[Conduction disorders, rhythm disorders].
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Arrhythmias, Cardiac↗
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Arrhythmias and antiarrhythmic agents.
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Anti-Arrhythmia Agents↗
[Treatment of arrhythmias].
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Anti-Arrhythmia Agents↗
[Combination anti-arrhythmia therapy].
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Anti-Arrhythmia Agents↗
Complications in 1000 consecutive treadmill tests.
Complication in 1000 consecutive Tread Mill Tests (TMT) done at the Cardiology Centre of Command Hospital (SC) Pune are reported. The tests were done following Bruce Protocol and analysed based on Selzer's criteria. Complications were noted in 18 cases (1.8%) which included ventricular fibrillation, ventricular tachycardia, atrial fibrillation, malignant VPBs, conduction disturbances, asystole following hyperventilation (HV), complete SA block following HV, atrial flutter following HV, hypotension and severe angina requiring ICCU care. No acute myocardial infarctions or deaths were noted. Coronary arteriography (CART) was done in 50 (5.0%) selected cases including 10 with complications. It is concluded that TMT is a safe procedure if carried out after proper patient selection and under supervision of an experienced and efficient team.
Adolescent↗
Comparison of intravenously administered dofetilide versus amiodarone in the acute termination of atrial fibrillation and flutter. A multicentre, randomized, double-blind, placebo-controlled study.
AIMS: This study compared the efficacy and safety of intravenous dofetilide with amiodarone and placebo in converting atrial fibrillation or flutter to sinus rhythm. METHODS AND RESULTS: One hundred and fifty patients with atrial fibrillation or flutter (duration range 2 h-6 months) were given 15-min intravenous infusions of 8 microg. kg(-1)of dofetilide (n=48), 5 mg. kg(-1)of amiodarone (n=50), or placebo (n=52) and monitored continuously for 3 h. Sinus rhythm was restored in 35%, 4%, and 4% of patients, respectively (P<0.001, dofetilide vs placebo;P=ns, amiodarone versus placebo). Dofetilide was more effective in atrial flutter than in atrial fibrillation (cardioversion rates 75% and 22%, respectively;P=0.004). The mean time to conversion with dofetilide was 55+/-15 min. Dofetilide prolonged the QTc interval (+16% at 20 min). Amiodarone substantially decreased the ventricular rate in non-converters (-18 beats. min(-1)at 30 min). Two patients given dofetilide (4%) had non-sustained ventricular tachycardias, and four (8%) had torsade de pointes, in one case requiring electrical cardioversion. CONCLUSION: Intravenous dofetilide is significantly more effective than amiodarone or placebo in restoring sinus rhythm in patients with atrial fibrillation or flutter. However, when infused intravenously at this dose and rate, dofetilide causes a significant incidence of torsade de pointes.
Acute Disease↗
Cardiothyreosis.
In the present study: (a) physiopathology, (b) clinics, and (c) therapy of cardiothyreosis are discussed. (a) The hyperkinetic syndrome, the earliest clinical sign in thyrotoxicosis (vasodilatation, increase in inotropism, automatism, etc.), is mediated by a two-fold increase in the number of beta-receptors, and supported by an adequate synthesis of ATP and creatinphosphate (CP) in the young and, to a lesser extent, in the elderly. Genetical heart reserves are mobilized, thus significantly increasing the number and the size of mitochondria and also the enzymatic equipment (such as: the alpha-glycerophosphate-dehydrogenase, malic, pentosic cycles, etc.), a.s.o. Due to an excessive adrenergic action (glycogenolysis, an excessive oxygen consumption, up to necrosis, the ATP and CP syntheses dramatically drop; the phosphorus/oxygen ratio decreases to 2 (normal = 4). In this condition, the high functional cardiovascular performances are also impaired (the submaximal effort capacity is attained at a smaller and smaller oxygen consumption; Propranolol 2 mg i.v. decreased the cardiac output by above 30% (vs 10%--normal); electrocardiogram presents aspects of "coronary disease", tachycardia, etc.). An ultrastructural damage occurs: from "mitochondrial disease", partial lysis of myofibrils, to myofibrosis (revealed postmortem), in spite of a reduced degree of coronary atherosclerosis. Ultrastructural and biochemical experimental data support this point of view. (b) The incidence, precocity and severity of the thyrotoxic heart increase with age and the existence of a previous cardiovascular pathology. Cardiothyreosis is not present under 27 years; in 4,353 patients its incidence is of 25% (arrhythmia--21%, heart failure--12%, coronary insufficiency--1-3%). Of a major interest are tachyarrhythmias which may lead to a high mortality by hypodiastolic congestive heart failure, heart failure with secondary hyperaldosteronism, thromboembolic episodes and ventricular fibrillation. Thyrotoxicosis favours the disease of papillary muscles--mitral prolapse and insufficiency, reversible especially in children. (c) The treatment of thyrotoxic heart is an etiologic one (medical, surgical, radioactive--the last two being preferable after the adequate medical therapy). In particular, cardiothyreosis requires a reinforced irradiation (10,000 rads instead of 7,000 rads) in smaller 131I doses. The protection against the increased nocivity of catechols in thyrotoxicosis is very important (which explains the high mortality in the thyrotoxic "storm") and requires propranolol; doses above 2 mg/kilo body/day are recommended. In the elderly, the sensitivity to propranolol decreases: verapamil i.v. is more efficient in paroxysmal tachyarrhythmias (flutter, atrial fibrillation) and in those occurring intra-operatively during halothane narcosis. The anticoagulant therapy is administered in tachyarrhythmias with high ventricular rate, especially in the elderly, to avoid the embolic risk, higher in defibrillation condition.(ABSTRACT TRUNCATED AT 400 WORDS)
Angina Pectoris↗
Bundle branch reentry tachycardia and possible sustained interfascicular reentry tachycardia with a shared unusual induction pattern.
A case of bundle branch reentry tachycardia with an unusual induction pattern is presented. Unlike typical cases of this arrhythmia in which tachycardia is usually inducible with routine programmed ventricular stimulation and/or short-long sequences, tachycardia in this case was inducible only with atrial stimulation. It also arose spontaneously during atrial flutter and during isoproterenol administration. After ablation of the right bundle, possible interfascicular reentry tachycardia with a similar induction pattern was observed. This tachycardia was successfully ablated in the region of the posterior fascicle of the left bundle branch.
Aged↗
Torsade de pointes induced by ajmaline.
Ajmaline, a reserpine derivative, is an effective class I antiarrhythmic agent. Herein we report two cases of ajmaline-induced abnormal QT prolongation accompanied by polymorphic ventricular tachycardia of the torsade de pointes type. Since ajmaline is increasingly used for the acute termination of wide complex tachycardia and as a diagnostic tool after syncope and in patients with idiopathic ventricular tachyarrhythmias, our observations suggest that caution should be exercised with regard to the effects of the drug on the QT interval and its potency to induce proarrhythmia of the torsade de pointes type.
Ajmaline↗
Focal right atrial dysplasia and atrial flutter in a patient with myotonic dystrophy.
Focal dysplasia of the right atrium was identified postmortem in a 22-year-old man with myotonic dystrophy and sudden death. Antemortem cardiac abnormalities included a single syncopal episode associated with atrial flutter with exercise-induced 1:1 atrioventricular conduction, sinus node dysfunction, and mild mitral valve prolapse. Pathologically there was only mild conduction system disease and the ventricular myocardium was normal. Right atrial dysplasia, previously unreported in myotonic dystrophy, appears to have been an arrhythmogenic lesion in this patient, serving as a morphological substrate for reentry.
Adult↗
[Pericarditis and fresh myocardial infarction (author's transl)].
Among 400 patients with myocardial infarction who had been admitted to the intensive care department, pericarditis was observed in 64 cases (16%). It occurred more frequently with anterior wall infarctions. The influence of the pericarditis on the mortality and complications threatening in the acute period were particularly investigated: There was no significant difference with regard to the mortality (20.6% in the group with pericarditis, 26.2% in the control group) or the occurrence of cardiac insufficiency or arrhythmias as complications. Atrial flutter, however, is more frequent (25% against 15%). Anticoagulant therapy was discontinued when pericarditis appeared, with one exception. In spite of the high frequency of atrial flutter, embolic complications were not more frequent after discontinuing the anticoagulant therapy. A postmyocardial infarction syndrome was observed seven times (1.7%), it was frequently found in a pericarditis with angina pectoris (4/7) and with ventricular aneurysm (3/7). Hemopericardium occurred in one patient in whom anticoagulant therapy had not been discontinued.
Acute Disease↗
Oral class III antiarrhythmics: what is new?
PURPOSE OF REVIEW: This review describes the latest developments in the clinical usage of class III antiarrhythmics. It also discusses some new studies providing insight into the mechanism of action of these drugs. RECENT FINDINGS: New data suggest that amiodarone is one of the most effective drugs for management of ventricular as well as supraventricular tachyarrhythmias. As over the years we have learned to deal with the toxic side effects of this drug, the risk of bradyarrhythmias requiring placement of a pacemaker is becoming more significant. Sotalol was approved for treatment of atrial fibrillation and atrial flutter (AF). It was also found to be effective in management of postoperative AF. Dofetilide has been approved for the conversion and maintenance of sinus rhythm in AF; its role in ventricular arrhythmias remains unclear. Data are emerging regarding clinical efficacy of azimilide and dronedarone. SUMMARY: Management of arrhythmias in patients with structural heart disease remains a challenge. Class III antiarrhythmics are the mainstay of treatment in this group of patients.
Amiodarone↗
A frequency domain analysis of spatial organization of epicardial maps.
Mapping of organized rhythms like sinus rhythm uses activation times from individual electrograms, and often assumes that the map for a single activation is similar to maps for subsequent activations. However, during fibrillation, activation times and electrograms are not easy to define, and maps change from activation to activation. Volume and complexity of data make analysis of more than a few seconds of fibrillation difficult. Magnitude Squared Coherence (MSC), a frequency domain measure of the phase consistency between two signals, can be used to help interpret longer data segments without defining activation times or electrograms. Sinus rhythm, flutter, and fibrillation in humans and swine were mapped with an array of unipolar electrodes (2.5 mm apart) at 240 sites on the atrial or ventricular epicardium. Four-second data segments were analyzed. One site near the center of the array was chosen ad hoc as a reference. MSC maps were made by measuring mean MSC from 0-50 Hz between every point in the array relative to the reference. Isocoherence contours were drawn. The effects of bias in the coherence estimate due to misalignment were investigated. Average MSC versus distance from the reference was measured for all rhythms. Results indicate that in a 4-s segment of fibrillation, there can exist some phase consistency between one site and the reference and little or none between a second site and the reference even when both sites are equidistant from the reference. In fibrillation, isocoherence contours are elongated and irregularly shaped, reflecting long-term, but nonuniform, spatial organization. That is, activation during fibrillation cannot be considered as random over a 4-s interval. Bias in the coherence estimate due to misalignment is significant for sinus rhythm and flutter, but can be corrected by manual realignment. Average MSC drops with distance for all rhythms, being most pronounced for fibrillation, MSC maps may provide insights into long-term spatial organization of rhythms that would otherwise be cumbersome and difficult to interpret with standard time domain analysis.
Animals↗
[Intra-atrial cardioversion in supraventricular tachycardial arrhythmia].
Cardioversion by rapid atrial stimulation has been carried out in 29 patients with supraventricular tachycarida and 12 patients with "coarse" atrial fibrillation. Atrial stimulation rates of 60-1200/min and electrical impulses of 6-25 mA were used. Intracardial conversion was successful in 86% of the cases presenting supraventricular tachycardia. Cardioversion was not achieved with atrial fibrillation but atrial flutter and atrial tachycardia were both found to be easily converted. Transformation of an arrhythmia into sinus rhythm or into stable atrial fibrillation with a slowed ventricular rate was the criterion for a successful conversion. Transient arrhythmias prior to an eventual stable rhythm was observed in 28% of the cases. Two mechanisms to explain the induced change in supraventricular tachycardias are discussed: (1) interruption of atrial or junctional foci (overdrive suppression) and (2) interruption of a re-entry circle by single premature beats. Cardioversion using atrial stimulation is indicated in atrial flutter, atrial tachycardias and junctional tachycardias. The method is of advantage in that it does not require anesthesia or interruption of digitalis therapy and its use involves no complications. Cardioversion using DC-shock is to be preferred in all cases of atrial fibrillation.
Adult↗
[Radiofrequency ablation as the first line of treatment in patients with common atrial flutter. The arguments pro].
Radiofrequency ablation of atrial flutter may be performed nowadays with 90% probability of success, 10% of recurrences and a very low risk of complications; thus the indications of the procedure have lately expanded. However, there are still many discrepancies among different groups in the way to approach the acute and the chronic therapy for atrial flutter. Acute as well as chronic antiarrhythmic therapy has a limited effectivity and carries a risk of proarrythmia and extracardiac secondary effects. On the other hand, the potential risk of embolism during chronic therapy and after cardioversion is often underestimated. Another important issue often neglected is the tachycardiomyopathy secondary to the sustained high rate at the atrium and also at the ventricular level. The delay in the definitive therapy worsens the atrial remodelling and may promote the development of atrial fibrillation. We consider that radiofrequency ablation of atrial flutter is the first therapeutic option, and it should be attempted when the patient is seen, without further delay. In that way, the above mentioned potential risks are avoided, and for this reason, this is our common approach to therapy.
Anticoagulants↗
Management of atrial tachyarrhythmias. Rhythm control using implantable devices.
Presently, most devices with atrial diagnostic and therapeutic features are implanted in patients for electrical treatment of bradyarrhythmias and ventricular tachyarrhythmias. The painless electrical strategies for prevention and termination of ATa have not demonstrated significant clinical effectiveness in the general population with ATa. The effectiveness of ATP in reducing burden may be significantly higher in a subgroup of patients with a high incidence of stable ATa, but this needs to be evaluated prospectively. Smart sensing and detection schemes will also help provide accurate information and determine when ATa can be terminated with ATP. Although electrical defibrillation is effective, the discomfort associated with atrial shocks has limited the widespread use of this technology. Recent technological advances have increased the capabilities of implantable devices to store large amounts of diagnostic information. In the near future, implantable devices without transvenous leads may be implanted to monitor a variety of physiologic signals. This could help improve clinical outcomes and determine which therapies (pharmacologic, ablative, or electrical) would be most effective as well as monitor their safety and efficacy. Frequent monitoring from home and the availability of this data to the physician/nurse on the Internet can potentially improve the management of patients' ATa at a much lower cost.
Atrial Flutter↗
[Ablative strategy: a definite treatment for cardiac arrhythmias?].
The development of radiofrequency catheter ablation has dramatically changed the therapeutic approach of cardiac arrhythmias. All atrial rhythm disturbances are now amenable to ablative strategy. Ablation has become the first-line therapy for atrial flutter. Atrial fibrillation, a major factor of morbidity and mortality, is now a target for this radical treatment. Ablation of pulmonary vein foci, eventually associated to atrial linear lesions, raises the possibility of suppressing atrial fibrillation. The success rate is now as high as 70 to 85%, depending on the form of atrial fibrillation. For atrioventricular reentrant tachycardia either nodal or over an accessory pathway, ablation is the reference treatment with success rates of 99%. All symptomatic Wolff-Parkinson-White syndromes can be definitely cured by this technique. At the ventricular level, the procedures are often more complexes, due to advanced cardiomyopathy. However, most of sustained ventricular tachycardias can be cured by ablation. The success rates are somewhat lower (about 80%). The challenge for the next years is ablation of premature ventricular beats initiating ventricular fibrillation. The technique is also improving from day-to-day (88% success rate) and makes rise the hope of curing sudden death.
Arrhythmias, Cardiac↗
[Evaluation of infrequent episodes of palpitations with a patient-activated hand-held electrocardiograph].
UNLABELLED: The disadvantage of most devices presently available for cardiac rhythm event monitoring is that they require either permanently attached electrodes or the subcutaneous implantation of the device. The aim of the study was to evaluate the feasibility and diagnostic yield of a hand-held, portable electrocardiograph for the evaluation of infrequent episodes of palpitations. In contrast to other devices, this electrocardiograph records and stores the electrocardiograms with integral electrodes, which makes long-term attached electrodes not unnecessary. METHODS: The study included 55 consecutive patients with palpitations less than once a week. The patients received the electrocardiograph Miniscope MS-3 with integral tripod electrodes (Schiller AG, Switzerland) to record a one-channel electrocardiogram during a recurrent episode. The frequency of device activation and the atrial rhythm during an episode was assessed. RESULTS: Forty-one (75%) patients had at least one episode within 38 +/- 22 days. The first episode occurred within the first week in 18 cases, during the 2nd in 9, during the 3rd in 9, during the 4th in 2 patients, and in 3 patients between the 4th and 12th week. All episodes could be properly analyzed: Twenty-three patients had sinus rhythm, 7 paroxysmal atrial fibrillation, 7 paroxysmal atrial flutter, and 4 an AV node reentry tachycardia. Eleven of the 23 patients with sinus rhythm additionally had premature atrial or ventricular contractions. Mean heart rate was 111 +/- 45 bpm. A second episode was recorded in 22 and a third episode in 12 patients. All patients had during the subsequent episode the same cardiac rhythm as during their first episode. CONCLUSIONS: Patients evaluated for their infrequent palpitations had during event monitoring a recurrent episode in 75% that occurred in 88% within the first 4 weeks. All patients were able to activate the electrocardiograph and could store an electrocardiogram with the integral electrodes. Patient-activated event monitoring reliably identified patients with an atrial arrhythmia who need further invasive evaluation and treatment, and ruled out patients with sinus rhythm and premature contractions.
Adult↗