New Criteria During Right Ventricular Pacing to Determine the Mechanism of Supraventricular Tachycardia

Abstract

Background-Right ventricular pacing (RVP) during supraventricular tachycardia produces progressive QRS fusion before the QRS morphology becomes stable. This transition zone (TZ) may provide useful information for differentiating orthodromic reciprocating tachycardia (ORT) from atrioventricular nodal reentrant tachycardia and atrial tachycardia independent of entrainment success. Methods and Results-We studied the effect of properly timed RVP on atrial timing during the TZ in 92 patients with supraventricular tachycardia who had RVP within 40 ms of the tachycardia cycle length. The TZ during RVP includes progressively fused QRS complexes and the first paced complex with a stable QRS morphology based on analysis of the 12-lead ECG. We also measured the stimulus-atrial interval from the end of the TZ and with each QRS complex thereafter until pacing was terminated or ventriculo-atrial block occurred. A fixed stimulus-atrial interval was defined as variation Ͻ10 ms during RVP. Atrial preexcitation, postexcitation, or supraventricular tachycardia termination with abrupt ventriculo-atrial block was observed within the TZ in 32 of 34 patients with ORT. A fixed stimulus-atrial interval was established within the TZ in 33 of 34 patients with ORT. At least 1 of these 2 responses was observed in all patients with ORT. None of the patients with atrioventricular nodal reentrant tachycardia or atrial tachycardia had atrial timing perturbed or a fixed stimulus-atrial interval established within the TZ. Conclusions-During RVP within 40 ms of the tachycardia cycle length, ORT is the likely mechanism when atrial timing is perturbed or a fixed stimulus-atrial interval is established within the TZ. (Circ Arrhythm Electrophysiol. 2010;3:578-584.)

Classification, Electrophysiological Features and Therapy of Atrioventricular Nodal Reentrant Tachycardia

“…Usually, a combined anatomical and mapping approach is employed with ablation lesions delivered at the inferior or mid part of the triangle of Koch. 60,61 Multicomponent atrial electrograms or low amplitude potentials, although not specific for identification of slow pathway -SA-VA and cPPI-TCL intervals [44][45][46][47] -Differential entrainment or cessation 48 Cumbersome Delta HA during V Pre-excitation index 49 Differential entrainment 58 pacing and tachycardia 36 Entrainment VHA pattern 37 -Anterograde His capture 50 Para-Hisian pacing 38 -Progressive fusion during or after the transition zone 51,52 Induction of retrograde Delta HA during entrainment RBBB 39 and tachycardia 53 SA init -VA and cPPI init --Para-Hisian entrainment [54][55][56] TCL conduction, are successfully used to guide ablation at these areas.…”

Differential Responses of the Septal Ventricle and the Atrial Signals During Ongoing Entrainment

“…4 We analyzed the first atrial and SVE (parahisian) signals that are advanced for the paced wave fronts from the tachycardia cycle length (captured by the paced wave front). The presence of discordant timing between the corresponding atrial and SVE signals for at least 1 cycle was defined as a differential response.…”

“…Several diagnostic maneuvers can aid differential diagnosis, including a return cycle after continuous entrainment from the right ventricular apex (RVA), 1,2 tachycardia resetting with electrocardiographic fusion, 3,4 and even responses to single ventricular extrastimulus.5 However, it has been reported that ≤15% to 20% of the tachycardia mechanism could be interrupted by the entrainment maneuvers. 5 In these instances, the utility of RVA pacing during tachycardia at the beginning of the entrainment attempt has received less attention as a diagnostic technique.…”

“…Several diagnostic maneuvers can aid differential diagnosis, including a return cycle after continuous entrainment from the right ventricular apex (RVA), 1,2 tachycardia resetting with electrocardiographic fusion, 3,4 and even responses to single ventricular extrastimulus.…”

“…4 Perturbation of atrial timing during this TZ is a specific feature of macroreentry, with the ventricle being part of the circuit, allowing for the fusion of the ventricle while resetting the atrium. Another similar way to demonstrate it is a single ventricular extrastimuli delivered during refractory His or displaying fusion at the surface ECG 6 because even one beat of reset/entrainment (whether single extrastimuli or onset of pacing) is diagnostically sufficient.…”