Case Of Atrioventricular Nodal Reentrant Tachycardia Research Articles

Meta-Analysis of Genome-Wide Association Studies Reveals Genetic Mechanisms of Supraventricular Arrhythmias.

Substantial data support a heritable basis for supraventricular tachycardias, but the genetic determinants and molecular mechanisms of these arrhythmias are poorly understood. We sought to identify genetic loci associated with atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular accessory pathways or atrioventricular reciprocating tachycardia (AVAPs/AVRT). We performed multiancestry meta-analyses of genome-wide association studies to identify genetic loci for AVNRT (4 studies) and AVAP/AVRT (7 studies). We assessed evidence supporting the potential causal effects of candidate genes by analyzing relations between associated variants and cardiac gene expression, performing transcriptome-wide analyses, and examining prior genome-wide association studies. Analyses comprised 2384 AVNRT cases and 106 489 referents, and 2811 AVAP/AVRT cases and 1,483 093 referents. We identified 2 significant loci for AVNRT, which implicate NKX2-5 and TTN as disease susceptibility genes. A transcriptome-wide association analysis supported an association between reduced predicted cardiac expression of NKX2-5 and AVNRT. We identified 3 significant loci for AVAP/AVRT, which implicate SCN5A, SCN10A, and TTN/CCDC141. Variant associations at several loci have been previously reported for cardiac phenotypes, including atrial fibrillation, stroke, Brugada syndrome, and electrocardiographic intervals. Our findings highlight gene regions associated with ion channel function (AVAP/AVRT), as well as cardiac development and the sarcomere (AVAP/AVRT and AVNRT) as important potential effectors of supraventricular tachycardia susceptibility.

Comparative utility of omnipolar and bipolar electroanatomic mapping methods to detect and localize dual nodal substrate in patients with atrioventricular nodal reentrant tachycardia.

Catheter-based slow pathway modification (SPM) for atrioventricular nodal reentrant tachycardia (AVNRT) is traditionally performed at empiric sites using anatomical landmarks and test ablation feedback within the triangle of Koch (TK). While studies have described more tailored techniques such as bipolar low voltage bridge (LVB) and wavefront collision identification, few have systematically compared the diagnostic yields of each and none have investigated whether omnipolar mapping technology provides incremental benefit. The objective of this study was to compare the utility of omnipolar andbipolar-derived qualitative and quantitative measurements in identifying and localizing dual AVN substrate in patients with versus without AVNRT. A retrospective case-control study of consecutive patients with paroxysmal supraventricular tachycardia undergoing electrophysiology study with both omnipolar and bipolar mapping from 2022-2023. Thirteen AVNRT cases (median age 16.1 years, 512 TK points) were compared to nine non-AVNRT controls (median age 15.7 years, 332 TK points). Among qualitative variables, an omnipolar activation vector pivot, defined as a ≥45 degree change in activation direction within the TK, had the highest positive (81%) and negative predictive values (100%) for identifying AVNRT cases and had a median distance of 1 mm from SPM sites. Among quantitative variables, the optimal discriminatory performance for successful SPM sites was observed using bipolar voltage restricted to a peak frequency >340 Hz (c statistic 0.75). Omnipolar vector pivot analysis represents an automated, annotation-independent qualitative technique that is sensitive and specific for AVNRT substrate and co-localizes with successful SPM sites. Bipolar voltage quantitatively describes SP anisotropy better than omnipolar voltage, and the addition of peak frequency signal analysis further optimizes the selection of SPM sites.

The optimal slow pathway ablation site in atrioventricular nodal reentrant tachycardia cases with an inferiorly located His bundle.

The optimal slow pathway (SP) ablation site in cases with an inferiorly located His bundle (HIS) remains unclear. In 45 patients with atrioventricular nodal reentrant tachycardia, the relationship between the HIS location and successful SP ablation site was assessed in electroanatomical maps. We assessed the location of the SP ablation site relative to the bottom of the coronary sinus ostium in the superior-to-inferior (SPSI), anterior-to-posterior (SPAP), and right-to-left (SPRL) directions. The HIS location was assessed in the same manner. The HIS location in the superior-to-inferior direction (HISSI), SPSI, SPAP, and SPRL were 17.7±6.4, 1.7±6.4, 13.6±12.3, and -1.0±13.0mm, respectively. The HISSI was positively correlated with SPSI (R2=0.62; P<.01) and SPAP (R2=0.22; P<.01), whereas it was not correlated with SPRL (R2=0.01; P=.65). The distance between the HIS and SP ablation site was 17.7±6.4mm and was not affected by the location of HIS. The ratio of the amplitudes of atrial and ventricular potential recorded at the SP ablation site did not differ between the high HIS group (HISSI≥13mm) and low HIS group (HISSI<13mm) (0.10±0.06vs. 0.10±0.06; P=.38). In cases with an inferiorly located HIS, SP ablation should be performed at a lower and more posterior site than in typical cases.

Upper common pathway analysis using late atrial premature depolarization in atrioventricular nodal reentry tachycardia

BackgroundAnatomic and electrophysiologic findings suggest that the actual circuit of atrioventricular nodal reentrant tachycardia (AVNRT) involves the perinodal atrium. However, occasional instances in which the atrium is dissociated from the AVNRT have led to the concept of an upper common pathway (UCP). ObjectiveWe aimed to assess the prevalence of UCP in AVNRT using a late atrial premature depolarization (LAPD) maneuver. MethodsPatients who were diagnosed with typical AVNRT by electrophysiologic studies were enrolled. For evaluation of the presence of UCP, an LAPD was given at the coronary sinus ostium (osCS) during AVNRT, and then pacing was repeated incrementally every 10 ms. Electrograms in the earliest retrograde atrial activation site (ERAS) near the proximal His were mapped and recorded during the pacing. Results were interpreted as follows: absence of UCP—an LAPD from the osCS can reset the tachycardia without depolarizing the ERAS; presence of UCP—an LAPD from the osCS can depolarize the ERAS without resetting the tachycardia; and indeterminate—an LAPD from the osCS either resets the ERAS and tachycardia simultaneously or does not reset both. ResultsThe LAPD maneuver was performed in 126 patients with AVNRT. It demonstrated an absence of UCP in 121 (96.0%) patients and the presence of UCP in 3 (2.4%) patients; the result was indeterminate in 2 (1.6%) patients. ConclusionThe LAPD maneuver revealed that the presence of UCP is indicated in only rare cases of AVNRT. In most AVNRT cases, the atrium is involved in the reentry circuit.

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

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

A novel approach to typical atrioventricular nodal reentrant tachycardia with high-resolution mapping using the CARTO 3 cardiac mapping system.

We hypothesized that high-resolution activation mapping during sinus rhythm (SR) in Koch's triangle (KT) can be used to describe the most delayed atrial potential around the atrioventricular node and evaluated whether ablation targeting of this potential is safe and effective for the treatment of patients with typical atrioventricular nodal reentrant tachycardia (AVNRT). We conducted a prospective, non-randomized, observational study using high-resolution activation mapping from the sinus node to KT with a PENTARAY or OCTARAY catheter using the CARTO 3 cardiac mapping system (Biosense Webster) during SR in 62 consecutive patients (22 men; age [mean ± standard deviation] = 55 ± 14 years) treated for typical AVNRT at our institution from August 2021 to March 2023. In all cases, the most delayed atrial potential was observed near the His potential within KT. Ablation targeting of this potential helped successfully treat each case of AVNRT, with a junctional rhythm observed at the ablation site. Initial ablation was deemed successful in 55/62 patients (89%); in the remaining seven patients, lesion expansion resolved AVNRT. One procedural complication occurred, namely, a transient atrioventricular block lasting 45 s. One patient experienced a transient tachycardic episode by the 1-month follow-up, but no further episodes were noted up to the 1-year follow-up. Activation mapping at KT during SR with the high-resolution CARTO system clearly revealed the most delayed atrial potential near the His potential within KT. Targeting this potential was a safe and effective treatment method for patients with typical AVNRT in our study.

PO-05-146 AN UNUSUAL ATRIOVENTRICULAR REENTRY TACHYCARDIA: SUCCESSFUL ABLATION OF NOVEL SLOW PATHWAY AT SUPERIOR SEPTAL PERIMITRAL LEFT ATRIUM

Atrioventricular nodal reentrant tachycardia (AVNRT) is a common supraventricular tachycardia (SVT), treated with catheter ablation of slow pathway. The right and left inferior slow pathway (SP) extensions of the AV node are widely recognized, but other SPs are very rare. We present a case of atypical AVNRT that was successfully ablated at the superior septal perimitral left atrium. N/A A 75-year-old man with history of coronary artery disease status post coronary artery bypass grafting and recurrent episodes of symptomatic SVT despite diltiazem and metoprolol presented for catheter ablation. Mid RP SVT (cycle length, CL 350 ms) with concentric atrial activation was inducible with atrial and ventricular extrastimulation. Synchronized premature ventricular complexes and ventricular entrainment excluded AV reentry. Very late coupled premature atrial complex from coronary sinus (CS) delivered synchronous to septal A activation delayed next A and reset SVT indicating AVNRT and excluding ectopic junctional (JT) or atrial tachycardia (AT). Further, AH interval during SVT was much longer than AH with atrial pacing at same CL excluding AT. We concluded mechanism to be atypical AVNRT. On activation mapping of right atrium, earliest A was recorded in the fast pathway region, earlier than locations of right and left slow pathways in the triangle of Koch and CS respectively. Radiofrequency ablation lesions anatomically targeting both slow pathways were delivered at base of triangle of Koch and inside CS without affecting SVT. High density activation maps of both right and left atria were created during SVT using Orion basket catheter and Rhythmia (Boston Scientific) mapping system. Earliest A was recorded in the superior septal perimitral left atrium, superior to the location of His bundle electrogram, and anatomically adjacent to aortic sinuses of Valsalva (not mapped). We concluded this to be an unusual left superior extension of the AV node. Radiofrequency ablation lesion using IntellaNav MiFi catheter at this site promptly terminated SVT. Consolidation lesions were delivered and anchored to the mitral annulus. The tachycardia was no longer inducible on programmed electrical stimulation despite isoproterenol. The patient has remained symptom free for 6 months since ablation. With activation mapping we identified the retrograde slow pathway participating in an unusual atypical AVNRT at superior septal perimitral left atrium.

Diagnostic utility of early premature ventricular complexes in differentiating atrioventricular reentrant and atrioventricular nodal reentrant tachycardias.

His-refractory premature ventricular complexes perturbing a supraventricular tachycardia (SVT) establish the presence of an accessory pathway (AP). Earlier premature ventricular complexes (ErPVCs) may perturb SVTs but are considered nondiagnostic. The purpose of this study was to test the hypothesis that an ErPVC will always show a difference >35 ms in its advancement of the next atrial activation during atrioventricular nodal reentrant tachycardia (AVNRT). During atrioventricular reentrant tachycardia (AVRT), a PVC delivered close to the circuit can result in greater advancement of atrial activation due to retrograde conduction via an AP. Thus, an AP response, defined as ErPVC (H1S2) advancing the subsequent atrial activation (A1-A2) more than this minimum difference (A1A2 ≤ H1S2+35 ms), establishes the presence of an AP. Sixty-five consecutive patients with SVT were retrospectively evaluated. ErPVCs were defined when the ventricular pacing stimulus was >35 ms ahead of the His during tachycardia. Among the 65 cases, 43 were AVNRT and 22 AVRT. Fourteen AVRT cases had an AP response with a mean H1S2+35 ms of 336 ± 58 ms and A1A2 of 309 ± 51ms. No AVNRT cases had an AP response. The specificity of an AP response to ErPVC in predicting AVRT was 100%. An AP response to PVCs (A1A2 ≤ H1S2+35 ms) is 100% specific for the presence of an AP.

High-definition electro-anatomical mapping of Koch’s Triangle including AV node potentials recordings in consecutive AVNRT patients

Abstract Funding Acknowledgements Type of funding sources: None. Background Activation mapping of Koch’s Triangle, even when coupled with high density mapping, is incomplete without recordings of AV nodal electrical activity. Purpose To identify, through a highly specific methodology and high-density electro-anatomical mapping (HDM), the slow AVN potential (AVNP) and the precise activation modality of Koch’s Triangle in SR in atrio-ventricular nodal reentrant tachycardia (AVNRT) patients. Method The 3D KT geometry was created from the Orion mapping and the Rhythmia Mapping System. KT was divided into 8 distinct regions moving from an antero-septal to postero-septal areas and bounded by tricuspid annulus (TA) anteriorly and tendon of Todaro posteriorly. AV nodal potential activity was recorded by non-standard bipolar electrogram filtering at 0.50–300 Hz. The AVNP was defined as a slow frequency potential between atrial and ventricular EGM similar to that reported by Scherlag and Jackman, and it was confirmed by high frequency atrial pacing. The AVNP was annotated at the end of electrogram when it was followed in the same recording by a sharp potential; otherwise it was annotated at the center. Data are reported as mean±SD. Results Twenty successful SP ablation cases of typical AVNRT from 7 centers were included. RA acquired points during SR were 2512±1400 (123±67 acquired inside the KT, KT area of 41±64 mm2). The time of a complete RA mapping was 19.2±8 min. The AVNP was detected in all cases (n=20, 100%). At the mid-region of the KT, AVNP was identified in 20 (100%) cases; at postero-septal regions bounded anteriorly by the TA and posteriorly by the lateral wall toward the crista terminalis AVN was present in 17 (85%) cases; at mid-postero-septal regions AVN was detected in 15 (75%) cases. In all patients, the first activation in the KT was recorded in the antero-septal region at the expected site of the fast pathway; then the wavefront spread in two directions: anteriorly toward the His-bundle and posteriorly toward the base of KT colliding with the wavefront coming from the opposite direction through the slow pathway. In all patients, abolition of the SP and acute procedural success was achieved in the first procedure with 5.4±3 RF ablations. In 30 out 35 (86%) ablation sites, ablations were done at sites with concurrent detectable AVNP. No complications occurred. Conclusions High-density mapping using a non-standard bipolar electrograms filtering at 0.50–300 Hz showed multiple electrograms in SR including low frequency potential that may represent the electrical activity of compact node and inferior extensions.

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.

Catheter ablation via the left atrium for atrioventricular nodal reentrant tachycardia: A narrative review.

BackgroundSince 1996, it has been recognized that catheter ablation for atrioventricular nodal reentrant tachycardia (AVNRT) may require an approach through the left atrium.ObjectiveThe purposes are to present a case report and to provide a comprehensive narrative review on this topic.MethodsA literature review of all articles that provided detailed information on patients who underwent catheter ablation via the left atrium for AVNRT was performed. The primary search queried PubMed using Medical Subject Headings (MeSH) terms “atrioventricular nodal reentrant tachycardia” and “left.” The secondary search was performed by manual review of reference lists and Google Scholar citations of manuscripts retrieved by the primary search. The review was limited to the English language.ResultsThe searches yielded 30 articles that described 79 patients. A case report was added. Therefore, the final review consisted of 80 patients. The prevalence of left atrial ablation for patients with AVNRT undergoing catheter ablation at tertiary care centers was approximately 1%. Failed right atrial ablation, with or without coronary sinus ablation, was the most common indication for left atrial ablation. Pooled data from 3 cohort studies estimated the acute success rate for radiofrequency ablation of the slow pathway at the septal or inferoparaseptal segments of the mitral valve annulus after failed right-sided ablation to be 90%. There were no reports of atrioventricular block requiring permanent pacemaker implantation.ConclusionCatheter ablation of the slow pathway via the left atrium is an important technique for AVNRT cases that are refractory to conventional ablation.

Mechanism and interpretation of two-for-one response to premature atrial complexes during atrioventricular node re-entry tachycardia.

The response to premature atrial complexes (PACs) during tachycardia has been shown to differentiate atrioventricular nodal re-entrant tachycardia (AVNRT) from focal junctional tachycardia (JT). His refractory PAC (HrPACs) perturbing the next His (resetting with fusion) is diagnostic of AVNRT and such a late PAC fusing with the native beat cannot reset the focal source of JT. Early PAC advancing the immediate His with continuation of tachycardia suggests JT but can also occur in AVNRT due to simultaneous conduction through the AV nodal fast and slow pathways [two-for-one response (TFOR)]. The objective of this study was to evaluate the incidence and mechanism of TFOR after early premature atrial complexes (ePACs) during AVNRT and to differentiate it from the known response to ePACs during JT. Typical AVNRT cases were diagnosed using standard criteria. We evaluated the responses to scanning PACs delivered during tachycardia in 100 patients undergoing AV node slow pathway modification for AVNRT. The responses to HrPACs and ePACs delivered from coronary sinus os or high right atrium were retrospectively reviewed. In 10 patients, ePACs advanced the immediate His with continuation of tachycardia. In all 10 cases, HrPACs advanced the next His, confirming AVNRT as the mechanism, and indicating a TFOR. A TFOR can occur in a small number of patients during AVNRT and is therefore not diagnostic of JT. However, HrPACs always perturbed the next His in these cases, confirming the diagnosis of AVNRT and allowing for differentiation from JT.

Left sided ablation for Atrioventricular Nodal Re-entrant Tachycardia: Frequency, Characteristics and Outcomes.

BackgroundLeft-sided ablation, targeting left inferior AV nodal extensions, is thought to be necessary for success in a small proportion of atrioventricular nodal re-entrant tachycardia (AVNRT) ablations; however Indian data are scarce in this regard.MethodsConsecutive cases of AVNRT undergoing slow pathway ablation in a single centre over an 18-month period were retrospectively analyzed. Left-sided ablation at the posteroseptal mitral annulus was performed if right-sided ablation failed to abolish AVNRT.ResultsFrom January 2017 to June 2018, out of 215 consecutive supraventricular tachycardia (SVT) cases, 154 (71.6%) were AVNRT (47.1 ± 13.1 years, 46.1% male). Trans-septal ablation was required in 5 (3.2%) cases (mean age 48.8 ± 9.4 years; 4 female, 1 male); all with typical (slow-fast) form of AVNRT. Compared with cases needing only right-sided ablation, radiofrequency time (50.8 ± 16.9 vs. 9.9 ± 8.5 min; p = 0.005) and procedure time (166.0 ± 35.0 vs 79.6 ± 35.9 min; p = 0.004) were significantly longer for trans-septal cases, while baseline intervals and tachycardia cycle length were not significantly different. Junctional ectopy was seen in only 2 of the 5 cases during left-sided ablation, but acute success (non-inducibility) was obtained in 3 cases. There were no instances of AV block. Over mean follow-up of 12.2 ± 4.0 months, clinical recurrence of AVNRT occurred in one case, while others remained arrhythmia-free without medication.ConclusionLeft-sided ablation was required in a small proportion of AVNRT ablations. Trans-septal approach targeting the posteroseptal mitral annulus was safe and yielded good mid-term clinical success.

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

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). Diagnosing sustained supraventricular tachycardia (SVT) despite the occurrence of ventriculoatrial block (VAB) is challenging. 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). 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≤125ms (PPV: 100%; NPV: 100%) characterized NV-ORT. 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≤125ms discriminating NV-ORT from NF-ORT and AVNRT.

P1005Origin, distribution and timing of the slow pathway potentials recorded inside the Kock's triangle in Avnrt patients through High-density Mapping

Abstract Background Atrial activation during typical atrioventricular nodal reentrant tachycardia (AVNRT) exhibits anatomic variability and spatially heterogeneous propagation inside the Kock's Triangle (KT). The mechanism of the reentrant circuit has not been elucidated yet. Purpose To evaluate signal characteristics and find out the origin, distribution, and timing of the slow pathway (SP) potentials recorded in the KT. Methods The 3-D KT geometry was created during both sinus rhythm (SR) and tachycardia (TR) from the basket mapping catheter IntellaMap Orion and the Rhythmia Mapping System (Boston Scientific). The KT was divided into 8 regions moving from an antero-septal to postero-septal areas and bounded by tricuspid annulus (TA) anteriorly and tendon of Todaro (TT) posteriorly. Each area was characterized in terms of distribution and timing of Jackman (JP) and Haissaguerre (HP) potentials and signal amplitude. Results 20 consecutive successful SP ablation cases of AVNRT were included (mean RA acquired points = 6000±1100, 275±63 inside the KT; mean KT area=29±3mm2; mean mapping time=12±5 minutes). During SR, the site of earliest atrial activation within the KT was anterior in 80% of patients whereas a midseptal activation occurred less frequently (20%). The mid-septal regions bounded by TA anteriorly and TT posteriorly showed higher prevalence of JP as compared to antero-/mid-septal regions across TT both in SR and TR (77.4% vs 4.8% during SR, p&lt;0.0001; 84.1% vs 0% during TR, p&lt;0.0001, respectively). HPs seemed to have variable distribution across KT (50% of these potentials recorded in antero- to mid-septal regions across TT for SR, 52.3% for TR). The median signal voltage was 0.44 [0.2–0.9] mV during SR and 0.5 [0.22–0.895] mV during TR. The mid-septal region was the area of lowest voltage compared to other regions (0.2 [0.1–0.7] mV vs 0.5 [0.4–1.5] mV for SR, p&lt;0.0001; 0.2 [0.15–0.6] mV vs 0.6 [0.4–1.5] mV for TR, p&lt;0.0001, respectively). Conclusion JPs seem to be associated with low signal-amplitude areas whereas HPs seem to have variable distribution across KT. Although not perfectly known, the typical low-high-type double potential of JP might be therefore explained by wavefront collision in the lowest area of the KT. Acknowledgement/Funding None

Atrioventricular Nodal Reentrant Tachycardia Triggered by Marijuana Use: A Case Report and Review of the Literature.

Marijuana is the most commonly abused recreational substance. With the increasing legalization of marijuana, its use is expected to rise. Delta-9-tetrahydrocannabinol (THC) is the psychotropic component of marijuana, acting via CB1 and CB2 G-protein coupled cannabinoid receptors. Marijuana has serious cardiovascular effects including tachycardia, orthostatic hypotension, angina and myocardial infarction to name a few. Previous reports by our group and others documented various arrhythmias other than atrioventricular nodal reentrant tachycardia (AVNRT) that are associated with marijuana use. In this report, we present a case of AVNRT associated with marijuana use. Marijuana in high doses stimulates parasympathetic nerves. While parasympathetic stimulation can increase the refractory period of the fast conduction pathway, it has no effect on the slow and retrograde pathways, therefore its use creates an ideal milieu for AVNRT initiation and maintenance. Our case report highlights the importance of including marijuana use in the differential diagnosis, as a possible trigger, for patients presenting with AVNRT that is otherwise unexplainable.

A comparative analysis of clinical outcomes and disposable costs of different catheter ablation methods for the treatment of atrioventricular nodal reentrant tachycardia.

BackgroundCatheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) is a commonly performed electrophysiology (EP) procedure. Few data exist comparing conventional (CONV) versus novel ablation strategies from both clinical and direct cost perspectives. We sought to investigate the disposable costs and clinical outcomes associated with three different ablation methodologies used in the ablation of AVNRT.MethodsWe performed a retrospective review of AVNRT ablations performed at Augusta University Medical Center from 2006 to 2014. A total of 183 patients were identified. Three different ablation techniques were compared: CONV manual radiofrequency (RF) (n=60), remote magnetic navigation (RMN)-guided RF (n=67), and cryoablation (CRYO) (n=56).ResultsBaseline demographics did not differ between the three groups except for a higher prevalence of cardiomyopathy in the RMN group (p<0.01). The clinical end point of interest was recurrent AVNRT following the index ablation procedure. A significantly higher number of recurrent AVNRT cases occurred in the CRYO group as compared to CONV and RMN (p=0.003; OR =7.75) groups. Cost-benefit analysis showed both CONV and RMN to be dominant compared to CRYO. Cost-minimization analysis demonstrated the least expensive ablation method to be CONV (mean disposable catheter cost = CONV US$2340; CRYO US$3515; RMN US$5190). Despite comparable clinical outcomes, the incremental cost of RMN over CONV averaged US$3094 per procedure.ConclusionAVNRT ablation using either CONV or RMN techniques is equally effective and associated with lower AVNRT recurrence rates than CRYO. CONV ablation carries significant disposable cost savings as compared to RMN, despite similar efficacy.

Familial atrioventricular nodal re-entrant tachycardia: A case seriers and a systematic review

Multiple reports of familial clustering suggest that genetic factors may contribute in the pathogenesis of atrioventricular nodal re-entrant tachycardia (AVNRT). We report three cases of AVNRT in a father and his two sons along with a review of literature of other similar cases. Electrophysiological studies induced typical AVNRT, which was successfully eliminated by radiofrequency ablation in all of them. Of the 22 reported cases, 96% had typical (slow-fast) variant of AVNRT. The predominant pattern of inheritance appears to be autosomal dominant, though other patterns may exist. Further research is needed to understand the genetic influence of AVNRT and its pathophysiology.

Radiofrequency catheter ablation therapy used in 123 children with drug-refractory tachycardia arrhythmias

Objective To evaluate the safety and efficacy of radiofrequency catheter ablation (RFCA) in children with tachycardia arrhythmias. Methods One hundred and twenty-three children under 3 years old with drug-refractory tachycardia underwent an interventional electrophysiology procedure and RFCA in Medical Center of Tsinghua University from April 1994 to December 2014, including 98 male and 25 female, and their average age was (22.9±9.6) months(2-35 months) and body weight was (13.64±2.80) kg(4.66-19.40 kg). The mechanism, RFCA methods, the success rate, recurrence rate and complication rate of the different types of tachycardia were investigated. Results Among these children, interventional electrophysiological study confirmed 94 cases (76.4%, 94/123 cases) with atrioventricular reentrant tachycardia (AVRT), 7 cases(5.7%, 7/123 cases) with atrioventricular nodal reentrant tachycardia (AVNRT), 3 cases (2.4%, 3/123 cases) with focal atrial tachycardia (FAT), 8 cases (6.5%, 8/123 cases) with atrial flutter (AF), 5 cases (4.1%, 5/123 cases) with idiopathic left ventricular tachycardia (ILVT), 6 cases (4.8%, 6/123 cases) arrhythmia was not induced.RFCA was performed in 109 cases (88.6%, 109/123 cases). The success rate of RFCA was 94.5%(103/109 cases) and the recurrence rate was 6.8% (7/103 cases). In 88 cases of AVRT, the success rate was 96.6%(85/88 cases), and the recurrence rate was 8.2%(7/85 cases). In 5 cases of AVNRT, the success rate was 100.0%(5/5 cases). In 3 cases of FAT, the success rate was 33.3%(1/3 cases). In 8 cases of AF, the success rate was 87.5%(7/8 cases). In 5 cases of ILVT, the success rate was 100.0%(5/5 cases), and there was no recurrence.The complication of RFCA was puncture vascular occlusion in 2 cases (1.6%, 2/123 cases), without other serious complications and death cases.In this group of children, the fluoroscopy exposure time was (11.2±5.8) min(5.7-18.2 min) and dose area product(DAP) exposure was (954.5±117.4) mGy×cm2(707-2 201 mGy×cm2). Compared with the elder children (379 cases over 3 years old) of the exposure fluoroscopy time(10.8±6.4) min(3.9-20.5 min) and DAP exposure (927.5±193.4) mGy×cm2(439-3 201 mGy×cm2), there was no statistically significant difference(t=0.616, 1.463, all P>0.05). Conclusions AVRT was the most common type of arrhythmia in infants and a higher incidence of multiple accessory pathways was found in infants.Application of radiofrequency ablation to children with tachycardia arrhythmias can be relatively safe and effective to the infants with drug-resistant tachycardia. Key words: Tachycardia arrhythmia; Radiofrequency catheter ablation; Infant

Review of Outcomes of Eighty-two cases of Typical AVNRT after Radiofrequency Ablation at Madras Medical Mission, India

Context: Diagnoses of supraventricular arrhythmias often depend on combination of varied features of baseline electrophysiology, tachycardia and responses to pacing manoeuvres. These investigations are carried out regularly at the Cardiac Catheterization Laboratory of Madras Medical Mission, India. Aims: The purpose of this study was to describe the initial outcome following cardiac electrophysiologic studies and radiofrequency ablation of typical atrio-ventricular nodal re-entrant tachycardia (AVNRT). Settings and Design: This retrospective study was carried out in the Cardiac Electrophysiology Department, of the Institute of Cardiovascular Diseases, Madras Medical Mission, India. Subjects and Methods: Records of consecutive cases of typical AVNRT following cardiac electrophysiologic studies and radiofrequency ablation carried out between May 2013 to April 2014 were reviewed. Eighty-two cases were chosen for analysis. Statistical analysis used: The data obtained were analysed using SPSS statistical software version 15. Results: The 82 patients comprised 24 males and 58 females. Dual nodal physiology was documented in 79 (96.3%), A simultaneous V and A (VA interval Conclusions: Treatment of typical AVNRT by radiofrequency cardiac catheter ablation at the Madras Medical Mission is highly effective and safe.