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Cardiac arrhythmias in the athlete: the evolving role of electrophysiology.

Arrhythmia management has undergone a revolution in the past decade. The diagnosis and treatment of arrhythmias in the athlete can be complicated by the need to compete and exercise. Some arrhythmias may be benign and asymptomatic, but others may be life threatening. Sinus bradyarrhythmias are common and even expected in athletes; these are rarely a cause for concern. Heart block is unusual and merits a thorough work-up. Atrial fibrillation may be more common in the athlete, and supraventricular tachycardias other than atrial fibrillation warrant consideration of radiofrequency ablation for cure. Ventricular arrhythmias in the athlete generally occur in the setting of structural heart disease that is genetically determined (hypertrophic cardiomyopathy, arrhythmogenic right ventricular dysplasia, anomalous coronary arteries), or acquired (coronary artery disease, myocarditis, idiopathic dilated cardiomyopathies). In these conditions the arrhythmia is life threatening. Ventricular arrhythmias that occur in the athlete without structural heart disease are not thought to be life threatening. Athletes with structural heart disease and those with exertional syncope merit a complete evaluation.

Arrhythmia, Sinus↗

[Late postoperative cardiac arrhythmias after total cavopulmonary anastomosis and correlation with age of the patients at operation].

Late postoperative arrhythmias are a common problem associated with significant morbidity following Fontan operations. We analyzed in our patients whether age at the time of a modified Fontan procedure (total cavopulmonary connection) has an influence on the frequency of late postoperative arrhythmias. We examined all 66 long-term surviving patients who underwent a total cavopulmonary connection (TCPC) in our center during a nine year period. At the time of TCPC, 31 children were younger (group I) and 35 children were older than 4 years (group II). The follow-up period was almost identical in both groups (group I: 4.29 years, group II: 4.52 years). We evaluated all ecgs performed at maximum intervals of 6 months and all Holter ecgs performed at intervals of 12 months. Atrial tachyarrhythmias (supraventricular tachycardias, atrial flutter) were registered in six patients (9%). All of these patients belonged to group II (17%). Ventricular arrhythmias (couplets, ventricular tachycardia) were found in 3% of the younger and 17% of the older patients. Abnormalities of sinus node function were registered in equal frequency in younger and older children (group I: 35%, group II: 31%), while pauses with a duration of > 2 s where present only in older children (group II: 14%). Pacemaker implantation or antiarrhythmic therapy became necessary in 10/66 patients (15%) affecting none of the children who underwent the TCPC < 4 years (group I) but 10/35 children (group II) who underwent the TCPC at an older age (29%). According to our findings in the medium-term follow-up after TCPC, atrial tachyarrhythmias and complex ventricular arrhythmias are registered less frequently in children who underwent the modified Fontan procedure at an age of less than 4 years. Although further studies will have to show whether these differences persist in the long-term follow-up, these findings represent an additional argument for the elective performance of modified Fontan operations at an age of less than 4 years.

Adolescent↗

Ethmozin. I. Effects of intravenous drug administration on paroxysmal supraventricular tachycardia in the ventricular preexcitation syndrome.

Electrophysiologic effects of intravenous ethmozin (1.5 to 2 mg/kg) were evaluated in 16 patients (10 with Wolff-Parkinson-White [WPW] syndrome and six with concealed accessory pathway [AP]) with ventricular preexcitation syndrome. Ethmozin terminated induced supraventricular tachycardia (SVT) in 9 of 14 patients and atrial flutter with anterograde conduction 2: 1 over AP in one patient. The drug prevented induction of sustained SVT in 8 of 14 patients (four with WPW syndrome and four with concealed AP). The drug significantly lengthened the cycle length of induced SVT in WPW syndrome (381 +/- 24 to 421 +/- 27 msec) and in concealed AP (313 +/- 19 to 343 +/- 15 msec), mainly because of prolongation of the ventriculoatrial (VA) interval; the drug increased SVT atrial zone in WPW syndrome and removed or decreased it in patients with concealed AP. The drug abolished anterograde (6 of 10 patients) and retrograde (3 of 16 patients) conduction over AP, and/or increased anterograde and retrograde refractoriness of AP in all patients. Ethmozin significantly lengthened the following: PA (27 +/- 2 to 40 +/- 3 msec), AH (92.6 +/- 6 to 107 +/- 8 msec), and PR intervals (175 +/- 9 to 202 +/- 15 msec), and refractoriness of VA conduction systems. The refractoriness of atrioventricular node, HV, QRS, and QT intervals and the spontaneous sinus cycle length did not change significantly. Thus intravenous ethmozin terminated induced SVT and prevented the induction of sustained SVT in most patients with preexcitation syndrome due to a suppressive effect of the drug on AP.

Adolescent↗

Unusual cardiac manifestations in a patient with myotonic muscular dystrophy.

We report on a patient with myotonic muscular dystrophy in whom mitral valve prolapse associated with prolonged PR interval and left anterior hemiblock was documented 3 years before any clinical evidence of myotonia, muscle weakness or wasting. One year after diagnosis had been established, he developed atrial flutter with 1:1 atrioventricular conduction, an arrhythmia that in addition to complete heart block and ventricular arrhythmias may account for the occurrence of syncope and sudden death in this group of patients.

Adult↗

The N + 1 difference: a new measure for entrainment mapping.

OBJECTIVES: The purpose of this study was to develop and test a new entrainment mapping measurement, the N + 1 difference. BACKGROUND: Entrainment mapping is useful for identifying re-entry circuit sites but is often limited by difficulty in assessing: 1) changes in QRS complexes or P-waves that indicate fusion, and 2) the postpacing interval (PPI) recorded directly from the stimulation site. METHODS: In computer simulations of re-entry circuits, the interval from a stimulus that reset tachycardia to a timing reference during the second beat after the stimulus was compared with the timing of local activation at the site during tachycardia to define an interval designated the N + 1 difference. The N + 1 difference was compared with the PPI-tachycardia cycle length (TCL) difference in simulations and at 65 sites in 10 consecutive patients with ventricular tachycardia (VT) after myocardial infarction and at 45 sites in 10 consecutive patients with atrial flutter. RESULTS: In simulations, the N + 1 difference was equal to the PPI-TCL difference. During mapping of VT and atrial flutter, the N + 1 difference correlated well with the PPI-TCL difference (r > or = 0.91, p < 0.0001), identifying re-entry circuit sites with sensitivity of > or = 86% and specificity of > or = 90%. Accuracy was similar using either the surface electrocardiogram or an intracardiac electrogram (Eg) as the timing reference. CONCLUSIONS: The N + 1 difference allows entrainment mapping to be used to identify re-entry circuit sites when it is difficult to evaluate Egs at the mapping site or fusion in the surface electrocardiogram.

Aged↗

Fetal arrhythmias: a 3-year experience.

Eight cases of fetal arrhythmia were seen over a 3-year period. Two had atrial and/or ventricular extrasystoles, 1 had complete atrioventricular block and 5 had tachyarrhythmias--3 supraventricular tachycardia, 1 atrial flutter and 1 ectopic atrial tachycardia. All had structurally normal hearts. Nonimmune hydrops fetalis was the initial presentation in 3 of the 5 cases with tachyarrhythmias. There were 2 deaths--a stillbirth and a neonatal death, while 2 others required neonatal intensive care. The 6 survivors have remained well and are now off treatment. The diagnosis, careful assessment and management of a fetal arrhythmia may lead to a successful outcome. The complexity of the problems experienced may warrant early referral to a tertiary centre where the overall management of the mother, fetus and neonate, may be undertaken.

Arrhythmias, Cardiac↗

Azimilide pharmacokinetics following intravenous and oral administration of a solution and capsule formulation.

Azimilide dihydrochloride (NE-10064) is a novel class III anti-arrhythmic agent that blocks both the slowly and rapidly acting components of the delayed rectifier potassium current of human atrial and ventricular myocytes. In clinical studies, azimilide reduced the frequency of symptomatic episodes of atrial fibrillation, atrial flutter, and paroxysmal supraventricular tachycardia. This study was conducted to characterize azimilide pharmacokinetics following single-dose administration of a 1 mg/kg intravenous infusion (18 min), 2 mg/kg oral solution, and a 150 mg orally administered capsule. This was a three-period, randomized, crossover study in 27 healthy, drug-free (including caffeine and alcohol), non-smoking male volunteers (mean [SD]; age, 25.9 [1.0] years; weight 74.3 [0.7] kg; 23 Caucasians and 4 Hispanics). Blood and urine samples were collected for 27 days and analyzed for azimilide using HPLC with UV detection. Subjects were monitored for adverse events and abnormalities in clinical laboratory tests, vital signs, and electrocardiography (including Holter monitoring). Mean (%CV) azimilide parameters were total clearance = 0.143 L/h/kg (38%), renal clearance = 0.014 L/h/kg (35%), steady-state volume of distribution = 13.2 L/kg (23%), and terminal exponential half-life = 78.8 h (44%). Similar parameter estimates were obtained following oral administration. Both the oral solution and capsule formulations were completely absorbed. In addition, the rate (Cmax) and extent of absorption (AUC) following oral administration of the capsule dosage form were bioequivalent to the oral solution with means for times of maximum blood concentration of 7.08 and 7.18 hours for the oral solution and capsule, respectively. Azimilide dihydrochloride was generally well tolerated in all subjects.

Administration, Oral↗

Intracardiac electrophysiologic techniques in recurrent syncope of unknown case.

Twenty-five patients with recurrent episodes of syncope, unexplained despite thorough medical and neurologic evaluation, underwent intracardiac electrophysiologic study with programmed stimulation. Electrophysiologic study yielded a presumptive diagnosis in 17 patients: nine with rapid ventricular tachycardia by programmed stimulation, three with intra-His conduction delays, one with symptomatic atrial flutter, one with sick sinus syndrome, and three with persistent hypervagotonia manifested as atropine-reversible prolongation of atrioventricular nodal refractoriness. Therapy based on these findings provided complete symptomatic relief in 14 and improvement in one of these 17 patients during a mean follow-up of 18 +/- 10 months. Therapy based on electrophysiologic testing was ineffective in two of the 17 patients. Syncope persisted in four of the eight patients in whom electrophysiologic study did not define a probable arrhythmic mechanism. These observations indicate that full electrophysiologic evaluation with programmed stimulation is useful in the diagnosis and therapy of recurrent unexplained syncope.

Adolescent↗

[Usefulness of the electrophysiologic study in the prognostic evaluation of patients with syncope of uncertain origin].

UNLABELLED: Recurrent, sudden temporary loss of consciousness is a common clinical problem: in the absence of electrocardiographic monitoring during a syncopal episode (S), abnormalities demonstrated by an electrophysiological study (ES) may suggest the etiology of S. We have performed a complete ES in 53 Pts (M. 38-F. 15, mean age 63 y.) with recurrent unexplained S (3.8 S/pt) by means of a standardized protocol. Group I: 30 Pts (mean age 65 y, 3.6 S/pt) with structural heart disease. Thirteen of these had abnormal ES findings: inducible ventricular tachycardia in 6, prolonged HV interval in 7 (with bundle branch block), very fast atrial flutter in one. Group II: 23 Pts (mean age 61 y., 3, 9 S/pt), without organic heart disease. The ES was abnormal in 14 Pts showing a prolonged HV interval in 11 (with bundle branch block), an intrahisian block in 1 and an inducible AV nodal tachycardia with heart rate greater than 200/m' in one. Only the Pts with abnormal ES were treated according to their condition with amiodarone or with an implantable pacemaker. Three PTs with C.H.D. and normal ES successfully underwent by-pass surgery. During the follow-up (20 months) therapy based on ES provided symptomatic relief (no S) in 25 of 26 Pts with abnormal electrophysiological study. Syncope persisted in 4 of 26 Pts in whom ES did not define a mechanism of S. No sudden death in any Pt. CONCLUSIONS: ES was, therefore, of diagnostic value in more than half of the patients with syncope of unknown cause and long-term treatment based on ES was successful in the prevention of S (remission rate of 93% in patients treated with amiodarone or pacemaker).

Adult↗

[Does closely monitored control and therapy adjustment improve the prognosis in patients with severe heart insufficiency?].

The one year mortality of patients with severe congestive heart failure ranges between 30 and 70%. The effect was investigated of a stepped care program, including weekly monitoring and frequent adjustment of medical treatment, on the prognosis of 18 consecutive outpatients with severe congestive heart failure (NYHA class III and IV, 60 +/- 3.5 years). The diagnosis of congestive heart failure was proven by an invasively measured cardiac index below 2.5 l/min/m2 or by a left ventricular ejection fraction below 30%. Plasma adrenaline and noradrenaline values and plasma renin activity were substantially increased in all patients compared with 20 normals. 11 of the heart failure patients had coronary heart disease, 10 with a large left ventricular aneurysm, 6 patients had congestive cardiomyopathy and one patient had valvular heart disease with aortic insufficiency. In 9 patients ventricular tachycardias were registered, four had recurrent syncopes, and in 7 other patients atrial fibrillation, atrial flutter and paroxysmal supraventricular tachycardias were found. Medical treatment in all patients included pre- and afterload reduction by vasodilators. 11 patients received digoxin and 8 antiarrhythmic drugs. After a mean follow-up of 25 +/- 3.3 months, the one-year mortality was 7% and the two year mortality 15%. The favorable prognosis in patients in this special care program shows the favorable effects of individualized therapy, of frequent patient monitoring and the influence of strict compliance on survival and symptoms in patients with chronic congestive heart failure.

Adult↗

[Anti-arrhythmic activity of the beta2-adrenoblockader alpheprol].

Experiments were conducted on dogs, cats and rats in which various disturbances of the cardiac rhythm were induced. Beta2-adrenoblocker alpheprol proved to produce a marked antiarrhythmic action. The preparation arrested the auricular arrhythmias caused by electric stimulation of the auricles or by aconitine application, eliminated the auricular arrhythmias resulting from occlusion of a branch of the coronary artery or oubaine intoxication, prevented lethal auricular fibrillation in rats after the calcium chloride intoxication. It is supposed that along with the beta-adrenoreceptor block the antiarrhythmic effect of alpheprol was also caused by quinidine-like action of the preparation.

Alprenolol↗

[The first original Russian class-III antiarrhythmic nibentan].

The paper presents experimental and clinical findings of the new antiarrhythmic drug nibentan. The agent was found to be a class-III antiarrhythmic agent in terms of its electrophysiological effects and an inhibitor of the delayed rectifier potassium current in terms of its effects on the ionic channels of cardiomyocytes. The clinical trial of nibentan shows that the drug is highly effective (in 70-100% of cases) in patients with atrial flutter and fibrillation and in those with supraventricular tachycardia and it is less effective in suppressing ventricular premature contractions and tachycardia. The rate of arrhythmogenic effects produced by the drug was inversely related to its antiarrhythmic action. Nibentan has been approved for clinical use.

Animals↗

Ventricular fibrillation and sudden death after radiofrequency catheter ablation of the atrioventricular junction.

Two hundred thirty-five patients underwent RF catheter ablation of AV conduction for symptomatic drug refractory AF (84%), atrial flutter (9%), and atrial tachycardia (7%). In the first 100 patients, postablation pacing was not prospectively set at any specific rate and was always < or = 70 beats/min. In the next 135 patients, postablation pacing was prospectively set at 90 beats/min for 1-3 months. Six of the first 100 patients (6%) had VF or sudden death after the RF procedure and none (0%) of the next 135 patients did (P < 0.05). One of the six patients had recurrent VF 4 days after the ablation. Five patients were successfully resuscitated and one patient died. There were no statistically significant differences between patients with and without (aborted) sudden death or between the first 100 and the next 135 patients with respect to age, sex, underlying heart disease, EF, number of RF applications, or left-or right-sided approach of the procedure. VF mostly occurred during episodes of slow ventricular escape rhythms or during slow ventricular pacing. We conclude that malignant ventricular arrhythmias and sudden death are possible complications of RF ablation of the AV function. The mechanism of these complications could have a bradycardia dependent nature and it seems that the occurrence of malignant arrhythmias can be prevented by temporarily pacing the heart at relatively fast rates immediately after ablation.

Aged↗

Clinical utility and the predictors of outcome of overdrive transesophageal atrial pacing in the treatment of atrial flutter.

Transesophageal atria pacing (TEAP) using a pill electrode was performed in 49 patients with atrial flutter. The responses observed were (1) immediate sinus rhythm in 17 (35%), (2) delayed sinus rhythm in 13 (27%), (3) atrial fibrillation in 11 (22%), and (4) no success in 8 (16%) patients. Sinus rhythm was thus restored in 30 patients (61%). In group A, 12 of 17 patients (p < 0.05) had coronary artery disease. The patients in group D had echocardiographic evidence of right atrial enlargement (2.56 +/- 0.29 cm, p = 0.007), left atrial enlargement (4.6 +/- 0.12 cm, p < 0.0001), right ventricular dilatation (3.41 +/- 0.45 cm, p < 0.05), left ventricular dilatation (6.39 +/- 0.66 cm, p < 0.05), and depressed left ventricular ejection fraction (32 +/- 7%, p < 0.05). Optimal pacing rate (375 +/- 54 beats/min) was 41% higher than the mean atrial flutter rate (266 +/- 37 beats/min) for cardioversion to immediate sinus rhythm. Pacing current strength and the pulse width had no influence on the final outcome. On the basis of the result of the initial attempt, patients undergoing TEAP repetitively had an almost predictably similar outcome on the subsequent attempts. Thus, normal sinus rhythm could be resumed in most patients with atrial flutter by TEAP. It does not require general anesthesia and can be performed even in patients who have undergone digitalization, when a direct-current countershock may be of some concern.

Aged↗