Entrainment Mapping of a Concealed Nodoventricular Accessory Pathway in a Man with Complete Heart Block and Tachycardia-Induced Cardiomyopathy

Electrophysiological manifestations of rare supra-ventricular tachycardias with concealed nodo-ventricular fibers

PURPOSE

To clarify the electrophysiological mechanism of supra-ventricular tachycardias (SVT) with concealed nodo-ventricular (NV) fibers.

METHODS

We studied the intra-cardiac electrograms during electrophysiological study (EPS) of three cases of SVT which concerned concealed NV fibers. Electrophysiological maneuvers including right ventricular apex entrainments, RS2 stimuli, adenosine triphosphate injection and so on were done for differential diagnosis before ablation.

RESULTS

Among these patients, one had atrio-ventricular nodal reentrant tachycardia (AVNRT) with a bystander NV fiber; the other 2 had NV fiber mediated orthodromic reentrant tachycardias (NVRT). VA dissociation was observed during SVT in all 3 cases with an antegrade His bundle conduction sequence. Ventricular stimulation at His refractory period reset the H-H intervals and the V-V intervals sequentially, suggesting the existence of a retrogradely conductive accessory pathway. Adenosine injection could terminate these tachycardias. The cycle length of an NVRT prolonged during the status of functional right bundle branch block, suggesting that the fiber located on the right side. Multiple QRS fusion morphologies during ventricular entrainments or ventricular stimulation at His refractory period at a fixed position could be observed in these cases.

CONCLUSIONS

Concealed NV fibers can either mediate orthodromic reentrant tachycardia or be a bystander of AVNRT. V-A dissociation usually occur during such SVTs. Dissociation of H and V due to entrainment of right ventricular apex is a newly discovered maneuver to differentiate AVNRT from NVRT.

Unusual variants of pre-excitation: From anatomy to ablation: Part III-Clinical presentation, electrophysiologic characteristics, when and how to ablate nodoventricular, nodofascicular, fasciculoventricular pathways, along with considerations of permanent junctional reciprocating tachycardia

The recognition of the presence, location, and properties of unusual accessory pathways for atrioventricular conduction is an exciting, but frequently a difficult, challenge for the clinical cardiac arrhythmologist. In this third part of our series of reviews, we discuss the different steps required to come to the correct diagnosis and management decision in patients with nodofascicular, nodoventricular, and fasciculo-ventricular pathways. We also discuss the concealed accessory atrioventricular pathways with the properties of decremental retrograde conduction that are associated with the so-called permanent form of junctional reciprocating tachycardia. Careful analysis of the 12-lead electrocardiogram during sinus rhythm and tachycardias should always precede the investigation in the catheterization room. When using programmed electrical stimulation of the heart from different intracardiac locations, combined with activation mapping, it should be possible to localize both the proximal and distal ends of the accessory connections. This, in turn, should then permit the determination of their electrophysiologic properties, providing the answer to the question "are they incorporated in a tachycardia circuit?". It is this information that is essential for decision-making with regard to the need for catheter ablation, and if necessary, its appropriate site.

Anteroseptal basal right ventricular entrainment is simple and superior to apical entrainment in identifying mechanism of supraventricular tachycardia

BACKGROUND

Differentiation between atrioventricular nodal reentry tachycardia (AVNRT) and atrioventricular reentrant tachycardia (AVRT) can be sometimes challenging. Apical right ventricular (RV) entrainment can help in differentiation; however, it has some fallacies. We thought to compare the accuracy of anteroseptal basal RV entrainment to RV apical entrainment in identifying the mechanism of supraventricular tachycardia (SVT).

METHODS

Forty-two consecutive patients with SVT who underwent catheter ablation were prospectively studied. Apical RV entrainment was performed initially followed by basal entrainment from the anteroseptal basal RV avoiding His or atrial capture. Postpacing interval (PPI), PPI-tachycardia cycle length (TCL), corrected PPI-TCL, and stimulus-atrial minus ventricular-atrial (VA) intervals were measured.

RESULTS

Entrainment was achieved from both sites of RV in 34 patients (ten men; mean age 42 ± 15 years), 20 with typical AVNRT, 1 with atypical AVNRT, and 13 with AVRT (eight left sided, four right sided, and one septal accessory pathways). PPI-TCL, corrected PPI (cPPI)-TCL, and stimulus-atrial-VA intervals were significantly longer with basal entrainment in AVNRT (171 ± 30 vs. 153 ± 22 ms (p = 0.003), 148 ± 21 vs. 131 ± 20 ms (p = 0.002), and 145 ± 17 vs. 136 ± 15 ms (p = 0.005), respectively). Receiver-operating characteristic curves showed higher AUC for the above parameters with basal entrainment compared to apical entrainment. Cutoff values of basal PPI-TCL of >110 ms and cPPI-TCL of >95 ms had better sensitivities (100 % for both vs. 95 and 90 %, respectively, for apical values) and specificities (85 and 92 % vs. 77 and 92 %, respectively) for diagnosis of AVNRT.

CONCLUSION

Basal RV entrainment from the anteroseptal basal RV is a simple maneuver that is superior to apical ventricular entrainment in identifying the mechanism of SVT.