Left Atrium Research Articles

Giant mobile thrombus in left atrium

Giant mobile left atrial thrombus has a rare occurrence. Rheumatic mitral valve stenosis (RMVS), which is frequently seen in developing countries, atrial fibrillation, and left atrial dilatation contribute to faster and higher volume thrombus formation. A 46-year-old female suffering from dyspnea was admitted to the cardiology outpatient. Transthoracic and transesophagial echocardiography confirmed rheumatic mitral stenosis with 3.5x 2.5 cm mobile circulating thrombus in left atrium. The patient underwent successful surgical thrombus removal, prostetic mitral valve replacement, and surgical ligation of the left appendage.

Left Atrial Strain for assessment of left ventricle diastolic dysfunction in acute coronary syndrome patients.

Patients with acute coronary syndrome (ACS) have a high incidence of Left ventricle diastolic dysfunction (DD). Latest algorithms for the assessment of DD lay on 2D parameters and describe a grading to quantify its severity. However, there persists a "gray zone" of values in which DD remains indeterminate. to analyze the diagnostic value of Left atrium strain (LAS) for categorization of LV DD and assessment of LV filling pressures in ACS patients. Cross-sectional study that prospectively evaluated 105 patients presenting ACS with preserved LV ejection fraction (LVEF). Patients were divided in 4 groups according to the DD grade. Mean values of LAS, corresponding to three phases of atrial function: reservoir (LASr), conduit (LAScd) and contraction (LASct), were obtained by speckle-tracking echocardiography. Mean age was 60±10 years, with a gender ratio of 6.14. LASr and LASct were significantly lower according to DD severity (p combined=0.021, p combined=0.034; respectively). E/e' ratio was negatively correlated to LASr (r= - 0.251; p= 0.022) and LASct (r= -0.197; p=0.077). Left atrial volume index (LAVI) was also negatively correlated to LASr (r= -0.294, p= 0.006) and LASct (r= -0.3049, p=0.005). Peak tricuspid regurgitation was negatively correlated to LASr (r=-0.323, p=0.017) and LASct (r=-0.319, p=0.020). Patients presenting elevated LV filling pressures had lower LASr and LASct (p=0.049, p=0.022, respectively) compared to patients witn normal LV filling pressures. ROC curve analysis showed that a LASr < 22% (Se= 75%, Sp= 73%) and a LASct < 13% (Se= 71%, Sp=58%) can increase the likelihood of DD grade II or III by 4.6 (OR= 4.6; 95% CI: 1.31-16.2; p=0.016) and 3.7 (OR= 3.7; 95% CI: 1.06-13.1; p= 0.047), respectively. LAS is a valuable tool, which can be used to categorize DD in ACS patients.

Left Ventricular and Atrial Deformation in Patients with Acute Decompensated Heart Failure: A Pilot Study.

The aims of this study were to compare global longitudinal strain of the left ventricle (LV-GLS) and reservoir strain of the left atrium (R-LAS) values between patients with acute decompensation of chronic heart failure (HF) and a control group. Sixteen patients admitted to our ward for acute decompensation of HF were enrolled in this study. Transthoracic echocardiography (TTE) with two-dimensional speckle-tracking analysis (2D ST) was performed in each patient. The patients were divided into two subgroups according to the value of left ventricular ejection fraction (EF) using a cut-off value of ≤40% to distinguish heart failure with reduced ejection fraction (HFrEF) from heart failure with preserved ejection fraction (HFpEF). The control group consisted of 16 individuals without a history of cardiovascular disease, each of whom underwent 2D ST analysis as well. We found that LV-GLS and R-LAS were significantly lower in both the HFrEF and HFpEF subgroups in comparison with the control group (LV-GLS: -13.4 ± 4.7% vs. -19.7 ± 2.5%, p ˂ 0.05; R-LAS: +12.2 ± 6.9% vs. +40.3 ± 7.4%, p ˂ 0.05). Furthermore, there was a significant difference in LV-GLS (-9.6 ± 3.2% vs. -15.2 ± 4.3%, p ˂ 0.05) but not in R-LAS (+13.7 ± 8.6% vs. +11.4 ± 6.2%) between the HFrEF and HFpEF subgroups. Our study demonstrated a significant difference in LV-GLS and R-LAS in all enrolled HF patients compared to the control group. There was also a significant difference in LV-GLS between the HFrEF and HFpEF subgroups.

Characterization of remodeling processes in the atria of atrioventricular block dogs: Utility as an early-stage atrial fibrillation model

To characterize utility of atrioventricular block (AVB) dogs as atrial fibrillation (AF) model, we studied remodeling processes occurring in their atria in acute (<2 weeks) and chronic (>4 weeks) phases. Fifty beagle dogs were used. Holter electrocardiogram demonstrated that paroxysmal AF occurred immediately after the production of AVB, of which duration tended to be prolonged in chronic phase. Electrophysiological analysis showed that inter-atrial conduction time and duration of burst pacing-induced AF increased in the chronic phase compared with those in the acute phase, but that atrial effective refractory period was hardly altered. Echocardiographic study revealed that diameters of left atrium, right pulmonary vein and inferior vena cava increased similarly in the acute and chronic phases. Histological evaluation indicated that hypertrophy and fibrosis in atrial tissue increased in the chronic phase. Electropharmacological characterization showed that i.v. pilsicainide effectively suppressed burst pacing-induced AF with increasing atrial conduction time and refractoriness of AVB dogs in chronic phase, but that i.v. amiodarone did not exert such electrophysiological effects. Taken together, AVB dogs in chronic phase appear to possess such pathophysiology as developed in the atria of early-stage AF patients, and therefore they can be used to evaluate drug candidates against early-stage AF.

NET burden in left atrial blood is associated with biomarkers of thrombosis and cardiac injury in patients with enlarged left atria.

Emerging data suggest an association between left atrial (LA) enlargement, thrombus formation, and ischemic stroke. However, it is unknown what may mediate such clot formation in LA dysfunction. Neutrophils promote large vessel occlusion and microthrombosis via neutrophil extracellular trap (NET) release, thus lying at the interface of inflammation, thrombosis, and fibrosis. We conducted a prospective all-comers cohort study in patients undergoing catheterization procedures with atrial transseptal access (MitraClip, MC; left atrial appendage closure, LAAC; pulmonary vein ablation, PVA; patent foramen ovale closure, PFO). We measured NETs, cytokines, thrombotic factors, and cardiac injury markers in paired blood samples collected from peripheral blood and within the left atrium. We correlated these biomarkers with echocardiographic measures of LA structure and function (including left atrial volume index, LAVI). Data were analyzed by procedure type, and stratified by LAVI or atrial fibrillation (AF) status. We enrolled 70 patients (mean age 64years, 53% women). NETs, but not other markers, were elevated in LA compared to peripheral blood samples. Most thrombotic, inflammatory, and cardiac damage markers were elevated in LAs from MC or LAAC compared to PFO patients. Overall, NET biomarkers positively correlated with VWF, LAVI, and markers of cardiac injury and negatively with ADAMTS13 activity. LA enlargement and the presence of AF similarly stratified patients based on thromboinflammation measurements, but this was not limited to AF at the time of sample collection. Elevated NETs and VWF in patients with enlarged LA or AF suggest enhanced thromboinflammation within the LA.

The Left Atrium Is a Window to the Outcomes of Patients With Atrial Fibrillation

The Left Atrium Is a Window to the Outcomes of Patients With Atrial Fibrillation

Feasibility of Auto-Quantified Epicardial Adipose Tissue in Predicting Atrial Fibrillation Recurrence After Catheter Ablation.

The aim of this study was to build an auto-segmented artificial intelligence model of the atria and epicardial adipose tissue (EAT) on computed tomography (CT) images, and examine the prognostic significance of auto-quantified left atrium (LA) and EAT volumes for AF.Methods and Results: This retrospective study included 334 patients with AF who were referred for catheter ablation (CA) between 2015 and 2017. Atria and EAT volumes were auto-quantified using a pre-trained 3-dimensional (3D) U-Net model from pre-ablation CT images. After adjusting for factors associated with AF, Cox regression analysis was used to examine predictors of AF recurrence. The mean (±SD) age of patients was 56±11 years; 251 (75%) were men, and 79 (24%) had non-paroxysmal AF. Over 2 years of follow-up, 139 (42%) patients experienced recurrence. Diabetes, non-paroxysmal AF, non-pulmonary vein triggers, mitral line ablation, and larger LA, right atrium, and EAT volume indices were linked to increased hazards of AF recurrence. After multivariate adjustment, non-paroxysmal AF (hazard ratio [HR] 0.6; 95% confidence interval [CI] 0.4-0.8; P=0.003) and larger LA-EAT volume index (HR 1.1; 95% CI 1.0-1.2; P=0.009) remained independent predictors of AF recurrence. LA-EAT volume measured using the auto-quantified 3D U-Net model is feasible for predicting AF recurrence after CA, regardless of AF type.

Extremely Rare Case of Primary Intimal Sarcoma of the Left Atrium Diagnosed During an Examination for Cerebral Hemorrhage in a 24-Year-Old Woman.

Extremely Rare Case of Primary Intimal Sarcoma of the Left Atrium Diagnosed During an Examination for Cerebral Hemorrhage in a 24-Year-Old Woman.

Efficacy of a Surgical Cardiac Ablation Clamp using Nanosecond Pulsed Electric Fields: An Acute Porcine Model

ObjectiveThis study examined the effectiveness of a recently developed non-thermal technology, nanosecond pulse field ablation (nsPFA), for surgical ablation of the atria in a beating heart porcine model. MethodsSix pigs underwent sternotomy and ablation using an nsPFA parallel clamp. The ablation electrodes (53 mm long) were embedded in the jaws of the clamp. Nine lesions per pig were created in locations chosen to be representative of the Cox-Maze procedure. Four lesions were intended to electrically isolate parts of the atrium: the right atrial appendage, left atrial appendage, right pulmonary veins, and left pulmonary veins. For these lesions, exit block testing was performed both after ablation and before euthanasia; the time between the two tests was 3.3±0.5 hours (range 2 to 4 hours). Using purse string sutures, five more lesions were created up to the superior vena cava, down to the inferior vena cava, across the right atrial free wall, and at two distinct locations on the left atrial free wall. The clamp delivered a train of nanosecond duration pulses, with a total duration of 2.5 s, independent of tissue thickness. The heart tissue was stained with 1% triphenyltetrazolium chloride (TTC) after a dwelling period of two hours. Subsequently, each lesion was cross sectioned at 5 mm intervals to assess the ablation depth and transmurality. In some sections, transmurality could not be established on the basis of TTC staining alone; for these lesions, Gomori-trichrome stains were used, and the histological sections were evaluated for transmurality. ResultsThe ablation time was 2.5 seconds per lesion, for a total of only 22.5 seconds ablation time to create 9 lesions. A total of 53 lesions were created, resulting in 388 separate histological sections. Transmurality was established in 386 sections (99.5%). Mean tissue thickness was 3.1±1.5 mm (range of 0.2 mm to 8.6 mm). Exit block was confirmed in 23 of the 24 lesions (96%) post-ablation and 23/24 (96%) pre-euthanasia. Over the course of the procedure, neither pulse-induced arrhythmias nor any other complications were noted. ConclusionsThe novel nsPFA clamp device was effective in creating acute conduction block and transmural lesions in both the right and left atria in an acute porcine model. This non-thermal energy source has great potential to both shorten procedural time and enable effective ablation in the beating heart.

The Association between Echocardiographic Parameters of Heart Failure with Preserved Ejection Fraction and Fluid Status Biomarkers in Hemodialysis Patients

Overhydration and cardiac function abnormalities are common in hemodialysis patients. The association of N-terminal prohormone for brain natriuretic peptide (NT-proBNP) and other fluid status biomarkers with echocardiographic parameters of heart failure with preserved ejection fraction (HFpEF) is scarcely investigated in this population. A total of 100 separate measurements performed in 50 dialysis patients (29 male, aged 60 ± 17 years) in NYHA class II/II and preserved left ventricle ejection fraction were analyzed. Plasma levels of NT-proBNP, mid-regional prohormone for atrial natriuretic peptide (MR-proANP) and copeptin (CPP) were measured. The E/e’ ratio as an index of HFpEF and other echocardiographic parameters were calculated. An E/e’ ratio &gt;9 was associated with higher median right ventricular systolic pressure (RVSP) and LVMI values. Left atrium volume index (LAVI) as well as NT-proBNP and MR-proANP, but not CPP levels were significantly higher in this group. In a stepwise multivariate analysis, only CPP and IL-6 levels were found to be independently associated with the E/e’ ratio in the study group, whereas NT-proBNP and MR-proANP were associated only with left heart structure parameters and LVEF. Of the analyzed biomarkers, only the CPP level was found to be independently associated with the E/e’ ratio in maintenance hemodialysis patients.

Efficiency and feasibility of semi-automated software for measuring left atrial volume in routine echocardiography in a pediatric population.

The traditional method for measuring left atrial volume (LAV) involves manual tracing. Recently, semi-automated techniques for measuring LAV, based on 2D speckle tracking echocardiography (STE) and 3D echocardiography (3DE), have become commercially available. This study aimed to investigate the efficiency and feasibility of these semi-automated software methods for LAV measurement in pediatric patients. We analyzed 207 pediatric patients with 2D and 3D echocardiographic images of the left atrium. The maximum LAV was measured using three techniques: (1) manual tracing, (2) STE-based semi-automated measurement, and (3) 3DE-based semi-automated measurement. We compared both LAV and the time required for LAV measurement among these three techniques. Intra- and inter-observer reproducibility of the LAV measurements was assessed using the intraclass correlation (ICC). There was no difference in the LAV between the manual tracing and the STE-based method, but the LAV measured by 3DE-based method was slightly smaller than manual tracing. The measurement time was 32.6 ± 3.5, 53.8 ± 10.8, and 33.8 ± 13.0s for manual tracing, STE-based, and 3DE-based techniques, respectively. There was no difference the time for LAV measurement between the manual tracing and the 3D-based technique. The agreement and ICC for intra-observer reproducibility was similar across all three techniques, but inter-observer reproducibility was superior with the 3DE-based technique. Although the maximum LAV obtained through the 3DE-based techniques was slightly smaller compared with the traditional manual tracing method, the 3DE-based technique is anticipated to be integrated into routine examinations owing to its short measurement time and superior reproducibility.

Impact of commissural calcification on clinical outcome of percutaneous balloon mitral valvuloplasty; a retrospective cohort study of 876 patients

BackgroundPercutaneous balloon mitral valvuloplasty (PBMV) is the ACC/AHA class I recommendation for treating symptomatic rheumatic mitral stenosis with suitable valve morphology, less than moderate MR and absence of left atrium clot. The mitral valve restenosis and significant mitral regurgitation (MR) are known adverse outcomes of PBMV. This study aimed to evaluate the outcomes of PBMV in patients with severe mitral stenosis and the effect of Commissural Calcification (CC) on the outcomes.MethodsIn this single-center retrospective cohort study, 876 patients who underwent PBMV were categorized into three groups based on their Wilkins score (Group I: score ≤ 8, Group II: score 9–10, and Group III: score 11–12). Patients were evaluated before, early after PBMV and at 6- and 24-month follow-ups. Main clinical outcomes were defined as significant restenosis and or symptomatic significant MR (moderate to severe and severe MR) or candidate for mitral valve replacement (MVR). The outcomes were compared between patients with and without CC.ResultsA total of 876 patients with mean age 46.4 ± 12.3 years (81.0% females) were categorized based on Wilkins score. 333 (38.0%) were in Group I, 501 (57.2%) were in Group II, and 42 (4.8%) were in Group III. CC was present in 175 (20.0%) of the patients, among whom 95 (54.3%) had calcification of the anterolateral commissure, 64 (36.6%) had calcification of the posteromedial commissure, and in 16 (9.1%) patients both commissures were calcified. There was a significant difference in Wilkins score between patients with and without CC (P < 0.001). CC was associated with higher odds of significant symptomatic MR at early and mid-term follow up (OR: 1.69, 95%CI 1.19–2.41, P = 0.003; and OR: 3.90, 95%CI 2.61–5.83, P < 0.001, respectively), but not with restenosis (P = 0.128). Wilkins Groups II and III did not show higher odds of significant symptomatic MR compared to Group I at early (II: P = 0.784; III: P = 0.098) and mid-term follow up (II: P = 0.216; III: P = 0.227). Patients in Wilkins Group II had higher odds of restenosis compared to Group I (OR: 2.96,95%CI: 1.35–6.27, P = 0.007).ConclusionCommissural calcification (CC) is an independent predictor of the significant symptomatic MR (an important determinant of adverse outcome) following PBMV in the early and mid-term follow-up. Mitral valve restenosis occurs more in patients with higher Wilkins score compared to group I with score ≤ 8. Combined Wilkins score and CC should be considered for patient suitability for PBMV.

A case report on the use of combined spinal epidural technique in the anaesthetic care of a patient with a large ASD and severe pulmonary hypertension

A defect in the septum between the left and right atrium is known as atrial septal defect which is a congenital heart disease. The defect causes shunting of blood from left to right side of the heart, increasing the blood flow through the lungs. Small atrial septal defects may be found incidentally and never cause a major concern. Larger defects may damage the heart and also the lungs. The use of combined spinal and epidural technique in a patient with ASD can maintain hemodynamic stability, provide perioperative analgesia and also avoid the hemodynamic perturbations associated with general anaesthesia in a patient with severe pulmonary hypertension.

Effects of psilocin and psilocybin on human 5-HT4 serotonin receptors in atrial preparations of transgenic mice and humans

Several fungi belonging to the genus Psilocybe, also called “magic mushrooms”, contain the hallucinogenic drugs psilocybin and psilocin. They are chemically related to serotonin (5-HT). In addition to being abused as drugs, they are now also being discussed or used as a treatment option for depression. Here, we hypothesized that psilocybin and psilocin may act also on cardiac serotonin receptors and studied them in vitro in atrial preparations of our transgenic mouse model with cardiac myocytes-specific overexpression of the human 5-HT4 receptor (5-HT4-TG) as well as in human atrial preparations. Both psilocybin and psilocin enhanced the force of contraction in isolated left atrial preparations from 5-HT4-TG, increased the beating rate in isolated spontaneously beating right atrial preparations from 5-HT4-TG and augmented the force of contraction in the human atrial preparations. The inotropic and chronotropic effects of psilocybin and psilocin at 10 µM were smaller than that of 1 µM 5-HT on the left and right atria from 5-HT4-TG, respectively. Psilocybin and psilocin were inactive in WT. In the human atrial preparations, inhibition of the phosphodiesterase III by cilostamide was necessary to unmask the positive inotropic effects of psilocybin or psilocin. The effects of 10 µM psilocybin and psilocin were abrogated by 10 µM tropisetron or by 1 µM GR125487, a more selective 5-HT4 receptor antagonist. In summary, we demonstrated that psilocin and psilocybin act as agonists on cardiac 5-HT4 receptors.

First experience of treating patients with atrial fibrillation using thoracoscopic isolation with left atrial appendage excision in the North-Western State Medical University named after I.I. Mechnikov

The given article describes the first experience of a thoracoscopic isolation of pulmonary veins and left atrial appendage excision in the North-Western State Medical University named after I.I. Mechnikov. The clinical case features a woman with a long history of paroxysmal atrial fibrillation, severe left atrium dilation, failure in a pace control drug therapy and no effect of radiofrequency catheter isolation of pulmonary veins. Additionally, there outlined the advantages and the significance of employing the method of thoracoscopic ablation in patients with symptomatic paroxysmal and long-term persistent atrial fibrillation, — in case if antiarrythmic drugs and radiofrequency catheter ablation proved ineffective, as well as in patients with a long-term persistent atrial fibrillation along with a severe left atrium dilation.

Totally thoracoscopic atrial fibrillation surgery following massive small bowel resection due to superior mesenteric artery embolization: report of two cases

BackgroundThromboembolic occlusion of the superior mesenteric artery (SMA) is a grave complication in individuals diagnosed with atrial fibrillation (AF). This condition often necessitates extensive bowel resection, culminating in short bowel syndrome, which presents challenges for anticoagulant administration and/or antiarrhythmic therapy.Case presentationPresented here are findings of two patients, aged 78 and 72 years, respectively, who underwent comprehensive thoracoscopic AF surgery subsequent to extensive small bowel resection following SMA embolization. In each, onset of AF precipitated an embolic event, while the concurrent presence of short bowel syndrome complicated anticoagulation management. Total thoracoscopic AF surgery, comprised stapler-closure of the left atrial appendage (LAA) and bilateral epicardial clamp-isolation of the pulmonary veins, an operative modality aimed at addressing AF rhythm control and mitigating embolic events such as cerebral infarction, led to favorable outcomes in both cases. Additionally, computed tomography (CT) conducted one month post-surgery revealed the absence of residual tissue in the LAA, with the left atrium demonstrating a well-rounded, spherical shape. At the time of writing, the patients have remained asymptomatic following surgery regarding thromboembolic and arrhythmic manifestations for 29 and 10 months, respectively, notwithstanding the absence of anticoagulant or antiarrhythmic pharmacotherapy. Additionally, electrocardiographic surveillance has revealed persistent sinus rhythm.ConclusionsThe present findings underscore the feasibility and efficacy of a total thoracoscopic AF surgery procedure for patients presented with short bowel syndrome complicating SMA embolization, thus warranting consideration for its broader clinical application.

Catheter ablation for patients with anomalous pulmonary venous return and atrial fibrillation: A case report and literature review

Abstract Background Anomalous pulmonary venous return involves the partial or complete absence of a connection between the pulmonary veins and the left atrium. The pulmonary vein potential plays a vital role in atrial fibrillation, and catheter ablation to isolate the pulmonary vein is crucial for treating this condition. However, when anomalous pulmonary venous return is present, it makes ablation more challenging and increases the risk of atrial fibrillation recurrence after the procedure. Case summary A 49-year-old man was hospitalised because he had been experiencing occasional palpitations for 2 months. He had previously undergone surgery to repair an atrial septal defect when he was 11 years old, during which an issue with the right inferior pulmonary vein was identified but left unaddressed. Electrocardiography upon admission showed atrial fibrillation. Left atrial computed tomography angiography revealed that following atrial septal repair surgery, the right inferior pulmonary vein drained into the right atrium. The patient underwent transcatheter radiofrequency Mablation to electrically isolate the pulmonary vein with anomalous return. After 12 months of follow-up, there was no atrial fibrillation recurrence. Discussion When performing catheter ablation for anomalous pulmonary venous return and atrial fibrillation, it is essential to consider ablating the irregular pulmonary vein before surgery. This helps to reduce surgical complications and the likelihood of atrial fibrillation recurrence. This case report highlights the challenges encountered during ablation in patients with atrial fibrillation and anomalous pulmonary venous return. In addition, we have reviewed the literature to offer insights into the development of ablation strategies for similar patients.

The relationship between changes in peritoneal membrane solute transfer characteristics and cardiac remodeling in patients with peritoneal dialysis.

We aimed to determine the relationship between the dilatation of the heart chambers and the change in peritoneal membrane solute transfer characteristics (PMTC) in long-term peritoneal dialysis (PD) patients. This is a retrospective, single-center study including the follow-up of maintenance PD patients. According to the changes in PMTC from baseline to the last visit, patients were divided into three groups; stable (n = 11), increased (n = 41), and decreased transporters (n = 35). Left atrium (LA) and Right ventricle (RV) dilatation were more prominent in the PMTC-decreased group compared to PMTC-increased and stable groups (p < 0.001 and p = 0.07, respectively). The Cox regression analysis showed that only decreased PMTC was associated with LA dilatation (HR 2.89 [CI 95%1.54, 5.45] p < 0.01) and RV dilatation (HR 3.01 [CI 95%1.40, 6.21] p < 0.01). PD can be associated with unfavorable dynamic changes in cardiac structure and functions even at the subclinical level.

A novel function of claudin-5 in maintaining the structural integrity of the heart and its implications in cardiac pathology

This study aims to investigate the role of claudin-5 (Cldn5) in cardiac structural integrity. Proteomic analysis was performed to screen the protein profiles in enlarged left atrium from atrial fibrillation (AF) patients. Cldn5 shRNA adeno-associated virus (AAV) or siRNA was injected into the mouse left ventricle or added into HL1 cells respectively to knockdown Cldn5 in cardiomyocytes to observe whether the change of Cldn5 influences cardiac morphology and function, and affects those protein expressions stem from the proteomic analysis. Mitochondrial density and membrane potential were also measured by Mitotracker staining and JC-1 staining under the confocal microscope in HL1 cells. Cldn5 was reduced in cardiomyocytes from the left atrial appendage of AF patients compared to non-AF donors. Proteomic analysis showed 83 proteins were less abundant and 102 proteins were more abundant in AF patients. KEGG pathway analysis showed less abundant CACNA2D2, CACNB2, MYL2 and MAP6 were highly associated with dilated cardiomyopathy. Cldn5 shRNA AAV injection caused severe cardiac atrophy, dilation and myocardial dysfunction in mice. The decreases in mitochondrial numbers and mitochondrial membrane potentials in HL1 cells were observed after Cldn5 knockdown. We demonstrated for the first time the mechanism of Cldn5 downregulation-induced myocyte atrophy and myocardial dysfunction might be associated with the downregulation of CACNA2D2, CACNB2, MYL2 and MAP6, and mitochondrial dysfunction in cardiomyocytes.

MADR-Net: multi-level attention dilated residual neural network for segmentation of medical images

Medical image segmentation has made a significant contribution towards delivering affordable healthcare by facilitating the automatic identification of anatomical structures and other regions of interest. Although convolution neural networks have become prominent in the field of medical image segmentation, they suffer from certain limitations. In this study, we present a reliable framework for producing performant outcomes for the segmentation of pathological structures of 2D medical images. Our framework consists of a novel deep learning architecture, called deep multi-level attention dilated residual neural network (MADR-Net), designed to improve the performance of medical image segmentation. MADR-Net uses a U-Net encoder/decoder backbone in combination with multi-level residual blocks and atrous pyramid scene parsing pooling. To improve the segmentation results, channel-spatial attention blocks were added in the skip connection to capture both the global and local features and superseded the bottleneck layer with an ASPP block. Furthermore, we introduce a hybrid loss function that has an excellent convergence property and enhances the performance of the medical image segmentation task. We extensively validated the proposed MADR-Net on four typical yet challenging medical image segmentation tasks: (1) Left ventricle, left atrium, and myocardial wall segmentation from Echocardiogram images in the CAMUS dataset, (2) Skin cancer segmentation from dermoscopy images in ISIC 2017 dataset, (3) Electron microscopy in FIB-SEM dataset, and (4) Fluid attenuated inversion recovery abnormality from MR images in LGG segmentation dataset. The proposed algorithm yielded significant results when compared to state-of-the-art architectures such as U-Net, Residual U-Net, and Attention U-Net. The proposed MADR-Net consistently outperformed the classical U-Net by 5.43%, 3.43%, and 3.92% relative improvement in terms of dice coefficient, respectively, for electron microscopy, dermoscopy, and MRI. The experimental results demonstrate superior performance on single and multi-class datasets and that the proposed MADR-Net can be utilized as a baseline for the assessment of cross-dataset and segmentation tasks.