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PubMed1977

Multifocal atrial tachycardia.

Multifocal atrial tachycardia (MAT) was observed in 41 patients, 35 of whom were in acute respiratory distress. A hospital mortality of 37% reflected the seriousness of their underlying conditions. In no patient was the arrhythmia the primary cause of death. The MAT preceded and/or followed atrial fibrillation (AF) or atrial flutter (Af) in 19 patients (46%). The MAT simulated AF in several cases in which P-waves were inconspicuous. Our cases suggest that MAT is not a manifestation of digitalis intoxication. Quinidine sulfate, procainamide hydrochloride, lidocaine, and phenytoin (diphenythydantoin) did not affect the rhythm. Digitalis was usually not effective in slowing the ventricular response in patients with MAT. Propranolol hydrochloride was given to seven patients and was effective in slowing the atrial rate in all cases. An attempt at electrocardioversion was unsuccessful in one patient.

Aged↗

PubMed1988

Safety and efficacy of amiodarone. The low-dose perspective.

Amiodarone has been reported to be a remarkably safe and effective drug in the European and South American experience but American investigators have published conflicting data. Since this disparity may be explained by a different dosing schedule, we prospectively evaluated the safety and efficacy of a low dose regimen in a group of 68 patients with cardiac arrhythmia resistant to conventional therapy, of whom 57 had manifested either ventricular tachycardia or fibrillation. All were loaded either intravenously (17) or orally, and maintained on an oral dose of 200 to 600 mg/day (mean daily dose 317 +/- 114 mg) and followed for 4 to 58 months (22 +/- 11). Results indicated that amiodarone was a safe and effective antiarrhythmic drug when used in lower doses.

Amiodarone↗

PubMed1993

Atrial fibrillation and atrial flutter.

The epidemiology, pathophysiology, diagnosis, evaluation, and treatment of atrial fibrillation (AF) and atrial flutter (AFl) are reviewed, and recent developments and controversies in the approach to these arrhythmias are addressed. AF and AFl are the arrhythmias most frequently encountered in clinical practice. Although occasionally unaware of their arrhythmia, patients usually complain of palpitations, weakness, dyspnea, and decreased exercise tolerance. The initial goal of therapy is control of the ventricular rate. Rate control is accomplished with atrioventricular node-blocking agents such as digoxin, calcium-channel blockers, or beta-adrenergic blockers. Along with a rapid, irregular ventricular response, other detrimental outcomes of AF and AFl include compromised hemodynamics and increased vulnerability to thromboembolism. After the cause of the patient's arrhythmia has been evaluated, pharmacologic treatment is directed at converting the rhythm to normal sinus rhythm and maintaining it. Antiarrhythmic drugs have proved effective in about 50% of cases but may be associated with increased mortality. More effective and safer forms of drug therapy for AF and AFl are needed. Nonpharmacologic alternatives to antiarrhythmic medications for refractory AF and AFl include radio-frequency catheter ablation of the bundle of His with pacemaker placement and surgery. Patients who remain in AF despite therapy should receive long-term warfarin treatment. Drugs may be used to control the ventricular response in patients with AF and AFl, terminate and prevent the arrhythmias, and prevent thromboembolism. Nonpharmacologic treatments are reserved for patients whose arrhythmias are poorly controlled by drugs.

Adrenergic beta-Antagonists↗

PubMed2001

Indications for dual-chamber cardioverter defibrillators at implant and at 1 year follow-up: a retrospective analysis in the single-chamber defibrillator era.

AIM: This retrospective four-centre study assessed the current indications for dual-chamber implantable cardioverter defibrillators (ICDs) at implant and during a medium-term follow-up period in a group of patients treated by single-chamber ICD in the pre dual-chamber ICD era. METHODS AND RESULTS: The study population consisted of 153 consecutive patients (127 males, mean age 58 +/- 6 years) treated by single-chamber ICD for ventricular tachycardia and/or ventricular fibrillation. Definite indications for having a dual-chamber ICD included the presence of sinus node dysfunction and of second- or third-degree atrioventricular (AV) block, while possible indications were represented by paroxysmal atrial fibrillation or flutter and first-degree AV block. At implant, dual-chamber ICD would appear definitely indicated in 10.5% of cases, and possibly indicated in an additional 17.5% of cases. During 12 +/- 10 months follow-up, such percentages remained stable (11 and 19.5%, respectively). Inappropriate ICD intervention was documented in five of 13 patients (38%), with episodes of paroxysmal atrial fibrillation or flutter. CONCLUSION: In this non-selected study population, a dual-chamber ICD would have potentially benefited approximately 30% of the patients. During medium-term follow-up, there was no progression towards increasing dual-chamber ICD indications. The 15% cumulative incidence of paroxysmal atrial tachyarrhythmias justifies the activation of dedicated detection algorithms.

Adult↗

PubMed1987

Antiarrhythmic, electrophysiologic and hemodynamic effects of ACC-9358.

The antiarrhythmic, electrophysiologic and hemodynamic effects of a new antiarrhythmic agent, ACC-9358, were evaluated. In anesthetized dogs, ACC-9358 converted ouabain-induced ventricular tachycardia to normal sinus rhythm at a cumulative dose equal to encainide or flecainide and less than disopyramide. In 24-hr coronary artery ligated dogs, ACC-9358 suppressed spontaneous ventricular arrhythmias for up to 6 hr after oral or i.v. administration. The antiarrhythmic effect and plasma concentrations of ACC-9358 correlated well for both oral (r = 0.88) and i.v. (r = 0.87) administration. ACC-9358, flecainide and disopyramide were equieffective in converting crush-stimulation-induced atrial flutter in anesthetized dogs to normal sinus rhythm. In alpha-chloralose-anesthetized, closed-chest dogs, ACC-9358 slowed impulse conduction through the atria, atrioventricular node, His-Purkinje system and ventricles and prolonged atrial functional refractory period. In conscious dogs, ACC-9358 increased heart rate, reduced stroke volume and had no effect on mean arterial pressure, systemic vascular resistance or cardiac output. In alpha-chloralose-anesthetized dogs, ACC-9358-induced sinus tachycardia was unaffected by propranolol but was blocked by hexamethonium or vagotomy. In isolated cat ventricular muscle, the IC50 for the negative inotropic effect of ACC-9358 was significantly greater than flecainide or disopyramide. These results indicate that ACC-9358 is a potent, broad-spectrum, long-acting, orally and intravenously active class Ic antiarrhythmic agent that 1) may be devoid of active metabolites, 2) exerts little or no vascular effects and 3) has less direct cardiodepressant activity than flecainide or disopyramide.

Animals↗

PubMed2005

[Therapeutic strategies in inappropriate ICD therapy].

20-30% of ICD patients suffer from inappropriate ICD therapy due to misclassification of supraventricular tachycardia (SVT) as ventricular tachycardia. Inappropriate ICD therapies are not only painful for patients, but also proarrhythmogenic and can reduce device longevity due to battery depletion. Therapy of inappropriate ICD episodes is a puzzle of optimized ICD programming, antiarrhythmic therapy and radiofrequency (RF) ablation. Single-chamber ICD detection algorithms are effective in reducing inappropriate ICD therapy particularly due to sinus tachycardia or atrial fibrillation. Dual-chamber ICD detection algorithms were developed to improve specificity of SVT discrimination. However, large prospective, controlled trials showing superiority of dualchamber over single-chamber devices are lacking. It appears that patients with slow ventricular tachycardias, being at high risk for inappropriate ICD therapy, might benefit from dual-chamber ICD therapy. Concerning pharmacological therapy of inappropriate ICD episodes, the OPTIC study recently showed superiority of class III antiarrhythmics (sotalol and amiodarone) over beta-blockers. RF ablation of cavotricuspid isthmus is of proven benefit in ICD patients with inappropriate episodes due to typical flutter and should also be considered in atrial tachycardia. If patients with paroxysmal atrial fibrillation despite optimized antiarrhythmic medication will benefit from trigger elimination or substrate modification by RF ablation has still to be proven. In patients with inappropriate ICD episodes and drug-refractory chronic permanent atrial fibrillation, AV node ablation can effectively eliminate inappropriate ICD therapy, however, at the price of potential ventricular asynchrony and progression of heart failure due to right ventricular pacing. Thus, upgrading to biventricular ICD therapy should be considered in these patients.

Algorithms↗

PubMedDate not supplied

Incessant atrial tachycardias in a dog with tricuspid dysplasia. Clinical management and electrophysiology.

In a dog, tricuspid regurgitation due to congenital tricuspid dysplasia resulted in extreme right heart enlargement and right heart failure. Incessant supraventricular tachycardias were present, requiring the intravenous administration of verapamil to reduce the ventricular rate. Oral therapy using a combination of verapamil and quinidine was partially effective in controlling the ventricular rate during the following week. At that time, electrophysiologic studies were performed. They revealed that a succession of several atrial tachycardias with different cycle lengths, including one episode of atrial flutter, was present. Atrial activity was spanning the majority of the cycle length in all these arrhythmias. Epicardial mapping was performed during the atrial flutter. This enabled the detection of a depolarization wave-front traveling counterclockwise from the dorsolateral right atrium toward the right appendage, following the tricuspid valve annulus. No areas of abnormal conduction were detected. Because programmed electric stimulation maneuvers could not be performed, definitive conclusions about the mechanism of the arrhythmia could not be drawn. The two most likely possibilities were circus movement using part of the dilated tricuspid valve annulus as an anatomic barrier or a leading circle type of re-entry.

Animals↗

PubMed1970

Value of diazepam ('Valium') in treatment of cardiac arrhythmias.

Diazepam did not alter the rate or rhythm in III patients with atrial fibrillation. In 3 out of 38 patients with atrial flutter the use of diazepam was followed by an increase in atrioventricular block. Diazepam restored sinus rhythm in I patient with atrial tachycardia (total 7 patients) and in I patient with ventricular tachycardia (total 8 patients). Experimentally in the dog diazepam raised the electrically-induced ventricular tachycardia threshold significantly. Pretreatment with diazepam did not alter significantly the dose of strophanthidin K required to induce ventricular tachycardia in the dog. The value of diazepam as a cardiac anti-arrhythmic agent should be further assessed in a controlled clinical trial, especially in patients with acute myocardial infarction.

Aged↗

PubMed1989

Analysis of the characteristics of the flow velocity waveforms in left atrial small arteries and veins in the dog.

To clarify the characteristics of the phasic blood velocity pattern in small arteries and veins on the left atrial surface, we used our newly developed fiber-optic laser Doppler velocimeter. We intended particularly to examine the influence of atrial contraction and relaxation on velocity waveforms to obtain some insight into the nature of the mechanical force acting on the atrial intramyocardial vascular beds. In 14 anesthetized open-chest dogs, the left atrial appendage was gently displaced to expose small branches of the artery and vein. Vessels with an outer diameter of about 150-500 microns were chosen for the measurements because their walls are transparent to laser light. The fiber tip (velocity sensor) was fixed on the vessel surface with a drop of cyanoacrylate when good-quality Doppler signals were consistently observed. Additional experiments with three dogs were performed to observe the blood velocities in the atrial artery and vein during arrhythmia. The blood velocity waveform in the artery was similar to the pattern of aortic pressure during ventricular ejection (peak velocity, 18.8 +/- 7.8 cm/sec) but was characterized by a pronounced dip during atrial contraction. The temporal coincidence between the dip formation and atrial contraction was confirmed during atrial flutter with an atrioventricular block. After isoproterenol administration (2 micrograms i.v.), the acceleration rate of the forward flow velocity increased by 176% (p less than 0.05), and reverse flow appeared during atrial contraction in five cases out of eight (p = 0.013). The blood flow velocity in atrial small veins, on the other hand, was predominant during atrial contraction (peak velocity, 15.6 +/- 5.8 cm/sec). Isoproterenol increased the acceleration rate of this forward flow velocity by 121% (p less than 0.01). Nitroglycerin did not change the blood velocity waveform significantly in atrial arteries or in veins. The phase opposition between arterial inflow into and venous outflow from the atrial myocardium indicates that a large portion of the coronary inflow to the atrial myocardium may be stored due to the presence of atrial myocardial vascular capacitance. We conclude that atrial myocardial contraction impedes atrial inflow and promotes venous outflow from atrial capacitance vessels.

Animals↗

PubMed1990

Short-term control of supraventricular tachycardia with verapamil infusion and calcium pretreatment.

Nineteen consecutive patients with atrial fibrillation/flutter or other types of supraventricular tachycardia were given intravenous (IV) calcium salts (1 g) followed by verapamil infusion at a rate of 1 mg/min. Successful treatment was defined as control of ventricular response to less than or equal to 100 beats per minute (bpm) or conversion to sinus mechanism in patients with atrial arrhythmias: 11 patients had atrial fibrillation; three had atrial flutter; four had reentrant supraventricular tachycardias (SVT); and one had paroxysmal SVT. Therapy was successful in all patients. The mean dose of verapamil required to achieve desired outcome was 20 mg. Heart rate showed no significant change as a result of calcium pretreatment (160 bpm v 151 bpm). However, heart rate was significantly decreased, to 95 bpm, after treatment with verapamil. Blood pressure showed no change from baseline with either calcium or verapamil therapy. Verapamil infusion following IV calcium successfully treats atrial fibrillation/flutter or SVTs without depressing systemic blood pressure.

Aged↗

PubMed1995

[High frequency current catheter ablation in treatment of supraventricular and atrioventricular tachycardia].

Radiofrequency catheter ablation has been established as a first line therapy for the curative treatment of patients with atrioventricular nodal reentrant tachycardia and atrioventricular tachycardia encompassing accessory pathways as well as for ablation of the "normal" AV-junction. For these indications, the success rates exceed 90%. Acute complications during ablation of accessory pathway and ablation of the "normal" AV-junction occur in approximately 2-5% of patients treated. The incidence of complications during modification of the atrioventricular node to cure AV-nodal reentrant tachycardias clearly depends on the ablation technique used. The anterior approach with ablation of the so-called "fast pathway" carries a significantly higher risk of complete AV-block when compared to the inferior approach (so-called "slow pathway ablation") (approximately 4-8% vs. 2%). Arrhythmia recurrence after successful ablation of the "normal" AV-junction occurs only rarely, while the recurrence rate after modification of the AV-node or ablation of accessory pathway is approximately 10% during long-term follow-up. Recently, it has been shown that other, rare types of supraventricular tachycardia (sinus-atrial reentrant tachycardia, ectopic atrial tachycardia, human type I atrial flutter) can also be successfully ablated using radiofrequency current. In addition, first clinical results indicate that modification of anterograde AV-nodal conduction properties in patients with atrial fibrillation and fast ventricular rate by radiofrequency application to postero- and midseptal sites might be a useful therapeutic tool to slow ventricular rate. Because of the high success-rate and the relative low incidence of severe procedure related complications, the indications of radiofrequency ablation procedures for the treatment of supraventricular tachycardias will be extended in the future. In addition, it might be reasonable to expect that during the next years, all types of supraventricular tachycardia, except atrial fibrillation, can be targeted and cured by radiofrequency ablation in the majority of cases.

Atrioventricular Node↗

PubMed1993

Management of perioperative dysrhythmias.

This paper reviews cardiac dysrhythmias occurring in the perioperative period. Electrocardiography was the first application of electronic monitoring to anesthesia care. The detection of dysrhythmias remains the most important use of this technology today. While the description of dysrhythmias dates back to the early 1900's, the first large series was reported in 1936. Early descriptions of the kinds seen and the predisposing factors have changed little in the past 50 years. Several factors tend to emerge when one evaluates perioperative dysrhythmias. These are the anesthetic given, the site of surgery, abnormalities of blood gases or electrolytes, tracheal intubation, reflexes such as vagal slowing and the oculocardiac reflex, stimulation of the central nervous system the presence of pre-existing heart disease, and the use of intracardiac devices. In the evaluation of cardiac dysrhythmias several facts need to be determined. The most important is to determine if there is an underlying complication of anesthesia and surgery which may explain the dysrhythmia. In addition, one needs to evaluate the heart rate, the regularity, the number of P waves per QRS, and the configurations of the QRS. The anesthesiologist needs to determine whether the rhythm is dangerous to the patient and whether it requires treatment. The two major abnormalities of sinus rhythm are sinus bradycardia and the sinus tachycardia. Sinus bradycardia can be due to hypoxia, vagal stimulation, drug effects, a high sympathetic block or an acute myocardial infarction. Sinus tachycardia can be due pain, light anesthesia, hypovolemia, sepsis, hypoxia, hypercapnia and drug effects. The major atrial dysrhythmias are paroxysmal atrial tachycardia, atrial fibrillation and atrial flutter. Each require treatment if perfusion is impaired or if the heart rate is persistently elevated. The new agents esmolol and adenosine are particularly useful in managing atrial dysrhythmias. The major ventricular dysrhythmias are ventricular premature contractions, ventricular tachycardia and ventricular fibrillation. The later two demand emergency management with DC cardioversion when perfusion is impaired. The major abnormality of conduction is complete heart block which usually requires emergency treatment in the perioperative period. Prompt evaluation and management of perioperative dysrhythmias reduce anesthetic morbidity and mortality.

Arrhythmias, Cardiac↗

PubMed1976

[Atrial flutter with an audible atrial sound (author's transl)].

In a case of rheumatic valve disease atrial sounds could be heard and recorded on the phonocardiogram during atrial flutter at a rate of 260/min and an atrioventricular block of 3:1 and 5:1. The atrial flutter sounds were also recorded in the apex-cardiogram and as a slight but rapid motion of the anterior mitral valve leaflet in the echocardiogram. These atrial sounds were recorded both in systole and diastole and disappeared after cardiac failure had been treated and sinus rhythm restored. This case and 19 others reported in the medical literature indicate that for atrial sounds to become audible requires high-grade atrioventricular block and increased atrial contractions with increased ventricular filling. The sounds have been proven to originate in the atrium, the characteristics of the sound being similar to those of an opening snap.

Atrial Flutter↗

PubMed1979

[Rapid atrial stimulation in the treatment of atrial flutter (author's transl)].

Study on 35 patients suffering from atrial flutter, in which rapid atrial stimulation was made 40 times. Stimulation-catheters were introduced only by control of the intracardiac ecg without x-ray control. Sinus rhythm was restored in 31 cases, in 17 cases intermediate atrial fibrillation of varying length of duration. In 5 cases atrial fibrillation with normofrequent ventricular action was achieved. Appreciable complications were not seen. Essential advantages of the rapid atrial stimulation are the additional diagnostic information by the intracardiac ecg, the dispensable narcosis, the independence of a simultaneous medicamentous treatment, and the use in cases of sick sinus syndrome, too.

Adult↗

PubMed2006

The diagnostic utility of N-terminal pro-B-type natriuretic peptide for the detection of major structural heart disease in patients with atrial fibrillation.

AIMS: To assess the role of N-terminal pro-B-type natriuretic peptide (NT-proBNP) in the diagnosis of major structural heart disease (MSHD) in patients with atrial fibrillation (AF) compared with those with sinus rhythm (SR) using receiver operator characteristic (ROC) analysis. NT-proBNP is elevated in MSHD and heart failure (HF). AF, a common finding in HF and MSHD, is also associated with raised plasma NT-proBNP. As a result, the utility of NT-proBNP for predicting MSHD may be reduced. METHODS AND RESULTS: One thousand four hundred and seventy-six patients underwent assessment at a single centre, performed without the knowledge of NT-proBNP levels. MSHD included left ventricular (LV) systolic and diastolic dysfunctions, left-sided valvular disease, right heart disease (including pulmonary hypertension) and severe LV hypertrophy. One hundred and fifty-five patients were excluded due to renal impairment, atrial flutter, or a pacemaker. Seven hundred and ninety-three patients were diagnosed with MSHD. Median NT-proBNP concentrations for patients with MSHD were 960 (IQR 359-2625) pg/mL and 2491 (1443-4368) pg/mL for SR (n = 591) and AF (n = 202), respectively (P < 0.001). Patients without MSHD had NT-proBNP levels of 179 (90-401) pg/mL and 1000 (659-1760) pg/mL for SR (n = 454) and AF (n = 74), respectively (P < 0.001). The area under the ROC curve for NT-proBNP to detect MSHD was 0.79 for SR (95% CI 0.77-0.82) and 0.78 for AF (95% CI 0.72-0.84). NT-proBNP cut-off levels necessary to achieve a 1 in 100 false negative rate were 27.5 (7.5-30.5) pg/ml and 524 (253-662) pg/ml for SR and AF, respectively. CONCLUSION: NT-proBNP performs as well in patients with SR as in those with AF. However, significantly higher cut-off levels are required for patients with AF to achieve similar levels of diagnostic specificity.

Aged↗

PubMed1975

Electrophysiology and pharmacology of cardiac arrhythmias. VI. Cardiac effects of verapamil.

It is clear from clinical and experimental data that have been reported thus far that verapamil is highly effective in the therapy of cardiac arrhythmias, and that it acts by a different mechanism than most of the commonly used antiarrhythmic drugs. The available clinical data indicate that on intravenous administration verapamil is as good as and perhaps superior to quinidine, procainamide and propranolol for the therapy of many atrial arrhythmias. Unfortunately the extent to which it is useful as longterm prophylaxis has not yet been reported, nor has its toxicity during protracted oral administration. The effects of verapamil on cardiac action potentials clearly indicate that it modifies the slow response to a much greater extent than the fast response. Studies of cardiac tissues from diseased human atria have indicated that slow response action potentials occur frequently. It is possible that such action potentials are responsible for the reentrant and automatic arrhythmias which occur in association with clinical cardiac disease. Whether the efficacy of verapamil in the therapy of atrial arrhythmias is primarily due to abolishing slow response activity in diseased atrial tissues or to suppression of propagation through the atrioventricular node is uncertain. However, it is likely that the therapeutic action of the drug may result from altered propagation of an arrhythmia through the atrioventricular junction as well as from the effects of the drug on diseased atrial and ventricular tissues.

Action Potentials↗

PubMed2006

Efficacy and safety of ibutilide for the conversion of monomorphic atrial tachycardia.

BACKGROUND: Ibutilide is a class III antiarrhythmic drug, frequently used for conversion of atrial fibrillation and flutter. We studied the efficacy of ibutilide for acute conversion of monomorphic atrial tachycardia (monoAT) in a prospective, open label study in the intensive care unit of a cardiological clinic. METHODS: We examined 49 episodes of monoAT in 38 patients (19 men/19 women). Thirty-three patients (87%) suffered from structural heart disease. Twenty-three episodes occurred while on antiarrhythmic therapy with class I or III drugs. Patients with prolonged QT interval (except for patients with pretreatment with class III drugs), hypokalemia, left ventricular failure, and recent myocardial infarction were excluded. All patients received one or two doses of 1 mg ibutilide fumarate under continuous rhythm monitoring. RESULTS: Conversion to sinus rhythm occurred in 19 episodes (38.8%), in 6 episodes (12.2%) after the first dose. Conversion rate was significantly higher in patients with a short history of symptoms (66.6% vs 28.6%; P < 0.05), of documented arrhythmia (0.13 (0/5.7) vs 2.6 (0.38/23.5) months, median (interquartile range); P < 0.03), higher atrial rate (272 +/- 49 vs 207 +/- 36 beats/min (means +/- SD); P < 0.004), or without preexisting antiarrhythmic therapy (53.8% vs 21.7%; P < 0.02). No differences in conversion rates were found regarding gender, age, body mass index, left ventricular function, left atrial diameter, or underlying disease. In three episodes torsade de pointes occurred after ibutilide (6.1%), requiring defibrillation in two cases (4.1%). CONCLUSIONS: Ibutilide can be used for conversion of monoAT with a similar efficacy as for atrial fibrillation, but with a considerably lower efficacy compared to typical atrial flutter.

Anti-Arrhythmia Agents↗

PubMed1997

Role of adenosine in the diagnosis and treatment of tachyarrhythmias in pediatric patients.

Tachyarrhythmias are common rhythm disturbances in infants and children. Despite the availability of diagnostic criteria arrhythmias are sometimes commonly misdiagnosed. Recent reports suggest that an endogenous purine nucleoside, adenosine, has a diagnostic effect in narrow QRS complex tachycardias, in addition to terminating supraventricular tachycardia involving the atrioventricular node. This report reviews the authors' experience with the use of adenosine for diagnosis of narrow and wide complex tachyarrhythmias in children. Adenosine was administered to 43 patients with several types of tachyarrhythmias (mean age, 8.3 +/- 5.24 years). Nineteen patients had structural or acquired heart disease. Of the 43 patients there were 28 (65%) several different types of narrow QRS complex tachycardia and 14 (33%) ventricular arrhythmias. One patient (2%) had long QT. Adenosine terminated supraventricular tachycardia, in 11 of 12 patients (92%), ventricular tachycardia in five of eight patients (63%), and transiently terminated premature ventricular contractions in two of six patients (33%). The diagnostic ability of adenosine was perfect in eight supraventricular tachycardia. In these eight cases the tachycardia mechanism was unclear before the administration of adenosine, which demonstrated three cases of sinus tachycardia, three of atrial flutter, one of atrial fibrillation and one of atrial fibrilloflutter. Confirmation of the primary diagnosis by adenosine was perfect in five tachyarrhythmias including three cases of atrial flutter, one of atrial fibrillation and one of ectopic atrial tachycardia. The average effective dose of adenosine was 212 micrograms/kg (range, 100-400 micrograms/kg). There were no serious side-effects except transient dyspnea, chest pain and flushing. These findings demonstrate adenosine to be helpful and safe in the diagnosis of tachyarrhythmias.

Adenosine↗