Slow-fast Atrioventricular Nodal Reentrant Research Articles

Differential response to right ventricular extrastimuli from the base and apex during long RP' supraventricular tachycardia.

We report a case of long RP' tachycardia diagnosed as fast-slow atrioventricular nodal reentrant tachycardia (AVNRT) with a bystander nodoventricular pathway (NVP). Differential responses to right ventricular extrastimuli from the base and apex highlighted the anatomical proximity of the NVP attachment, contributing to the diagnosis.

Unusual resetting of superior-type fast-slow atrioventricular nodal reentrant tachycardia with cycle length alternans by early spontaneous premature ventricular contraction.

The pacing maneuvers for supraventricular tachycardia with cycle length alternans are sometimes difficult, especially when diagnostic ventricular pacing does not conduct to the atrium. Even in such a situation, critical diagnostic findings can be obtained by spontaneous premature ventricular contraction.

Case Report

A patient suffered from recurrent episodes of palpitations and documented wide QRS complex tachycardia. Echocardiography revealed no obvious abnormal heart structure. A diagnostic electrophysiological study was performed and fast-slow atrioventricular nodal reentrant tachycardia with aberrancy was diagnosed. Successful slow pathway ablation rendered the tachycardia noninducible.

Unique electrophysiological properties of fast-slow atrioventricular nodal reentrant tachycardia characterized by a shortening of retrograde conduction time via a slow pathway manifested during atrial induction.

Electrophysiological properties of reentry circuits of fast-slow atrioventricular nodal reentrant tachycardia (F/S-AVNRT) may contribute to cyclic variability after atrial induction. In 156 atrial inductions of 33 patients with F/S-AVNRT, we measured the atrio-His (AH) and His-atrial (HA) intervals in the first cycle after the induction (AH[1] and HA[1], respectively), those in the second cycle (AH [2] and HA [2], respectively), and those during tachycardia that maintained a stable cycle length AH[T] and HA[T], respectively), and calculated the value of AH(1) minus AH(T) [ΔAH] and the value of HA(1) minus HA(T) [ΔHA] in each induction. According to the sum of ΔAH and ΔHA, tachycardia variability was classified as incremental (<-20), balanced (-20 to 20), or decremental (>20). ΔAH and ΔHA were significantly different between the three responses: 6 ± 28 and -67 ± 39 in 55 inductions (35%) with an incremental response, 20 ± 10 and -23 ± 28 in 59 (38%) with a balanced response, and 54 ± 44 and 4 ± 50 in 42 (27%) with a decremental response, respectively. Incremental response was reproducibly and consistently observed in 33% of patients. HA(2) was similar to HA(T) in inductions with an incremental response. These results suggest that incremental response can be manifested only in the first cycle when HA(1) is excessively shortened, approximating a retrograde conduction time over a slow pathway, in contrast, and far superior to a decremental delay of AH(1). In specific patients with F/S-AVNRT, poorly recognized, electrophysiological properties of shortening a retrograde conduction time over a slow pathway was manifested during atrial induction.

A contemporary view of atrioventricular nodal physiology.

In delaying transmission of the cardiac impulse from the atria to the ventricles, the atrioventricular (AV) node serves a critical function in augmenting ventricular filling during diastole and limiting the ventricular response during atrial tachyarrhythmias. The complex structure of the nodal region, however, also provides the substrate for reentrant rhythms. Recent discoveries have elucidated the cellular basis and anatomical determinants of slow conduction in the node. Based on analysis of gap junction proteins, distinct structural components of the AV node have been defined, including the compact node, right and left inferior nodal extensions, the lower nodal bundle, and transitional tissue. Emerging evidence supports the role of the inferior nodal extensions in mediating slow pathway conduction. The most common form of reentry involving the node, slow-fast AV nodal reentrant tachycardia (AVNRT), utilizes the inferior nodal extensions for anterograde slow pathway conduction; the structures responsible for retrograde fast pathway activation in the superior septum are less well defined and likely heterogeneous. Atypical forms of AVNRT arise from circuits that activate at least one of the inferior extensions in the retrograde direction.

Atrial and ventricular activation sequence after ventricular induction/entrainment pacing during fast–slow atrioventricular nodal reentrant tachycardia: New insight into the use of V-A-A-V for the differential diagnosis of supraventricular tachycardia

The atrial and ventricular response observed immediately after cessation of ventricular induction/entrainment pacing is commonly analyzed to discriminate atrial tachycardia from other supraventricular tachycardias during electrophysiologic studies. However, the response in fast-slow atrioventricular nodal reentrant tachycardia (F/S-AVNRT) remains poorly investigated. The purpose of this study was to analyze the atrial andventricular activation patterns after ventricular pacing in F/S-AVNRT. We enrolled 28 patients with F/S-AVNRT incorporating a typical slow pathway (typ-F/S-AVNRT) and 9 patients with F/S-AVNRT incorporating a superior slow pathway (sup-F/S-AVNRT). The V-A-A-V response was observed in 14 patients (38%) with F/S-AVNRT, more commonly in patients with sup-F/S-AVNRT than in those with typ-F/S-AVNRT (89% vs 21%, P = .0003). The underlying mechanisms included (1) a double atrial response (DAR) in 13 patients; (2) an anterograde block at the lower common pathway once after ventricular pacing in 2 patients; and (3) a pseudo-A-A-V response in 2 patients. The DAR was characterized by a V-A-A-V interatrial interval that was 55 ± 60 ms shorter than the tachycardia cycle length, whereas the block at the lower common pathway or infrahisian block had a V-A-A-V interatrial interval that was almost equal to or longer than the tachycardia cycle length. The V-A-A-V activation sequence immediately after ventricular induction/entrainment pacing is observed in patients with F/S-AVNRT, particularly in patients with sup-F/S-AVNRT, and is caused by multiple mechanisms, including a DAR, which is the major etiology.

Successful Ablation of Atypical Atrioventricular Nodal Reentrant Tachycardia From a Noncoronary Sinus of Valsalva

An 81-year-old man with long RP narrow QRS tachycardia underwent catheter ablation. Ventricular pacing reset the atrial cycle over a retrograde slow pathway, followed by termination of the tachycardia without atrial capture, confirming the diagnosis of fast-slow atrioventricular nodal reentrant tachycardia (AVNRT). The earliest atrial activation during tachycardia was found in the noncoronary sinus of Valsalva, where the first delivery of radiofrequency energy terminated and eliminated the inducibility of the tachycardia, by retrograde conduction block over the slow pathway. This is the first report of a fast-slow AVNRT, with successful ablation of the slow pathway from a noncoronary sinus of Valsalva.

Differential ventricular entrainmentにて診断しえたfast-slow AVNRTの1例

Differential ventricular entrainmentにて診断しえたfast-slow AVNRTの1例

Initial shortening of the tachycardia cycle length after the induction of fast-slow atrioventricular nodal reentrant tachycardia may support slow pathway as an antegrade limb of the reentry circuit

Introduction: It remains controversial whether fast pathway (FP) is actually incorporated as an antegrade limb of the reentry circuit in fast-slow (F-S) atrioventricular nodal reentrant tachycardia (AVNRT) with the earliest atrial activation at coronary sinus ostium, presenting long RP tachycardia, because antegrade conduction over slow pathway (SP) is occasionally observed during the tachycardia. Although double ventricular responses (DVR) in which single atrium impulse conducts to the ventricle simultaneously over FP and SP are frequently observed during slow-fast (S-F) AVNRT, these phenomena have not been recognized during F-S AVNRT. The purpose was to verify our hypothesis that SP is incorporated as an antegrade limb of the reentry circuit in F-S AVNRT, by the detection of DVR during F-S AVNRT. Methods: In 6 F-S AVNRT, 8 S-F AVNRT and 8 atrioventricular reentrant tachycardia (AVRT) reproducibly inducible with atrial extrastimulation (S1-S2) or overdrive pacing (S2-S2), we examined an initial cyclic variation after the induction of the tachycardia by measuring interhisian intervals of H2-H3, H3-H4 and H4-H5. Results: As shown in table, the tachycardia cycle length immediately after the induction was paradoxically shorter than the subsequent tachycardia cycle length in F-S AVNRT only. Temporal P-QRS variation during F-S AVNRT and a complication of S-F AVNRT with the same earliest atrial site in 5 F-S AVNRT (83%) suggested the presence of low common pathway (LCP) located below the AVN reentry circuit. Values are expressed in ms. *p<0.05 vs H4-H5 interval minus H3-H4 interval. Conclusions: Paradoxical shortening of H2-H3 in F-S AVNRT may be explained by DVR in which H2 and H3 is antegradely captured over FP and SP, respectively, followed by slow-slow AVNRT with a long LCP, presenting long RP tachycardia.

Rapid palpitations: three of a kind?

The first part of the ECG shows a wide QRS tachycardia with a right bundle branch block (RBBB) morphology, an inferior axis and a heart rate of 240 bpm (tachycardia cycle length (TCL) of 250 ms). The middle part shows a narrow QRS tachycardia with an intermediate axis and the same heart rate of 240 bpm (TCL 250 ms). In the last part a wide QRS tachycardia is observed, although with a different, left bundle branch block (LBBB) morphology and horizontal axis. The heart rate decreased slightly to 195 bpm (TCL 310 ms). In the middle part, during tachycardia with a narrow QRS complex, a P wave can be suspected on top of the T wave with an RP interval longer than the PR. Especially leads aVR, lead I and the inferior leads permit the visualisation of the P waves. The morphology of the P wave is difficult to see, but a negative polarity in the inferior leads and positive polarity in aVR suggest the presence of a retrograde P wave. The differential diagnosis will be: orthodromic atrioventricular reentrant tachycardia (AVRT), atypical or fast-slow atrioventricular nodal reentrant tachycardia (AVNRT), or atrial tachycardia (AT). The pattern of QRS alternans during the narrow QRS tachycardia points towards the direction of an AVRT, although it does not rule out AT or AVNRT. The clue to the diagnosis is the change in QRS morphology during the ongoing tachycardia. During tachycardia with RBBB morphology, the same TCL as during the narrow QRS tachycardia is seen (250 ms). In contrast, changing to LBBB the tachycardia slows down with a TCL of 310 ms. In case of an AVNRT or AT the ventricles are not part of the reentrant circuit, so a conduction block in either of the bundle branches would not influence the heart rate. The fact that the heart rate slows during LBBB means that the slowed conduction towards the left ventricle influences the cycle length and proves that the ventricle is part of the circuit and an orthodromic AVRT using a left-sided accessory pathway (AP) is proven. The fact that during RBBB the heart rate remains unchanged confirms the diagnosis of the left-sided AP (Fig. 2). During the electrophysiology study the AP was located lateral on the mitral annulus and was successfully ablated. Afterwards no tachycardia could be induced. Fig. 2 a. AV conduction with RBBB does not influence the conduction time to the retrograde conducting AP. b. AV conduction without bundle blanch block. c. During LBBB the conduction time over the ventricle is longer because of the delayed right to left conduction ...

Rapid palpitations: three of a kind?

The first part of the ECG shows a wide QRS tachycardia with a right bundle branch block (RBBB) morphology, an inferior axis and a heart rate of 240 bpm (tachycardia cycle length (TCL) of 250 ms). The middle part shows a narrow QRS tachycardia with an intermediate axis and the same heart rate of 240 bpm (TCL 250 ms). In the last part a wide QRS tachycardia is observed, although with a different, left bundle branch block (LBBB) morphology and horizontal axis. The heart rate decreased slightly to 195 bpm (TCL 310 ms). In the middle part, during tachycardia with a narrow QRS complex, a P wave can be suspected on top of the T wave with an RP interval longer than the PR. Especially leads aVR, lead I and the inferior leads permit the visualisation of the P waves. The morphology of the P wave is difficult to see, but a negative polarity in the inferior leads and positive polarity in aVR suggest the presence of a retrograde P wave. The differential diagnosis will be: orthodromic atrioventricular reentrant tachycardia (AVRT), atypical or fast-slow atrioventricular nodal reentrant tachycardia (AVNRT), or atrial tachycardia (AT). The pattern of QRS alternans during the narrow QRS tachycardia points towards the direction of an AVRT, although it does not rule out AT or AVNRT. The clue to the diagnosis is the change in QRS morphology during the ongoing tachycardia. During tachycardia with RBBB morphology, the same TCL as during the narrow QRS tachycardia is seen (250 ms). In contrast, changing to LBBB the tachycardia slows down with a TCL of 310 ms. In case of an AVNRT or AT the ventricles are not part of the reentrant circuit, so a conduction block in either of the bundle branches would not influence the heart rate. The fact that the heart rate slows during LBBB means that the slowed conduction towards the left ventricle influences the cycle length and proves that the ventricle is part of the circuit and an orthodromic AVRT using a left-sided accessory pathway (AP) is proven. The fact that during RBBB the heart rate remains unchanged confirms the diagnosis of the left-sided AP (Fig. 2). During the electrophysiology study the AP was located lateral on the mitral annulus and was successfully ablated. Afterwards no tachycardia could be induced. Fig. 2 a. AV conduction with RBBB does not influence the conduction time to the retrograde conducting AP. b. AV conduction without bundle blanch block. c. During LBBB the conduction time over the ventricle is longer because of the delayed right to left conduction ...

Selective slow pathway ablation using transseptal approach in a patient with surgically corrected partial atrioventricular canal defect and atrioventricular nodal reentrant tachycardia of the common type

A 26-year-old woman with partial atrioventricular (AV) canal defect surgically closed with pericardial patch in a mode that the triangle of Koch had become part of the left atrium underwent successful slow pathway ablation for slow-fast AV nodal reentrant tachycardia. Transseptal approach was used because of the atypical post-operative anatomy. Transseptal catheter ablation of the slow pathway can be a reasonable and safe alternative in patients subjected to this type of operation.

Pseudo–Atrial Fibrillation, Rare Manifestation of Multiple Anterograde Atrioventricular Nodal Pathways

In patients with dual or multiple atrioventricular (AV) nodal pathways manifesting nonreentrant tachycardia or unusual forms of AV nodal reentry, paroxysmal atrial fibrillation is often misdiagnosed and patients may erroneously be considered for pulmonary vein isolation. Multiple anterograde slow AV nodal pathways, identified by >1 discontinuity in the anterograde AV nodal conduction curve, are not rare in patients with slow-fast AV nodal reentrant tachycardia (AVNRT). However, only 1 slow AV nodal pathway is usually involved in anterograde conduction during tachycardia. It was reported that patients with multiple anterograde slow AV nodal pathways presented with different tachycardia cycle lengths. For the first time, 2 patients with AVNRT in which maintenance of tachycardia was strictly dependent on participation of 3 different anterograde slow AV nodal pathways in an uniquely alternating sequence are reported. In both patients, a single application of radiofrequency energy in the posterior aspect of Koch's triangle eliminated simultaneously all evidence of anterograde slow pathway conduction. These findings implied that functional differences in a determined circuit based on nonuniform anisotropy rather than anatomically distinct pathways form the electrophysiologic basis for this rare variant of AVNRT. In conclusion, particularly in patients with lone atrial fibrillation who are potential candidates for pulmonary vein isolation, careful analysis of the surface electrocardiogram during irregular supraventricular tachycardia and invasive electrophysiologic examination helps identify rare arrhythmia mechanisms that can be cured by slow pathway ablation alone.

Inducible Atrioventricular Nodal Reentrant Echo Behind Organic 2:1 Infra‐Hisian Block During Sinus Rhythm

A 77-year-old male patient with an intermittent 2:1 infra-Hisian block during sinus rhythm was presented with dizziness and near-syncope. During electrophysiological (EP) study, dual atrioventricular (AV) nodal pathways and retrograde fast pathway were easily induced by atrial and ventricular programmed stimulation, respectively. A typical slow-fast AV nodal reentrant echo beat also could be demonstrated by single atrial extrastimulation. Atrioventricular nodal reentrant tachycardia (AVNRT) can occasionally exhibit 2:1 AV block. Conversely, AV nodal reentry property had been rarely reported behind 2:1 infra-Hisian block. The EP presentation from this case may support the notion that tissues below the His are not part of the reentrant circuit of AVNRT.

The nature of the retrograde and antegrade slow pathways differ in uncommon fast-slow atrioventricular nodal reentrrant tachycardia

The nature of both the antegrade and retrograde slow pathway conduction of uncommon fast-slow atrioventricular nodal reentrant tachycardia (AVNRT) has not been precisely described. Anatomical and electrophysiological characteristics of slow pathways were investigated.

Electrophysiological Characteristics of Junctional Rhythm During Ablation of the Slow Pathway in Different Types of Atrioventricular Nodal Reentrant Tachycardia

Junctional rhythm (JR) is commonly observed during radiofrequency (RF) ablation of the slow pathway for atrioventricular (AV) nodal reentrant tachycardia. However, the atrial activation pattern and conduction time from the His-bundle region to the atria recorded during JR in different types of AV nodal reentrant tachycardia have not been fully defined. Forty-five patients who underwent RF ablation of the slow pathway for AV nodal reentrant tachycardia were included; 27 patients with slow-fast, 11 patients with slow-intermediate, and 7 patients with fast-slow AV nodal reentrant tachycardia. The atrial activation pattern and HA interval (from the His-bundle potential to the atrial recording of the high right atrial catheter) during AV nodal reentrant tachycardia (HA(SVT)) and JR (HA(JR)) were analyzed. In all patients with slow-fast AV nodal reentrant tachycardia, the atrial activation sequence recorded during JR was similar to that of the retrograde fast pathway, and transient retrograde conduction block during JR was found in 1 (4%) patient. The HA(JR) was significantly shorter than the HA(SVT) (57 +/- 24 vs 68 +/- 21 ms, P < 0.01). In patients with slow-intermediate AV nodal reentrant tachycardia, the atrial activation sequence of the JR was similar to that of the retrograde fast pathway in 5 (45%), and to that of the retrograde intermediate pathway in 6 (55%) patients. Transient retrograde conduction block during JR was noted in 1 (9%) patient. The HA(JR) was also significantly shorter than the HA(SVT) (145 +/- 27 vs 168 +/- 29 ms, P = 0.014). In patients with fast-slow AV nodal reentrant tachycardia, retrograde conduction with block during JR was noted in 7 (100%) patients. The incidence of retrograde conduction block during JR was higher in fast-slow AV nodal reentrant tachycardia than slow-fast (7/7 vs 1/11, P < 0.01) and slow-intermediate AV nodal reentrant tachycardia (7/7 vs 1/27, P < 0.01). In patients with slow-fast and slow-intermediate AV nodal reentrant tachycardia, the JR during ablation of the slow pathway conducted to the atria through the fast or intermediate pathway. In patients with fast-slow AV nodal reentrant tachycardia, there was no retrograde conduction during JR. These findings suggested there were different characteristics of the JR during slow-pathway ablation of different types of AV nodal reentrant tachycardia.

Heterogeneity of anterograde fast-pathway and retrograde slow-pathway conduction patterns in patients with the fast-slow form of atrioventricular nodal reentrant tachycardia: electrophysiologic and electrocardiographic considerations.

This study sought to define the electrophysiologic and electrocardiographic characteristics of fast-slow atrioventricular nodal reentrant tachycardia (AVNRT). In fast-slow AVNRT the retrograde slow pathway (SP) is located in the posterior septum, whereas the anterograde fast pathway (FP) is located in the anterior septum; however, exceptions may occur. Twelve patients with fast-slow AVNRT were studied. To determine the location of the retrograde SP, atrial activation during AVNRT was examined while recording the electrograms from the low septal right atrium (LSRA) on the His bundle electrogram and the orifice of the coronary sinus (CS). Further, to investigate the location of the anterograde FP, single extrastimuli were delivered during AVNRT both from the high right atrium and the CS. The CS activation during AVNRT preceded the LSRA in six patients (posterior type); LSRA activation preceded the CS in three patients (anterior type), and in the remaining three both sites were activated simultaneously (middle type). In the anterior type, CS stimulation preexcited the His and the ventricle without capturing the LSRA electrogram (atrial dissociation between the CS and the LSRA), suggesting that the anterograde FP was located posterior to the retrograde SP. In the posterior and middle types, high right atrial stimulation demonstrated atrial dissociation, suggesting that the anterograde FP was located anterior to the SP. In the posterior and middle types, retrograde P waves in the inferior leads were deeply negative, whereas they were shallow in the anterior type. Fast-slow AVNRT was able to be categorized into posterior, middle and anterior types according to the site of the retrograde SP. The anterior type AVNRT, where an anteriorly located SP is used in the retrograde direction and a posteriorly located FP in the anterograde direction, appears to represent an anatomical reversal of the posterior type which uses a posterior SP for retrograde and an anterior FP for anterograde conduction. Anterior type AVNRT should be considered in the differential diagnosis of long RP (RP > PR intervals) tachycardias with shallow negative P waves in the inferior leads.