Left Coronary Artery Flow Research Articles

Diastolic Left Main Coronary Artery Flow Reversal

In patients undergoing percutaneous cardiac interventions, perioperative transesophageal echocardiography is used routinely, often revealing an unusual pathology that was not previously detected with transthoracic echocardiography. In this e-challenge, the authors present a patient undergoing percutaneous transcatheter aortic valve replacement, with preprocedural transesophageal echocardiography revealing an abnormal color Doppler signal near the left main coronary artery during diastole.

Visualization of multiphase pulsatile blood over single phase blood flow in a patient specific stenosed left coronary artery using image processing technique.

Coronary arteries disease has been reported as one of the principal roots of deaths worldwide. The aim of this study is to analyze the multiphase pulsatile blood flow in the left coronary artery tree with stenosis. The 3D left coronary artery model was reconstructed using 2D computerized tomography (CT) scan images. The Red Blood Cell (RBC) and varying hemodynamic parameters for single and multiphase blood flow conditions were analyzed. Results asserted that the multiphase blood flow modeling has a maximum velocity of 1.017 m/s and1.339 m/s at the stenosed region during the systolic and diastolic phases respectively. The increase in Wall Shear Stress (WSS) observed at the stenosed region during the diastole phase as compared during the systolic phase. It was also observed that the highest Oscillatory Shear Index (OSI) regions are found in the downstream area of stenosis and across the bifurcations. The increase in RBCs velocity from 0.45 m/s to 0.6 m/s across the stenosis was also noticed. The computational multiphase blood flow analysis improves the understanding and accuracy of the complex flow conditions of blood elements (RBC and Plasma) and provides the progression of the disease development in the coronary arteries. This study helps to enhance the diagnosis of the blocked (stenosed) arteries more precisely compared to the single-phase blood flow modeling.

Abstract 11145: Biomechanical Engineering Analysis of Leaflet Kinematics and Native Coronary Flow After Valve-Sparing Aortic Root Replacement Using Four Graft Configurations

Introduction: Different ex vivo root biomechanics after valve-sparing aortic root replacement (VSARR) using several graft configurations have been described. The impact of graft choice on each cusp’s kinematics and native coronary flow remains unclear. The objective was to analyze valve kinematics and coronary flow after VSARR using 4 graft configurations in a 3D-printed heart simulator ( Fig A ).[YZ1] Methods: Porcine aortic roots with coronary arteries were explanted (n = 5). Native roots served as controls ( Fig B ). Each sample underwent VSARR using straight graft (SG), Valsalva graft (VG), anti-commissural plication (ACP), and Stanford modification (SMOD) in a random order ( Fig C-G ). Hemodynamics and videometric data were analyzed ( Fig H, I ). Results: SG showed the lowest regurgitant fraction (2.8 ± 1.5 %) compared to control (6.3 ± 3.9 %, p = .0002), VG (12.2 ± 3.6 %, p = .002), ACP (12.9 ± 1.3 %, p = .001), and SMOD (12.2 ± 3.0 %, p = .001, Fig J, K ). The left coronary artery flow was higher in SG (0.68 ± 0.16 L/min) compared to VG (0.55 ± 0.22 L/min, p = 0.05) and SMOD (0.51 ± 0.23 L/min, p = 0.05, Fig L ). The right coronary artery flow was higher in SG (0.20 ± 0.10 L/min) compared to VG (0.07 ± 0.04 L/min, p = 0.04) and SMOD (0.08 ± 0.05 L/min, p = 0.04, Fig M ). SG (26.5 ± 17.6 cm/s) compared to VG (48.3 ± 19.0 cm/s, p = .001) and SMOD (39.5 ± 10.1 cm/s, p = .05) showed lower rapid opening velocity in the left coronary cusp (LCC). SG (8.1 ± 6.2 cm/s) compared to VG (15.0 ± 10.6 cm/s, p = .04) showed lower rapid closing velocity in the right coronary cusp. The VG (17.7 ± 9.7 Hz) had higher flutter frequency in the LCC compared to control (11.9 ± 4.1 Hz, p = .02). The SG (11.9 ± 4.5 dB/Hz) compared to ACP (16.4 ± 4.7 dB/Hz, p = .01) showed lower flutter power in the LCC. Conclusions: Compared to other configurations, SG had the most optimal hemodynamics, native coronary flow, and leaflet kinematics. Further in vivo validation studies should be performed to evaluate flow dynamics in the root and assess for clinical applicability.

Effect of Reynolds number and blood viscosity models on the left coronary artery with multiple stenoses

This study aims to identify the significance of different blood viscosity models along with different Reynolds numbers in the simulation of blood flow in a multi-stenosed Left Coronary Artery (LCA) model. Computational fluid dynamics techniques were implemented to derive the hemodynamic outcomes of the diseased three-dimensional Left Coronary Artery (LCA) models comprising of multiple stenoses. The three-dimensional LCA model was reconstructed using the angiographic images of a healthy person, and three viscosity models, i.e., Carreau, Quemada, and Modified Cross, were considered for carrying out blood flow simulation through it. In this work, the behavior of blood velocity was analyzed by increasing the level of blockage in each of the considered blood viscosity model. It is noticed that the increase in velocity is in proportion with the rise in Reynolds number. This study shows that the Quemada model records the maximum velocity magnitude with the other two rheological models for higher Reynolds numbers. In this work, the area-averaged wall shear stress (AAWSS) along the left anterior descending segment between the areas of double stenoses for different Reynolds numbers was also analyzed. Two peaks of AAWSS were seen for all the Reynolds numbers indicating the two sections of constrictions. The obtained highest peak reflects the primary blockage. Also, an emphasis is laid to prefer the Carreau model over the Quemada and Modified Cross model. This work is purely computational based that might be helpful in providing an insightful understanding of blood flow conduct at the diseased stage in the cardiovascular system.

Prognostic value of Doppler coronary artery assessment in comparison with other echocardiographic prognostic parameters

Abstract Funding Acknowledgements Type of funding sources: None. Background Coronary artery Doppler assessment during routine echocardiography is an established diagnostic tool, that was proved by previous investigators. The prognostic value of impaired coronary flow in left coronary artery was also recently shown in pilot studies [1, 2]. A low feasibility and unknown prognostic value in comparison with other traditional echocardiographic parameters in non-selected population are considered as the main limitations of this method. Aim To evaluate feasibility and the prognostic value of coronary artery ultrasound assessment in a non-selected population in everyday clinical practice in comparison with other echocardiographic parameters. Methods: 581 non-selected patients were screened in prospective cohort study. Left coronary artery flow was scanned in addition to conventional echocardiography. Follow-up period was 12 months. All-cause mortality, myocardial infarction, revascularization, and hospitalization due to heart failure decompensation were defined as major adverse cardiac events (MACE). Results: Feasibility of coronary artery visualization and Doppler assessment was 89.8%. Follow-up was available in 92% of patients; during this period 22 deaths and 1 non-fatal MI occurred, 116 patients had MACE. In univariable analysis age, global longitudinal strain (GLS), left atrium index and maximal coronary velocity were predictors for all-cause death (p < 0.006-0.0001), but ejection fraction was not (p < 0.29). In multivariable analysis maximal coronary velocity (HR: 1.02, 95%, CI: 1.01-1.03, p < 0.0006), age (HR: 1.06, 95%, CI: 1.01-1.11, p < 0.02), and left atrium index (HR: 1.05, 95%, CI: 1.01-1.08, p < 0.007) were independent predictors for all-cause death. Maximal coronary velocity (HR: 1.02, 95%, CI: 1.01-1.03, p < 0.0001), age (HR: 1.03, 95%, CI: 1.01-1.05, p < 0.006), GLS (HR: 0.90, 95%, CI: 0.85-0.96, p < 0.0008) and left atrium index (HR: 1.02, 95%, CI: 1.01-1.04, p < 0.009) were independent predictors for MACE. Conclusion Doppler coronary flow velocity scanning during routine echocardiography is a feasible and valuable tool for assessment of short-term prognosis in non-selected patients. Its short-term prognostic value is better than prognostic value of ejection fraction and global longitudinal strain for the same patients. Abstract Figure. Coronary flow velocity

Investigation of two-way fluid-structure interaction of blood flow in a patient-specific left coronary artery.

The blood flow in the human artery has been a subject of sincere interest due to its prime importance linked with human health. The hemodynamic study has revealed an essential aspect of blood flow that eventually proved to be paramount to make a correct decision to treat patients suffering from cardiac disease. The current study aims to elucidate the two-way fluid-structure interaction (FSI) analysis of the blood flow and the effect of stenosis on hemodynamic parameters. A patient-specific 3D model of the left coronary artery was constructed based on computed tomography (CT) images. The blood is assumed to be incompressible, homogenous, and behaves as Non-Newtonian, while the artery is considered as a nonlinear elastic, anisotropic, and incompressible material. Pulsatile flow conditions were applied at the boundary. Two-way coupled FSI modeling approach was used between fluid and solid domain. The hemodynamic parameters such as the pressure, velocity streamline, and wall shear stress were analyzed in the fluid domain and the solid domain deformation. The simulated results reveal that pressure drop exists in the vicinity of stenosis and a recirculation region after the stenosis. It was noted that stenosis leads to high wall stress. The results also demonstrate an overestimation of wall shear stress and velocity in the rigid wall CFD model compared to the FSI model.

Anomalous Left Coronary Artery from the Pulmonary Artery: The Role of Multimodal Imaging—A Case Report

Anomalous Left Coronary Artery from the Pulmonary Artery (ALCAPA) is a rare coronary artery anomaly which accounts for 0.25–0.5% of all congenital cardiac diseases, where most die within the first year of life. We present a case report of a 50-year-old lady who presented to hospital with persistent palpitations. Her admission electrocardiogram found her to be in Atrial Fibrillation (AF). She was rate-controlled and subsequently discharged. Despite that, she represented with further episodes of AF and was referred for an outpatient transthoracic echocardiogram. This revealed a dilated right coronary artery, retrograde flow in the left coronary artery and collateral flow in the myocardium. To investigate, the patient had undergone further imaging which confirmed the diagnosis. As such, she was later shortlisted for surgical intervention. Conclusively, our case exemplifies the role of multimodal imaging to identify the features of ALCAPA and may be useful for the purposes of surgical intervention.

The effect of patent ductus arteriosus on coronary artery blood flow in premature infants: a prospective observational pilot study

ObjectiveTo compare coronary flows between premature infants with and without hemodynamically significant patent ductus arteriosus (hsPDA) and to determine if coronary flow is influenced by medical PDA treatment.DesignProspective, observational pilot study. Forty-three infants <32 weeks gestation underwent echocardiography when routinely indicated. Study group included infants with hsPDA requiring treatment. Comparison groups included infants with nonsignificant PDA and infants without PDA.ResultsThe study group (n = 13), compared with the comparison groups with nonsignificant PDA (n = 12) and without PDA (n = 18) had higher troponin levels (p = 0.003 and 0.004, respectively). In infants with hsPDA compared with infants with no PDA there was a significant increase in myocardial oxygen demand and decrease in left main coronary artery flow, with nonsignificant increase in cardiac output.ConclusionsDecrease in coronary artery flows and higher troponin values may suggest a “steal effect,” not allowing to meet the elevated myocardial oxygen demand in infants with hsPDA.

Effective myocardial perfusion and concomitant haemodynamic status determine the clinical diversity of anomalous left coronary artery from the pulmonary artery.

Anomalous left coronary artery from the pulmonary artery is a rare congenital heart disease (CHD) with diverse clinical presentations despite the same anatomy. Factors determining this heterogeneous presentation are not well understood. We retrospectively investigated 14 patients (12 females) who underwent surgical repair of anomalous left coronary artery from the pulmonary artery. These patients were divided into three groups based upon the severity of initial presentation: (1) severe, life-threatening condition (n = 5), (2) mild-to-moderate distress (n = 6), and (3) asymptomatic (n = 3). All patients presented with left ventricular dilation and retrograde flow in left coronary artery by echocardiogram. Eight patients in (1) and (2) presented with severe left ventricular dysfunction. All but one showed abnormal ECG consistent with myocardial ischemia or infarction. Asymptomatic patients had preserved left ventricular systolic function despite ischemic findings on ECG. In 13 patients after surgical repair, all but one normalised left ventricular geometry and systolic function, suggesting nearly full myocardial recovery upon improvement of myocardial perfusion; 8 patients had residual echogenic papillary muscle with variable degree of mitral regurgitation. Evidence of myocardial ischemic injury was present in all patients with anomalous left coronary artery from the pulmonary artery regardless of their initial presentation. Retrograde flow in left coronary artery, implying collateral vessel development from right coronary artery to left coronary artery, was noted in all patients, yet only few patients had preserved systolic function at the time of diagnosis. The balance between effective myocardial perfusion and a deleterious fistulous flow provided by these collaterals and the simultaneous haemodynamic status are what determine the clinical diversity of anomalous left coronary artery from the pulmonary artery.

P1486 An unexpected case of paediatric heart failure

Abstract A 9-month-old male presented in heart failure with a 2-day history vomiting that followed a viral upper respiratory tract infection 10 days previously. Echocardiography demonstrated a normally connected heart with a severely dilated and poorly functioning left ventricle with bright mitral valve papillary muscles. It was difficult to demonstrate the origin of the left coronary artery and retrograde flow was seen in the vessel (Fig 1, Panel A). The right coronary artery appeared normal. A gated cardiac CT was performed and showed a normal right coronary origin and no clear connection of the LCA to Ao and there was suspicion of retrograde filling. Images of the left coronary origin did not show clear connection of the LCA to Ao (Fig 1, Panel B). As the case was extremely unusual coronary angiography was performed which confirmed the suspicion of a dominant right coronary system with collateral connection to the left coronary system and retrograde filling and no antegrade filling of the LCA from the Ao (Fig 1, Panel C). This was consistent with atresia of the left coronary ostium, which was confirmed at operation. The left coronary sinus was opened, as was the roof of the left coronary artery and an anastomosis was performed to aorta using an autologous patch. The post operative TOE showed good flow into the LCA (Fig 1, Panel D). There was good and quick post op clinical recovery but the left ventricular function remains still poor at the moment with slow recovery as expected. The cardiac function will be monitored echocardiographically and the reconstructed coronary artery with CT. Abstract P1486 Figure 1

MULTIFIDELITY ESTIMATORS FOR CORONARY CIRCULATION MODELS UNDER CLINICALLY INFORMED DATA UNCERTAINTY

Numerical models are increasingly used for non-invasive diagnosis and treatment planning in coronary artery disease, where service-based technologies have proven successful in identifying hemodynamically significant and hence potentially dangerous vascular anomalies. Despite recent progress towards clinical adoption, many results in the field are still based on a deterministic characterization of blood flow, with no quantitative assessment of the variability of simulation outputs due to uncertainty from multiple sources. In this study, we focus on parameters that are essential to construct accurate patient-specific representations of the coronary circulation, such as aortic pressure waveform, intramyocardial pressure and quantify how their uncertainty affects clinically relevant model outputs. We construct a deformable model of the left coronary artery subject to a prescribed inlet pressure and with open-loop outlet boundary conditions, treating fluid-structure interaction through an Arbitrary-Lagrangian-Eulerian frame of reference. Random input uncertainty is estimated directly from repeated clinical measurements from intra-coronary catheterization and complemented by literature data. We also achieve significant computational cost reductions in uncertainty propagation thanks to multifidelity Monte Carlo estimators of the outputs of interest, leveraging the ability to generate, at practically no cost, one- and zero-dimensional low-fidelity representations of left coronary artery flow, with appropriate boundary conditions. The results demonstrate how the use of multi-fidelity control variate estimators leads to significant reductions in variance and accuracy improvements with respect to traditional Monte-Carlo.

Prognostic value of proximal left coronary artery flow velocity detected by transthoracic Doppler echocardiography

BackgroundLesions in the proximal left coronary artery (LCA) are associated with a poor prognosis compared with other lesional sites. Transthoracic Doppler echocardiography (TTDE) can help to detect proximal LCA flow, and an accelerated coronary flow velocity (CFV) indicates the presence of proximal LCA lesions. This study aimed to investigate the prognostic value of CFV in the proximal LCA measured by TTDE. MethodsWe enrolled 1472 consecutive hemodynamically stable patients with known or suspected heart disease whose CFV was successfully detected using TTDE accompanied by routine echocardiography between 2008 and 2011. The primary outcome was cardiac death (acute myocardial infarction, heart failure, or sudden cardiac death) and patients were followed up over a median of 6.3 years. ResultsOverall, 42 cardiac deaths (3%) were observed. An increased CFV was significantly associated with the outcome in several models based on potential confounders (age, rate pressure product, Framingham Risk Score, diabetes, coronary artery disease, hemoglobin, brain natriuretic peptide, estimated glomerular filtration rate, left ventricular mass, left ventricular ejection fraction, and E/e′). Using a receiver operating characteristic curve analysis, the optimal cut-off value for the CFV to the association of the outcome was 37 cm/s (area under the curve, 0.70; sensitivity, 82%; specificity, 62%). In sequential Cox proportional hazards models, the CFV added incremental prognostic information to the clinical and basic echocardiographic parameters (chi-squared: 110.7 to 146.6, P < 0.01). ConclusionsAn increased CFV in the proximal LCA was associated with cardiac death, incremental to the clinical and basic echocardiographic parameters.

P4340Evaluation of the prognostic value of proximal left coronary artery flow velocity detected by transthoracic Doppler echocardiography

P4340Evaluation of the prognostic value of proximal left coronary artery flow velocity detected by transthoracic Doppler echocardiography

Patient specific 3-d modeling of blood flow in a multi-stenosed left coronary artery.

The current study investigates the effect of multi stenosis on the hemodynamic parameters such as wall pressure, velocity and wall shear stress in the realistic left coronary artery. Patients CT scan image data of normal and diseased left coronary artery was chosen for the reconstruction of 3D coronary artery models. The diseased 3D model of left coronary artery shows a narrowing of more than 70% and 80% of area stenosis (AS) at the left main stem (LMS) and left circumflex (LCX) respectively. The results show that the decrease in pressure was found downstream to the stenosis as compared to the coronary artery without stenosis. The maximum pressure drop was noted across the 80%AS at the left circumflex branch. The recirculation zone was also observed immediate to the stenosis and highest wall shear stress was found across the 80% area stenosis. Our analysis provides an insight into the distribution of wall shear stress and pressure drop, thus improving our understanding on the hemodynamics in realistic coronary artery.

A novel method for left anterior coronary artery flow velocity assessment by transthoracic echocardiography at the peak of a supine bicycle test.

Assessment of coronary flow is only performed during pharmacological tests. Supine bicycle tests permit the visualization of coronary flow assessments during exercise. To assess the parameters of coronary flow in the left anterior descending artery (LAD) during exercise, which could be a sign of significant LAD narrowing. A total of 253 patients were enrolled: Group 1, 186 non-selective participants before undergoing a coronary angiography; and Group 2, 67 controls without coronary artery disease (CAD). All the patients performed a supine bicycle echocardiography test. Coronary flow velocities and coronary flow velocity reserve (CFVR) were measured at the mid-segment of the LAD during exercise. Patients in Group 1 underwent a coronary angiography. In comparison with participants without significant LAD stenosis, patients with LAD lesions had a lower ΔV (16 ± 21 vs. 27 ± 20 cm/s, P < 0.04) and a lower CFVR (1.5 ± 0.8 vs. 2.0 ± 0.6, P < 0.004). In comparison with patients without significant proximal LAD stenosis, the patients with proximal LAD lesions had a lower flow velocity at the peak of exercise (49 ± 32 vs. 61 ± 19 cm/s, P < 0.02), a lower ΔV (13 ± 19 vs. 26 ± 22 cm/s, P < 0.004), and a lower CFVR (1.4 ± 0.6 vs. 1.9 ± 0.7, P < 0.0001). In comparison with the control group, the patients with LAD stenosis had a lower flow velocity at the peak of exercise, a lower ΔV, and a lower CFVR. Non-invasive CFVR measurement in the LAD could provide valuable additional information to a conventional echocardiography exercise test. In routine clinical practice, CFVR is sufficient for a diagnosis of severe stenosis.

Coronary Artery Imaging with Transthoracic Doppler Echocardiography

Coronary artery imaging with transthoracic Doppler echocardiography is a simple and useful technique to diagnose significant coronary artery stenosis. The visualization of mosaic flow in the proximal left coronary artery provides a direct indication of the presence of significant stenosis at the corresponding site during routine echocardiography. Coronary flow velocity reserve (CFVR) has a high diagnostic accuracy and feasibility in detecting the presence of functionally significant coronary stenosis in the left anterior descending coronary artery (LAD) and in the right coronary artery. The measurement of CFVR in the LAD also provides prognostic information in patients with intermediate coronary stenosis. This review summarizes the utility of transthoracic coronary artery imaging.

Color Doppler and pulse wave assessment of flow in anomalous origin of left coronary artery from pulmonary artery: Pre- and post-surgery.

Changes in left coronary artery flow pattern in anomalous left coronary from pulmonary artery can provide valuable insight into pathology and natural history of disease. We wish to discuss a case with pre and post operative left coronary flow pattern with mid term follow up.

The men who picked the truant notes in heart sounds

Since the invention of stethoscope by Rene Laennec, auscultation has become sine qua non of clinical examination, especially for cardiovascular system. Many clinical signs are named after the first describer, as a tribute to their efforts. So is true for cardiac murmurs. Sir Graham Steell was a British cardiologist who described the high pitched diastolic murmur of pulmonary regurgitation. Diastolic murmur of severe aortic regurgitation is named after American physician, Austin Flint, who actually disapproved eponyms. American physician Richard Clarke Cabot and his colleague Locke described early diastolic murmur of severe anemia, which is thought to be due to high flow in left coronary artery. The name of Carey Coomb, a British cardiologist, is associated with mid-systolic murmur of mitral valvulitis in acute rheumatic fever. Left anterior descending arterial stenosis sometimes produces an early diastolic murmur and it was first described by American physician William Dock. The machinery murmur of patent ductus arteriosus was first described by George Alexander Gibson. Key-Hodgkin murmur is the diastolic murmur of aortic regurgitation, named after Thomas Hodgkin and Charles Ashton Key. French pediatrician Henri Louis Roger described the holosystolic murmur of ventricular septal defect and his name is also associated with Maladie de Roger. Sir George Frederic Still, an English paediatrician, whose name is associated with juvenile idiopathic arthritis described the innocent functional murmur mostly heard in children. It was Louis Gallavardin, a French physician, who described the phenomenon of dissociation of musical component and noisy component of aortic stenosis. Though the popularity of such eponyms are on wane due to advent of phonocardiography and ECHO Doppler, one hopes some newer descriptions of murmurs due to changing profile of cardio-vascular diseases will emerge in near future.

Antegrade flow in Anomalous Left Coronary Artery from Pulmonary Artery: Clinical implications

Anomalous origin of the left main coronary artery from the pulmonary artery (ALCAPA) is a rare congenital anomaly that usually presents in childhood. It results in left ventricular (LV) ischemia with resulting LV dysfunction. This ischemia results from retrograde flow into the pulmonary artery which can act as a coronary steal. We here report antegrade flow detected in ALCAPA caused by severe pulmonary hypertension. Anatomic correction of ALCAPA is the preferred surgical option and should be performed as early as possible.

(746) - Non-Ischemic Dilated Cardiomyopathy: Biopsy Proved Markers of Disease Sub-Entities

s S273 Results: CMC p65 NF-κ B deletion promoted maladaptive LVH and accelerated progression towards heart failure, as measured by ejection fraction, LV mass, and lung congestion. Left main coronary artery flow was significantly lower in the knockout mice, but the coronary flow to cardiac output and LV mass ratio was not different between groups. Transgenic mice have higher levels of fibrosis despite similar CMC size. Compared to WT mice, knockouts expressed less HIF-1a, VEGFr2, and more periostin. Whole-field digital microscopy with endothelial-specific immunohistochemistry revealed increased capillary domain areas in KO mice while concurrently demonstrating decreased microvessel density compared to WT. Conclusion: Whereas acute pressure overload promoted compensatory LVH in WT mice, CMC NF-κ B deletion resulted in immediate functional deterioration that was associated with increased fibrosis, decreased HIF expression, and decreased microvessel density. These observations mechanistically implicate NF-κ B and its regulation of hypoxic stress and angiogenesis as an important factor that determines the path, to and between, compensatory hypertrophy and maladaptive HF.