AIMTo evaluate the effects of atria-His bundle sequential pacing on cardiac electrophysiology and heamodynamics in dogs.

METHODSIn 20 opening chest anesthetized dogs, platinum electrodes were fixed at the epicardium of right atria (RA) and the right ventricular apex (RVA) respectively, pacing right atria and the right ventricle. A special lead was located at His bundle (based on a optical "H" wave and narrow duration of the QRS complexes recorded in ECG), pacing His bundle. Cardiac electrophysiology and hemodynamics parameters were compared in the different pacing models RA(AAI, RVA-(VVI), HisB-(VVI) single chamber pacing and RA-RVA(DDI), RA-HisB(DDI) dual chamber pacing.

RESULTSThe threshold of His B pacing is similar to that of RVA pacing. Cardiac output (CO) is increased in pacing of RA(AAI), His B-(VVI) and RA-His B(DDI). It is increased by 29.64% in pacing of RA-His B(DDI) (P < 0.01) and by 0.25% (P > 0.05) in pacing of RA-RVA(DD1) While CO is decreased by 5.41% in RVA-VVI) pacing (P > 0.05). SV, LVSW and RVSW of RA-HisB(DDI) pacing are superior to those in RVA-VVI) and RA-RVA(DDI) pacing.

CONCLUSIONRight atria-His bundle sequence pacing significantly improves cardiac function compared with the other model pacing because it maintains normal physiological electronic activity sequence and systolic synchrony. It will be adapted to clinical application.

Animals ; Bundle of His ; physiology ; Cardiac Electrophysiology ; Cardiac Pacing, Artificial ; methods ; Dogs ; Female ; Heart Atria ; Hemodynamics ; Male

Body surface potential map, an electric potential distribution on the body torso surface, enables us to infer the electrical activities of the heart. Therefore, observing electric potential projected to the torso surface can be highly useful for diagnosing heart diseases such as coronary occlusion. The BSPM for the heart of a patient show a higher level of sensitivity than 12-lead ECG. Relevant research has been mostly based on clinical statistics obtained from patients, and, therefore, a simulation for a variety of pathological phenomena of the heart is required. In this study, by using computer simulation, a body surface potential map was implemented according to various occlusion locations (distal, mid, proximal occlusion) in the left anterior descending coronary artery. Electrophysiological characteristics of the body surface during the ST segment period were observed and analyzed based on an ST isointegral map. We developed an integrated system that takes into account the cellular to organ levels, and performed simulation regarding the electrophysiological phenomena of the heart that occur during the first 5 minutes (stage 1) and 10 minutes (stage 2) after commencement of coronary occlusion. Subsequently, we calculated the bipolar angle and amplitude of the ST isointegral map, and observed the correlation between the relevant characteristics and the location of coronary occlusion. In the result, in the ventricle model during the stage 1, a wider area of ischemia led to counterclockwise rotation of the bipolar angle; and, during the stage 2, the amplitude increased when the ischemia area exceeded a certain size.
Cardiac Electrophysiology* ; Computer Simulation* ; Coronary Occlusion ; Coronary Vessels* ; Electrocardiography ; Electrophysiological Phenomena ; Electrophysiology ; Heart ; Heart Diseases ; Humans ; Ischemia ; Torso

The ability to map and ablate the sometimes fleeting automatic atrial tachycardia is greatly enhanced by computerized mapping systems. In this study, we have developed 128 channel computerized data analysis system using microcomputer for basic research of electrophysiology and electrical propagation. The bipolar electrogram information is acquired from 128 cardiac sites simultaneously at a sampling rate of 1 ksampls/sec with continuous and total data storage of up to 30 seconds. When the reference electrogram is selected and reference point is picked up, delay time from the reference point is displayed on three dimensional diagram of the heart. System design permits easy expansion to almost 256 simul- taneous sites. This system is expected to enable us to study pathophysiology of cardiac arrhythmia and to improve the result of diagnosis and surgical treatment for cardiac arrhythmia.
Arrhythmias, Cardiac ; Diagnosis ; Electrocardiography* ; Electrophysiology ; Heart ; Information Storage and Retrieval ; Microcomputers ; Statistics as Topic ; Tachycardia

Non sinus focal atrial tachycardia (AT) is an uncommon arrhythmia. Electrocardiograms (ECGs) can be used to diagnose the condition. ECGs can also be used to pinpoint the origin of the focal AT; however, the precise location is ultimately confirmed by electrophysiology. Automaticity, triggered activity, and micro-reentry are possible underlying mechanisms for focal AT. Pharmacological therapy is recommended for symptomatic patients. Radiofrequency catheter ablation is a viable alternative, especially in patients intolerant to drugs, or patients with drug-refractory focal AT. This review describes the epidemiology, clinical features, diagnosis, and mechanisms of focal AT, as well as possible therapeutic approaches for this condition.
Arrhythmias, Cardiac ; Catheter Ablation ; Diagnosis ; Electrocardiography ; Electrophysiology ; Epidemiology ; Humans ; Tachycardia* ; Tachycardia, Ectopic Atrial

BACKGROUND: Radiofrequency(RF) catheter ablation has been widely and successfully employed to cure young adult and old aged patients of a variety of arrhythmias. Only limited data exist which compare the results in two groups. The aim of this study was to compare the efficacy and safety of RF catheter ablation in old-aged patients(Group 1. older than 65 years old) versus young adult patients(Group 2. younger than 65 years old). METHOD: Clinical and electrophysiologic data were reviewd retrospectively in 385 patients who underwent radiofrequency catheter ablation from December. 1997 through May 2004. Procedure ralated results were used to compare 2 groups RESULTS: Mean age of each groups was 68.4+/-3.37 in group 1 versus 37.5+/-14.04 in group 2. There was no difference between two groups in gender, types of tachyarrhythmia, success rate, rate of complication and recurrence. No severe complications, such as death, vascular dissection, rupture, and major cerebrovascular accidents were present in either group. Procedure related variables, including fluroscopic time, were similar between 2 groups. CONCLUSION: RF catheter ablation is a safe and feasible primary treatment method for tachyarrhythmia in elderly patients, results similar to those achived with younger patients.
Aged* ; Arrhythmias, Cardiac ; Catheter Ablation* ; Electrophysiology ; Humans ; Recurrence ; Retrospective Studies ; Rupture ; Stroke ; Tachycardia* ; Young Adult

BACKGROUND: Radiofrequency(RF) catheter ablation has been widely and successfully employed to cure young adult and old aged patients of a variety of arrhythmias. Only limited data exist which compare the results in two groups. The aim of this study was to compare the efficacy and safety of RF catheter ablation in old-aged patients(Group 1. older than 65 years old) versus young adult patients(Group 2. younger than 65 years old). METHOD: Clinical and electrophysiologic data were reviewd retrospectively in 385 patients who underwent radiofrequency catheter ablation from December. 1997 through May 2004. Procedure ralated results were used to compare 2 groups RESULTS: Mean age of each groups was 68.4+/-3.37 in group 1 versus 37.5+/-14.04 in group 2. There was no difference between two groups in gender, types of tachyarrhythmia, success rate, rate of complication and recurrence. No severe complications, such as death, vascular dissection, rupture, and major cerebrovascular accidents were present in either group. Procedure related variables, including fluroscopic time, were similar between 2 groups. CONCLUSION: RF catheter ablation is a safe and feasible primary treatment method for tachyarrhythmia in elderly patients, results similar to those achived with younger patients.
Aged* ; Arrhythmias, Cardiac ; Catheter Ablation* ; Electrophysiology ; Humans ; Recurrence ; Retrospective Studies ; Rupture ; Stroke ; Tachycardia* ; Young Adult

The incidence of intraoperative arrhythmia is extremely high, and some arrhythmias require clinical attention. Therefore, it is essential for the anesthesiologist to evaluate risk factors for arrhythmia and understand their etiology, electrophysiology, diagnosis, and treatment. Anesthetic agents reportedly affect normal cardiac electrical activity. In the normal cardiac cycle, the sinoatrial node initiates cardiac electrical activity through intrinsic autonomous pacemaker activity. Sequential atrial and ventricular contractions result in an effective cardiac pumping mechanism. Arrhythmia occurs due to various causes, and the cardiac pumping mechanism may be affected. A severe case may result in hemodynamic instability. In this situation, the anesthesiologist should eliminate the possible causes of arrhythmia and manage the condition, creating hemodynamic stability under proper electrocardiographic monitoring.
Anesthesia ; Anesthetics ; Arrhythmias, Cardiac* ; Diagnosis ; Electrocardiography ; Electrophysiology ; Hemodynamics ; Incidence ; Risk Factors ; Sinoatrial Node

Atrial fibrillation (AF) is most common arrhythmia and its prevalence appears to be increasing as the population ages. Echocardiography can play a key role in risk stratification and management of patients with AF. Transthoracic echocardiography allows rapid and comprehensive assessment of cardiac anatomical structure and function. Pulmonary vein flow monitoring using echocardiography has the potential to an increasing role in the evaluation of cardiac function and AF ablation procedures. Transesophageal echocardiography also provides accurate information about the presence of a thrombus in the atria and thromboembolic risk. The novel technique of intracardiac echocardiography has emerged as a popular and useful tool in the everyday practice of interventional electrophysiology. Other imaging modalities, such as computed tomography and magnetic resonance imaging have complementary roles in risk stratification and assessment of patients with AF. Echocardiography continues to be the foundation of clinical evaluation and management of AF.
Arrhythmias, Cardiac ; Atrial Fibrillation ; Echocardiography ; Echocardiography, Transesophageal ; Electrophysiology ; Humans ; Magnetic Resonance Imaging ; Prevalence ; Pulmonary Veins ; Thrombosis

PURPOSE: Anthracycline induced cardiotoxicity is well known and its pathology is characterized by localized myocardial cell necrosis and myocardial fibrosis. The variability in QT interval duration amongst the different leads of the standard 12-lead ECG(QT dispersion) is considered to reflect inhomogenous repolarization of the myocardium. The aim of this study was to assess the effects of anthracycline on cardiac electrophysiology, with special emphasis on dispersion of QT interval and its relation to cumulative doses. METHODS: Heart rate-corrected QT interval(QTc) and QT dispersion(QTd) were measured in standard 12-lead ECG in 34 cancer patients and compared with those of normal control. RESULTS: QTc was increased in cancer patients(462.2+/-36.0 msec vs 447.0+/-19.7 msec) but QTd was not different between the cancer patients and normal control as a whole(40.8+/-12.5 msec vs 36.6+/-9.2 msec). But in the 5-10 year age group, QTd was increased in cancer patients in comparison with that of age matched control(44.1+/-14.8 msec vs 34.0+/-9.7 msec). Also QTc in the 5-10 year age group, but not in the 11-15 year age group, was increased in cancer patients in comparison with that of age matched control(478.0+/-40.8 msec vs 446.5+/-20.9 msec). QTc and QTd were not different according to the cumulative doses of anthracycline in the cancer patients. Left ventricular systolic function was found normal in all cancer patients by echocardiographic examination. CONCLUSION: In the absence of a significant modification of echocardiographic parameters, increased inhomogeneity of ventricular repolarization could be an early marker of anthracycline cardiotoxicity. The changes of repolarization parameters were significant only in the younger age group and were not significant according to the cumulative doses. Anthracycline seemed to induce cardiotoxity from the small dose and more significantly in the younger heart.
Anthracyclines* ; Cardiac Electrophysiology ; Child* ; Drug Therapy* ; Echocardiography ; Electrocardiography ; Fibrosis ; Heart ; Humans ; Myocardium ; Necrosis ; Pathology

We invented an efficiently approach to building whole-heart electrophysiological model with cellular automata style massive parallel computing. In this paper, we introduce the simulation facilities of a model we built and the potential application of such model. The first use is to solve the forward problem of electrocardiogram. Simulating arrhythmia ECG and accurately interpreting the significance of various irregular waveforms will be the key goal. Investigating the dynamic property of cardioelectrical activity at cellular and channel levels is the second application, aiming at revealing the mechanism of the generation and sustentation of arrhythmia. Third, the model can be used to research the impacts of artificial interventions on cardioelectrical activity. Electrical defibrillation and pace-making as well as the use of channel block agents are all cases.
Arrhythmias, Cardiac ; etiology ; physiopathology ; Computer Simulation ; Electrocardiography ; methods ; Electrophysiology ; Heart ; physiology ; Humans ; Models, Cardiovascular