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PubMed2000

[Anomalties of the interatrial septum and latent atrial vulnerability in unexplained ischemic stroke in young adults].

Seventy-four consecutive patients (18 to 55 years) underwent programmed atrial stimulation in the investigation of unexplained ischaemic stroke after a full work-up including transoesophageal echocardiography to exclude abnormalities of the interatrial septum (patent foramen ovale and/or atrial septal aneurysm). The parameters recorded during atrial electrophysiological investigation were: the effective atrial refractory period, loco-regional intra-atrial conduction, the index of latent atrial vulnerability and the inducibility by the extrastimulus technique. Seventy five per cent of patients with a patent foramen ovale and/or an atrial septal aneurysm were inducible compared with only 38% of patients with normal interatrial septa on transoesophageal echocardiography (p = 0.001). Fifty two per cent of patients with an anomaly of the atrial septum had latent atrial vulnerability compared with 26% of those with normal transoesophageal echocardiography (p = 0.02). These results confirm the relationship between atrial septal anomalies and latent atrial vulnerability in unexplained ischaemic stroke of young adults.

Adolescent↗
PubMed1977

Evaluation of intracardiac recordings in diagnosis of impulse formation and concealed conduction in atrioventricular nodal bypass tracts.

Invasive electrophysiological studies were performed in 2 symptomatic patients with recurrent arrhythmias in which impulse formation presumably occured within atrioventricular nodal bypass tracts. Case 1 had ectopic beats arising within, or close to, the upper end of a left-sided atrioventricular nodal bypass tract of the type described by Brechenmacher. In addition, this conduction was 'concealed' during sinus rhythm and right atrial pacing because the relatively prolonged right-to-left atrial conduction time allowed right atrial impulses to reach the His bundle via the atrioventricular node before they could do so through the atrioventricular nodal bypass tract. Case 2 had ectopic beats arising in a right-sided atrioventricular nodal bypass tract which did not conduct in either forward or retrograde directions, its presence being detected only when initiating impulses. However, it could not be determined whether this tract was an 'abnormal' atrio-His connection or a 'normal' transitional (atrio-atrioventricular nodal) tract. Though intracardiac studies complement body surface recordings, they should be interpreted with knowledge of their inherent limitations.

Adult↗
PubMed1979

[The direct detection of sinus nodal potentials in man by means of the signal-averaging technique (author's transl)].

In 13 patients in the age range of 34 to 70 years (mean: 53 +/- 10 years), during diagnostic His-bundle investigations, registrations from the sinus nodal area were analyzed with a signal-averaging computer. In 12 patients we were able to get reproducible per-P-potentials with a sino-atrial conduction interval between 56 and 227 ms. The normal sequence of the excitation process from the atrium to the AV node together with the bundle of His and to the ventricles in all patients, and the reproducibility of the signal-averaged pre-P-potentials, which were well outlined from the atrial potential with a reasonable conduction interval, suggest that these signal-averaged pre-P-potentials reflect the sinus nodal activity rather than an ectopic focus. In 5 of 11 comparable cases there was a good correlation between the signal-averaged sino-atrial conduction intervals and those calculated with the extrastimulus technique. In 2 patients this correlation was moderate. The signal-averaging process may be impaired by coarse random noise, frequent atrial or ventricular extrasystoles, and by fluctuations of the baseline of the sinus nodal lead. The fact that the registrations are performed during normal undisturbed sinus rhythm offers a considerable advantage over the extrastimulus technique.

Action Potentials↗
PubMed2003

Multisite atrial pacing for atrial fibrillation prevention: where to go from here?

Atrial fibrillation (AF) is a common arrhythmia associated with stroke, increased mortality and with a negative impact on quality of life. Pharmacologic treatments for AF have not provided long-term relief from arrhythmia recurrence. Multi-site atrial pacing was introduced by Daubert and colleagues about 10 years ago for the treatment of severe atrial conduction delays in patients with sick sinus syndrome. They found that this type of atrial stimulation reduced or prevented AF. Multi-site atrial pacing results in reduction of intra-atrial and interatrial conduction differences and diminishes heterogeneity of refractoriness, i.e. atrial resynchronization. Acute electrophysiological studies have shown that biatrial stimulation reduced AF inducibility. The Dutch Dual-site Right Atrial Pacing for Prevention of Atrial Fibrillation study was a prospective randomized crossover trial comparing the recurrences of AF in dual-site right atrial and single-site high right atrial pacing in patients with symptomatic medically refractory AF, without or with minimal structural heart disease. Patients were randomized to initial dual-site pacing (Group I n = 18) or initial single-site (Group II n = 22) pacing. After 6 months or after a study endpoint was reached patients were crossed over to the other pacing modality.Although, the arrhythmia free intervals were longer for dual-site pacing during both treatments periods (Group I 162 +/- 12 and Group II 114 +/- 15 days) compared to single-site pacing (Group I 143 +/- 16 and Group II 97 +/- 10 days) the difference was not statistically significant (p = 0.061). However, the sequence of the randomized treatment periods had a significant effect on outcome (p < 0.02). Event free intervals (AF > 48 hours requiring electrical cardioversion) were longer during dual-site pacing in both groups compared to single-site stimulation but the difference was statistically not significant (p = 0.055) because of treatment interaction (P < 0.05). To establish the clinical benefits of multi-site pacing for the treatment of patients with medically refractory symptomatic AF, additional prospective randomized studies are needed. Trials with a parallel design are necessary to avoid carry-over effects of different stimulation protocols.

Atrial Fibrillation↗
PubMed1976

Coexisting ventricular and blocked atrial parasystole.

A rare instance showing non-conducted atrial parasystole coexisting with ventricular parasystole is presented and a related subject is briefly discussed. The importance of recognizing parasystole is again emphasized because the ordinary extrasystoles, particularly ventricular in origin, are frequently digitalis-induced, while parasystole, which superficially resembles the ordinary extrasystoles, does not seem to be related to digitalis.

Cardiac Complexes, Premature↗
PubMed2001

Inhomogeneity in the appearance of electrical remodeling during chronic rapid atrial pacing: evaluation of the dispersion of atrial effective refractoriness.

In the present study, the long-term process of progression of electrical remodeling at various atrial sites, which is not well understood, was compared while monitoring continuously the electrophysiologic parameters at multirecording sites in canine atria during continuous atrial burst pacing. A rapid pacing device was implanted in 5 dogs, and continuous atrial burst pacing (400 beats/min) was delivered at the right atrial appendage (RAA). Four pairs of epicardial wire electrodes were sutured on (1) the RAA, (2) Bachmann's bundle (BB), (3) the right atrium close to the inferior vena cava (IVC), and (4) the left atrium (LA). The distal ends of those wires were exteriorized posteriorly and used for pacing and recording. The atrial effective refractory period (AERP), AERP dispersion (AERPd), atrial conduction time (CT) and inducibility of atrial fibrillation (AF) were evaluated during burst pacing for 14 days and during the subsequent 7 days' recovery. The AERP at the LA pacing site was shorter than that at the other sites on day 0. The AERP shortening was greater in the RAA and LA sites than in the BB and IVC sites. The AERPd increased during pacing and reached the maximum level on day 3, and then decreased during the recovery phase. Prolongation of CT tended to be longer between the RAAand IVC sites than that between the other sites. The incidence of AF induction became higher in accordance with the time course of the rapid pacing phase. There was another peak of AF induction on days 7-10. In a canine chronic rapid atrial stimulation model, the progression of electrical remodeling (ie, the shortening of the AERP and the prolongation of the CT) was not homogeneous in both atria, the AERPd showed a temporal increase between days 3 and 7 and matched the increase in AF inducibility at the LA pacing site, the increase in the AERPd was mainly caused by more rapid AERP shortening at the RAA or LA sites, and the LA site always showed a shorter AERP than the other atrial sites in the control state and during the rapid pacing phase, whereas AF inducibility was higher at the LA site than the other sites.

Animals↗
PubMed1982

Electrophysiologic effects of chronic amiodarone therapy in patients with ventricular arrhythmias.

Detailed electrophysiologic studies were performed in nine patients with chronic refractory ventricular arrhythmias before and after 7 to 20 weeks (mean 11 weeks) of amiodarone therapy. The amiodarone dose at the time of the repeat study ranged from 400 to 800 mg/day. The drug reduced the sinus rate (p less than 0.001) and prolonged the sinoatrial conduction time (p less than 0.05) with some prolongation of the corrected sinus node recovery time. Intra-atrial conduction was slightly prolonged both in sinus rhythm and during atrial pacing. Anterograde conduction through the AV node was significantly prolonged both in sinus rhythm (p = 0.001) and during atrial pacing (p less than 0.005), and Wenckebach AV block was seen at significantly lower atrial pacing rates after the drug (p less than 0.005). The HV interval was prolonged both in sinus rhythm (p less than 0.05) and during atrial pacing (p = 0.001), and so was the QRS width during atrial pacing (p less than 0.005) and the QT interval in sinus rhythm (p less than 0.005) and during atrial pacing (p less than 0.005). Significant prolongation of the refractory periods in the atrium, AV node, and ventricular muscle were also seen following the drug. We concluded that the significant electrophysiologic effects of this drug throughout the heart during chronic oral use attest to its clinical effectiveness in patients with atrial and ventricular arrhythmias. With due care and despite its effects on the HV interval and QRS width, it can be used in patients with intraventricular conduction defects complicating severe organic heart disease.

Aged↗
PubMed1975

[Sinus node automaticity and sinoatrial conduction].

In 64 patients so-called sino-atrial conduction time (SACT) was calculated by means of the extrastimulus technique. The normal value of this parameter was 82 plus or minus 18.7 ms (20 patients). Plotting SACT versus heart rate in all patients no correlation could be found. However, in 4 patients with spontaneous variations of the sinus cycle length a short SACT was calculated after long spontaneous intervals and vice verse. These results may indicate that SACT ist frequency-dependent. However, it is not clear whether the behaviour of the postextra-systolic pauses in these patients is due to changes of SACT or due to spontaneous variations of sinus node automaticity. The measurement of the first spontaneous interval (A3-A4) after the postextrasystolic pause revealed a prolongation of 30 ms (mean value) in comparison to the basic cycle length (A1-A1) after resetting the sinus node. If the stimulus was elicited late in diastole without premature depolarisation of the pacemaker cells, no significant difference between A3-A4 and A1-A1 intervals could be found. These results indicate that sinus node automaticity may be influenced by the premature stimulus. Therefore, the calculation of SACT is burdened by unresolved methodological problems.

Arrhythmias, Cardiac↗
PubMed1991

Prolonged atrial activity due to delayed conduction in the atrium of patients with paroxysmal atrial fibrillation.

We investigated the relationship between the duration of electrical atrial activity and intra-atrial conduction time to determine whether the prolonged atrial activity was due to delayed conduction in the human atrium. The study included 15 patients with paroxysmal atrial fibrillation (PAF) and 15 control patients. The duration of atrial electrical activity was measured by selecting a minimum electrographic amplitude of 50 microV. In patients with PAF, the duration of atrial activity was prolonged in proportion to the delay of interatrial conduction time from the high right atrium to the coronary sinus as the coupling interval of premature extrastimuli was decreased. Both the fragmented atrial activity zone and the interatrial conduction delay zone were wider in patients with PAF than in control patients. It is concluded that assessment of the duration of atrial activity with a minimum amplitude of 50 microV is useful in evaluating human atrial vulnerability since it reflects the atrial conduction delay in patients with PAF.

Adolescent↗
PubMed2006

"Sensing alternans" in a patient with a newly implanted pacemaker.

This report describes the case of an 80-year-old man with a history of coronary artery disease who presented with acute pericarditis secondary to pacemaker lead perforation of the ventricular wall 2 days after undergoing dual lead pacemaker implantation. The electrocardiogram revealed sinus rhythm with an intra-atrial conduction delay and intermittent failure of atrial sensing as evidenced by alternating atrial spikes in every other P wave. The noted pericardial effusion and the likely shifting of the atrial lead with each alternate beat caused the "sensing alternans" that was seen on the admission electrocardiogram.

Aged↗
PubMed1996

Efficacy and safety of long-term oral flecainide acetate in patients with responsive supraventricular tachycardia.

In 102 patients with inducible supraventricular tachycardia (SVT), 56 women and 46 men aged 20-86 (mean, 52) years, underwent electrophysiologic study. SVTs observed at electrophysiologic study were atrial flutter or atrial fibrillation (32%), the "slow-fast" form of atrioventricular (AV) nodal reentrant tachycardia (45%), orthodromic AV reentrant tachycardia (25%), and atrial tachycardia (9%). More than 1 SVT occurred in some patients. Spontaneous symptomatic SVT frequency prior to oral flecainide varied from 3/day to 1/3 months (mean, 3/month). At electrophysiologic study and during SVT, intravenous flecainide, 2 mg/kg body weight, was given at an infusion rate of 10 mg/min up to a maximum dose of 150 mg. Patients were commenced on oral flecainide if SVT termination occurred during intravenous flecainide administration and if reinitiation was not possible after the total dose of flecainide had been given. In patients with AV nodal reentrant tachycardia and AV reentrant tachycardia further criteria for commencing oral flecainide were SVT termination by ventricular-atrial conduction block and persistent ventricular-atrial block after intravenous flecainide administration. Initial oral flecainide dosage was determined by assessing ability to reinitiate SVT after 50 mg, 100 mg, and the total dose of intravenous flecainide had been given. Eighty-nine patients (87%) remained free of symptomatic SVT over a mean follow-up period of 3.9 years (range, 3 months to 6.5 years). Two thirds were still taking the original dosage of flecainide and the rest were SVT-free on a higher dosage. Oral dosages ranged from 50 to 300 mg/day (median dosage, 100 mg twice daily) Nine patients experienced minor side effects, including, lethargy, dizziness, headache, and blurred vision. There were no deaths and no reports of major proarrhythmic events or other major adverse effects.

Administration, Oral↗
PubMed1977

Bi-morphic atrial flutter.

A case of atrial flutter whose classic "saw-tooth" morphology, resistant to full doses of digoxin and quinidine, was changed to an unusual form by low energy direct current shock is presented. The atrial and ventricular rates remained identical in spite of the different F wave pattern before and after attempted cardioversions. 0.5 mg digoxin was given after cardioversion failed and the patient reverted to normal sinus rhythm. This case strengthens the theory of rapidly discharging atrial focus as a mechanism of atrial flutter and the case for a change in intra-atrial conductions as cause for change in atrial electrograms.

Adult↗
PubMed1986

Pseudo-atrial dissociation: a respiratory artifact.

Atrial dissociation is an electrocardiographic phenomenon characterized by the occurrence of two separate atrial rhythms. A patient is presented, showing electrocardiographic signs suggestive for atrial dissociation. The dissociated, non-conducted, atrial rhythm showing micro-oscillations after its P wave, is shown to be a respiratory artifact. It is concluded that the micro-oscillations seen on the surface electrocardiogram after a dissociated P wave are probably diagnostic for pseudo-atrial dissociation.

Aged↗
PubMed1993

Radiofrequency ablation therapy in three patients with paroxysmal atrial tachycardia.

Radiofrequency ablation therapy was performed in three patients with paroxysmal atrial tachycardia. There were two females and one male, aged 80, 63, and 75 years, respectively. All three patients had induction of sustained atrial tachycardia. The tachycardia could be terminated by overdrive atrial pacing or atrial premature stimulation; it could also be terminated by intravenous bolus of adenosine triphosphate. In all three patients, there was no fragmented atrial electrograms recorded within the right atrium, and there was no ventriculo-atrial conduction during ventricular pacing. The earliest atrial activation during tachycardia in these three patients was registered, respectively, at a site slightly posterior and inferior to the His-bundle recording site, at the anterior-superior border of Koch's triangle slightly posterior to the His-bundle recording site, and at the mid-lateral aspect of the right atrium over the crista terminalis at the junction of right atrial appendage and sinus venarum. Radiofrequency current was delivered to the site of the earliest atrial activation during tachycardia through a 4-mm tip electrode catheter. It resulted in termination of tachycardia and ablation of the tachycardia focus. Follow-up observation over a period of 16, 15, and 4 months, respectively, in these three patients showed no recurrence of tachycardia. A repeat electrophysiological study was performed 52 and 63 days after ablation in two patients and revealed no induction of atrial tachycardia.

Aged↗
PubMed2006

[Clinical evolution of patients following investigation of atrial vulnerability after a first cerebral ischaemic accident].

Atrial vulnerability reflects the ability of the atrium to fibrillate. ISAV (Ischemic stroke and atrial vulnerability) is a French epidemiological registry whose main goal is to assess the evolution modalities of patients in whom an electrophysiological study of the atrium has been performed. A group of 269 patients with a history of non elucidated ischemic stroke and an electrophysiological study of the atrium performed in a mean delay of 3 months after the stroke has been included. Their mean age at the time of the stroke was 55 +/- 15.8 years. The electrophysiological study has measured the effective refractory period of the atrium, the locoregional right intra-atrial conduction time, the index of latent atrial vulnerability and assessed the inductibility. The mean delay between the date of the stroke and the date of the last news was 4.4 +/- 2.8 years. We observed 12 deaths and 11 patients presented during the follow up a spontaneous atrial arrhythmia and 17 a recurrence of stroke. If we consider the occurrence of the 28 combined events (atrial arrhythmia and/or stroke), it is not correlated with the presence of an atrial septal defect nor with the existence of an atrial vulnerability. On the contrary this occurrence is correlated with tobacco consumption and/or arterial hypertension; 82% of patients have these risk factors versus 54% of patients without events (p = 0.004). This association is not significant in patients younger than 55 years.

Adult↗
PubMed1978

[Cardiac pacing in sinus node disease (author's transl)].

In sinus node disease, cardiac pacing is used as a diagnostic and therapeutic tool. The assessment of sinus node recovery time by means of rapid atrial pacing and sino-atrial conduction time by means of premature atrial stimulation, are the methods usually utilized in the diagnosis of sino-atrial dysfunctions. Theoretical and practical limitations however induce to careful evaluation of the results. Heart pacing is also useful for the treatment of sino-atrial dysfunctions. However, criteria for pacemaker implantation in these conditions are still lacking and the type of pacemaker indicated is not defined yet. At present, the accurate clinical investigation of the patient still remains the best guide to therapeutical approach.

Cardiac Pacing, Artificial↗
PubMed1987

Comparative study of atrial fibrillation and AV conduction in mammals.

Atrial fibrillation is one of the most common cardiac arrhythmias in humans. It also occurs quite frequently in dogs and horses. Comparative study of this arrhythmia may contribute to better understanding of the pathophysiological mechanisms involved. In this study, we present a quantitative analysis of atrial fibrillation in humans, dogs, horses, and in a kangaroo, making use of histograms and serial autocorrelograms of the ventricular rhythm with and without digitalis medication. Increase in the size of the animal and thus in the size of the heart is accompanied by a decrease in ventricular rate. The ventricular rhythm was random in the dog, kangaroo, and man, but periodicity was present in the horse. Digitalis decreased the ventricular rate in all species studied and enforced the periodicity in the horse. The differences in the atrial excitation process, atrioventricular (AV) conduction, and ventricular behavior between the four species studied are small when compared with the differences in their heart size. We conclude that in evolution, as far as the heart is concerned, cell size and morphology probably prevail over cell-function.

Animals↗
PubMed1977

[The relation between the electrophysiological parameters of the right atrium and the AV-node conduction (author's transl)].

40 patients were examined with the extrastimulus method at 3 different driving rates (80, 100 and 120/min). It was found that the atrial conduction velocity during the relative refractory period sometimes explains a paradoxical conduction of a premature atrial beat. The AV-node conduction is mainly determined by the correlation between the functional refractory period of the right atrium (FRPRA) and the effective retractory period of the AV-node (ERPAVN). With increasing driving rate the FRPRA shortened while ERPAVN lengthened. This explains why in this study the number of patients in which the ERPAVN could be reached progressively increased from 23 at a driving rate of 80/min to 31 and 33, respectively, at the driving rates of 100 and 120/min.

Adolescent↗