Minimal mass required for induction of a sustained arrhythmia in isolated atrial segments

1962 ◽  
Vol 202 (2) ◽  
pp. 232-236 ◽  
Author(s):  
Theodore C. West ◽  
Jorge F. Landa
Keyword(s):  
Electrical Stimulation ◽  
Left Atrium ◽  
Right Atrium ◽  
Refractory Period ◽  
Left Atrial ◽  
Right Atrial ◽  
Conduction Time ◽  
The Mean ◽  
Minimal Mass ◽  
Experimental Arrhythmia

With the aid of electrical stimulation and a combination of acetylcholine and physostigmine, an experimental arrhythmia was predictably induced in isolated atrial segments from rabbits. The tissue was from either left or right atrium, but was not spontaneously active. It was driven electrically at the rate of 2/sec. After the measurement of excitability and of conduction time, both in the presence and absence of ACh, an arrhythmia was induced. The tissue then was divided surgically and the procedure repeated until a residual segment was obtained which did not respond with an arrhythmia. The weight of the nonarrhythmic segment was determined and averaged 32 mg in 16 left atrial preparations, 28 mg in 10 right atrial segments, and 38 mg in 4 segments of left atrium from rabbits chronically treated with reserpine. Calculation of the mean conduction time and of the mean refractory period associated with induction of the experimental arrhythmia indicated that the observed minimal arrhythmic segment was approximately the mass theoretically required if the initiation and maintenance of the arrhythmia were dependent on re-entry excitation.

scholarly journals The Value of Voltage Histogram Analysis Derived Right Atrial Scar Burden in the Prediction of Left Atrial Scar Burden

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Szilvia Herczeg ◽  
Joseph Galvin ◽  
John J. Keaney ◽  
Edward Keelan ◽  
Roger Byrne ◽  
...  
Keyword(s):  
Left Atrium ◽  
Right Atrium ◽  
Low Voltage ◽  
Histogram Analysis ◽  
Right Atrial ◽  
Analysis Tool ◽  
Invasive Treatment ◽  
Scar Burden ◽  
Tissue Burden ◽  
The Right

Introduction. Growing evidence suggests that fibrotic changes can be observed in atrial fibrillation (AF) in both atria. Quantification of the scar burden during electroanatomical mapping might have important therapeutic and prognostic consequences. However, as the current invasive treatment of AF is focused on the left atrium (LA), the role of the right atrium (RA) is less well understood. We aimed to characterize the clinical determinates of the RA low-voltage burden and its relation to the LA scaring. Methods. We have included 36 patients who underwent catheter ablation for AF in a prospective observational study. In addition to LA mapping and ablation, high-density RA bipolar voltage maps (HD-EAM) were also reconstructed. The extent of the diseased RA tissue (≤0.5 mV) was quantified using the voltage histogram analysis tool (CARTO®3, Biosense Webster). Results. The percentage of RA diseased tissue burden was significantly higher in patients with a CHA2DS2-VASc score ≥ 2 p=0.0305, higher indexed LA volume on the CTA scan and on the HD‐EAM (p=0.0223 and p=0.0064, respectively), or higher indexed RA volume on the HD‐EAM p=0.0026. High RA diseased tissue burden predicted the presence of high LA diseased tissue burden (OR = 7.1, CI (95%): 1.3–38.9, p=0.0145), and there was a significant correlation of the same (r = 0.6461, p<0.0001). Conclusions. Determining the extent of the right atrial low-voltage burden might give useful clinical information. According to our results, the diseased tissue burden correlates well between the two atria: the right atrium mirrors the left atrium.

Postnatal Development of a Left-Right Atrial Pressure Gradient

1956 ◽  
Vol 186 (3) ◽  
pp. 521-524 ◽  
Author(s):  
A. van Harreveld ◽  
F. E. Russell
Keyword(s):  
Left Ventricle ◽  
Pressure Gradient ◽  
Left Atrium ◽  
Postnatal Development ◽  
Right Atrial ◽  
Left And Right ◽  
The Mean ◽  
The Right ◽  
The Relationship ◽  
Equal Thickness

The mean left and right atrial pressures were measured in six groups of 10 kittens each. One group was examined between the 12th and 24th hour after birth, one group after 3 days, after 1 week, 2 weeks, 1 month and 2 months. The left and right atrial pressures were almost equal in the first group. With age an increasing left to right pressure gradient developed. In the oldest group the pressure in the left atrium was almost twice as great as in the right. Parallel with the pressure gradient a difference developed in the wall thicknesses of the left and right ventricles. At birth the ventricular walls were of about equal thickness; at age 2 months the left ventricle wall was more than twice as thick as the right. The relationship between ventricle wall thicknesses and atrial pressures is discussed.

Cardioscopic Trans-septal Cryoablation of Left Atrium in Nonmitral Cases

2005 ◽  
Vol 1 (1) ◽  
pp. 48-50 ◽  
Author(s):  
Toshiya Ohtsuka ◽  
Mikio Ninomiya ◽  
Taisei Maemura
Keyword(s):  
Coronary Artery ◽  
Left Atrium ◽  
Tricuspid Regurgitation ◽  
Left Atrial ◽  
Artery Bypass ◽  
Aortic Disease ◽  
Maze Procedure ◽  
Partial Sternotomy ◽  
The Mean ◽  
Asd Closure

Background A modified maze procedure in which trans-septal cardioscopy was used for cryoablation in the left atrium is described. Methods The technique was used in 11 consecutive patients (9 men and 2 women, 56.5 ± 19.8 years) with permanent atrial fibrillation (Af) and concomitant nonmitral cardiac or aortic disease: aortic valvular disease in 4 patients, atrial septal defect (ASD) in 2 patients, tricuspid regurgitation in 2 patients, acute aortic dissection in 1 patient, arch aneurysm in 1 patient, and coronary artery disease in 1 patient. The mean Af duration detected in 7 cases was 18.5 ± 10.1 months. Partial sternotomy was used in aortic valve replacement, ASD closure, and tricuspid valve plasty, and fullsternotomy was used in aortic graft replacement and coronary artery bypass. Cardiopulmonary bypass was established, aortic cross-clamp was performed, a right atriotomy was created, a cryoablation probe and cardioscope (3 mm) were introduced into the left atrium through a 1-cm cut at the fossa ovalis or ASD, and cardioscopic left-atrial endocardial cryoablation was performed. The right-side maze procedure was conducted directly. The atrial appendages were excised in each case. Results Left-atrial cardioscopic cryoablation required 25.0 ± 5.5 minutes, and no deaths or procedure-related morbidities occurred. The mean follow-up period was 12 ± 8.5 months. One patient with tricuspid regurgitation died of liver failure. With the exception of coronary and acute dissection cases, all patients have maintained a sinus rhythm. Conclusion Although experience is limited, videocardioscopic trans-septal left-atrial cryoablation is a viable method for nonmitral Af cases, and the partial sternotomy approach can be performed.

Studies on hexactinellid sponges. II. Excitability, conduction and coordination of responses in rhabdocalyptus dawsoni (lambe, 1873)

1983 ◽  
Vol 301 (1107) ◽  
pp. 401-418 ◽  
Keyword(s):  
Electrical Stimulation ◽  
Refractory Period ◽  
Conduction System ◽  
Conduction Time ◽  
Pumping Power ◽  
Chemical Signalling ◽  
Conduction Pathway ◽  
Electrical Impulses ◽  
Effector Response ◽  
Hexactinellid Sponges

Rhabdocalyptus can arrest its feeding current. The response is initiated by mechanical or electrical stimulation, and is coordinated through the sponge by a conduction system, having a precise excitability threshold and conducting on an all-or-none basis. All parts are excitable and conduct. Individuals in colonial assemblages are coordinated. Spontaneous as well as evoked arrests are observed. There is evidence of scattered pacemaker sites. Conduction is diffuse and unpolarized, and occurs with a velocity of 0.26 ± 0.07 cm s -1 at 11 °C. The conduction system is probably the trabecular syncytium. Isolated dermal membrane (‘pure’ trabecular tissue, without flagella or contractile elements) conducts. Mechanical and chemical signalling mechanisms are discussed. It is concluded that they cannot account for the phenomena observed, but that conduction must involve electrical impulses. The effectors responsible for current arrests are almost certainly the flagella of the flagellated chambers. It is assumed that they stop beating on receiving an arrest signal through the conduction pathway. The waveforms of arrests recorded with a thermistor flowmeter are best interpreted in terms of sudden, all-or-none cessation of pumping, with slow, gradual recovery of full pumping power. The flagella probably beat feebly at first on becoming active again following an arrest. The effector response shows a refractory period of 30 s. Responses occur with short latency. Delays are attributable to conduction time. The system is fatigueable. Numerous parallels exist with the behaviour of the stigmatal cilia in the ascidian branchial sac, both in the characteristics of the effector response and in the mechanism of coordination.

scholarly journals Measurement of Right Atrial Volume and Diameters in Healthy Nepalese with Normal Echocardiogram

2015 ◽  
Vol 12 (2) ◽  
pp. 110-112
Author(s):  
DB Karki ◽  
S Pant ◽  
SK Yadava ◽  
A Vaidya ◽  
DK Neupane ◽  
...  
Keyword(s):  
Right Atrium ◽  
Right Atrial ◽  
Short Axis ◽  
Atrial Volume ◽  
Western Population ◽  
The Mean ◽  
The Right ◽  
Right Atrial Volume ◽  
Echocardiographic Findings ◽  
Volume Size

Background The size of right atrium is expected to be different in diverse healthy ethnic groups. It is important to know the normal size of right atrium in our healthy population.Objective The study aimed to find out the normal values of right atrial volume, right atrial short axis diameter and right atrial long axis diameter in healthy Nepalese population with normal echocardiographic findings. It also looked at correlations between right atrial dimensions and the right atrial volume.Method Verbal consent was taken from all the participants. One hundred participants between the age of 18 and 60 years with normal echocardiographic findings and without any chronic disease were included in this study. Right atrial volume was measured by using area length method. Right atrial short axis diameter and Right atrial long axis diameter were measured in the four chamber view.Result The mean right atrial volume was 23.64±5.36 ml (range 11.30 - 40.00 ml).The range of right atrial short axis diameter and right atrial long axis diameter were 1.34-3.80 cm and 2.4-4.7 cm respectively.Conclusion The size of right atrium in the Nepalese population is smaller compared to western population. Male right atrial volume size is greater than female in Nepalese population similar to western population. The findings of normal value of right atrial volume and right atrial diameter in Nepalese population will help the physician to assess patients with various conditions affecting the right atrium.Kathmandu University Medical Journal Vol.12(2) 2014: 110-112

scholarly journals Giant Left Atrial Myxoma Presenting with Cough-Syncope Syndrome

2021 ◽  
Vol 24 (4) ◽  
pp. E7090-E712
Author(s):  
Esra Ertürk tekin
Keyword(s):  
Mitral Valve ◽  
Left Ventricle ◽  
Left Atrium ◽  
Left Atrial ◽  
Interatrial Septum ◽  
Atrial Myxoma ◽  
Transesophageal Echocardiogram ◽  
Left Atrial Myxoma ◽  
Cardiac Surgeon ◽  
The Mean

We report the case of a 41-year-old female patient with symptoms of cerebrovascular accident manifesting with loss of consciousness during episodes of cough. Computed multislice chest tomography showed a 7.3- by 4.15-cm mass in the left atrium. A transesophageal echocardiogram showed a giant mass in the left atrium that passed through the mitral valve to the left ventricle, and severe obstructive stenosis was suggested by the mean transmitral gradient. After a comprehensive assessment of the mass, we decided to perform surgery. The pedunculated and fragile mass was attached to the interatrial septum with its handle, and the majority of it prolapsed through the mitral valve to the left ventricle and became stacked among the mitral valve leaflets. The removed mass was analyzed histopathologically and was found to be a myxoma. It is important for the cardiac surgeon to surgically remove an atrial myxoma because of the risks associated with embolization, including sudden death, as myxoma can block the blood supply from the atrium to the ventricle.

Cardiac responses to electrical stimulation of discrete loci in canine atrial and ventricular ganglionated plexi

1990 ◽  
Vol 259 (5) ◽  
pp. H1365-H1373 ◽  
Author(s):  
C. K. Butler ◽  
F. M. Smith ◽  
R. Cardinal ◽  
D. A. Murphy ◽  
D. A. Hopkins ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Right Ventricular ◽  
Left Atrial ◽  
Right Atrial ◽  
Intramyocardial Pressure ◽  
Cardiac Responses ◽  
Ganglionated Plexi ◽  
The Right ◽  
Ganglionated Plexus ◽  
Stimulation Of

The purpose of the present study was to examine cardiac effects induced by electrical stimulation (1-4 V, 1 ms, 200 Hz) of discrete loci within the ganglionated plexi located on canine atria and ventricles. When 20 loci in the right atrial ventral ganglionated plexi of 11 anesthetized open-chest dogs were stimulated, bradycardia and/or right and left atrial force suppression occurred when, on average, 15% of these loci were stimulated. Bradycardia and atrial force suppression were elicited when, on average, 8% of 15 loci in the left atrial ventral ganglionated plexi of eight dogs was stimulated. When these loci were restimulated after acute decentralization, cardiac responses were attenuated or occasionally eliminated. After atropine (1 mg/kg iv) administration, repeat stimulation of loci in the right but not left atrial ganglionated plexus induced tachycardia. Stimulation of loci in the right ventricular ganglionated plexus after the subsequent administration of desipramine (1 mg/kg iv) in six dogs resulted in an increase in right ventricular conus intramyocardial pressure. After hexamethonium administration (10 mg/kg iv, followed by a continuous infusion of 1 mg.kg-1.min-1), sympathetic responses were no longer elicited from one of the five dogs in which loci in the right atrial ganglionated plexi and from two of the six dogs in which loci of the right ventricular ganglionated plexus had elicited responses. We conclude that atrial and ventricular ganglionated plexi contain efferent parasympathetic, efferent sympathetic, and afferent neurons.

scholarly journals Increased FDG uptake in AF individuals suggesting atrial inflammation visualized by FDG PET/CT with glucose uptake suppression protocols

2021 ◽  
Vol 42 (Supplement_1) ◽  
Author(s):  
J Kupusovic ◽  
M Weber ◽  
L Kessler ◽  
E Pesch ◽  
L Riesinger ◽  
...  
Keyword(s):  
Glucose Uptake ◽  
Right Atrium ◽  
Fdg Pet ◽  
Left Atrial ◽  
Right Atrial ◽  
Fdg Uptake ◽  
Pet Ct ◽  
18F Fdg ◽  
The Right ◽  
Fdg Pet Ct

Abstract Background Pathophysiology of atrial fibrillation (AF) is multifactorial. Attention has been drawn towards atrial inflammation underlying arrhythmogenic remodeling. The aim of our study was to evaluate if a specific preparation protocol for positron emission tomography/computed tomography (PET/CT) with 18Fluor-labelled fluorodeoxyglucose (18F-FDG) was capable of detecting atrial hypermetabolism as surrogate for inflammation in AF, with the specific hypothesis that protocols specifically aiming to suppress physiologic glucose metabolism (fasting protocols: inflammation and malignancy preparation) were superior to non-fasting protocols. Methods We conducted a single-center study including n=75 patients with a history of AF and n=75 controls without AF (matched for age, sex and left ventricular systolic function) undergoing three different preparation protocols (each n=25 per group): i.) inflammation, ii.) malignancy and iii.) viability protocol before 18F-FDG-PET/CT. We performed visual analysis of local detectable atrial uptake (figure 1A) and assessed quantitative uptake in predetermined loci of the atria and endocrine adipose tissue (EAT), using maximum standardized uptake values (SUVmax) and target to background ratios (TBR). Results Our analysis of visual atrial 18F-FDG uptake revealed that atrial uptake was exclusively observed in AF patients using the malignancy (13/25 patients) and inflammation (10/25 patients) protocol, while the viability preparation revealed atrial uptake both in AF (n=6 patients) and non-AF patients (n=5 patients). With respect to quantitative measures between AF and non-AF individuals using the inflammation protocol, patients with AF showed significantly higher uptake values in the right atrium (SUVmax: 2.54±0.75 vs. 2.03±0.66, p=0.01); TBR 1.51±0.44 vs. 1.18±0.20, p&lt;0.01), right atrial appendage (SUVmax: 2.44±0.71 vs. 2.02±0.64, p=0.03; TBR: 1.47±0.47 vs. 1.20±0.26, p=0.02) and also in EAT (SUVmax: 1.39±0.46 vs. 1.13±0.40, p=0.04), figure 1B. Despite a trend of higher tracer uptake related to the presence of AF in left atrial structures, no statistical significances could be observed between AF and non-AF individuals. Conclusion This retrospective study demonstrates that protocols specifically designed to suppress physiologic glucose uptake seem to be superior in detecting atrial FDG uptake, which could be indicative of atrial inflammation in AF patients. Based on our results the right atrium seems to be more affected from these changes. These results point towards a potential role of right atrial inflammatory processes in AF pathophysiology besides the established left atrial ectopic triggers. FUNDunding Acknowledgement Type of funding sources: None.

scholarly journals Atypical size and location of a right atrial myxoma: a case report

2017 ◽  
Vol 4 (6) ◽  
pp. 2073
Author(s):  
Sushil Kumar Singhal ◽  
Palash Aiyer ◽  
Vijay Grover ◽  
Vijay Kumar Gupta
Keyword(s):  
Differential Diagnosis ◽  
Case Report ◽  
Left Atrium ◽  
Right Atrium ◽  
Atrial Myxoma ◽  
Right Atrial ◽  
Right Atrial Myxoma ◽  
Intracardiac Tumors ◽  
The Right ◽  
Uncommon Location

Primary intracardiac tumors are rare and approximately 50-55% are myxomas. The majority of myxomas are located in the left atrium. Here We report a case of a large myxoma in the right atrium, which is an uncommon location for this type of tumor who underwent operative intervention with excision of a 9x6 cm multilobulated mass. In this case report, we emphasize the rarity of large myxomas in the right atrium and the difficulty of differential diagnosis given their dimension and location.

Comparison of time- and voltage-dependent K+ currents in myocytes from left and right atria of adult mice

2003 ◽  
Vol 285 (5) ◽  
pp. H1837-H1848 ◽  
Author(s):  
Alan E. Lomax ◽  
Colleen S. Kondo ◽  
Wayne R. Giles
Keyword(s):  
Current Density ◽  
Right Atrium ◽  
Left Atrial ◽  
Right Atrial ◽  
Atrial Myocytes ◽  
Adult Mice ◽  
Voltage Dependent ◽  
Left And Right ◽  
The Right ◽  
Right Atria

Consistent differences in K+ currents in left and right atria of adult mouse hearts have been identified by the application of current- and voltage-clamp protocols to isolated single myocytes. Left atrial myocytes had a significantly ( P < 0.05) larger peak outward K+ current density than myocytes from the right atrium. Detailed analysis revealed that this difference was due to the rapidly activating sustained K+ current, which is inhibited by 100 μM 4-aminopyridine (4-AP); this current was almost three times larger in the left atrium than in the right atrium. Accordingly, 100 μM 4-AP caused a significantly ( P < 0.05) larger increase in action potential duration in left than in right atrial myocytes. Inward rectifier K+ current density was also significantly ( P < 0.05) larger in left atrial myocytes. There was no difference in the voltage-dependent L-type Ca2+ current between left and right atria. As expected from this voltage-clamp data, the duration of action potentials recorded from single myocytes was significantly ( P < 0.05) shorter in myocytes from left atria, and left atrial tissue was found to have a significantly ( P < 0.05) shorter effective refractory period than right atrial tissue. These results reveal similarities between mice and other mammalian species where the left atrium repolarizes more quickly than the right, and provide new insight into cellular electrophysiological mechanisms responsible for this difference. These findings, and previous results, suggest that the atria of adult mice may be a suitable model for detailed studies of atrial electrophysiology and pharmacology under control conditions and in the context of induced atrial rhythm disturbances.

Sign in / Sign up

Export Citation Format

Share Document