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PubMed1990

[Right ventricular dysplasia].

Right ventricular dysplasia (RVD) is characterized by partial or total replacement of part of the right ventricular musculature by fatty and fibrous tissue. In its typical form it presents with ventricular tachycardia, usually in the fourth decade of life. 6 men and 2 women (mean age 55.6 years), referred for evaluation of arrhythmias or other cardiac symptoms, were diagnosed as having RVD on echocardiography after other causes of right ventricular enlargement were excluded. The mean age was 55.6 years, older than originally reported. 5 presented with supraventricular arrhythmias, including atrial flutter, atrial fibrillation, supraventricular tachycardia and sick-sinus syndrome. Only 2 had ventricular tachycardia; in 1 patient no arrhythmia was found. We conclude that RVD includes a wide spectrum of arrhythmias, of which ventricular tachycardia is probably not the most common. The incidence of RVD in the older population may be greater than originally reported, and may include a slowly developing form of the disease. In some cases RVD may be the pathophysiological basis of lone atrial fibrillation and sick-sinus syndrome.

Adult↗
PubMed1986

[Experience with VVI, QT time and activity-controlled pacemaker systems in patients with tranvenous ablation of atrioventricular conduction].

In 36 patients with atrial flutter, atrial fibrillation or supraventricular tachycardia, refractory to medical treatment, who underwent interruption of atrioventricular conduction by means of an electrode-catheter, i.e. His bundle ablation, various pacemakers were studied. In 22 patients (group I) a heart rate programmable VVI-pacemaker was implanted, in 7 patients (group II) an activity-mode pacemaker (Activitrax 8400, Fa. Medtronic) and in 7 patients (group III) a QT-mode pacemaker (Quintech 911, Fa. Vitatron). To study physical work capacity, exercise testing was performed using a bicycle ergometer in group I and group III and a treadmill in group II. Sixteen patients with VVI-mode pacing (72.7%) complained of shortness of breath during exercise in normal daily life, in comparison to only 2 patients in group II (28.6%) and 3 patients in group III (42.9%). The exercise test revealed a normal physical work capacity in only 3 out of 22 patients (13.6%) with a VVI-pacemaker, but a normal physical work capacity in all patients with activity-mode or QT-mode pacing. Heart rate during stress test in patients with an Activitrax-pacemaker increased more rapidly than in patients with a Quintech-pacemaker and also dropped more quickly in the Activitrax-group than in the Quintech-group after cessation of the stress test. It is important to note that pacemaker reprogramming was necessary in 1 out of 7 patients (14.3%) with activity-mode pacing and in 4 out of 7 patients (57.1%) with QT-mode pacing.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Electrophysiological profile of bepridil, a new anti-anginal drug with calcium blocking properties.

The electrophysiological effects of intravenously administered bepridil, a new anti-anginal drug with slow calcium current blocking properties, were studied in 20 patients undergoing an endocavitary cardiac exploration for various reasons. Classical techniques of programmed electrical stimulation were used. Bepridil markedly increased the refractory period of the atrium, atrioventricular node and the AH-interval. The effects on HR and ventricular refractory period were minimal, and sinus rate decreased slightly. A pronounced reduction in the heart rate at which the Wenckebach phenomenon was obtained in the anterograde direction (16%) and particularly in the retrograde direction (26%) was observed. During this study the drug appeared beneficial in suppressing atrial flutter, atrial extrasystoles, and ventricular extrasystoles. In two patients with intranodal reciprocal rhythm, the injection of bepridil terminated the tachycardia which could not be reinitiated later. No side-effects occurred and it appears that bundle branch block and prolonged HV interval are not contraindications to the use of bepridil.

Adult↗
PubMed1978

Endocardial and His bundle electrocardiograms.

Endocardial electrocardiograms permit the analysis of auricular depolarization and contribute to the study of ventricular activation. Direct recording of auriculograms from the right atrium and indirect recording of the left auriculograms through the coronary sinus and pulmonary artery, show the different auricular activation pathways in common atrial flutter, atrial tachycardia and in case of retrograde atrial depolarization (via the AV node, septal or parietal accessory pathway). His bundle electrograms obtained via the femoral vein or, less easy, via the brachial vein, has introduced an essential mark in the analysis of intracardiac activation enabling us to precisely locate lesions of the AV conduction system, making easier differential diagnosis between aberrant ventricular conduction and ventricular ectopic rhythms and contributing to the study of ventricular preexcitation. Endocavitary stimulation at increasing rate and by the single extrastimulus technique is the complement of intracardiac electrocardiography in evaluating sinus node function, conduction times and refractory periods at different levels, electrophysiological properties of accessory pathways and studies of the antiarrhythmic drugs. Programmed stimulation allows the recognition of reentry as the mechanism of many tachyarrhythmias. The recording of monophasic action potential by the suction--electrode technique is another step in the intracavitary electrophysiological investigation.

Action Potentials↗
PubMed1980

[Hemodynamic and electrophysiologic effects of the new calcium antagonist Ro 11-1781 (author's transl)].

In a 3-part study the new calcium-antagonist Ro 11-1781 was investigated in respect to hemodynamic, electrophysiologic and antiarrhythmic effects. In the first part of the investigation, systolic time intervals were determined as an indicator of left ventricular performance in 10 patients without cardiac disease before and 5 min after i.v. injection of Ro 11-1781 (1 mg/kg/body weight). At the same time blood pressure was measured. There was a significant decrease in systolic and diastolic blood pressure (p < 0.01). Due to the resulting activation of the sympathetic nervous system by baroreflex, heart rate increased by 7 bpm (p < 0.01), there was a shortening of the pre-ejection period PEPc by 15 ms (p < 0.01), whereas left ventricular ejection time LVETc was not changed significantly. The ratio PEPc/LVETc decreased significantly (p < 0.01), reflecting the increase of left ventricular contractility, which results from the activation of the sympathetic nervous system. The PQ interval was increased (16 ms, p less than 0.01), an atrioventricular block however was not seen. In the second part of the investigation, sinus node function was studied in 8 patients by His-bundle electrography and programmed stimulation of the right atrium. There was no significant change in sinus-node recovery time, sinu-atrial conduction time, sinus-node rate and atrial conduction time in response to Ro 11-1781. However, in 2 patients with sinus-bradyarrhythmia a second-degree sinu-atrial block was provoked by the calcium-antagonist. The drug was shown to have a negative dromotrope effect to the AV node, reflected by an increase of the PQ interval (p < 0.01), AH interval (p < 0.01) and a decrease (p < 0.01) of the maximal 1:1 conduction of the AV node, whereas the HV interval was not changed significantly. The antiarrhythmic effects of Ro 11-1781 were studied in 13 patients with atrial flutter, atrial fibrillation or paroxysmal supraventricular tachycardia: In 10 patients the injection of the calcium-antagonist produced a marked decrease in ventricular rate for a short time reflecting a neagative dromotrope effect in the AV node. In 5 patients conversion to sinus rhythm was observed.

Adult↗
PubMedDate not supplied

[The bradycardia-tachycardia syndrome].

Disorders of the heart rhythm which consist basically of sinus bradicardia or sinus arrest correspond to a syndrome which has been named the sick sinus syndrome. Within the framework of this syndrome, there is a subgroup of alternating atrial bradycardia with episodes of atrial tachyarrhythmia. Generally known as the bradycardia-tachycardia syndrome, this subgroup is both electrophysiologically interesting and therapeutically challenging. This report is concerned with the experience obtained at the emergency ward and coronary care unit of the Instituto Nacional de Cardiología de México on the diagnosis and management of 8 patients with this syndrome. Various underlying heart conditions were present with predominance of ischemic heart disease. The clinical picture was dependent upon the hypoperfusion of vital organs secondary to the cardial arrhythmia. The most common symptoms were derived from cerebral circulatory deficit and coronary insufficiency. Half of the patients had moderate cardiac failure. All patients had spontaneous and transient loss of sinus function which lasted more than 2,000 msec. in seven. The bradycardia had a rate below 50 beats per minute in all cases except one. The tachyarrhythmias observed were atrial flutter, atrial fibrillation and paroxysmal supraventricular tachycardia. Three of the patients had more than one of these these tachyarrhythmias during the period of study. A discussion is made on the diagnosis of this syndrome by means of atrial pacing and interventions which modify either vagal or sympathetic tone. Considerations are also made on the frequent associated abnormality of the A-V functional tissues. Emphasis is placed on the problems encountered in the management of these patients. It is concluded that, in most cases, a satisfactory result may be obtained by the implantation of a permanent demand pacemaker associated to the administration of antiarrhythmic drugs.

Adult↗
PubMed1997

[Evaluation of hyperkinetic cardiac arrhythmia in chronic obstructive bronchopneumopathy].

Patients with chronic obstructive pulmonary disease (COPD), especially during acute exacerbations of their disease, show a greater incidence of cardiac arrhythmias than healthy subjects of the same age. The type of arrhythmias found may be supraventricular (premature atrial beats, paroxysmal supraventricular tachycardia, multifocal atrial tachycardia, atrial flutter, atrial fibrillation) or ventricular (premature ventricular beats, sustained ventricular tachycardia, torsades de pointes, ventricular fibrillation) that may lead to sudden cardiac death. The pathogenesis of arrhythmias is complex and many factors may be involved such as hypoxemia, hypercapnia, respiratory acidosis, metabolic and respiratory alchalosis, hypokalemia, concomitant ischemic heart disease, chronic cor pulmonale, left ventricular diastolic dysfunction. Remarkable attention has been drawn to the possible arrhythmogenic effect of drugs such as theophylline, beta-adrenergic stimulants and digitalis which are commonly used in the therapy of COPD. Both of the main classes of bronchodilators (methylxanthynes and beta-adrenergic agonists), even when used together, apparently do not increase the incidence of dangerous cardiac arrhythmias. However, these drugs should be used with caution in the elderly, in patients with preexisting cardiac arrhythmias, with heart disease or with reduced hepatic function. In these cases Holter monitoring, repeated measurements of plasma drugs concentration and prompt hospitalization of high risk patients in Intensive Care Unit may be needed.

Adrenergic beta-Agonists↗
PubMed2002

Electrical cardioversion for atrial fibrillation and flutter.

BACKGROUND: Atrial fibrillation increases the risk of stroke, increases the risk of cognitive impairment, and adversely affects cardiovascular haemodynamics. Electrical cardioversion for atrial fibrillation has been in use since the 1960s; the rationale is that restoration of sinus rhythm improves cardiovascular haemodynamics, reduces the risk of stroke, and obviates the need for long-term anticoagulation. OBJECTIVES: To assess the effects of electrical cardioversion of atrial fibrillation or atrial flutter on the annual risk of thromboembolic events, strokes and mortality (primary outcomes measures), the rate of cognitive decline, quality of life, the use of anticoagulants and the risk of re-hospitalisation (secondary outcome measures) in adults (>18 years) with acute, paroxysmal or sustained atrial fibrillation or atrial flutter, of any duration and any aetiology. SEARCH STRATEGY: One reviewer searched the Cochrane Controlled Clinical Trials Register (2000 Issue 4), MEDLINE (1966 to December 2000), EMBASE (1980 to December 2000), CINAHL (1982 to November 2000) and proceedings of the American College of Cardiology (published in the Journal of the American College of Cardiology 1983 to 2000). Reference lists of articles were searched. Personal contact was made with experts in the field. A second reviewer handsearched proceedings of the British Cardiac Society (published in British Heart Journal (1980 to 1995) and in Heart (1995 to May 2001); proceedings of the European Congress of Cardiology and meetings of the Joint Working Groups of the European Society of Cardiology (published in European Heart Journal 1983-2000); scientific sessions of the American Heart Association (published in Circulation 1990-2000). SELECTION CRITERIA: Randomised controlled trial or controlled clinical trials of electrical cardioversion plus 'usual care' versus 'usual care' only, where 'usual care' included any combination of the following: anticoagulants, antiplatelet drugs and drugs for 'rate control', in adults (>18 years) with acute, paroxysmal or sustained atrial fibrillation or atrial flutter, of any duration and any aetiology. DATA COLLECTION AND ANALYSIS: It was planned to extract study data onto data extraction forms. The planned analysis was by the statistical package in RevMan. MAIN RESULTS: No completed randomised trials or controlled clinical trials of electrical cardioversion were found. Two ongoing trials were identified. REVIEWER'S CONCLUSIONS: There were no data from completed randomised controlled trials or controlled clinical trials to either support or refute the use of electrical cardioversion for atrial fibrillation. Randomised trials of electrical cardioversion are required.

Adult↗
PubMed2001

Studies on the prevalence of complicated atrial arrhythmias, flutter, and fibrillation in patients with reciprocating supraventricular tachycardia before and after successful catheter ablation.

Atrial flutter and AF are complications in approximately 30% of cases of paroxysmal supraventricular tachycardia (PSVT)-indicated catheter ablation, and it is of interest to determine if therapeutic modification for PSVT would eliminate combined atrial tachyarrhythmia like atrial flutter and AF. The aim of this study was to determine the incidence and the risk of atrial tachyarrhythmias after catheter ablation of PSVT. A total of 152 patients (age range 12-74, mean 41 +/- 17 years) with accessory pathway (n = 106) and/or dual atrioventricular nodal conduction (n = 46) were enrolled in a 2-year follow-up program after successful catheter ablation. Possible risks on clinical background (age, sex, PSVT duration, hemodynamic instability during attacks), premature atrial contraction (PACs) on Holter monitoring, echocardiographic left atrial size, and electrophysiological property (insertion site, conduction type, effective refractory period) were evaluated. Atrial flutter and AF were complications in 53 (35%) of the subjects, who were elderly and had a longer PSVT history with a larger left atrial dimension and frequent PACs; however, the electrophysiological properties were similar. After a 2-year follow-up period 36 (24%) of the patients still exhibited PAC runs, including 13 (9%) with atrial flutter and AF, each one of whom were complicated with nonlethal cerebral thromboembolism and congestive heart failure. Multiplelogistic-regression analysis revealed that advanced age (> or = 41 years, P = 0.0152) and frequent PACs (> or = 1% of total daily QRS counts, P = 0.0426) on Holter monitoring are the risk factors of PAC runs and/or atrial flutter and AF. In conclusion, successful ablation for PSVT is thought to be beneficial for preventing atrial flutter and AF. However, careful follow-up to monitor for the recurrence and atrial flutter and AF related complications, especially in patients of solitary atrial flutter and AF without reciprocating tachycardia and with frequent PAC.

Adolescent↗
PubMed1994

Radiofrequency catheter ablation of atrial arrhythmias. Results and mechanisms.

BACKGROUND: Radio frequency catheter ablation is accepted therapy for patients with paroxysmal supraventricular tachycardia and has a low rate of complications. For patients with atrial arrhythmias, catheter ablation of the His bundle has been an option when drugs fail or produce untoward side effects. Although preventing rapid ventricular response, this procedure requires a permanent pacemaker and does not restore the atrium to normal rhythm. Therefore, we evaluated the safety and efficacy of radiofrequency ablation directed at the atrial substrate. METHODS AND RESULTS: Thirty-seven patients with 42 atrial arrhythmias (mean +/- SD age, 41 +/- 24 years) who had failed a median of three drugs were enrolled. Diagnoses were automatic atrial tachycardia in 12, atypical atrial flutter in 1, typical atrial flutter in 18, reentrant atrial tachycardia in 8, and sinus node reentry in 3 patients. Sites for atrial flutter ablation were based on anatomic barriers in the floor of the right atrium. For automatic atrial tachycardia, the site of earliest activation before the P wave was sought. All with reentrant atrial tachycardia had previous surgery for congenital heart disease and reentry around a surgical scar, anatomic defect, or atriotomy incision and our goal was to identify a site of early activation in a zone of slow conduction. At target sites, 20 to 50 W of radiofrequency energy was delivered during tachycardia between the 4- or 5-mm catheter tip and a skin patch, except in 4 patients with atrial flutter, in whom a catheter with a 10-mm thermistor-embedded tip was used. Procedure end point was inability to reinduce tachycardia. Acute success was achieved in 11 of 12 (92%) with automatic atrial tachycardia, 17 of 18 (94%) with typical atrial flutter, 7 of 8 (88%) with reentrant atrial tachycardia, and 3 of 3 (100%) with sinus node reentry but not in the patient with atypical atrial flutter. For tachycardia involving reentry (reentrant atrial tachycardia and atrial flutter), successful ablation required severing an isthmus of slow conduction. For those with atrial flutter, this was between the tricuspid annulus and the coronary sinus os (10) or posterior (4) or posterolateral (3) between the inferior vena cava (2) or an atriotomy scar (1) and the tricuspid annulus. Deep venous thrombosis occurred in 1 patient. At mean follow-up of 290 +/- 40 days, the ablated arrhythmia recurred in 1 (9%) with automatic atrial tachycardia, 5 (29%) with atrial flutter, and 1 (14%) with reentrant atrial tachycardia, all of whom had successful repeat ablation. Previously undetected arrhythmias occurred in 2 patients who are either asymptomatic or controlled with medication. CONCLUSIONS: Ablation of automatic and reentrant atrial tachycardia and atrial flutter had a high success rate and caused no complications from energy application. Repeat procedures may be required for long-term success, especially in patients with atrial flutter. The mechanism by which ablation is successful is similar for atrial flutter and other forms of atrial reentry and involves severing a critical isthmus of slow conduction bounded by anatomic or structural obstacles. Automatic arrhythmias are abolished by directing lesions at the focus of abnormal impulse formation.

Adult↗
PubMed1988

Intravenous flecainide acetate for supraventricular tachycardias.

Flecainide acetate, 2 mg/kg body weight, given intravenously at 10 mg/min was administered to 128 (74 male and 54 female) patients whose ages ranged from 11 to 86 years (mean 44). All patients had supraventricular tachycardias (SVT) that developed spontaneously or were induced during electrophysiologic study. There were 26 patients with atrial flutter, 34 with atrial fibrillation, 7 with ectopic atrial tachycardia, 41 with atrioventricular (AV) reentrant tachycardia and 40 with AV nodal reentrant tachycardia. Twenty patients had more than 1 variety of SVT. Flecainide was administered during SVT to 9 patients with atrial flutter, 11 with atrial fibrillation, 7 with atrial tachycardia, 38 with AV reentrant tachycardia and 34 with AV nodal reentrant tachycardia. In the remaining 31 patients with inducible SVT at electrophysiologic study, flecainide was administered during sinus rhythm. Reinitiation of SVT was attempted in these patients after completion of flecainide administration. Flecainide successfully terminated atrial flutter in 2 patients (22%), atrial fibrillation in 9 (82%), atrial tachycardia in 5 (71%), AV reentrant tachycardia in 32 (84%) and AV nodal reentrant tachycardia in 30 (88%). Reinitiation of SVT was possible in 10 of 26 patients with atrial flutter (38%), 5 of 34 with atrial fibrillation (15%), 3 of 7 with atrial tachycardia (43%), 14 of 41 with AV reentrant tachycardia (34%) and 11 of 40 with AV nodal reentrant tachycardia (27%). In patients with AV reentrant tachycardia and AV nodal reentrant tachycardia, reinitiation occurred when retrograde anomalous pathway refractoriness was not significantly prolonged by intravenous flecainide.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Internal transvenous low energy cardioversion for the treatment of cardiac arrhythmias.

Low energy endocardial cardioversion was attempted in 23 patients with 30 arrhythmias, of whom only four were receiving additional drug treatment. Four had atrial flutter, five atrial fibrillation, three intra-atrioventricular nodal tachycardia, two atrioventricular re-entrant tachycardia, 13 ventricular tachycardia, and three ventricular fibrillation. A pacing lead with special large surface area electrodes--the active electrode positioned either in the right atrium or in the right ventricular apex and the indifferent electrode in the right atrium, superior vena cava, or inferior vena cava--was used together with a low energy defibrillator. A total of 114 shocks was delivered, 26 of which were atrial. One episode of atrial flutter was terminated, but atrial fibrillation and atrioventricular nodal tachycardia were not terminated in any of the patients. Both patients with atrioventricular tachycardia were successfully treated, as were eight of the patients with ventricular tachycardia. Atrial fibrillation was produced in three patients and non-sustained ventricular tachycardia in one, ventricular tachycardia was accelerated in two, and ventricular fibrillation induced in five. Fourteen patients experienced severe discomfort and seven mild or moderate discomfort, and only one found the procedure painless. One patient was anaesthetised throughout the procedure. Low energy endocardial cardioversion is not universally successful even at the highest energies tolerable, and with the present electrode and pulse waveforms some patients may suffer considerable discomfort.

Adult↗
PubMed2005

Pharmacological cardioversion for atrial fibrillation and flutter.

BACKGROUND: Atrial fibrillation is the commonest cardiac dysrhythmia. It is associated with significant morbidity and mortality. There are two approaches to the management of atrial fibrillation: controlling the ventricular rate or converting to sinus rhythm in the expectation that this would abolish its adverse effects. OBJECTIVES: To assess the effects of pharmacological cardioversion of atrial fibrillation in adults on the annual risk of stroke, peripheral embolism, and mortality. SEARCH STRATEGY: We searched the Cochrane Controlled Trials Register (Issue 3, 2002), MEDLINE (2000 to 2002), EMBASE (1998 to 2002), CINAHL (1982 to 2002), Web of Science (1981 to 2002). We hand searched the following journals: Circulation (1997 to 2002), Heart (1997 to 2002), European Heart Journal (1997-2002), Journal of the American College of Cardiology (1997-2002) and selected abstracts published on the web site of the North American Society of Pacing and Electrophysiology (2001, 2002). SELECTION CRITERIA: Randomised controlled trials or controlled clinical trials of pharmacological cardioversion versus rate control in adults (>18 years) with acute, paroxysmal or sustained atrial fibrillation or atrial flutter, of any duration and of any aetiology. DATA COLLECTION AND ANALYSIS: One reviewer applied the inclusion criteria and extracted the data. Trial quality was assessed and the data were entered into RevMan. MAIN RESULTS: We identified two completed studies AFFIRM (n=4060) and PIAF (n=252). We found no difference in mortality between rhythm control and rate control relative risk 1.14 (95% confidence interval 1.00 to 1.31). Both studies show significantly higher rates of hospitalisation and adverse events in the rhythm control group and no difference in quality of life between the two treatment groups. In AFFIRM there was a similar incidence of ischaemic stroke, bleeding and systemic embolism in the two groups. Certain malignant dysrhythmias were significantly more likely to occur in the rhythm control group. There were similar scores of cognitive assessment. In PIAF, cardioverted patients enjoyed an improved exercise tolerance but there was no overall benefit in terms of symptom control or quality of life. AUTHORS' CONCLUSIONS: There is no evidence that pharmacological cardioversion of atrial fibrillation to sinus rhythm is superior to rate control. Rhythm control is associated with more adverse effects and increased hospitalisation. It does not reduce the risk of stroke. The conclusions cannot be generalised to all people with atrial fibrillation. Most of the patients included in these studies were relatively older (>60 years) with significant cardiovascular risk factors.

Adult↗
PubMed2001

NASPE Plenary Lecture 2001. Catheter ablation: a personal perspective.

Catheter ablation for control of cardiac arrhythmias was introduced 20 years ago. Since then, this technique has been applied successfully to virtually all cardiac rhythm disturbances. In this essay, some of the newer applications of ablative techniques for patients with AV nodal reentrant tachycardia, atrial flutter, and atrial fibrillation are emphasized. "AV nodal reentrant tachycardia" may involve a nodofascicular tract. A new classification of atrial flutter is proposed and various causes of atrial fibrillation are discussed.

Animals↗
PubMed1981

Coexistence of sick sinus rhythm and atrial flutter-fibrillation.

A 58-year-old man with hypertensive cardiovascular disease and atrial flutter underwent electrophysiologic studies, including multiple intra-atrial recordings and atrial stimulation. Although the surface ECG suggested the presence of atrial flutter, intra-atrial recordings demonstrated the presence of (1) sinus-like rhythm localized to an area of approximately 5 mm in and around the region of the sinus node, which was protected by entrance block; (2) flutter and/or fibrillation of the remaining parts of the right atrium; (3) fibrillation of the left atrium; and (4) transient degeneration of flutter into fibrillation at right atrial sites, with predominant flutter activity. Although a major part of the right atrium was in flutter and/or fibrillation, we could assess sinus node function by overdrive stimulation of the area of sinus node-activity. Sinus node function studied revealed an underlying sick sinus syndrome.

Atrial Fibrillation↗
PubMed1997

Failure of automatic mode switching: recognition and management.

Dual chamber pacing is desirable to optimize AV synchrony and to potentially decrease the incidence of supraventricular tachyarrhythmias. Patients with alternating periods of both supraventricular tachyarrhythmias and bradycardia pose a difficult challenge when standard dual chamber pacemakers are implanted. The automatic mode switching mode algorithm was introduced to prevent tracking of paroxysmal supraventricular tachyarrhythmias and avoid the adverse hemodynamic and symptomatic consequences of a rapid ventricular response. In some cases, failure to mode switch may take place when the atrial signal during tachycardia is of insufficient amplitude to be sensed. Failure to mode switch may also occur when the atrial signal periodically occurs in the atrial blanking period(s). In this article, we describe failure to mode switch in seven patients with paroxysmal supraventricular tachyarrhythmias after a Telectronics Meta DDDR 1254 device was implanted. Each patient had paroxysmal atrial flutter and/or atrial fibrillation and presented with either repetitive episodes of oscillation between atrial tracking and mode switching to a nonatrial tracking pacing mode or complete failure to mode switch. Six of seven patients were taking antiarrhythmic drugs that resulted in slowing of the atrial cycle length. Pacemaker reprogramming was required in each case to restore reliable mode switching during subsequent recurrences of the atrial tachyarrhythmias. We conclude that careful pacemaker programming of patients with paroxysmal atrial flutter and the Telectronics Meta DDDR 1254 is necessary when patients are taking an antiarrhythmic drug that slows atrial cycle length.

Aged↗
PubMed1996

[Electrocardiographic diagnosis and acute treatment of atrial fibrillation and flutter episodes].

Both atrial flutter and fibrillation are common arrhythmias in the clinical setting. Although we have been aware of them for decades, little has been known until recently about their triggering or maintenance mechanisms. The diagnosis of these arrhythmias lies largely in the electrocardiogram, which shows characteristic features of atrial electrical activity, leading to a correct diagnosis. Usually, some maneuvers such as adenosine infusion, carotidus sinus massage, etc., are required, in order to unmask the atrial activity, that are often obscured by the QRS complex or T wave. Several therapeutic options can be attempted for the acute termination of both atrial flutter and fibrillation episodes. The choice of one or another depends on some extent, on the clinical status of the patient during the arrhythmia, the presence of structural heart disease and the preceding arrhythmic history. Antiarrhythmic drugs are quite efficacious in the acute conversion of atrial fibrillation, but such an effect is not expected in atrial flutter. Drugs that depress AV nodal conduction can be used in both instances, as a therapeutic end-point or as a previous measure to the arrhythmia conversion. Direct current cardioversion is a good and efficacious option for both arrhythmias, however sedation is mandatory which, may be a contraindication in some patients. Rapid atrial pacing is an elegant and reliable method for the acute termination of atrial flutter of the common type, although a transvenous catheter insertion is needed.

Atrial Fibrillation↗