Atrial Tachycardia Mimicking Atrioventricular Nodal Reentry Tachycardia

Background

The term supraventricular tachycardia (SVT) is used to describe tachydysrhythmias that require atrial or atrioventricular nodal tissue for their initiation and maintenance. SVT can be used to describe atrioventricular nodal reentry tachycardia, atrioventricular reentry tachycardia, and atrial tachycardia (AT). AT is the least common of these SVT subtypes, accounting for only 10% of cases. Although the suggested initial management of each SVT subtype is different, they all can present with similar symptoms and electrocardiographic findings.

Objective

Discuss the pathophysiology, diagnosis, and treatment of AT as compared with other types of SVT.

Case Report

We report a 56-year-old woman with symptoms and electrocardiographic findings consistent with SVT. Although standard treatment with intravenous adenosine failed to convert the SVT, it revealed AT as the cause of the tachydysrhythmia. The AT was successfully terminated with beta-blockade and the patient eventually underwent successful radioablation of three separate AT foci.

Conclusions

AT frequently mimics other more common forms of SVT. AT might be recognized only when standard treatment of SVT has failed. Identification of AT in this setting is crucial to allow for more definitive therapy.     

Occurrence of Atrial Fibrillation in Patients With Paroxysmal Supraventricular Tachycardia Due to Atrioventricular Nodal Reentry

The occurrence of atrial fibrillation in patients with paroxysmal supraventricular tachycardia (PSVT) has been well documented when PSVT is secondary to atrioventricular reentry, but not when PSVT is secondary to atrioventricular nodal reentry (AVNRT). Seventeen patients with AVNRT were followed using transtelephonic electrocardiogram monitoring to document symptomatic tachycardias. The median length of telephone monitor surveillance was 357 days. Fifteen of 17 patients transmitted electrocardiograms that showed PSVT. Three of 17 patients (18%) transmitted electrocardiograms that showed atrial fibrillation. A transition from PSVT into atrial fibrillation was not recorded, but all three did have PSVT recorded on other days of follow-up. We report the occurrence of atrial fibrillation in patients with AVNRT and that its incidence is higher than expected for the general population.     

Recurrent Ventricular Tachycardia Induced by an Atrial Synchronous Ventricular-Inhibited Pacemaker

Atrial synchronous pacemakers have been known to cause a variety of cardiac arrhythmias. Of particular concern are those arrhythmias invoiv ing a pacemaker stimuius occurring on a T wave, because these may lead to ventricuiar tachycardia. The Medtronic 2409 ASVIP pacemaker is an atrial synchronous pacemaker with several features de signed to decrease the likelihood of such arrhythmias. We report a patient in whom a normally func tioning Medtronic 2409 ASVIP pacemaker, despite these features, induced recurrent ventricular tachycardia. Conditions which predisposed this patient to pacemaker-induced re-entrant arrhythmias are discussed. [PACE, Vol. 5, July-August, 1982]     

Surgical Therapy for Sinoatrial Reentrant Tachycardia

Sinoatrial reentry is an uncommon cause of paroxysmal supraventricular tachycardia. This paper presents a case of supra ventricular tachycardia, refractory to medical therapy, in which the sinus node formed part or all of the reentrant circuit. The mechanism of the arrhythmia was confirmed by catheter mapping during electrophysiological study and by intraoperative epicardial mapping. Cryosurgical ablation of the right atrium in the region of the sinus node has led to cure of her arrhythmia and emergence of a stable ectopic atrial pacemaker rhythm.     

阵发性室上性心动过速并发阵发性房颤危险因素的临床研究

目的:筛选阵发性室上性心动过速(PSVT)患者中并发房颤的临床危险因素。了解PSVT患者中房颤的患病率及PSVT患者房颤发生的可能机制。方法:回顾研究经电生理检查证实为PSVT的患者共630例,其中依据临床记录同时有房颤发作的患者编为房颤组,其余无临床房颤发作的患者为对照组。制订调查表格并详细记录患者人口学资料、临床疾病相关资料、心脏超声检查结果、24h动态心电图结果、电生理检查中确定的PSVT折返机制、旁道数目等资料。利用SPSS进行t检验、χ2检验及Logistic回归分析PSVT患者并发房颤的危险因素。结果:630例(年龄13~79岁,平均年龄44.2±14.3岁男性326人,女性304例)中电生理检查房室结折返性心动过速256例(均为慢-快型),房室折返性心动过速374例,单因素分析表明男性、左房内径大及术前频发房性早搏(在AVRT亚组心电图表现为显性预激)为PSVT患者并发房颤的临床危险因素,多因素分析证明性别为PSVT患者并发房颤的独立临床危险因素。结论:PSVT并发房颤的患者常有一定的临床特征:男性居多,左房内径相对较大。     

Atrial Tachycardia Facilitating Initiation of Ventricular Tachycardia

A 17-year-old male was studied because of clinically documented tachycardias showing narrow and wide QRS complexes. He was found to suffer from an atrial and a ventricular tachycardia. It was demonstrated that initiation of ventricular tachycardia occurred on reaching a critical ventricular rate during atrial tachycardia. Our study illustrates the value of electrophysiological studies in patients suspected of suffering from double or multiple tachycardias. It also shows that the occurrence of one type of tachycardia may be critically related to another type of tachycardia.     

Surgery for Atrial Tachycardia

GUIRAUDON, G.M., ET AL.: Surgery for Atrial Tachycardia. Atrial flutter is associated with a macro-reentrant loop including an area of slow conduction cryoablation of which prevents atrial flutter to occur. Three patients underwent such intervention. Atrial fibrillation is associated with multiple reentrant circuits (leading circle of Allessie) that requires a critical surface area to perpetuate. We have designed an operation, the corridor operation, which isolate the sinus node and the AV node within a small segment of atrial tissue, to restore the chronotropic function of the sinus node. Nine patients underwent the corridor operation at our institution. There were eight men and one woman. Five had incessant atrial fibrillation and four paroxysmal. One patient had associated mitral valve stenosis and one cardiomyopathy. There were no perioperative complications. Six patients had normal sinus node function postoperatively including all the four patients with documented normal sinus node function preoperatively. Three patients required implantation of an AAI pacemaker. Two patients had recurrence of atrial fibrillation within the corridor. Our experience suggests that the corridor operation should be restricted to patients with documented good sinus node function and without structural heart disease. Our experience with five patients with paroxysmal sinus node tachycardia has been disappointing. Only one patient had long-term success although better series have been published.     

AV Node Reentry Tachycardia in Infants

The purpose of this study was to determine the frequency of atrioventricular (AV) node reentry tachycardia in infants undergoing transesophageal electrophysiological study for paroxysmal tachycardia. The records of all 52 infants < 1-year-old with structurally normal hearts who underwent transesophageal study for paroxysmal tachycardia over a 3-year period were reviewed. Those with a diagnosis of AV node reentry tachycardia underwent complete data review, and follow-up of > 12 months was obtained. Six of 52 infants had a diagnosis of the common type of AV node reentry tachycardia. Tachycardia was diagnosed at a mean age of 2.1 months (range 1 day to 10 months), and 3 of 6 underwent transesophageal study within the first month. Although no patient had structural heart disease, three patients had significant noncardiac disease. Follow-up of 15–38 months (mean 24 ± 7.8) revealed recurrences in 2 of 6 patients. The mean tachycardia cycle length was 240 ms (range 200–310 ms), and the transesophageal ventriculoatrial intervals ranged from < 30 to 55 ms. All patients had an inducible reentrant tachycardia with a ventriculoatrial interval that remained constant even when tachycardia cycle length increased following verapamil or adenosine administration, or decreased following isoproterenol infusion. Five of 6 had evidence for discontinuous AV node conduction curves. In our patients the substrate for AV node reentry tachycardia was present early in life, and AV node reentry tachycardia can be a clinical problem even in the newborn period.     

Prevention of Atrial Arrhythmias during DDD Pacing by Atrial Overdrive

We evaluated the effect of atrial overdrive on the incidence of atrial arrhythmias (AA) in 22 patients (67 ± 9 years. 7 women, 15 men) with Chorus 6234 DDD pacemakers. Atrial overdrive was defined as a programmed paced rate 10 ppm faster than the mean ventricular rate stored for the last 24-hour period in the pacemaker memory. The protocol consisted of three phases of 1 month each. Phase I: observation after discontinuation of antiarrhythmic therapy. Phase II: arrhythmia analysis using the pacemaker memory after programming the lower rate to 55 ppm. The fallback function and histogram data were used to document the number and maximal duration of AA episodes as well as the total AA time in a month. Phase III: atrial overdrive. The mean ventricular heart rate was 65 ± 4 beats/min before atrial overdrive versus 75 ± 5 with atrial overdrive (P = 0.02). At the end of phase II, all patients presented with AA episodes (mean number per patient: 42 ± 78 in one month). In phase III (with atrial overdrive), 14 (64.6%) patients had no recorded AA (group A). In the other eight patients with persistent AA episodes in phase III (group B), there was a significant reduction in the number of AA episodes (90 ± 106 in phase II vs 38 ± 87 in phase III; P = 0.01), their total duration (166 ± 115 in phase II vs 92 ± 134 hours in phase HI; P = 0.03) and their maximal duration (121 ± 103 in phase II vs 85 ± 89 min; P = 0.04). Our short-term data suggest tliat atrial overdrive prevents or reduces A A episodes and demonstrate the feasibility and need of long-term studies to determine whether this benefit is sustained.     

Provocation of Atrioventricular Reentry Tachycardia: A Paradoxical Effect of Adenosine

Adenosine has been used to diagnose latent preexcitation in patients with the Wolff-Parkinson-White syndrome. A case is reported in which intermittent preexcitation had been previously observed, however only retrograde accessory pathway conduction was documented at the time of invasive eiectrophysiological study, Administration of intravenous adenosine during sinus rhythm resulted in provocation of orthodromic atrioventricular reentry tachycardia.     

Atrial and Ventricular Pressures in Atrial Flutter

The hemodynamic effects of atrial flutter (AF) are unknown. The purpose of the present study was to investigate the changes in atrial and ventricular pressures after induction of AF. In 23 patients with paroxysmal AF (age 59 ± 9 years), a hemodynamic study was performed both during sinus rhythm and after induction of the tachyarrhythmia. During AF, 13 patients showed a fixed 2:1 AV conduction and 10 patients showed variable conduction. Mean right and left atrial pressures increased (P < 0.001) and right and left ventricular end-diastolic pressures decreased (P < 0.001) after induction of AF. Roth the increase in mean atrial pressures and the decrease in ventricular end-diastolic pressures were present either in the patients with fixed 2:1 AV (heart rate: 133 ± 15 beats/min) or in those with variable conduction (heart rate 96 ± 15 beats/min), but were more marked in the former. AF produces an impairment of atrial function, as evidenced by the increase in mean atrial pressures and reduction in ventricular end-diastolic pressures in the absence of an elevated heart rate. The mechanisms responsible for the increase in mean atrial pressures are unknown; however, atrial contractions against closed AV valves seem to play an important role.     

Recipient to Donor Conduction of Atrial Tachycardia Following Orthotopic Heart Transplantation

We report a case of atrial tachycardia in a 60-year-old male 8 years postorthotopic heart transplantation. At electrophysiology study, the clinical rhythm was found to arise from the remnant of the recipient atrium and was successfully terminated by delivery of radiofrequencv energy. Surgical scars formed at the anastomosis of the recipient and donor atrium during the time of orthotopic heart transplantation are thought to electrically isolate the two areas. Although rarely recognized, dysrhythmias originating from the recipient atrial remnant may occur more often than previously thought.     

Giant Left Atrial Thrombus Associated with Ablation for Atrial Tachycardia

We report a very rare case of giant left atrial thrombus (size: 7.2 × 4.5 mm²) associated with radiofrequency catheter ablation for atrial tachycardia in a 72-year-old man. After 4 weeks of anticoagulation with warfarin, a repeat echocardiogram demonstrated partial resolution of the thrombus (size: 4.5 × 2.6 mm²) without systemic embolization.     

Role of Invasive Electrophysiologic Studies in the Evaluation and Treatment of Supraventricular Tachycardia

Electrophysiologic studies have provided new insights into the mechanisms responsible for supraventricular arrhythmias and have enabled investigators to evaluate with precision the acute effects of pharmacologic, physiologic, electrical, and surgical interventions. Not all patients with supraventricular arrhythmias require invasive studies, however, since empiric drug trials will often be adequate for management. At present, the clinical indications for study include the following: (1) for diagnosis of tachycardia mechanism when scalar ECG analysis is uncertain; (2) for assessment of risk of future life-threatening arrhythmia; and (3) as a rapid means of assessing future therapy when sporadic arrhythmias are likely to be poorly tolerated. Innovations that include surgical and catheter ablations of tachycardia pathways and antitachycardia pacing devices hold great promise and in the future, will provide nonpharmacologic options for patients poorly controlled by or intolerant of drug therapy.     

Electrophysiological Features of Atrial Tachycardia Arising from the Atrioventricular Annulus

MATSUOKA, K., et al. : Electrophysiological Features of Atrial Tachycardia Arising from the Atrioven-tricular Annulus. Atrial tachycardia (AT) arises from various sites in the atrium and the mechanisms are nonuniform. McGuire et al. reported that the cells around the atrioventricular annuli resembled nodal cells in their cellular electrophysiology. The purpose of this study was to delineate the electrophysiological features of AT arising from the atrioventricular (AV) annulus (AVAT). The study included five patients with six AVATs that were abolished by the radiofrequency energy delivery. The location of the AV annuli was defined by using the AV ratio of the local electrograms and the amplitude of the ventricular electrograms, in addition to the anatomic findings under fluoroscopic guidance. The tachycardia cycle lengths were  403 ± 117 ms  . An AV ratio of the electrograms at the successful ablation sites was  0.4 ± 0.4  at the tricuspid annulus and  1.5 ± 0.3  at the mitral annulus. Small doses (  mean 3.2 ± 1.8 mg  ) of adenosine triphosphate could terminate all the tachycardia episodes for five of the ATs without the development of AV nodal conduction block. The successful ablation sites were located at the right mid-septum in 1 AT, right posteroseptum in 2 ATs, right posterolateral region in 1 AT, and left anteroseptum in 2 ATs. These findings suggest that the cells with nodal-type action potentials around both annuli might play an important role in the genesis of AVAT.     

Incessant Ectopic Atrial Tachycardia and Sudden Death

A patient with refractory and incessant ectopic atrial tachycardia (IEAT) is reported in whom it was possible to document, during EGG (Holter) the occurrence of aborted sudden death by spontaneous ventricular fibrillation (VF). Following the second of two attempts at surgical ablation of the origin of the IEAT, the patient has been asymptomatic without antiarrhythmic drugs and in sustained sinus rhythm for 24 months. Although we cannot exclude the residual action of amiodarone and flecainide (proarrhythmia) or the residual peripartum cardiomyopathy it is probable that the observed VF was a true complication of a cardiomyopathy induced by a chronically increased heart rate (HR). Although unclear, this VF might be considered as a form of adrenergic-dependent long QT syndrome due to early afterdepolarization in the presence of predisposing myocardial conditions.     

Atrial Antitachycardia Pacing in Patients with Supraventricular Tachycardia: Clinical Experience with the Intertach Pacemaker

MCCOMB, J.M., ET AL.: Atrial Antitachycardia Pacing in Patients with Supraventricular Tachycardia: Clinical Experience with the Intertach Pacemaker. During a 3-year period, 22 patients with recurrent supraventricular tachycardia have been treated with antitachycardia pacemakers [Intermedics Intertach, 262–12, n = 17, and Intertach II, 262–16, n = 5). Eighty-two percent were female, the mean age was 44 ± 14 years; 86% had atrioventricular node reentrant tachycardia. Symptoms had occurred over 11.8 ± 7.1 years, with 3.6 hospital admissions per patient, despite 4.7 ± 2.1 antiarrhythmic drugs. Following pacemaker implantation, during a follow-up of 14.8 ± 11.5 months, only two patients have been readmitted to a hospital because of supraventricular tachycardia (mean 0.1 per patient). One patient is taking an antiarrhythmic agent, and four are taking beta adrenergic blocking agents. Thus, 23% are taking cardioactive drugs (it was anticipated that two patients would continue on drugs after pacemaker implantation). There have been no serious complications. Atrial antitachycardia is thus an effective therapy in carefully selected patients with recurrent supraventricular tachycardia, reducing hospital admissions for supraventricular tachycardia and reducing the need for antiarrhythmic drugs.