Dual Atrioventricular Nodal Research Articles

A stroke patient with an unusual electrocardiogram

We present a case of a 70 year old man with a history of paroxysmal atrial flutter who was admitted to the hospital with symptoms and imaging consistent with an acute stroke. Physical exam was notable for a pulse rate of 50 beats per minute and right sided facial droop with mild dysarthria. Admission ECG shows a junctional bradycardia with evidence of dual AV node physiology, rarely manifested in a retrograde fashion on a standard ECG. The patient likely experienced parasympathetic sinus node slowing in the setting of acute stroke. During post-stroke monitoring, the patient demonstrated return of sinus rhythm with chronotropic competence and he had no additional arrhythmia during admission.

Double Ventricular Response with Aberrant Conduction Leading to Ventricular Dysfunction.

Double ventricular response (DVR), where a single P wave results in two QRS complexes, is a rare presentation of dual AV node physiology. It has been associated with ventricular dysfunction in the setting of incessant tachycardia. We present the case of an otherwise healthy adolescent who had frequent DVR without tachycardia leading to left ventricular dysfunction. Slow pathway modification led to a significant reduction in ectopy and normalization of ventricular function. This highlights that DVR without tachycardia might lead to ventricular dysfunction in pediatric patients. Slow pathway modification with reduction of ectopy may be sufficient to restore ventricular function.

Dual atrioventricular nodal non-reentrant tachycardia: an often overlooked diagnosis.

Dual atrioventricular nodal non-reentrant tachycardia: an often overlooked diagnosis.

Occam's Razor: Two Arrhythmias in a Single Heart?

Occam's Razor: Two Arrhythmias in a Single Heart?

Dual Atrioventricular Nodal Non–Re-Entrant Tachycardia

A patient presented with symptoms of palpitations. Her standard 12-lead electrocardiogram captured 3 potential causes of her symptoms (premature atrial contractions, junctional rhythm, and narrow complex tachycardia). Further workup uncovered dual atrioventricular node physiology with 1:2 sinus conduction and resultant alternating QRS from a slow and fast conduction pathway. (Level of Difficulty: Intermediate.)

High-density electroanatomic activation mapping to guide slow pathway modification in patients with persistent left superior vena cava

Slow pathway (SP) mapping and modification can be challenging in patients with persistent left superior vena cava (PLSVC) due to anatomic variance of the Koch triangle (KT) and coronary sinus (CS) dilation. Studies using detailed 3-dimensional (3D) electroanatomic mapping (EAM) to investigate conduction characteristics and guide ablation targets in this condition are lacking. The purpose of this study was to describe a novel technique of SP mapping and ablation in sinus rhythm using 3D EAM in patients with PLSVC after validation in a cohort with normal CS anatomy. Seven patients with PLSVC and dual atrioventricular (AV) nodal physiology who underwent SP modification with the use of 3D EAM were included. Twenty-one normal heart patients with AV nodal reentrant tachycardias formed the validation group. High-resolution, ultra-high-density local activation timing mapping of the right atrial septum and proximal CS in sinus rhythm was performed. SP ablation targets were consistently identified by an area in the right atrial septum with the latest activation time and multicomponent atrial electrogram adjacent to a region with isochronal crowding (deceleration zone). In PLSVC patients, these targets were located at or within 1 cm of the midanterior CS ostium. Ablation in this area led to successful SP modification, reaching standard clinical endpoints with a median of 43 seconds of radiofrequency energy or 14 minutes of cryoablation without complications. High-resolution activation mapping of the KT in sinus rhythm can facilitate localization and safe SP ablation in patients with PLSVC.

Dual atrioventricular nodal non-reentrant tachycardia: Various atrioventricular conduction responses to atrioventricular simultaneous pacing.

Specific pacing methods to unmask the existence of the dual atrioventricular (AV) nodal pathway in patients with dual AV nodal non-reentrant tachycardia remain to be established. This study aimed to determine the electrophysiological characteristics of dual AV nodal non-reentrant tachycardia by its responses to specific pacing methods. Five patients diagnosed as having dual AV nodal non-reentrant tachycardia were retrospectively investigated. Atrial pacing could not induce the clinical tachycardia as continuous double firing in any of the 5 patients, but did induce sudden prolongation of the A-H interval as the linking phenomenon in 1 patient. A single atrial extrastimulation after sinus excitations was performed without interruption of double firing in 1 patient, and it induced the double ventricular response phenomenon within the limited range of the extrastimulus intervals. The pacing method of AV simultaneous basic pacing preceding atrial programmed extrastimulation did not allow interruptions of double firing during the basic drive trains and induced the double ventricular response phenomenon within the limited range of the extrastimulus intervals in all 5 patients, even in 1 patient without inducibility of the clinical tachycardia in the catheterization laboratory. The double ventricular response phenomenon within the limited range of the extrastimulus intervals may be based on the existence of the dual AV nodal pathway with concealed retrograde penetration. The AV simultaneous basic pacing preceding atrial programmed extrastimulation method consistently and reproducibly unmasked the existence of the dual AV nodal pathway as the double ventricular response phenomenon in patients with dual AV nodal non-reentrant tachycardia.

Case report: Dual atrioventricular nodal non-reentrant tachycardia with six types of ECG patterns leading to tachycardia-induced cardiomyopathy in a 51-year-old man

More than three types of ECG manifestations in one patient with dual atrioventricular nodal non-reentrant tachycardia (DAVNNT) are rare. We report a 51-year-old male patient with DAVNNT consisting of six types of ECG patterns leading to tachycardia-induced cardiomyopathy. After radiofrequency ablation of the slow pathway, DAVNNT was eliminated and cardiac function was restored.

Dual Atrioventricular Nodal Non-Reentrant Tachycardia Misdiagnosed as Rapid Atrial Fibrillation - The Role of Adenosine.

We report a case of a 56-year-old man diagnosed with non-ischemic cardiomyopathy in 2017 with progressive decline in left ventricular systolic function and frequent hospitalisations for heart failure in the context of a presumed atrial fibrillation with high ventricular rate. Electrocardiographic changes after adenosine administration raised the suspicion of dual atrioventricular nodal non-reentrant tachycardia, a diagnosis that was confirmed by electrophysiological study, making adenosine a potential diagnostic aid in such cases. The ablation of the slow pathway terminated the tachycardia and led to a marked improvement in symptomatology and echocardiographic parameters.

Radiofrequency Catheter Ablation for Pediatric Atrioventricular Nodal Reentrant Tachycardia: Impact of Age on Procedural Methods and Durable Success.

BackgroundCatheter‐based slow‐pathway modification (SPM) is the treatment of choice for symptomatic atrioventricular nodal reentrant tachycardia (AVNRT). We sought to investigate the interactions between patient age and procedural outcomes in pediatric patients undergoing catheter‐based SPM for AVNRT.Methods and ResultsA retrospective cohort study was performed, including consecutive patients undergoing acutely successful SPM for AVNRT from 2008 to 2017. Those with congenital heart disease, cardiomyopathy, and accessory pathways were excluded. Patients were stratified by age quartile at time of SPM. The primary outcome was AVNRT recurrence. A total of 512 patients underwent successful SPM for AVNRT. Age quartile 1 had 129 patients with a median age and weight of 8.9 years and 30.6 kg, respectively. Radiofrequency energy was used in 98% of cases. Follow‐up was available in 447 (87%) patients with a median duration of 0.8 years (interquartile range, 0.2–2.5 years). AVNRT recurred in 22 patients. Multivariable Cox proportional hazard modeling identified atypical AVNRT (hazard ratio [HR], 5.83; 95% CI, 2.01–16.96; P=0.001), dual atrioventricular nodal only (HR, 4.09; 95% CI, 1.39–12.02; P=0.011), total radiofrequency lesions (HR, 1.06 per lesion; 95% CI, 1.01–1.12; P=0.032), and the use of a long sheath (HR, 3.52; 95% CI, 1.23–10.03; P=0.010) as predictors of AVNRT recurrence; quartile 1 patients were not at higher risk of recurrence (HR, 0.45; 95% CI, 0.10–1.97; P=0.29). Complete heart block requiring permanent pacing occurred in one quartile 2 patient at 14.9 years of age.ConclusionsPediatric AVNRT can be treated with radiofrequency‐SPM with high procedural efficacy and minimal risk of complications, including heart block. Atypical AVNRT and dual atrioventricular nodal physiology without inducible tachycardia remain challenging substrates.

A case series of very slow atrioventricular nodal reentrant tachycardia resembling junctional tachycardia.

IntroductionThe surface electrocardiography of typical atrioventricular nodal reentrant tachycardia (AVNRT) shows simultaneous ventricular‐atrial (RP) activation with pseudo R′ in V1 and typical heart rates ranging from 150 to 220/min. Slower rates are suspicious for junctional tachycardia (JT). However, occasionally we encounter typical AVNRT with slow ventricular rates. We describe a series of typical AVNRT cases with heart rates under 110/min.MethodsA total of 1972 patients with AVNRT who underwent slow pathway ablation were analyzed. Typical AVNRT was diagnosed when; (1) evidence of dual atrioventricular nodal conduction, (2) tachycardia initiation by atrial drive train with atrial‐His‐atrial response, (3) short septal ventriculoatrial time, and (4) ventricular‐atrial‐ventricular (V‐A‐V) response to ventricular overdrive (VOD) pacing with corrected post pacing interval‐tachycardia cycle length (cPPI‐TCL) > 110 ms. JT was excluded by either termination or advancement of tachycardia by atrial extrastimuli (AES) or atrial overdrive (AOD) pacing.ResultsWe found 11 patients (age 20−78 years old, six female) who met the above‐mentioned criteria. The TCL ranged from 560 to 782 ms. Except for one patient showing tachycardia termination, all patients demonstrated a V‐A‐V response and cPPI‐TCL over 110 ms with VOD. AES or AOD pacing successfully excluded JT by either advancing the tachycardia in 10 patients or by tachycardia termination in one patient. Slow pathway was successfully ablated, and tachycardia was not inducible in all patients.ConclusionsThis case series describes patients with typical AVNRT with slow ventricular rate (less than 110/min) who may mimic JT. We emphasize the importance of using pacing maneuvers to exclude JT.

B-PO03-009 DUAL AV NODE PATHWAYS MASQUERADING AS SYMPTOMATIC ATRIOVENTRICULAR CONDUCTION DISEASE: THE IMPORTANCE OF TREADMILL STRESS TESTING IN ESTABLISHING SYMPTOM-ARRHYTHMIA CORRELATION

Markedly prolonged AV conduction intervals (PR intervals >300ms) may represent slow pathway conduction in patients with previously undiagnosed dual AV node physiology. Treadmill stress testing is a simple and effective way to distinguish between dual AV node physiology and true AV nodal disease in patients with exertional dyspnea. 61 yo female with no significant past medical history referred to EP clinic for dual chamber pacemaker implantation. The patient presented with exercise intolerance secondary to exertional dyspnea and AV nodal conduction block thought to be contributing to her symptoms. Baseline EKG showed normal sinus rhythm and markedly prolonged PR interval at 420 ms. All other studies, including echocardiogram and pertinent bloodwork, were within normal limits. The patient agreed to proceed with exercise treadmill stress testing in an attempt to correlate her symptoms with suspected arrhythmias (AV conduction block). N/A Treadmill stress testing was performed. The patient exercised for 7 min 29 sec in a standard Bruce protocol (9.2 METS). Test was terminated secondary to fatigue and dyspnea. She exhibited a normal chronotropic response (86% MPHR). No ST segment changes consistent with ischemia were observed. Importantly, review of EKGs performed during testing revealed abrupt shortening of the PR interval during exercise. This response to exercise was consistent mechanistically with the existence of dual AV node physiology, as well as preferential fast-pathway conduction and retrograde slow-pathway block during exertion. Identification of dual-AVN physiology excluded the need for pacemaker implantation. While a markedly elevated PR interval can cause exertional dyspnea secondary to dyssynchronous atrial systole or progression to AV conduction block (Mobitz Type I/II). Establishing a symptom-arrhythmia correlation is a crucial diagnostic step. As outlined above, treadmill testing identified dual AVN physiology, and revealed benign preferential slow pathway conduction at rest as the source of the prolonged PR interval. This test excluded AV nodal disease as the source of symptoms, and ensured that the patient did not undergo unnecessary pacemaker implantation.

Comparison of electrophysiological characteristics of right- and left-sided Mahaim-type accessory pathways.

Mahaim-type accessory pathways (MAPs) are generally right-sided due to the embryological differentiation, but left-sided localization is also possible. This study aims to compare the clinical and electrophysiological characteristics of right- and left-sided MAPs. Of 251 patients diagnosed with AP by electrophysiological study between November 2015 and February 2020, 12 patients with MAP were included (right sided n = 8, left sided n = 4). MAP was diagnosed if; (1) no retrograde conduction; (2) anterograde decremental conduction; (3) adenosine sensitivity; and (4) Mahaim potential at successful ablation site were present. Ten of twelve MAPs were clustered on the lateral walls of the mitral (n = 3, 75%) and tricuspid annuli (n = 7, 87.5%). Right-sided MAPs were mostly long pathways extending toward the conduction system whereas left-sided MAPs were short extending toward the neighboring myocardium. For right- and left-sided APs, the median QRS times were 129 and 156 ms (p = .042), the median VAbl -RVApex intervals were -12 and 64 ms (p = .007), the median QRS-V(His) intervals were 16 and 86 ms (p = .120), and the median VAbl -QRS interval was -8 and 12 ms (p = .017), respectively. Coexistence of dual atrioventricular node physiology was observed only in right-sided APs (n = 3, 37.5%). MAPs are more typically located on the right but may rarely be seen on the left. Catheter ablation was associated with high success without complications.

Dual atrioventricular nodal pathways physiology and high-grade heart block

We report of case of an 87 year old lady with preexisting RBBB who developed LBBB after transcatheter aortic valve replacement (TAVR) for the treatment of severe aortic stenosis. She underwent pacemaker implantation, and subsequently developed high-grade atrioventricular (AV) block. Dual chamber pacing in the setting of complete heart block with a long programmed AV delay showed retrograde P waves. Ventricular pacing showed intact retrograde conduction. Shortening the programmed AV delay resulted in loss of retrograde P waves during dual chamber pacing. These findings are discussed.

Tachycardia cycle length alternans in orthodromic reciprocating tachycardia due to mutually dependent dual AV node physiology and retrograde supernormal conduction.

Tachycardia cycle length alternans in orthodromic reciprocating tachycardia due to mutually dependent dual AV node physiology and retrograde supernormal conduction.

Atrioventricular Nodal Reentrant Tachycardia in Very Elderly Patients: A Single-center Experience.

We present a series of elderly patients older than 80 years who had recurrent palpitations for decades and who were subsequently diagnosed with atrioventricular (AV) nodal reentrant tachycardia (AVNRT). Through a retrospective chart analysis, we identified 12 patients (nine females and three males) aged 88 years ± 3.7 years (range: 80–92 years) seen at our center from 2015 to 2016 for recurrent palpitations and supraventricular tachycardia (SVT) who were ultimately diagnosed with AVNRT. These patients had palpitations and had been treated for anxiety and panic attacks for decades. They underwent electrophysiology (EP) study and successful ablation of the slow pathway. The demographic data, symptoms, and EP characteristics during the EP studies of the patients were evaluated. All 12 patients experienced palpitations and all but three had documented SVT on a loop recorder or an event monitor. During EP study, all patients displayed slow-pathway conduction. Nine patients demonstrated discontinuous AV nodal conduction curves, while three showed continuous AV nodal conduction curves. The observed tachycardia rates were 496.7 ms ± 25.7 ms. Three patients had atrial fibrillation (AF), which was noted during monitoring with the implanted loop recorders. Tachycardia was induced with both burst atrial pacing and atrial extrastimuli in five patients and with extrastimuli only in two patients. In five patients, no tachycardia induction was noted, but these individuals showed evidence of dual AV node physiology. Successful elimination of residual slow-pathway conduction postablation and/or noninducibility of tachycardia in the postablation period were achieved in all patients. All patients remained symptom-free over a period of one year. The patients who had AF in addition to AVNRT also did not present any recurrent AF following AVNRT ablation but are being monitored for recurrence. AVNRT in elderly people is often confused with panic attacks; hence, reports of panic attacks in elderly people should be properly evaluated for an arrhythmic etiology.

Tachycardia induced cardiomyopathy due to dual atrioventricular nodal non reentrant tachycardia (RCDD code: VI 1A 9)

Dual atrioventricular nodal non‐reentrant tachycardia (DAVNNT) is a rarely diagnosed, sustained supraventricular arrhythmia. We report the case of a 39‐year‐old female with drug‐resistant, irregular, narrow QRS complex tachycardia which gradually led to tachycardia‐induced cardiomyopathy. Previously, this arrhythmia was recognized as atrial fibrillation, with several unsuccessful attempts at pulmonary vein isolation. Only after the correct diagnosis of DAVNNT was established, successful radiofrequency ablation of the slow pathway in the atrioventricular node was performed, with complete cure of the arrhythmia. JRCD 2019; 4 (3): 59-62.

Fasciculoventricular accessory pathway unmasked by a pseudo gap phenomenon

A 28 year old female with manifest preexcitation underwent electrophysiology study for intermittent palpitation. During progressively premature atrial extrastimuli, bypass tract was blocked before relative refractory period of AV node, making it unfeasible to observe the change of H-V interval and QRS morphology during decremental nodal conduction. However, dual AV node physiology, presented as a marked increase of A-H interval, occurred when a short-coupled extrastimulus was delivered, followed by a preexcited QRS with an H-V interval identical to that in sinus rhythm. This was an example of gap phenomenon involving accessory pathway and AV node. Diagnosis of fasciculoventricular bypass tract was made and ablation was therefore not performed.

Challenges in Narrow QRS Complex Tachycardia Interpretation.

Several arrhythmogenic substrates may generate narrow QRS complex tachycardia, frequently encountered in clinical practice. Some narrow QRS complex tachycardias, however, are sustained by an uncommon arrhythmogenic mechanism. Although rare, these forms should be taken into account in the differential diagnosis to avoid misdiagnosis and improper patient management. Dual atrioventricular node physiology can be responsible for different uncommon forms of narrow QRS complex tachycardia, also nonreentrant in mechanism. A ventricular origin also is possible, if the tachycardia site is located in the upper ventricular septum with fast ventricular propagation to the specific conduction system and narrowing of the QRS complex.

Cardiac Rhythm Disturbances in Heterotaxy Syndrome.

Heterotaxy syndrome is associated with complex cardiac malformations and cardiac conduction system abnormalities. Those with right atrial isomerism (RAI) have dual sinus nodes and dual atrioventricular nodes predisposing them to supraventricular tachycardia (SVT). Those with left atrial isomerism (LAI) lack a normal sinus node and are at risk of sinus node dysfunction (SND) and atrioventricular block (AV block). We report the occurrence and risk factors associated with arrhythmias in heterotaxy syndrome. A retrospective review of all heterotaxy syndrome patients born and treated at our institution between 2000 and 2014 was performed. A total of 40 patients were identified; 16/40 (40%) with LAI and 24/40 (60%) with RAI. There were 12 deaths during follow-up [LAI 3/16 (19%), RAI 9/24 (38%); p = 0.30]. Twenty-one patients had arrhythmias during a mean follow-up period of 5.4 years; 14/16 (87%) in LAI and 7/24 (29%) in RAI (p < 0.001). Freedom from arrhythmia at 1,3,5years of age was 75.0%, 37.9%, 22.7% in LAI, and 83.3%, 77.5%, 69.6% in RAI, respectively(p = 0.00261). LAI had a three-fold increase in developing arrhythmias. Left atrial isomerism was the only factor identified to be associated with arrhythmia occurrence. Arrhythmias were commonly seen in heterotaxy syndrome particularly in left isomerism with more than half of the patients having arrhythmias by 3years of age. Atrial situs was the only risk factor identified to be associated with arrhythmias, and close follow-up is warranted in these patients.