Simplified stepwise anatomical ablation strategy for mitral isthmus: efficacy, efficiency, safety, and outcome.

AIMS: Bidirectional and durable block of mitral isthmus (MI) is essential for catheter ablation of persistent atrial fibrillation (PeAF) and perimitral flutter (PMF), but it remains a challenge. The aim of this study was to create a simple anatomical ablation strategy with minimal fluoroscopy that would yield a high success rate for MI block. METHODS AND RESULTS: Patients with PeAF or PMF were included. Mitral isthmus was ablated in a stepwise strategy. In Step 1, endocardial MI linear ablation was performed; in Step 2, ablation was targeted to the posterolateral portion of the left atrium along the MI line; in Step 3, epicardial ablation within the coronary sinus (CS) was performed across the MI line to the ostium of the vein of Marshall (VOM) or performed within the VOM if available; in Step 4, the catheter was rotated and ablated in the CS to isolate the CS; and in Step 5, the early activation site with complex component potential above the MI line during distal CS pacing was considered as the ablation target. All patients were followed up. A total of 178 (17 patients with mechanical prosthetic mitral valve) were included. One hundred and sixty-six patients achieved a confirmed MI bidirectional conduction block (93%). One patient had cardiac tamponade. Four patients showed re-conduction across the MI line during a repeated ablation. In the latest follow-up [12 (7, 16) months], 161 of 178 (90%) patients maintained their sinus rhythm. CONCLUSION: A simple stepwise anatomical ablation strategy for MI shows a high success rate with low fluoroscopy exposure.

Long chain noncoding RNA-ROR promotes hypoxic injury of cardiomyocytes by targeting the miR-145/HAX-1 axis.

Background: Long non-coding RNAs (lncRNAs) are a class of non-protein coding RNAs greater than 200 nucleotides (nt) in length which have been shown to be significantly highly expressed in the heart tissue of mice undergoing thoracic aortic arch constriction (TAC). Micro RNAs (miRNAs) are a class of non-protein-coding RNAs. Many miRNAs have been reported to play a key role in the progression of myocardial hypertrophy. In this study, we aimed to investigate whether lncRNA reprogramming regulators (ROR) promotes hypoxic injury in cardiomyocytes by targeting and regulating the miR-145/HS1-associated protein X-1 (HAX-1) axis. Methods: A mouse model of myocardial hypertrophy was established by conventional TAC method, and the cardiomyocytes were isolated. We transfected pcDNA3.0-ROR vector, pcDNA3.0-HAX-1 vector plasmid, and miR-145 simulant into cardiomyocytes with Lipofectamine 2000. Luciferase reporter gene was used to analyze the targeting relationship between genes. Results: The expression of ROR in hypertrophic myocardium was significantly increased after phenylephrine (PE) intervention. After transfection with si-ROR, the ROR expression in hypertrophic cardiomyocytes treated with PE decreased significantly. Levels of lactate dehydrogenase (LDH), malondialdehyde (MDA), creatine kinase (CK) decreased and superoxide dismutase (SOD) increased. The expression of miR-145 in cardiomyocytes was significantly down-regulated after PE treatment. In hypertrophic cardiomyocytes, after up-regulating the expression of miR-145, the relative messenger ribonucleic acid (mRNA) and protein expressions of atrial natriuretic peptide (ANP) and B-type natriuretic peptide (BNP) induced by PE decreased. Compared with the miR-NC group, wild type (WT)-ROR activity in the miR-145 group was significantly inhibited (P<0.05), and mutant (MUT)-ROR activity had no significant change (P>0.05). When cardiomyocytes were transfected with HAX-1 3'URT WT vector along with miR-145 simulant, miR-145 inhibitor, and their respective controls. Compared with the control groups, the luciferase activity of cells transfected with simulant was significantly decreased (P<0.05), and increased in inhibitor group (P<0.05). Transfection of HAX-1 3'URT mutant vector did not show this phenomenon. ROR was negatively correlated with miR-145 expression and positively correlated with HAX-1 mRNA. Conclusions: The lncRNA ROR can promote the expression of HAX-1 by competitive binding with miR-145, so as to promote the pathophysiological process of myocardial hypertrophy.

Everolimus (RAD001) inhibits the proliferation of rat vascular smooth muscle cells by up-regulating the activity of the p27/kip1 gene promoter.

OBJECTIVE: We investigated whether the inhibitory effect of the immunosuppressant everolimus (RAD001) on vascular smooth muscle cell (VSMC) proliferation is mediated by p27/kip1 gene promoter activity. METHODS: In this experimental study, cultured rat VSMCs were transiently transfected with a recombinant plasmid (pXp27) containing p27/kip1 gene promoter sequence and a chloramphenicol acetyltransferase (CAT) reporter gene. After stimulation with the mitogen platelet-derived growth factor (PDGF-BB, 10 ng/mL) in the presence or absence of RAD001 (10 nM), the promoter activity, mRNA expression, and protein expression of p27/kip1 were examined by CAT assay, RT-PCR, and immunoblotting, respectively. Cell cycle-related changes were detected by flow cytometry. DNA synthesis was determined using 3H-TdR incorporation. RESULTS: Compared with the non-stimulation group, PDGF-BB stimulation induced a significant proliferative response in the VSMCs as indicated by decreased p27/kip1 gene promoter activity, decreased p27/kip1 mRNA and protein expression, increased S-phase and G2/M-phase cells, and increased DNA synthesis. RAD001 intervention increased p27/kip1 gene promoter activity 3.5-fold, promoted p27/kip1 mRNA and protein expression, increased G0-phase cells, reduced DNA synthesis, and, overall, inhibited PDGF-BB-stimulated cell proliferation. CONCLUSION: RAD001 inhibits PDGF-BB-stimulated proliferation of cultured VSMCs by upregulating p27/kip1 gene promoter activity and increasing p27/kip1 mRNA and protein expression.