Impact of catheter-tissue contact force on lesion size during right ventricular outflow tract ablation in a swine model.

BACKGROUND: The catheter-tissue contact force (CF) is one of the significant determinants of lesion size and thus has a considerable impact on the effectiveness of ablation procedures. This study aimed to evaluate the impact of CF on the lesion size during right ventricular outflow tract (RVOT) ablation in a swine model. METHODS: Twelve Guangxi Bama miniature male pigs weighing 40 to 50 kg were studied. After general anesthesia, a ThermoCool SmartTouch contact-sensing ablation catheter was introduced to the RVOT via the femoral vein under the guidance of the CARTO 3 system. The local ventricular voltage amplitude and impedance were measured using different CF levels. We randomly divided the animals into the following four groups according to the different CF levels: group A (3-9 g); group B (10-19 g); group C (20-29 g); and group D (30-39 g). Radiofrequency ablations were performed at three points in the free wall and septum of the RVOT in power control mode at 30 W for 30 s while maintaining the saline irrigation rate at 17 mL/min. At the end of the procedures, the maximum depth, surface diameter, and lesion volume were measured and recorded. A linear regression analysis was performed to determine the relationship between continuous variables. RESULTS: A total of 72 ablation lesions were created in the RVOT of the 12 Bama pigs. The maximum depth, surface diameter, and volume of the lesions measured were well correlated with the CF (free wall: ß = 0.105, ß = 0.162, ß = 3.355, respectively, P < 0.001; septum: ß = 0.093, ß = 0.150, ß = 3.712, respectively, P < 0.001). The regional ventricular bipolar voltage amplitude, unipolar voltage amplitude, and impedance were weakly positively associated with the CF (ß = 0.065, ß = 0.125, and ß = 1.054, respectively, P < 0.001). There was a significant difference in the incidence of steam pops among groups A, B, C, and D (free wall: F = 7.3, P = 0.032; septum: F = 10.5, P = 0.009); and steam pops occurred only when the CF exceeded 20 g. Trans-mural lesions were observed when the CF exceeded 10 g in the free wall, while the lesions in the septum were non-trans-mural even though the CF reached 30 g. CONCLUSIONS: CF seems to be a leading predictive factor for the size of formed lesions in RVOT ablation. Maintaining the CF value between 3 and 10 g may be reasonable and effective for creating the necessary lesion size and reducing the risk of complications, such as steam pops and perforations.

Comparison of Empiric Isolation and Conventional Isolation of Superior Vena Cava in Addition to Pulmonary Vein Isolation on the Outcome of Paroxysmal Atrial Fibrillation Ablation.

Radiofrequency catheter ablation (RFCA) in the treatment of AF is currently based on pulmonary vein isolation (PVI). Some studies have investigated the efficacy of empiric SVC isolation (SVCI) in addition to conventional PVI in order to improve success rates and reduce recurrence rates. However, the results of the studies have given conflicting data.We performed a meta-analysis to evaluate the efficacy and safety of the empiric SVCI compared with conventional SVCI for paroxysmal atrial fibrillation (PAF) ablation.We searched MEDLINE, EMBASE, the Web of Science, and the Cochrane Database from the period January 1986 to August 2016 and identified qualified studies. The primary clinical outcome was the recurrence rate of atrial tachyarrhythmias, and the secondary clinical outcomes were procedure time, fluoroscopy time, and complications.We identified 3 randomized controlled trials (RCTs) and one nonrandomized, observational study (nROS) involving 245 patients with empiric SVCI and 269 patients with conventional SVCI. The empiric SVCI group had a lower recurrence rate of atrial tachyarrhythmia after a single procedure compared with the conventional SVCI group (16.7% versus 29.4%, OR: 0.48, 95%CI: 0.31 to 0.74, P = 0.0009). There was no significant difference in fluoroscopic time (P = 0.22), procedure time (P = 0.32), or clinical complications (P = 0.33) between the two groups.Empiric SVCI is more effective than conventional SVCI in terms of the long-term outcomes of PAF patients after a single PVI procedure, with the same fluoroscopic time, procedure time, and clinical complications.

Ventricular Tachycardia Originating from Moderator Band: New Perspective on Catheter Ablation.

A 59-year-old woman was referred to the institution with burdens of idiopathic ventricular tachycardia (IVT). Electroanatomic mapping revealed a complex fractionated, high frequency potential with long duration preceding the QRS onset of the IVT. The real end point of ablation was the disappearance of the conduction block of Purkinje potential during the sinus rhythm besides the disappearance of the inducible tachycardia. Location of distal catheter was at the moderator band (MB) by transthoracic echocardiography (TTE). Only irrigated radiofrequency current was delivered at both insertions of the MB which can completely eliminate the IVT.

Anaesthesia modalities during laser photocoagulation for retinopathy of prematurity: a retrospective, longitudinal study.

OBJECTIVES: Laser photocoagulation surgery is a routine treatment for threshold retinopathy of prematurity (ROP). However, little is known about which anaesthesia protocols provide efficient pain control while minimising exposure risk to vulnerable infants. In this study, therefore, we assessed the efficacy and tolerability of multiple anaesthesia techniques used on premature infants during laser therapy. DESIGN AND MAIN OUTCOME MEASURES: Anaesthesia modalities consisted of topical eye drops anaesthesia, general anaesthesia and intravenous fentanyl sedation with mechanical ventilation. Laser treatment efficacy and detailed operative information were retrospectively and consecutively analysed. Cardiorespiratory stability was assessed and compared. The Neonatal Pain Agitation and Sedation Scale (N-PASS) was used to evaluate tolerability in infants that underwent intravenous fentanyl sedation. RESULTS: 97 cases of prematurity were included in this study. In 94/97 (96.9%) cases, vascular proliferation regressed. In the topical anaesthesia groups, the ophthalmologist needed 12-16 min more to complete the treatment. During the 3 postoperative days, topical anaesthesia demonstrated the greatest instability; 4/31 (12.90%) infants in this group suffered from life threatening events requiring resuscitation. The only instability observed in general anaesthesia and fentanyl sedation was attributed to difficulty in extubating within 24 hours after surgery. During laser therapy, the N-PASS score increased to 1.8 in the fentanyl sedation group. CONCLUSIONS: Topical anaesthesia was associated with more cardiorespiratory instability during ROP laser treatment. While general anaesthesia and fentanyl sedation had similar postoperative cardiorespiratory results, the latter demonstrated acceptable pain stress control. However, the difficulty of weaning off mechanical ventilation in some cases after surgery needs to be addressed in future studies.

Systemic changes and adverse effects induced by retinopathy of prematurity screening.

AIM: To estimate the potential systemic events during and after retinopathy of prematurity (ROP) screening. METHODS: A prospective and descriptive designed study was conducted to detect the physiologic and pathological changes 24h before, during, and 72h after ROP screening. Control blood pressure (BP), saturation, pulse rate, and body temperature were routinely taken at various time internals before and after screening. Adverse effects pertain to cardiovascular system, respiratory system, gastric system, urinary system and nervous system were retrospect 0-72h after ROP screening at a 24-hour interval. RESULTS: Totally 1254 prematurity babies receiving ROP screening during Jan. 1(st) 2013 to Dec. 31(th) 2013 were enrolled in our survey. Compared to control vital sign data taken before the examination, there was a fluctuation in the diastolic BP with the increased 3.03 mm Hg (P=0.04) after 3 doses of mydriatic drops. Immediately after the examination, there was a further 12.64 mm Hg (P<0.01) increase in systolic BP and a 7.24 mm Hg (P<0.01) in diastolic BP. The mean pulse rate during examination was 22.4 bpm (P<0.01) higher than the 133.3±9.0 bpm control level. The oxygen saturation shared an average drop of 5% (P<0.01) during screening. In prematurity with postconceptional age less than 31wk, the incidence of apnea (23.5%), necrotizing enterocolitis (NEC) (8.7%), gastric residual (25.4%) and upper digestive tract hemorrhage (6.4%) also demonstrated a significant rise (P<0.01). CONCLUSION: In our study sample, ROP screening was associated with NEC, gastric residual and upper digestive tract hemorrhage. These gastrointestinal side effects, along with breath activity pattern change and vital signs indicators fluctuation, may be results of additional stress responses.

Identification of Iron Homeostasis Genes Dysregulation Potentially Involved in Retinopathy of Prematurity Pathogenicity by Microarray Analysis.

Retinopathy of prematurity (ROP) is a serious disease of preterm neonates and there are limited systematic studies of the molecular mechanisms underlying ROP. Therefore, here we performed global gene expression profiling in human fetal retinal microvascular endothelial cells (RMECs) under hypoxic conditions in vitro. Aborted fetuses were enrolled and primary RMECs were isolated from eyeballs. Cultivated cells were treated with CoCl2 to induce hypoxia. The dual-color microarray approach was adopted to compare gene expression profiling between treated RMECs and the paired untreated control. The one-class algorithm in significance analysis of microarray (SAM) software was used to screen the differentially expressed genes (DEGs) and quantitative RT-PCR (qRT-PCR) was conducted to validate the results. Gene Ontology was employed for functional enrichment analysis. There were 326 DEGs between the hypoxia-induced group and untreated group. Of these genes, 198 were upregulated in hypoxic RMECs, while the other 128 hits were downregulated. In particular, genes in the iron ion homeostasis pathway were highly enriched under hypoxic conditions. Our study indicates that dysregulation of genes involved in iron homeostasis mediating oxidative damage may be responsible for the mechanisms underlying ROP. The "oxygen plus iron" hypothesis may improve our understanding of ROP pathogenesis.

Characterization of Two GAS1 Genes and Their Effects on Expression and Secretion of Heterologous Protein Xylanase B in Kluyveromyces lactis.

ß-1,3-glucanosyltransferases play essential roles in cell wall biosynthesis in yeast. Kluyveromyces lactis has six putative ß-1,3-glucanosyltransferase genes. KlGAS1-1 and KlGAS1-2 are homologs of Saccharomyces cerevisiae gene GAS1. RT-qPCR indicated the transcription level of KlGAS1-1 was significantly reduced while heterologous protein (thermostable xylanase B) secretion was enhanced during medium optimization. To evaluate if these two events were related, and to improve xylanase B secretion in K. lactis, we constructed KlGAS1-1 and KlGAS1-2 single deletion strains and double deletion strain, respectively. KlGAS1-1 gene deletion resulted in the highest xylanase B activity among the three mutants. Only the double deletion strain showed morphology similar to that of the GAS1 deletion mutant in S. cerevisiae. The two single deletion strains differed in terms of cell wall thickness and xylanase B secretion. Transcription levels of ß-1,3-glucanosyltransferase genes and genes related to protein secretion and transport were assayed. The ß-1,3-glucanosyltransferase genes displayed transcription complementation in the cell wall synthesis process. KlGAS1-1 and KlGAS1-2 affected transcription levels of secretion- and transport-related genes. Differences in protein secretion ratio among the three deletion strains were associated with changes of transcription levels of secretion- and transport-related genes. Our findings indicate that KlGAS1-1 deletion is an effective tool for enhancing industrial-scale heterologous protein secretion in K. lactis.

Clinical assessment and polysomnographic study of sleep apnea in a Chinese population of snorers.

BACKGROUND AND OBJECTIVES: While an increasing number of people who snore are seeking medical consultations, the clinical characteristics of snorers are rarely reported. The aim of this study is to characterize the clinical and polysomnographic features in a population of snorers. METHODS: A total of 490 subjects were examined retrospectively. The clinical history, Epworth Sleepiness Scale (ESS) scores, physical examination, and full-night polysomnography (PSG) data were obtained for all the subjects. The correlations between the neck circumference, waist circumference, ESS scores, body mass index (BMI), and apnea-hypopnea index (AHI) of obstructive sleep apnea (OSA) patients were explored. The gender and age differences in OSA patients were analyzed. RESULTS: OSA was diagnosed in 84.7% of the sample, with 21.2% of the patients having a mild form, 15.4% having a moderate form, and 63.4% having a severe form of OSA. The ESS scores, neck circumference, waist circumference, and BMI were positively correlated with AHI in OSA patients. The ESS scores and BMI were negatively correlated with nadir oxygen saturation (SaO2). A greater number of men than women exhibited moderate to severe forms of the disease. OSA affects the work of males more commonly compared with females. Nocturia was a more common complaint in elderly OSA patients. Heart diseases coexisted more frequently with OSA in elderly patients. CONCLUSIONS: In a population of snorers, OSA is the most common condition identified. The ESS scores and BMI were well correlated with the severity of the disease. Men had a more severe form of OSA than women. Nocturia frequently occurred in elderly OSA patients, as did the coexistence of heart disease.

[Effect of vascular endothelial growth factor small interfering RNA (siRNA) on retinal microvascular endothelial cells under hypoxia condition in vitro].

OBJECTIVE: To explore VEGF siRNA's effect on the immature fetal retinal microvascular endothelial cells in vitro. METHOD: The fresh retinal micrangium was primarily cultured to obtain microvascular endothelial cells. CoCl2 was used to simulate oxygen-deficient conditions. siRNA directed against human VEGF was designed and chemically synthesized. There were 3 groups in our experiment: VEGF siRNA group, hypoxia control group, and negative siRNA control group. The fetal retinal micrangium vascular endothelial cells were transfected by using liposome. The expression levels of VEGF mRNA and protein were evaluated by RT-PCR and Western blotting 24, 48, 72 h after transfection, cell proliferation was evaluated by MTT method. RESULT: The expression levels of VEGF mRNA decreased by 21.05%, 79.67%, and 90.48% 24 h, 48 h, and 72 h after transfection as compared to those in hypoxia control group, the expression level of VEGF protein had decreased by 14.58%, 66.97%, and 81.61% as compared to those in hypoxia control group. The siRNA could decrease cell proliferation under hypoxia too, the multiplication rate after 12, 24, 48, and 72 h decreased by 15.0%, 42.9%, 78.3% and 65.9%. CONCLUSION: VEGF siRNA could down-regulate the expression of VEGF in immature fetal retinal microvascular endothelial cells and suppressed cell proliferation. Application of siRNA to inhibit expression of VEGF may be a hopeful way to prevent and cure ROP.