Topological charge-density-vector method of identifying filaments of scroll waves.

Scroll waves have been found in a variety of three-dimensional excitable media, including physical, chemical, and biological origins. Scroll waves in cardiac tissue are of particular significance as they underlie ventricular fibrillation that can cause sudden death. The behavior of a scroll wave is characterized by a line of phase singularity at its organizing center, known as a filament. A thorough investigation into the filament dynamics is the key to further exploration of the general theory of scroll waves in excitable media and the mechanisms of ventricular fibrillation. In this paper, we propose a method to identify filaments of scroll waves in excitable media. From the definition of the topological charge of filaments, we obtain the discrete expression of the topological charge-density vector, which is useful in calculating the topological charge vectors at each grid in the space directly. The set of starting points of these topological charge vectors represents a set of phase singularities, thereby forming a line of phase singularity, that is, a filament of a scroll wave.

Intracardiac echocardiography is a safe and effective alternative to transesophageal echocardiography for left atrial appendage thrombus evaluation at the time of atrial fibrillation ablation: The ICE-TEE study.

BACKGROUND: Intracardiac echocardiography (ICE) technology has been increasingly accepted as an integral part of atrial fibrillation (AF) ablation procedures. It is still unknown whether ICE can routinely replace transesophageal echocardiography (TEE) for routine thrombus screening in non-selective AF patients. OBJECTIVE: To assess whether ICE can routinely replace TEE in screening for left atrial (LA)/left atrial appendage (LAA) thrombus in general patients undergoing catheter ablation for AF. METHODS: A total of 2003 consecutive patients undergoing AF ablation were included. 1155 patients (ICE group) received intra-procedural ICE examination for LA/LAA thrombus screening, while 848 patients (TEE group) received pre-procedure TEE examination. The incidence of thrombus, peri-procedure complications, and hospital efficiency were assessed. RESULTS: The LA and LAA were adequately visualized in all patients. Five patients in the ICE group and 15 patients in the TEE group were found to have LAA thrombus. The incidence of major periprocedural thrombo-embolic events was comparable between two groups (0.2% vs. 0.1%, p = .76), none were due to undetected LA/LAA thrombus. Other major periprocedural complications occurred at similar rates in both groups, while post-procedure fever was less common in the ICE group (12.7% vs. 17.4%, p < .001). Procedure times and hospital length of stay were both shorter in the ICE group (142 min [87-197 min] vs. 150 min [95-205 min], and 3[2-4] day vs. 4[3-5] day, respectively, both p < .001). CONCLUSIONS: ICE can replace TEE for atrial thrombus screening in AF patients undergoing ablation without increased complications. An "ICE replacing TEE" workflow can also reduce the incidence of postoperative fever and improve hospital efficiency.

Selective Interventricular Septal Radiofrequency Ablation in Patients With Hypertrophic Obstructive Cardiomyopathy: Who Can Benefit?

Introduction: Septal mass reduction is beneficial for hypertrophic obstructive cardiomyopathy (HOCM) patients with severe left ventricular outflow (LVOT) gradient and symptoms, with surgical myectomy or alcohol septal ablation (ASA) currently recommended in selected patients. Radiofrequency (RF) ablation of hypertrophied septum has been published as a novel method to alleviate LVOT obstruction in small populations. This study aims to investigate factors influencing clinical outcomes of radiofrequency septum ablation. Methods and Results: In this study, 20 patients with HOCM who underwent endocardial ablation were included. Echocardiography and cardiac MRI (CMR) data was collected and analyzed pre- and (or) post- procedure. Nineteen patients underwent ablation successfully, while ablation was aborted in one patient with prior RBBB due to transient complete atrioventricular block (AVB). After 6 months of follow-up, NYHA heart functional class improved from III (2 - 3) to II (1 - 2) (p < 0.001), and resting LVOT gradient was significantly reduced (87.6 ± 29.5 mmHg vs. 48.1 ± 29.7, p < 0.001). LVOT gradient reduction was significantly higher in patients with limited basal septal hypertrophy (60.9 ± 8.3 vs. 27.9 ± 7.1, p = 0.01), shorter anterior mitral leaflet (56.1 ± 6.4 vs. 20.4 ± 5.0, p < 0.01), and normally positioned papillary muscle (36.9 ± 7.1 vs. 75.0 ± 6.3, p < 0.05). Conclusions: Endocardial septal ablation appears to be a safe and effective procedure for alleviating LVOT gradient in patients with HOCM, especially in those with limited basal septal hypertrophy, shorter anterior mitral leaflet, and normal positioned papillary muscle.

Topological charge-density method of identifying phase singularities in cardiac fibrillation.

Spiral waves represent the key motifs of typical self-sustained dynamical patterns in excitable systems such as cardiac tissue. The motion of phase singularities (PSs) that lies at the center of spiral waves captures many qualitative and, in some cases, quantitative features of their complex dynamics. Recent clinical studies suggested that ablating the tissue at PS locations may cure atrial fibrillation. Here, we propose a different method to determine the location of PSs. Starting from the definition of the topological charge of spiral waves, we obtain the expression of the topological charge density in a discrete case. With this expression, we can calculate the topological charge at each grid in the space directly, so as to accurately identify the position of PSs.

Puerarin Decreases Collagen Secretion in AngII-Induced Atrial Fibroblasts Through Inhibiting Autophagy Via the JNK-Akt-mTOR Signaling Pathway.

Puerarin is used to treat cardiovascular diseases due to its anti-inflammatory and antifibrotic effects. However, its mechanism of action in atrial fibroblasts is unknown. In this study, we investigated the autophagy pathway and molecular changes in angiotensin II (AngII)-stimulated atrial fibroblasts in response to puerarin treatment. Atrial fibroblasts were cultured and then subjected to stimulation with AngII and puerarin or other chemical drugs (3-MA, CQ, and SP600125). Quantitative real-time polymerase chain reaction and Western blot experiments were used to quantify the expression levels of mRNA and protein. mCherry-GFP-LC3 adenovirus was applied to reflect the autophagic flux. The results showed aggravating levels of autophagy and collagen deposit in the presence of AngII. Puerarin inhibited autophagy and decreased collagen secretion in a dose-dependent manner in atrial fibroblasts. Furthermore, phosphorylation of JNK was down-regulated in response to puerarin, whereas phosphorylation of Akt and mammalian target of rapamycin (mTOR) was upregulated. Interestingly, reduced autophagy and collagen secretion were observed when the JNK signaling pathway was blocked using SP600125. We also observed upregulation of Akt and mTOR phosphorylation in the presence of SP600125. These results suggest that puerarin exerts its antifibrotic effect in atrial fibroblasts partly through the inhibition of autophagy. Furthermore, the mechanism of action of puerarin in fibroblast autophagy seems to be mediated partly through JNK-Akt-mTOR signaling.