Expression of PDGFR-α in Patients with Valvular Atrial Fibrillation

Objective: To investigate the expression of Platelet-derived growth factor receptor alpha (PDGFR-α) in patients who have valvular atrial fibrillation. Methods: In this research, eighty-four patients with rheumatic heart disease who were going to undertake cardiac surgery were included. The subjects were divided into two groups: the AF group and the sinus rhythm group, the quantities are 39 and 45 respectively. Before the surgery, baseline demographics, physical examination, routine laboratory testing, echocardiography, echocardiographic data and additional clinical data were available for all patients. The right atrial tissue of the subjects was separated during surgery, with an area of approximately 0.3 - 0.5 mm3. Immunofluorescence staining was used to analyze the distribution of PDGFR-α of atrial tissue. mRNA of PDGFR-α in atrial tissue were determined by real-time quantitative PCR (Polymerase Chain Reaction);Western-Blot technique was used to measure the protein of PDGFR-α in atrial tissue. Results: There were no significant differences (P > 0.05) in sex ratio, age, blood pressure, blood biochemistry, and other aspects of medical history between the two groups. However, the right and left atrium diameters in the AF group were markedly larger than those in the SR group (P α from right atrial tissue were obviously higher in the AF group than that in the SR group (P Conclusion: The expression of PDGFR-α in the right atrial tissue of patients with atrial fibrillation was found to be significantly higher.

Autonomic mechanism for chronic atrial electrical remodeling induced by rapid atrial pacing in ambulatory danines

Objetives The mechanism for changes in the electrophysiological properties of the atria during rapid pacing induced atrial fibrillation(AF) is not well understood.We aimed to investigate the contribution of intrinsic cardiac autonomic nervous system(ICANS) in chronic atrial electrical remodeling and AF induced by rapid atrial pacing for 4 weeks. Methods Twelve adult mongrel dogs weighing 15 to 20 kg were assigned to two groups;group 1(experimental group,n= 7) and group 2(control group,n =5).All dogs were anesthetized with propofol and mechanically ventilated via endotracheal tubes.The chest was entered via bilateral mini-thoracotomy at the fourth intercostals space.Bipolar pacing electrode was sutured to the right atrial appendage.Four-electrode catheters(Biosense-Webster,Diamond Bar,CA) were secured to allow recording at the right and left atriaum.All tracings from the electrode catheters were amplified and digitally recorded using a computer-based Bard Laboratory System (CR Bard Inc,Billerica,MA).Electrograms were filtered at 50 to 500 Hz.Continuous rapid pacing(600 bpm, 2×threshold[TH]) was performed at the right atrial appendage. Ganglionated Plexi(GP) was localized by applying high frequency stimulation(HFS;20 Hz,0.1ms duration, 0.5 to 4.5 V)with a bipolar stimulation-ablation probe electrode (AtriCure,West Chester,OH).Group1 underwent ablation of bilateral GP and ligament of Marshall followed by 4-week pacing.Group 2 underwent sham operaton without ablation of GP and ligament of Marshall followed by 4-week pacing.The effective refractory period(ERP) and window of vulnerability(WOV) were measured at 2×TH before(baseline) and every week after GP ablation.WOV was defined as the difference between the longest and the shortest coupling interval of the premature stimulus that induced AF.GP consist of the anterior right ganglionated plexi(ARGP) located in the fat pad at the right superior pulmonary vein(RSPV)-atrial junction;the inferior right ganglionated plexi(IRGP) located at the inferior vena cava/right atrial junction;the superior left ganglionated plexi(SLGP) at the left superior pulmonary vein(LSPV) /left atrial junction and the inferior left ganglionated plexi(ILGP) at the left inferior pulmonary vein (LIPV)/left atrial junction.Results Immediately after ablation, the ERP in Group 1 became markedly longer and started to shorten gradually during the first 2 weeks,then stabilized at the 4th week.Compared to Group2,the ERP of Group1 was significantly longer in the first 3 weeks(P【 0.05),but no obvious difference at the 4th week in either the right or left atrium(P】0.05).In Group 1,AF could not be induced(WOV=0)in the first 3 weeks after ablation, and at the 4th week,AF was induced in 2 of 7 dogs.In Group2,WOV progressively widened during the 4-week period. AF could not be induced in 5 of 7 dogs in Group 1 and 1 of 5 dogs in Group 2 during the 4-week pacing period. Conclusions The intrinsic cardiac autonomic nervous system (ICANS) plays an important role in the early stage of atrial electrical remodeling induced by rapid atrial pacing.On the other hand,with time passing by,its effect on the formation of AF decreases gradually,which suggests that ICANS may account for a non-dominant factor in the late stage of the rapid pacing-induced chronic atrial fibrillation.

Ionic Remodeling and Direct Effects of Valsartan on Ionic Currentsin Human Atrial Myocytes with Atrial Fibrillation

Objectives Previous studies demonstrated that angiotensin receptor antagonists had effects on some potassium channels in guinea pig myo- cytes and cloned channels that expressed in human car- diac myocytes. This study determined the direct effects of Valsartan on IcaL, INa, IKur, IKl and Itol in isolated human atrial myocytes. Methods and Results Specimens of right atrial appendage tissue were ob- tained from 39 patients with coronary artery and valvu- lar heart diseases during cardiopuhnonary bypass proce- dure. Pre - operation cardiac rhythm was sinus (SR) in 19 patients and was atrial fibrillation (AF) in the others. Single atrial myocyte was isolated by enzymatic dissociation with the chunk method. The ionic currents were recorded using the whole cell configuration of the voltage clamp technique. ICaL and Itol densities in AF patients were significantly lower than those in SR pa- tients by 74% and 60% , respectively, while IK1 density was significantly higher by 34% at command potential of - 120 mV. With 10 μmol/L Valsartan, INa density was significantly decreased by 59% in SR patients and by 66% in AF patients. IKur and IK1 density were sig- nificantly decreased in only AF patients by 31% and 23% , respectively. Conclusions Conclusions De- creased ICaL and Itol and increased IK1 at hyperpolarizing potentials in AF patients' atrial myocytes may result from the electrophysiological remodeling by AF. Val- sartan significantly decreases INa, IK1 and IKur current densities in AF patients' myocyte, but decreases only INa in SR patients' myocyte, suggesting that Valsartanmay be beneficial to the recovering of remolded atria.

Effect of spironolactone on cardiac remodeling after acute myocardial infarction

BACKGROUND:Few studies have reported the effect of aldosterone receptor antagonist(ARA) on myocardial remodeling after acute myocardial infarction(AMI).This study was undertaken to investigate the preventive effect of ARA on myocardial remodeling after AMI.METHODS:A total of 616 patients who had been admitted into the CCU of the First Affiliated Hospital of Harbin Medical University from January 2008 to January 2010 were studied prospectively.Only 528 patients were observed completely,including 266 of the control group and 262 of the treatment group.There was no statistical difference in age,gender,medical history,admission situation,and treatment between the two groups(P>0.05).The preventive effects of spironolactone on cardiac remodeling,left ventricular function,renal function and blood levels of potassium were evaluated by echocardiography,serum potassium and serum creatinine at one-month and one-year follow-up.RESULTS:The echocardiography indicators such as LVESD,LVEDD,LVEF,LAD-ML and LADSI were significantly improved in the treatment group compared with the control group at one year(P<0.05).In the treatment group,LVESD,LVEDD,LVPWT,LVEF,LAD-ML and LAD-SI were more significantly improved at one year than one month(P<0.05,P=0.007 to LVEF),and in the control group LVEF was more significantly improved at one year than one month(P=0.0277).There were no significant differences in serum potassium and serum creatinine levels between the two groups.CONCLUSION:On the basis of conventional treatment,the early combination of low-dose spironolactone(20 mg/d) could inhibit cardiac remodeling at late stage and prevent heart fadure.

The Correlation between sST2 and Atrial Fibrillation and Its Clinical Significance

Objective: To explore the level of soluble growth-stimulated expression gene 2 (sST2) in patients with atrial fibrillation (AF) and its relationship with atrial remodeling. Methods: From December 2018 to July 2019, 86 patients were enrolled in the cardiovascular department of Jingzhou Central Hospital in Hubei Province. AF group was 60 patients with AF diagnosed according to the diagnostic criteria of electrophysiology and pacing branch of Chinese Medical Association, while the control group was 26 normal ECG patients with sinus rhythm examined by ECG and/or DCG. Clinical data, NT proBNP and birth rate of all patients were collected chemical indicators. All the patients in the groups were examined by ECG and color Doppler echocardiography. The serum level of ST2 was detected by enzyme-linked immunosorbent assay (ELISA), and the indexes related to atrial remodeling in echocardiography, left atrial diameter (LAD), were collected, compared and analyzed. Results: Serum sST2 levels and LAD and RAD values in the AF group were higher than those in the control group (P < 0.05 or P < 0.01). Serum sST2 levels were higher in the AF group than in the paroxysmal atrial fibrillation group (P = 0.031). 1) The sST2 level was positively correlated with LAD and RAD measured by cardiac ultrasound (r = 0.388, P = 0.029). Conclusion: Serum sST2 levels have early recognition value in patients with high-risk atrial fibrillation, which contributes to the stratification of risk of atrial fibrillation and the prediction of disease activity. Elevated serum sST2 levels may be associated with atrial remodeling. sST2 may be an objective biomarker that predicts the risk of emergency admission in patients with atrial fibrillation. Elevated sST2 levels may be associated with atrial fibrillation progression.

Clinical utility of left atrial strain in predicting atrial fibrillation recurrence after catheter ablation: An up-to-date review

Rhythm control is the core part of the integrated management of atrial fibrillation(AF),especially in the early stages.Despite advances in catheter ablation(CA),the recurrence rate of AF after CA remains high.As a result,stratification and early management of AF recurrence after CA are critical.Currently,predictors of recurrence of AF after CA are mostly based on dysfunction caused by structural remodeling,apart from traditional risk factors.Atrial strain is a recently developed important parameter for detecting the deformability of atrial myocardium during the cardiac cycle prior to atrial remodeling.Although there is only preliminary evidence,atrial strain is still a promising parameter in predicting the recurrence of AF after CA at an early stage.This review focuses on the evaluation of atrial strain,the current applications of atrial strain in assessing atrial function,and predicting the recurrence of AF after CA.We summarize the contents related as follows:(1)CA for rhythm control in AF;(2)Evaluation methods of atrial strain;(3)Atrial strain in the remodeling and reverse remodeling of AF;and(4)Clinical applications of atrial strain in predicting the recurrence of AF after CA.Although there is accumulating evidence on the role of decreased atrial strain in the early prediction of AF recurrence,atrial strain is limited in clinical practice for lacking exact cut-off values and difficulty in distinguishing specific function phases of the atrium.More research is needed in the future to add strength to the early prediction value of atrial strain in AF recurrences.

Research on Electrical Remodeling After Short Term Pacing in Canine Model

Objectives To evaluate the changes in atrial effective refractory period （AERP） proprieties and in ionic currents in PVs myocytes from dogs subjected to rapid atrial pacing in PVs and right atrial appendage （RAA） and to relate these changes to the ability to induce AF. Methods Twelve mongrel dogs in normal sinus rhythm were paced from the superior left PVs or RAA at 500 bpm for 4 hours. Electrophysiologic studies conducted to determine changes in AERP, dispersion and rhythm. Ionic currents were studies with the patch clamp technique in single PVs myocytes in sham operated dogs and compared with those from PVs pacing and RAA pacing groups. Results The presence of rapid atrial pacing was associated with a marked shortening in AERP in both PVs and RAA pacing group with a marked increase of AERP dispersion in PVs pacing. Both L-type calcium current （Ica L ） and the transient outward current （ Ito ） were reduced in both groups with an increased significance in PVs pacing group. The density of ICa-L was decreased significantly from （ - 6. 03 ± 0. 63 ） pA./pF in the control group to （ -3.21 ±0. 34） pA/pF in PVs pacing group and （ - 4. 75 ± 0. 41 ） pA./pF in RAA pacing group （ n = 6, P 〈 0. 05 ） while the density of Ito was decreased significantly from （8.45 ± 0. 71 ） pA./pF in the control group to （ 5.21 ± 0. 763 ） pA./pF in PVs pacing group and （6. 84 ±0. 69 ） pA./pF in RAA pacing group （ n = 6, P 〈 0. 05 ）. Conclusions Our findings provide likely ionic mechanisms of shortened repolarization in induced atrial tachycardia with a decrease in Ica L and /tocurrent densities which is the likely mechanism for a decrease in Action potential duration （APD） rate adaptation in the canine rapid pacing model more pronounced in PVs pacing group underlying the crucial role of PVs in initiating AF.

Effects of Amiodarone plus Losartan on Electrical Remodeling in Rapid Atrial Pacing in Rabbits

Objectives To investigate the electrical remodeling and the effects of amiodarone and losartan on electrical remodeling in rapid atrial pacing on rabbit model. Methods 40 normal rabbits were randomly divided into 4 groups ： the saline group （control group）, amiodarone group, losartan group, anti ＋ los group. All rabbits were raised drugs in a week. The atrial effective refractory period （AERP） was measured. Then, take a rapid atrial pacing （600 bpm） and the AERP was measured after 0.5, 1, 2, 4, 6 and 8 hours pacing and 30 minutes after the termination of rapid pacing. Results （1） In control group, after 8 hours rapid pacing, AERP200 and AERP150 were significantly shortened 16. 11% ± 3.1% （ P 〈 0. 01 ） and 9. 99 % ± 4. 2% （ P 〈 0. 01 ）. And the degree of AERP shortening induced by rapid pacing was greater at basic cycle lengths of 200 ms （BCL200） than that at BCL150. The AERP of amiodarone, losartan group and ami ＋ los group were not shortened during rapid pacing. （2） In the control group, after the termination of rapid pacing, the AERP gradually increased. The AERP at all of the BCLS examined recovered to almost the 95.78% and 96. 76% of baseline values within the first 10 minutes and recovered to almost the 99.07% and 99.39% of baseline values within the first 30 minutes. Conclusions Short-term atrial rapid pacing can induce the atrial electrical remodeling. Amiodarone and losartan can prevent the electrical remodeling.