Coexistence of a Classical Nodoventricular Accessory Pathway With a Left-Sided Mahaim Accessory Pathway

The coexistence of 2 Mahaim pathways represents a diagnostic challenge. We present a case in which the SH/HA intervals were useful for identifying concealed nodoventricular or His-ventricular pathways.

Systematic observation-based diagnosis of atrioventricular nodal reentrant tachycardia with a bystander concealed nodoventricular pathway

Background

This study aimed to establish a systematic method for diagnosing atrioventricular nodal reentrant tachycardia (AVNRT) with a bystander concealed nodoventricular pathway (cNVP).

Methods

We analyzed 13 cases of AVNRT with a bystander cNVP, 11 connected to the slow pathway (cNVP-SP) and two to the fast pathway (cNVP-FP), along with two cases of cNVP-related orthodromic reciprocating tachycardia (ORT).

Results

The diagnostic process was summarized in three steps. Step 1 was identification of the presence of an accessory pathway by resetting the tachycardia with delay (n = 9) and termination without atrial capture (n = 4) immediately after delivery of a His-refractory premature ventricular contraction (PVC). Step 2 was exclusion of ORT by atrio-His block during the tachycardia (n = 4), disappearance of the reset phenomenon after the early PVC (n = 7), or dissociation of His from the tachycardia during ventricular overdrive pacing (n = 1). Moreover, tachycardia reset/termination without the atrial capture (n = 2/2) 1 cycle after the His-refractory PVC was specifically diagnostic. Exceptionally, the disappearance of the reset phenomenon was also observed in the two cNVP-ORTs. Step 3 was verification of the AVN as the cNVP insertion site, evidenced by an atrial reset/block preceding the His reset/block in fast-slow AVNRT with a cNVP-SP and slow-fast AVNRT with a cNVP-FP or His reset preceding the atrial reset in slow-fast AVNRT with a cNVP-SP.

Conclusion

AVNRT with a bystander cNVP can be diagnosed in the three steps with few exceptions. Notably, tachycardia reset/termination without atrial capture one cycle after delivery of a His-refractory PVC is specifically diagnostic.

Arrhythmias Utilizing Concealed Nodoventricular or His-Ventricular Pathways: A Structured Approach to Diagnosis and Management

OBJECTIVES

This study sought to describe the electrophysiologic characteristics, diagnostic maneuvers, and treatment of a series of arrhythmias using concealed nodoventricular (cNV) or His-ventricular (cHV) pathways.

BACKGROUND

Confirming the presence and participation of cNV or cHV pathways in tachyarrhythmias is challenging.

METHODS

We present 4 cases of tachycardias with a participatory cNV or cHV pathway.

RESULTS

The first patient had a narrow complex tachycardia with ventriculoatrial dissociation. Findings of an entrainment pacing from the right ventricle and fused premature ventricular complexes suggested cNV pathway involvement. The second patient had nonsustained narrow complex tachycardia with more ventricular than atrial complexes. The tachycardia exhibited an anterograde His-right bundle (RB) activation sequence and normal His-ventricular (HV) interval and consistently terminated with fused ventricular extra stimuli, suggesting cNV pathway participation. The third patient had a wide complex tachycardia (WCT) with either a right or left bundle branch block pattern. The WCT showed an eccentric His-RB activation sequence and short HV interval and terminated with fused premature ventricular complexes, suggesting a cHV (or concealed fasciculoventricular) pathway involvement. The fourth patient had a WCT with alternating bundle branch block morphologies with a short HV interval. Entrainment from the basal right ventricle demonstrated fusion and a short postpacing interval, suggesting cHV (or fasciculoventricular) pathway involvement. Ablation at the proximal RB rendered the tachycardia noninducible.

CONCLUSIONS

A structured approach can help diagnose and treat cNV or cHV pathways. We emphasize the importance of evaluating both the His-RB activation pattern and HV interval during sinus rhythm and tachycardia as well as the ventricular pacing study.

Novel Diagnostic Observations of Nodoventricular/Nodofascicular Pathway-Related Orthodromic Reciprocating Tachycardia Differentiating From Atrioventricular Nodal Re-Entrant Tachycardia

OBJECTIVES

This study sought to assess the performance of current diagnostic criteria and identify additional electrophysiological features differentiating orthodromic reciprocating tachycardia (ORT) with a concealed nodoventricular/nodofascicular (NV/NF) pathway from atrioventricular nodal re-entrant tachycardia (AVNRT).

BACKGROUND

Diagnosing sustained supraventricular tachycardia (SVT) despite the occurrence of ventriculoatrial block (VAB) is challenging.

METHODS

We analyzed electrograms of 25 sustained SVTs (9 NV/NF-ORTs [n = 7/2] and 16 AVNRTs) with VAB and 91 AVNRTs without VAB (for reference).

RESULTS

More than 1 SVT, each with a different ventriculoatrial interval, was commonly induced in AVNRT cases (75%) but not in NV/NF-ORT cases (0%; p = 0.0005). Wenckebach VAB was common in NV/NF-ORTs (78%), but VAB patterns varied in AVNRTs. The His-His interval transiently prolonged in the following beat after the VAB in most AVNRTs but rarely did in NV/NF-ORTs (79% vs. 22%; p = 0.01). NV/NF-ORT was diagnosed by His-refractory premature ventricular contractions (n = 5) and the findings during right ventricular overdrive pacing showing an uncorrected/corrected post-pacing interval (PPI)-tachycardia cycle length (TCL) ≤115/110 ms (n = 5/5), orthodromic His capture (n = 6), and V-V-A (ventricle-ventricle-atrial response) response (n = 3). A single form of induced SVT (positive predictive value [PPV]: 69%; negative predictive value [NPV]: 100%), Wenckebach VAB (PPV: 70%; NPV: 87%), stable His-His interval despite VAB (PPV: 70%; NPV: 85%), orthodromic His capture (PPV: 100%; NPV: 97%), and V-V-A response (PPV: 100%; NPV: 95%) characterized NV/NF-ORT, and a PPI-TCL of ≤125 ms (PPV: 100%; NPV: 100%) characterized NV-ORT.

CONCLUSIONS

Induction of a single SVT form, Wenckebach VAB, stable His-His interval despite VAB, orthodromic His capture, and V-V-A response appeared to discriminate NV/NF-ORT from AVNRT, with a PPI-TCL of ≤125 ms discriminating NV-ORT from NF-ORT and AVNRT.

Clinical Features and Sites of Ablation for Patients With Incessant Supraventricular Tachycardia From Concealed Nodofascicular and Nodoventricular Tachycardias. JACC Clin Electrophysiol. 2017;3:1547-1556. [PMID: 29759837 DOI: 10.1016/j.jacep.2017.07.015]

OBJECTIVES

This study sought to describe the clinical features and sites of successful ablation for incessant nodofascicular (NF) and nodoventricular (NV) tachycardias.

BACKGROUND

Incessant supraventricular tachycardias have been associated with tachycardia-induced cardiomyopathies and have been previously attributed to permanent junctional reciprocating tachycardias, atrial tachycardias, and atrioventricular nodal re-entrant tachycardias. Incessant concealed NF and NV tachycardias have not been described previously.

METHODS

Three cases of incessant concealed NF and NV re-entrant tachycardias were identified from 2 centers.

RESULTS

The authors describe 3 cases with incessant supraventricular tachycardia resulting from NV (2 cases) and NF (1 case) pathways. Atrioventricular nodal re-entrant tachycardia was excluded by His synchronous premature ventricular complexes that either delayed or terminated the tachycardia. Ventricular pacing showed constant and progressive fusion in cases 1 and 3. In 2 cases, there was spontaneous initiation with a 1:2 response (cases 1 and 3); the presence of retrograde longitudinal dissociation or marked decremental pathway conduction in cases 1 and 3 sustains these tachycardias. The NV pathway was successfully ablated in the slow pathway region in case 3 and at the right bundle branch in case 1. The NF pathway was successfully ablated within the proximal coronary sinus in case 2.

CONCLUSIONS

This is the first report of incessant supraventricular tachycardia using concealed NF or NV pathways. These tachycardias demonstrated spontaneous initiation from sinus rhythm with a 1:2 response and retrograde longitudinal dissociation or marked decremental pathway conduction. Successful ablation was achieved at either right-sided sites or within the coronary sinus.