OBJECTIVETo study regulation of Ca(2+)-activated K(+) channels (KCa) of mesenteric artery smooth muscle cell (SMC) from 21 old patients with essential hypertension (EH) by endothelin-1 (ET-1) and prostagl E(1) (PGE(1)).

METHODSMesenteric artery branch from EH was digested by enzyme. Patch clamp technique was used to pull cell-attached and inside-out patches on mesenteric artery SMC from EH and the normotensive patients respectively. The signal channel open probability (Po), open dwell-time (To) and close dwell-time (Tc), open channel number per patch were recorded. After adding Ca(2+) (10(-8) approximately 10(-6) mol/L), ET-1(2 approximately 8 x 10(9) mol/L) and PGE(1) (10, 20, 40, 100, 200, 400 nmol/L) to cytoplasm respectively. The parameters above were observed again.

RESULTSCompared to that of normotensive patients, the activities of KCa channels of patients with EH was higher. After adding Ca(2+) to cytoplasm,the Po of KCa channels in normotensive patients increased significantly. But it was few changes in EH group. KCa channels has dual reaction to ET-1 in normotensive patients. We have found no statistics difference when ET-1 present on KCa channels of EH cases. Whereas PGE(1) can affect KCa channels current and channels kinetic significantly in side-out patches. The Po of KCa channels increased. The To protracted and the Tc curtailed in EH.

CONCLUSIONSThe activities of KCa channels of patients with EH increased significantly. but the sensitive to Ca(2+) decreased. ET-1 were few effect to KCa channels. The PGE(1) can activated KCa channels of patients with EH.

Aged ; Alprostadil ; pharmacology ; Cells, Cultured ; Endothelin-1 ; pharmacology ; Female ; Humans ; Hypertension ; metabolism ; physiopathology ; In Vitro Techniques ; Male ; Mesenteric Arteries ; cytology ; Middle Aged ; Muscle, Smooth ; metabolism ; physiopathology ; Patch-Clamp Techniques ; Potassium Channels, Calcium-Activated ; drug effects ; metabolism

Catheter Ablation ; Child ; Heart Septal Defects, Atrial ; surgery ; Humans ; Imaging, Three-Dimensional ; Male ; Tachycardia, Supraventricular ; surgery ; Tomography, X-Ray Computed

OBJECTIVETo prepare a stable water-based magnetic fluid.

METHODSA water-based magnetic fluid was prepared by addition of polyvinylpyrrolidone (PVP) as the coating agent for the magnetic particles. After preparation of Fe3O4 by co-precipitation method, PVP was added for its coating, followed by ultrasonic agitation and purification.

RESULTSThe magnetic nanoparticles of homogeneously small size and water-based magnetic fluid were obtained, which had good dispersion in water with strong magnetism.

CONCLUSIONPVP can be used as a surfactant to stabilize the magnetic fluid.

Ferrous Compounds ; chemistry ; Magnetics ; Materials Testing ; Nanoparticles ; chemistry ; Povidone ; chemistry ; Surface Properties ; Surface-Active Agents ; chemical synthesis ; chemistry

OBJECTIVETo investigate the influence of persistent rapid atrial pacing on the levels of connexin 43 (Cx43) and type III collagen in pulmonary vein and atrium in a canine model.

METHODSSixteen mongrel dogs were divided into rapid atrial pacing (RAP) group (n = 8) and normal control group (n = 8) randomly. In the RAP group, atrial pacing was performed with a rate of 400 bpm for 10 weeks to establish atrial fibrillation model. The tissues of left superior pulmonary vein (LSPV), left atrial free wall (LAFW) and right atrial appendage (RAA) were collected from each dogs. The levels of Cx43 and type III collagen were measured in each tissue.

RESULTSTen weeks later, persistent atrial fibrillation was induced in all dogs in RAP group. The level of Cx43 in RAP group was higher than that in normal control group (LSPV: 3370.91 +/- 275.11 vs 1405.82 +/- 90.38, P < 0.05; LAFW: 2448.68 +/- 272.10 vs 1467.12 +/- 147.93, P < 0.05, RAA: 2331.96 +/- 199.61 vs 1288.27 +/- 216.22, P < 0.05). The level of Cx43 in LSPV was higher than that in LAFW and RAA in RAP group, whereas the difference between LAFW and RAA was not significant in RAP group. The quantities of type III collagen in RAP group were higher than those in normal control group (LSPV: 3301.97 +/- 309.70 vs 1404.56 +/- 178.02, P < 0.05; LAFW: 2477.86 +/- 190.43 vs 1479.20 +/- 187.17, P < 0.05; RAA: 2045.92 +/- 139.43 vs 1417.07 +/- 139.43, P < 0.05). The quantities of type III collagen in LSPV was higher than those in LAFW and RAA in RAP group.

CONCLUSIONSPersistent rapid atrial pacing could increase the levels of Cx43 and type III collagen in pulmonary vein and atrium in a canine model of atrial fibrillation. The levels of Cx43 and type III collagen in pulmonary vein were higher than those in atrium. This findings indicated that pulmonary vein may be a crucial regions in maintaining atrial fibrillation.

Animals ; Atrial Fibrillation ; metabolism ; physiopathology ; Cardiac Pacing, Artificial ; methods ; Collagen Type III ; blood ; Connexin 43 ; blood ; Disease Models, Animal ; Dogs ; Female ; Male ; Pulmonary Veins ; metabolism ; physiopathology

Animals ; Asia ; epidemiology ; History, 20th Century ; Humans ; Influenza A Virus, H2N2 Subtype ; chemistry ; genetics ; isolation & purification ; Influenza, Human ; epidemiology ; history ; virology ; Mutation

Background Recurrent atrial tachyarrhythmia (ATa) after circumferential pulmonary vein ablation (CPVA) includes atrial tachycardia (AT) and atrial fribrillation (AF). However, whether there are some differences in clinical course and mechanisms between the recurrent AT and the recurrent AF remained unclear. This study was conducted to investigate the incidence, mechanism, clinical course of the recurrent AT and AF in patients under CPVA.Methods One hundred and thirty consecutive patients (M/F=95/35) with highly symptomatic and multiple antiarrhythmic drugs (AADs) refractory paroxysmal (n=91) or persistent (n=39) AF were included. The ablation protocol consisted solely of two continuous circular lesions around the ipsilateral pulmonary veins (PV) guided by CARTO system. The endpoint of CPVA is PV isolation. For patients with recurrent ATa within 2 months after the initial procedure, cardioversion with direct current was attempted if the ATa lasted for more than 24 hours. A repeat ablation procedure was performed only for patients with AADs refractory recurrent ATa and at least followed up for 2 months after the initial procedure.Results Within 2 months after the initial procedure, 52 patients (40.0%) had experienced episodes of symptomatic recurrent ATa. Among them, 23 patients (44.2%) with recurred AT alone (AT group), 14 patients (26.9%) with recurred AF alone (AF group), and 15 patients (28.8%) with recurred AT and AF (AT plus AF group). The delayed cure rate (65.2%) in AT group was significant higher than that in AF group (21.4%, P<0.05) and AF plus AT group (26.7%, P<0.05). A repeat ablation was performed in 21 patients, including 6 patients with recurrent AT alone, 8 patients with recurrent AF alone, and 7 patients with recurrent AF plus AT. The mean number of PV gaps was 1.2±0.4 in AT group, which was significantly lower than that in AF group (2.6±0.7, P<0.05) and AF plus AT group (2.0±0.6, P<0.05). Delayed cure rate and number of PV gaps between AF group and AF plus AT group were comparable (P>0.05).Conclusions Present study indicates that recurrent AT and AF after CPVA have the different clinical course and different electrophysiological findings during repeat procedure as follows: ⑴After CPVA, spontaneous resolution of recurrent ATa was mainly found in patients with recurrent AT alone (about two thirds patients). ⑵The type of recurrent ATa after CPVA is associated with the number of PV gaps.

AIMTo study the expressions of scavenger receptor class B type I(SR-BI) and peroxisome proliferator-activated receptor gamma (PPARgamma) in atherosclerotic mini swine and provide a new mechanism for investigating the pathogenesis of atherosclerosis.

METHODSChinese mini swine were fed by a normal control diet or a high fat/high cholesterol diet for 12 months after common carotid artery injury induced by balloon denudation. Plasma total cholesterol(TC), high-density lipoprotein cholesterol (HDL-C) and triglycerides (TG) were determined by commercially enzymatic methods every two months. The sections, which were taken from liver and abdominal aorta, were stained with hematoxylin eosin. The expressions of SR-BI and PPARgamma mRNA and protein in liver and aorta tissue were detected by reverse transcriptase-polymerase chain reaction (RT-PCR), Western blot and immunohistochemistry respectively.

RESULTSAt the end of 12 months, plasma TC, HDL-C and TG in HFHC mini swine were increased. There were fatty liver and atherosclerotic plaque in mini swine live and aorta respectively. The expression of SR-BI was upregulated in HFHC mini swine liver and aorta tissue.

CONCLUSIONHFHC may induce atherosclerosis and the expression of SR-BI and PPARgamma. Upregulating SR-BI expression may inhibit atherosclerosis. Increasing SR-BI expression in liver and aorta may accelerate SR-BI-mediated reverse cholesterol transport and develop a new anti-atherogenic strategy.

Animals ; Arteriosclerosis ; pathology ; Atherosclerosis ; metabolism ; PPAR gamma ; metabolism ; Receptors, Scavenger ; metabolism ; Swine

BACKGROUNDExtensive atrial fibrillation (AF) ablation is associated with an increased success rate of catheter ablation in chronic AF patients and an increased rate of atrial tachycardia (AT) during the procedure. The mechanism of these ATs varies in previous studies. Our study aimed to report the mechanism of organized AT occurring during the stepwise ablation procedure of chronic AF.

METHODSA prospective cohort of 86 consecutive patients who underwent an ablation procedure for chronic atrial fibrillation (CAF) was investigated. The stepwise procedure was performed in the following order: circumferential pulmonary vein ablation, complex fractionated atrial electrograms ablation, mapping and ablation of AT. The endpoint was noninducibility of AF/AT after sinus rhythm (SR) was restored or the procedure time was beyond 6 hours.

RESULTSSixty-nine (80%) of patients converted to SR via AT. A total of 179 sustained ATs were observed in 69 patients during the procedure. There were 81% (n = 145) macroreentrant ATs which included 65 perimitral circuits, 48 peritricuspid tachycardia and 32 roof dependent circuits, 12% (n = 21) localized reentrant and 7% (n = 13) focal ATs. Thirty (15%) patients experienced significant left atrium (LA) and LA appendage (LAA) conduction delay or dissociation in the procedure or during the follow-up period.

CONCLUSIONSMost CAF patients converted to SR via ablation of organized AT occurring during the stepwise procedure. The mechanism of most of these ATs was macro-reentry.

Aged ; Atrial Fibrillation ; surgery ; Catheter Ablation ; methods ; Electrophysiology ; Female ; Humans ; Male ; Middle Aged ; Prospective Studies ; Tachycardia, Ectopic Atrial ; surgery ; Treatment Outcome

BACKGROUNDIt is unclear whether a history of paroxysmal atrial fibrillation (PAF) would impact the effect of catheter ablation on persistent atrial fibrillation (AF). This study aimed to compare the effect of catheter ablation on persistent AF with and without a history of PAF.

METHODSOne hundred and eighty-three patients underwent catheter ablation of persistent AF lasting for > 1 month and were reviewed. Patients were divided into two groups according to whether they had a history of PAF or not. Group I consisted of persistent AF patients with a history of PAF, and group II consisted of persistent AF patients without such a history. All patients received catheter ablation focused on pulmonary vein isolation and were observed for arrhythmia recurrences, which were defined as documented episodes of AF or atrial tachycardia after a blanking period of 3 months.

RESULTSOne hundred and three patients (60.9%) in group I and sixty-six patients (39.1%) in group II were successfully followed and included in analysis. There were no significant differences in clinical and echocardiographic characteristics between both groups except for a younger age and more male patients in group II. After (15.5 ± 10.7) months of follow-up, 59 (57.3%) patients in group I and 49 (74.2%) patients in group II maintained sinus rhythm free of anti-arrhythmia drugs (P = 0.025). Multivariate analyses found left atrial anteroposterior diameter (P = 0.006) and persistent AF with a history of PAF (OR 1.792, 95%CI 1.019 - 3.152; P = 0.043) as the only independent statistical predictors of arrhythmia recurrences.

CONCLUSIONThe arrhythmia recurrence rate of catheter ablation based on pulmonary vein isolation in persistent AF with a history of PAF was higher than those without a history of PAF.

Adult ; Aged ; Atrial Fibrillation ; surgery ; Catheter Ablation ; Female ; Humans ; Male ; Middle Aged ; Proportional Hazards Models ; Pulmonary Veins ; surgery ; Recurrence

The present report demonstrates two cases of transient inferior ST-segment elevation accompanied by profound hypotension and bradycardia immediately after transseptal puncture for catheter ablation of atrial fibrillation. This rare complication of transseptal puncture was resolved quickly within several minutes. The most likely mechanism of this phenomenon is coronary vasospasm, although coronary embolism can not be ruled out completely. This complication is characterized as follows: (1) The right coronary artery might be the most likely involved vessel and therefore myocardial ischemia usually occurs in the inferior wall of left ventricular; (2) Reflex hypotension and bradycardia by the Bezold-Jarisch reflex secondary to inferior ischemia often occur at the same time. Though it appears to be a transient and completely reversible phenomenon, there are still potential life-threatening risks because of myocardial ischemia and profound haemodynamic instability. Clinical cardiologists should be aware of this rare complication and properly deal with it.
Aged ; Atrial Fibrillation ; therapy ; Catheter Ablation ; adverse effects ; Heart Septum ; injuries ; Humans ; Male ; Middle Aged ; Punctures