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PubMed1998

Impact of structural heart disease on the selection of class III antiarrhythmics for the prevention of atrial fibrillation and flutter.

Antiarrhythmic agents may be beneficial or harmful. Among the harmful effects, or risks, is proarrhythmia. One of several factors that underlie proarrhythmic risk is the presence and nature of any underlying structural heart disease at the time of antiarrhythmic drug administration. The structural disease-antiarrhythmic drug interaction has been best studied and clearly delineated for class I antiarrhythmics. This review provides information to suggest that structural disease can enhance proarrhythmic risk with class III drugs as well, although this is least evident with amiodarone. Particularly pertinent are disorders that prolong action potential duration (such as ventricular hypertrophy or chronic dilatation), inhomogeneous dispersion of refractoriness (including conditions with cellular uncoupling), and reduced ventricular fibrillation threshold. These issues must be considered when choosing an antiarrhythmic drug for atrial and for ventricular arrhythmias and when selecting the dosing and monitoring protocol to be used.

Anti-Arrhythmia Agents↗
PubMed1994

Complex atrial tachycardias and respiratory syncytial virus infections in infants.

Respiratory syncytial virus (RSV), a common cause of respiratory infections in children, has only rarely been associated with acquired heart disease. We reviewed hospital charts, rhythm strips, and electrocardiograms of 8 infants with abnormal supraventricular tachycardia (SVT), > 250 beats/min, associated with acute RSV infections. Cultures of nasopharyngeal specimens from six of eight infants grew RSV. Two infants with negative viral culture results had symptoms typical of an RSV infection during a documented RSV epidemic. Two infants had congenital heart defects. Seven of the eight infants had an ectopic atrial tachycardia, chaotic atrial tachycardia, or atrial flutter, and five of eight had episodes of nonsustained wide-complex SVT. One patient was initially treated with intravenously administered lidocaine for an incorrect diagnosis of ventricular tachycardia. SVT was unrelated to either beta-agonist therapy or hypoxic episodes. SVT did not recur after discharge in any infant with a structurally normal heart. Both patients with structural heart disease had recurrences of SVT. We conclude that RSV infections in infants may be associated with unusual atrial tachycardias and that the diagnosis may be complicated by episodes of nonsustained, wide-complex tachycardias. In patients with RSV and structurally normal hearts, chaotic and ectopic atrial tachycardias are self-limited and do not require prolonged drug therapy.

Atrial Flutter↗
PubMed1986

Findings on ambulatory electrocardiographic monitoring in subjects older than 80 years.

Twenty-four-hour electrocardiograms were recorded in 50 subjects (44 women, 6 men) older than 80 years without cardiovascular disease and with normal standard electrocardiographic responses. During waking and sleeping periods, the mean sinus rates were, respectively, 78 +/- 3 and 64 +/- 1 beats/min; heart rate ranged from 43 to 180 beats/min over 24 hours. Supraventricular tachycardia (SVT) was present in 28% of the subjects. Nocturnal sinus arrhythmia was only noted in 12% of the patients; it was accompanied by sinus pauses of 1.8 to 2 seconds, and 1 woman had a transient pattern compatible with atrioventricular dissociation. Supraventricular ectopic contractions (SVECs) were present in all cases. The frequency was less than 1 per hour in 25% and more than 20 per hour in 65%. Serious supraventricular tachyarrhythmias included an episode of ectopic atrial tachycardia (1 subject), a short run of atrial fibrillation (1 subject) and of flutter (1 subject), and several episodes of supraventricular tachycardia (2 subjects), all accompanied by more than 50 SVECs per hour. The number of ventricular premature contractions (VPCs) exceeded 10 per hour in 32% and were multifocal in 18%. There were couplets in 8% and a run of 6 VPCs in 1 subject (2%). In conclusion, sinus pause and atrioventricular block are unusual in people older than 80 years without apparent heart disease. In contrast, frequent SVECs and VPCs are more common. This study stresses the difficulty of evaluating the normality of the electrocardiogram with portable monitoring in the older population.

Aged↗
PubMed1993

[Pulmonary valve endocarditis and atrial fibrillation].

A 61-year-old man became ill with a fever of 39.4 degrees C, decreased exercise tolerance and headache as well as chest pain. Physical examination 3 weeks after the onset of symptoms merely revealed irregular heart rate at 100 beats/min. Erythrocyte sedimentation rate was increased (30/61 mm), as were serum bilirubin, lactate dehydrogenase, alkaline phosphatase, gamma-GT and C-reactive protein. The ECG showed atrial fibrillation with a rapid and irregular ventricular rate, as well as ventricular extrasystoles (Lown type IIIA), there were no abnormal findings on either the chest radiography or transthoracic echocardiography. Antiarrhythmic treatment brought about atrial flutter with 4:1 a-v conduction. Transoesophageal echocardiography now revealed vegetation on the pulmonary valve and microthrombi in the left atrial appendage. Ten days after starting intravenous penicillin G (10 mega units four times daily), gentamycin (60 mg three times daily) and heparin (30,000 units over 24 h) sinus rhythm was restored, the vegetation had got smaller and no thrombi were demonstrated. After 27 days antibiotic treatment was changed to oral penicillin V. After 4 weeks the patient was discharged symptom-free.

Atrial Fibrillation↗
PubMed1984

Cardiac, skeletal, and ocular abnormalities in patients with Marfan's syndrome and in their relatives. Comparison with the cardiac abnormalities in patients with kyphoscoliosis.

Polygraphic (including apexcardiograms and carotid pulse tracings) and M mode echocardiographic examinations were carried out in 34 symptomatic patients with Marfan's syndrome; similar studies were performed in 32 relatives and in 34 young patients with kyphoscoliotic disease. The purpose of these investigations was to determine the association between cardiac and oculoskeletal abnormalities and to identify specific patterns of disease with a poor prognosis. Polygraphic tests showed significant changes in all patients with Marfan's syndrome: 74% showed the apical systolic click and murmur of mitral valve prolapse; 48% had the diastolic murmur of aortic regurgitation; isolated mitral valve prolapse was found in 52%, 26% had isolated aortic regurgitation, and 22% had a combination of the two. Echocardiographic changes were also found in all patients: 79% had aortic root dilatation; 48% fluttering of the anterior mitral leaflet; 79% mitral valve prolapse, mostly pansystolic; 34% both mitral prolapse and aortic root dilatation; and 34% left ventricular dilatation. The severities of the cardiac and oculoskeletal abnormalities were not correlated. The high prevalence of mitral valve prolapse found in these patients, which did not vary with age or sex, was also present in their relatives: mitral prolapse was present in 38% and aortic dilatation, with or without regurgitation, in 14%. Four of the relatives had clearcut Marfan's syndrome, and at least four others a forme fruste. The metacarpal index was abnormal in 41% of the relatives; ocular abnormalities were rare. In kyphoscoliotic patients only an increase in the prevalence of mitral prolapse (18.2% in women, none in men) was found. These findings underline a complex pattern of association between cardiac, ocular, and skeletal abnormalities in patients with Marfan's syndrome and confirm an appreciable inheritability of several of the markers of the disease.

Adolescent↗
PubMedDate not supplied

[The mitral valve chordal system as a cause of innocuous heart murmur].

To specify the role of morphofunctional features of mitral chorda in forming innocent cardiac murmur (ICM), 107 and 20 young men with or without ICM, respectively, were examined clinically and instrumentally at rest, muscular load and hyperventilation. Echocardiography was recorded in one-dimentional, sectoral and Doppler regimens. Fluttering chorda (FC) of the mitral valve (MV) manifesting by hyperkinesia of usually fixed MV chorda, its early systolic dislocation into the left ventricular outflow tract was registered in 34.5% of ICM patients, 11.2% of them had echocardiographic evidence of the chordal shift in the systole into the above tract. In ICM-free subjects the phenomenon FC and the systolic chordal shift were absent (the difference was significant, p < 0.05). The FC phenomenon is attributed to local dysfunction of the papillary muscles and may produce distinct labile nonregurgitation systolic murmur.

Adolescent↗
PubMed2004

[Narrow QRS tachycardia].

Narrow QRS tachycardia are supraventricular tachycardia, atrial tachycardia or junctional tachycardia. The diagnosis is done with the ECG, after identification of atrial activation, eventually after vagal manoeuvres, and transoesophageal recordings. DC Choc, atrial pacing, or antiarrhythmic drugs can do interruption. All atrial tachycardia must be anticoagulated prior regularisation. There is seldom an emergency for regularisation, as drugs can always slow the ventricular rate down. Prevention of relapses uses oral antiarrhythmic drugs, sometimes pacing. Most of these tachycardia can be cured by catheter ablation, essentially flutter and junctional tachycardia.

Electrocardiography↗
PubMed1996

[Epidemiology, risk factors, and pathogeny of atrial fibrillation and atrial flutter].

Atrial fibrillation is a frequent arrhythmia which has a high prevalence after 65 years of age, thus the typical patient's age is about 75. There are two atrial fibrillation predictors: traditional factors of cardiovascular risk (age, male sex, high blood pressure, diabetes), and structural heart disorders (heart failure, valvular heart disease). All preventive measures to reduce atrial fibrillation incidence, must be directed towards these factors. Additionally, left atrial size, ejection fraction and ventricular hypertrophy are echocardiographic predictors. Atrial fibrillation doubles the mortality rate and is related to an annual stroke rate of 4.5%. The stroke risk factors are: age, hypertension, diabetes, previous stroke, congestive heart failure, coronary heart disease, mitral stenosis, prosthetic heart valves and thyrotoxicosis. Left atrial size and ventricular disfunction are echocardiographic stroke risk factors. Each patient's risk can be stratified on the basis of these factors. All of this information is essential to handle the arrhythmia appropriately; this arrhythmia may be more important than has been thought. Atrial flutter is not very frequent and so it is less studied; however it is an arrhythmia with a similar clinical context to atrial fibrillation, although, probably, with a smaller embolic risk.

Atrial Fibrillation↗
PubMed1978

Mechanisms of tachyarrhythmias, past and present.

Several hypotheses, developed in the early years of arrhythmology, and frequently used for the explanation of many types of clinical tachyarrhythmias, are often based on experiments on unusual models, unphysiologic interventions, or, in some instances, on erroneously interpreted histologic findings. However, it can be demonstrated that several of these hypotheses are valid. Focal activity, unidirectional block, extremely slow conduction velocity, differences in conduction velocity in closely adjacent regions, reentry of the excitation wave, circulating excitation waves in small or large regions of the heart and other postulated mechanisms as, for example, entrance and exit block, local ventricular fibrillation, appear to be involved in the causative mechanisms of clinical tachyarrhythmias. A multicausal genesis of at least some of these must be considered seriously, particularly those which occur in acute or chronic coronary heart disease. A recent suggestion that the injury current might be involved in the genesis of ventricular tachyarrhythmias in acute myocardial ischemia and infarction is supported by observations on several properties of this current. Progress has been made in recent years but large gaps in our knowledge of mechanisms causing arrhythmias are still present.

Animals↗
PubMed2001

[Atrial tachycardia, atrial flutter, atrial fibrillation: curative therapy by focal ablation in a pulmonary vein].

We describe the case of a 50-year-old woman with the clinical diagnosis of cardiomyopathy associated with supraventricular tachycardia refractory to pharmacological treatment. The totally irregular tachyarrhythmia was the result of different episodes of atrial tachycardia, atrial flutter and atrial fibrillation that could be identified in the surface ECG. These findings and the patient's symptoms were all caused by a single focal tachycardia originating from the left upper pulmonary vein. Ablation of this focus represented a curative antiarrhythmic therapy also restoring a normalized ventricular function. Thus, an ablation of the AV node with consecutive pacemaker implantation could be prevented.

Atrial Fibrillation↗
PubMed2003

Feasibility of atrial sensing via a free-floating single-pass defibrillation lead for dual-chamber defibrillators.

BACKGROUND: Detection and misclassification of rapidly conducted atrial fibrillation (AF) and marked sinus tachycardia by implantable cardioverter defibrillators (ICD) can result in the delivery of inappropriate therapies. Continuous atrial sensing may improve the differentiation between supraventricular and ventricular tachycardia. The present approach is to implant a separate atrial pacing lead connected to a dual-chamber defibrillator. We hypothesized that a free-floating single-pass defibrillation lead reliably senses the atrial electrical activity. The aim of the study was to assess during implantation the efficacy of a custom-built free-floating single-pass defibrillation lead and to record sinus rhythm (SR), induced AF, and atrial flutter (Afl). METHODS: The free-floating single-pass defibrillation lead (Biotronik, Berlin, Germany) had an atrial bipole with 10 mm spacing and a distance between the atrial bipole and the electrode tip of 13.5, 15 or 17-cm. The lead was temporarily implanted in 15 patients during an ICD implantation. Fifteen seconds recordings were made during SR and after the induction of AF and Afl as well as during induced ventricular fibrillation. The amplitude and the time that the amplitude was less than 0.3 mV were assessed. RESULTS: The amplitude during SR (2.1 +/- 1.4 mV) was significantly higher compared with the amplitudes for Afl (1.3 +/- 0.5 mV; p < 0.02) and AF (0.7 +/- 0.5 mV; p < 0.001). Low amplitudes were not observed during SR and rarely during Afl (1.6 +/- 3.1%), but they were observed 19.9 +/- 15.9% of the time during AF (p < 0.05). The correlation coefficients between SR and AF amplitudes were r = 0.25, between SR and Afl amplitudes r = 0.31, and between AF and Afl amplitudes r = 0.41. During the ventricular fibrillation conversion test 9 patients were in continuous SR. The P-wave amplitude before the induction of ventricular fibrillation was 2.1 +/- 1.4 mV. The signal during ventricular fibrillation decreased to 1.1 +/- 0.7 mV and increased immediately after the termination of ventricular fibrillation to 1.6 +/- 0.8 mV. CONCLUSIONS: The recorded unfiltered signals indicate that SR as well as AF and Afl can immediately be detected after the implantation of the new free-floating single-pass defibrillation lead. High signal amplitude during SR did not predict high amplitude during AF or Afl. During induced ventricular fibrillation the P-wave amplitude decreased intermittently.

Aged↗
PubMed2004

[Catheter ablation of atrial flutter and atrial fibrillation].

Within the past 20 years, refinements in electrophysiologic mapping techniques have provided a better understanding of the pathophysiology of atrial flutter and atrial fibrillation (AF), which resulted in the development of catheter ablation techniques for this arrhythmias. Nowadays, catheter ablation has become the first line treatment of recurrent symptomatic or hemodynamically significant atrial flutter. In contrast, catheter ablation of AF is still an investigational procedure and should be restricted to patients with symptomatic AF who have been refractory to multiple antiarrhythmic drugs. In symptomatic patients with AF and an uncontrolled ventricular rate who have failed treatment with several antiarrhythmic drugs and who do not fit for primary catheter ablation of AF atrioventricular junction ablation with prior pacemaker implantation is recommended.

Anti-Arrhythmia Agents↗
PubMed2004

From bedside to bench: entrainment and other stories.

The concepts of transient entrainment of reentrant rhythms started with studies of overdrive pacing of atrial flutter (AFL) in patients in the immediate period after open heart surgery. Initial studies demonstrated the need to achieve a critical pacing rate and a critical duration of pacing at the critical pacing rate to interrupt AFL. Further pacing studies of AFL, ventricular tachycardia, atrioventricular (AV) reentrant tachycardia, AV nodal reentrant tachycardia, and atrial tachycardia refined the understanding of what occurs during overdrive pacing of reentrant tachycardias, and permitted a mechanistic understanding of transient entrainment as continuous resetting of a reentrant tachycardia to a pacing rate that is faster than the rate of the tachycardia, but which fails to interrupt it. The demonstration of transient entrainment of a tachycardia provides a reliable clinical tool to establish the presence of a reentrant rhythm. Moreover, the principles of entrainment have also been applied clinically to assist in effective application of antitachycardia pacing and catheter ablation techniques.

Arrhythmias, Cardiac↗
PubMed2002

Differentiation of atrial rhythms from the electrocardiogram with coherence spectra.

Automated electrocardiogram (ECG) interpretation systems fail to reliably discriminate atrial fibrillation from sinus rhythm and other more regular atrial arrhythmias. Previously, magnitude-squared coherence (MSC), a frequency domain measure of the linear phase relation between 2 signals, has been shown to be a reliable discriminator of fibrillatory and nonfibrillatory cardiac rhythms when applied to intracardiac electrograms. This study determines whether MSC, when applied to the surface electrocardiogram, would discriminate between atrial fibrillation and nonfibrillatory atrial rhythms. MSC was analyzed by using 2 surface leads of a 10-second ECG. For 68 ECG recordings (23 sinus rhythm, 22 atrial flutter, and 23 atrial fibrillation), MSC was computed between leads II and V1 and the mean MSC in several frequency bands was examined. The performance of MSC was compared to previously published measures of ventricular irregularity and percent power in discriminating atrial fibrillation from nonfibrillatory rhythms. As hypothesized, atrial fibrillation exhibited low coherence in the 2 to 9 Hz band while nonfibrillatory atrial rhythms exhibited relatively moderate to high levels of coherence in the same frequency band. Mean MSC in the 2 to 9 Hz band was significantly lower for atrial fibrillation (range, 0.04 to 0.48; mean +/- SD: 0.15 +/- 0.11) than for sinus rhythm (range, 0.18 to 0.81; 0.47 +/- 0.17) (P <.0005) and atrial flutter (range, 0.06 to 0.80; 0.44 +/- 0.21) (P <.0005). Mean MSC in the 2 to 9 Hz band showed less overlap between atrial fibrillation and atrial flutter than R-R variability and percent power. However, R-R variability showed less overlap between atrial fibrillation and sinus rhythm than mean MSC and percent power. Thus, MSC and RRV both discriminate atrial fibrillation from more organized atrial rhythms. Conversely, percent power was highly variable for both atrial fibrillation and organized atrial rhythms. Results suggest that MSC applied to surface ECG may be used to quantify rhythm organization.

Adult↗
PubMed2004

Prevention of inappropriate therapy in implantable cardioverter-defibrillators: results of a prospective, randomized study of tachyarrhythmia detection algorithms.

OBJECTIVES: The purpose of this randomized study was to investigate the performance of single- and dual-chamber tachyarrhythmia detection algorithms. BACKGROUND: A proposed benefit of dual-chamber implantable cardioverter-defibrillators (ICDs) is improved specificity of tachyarrhythmia detection. METHODS: All ICD candidates received a dual-chamber ICD and were randomized to programmed single- or dual-chamber detection. Of 60 patients (47 male, age 58 +/- 14 years, left ventricular ejection fraction 30%), 29 had single-chamber and 31 had dual-chamber settings. The detection results were corrected for multiple episodes within a patient with the generalized estimating equations method. RESULTS: A total of 653 spontaneous arrhythmia episodes (39 patients) were classified by the investigators; 391 episodes were ventricular tachyarrhythmia (32 patients). All episodes of ventricular tachyarrhythmias were appropriately detected in both settings. In 25 patients, 262 episodes of atrial tachyarrhythmias were recorded. Detection was inappropriate for 109 atrial tachyarrhythmia episodes (42%, 18 patients). Rejection of atrial tachyarrhythmias was not significantly different between both groups (p = 0.55). Episodes of atrial flutter/tachycardia were significantly more misclassified (p = 0.001). Overall, no significant difference in tachyarrhythmia detection (atrial and ventricular) between both settings was demonstrated (p = 0.77). CONCLUSIONS: The applied detection criteria in dual-chamber devices do not offer benefits in the rejection of atrial tachyarrhythmias. Discrimination of atrial tachyarrhythmias with a stable atrioventricular relationship remains a challenge.

Adult↗
PubMed1999

Value of programmed ventricular stimulation in patients with congenital heart disease.

INTRODUCTION: The role of programmed ventricular stimulation (VSTIM) for risk stratification in congenital heart disease is unclear. We analyzed the results of VSTIM in selected congenital heart disease survivors at a single center to determine whether it improved the ability to predict a serious outcome. METHODS AND RESULTS: Between July 1985 and September 1996, 140 primary VSTIM studies were performed on 130 patients (median age 18.1 years, range 0 to 51). Tetralogy of Fallot (33 %), d-transposition of the great arteries (25 %), and left ventricular outflow tract obstruction (12%) accounted for the majority of patients. Indications included spontaneous ventricular tachycardia (VT) of > or = 3 beats (72%) and/or symptoms (68%). Sustained VT was induced in 25% of the studies, and nonsustained VT in 12%. Atrial flutter or other supraventricular tachycardia was documented in 32% and bradyarrhythmias in 26%. By univariate analysis, mortality was increased in patients with positive VSTIM versus negative VSTIM (18% vs 7%, P = 0.04). Using multivariate analysis, positive VSTIM was associated with a sixfold increased risk of decreased survival and a threefold increased risk of serious arrhythmic events, allowing up to 87% sensitivity in predicting mortality. However, 7 (33%) of 21 patients with documented clinical VT had false-negative studies. CONCLUSION: VSTIM in a large, selected group of congenital heart disease patients identified a subgroup with significantly increased mortality and sudden arrhythmic events. Failure to induce VT was a favorable prognostic sign, but the frequency of false-negative studies was high. Frequent supraventricular tachycardia further complicated risk stratification. Although VSTIM appears to be a reasonable tool for evaluation of this population, a larger, multicenter trial is recommended to clarify its utility.

Adolescent↗
PubMed1997

Results of electrophysiologic studies in patients with acute Chagasic myocarditis.

BACKGROUND: As the acute stage of Chagas' myocarditis is rarely detected, little is known about the electrophysiologic characteristics of that stage. HYPOTHESIS: This investigation was undertaken to conduct an electrophysiologic study of the properties of the heart during the acute phase of Chagasic myocarditis. METHODS: We studied eight patients who had positive xenodiagnosis, positive mice culture, and positive complement fixation test for Chagas' disease. RESULTS: Trypanosoma cruzi were identified in all of the patients' stained blood samples. Right ventricular endomyocardial biopsies were obtained, evidencing a distinct infiltrate of lymphocytes that confirmed the diagnosis of acute myocarditis. The cardiac dimensions and the ventricular systolic and diastolic function were preserved in all patients. The electrocardiogram evidenced conduction defects in two patients. The signal-averaged electrocardiogram displayed late potentials in three patients. In the electrophysiologic study, atrial fibrillation or flutter was induced in four patients. When compared with control patients, Chagasic patients were found to have greater values of atrial threshold, A-H interval, and atrioventricular (AV) nodal effective refractory period. The H-V interval was mildly prolonged in two patients, but the dynamic AV nodal conduction was preserved (1:1 conduction during right atrial stimulation at a cycle length of 400 ms) in all the Chagasic patients. The ventricular parameters were within normal limits, and no sustained ventricular arrhythmia could be induced. CONCLUSIONS: Patients with mild acute Chagasic myocarditis may suffer from electrical abnormalities and arrhythmias that are more evident at the supraventricular level and the AV junction.

Acute Disease↗