- 1.4%, 7.6 +/- 0.3, 7%). The authors conclude that LV thrombus prediction is difficult by Doppler flow velocity study, whereas dyskinesis and aneurysmal dilatation of the LV apex is significantly associated with thrombus.