Effects of Long-term Right Ventricular Apical Pacing on Left Ventricular Remodeling and Cardiac Function

Objective: To investigate the impacts of long-term right ventricular apical pacing on the ventricular remodeling and cardiac functions of patients with high-grade and third-degree atrioventricular blockage with normal heart structures and cardiac functions. In addition, we provide many evidences for choosing an optimal electrode implantation site.Methods: Study participants included patients who were admitted for pacemaker replacements and revisited for examinations of implanted pacemakers at outpatient. Pacemakers were implanted to treat high-grade and third-degree atrioventricular blockage. At the time of pacemaker implantation, patients had normal cardiac functions and showed no serious heart diseases or cardiac dilatation. The durations from the implantation to follow-up were more than 5 years. The pacing rate was higher than 80%. Patients with a left ventricular ejection fraction (LVEF) < 50% and a left ventricular end-diastolic diameter (LVEDD) > 55 mm were excluded. Ventricular remodeling was defined as follows:increase of LVEDD by 10% and a reduction of LVEF by 25% for five years after implantation. Cardiac functions were evaluated according to New York Heart Association (NYHA) classification.Results:A total of 82 patients with a mean age of (66.97±13.19) years (range, 12 to 91 years old),among which 39 male and 43 female were enrolled in this study. The average duration between two assessments was 8.7 years (104.4 months). Before pacemaker implantation, the average left atrial diameter (LA), LVEDD and LVEF were 37.0 mm, 50.23 mm and 64.87%, respectively. After the implantation, these values were 39.39 mm (P=0.000163), 50.82 mm (P=0.177842) and 60.50% (P=0.000104), respectively. Four patients (4.87%) had ventricular remodeling with deteriorations of cardiac function, three of which had anterior wall myocardial infarction after implantation and one had type II diabetes. Clinical symptoms of heart failure were not found among the patients who did not exhibit ventricular remodeling. Conclusion: Through a long-period follow-up study, we found that long-term right ventricular apical pacing in patients with normal heart structure and cardiac function would not generally cause ventricular remodeling and clinical deteriorations of cardiac function. Right ventricular apical is a safe and effective site for pacing electrode wire implantation.

OptiVol fluid index predicts acute decompensation of heart failure with a high rate of unexplained events

Background Intrathoracic impedance monitoring has emerged as a promising new technique for the detection of impending heart failure (HF). Although false positive episodes have been reported in case reports and clinical trials, the efficacy and false positive rate in real-world practice remain unclear. Objective The aim of this study is to investigate the utility and reliability of the OptiVol alert feature in clinical practice. Methods We continuously recruited patients who underwent implantable cardioverter-defibrillator (ICD) or cardiac re-synchronization therapy with defibrillator (CRT-D) implantation with feature of intrathoracic impedance monitoring system in our center from Sep. 2010 to Oct. 2012. Regular in-office follow-up were required of all patients and the following information was collected at each visit: medical history, device interrogation, N-terminal pro-brain natriuretic peptide (NT-proBNP) measurement and an echocardiogram. Worsening HF was defined as hospitalization or the presentation of signs or symptoms of HF. Results Forty three patients (male:76.7%, mean age:57 ± 15 years, left ventricular ejection fraction (LVEF):33%± 14%) were included in this observational study. Fifty four alert events and 14 adjudicated worsening HF were detected within 288 ±163 days follow-up. Eleven (20.4%) alert episodes were associated with acute cardiac decompensation in 9 patients with a positive predictive value of 78.6%. Forty three audible alerts showed no connection to worsening HF. The unexplained alerts rate was 79.6%and 1.27 per person-year. Thirty seven alarm alerts were detected in patients with EF<45%, among which 9 accompanied with HF, 17 alerts detected in patients with LVEF≥45%and 2 associated with HF. There was no sig-nificant difference between the two groups (9/37 vs. 2/17;P=0.47). Conclusions Patients with normal or nearly normal left ventricular systolic function also exhibited considerable alert events. The OptiVol fluid index predicted worsening cardiac events with a high unex-plained detection rate, and any alert must therefore be analyzed with great caution. Efforts to improve the specificity of this monitoring sys-tem represent a significant aspect of future studies.

Long-term follow-up of right ventricular outflow tract septal pacing

客观恰好室的流出道中隔广泛地变得使用我们一个电极放置地点。然而，有关为与这种技术重新定位的铅的铅表演和复杂并发症的数据是欠缺的。这研究的目的是观察长期的铅表演和恰好室的流出道的复杂并发症氏族的踱步并且为选择一个最佳的电极培植地点提供证据。方法有氏族的活跃电极培植的 36 个病人并且 39 在这研究与顶端的被动电极培植被注册。为在培植和后续的二个组的踱步的阀值，察觉到的 R 波浪，铅阻抗，踱步的 QRS 宽度和步相关的复杂并发症被比较。在那里的结果更高与顶端的组相比在氏族的组在培植正在在阀值和更短的踱步 QRS 宽度上踱步。在之间没有差别氏族并且在在后续期间在阀值， R 波浪敏感，铅阻抗和步相关的复杂并发症上踱步的顶端的组。因为它与传统的顶端的地点相比有长期的稳定的铅表演和没有严肃的复杂并发症，结论恰好室的流出道中隔能为培植地点被用作第一种选择。

RADIOFREQUENCY CATHETER ABLATION OF PERMANENT ATRIAL FIBRILLATION UNDER GUIDANCE OF CARTO-MERGE TECHNIQUE

Objective To investigate the feasibility and effectiveness of radiofrequency catheter ablation (RFCA) to treat permanent atrial fibrillation (AF) under the guidance of Carto-Merge technique. Methods Fifteen male patients with permanent AF underwent RFCA under the guidance of Carto-Merge technique. The mean age was 54.00±10.44 years, and duration of AF was 23.66±14.93 months. Cardiac magnetic resonance angiography (MRA) was performed to obtain pre-procedural three-dimensional (3D) images on the anatomy of left atrium (LA) and pulmonary veins (PVs) before RFCA procedure. Then the electroanatomical map was integrated with 3D images of MRA to form Carto-Merge map that guided step-by-step ablation strategy of permanent AF. Circumferential PV ablation was performed first until complete PVs electric isolation confirmed by Lasso catheter. If AF was not terminated, lesion lines on roof of LA, mitral isthmus, and tricuspid isthmus were produced. Results The episodes of AF were terminated during RFCA in 2 patients, by direct current cardioversion in the remaining 13 patients. Transient AF occurred in 2 patients after ablation on 1st day and 1st week respectively, AF terminated spontaneously not long after taking metoprolol. One patient developed persistent atrial flutter (AFL) in 2 months after procedure and AFL was eliminated by the second ablation. Persistent AF recurred on 1st day, 1st and 5th week respectively in 3 patients, and did not terminate after 3 months even though amiodarone was given. The remaining 12 patients were all free of AF during 2-11 months of follow-up. The recent success rate for RFCA of permanent AF was 80%. Conclusions Carto-Merge technique can effectively guide RFCA of permanent AF. When combined with single Lasso mapping, it can simplify the mapping, lower expenses, and enhance the success rate of RFCA of permanent AF.

Effect of Statins on Preventing Paroxysmal Atrial Fibrillation after Pacemaker Implantation

Objective: To observe the effect of statins on preventing paroxysmal atrial fibrillation (PAF) after pacemaker imlantation in patients with sick sinus syndrome. Materials and Methods: 68 patients were selected in which the pacemakers had been implanted due to sick sinus syndrome,and were randomly divided into a statin treatment group and a control group. After the pacemaker implantation, only the patients in treatment group were given 20 mg atorvastatin once per night,with other conditions basically similar to those in the control group. At the 3rd, 9th, 15th, and 21st months after the implantation, the pacemakers were programmed, and the PAF-related information stored in the pacemaker were recalled and analyzed statistically. Results: After the administration of statins for 9 months since the imlantation, the occurrence rates of PAF in the treatment group was relatively lower than those in the control group. After further administration of statins for 15 months, both the occurrence rate of PAF and the burden of atrial fibrillation in the treatment group had significantly declined. After continuous administration of statins for 21 months, both the occurrence rate of PAF and the burden of atrial fibrillation in the treatment group were significantly lower than those in the control group. Conclusion: Long-term administration of statins can reduce the risk of PAF after the implantation of a pacemaker in patients with sick sinus syndrome.

The automaticity of Mahaim fibre and its response to effective ablation

Background Typical accessory pathways (APs) of Wolf Parkinson White syndrome have been widely discussed in recent decades However, the characteristics of the special AP, Mahaim fibre, are not so clear It is known that these fibres have antegrade conduction only, long conduction time, decremental node like conduction and automaticity properties This study was to elucidate the automaticity of Mahaim fibre and its response to effective ablation Methods Thirteen patients with Mahaim fibre (ten atrioventricular and three atriofascicular accessory pathways) were subjected to electrophysiological study and radiofrequency ablation via catheter The incidence and characteristics of anautomatic rhythm originating from Mahaim fibre were observed during the whole procedure, especially during radiofrequency current delivery Results Repetitive and short run automatic rhythm (rate: 65-72 beats per minute), with a QRS morphology similar to that of clinical pre excited atrioventricular re entrant tachycardia (AVRT), occurred in two patients during sinus rhythm Conduction via Mahaim fibre was successfully eliminated by radiofrequency current Fourteen applications of RF were associated with irregularly accelerated automatic tachycardia of Mahaim fibre (with a sensitivity of 78%), lasting for 1 2-14 seconds However, such automatic tachycardia of Mahaim fibre did not occur during 54 failed applications of radiofrequency current Conclusions Mahaim fibre has the function of automaticity The accelerated automatic tachycardia of Mahaim fibre occur red during radiofrequency catheter ablation can be used as a predictor for successful

Mathematical models of canine right and left atria cardiomyocytes

The aim of this study is to build two mathematical models of canine ionic currents specific to right atria and left atria.The canine left atria mathematical model was firstly modified from the Ramirez-Nattel-Courtemanche(RNC) model using the recently available experimental data of ionic currents and was further developed based on our own experimental data.A model of right atria was then built by considering the differences between right atria and left atria.The two developed models well reproduced the experimental data on action potential morphology,the rate dependence,and action potential duration restitution.They are useful for investigating the mechanisms underlying the het-erogeneity of canine regional action potentials and would help the simulation of whole heart excitation propagation and cardiac arrhythmia in the near future.

Optimized cardiac resynchronization therapy in patients with congestive heart failure

Heart failure was a major and increasing public healthproblem, with an almost 'epidemic' increase in thenumber of patients. Despite recent advances inpharmacotherapy, the prognosis remains poor. Cardiacresynchronization therapy (CRT), by pacing right and leftventricles, has been proved to improve symptoms andreduce mortality for heart failure patients with cardiacdyssynchrony. However, 20% to 30% of patients didnot respond to CRT. The good cardiac synchronicitybefore CRT and the remaining atrioventricular,