This paper applied the Shannon Entropy based on the cross correlation to analyze the epicardial signals from anterior wall of the canine atria. The result demonstrated that during sinus rhythm, the stability level of the correlation among signals from anterior right atria is much higher than the signals from anterior left atria. All the signals from the anterior wall descended when the rhythm changed from sinus rhythm to atrial fibrillation(AF). However, there were some regions still having a stable correlation during AF. The results will be helpful to enhance understanding of the correlation characteristic of AF.
Animals ; Atrial Fibrillation ; physiopathology ; Dogs ; Entropy ; Heart Atria ; physiopathology ; Pericardium ; physiopathology

To evaluate the volume and function of left atrium and left atrial appendage in patients with atrial fibrillation by three-dimensional transesophageal echocardiography and transthoracic echocardiography.
 Methods: A total of 112 patients with atrial fibrillation were divided into two groups: a paroxysmal atrial fibrillation (ParAF) group (n=80) and a persistent atrial fibrillation (PerAF) group (n=32). Control group was people without atrial fibrillation (n=40). Clinical data of the participants were collected. Left atrial dimension (LAD), left atrial volume (LAV), left ventricular end-diastolic volume (LVEDV) and left ventricular end-systolic volume (LVESV) were measured by transthoracic echocardiography, while left atrial appendage peak emptying flow velocity (LAAeV), left atrial appendage peak filling flow velocity (LAAfV), left atrial appendage maximum volume (LAAVmax) and left atrial appendage minimum volume (LAAVmin) were measured by three-dimensional transesophageal echocardiography. Left atrial volume index (LAVI), left ventricular ejection fraction (LVEF) and left atrial appendage ejection fraction (LAAEF) were calculated. 
 Results: Compared with the control group, LAAEF, LAAeV and LAAfV in the ParAF group were decreased obviously, while LAD, LAV, LAVI, LAAVmax and LAAVmin in the ParAF group were increased obviously (P<0.05). Compared with the ParAF group, LAAEF, LAAeV and LAAfV in the PerAF group were also decreased obviously, and LAD, LAV, LAVI, LAAVmax and LAAVmin in the ParAF group were also increased obviously (P<0.05). There was no statistically significant difference in LVEDV, LVESV, LVEF between the ParAF group and the PerAF group (P<0.05).
 Conclusion: Left atrium and left atrial appendage were enlarged and the function of left atrial appendage was declined in patients with AF, and the changes were more obvious in patients with PerAF compared with patients with ParAF by three-dimensional transesophageal echocardiography and transthoracic echocardiography.
Atrial Appendage ; physiopathology ; Atrial Fibrillation ; physiopathology ; Echocardiography, Transesophageal ; Heart Atria ; physiopathology ; Humans

OBJECTIVETo investigate the effects of atrial excitable period (EP) on the stability of atrial fibrillation (AF) in goats.

METHODSTen female goats were instrumented with epicardial electrodes patches on the left atrium (LA) free wall. AF was induced and maintained by a home-made stimulator with frequency of 50 Hz at a 1-second duration and a 2-seconds interval. The stimulator was disconnected regularly. AF-induced duration, average AF cycle length (AFCL), and atrial effective refractory period during AF (ERP(AF)) were measured; EP was calculated by AFCL-ERP(AF).

RESULTSEight goats were studied. Persistent AF (> 24 h) could be induced in all the 8 goats within 6-16 days. When the induced AF lasted for 3-10 min or 24 h, the AFCL was 98.3 ms +/- 11.0 ms and 84.9 ms +/- 5.2 ms (P < 0.05), respectively, ERP(AF) was 90.5 ms +/- 13.2 ms and 63.0 ms +/- 4.8 ms (P < 0.05), respectively, and EP was 7.8 ms +/- 2.4 ms and 21.9 ms +/- 3.5 ms (P < 0.05), respectively.

CONCLUSIONThe decrease in ERP(AF) is more significant than the shortening in AFCL, resulting in the gradually widening of EP which may contribute to the perpetuation of AF.

Animals ; Atrial Fibrillation ; physiopathology ; Disease Models, Animal ; Electrocardiography ; Female ; Goats ; Heart Atria ; physiopathology

Angiotensin Receptor Antagonists ; Atrial Fibrillation ; physiopathology ; Heart Atria ; cytology ; physiopathology ; Humans ; Membrane Potentials ; Receptors, Angiotensin ; agonists

PURPOSETo evaluate and compare the effects of heart rate on conduction velocity in the cavotricuspid isthmus (CTI) and septum in patients with and without typical atrial flutter (AF) using electro-anatomic mapping (EAM) of the right atrium (RA).

METHODSTen patients (age 53+/-10 yrs, 7M/3F) with AF and 13 patients (age 51+/-11 yrs, 5M/8F) with atrioventricular nodal reentrant tachycardia (AVNRT) underwent conventional electrophysiological study, electro-anatomic mapping and radiofrequency ablation. Using EAMs obtained during coronary sinus pacing at pacing cycle length (PCL) 600 ms, 400 ms, and 300 ms, we evaluated conduction velocities in the CTI and septum of RA in 10 patients with AF and compared EAMs to 13 patients with AVNRT to determine whether the conduction slowing required to maintain AFL was related to changes in volume alone or altered RA electrophysiology.

RESULTSConduction velocities in CTI and septum were significantly slower at all PCL when AF was compared to AVNRT (*P<0.05). Additionally, in the AF group, septal conduction velocities were slower at PCL 600 ms and 400 ms, but not at 300 ms compared to CTI (*P<0.05). In AF, during PCL 300, conduction in CTI slowed significantly compared to PCL 600 and 400 ms such that there was no difference between CTI and septum at PCL 300.

CONCLUSIONSThere is slower conduction in the septum compared to the CTI in all patients. However, in patients with AF, there is significant slowing of conduction in the CTI and septum as well as decremental rate-dependent slowing of conduction in the CTI. These findings indicate that in addition to RA enlargement, changes in atrial electrophysiology distinguish AF patients from patients with AVNRT.

Adult ; Atrial Flutter ; physiopathology ; Female ; Heart Atria ; physiopathology ; Heart Conduction System ; physiopathology ; Heart Rate ; physiology ; Humans ; Male ; Middle Aged ; Tachycardia, Atrioventricular Nodal Reentry ; physiopathology ; Tricuspid Valve ; physiopathology

OBJECTIVETo evaluate the nerve remodeling induced by 48 hours right atrial pacing in a canine model.

METHODSRapid right atrial pacing (600 beats/min) was performed in 6 mongrel dogs of either sex for 48 hours to induce sustained atrial fibrillation (AF). Six dogs without pacing served as controls. Cardiac nerves were immunocytochemically stained using anti-growth-associated protein 43 (GAP43) and anti-choline acetyltransferase (CHAT) antibodies to compare nerve sprouting and pneumogastric nerve remodeling between the 2 groups.

RESULTSIn dogs with AF, the GAP43-positive and CHAT-positive nerve densities in the left atrium, left auricular appendage, right atrium and right auricular appendage were significantly higher than in control animals (all P < 0.05). Moreover, nerve density was significantly higher in the right atrium than in the left atrium in dogs with AF. Microscopic examinations revealed an inhomogeneous distribution of cardiac nerves.

CONCLUSIONSignificant nerve sprouting and pneumogastric nerve remodeling were evidenced in the right and left atrium in a canine model of sustained AF induced by 48 hours right atrial pacing.

Animals ; Atrial Fibrillation ; physiopathology ; Cardiac Pacing, Artificial ; Disease Models, Animal ; Dogs ; Female ; Heart Atria ; innervation ; physiopathology ; Male ; Vagus Nerve ; physiopathology

There are many differences between cardiac resynchronization therapy (CRT) and conventional pacing therapy in terms of indications and implant techniques. Generally speaking, CRT requires implanting 3 pacing leads in heart failure patients with ventricular dysynchrony. A left ventricular lead is implanted via intravenous coronary sinus. The pacing site of left ventricle has important influence on therapy response. Sometimes open chest implant or other pacing modes are adopted to compensate the anatomical limitation of coronary sinus and its branches. In addition, the pacing sites and modes of right atrium and right ventricle are also under research to further improve CRT response.
Cardiac Pacing, Artificial ; methods ; Electrodes, Implanted ; Heart Atria ; Heart Failure ; physiopathology ; therapy ; Heart Ventricles ; Humans ; Ventricular Dysfunction, Left ; physiopathology ; Ventricular Dysfunction, Right ; physiopathology

Inter atrial block (IAB) is a prevailing cardiac conduction abnormality that is under-recognized in clinical practice. IAB has strong association with atrial arrhythmia, left atrial enlargement, and electromechanical discordance, increasing the risk of atrial fibrillation (AF) and myocardial ischemia. IAB was generally believed to be caused by impaired conduction along the Bachmann bundle (BB). However, there are three other conduction pathways, including the fibers posteriorly in the vicinity of the right pulmonary veins (VRPV), transseptal fibers in the fossa ovalis (FO), and muscular bundles on the inferior atrial surface near the coronary sinus (CS). We hypothesized that the importance of BB on IAB might have been overestimated. To test this hypothesis, various combinations of conduction pathway blocks were simulated based on a realistic human atrial model to investigate their effects on the index of clinical diagnosis standard of IAB using a simulated 12-lead electrocardiogram (ECG). Firstly, the results showed that the BB block alone could not generate typical P wave morphology of IAB, and that the combination of BB and VRPV pathway block played important roles in the occurrence of IAB. Secondly, although single FO and CS pathways play subordinate roles in inter atrial conduction, their combination with BB and VRPV block could also produce severe IAB. In summary, this simulation study has demonstrated that the combinations of different inter atrial conduction pathways, rather than BB alone, resulted in ECG morphology of IAB. Attention needs to be paid to this in future pathophysiological and clinical studies of IAB.
Adult ; Arrhythmias, Cardiac/physiopathology* ; Atrial Fibrillation/physiopathology* ; Computer Simulation ; Coronary Sinus/physiopathology* ; Electrocardiography ; Heart ; Heart Atria ; Humans ; Male ; Models, Anatomic ; Models, Cardiovascular ; Pulmonary Veins/physiopathology*

This paper discusses the law of atrial electrical activity propagation (the timing of signal and the conduction velocity) under the sinus rhythm before and after AF caused by high-frequency electrical stimulation. The paper analyzes how different doses of acetylcholine affect the conductivity of the atrial cells of dogs. This result can also help the diagnoses and treatment of human's AF.
Acetylcholine ; pharmacology ; Animals ; Dogs ; Epicardial Mapping ; Heart Atria ; cytology ; drug effects ; physiopathology ; Mechanotransduction, Cellular

Animals ; Cardiac Electrophysiology ; Heart Atria ; innervation ; physiopathology ; Humans ; Vagus Nerve ; physiology