Form Of Paroxysmal Supraventricular Tachycardia Research Articles

The Upper Common Pathway in Atrioventricular Nodal Reentrant Tachycardia: A Comprehensive Review of Evidence and Current Perspectives.

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common form of paroxysmal supraventricular tachycardia, and its diagnostic and therapeutic approaches have been well-established. Traditionally, AVNRT is understood to be an intranodal reentry having two bystander pathways; the upper common pathway (UCP) which connects to the atrium and the lower common pathway which connects to the ventricle. However, the existence of the UCP remains a subject of ongoing debate. The assertion of the UCP's presence is supported by electrophysiological evidence suggesting that the atrium is not essential for the perpetuation of AVNRT. Nonetheless, numerous anatomical studies have failed to identify any structure that could be conclusively designated as the UCP. The histological and electrophysiological characteristics of the slow and fast pathways, which are the core components of AVNRT, suggest the inclusion of atrial myocardium in the reentry circuit. While clear interpretation of these discrepancies remains elusive, potential explanations may be derived from existing evidence and recent research findings concerning the actual AVNRT circuit.

Clinical profile and electrophysiological characteristics of atypical atrioventricular nodal reentrant tachycardia: A decade's experience

ObjectiveTo assess the clinical features and inducibility characteristics of atypical atrioventricular nodal reentrant tachycardia (AVNRT) and compare it with typical AVNRT. BackgroundAVNRT is the commonest form of paroxysmal supraventricular tachycardia. The mechanism of AVNRT is very varied. Several classification systems evolved with better understanding but a simplified approach of classification into typical and atypical AVNRT is justifiable and clinically more relevant. In our study, we have assessed the epidemiological profile of atypical AVNRT in a single institute over 10 years and analysed pertinent electrophysiological characteristics. MethodIn this retrospective observational single center study we analysed data of all AVNRT cases from January 2011 to June 2021. In our study we classified atypical AVNRT and typical AVNRT based on the HA interval; HA≤70 ms in the His bundle region during tachycardia was considered as typical AVNRT. Other parameters were also analysed during tachycardia, such as: induction by atrial or ventricular pacing, AH/HA ratio, tachycardia cycle length and site of the earliest atrial activation. The demographic profile of the patients were also compared between 2 groups. ResultsAtypical AVNRT was found in 75/1431 patients (5.2%) of all cases of AVNRT. The age of patients with atypical AVNRT was 52.4 ± 15.2 years (range 9–82 years) while that for typical AVNRT it was 48.2 ± 15.7 years (2–89 years), p = 0.023. There was no gender difference. Atypical AVNRT was induced by only ventricular extrastimuli (VES) in 17/75 (22.6%) while in typical AVNRT this was seen in only 12/1356 patients (0.9%, p < 0.001). Induction of atypical AVNRT was seen by both atrial extrastimuli (AES) and VES in 17/75 patients (22.6%) while in typical AVNRT this was seen in 64/1356 patients (4.8%, p < 0.001). Atypical AVNRT was induced by only AES in 40/75 patients (53.3%) while in typical AVNRT this was seen in 1280/1356 patients (94.3%, p < 0.001). An AH >200 ms during tachycardia was seen in all patients with typical AVNRT and in only 31/75 patients (41.3%) of atypical AVNRT (p < 0.00001). An interesting finding in atypical AVNRT was the earliest atrial activation at the His bundle region in 10/75 (13.3%) patients. ConclusionAtypical AVNRT prevalence depends on the way it is classified; this was 5.2% of all AVNRT cases in our study. Typical AVNRT was seen more frequently in comparatively younger age group and was more often induced by AES. Atypical AVNRT was much more commonly induced by only VES compared to typical AVNRT. It was not so unusual in atypical AVNRT to find the earliest atrial activation in the His bundle region.

Dual atrioventricular nodal pathways: physiology, arrhythmic findings, and electrocardiographic manifestations

The atrioventricular (AV) node is an anatomically well-defined structure, conveniently housed in the triangle of Koch. There are two distinct atrial impulse approaches to the AV node, one of which (in the anterior portion of triangle of Koch) has a faster conduction, while the other one (in the posterior portion) has a slower conduction. However, it is not said that such a conductive duality translates into any arrhythmic phenomena. Actually, these arrhythmias are due to an imbalance of the two pathways electrophysiological properties, which does not always exist. In the presence of such an imbalance, the dual AV nodal physiology is, however, the substrate for various arrhythmias and curious electrocardiographic behaviors. Often the fast pathway is characterized by a relatively long refractory period. In contrast, the slow approach is often characterized by shorter refractoriness.The unbalanced refractoriness of the two nodal pathways constitutes the prerequisite for the most common form of paroxysmal supraventricular tachycardia: the AV nodal reentrant tachycardia (AVNRT). In subjects prone to this type of arrhythmia, during sinus rhythm, nodal conduction usually occurs from the anterior approach (fast pathway). However, a premature atrial beat may find this pathway refractory and cross the AV node through the posterior approach (slow pathway), resulting in a sudden prolongation of the AV conduction time ("jump"). This allows the impulse, once it reaches the common end, to excitate the fast pathway in a retrograde direction and to return backwards to the atrium, thus triggering a circus movement that can result in a "slow-fast" AVNRT. More rarely, an AVNRT can take place in an opposite direction of the reentrant impulse ("fast-slow" variety of AVNRT). A paroxysmal supraventricular tachycardia may seldom occur with a regularly alternating RR cycle, if the reentrant mechanism involves retrogradely an accessory AV pathway and, in anterograde direction, a fast and a slow AV nodal pathway, alternately. Among the mechanisms underlying the total RR irregularity during atrial fibrillation, there is probably also the possibility that the AV node may offer to the atrial impulses two distinct pathways to reach the His bundle. Not too rarely, a dual AV nodal physiology can occur during sinus rhythm, through unexpected and sudden changes in the AV conduction time, so that two distinct PR families can be observed. It is likely that the presence of dual AV nodal pathways can facilitate or promote a Wenckebach conduction mechanism at nodal site.

An unusual focal atrial tachycardia that simulates a common node reentrant tachycardia: A case report

Focal atrial tachycardia is a relatively uncommon paroxysmal supraventricular tachycardia. Although atrioventricular conduction is regularly 1:1 and the PR interval is often in the normal range, occasionally a 1:1 atrial tachycardia may have a short RP interval, especially when the heart rate is particularly high or the atrioventricular conduction is markedly increased. In these cases, it is necessary to differentiate focal atrial tachycardia from common atrioventricular nodal reentrant tachycardia , which is the most frequent form of paroxysmal supraventricular tachycardia. We describe a case of unusual focal atrial tachycardia with a short RP interval (&lt; 90 ms) in a patient with a marked AV first-degree block which simulates a typical atrioventricular nodal reentrant tachycardia.

Diagnostic Accuracy of Several Electrocardiographic Criteria for the Prediction of Atrioventricular Nodal Reentrant Tachycardia

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common form of paroxysmal supraventricular tachycardia (SVT) whose diagnosis can be strongly suspected based on the surface eletrocardiogram alone. The purpose of this study is to determine the diagnostic accuracy of several electrocardiographic (ECG) criteria for the prediction of AVNRT. Between November 2010 and January 2014, a total of 256 patients who underwent electrophysiological testing (EP) with regular, paroxysmal and narrow QRS complex tachycardia were prospectively enrolled. We classified the ECG recordings during tachycardia for the presence of the following criteria: a) classical ECG findings of pseudo S wave in inferior leads and/or pseudo r' wave in lead V1, b) notch in lead aVL, c) no retrograde P waves visible during tachycardia; d) pseudo r' wave in lead aVR, e) notch in lead D1, f) any deflection after 100ms of the QRS complex during tachycardia. On multivariate analysis, independent predictors of AVNRT diagnosis were female sex (OR 4.17; 95% CI [2.11-8.24]; p <0.001), age >60years (OR 3.53; 95% CI [1.25-9.96]; p=0.017) and the classical ECG criteria (OR 7.41; 95% CI [3.62-15.17]; p <0.001). Female, age >60years and the classical ECG criteria were the independent predictors of AVNRT diagnosis. Although several of the ECG criteria for AVNRT diagnosis showed acceptable sensitivities and specificities, they do not improve its accuracy.

A re-entry tachycardia triggered by the spontaneous interruption of an atrial tachycardia

The common atrioventricular nodal re-entry tachycardia is the most common form of paroxysmal supraventricular tachycardia. It starts frequently with a supraventricular ectopic beat that, on finding the fast pathway in refractory period, travels in the slow pathway as to appear as a prolongation of the PR interval on the ECG. In this study, we show a singular case of a common atrioventricular nodal re-entry tachycardia triggered by the spontaneous interruption of an atrial tachycardia.

Atrioventricular complete block occurring 12 years after successful ablation of slow-slow atrioventricular nodal reentrant tachycardia

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most frequent form of paroxysmal supraventricular tachycardia. Selective radiofrequency (RF) catheter ablation of the slow pathway is an ideal method for treatment of patients with AVNRT. Complete atrioventricular block is a rare but serious complication of RF ablation, and primarily occurs during or immediately after the procedure. We report on a 45-year-old woman who underwent successful ablation for symptomatic AVNRT at the age of 33. She presented with paroxysmal complete AV block, which developed twelve years after RF ablation of the slow pathway and a permanent DDD pacemaker was implanted. As seen in the case we report, complete AV block complicating RF ablation can occur years after the procedure.

Degeneration of atrioventricular nodal reentrant tachycardia into polymorphic ventricular tachycardia: a case report

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common form of paroxysmal supraventricular tachycardia and is usually treated successfully by radiofrequency catheter ablation. We report on a 38-year-old woman whose AVNRT attacks occasionally degenerated into polymorphic ventricular tachycardia (VT). The patient presented with a complaint of palpitations. The electrocardiogram was in sinus rhythm with a normal corrected QT interval. During Holter monitoring, narrow QRS complex tachycardia with a heart rate of 220 beats/min was noted at nighttime, that lasted for 90 minutes, during which two episodes of polymorphic VT were also seen. The diagnosis of AVNRT was confirmed on an electrophysiologic study and AVNRT was successfully treated by radiofrequency catheter ablation. The patient had no complaint during a follow-up of eight months, with no signs of arrhythmia on repeat Holter monitoring.

Posterior His Bundle Electrogram Location in a Patient With Atrioventricular Nodal Reentrant Tachycardia and Structurally Normal Heart

Atrioventricular (AV) nodal reentrant tachycardia is the most common form of paroxysmal supraventricular tachycardia in adults, and slow AV nodal pathway ablation has evolved into first-line therapy. Variations in conduction system anatomy are occasionally found at electrophysiological study and may make this ablation procedure very challenging. Here, we present the case of a 69-year-old man with a structurally normal heart and posterior displaced His bundle who underwent successful slow pathway ablation. Demonstration of the characteristic slow pathway recording and His bundle electrogram is strongly recommended prior to radiofrequency energy application in the posterior septal region.

Randomized Study of Propofol Effect On Electrophysiological Properties of the Atrioventricular Node in Patients with Nodal Reentrant Tachycardia

Atrioventricular nodal reentrant tachycardia (AVNRT) is probably the most common form of paroxysmal supraventricular tachycardia. Percutaneous catheter ablation is a technique to interrupt cardiac conduction pathways selectively. The anesthetist is challenged to provide a safe anesthetic which takes into account the electrophysiologist's requirements for minimal cardiac conduction interference. Propofol is an ideal drug. However, previous studies have shown that the infusion of propofol has sometimes been associated with bradyarrhythmias or conversion of arrhythmias to sinusal rhythm. The purpose of this report is to verify the interferences of propofol in the electrophysiological properties of the atrioventricular (AV) node conduction system in patients with AVNRT. Patients were randomly assigned to receive either a placebo or propofol at sedative doses. An electrophysiological study was performed consisting of measuring the anterograde (AERPFP) and retrograde effective refractory period of the fast (RERPFP) and the anterograde effective refractory period of the slow (AERPSP) AV nodal pathway. Reciprocating tachycardia was induced and the cycle length (CL) and atrial-His (AH), His-ventricular (HV), and ventriculoatrial (VA) intervals were measured. Propofol did not cause alteration (P > 0.05) in the AERPFP or RERPFP and the AERPSP AV nodal pathway. The AH, HV, and VA intervals were not affected. Sustained reciprocating tachycardia could be induced in the all patients. All slow pathways were successfully identified and ablated. Propofol has no effect on the electrophysiological properties of the AV node conduction system. It is thus a suitable anesthetic agent for use in patients undergoing ablative procedures.

The Response of Paroxysmal Supraventricular Tachycardia to Overdrive Atrial and Ventricular Pacing:

Standard electrophysiologic techniques generally allow discrimination among mechanisms of paroxysmal supraventricular tachycardia. The purpose of this study was to determine whether the response of paroxysmal supraventricular tachycardia to atrial and ventricular overdrive pacing can help determine the tachycardia mechanism. Fifty-three patients with paroxysmal supraventricular tachycardia were studied. Twenty-two patients had the typical form of atrioventricular (AV) junctional (nodal) reentry, 18 patients had orthodromic AV reentrant tachycardia, 10 patients had atrial tachycardia, and 3 patients had the atypical form of AV nodal reentrant tachycardia. After paroxysmal supraventricular tachycardia was induced, 15-beat trains were introduced in the high right atrium and right ventricular apex sequentially with cycle lengths beginning 10 msec shorter than the spontaneous tachycardia cycle length. The pacing cycle length was shortened in successive trains until a cycle of 200 msec was reached or until tachycardia was terminated. Several responses of paroxysmal supraventricular tachycardia to overdrive pacing were useful in distinguishing atrial tachycardia from other mechanisms of paroxysmal supraventricular tachycardia. During decremental atrial overdrive pacing, the curve relating the pacing cycle length to the VA interval on the first beat following the cessation of atrial pacing was flat or upsloping in patients with AV junctional reentry or AV reentrant tachycardia, but variable in patients with atrial tachycardia. AV reentry and AV junctional reentry could always be terminated by overdrive ventricular pacing whereas atrial tachycardia was terminated in only one of ten patients (P < 0.001). The curve relating the ventricular pacing cycle length to the VA interval on the first postpacing beat was flat or upsloping in patients with AV junctional reentry and AV reentry, but variable in patients with atrial tachycardia. The typical form of AV junctional reentry could occasionally be distinguished from other forms of paroxysmal supraventricular tachycardia by the shortening of the AH interval following tachycardia termination during constant rate atrial pacing. Atrial and ventricular overdrive pacing can rapidly and reliably distinguish atrial tachycardia from other mechanisms of paroxysmal supraventricular tachycardia and occasionally assist in the diagnosis of other tachycardia mechanisms. In particular, the ability to exclude atrial tachycardia as a potential mechanism for paroxysmal supraventricular tachycardia has important implications for the use of catheter ablation techniques to cure paroxysmal supraventricular tachycardia.

Modification of the Atrioventricular Node: A New Approach to the Treatment of Supraventricular Tachycardias

Atrioventricular nodal modification appears to be a relatively safe and effective treatment option for patients with refractory AV nodal reentrant tachycardia. Hopefully, the long-term results will be as encouraging as the initial experience. Newer surgical and catheter techniques, together with a better understanding of the mechanisms underlying AV nodal reentrant tachycardia, may lead to improved efficacy and safety. In the future, AV nodal modification may obviate the need for drug therapy in patients with symptomatic AV nodal reentrant tachycardia and be applied to the treatment of other supraventricular tachycardias.

Sustained symptomatic sinus node reentrant tachycardia: Incidence, clinical significance, electrophysiologic observations and the effects of antiarrhythmic agents

The clinical, electrocardiographic and electrophysiologic determinants and effects of antiarrhythmic agents on sustained sinus node reentrant tachycardia remain poorly defined. Of 65 consecutive men undergoing electrophysiologic studies for symptomatic paroxysmal supraventricular tachycardia over a 4 year period, 11 (16.9%), who ranged in age from 39 to 76 years, demonstrated sustained sinus node reentrant tachycardia. On the surface electrocardiogram, before electrophysiologic studies, the following diagnoses were considered in the 11 patients: sinus node reentrant tachycardia on the basis of an RP'/P'R ratio of greater than 1 and P wave configuration similar to that of sinus P waves (7 patients); atrioventricular (AV) nodal reentrant tachycardia on the basis of an RP'/P'R ratio of less than 1 (3 patients); and paroxysmal atrial tachycardia with AV block (1 patient). All 11 patients had a history of recurrent palpitation, 4 had syncope, 2 had dizzy spells and 9 had organic heart disease. Sustained sinus node reentrant tachycardia could be reproducibly induced in all 11 patients during atrial pacing or premature atrial stimulation, or both, over a wide echo zone. The tachycardia could be terminated by carotid sinus massage, atrial pacing and premature atrial stimulation. Characteristics of tachycardia included: high-low activation sequence; cycle lengths of 250 to 590 ms with wide fluctuations of 20 to 180 ms in individual patients; RP'/P'R ratio of greater than 1 in 8 (73%) of the 11 patients and a ratio of less than 1 in 3 (27%). Induction of sustained sinus node reentrant tachycardia was prevented by intravenous ouabain (0.01 mg/kg body weight) in two of two patients, by intravenous verapamil (10 mg) in two of two patients and by intravenous amiodarone (5 mg/kg body weight) in four of four patients. In contrast, intravenous propranolol (0.1 mg/kg body weight) did not affect induction of sustained sinus node reentrant tachycardia in two of two patients. It is concluded that sustained sinus node reentrant tachycardia, seen in 16.9% of the study patients with paroxysmal supraventricular tachycardia, is not as benign as previously believed; it is frequently associated with organic heart disease; it demonstrates wide variations in cycle length, unlike other forms of paroxysmal supraventricular tachycardia; it can masquerade as AV nodal reentrant tachycardia and paroxysmal atrial tachycardia with AV block on the surface electrocardiogram in 36% of patients; and it is responsive to intravenous administration of ouabain, verapamil or amiodarone.

The importance of electrophysiological studies of atrio-ventricular conduction for diagnostics of some forms of paroxysmal supraventricular tachycardia.

The importance of electrophysiological studies of atrio-ventricular conduction for diagnostics of some forms of paroxysmal supraventricular tachycardia.

Swallowing-Induced Supraventricular Tachycardia

A rare form of paroxysmal supraventricular tachycardia (SVT), associated with swallowing solid food, is described. Repeated triggering of the arrhythmia during esophagoscopy was produced by mechanical stimulation of the anterior esophageal wall, 30 cm from the incisors. Treatment with verapamil abolished this tachycardia. Esophagoscopic examination, the first of its kind in this setting, aided the investigation.