Atypical Atrioventricular Nodal Reentry Tachycardia with Atrioventricular Block Mimicking Atrial Tachycardia:

AVNRT Mimicking Atrial Tachycardia, Introduction : Fast-intermediate form AV nodal reentry tachycardia (AVNRT) sometimes may mimic atrial tachycardia or atrial flutter and render the diagnosis difficult when the tachycardia rate is fast and AV block occurs during tachycardia.
Methods and Results : A 45-year-old woman with paroxysmal supraventricular tachycardia was referred to this institution. Initially, the tachycardia was thought to be an atrial tachycardia because of: (1) a short cycle length of the tachycardia with 2:1 and Wenckebach AV block; (2) a difference in the atrial activation sequence during tachycardia and during ventricular pacing; and (3) failure of burst ventricular pacing to affect the atrial rate and the atrial activation sequence during tachycardia. An accurate diagnosis of fast-intermediate form AVNRT was subsequently made based on the finding that the tachycardia was induced following delivery of a third ventricular extrastimulus, which showed a sequence of V-A-H and a change on atrial activation sequence of the induced beat. Successful radiofrequency ablation was achieved only after accurate diagnosis of the tachycardia was made.
Conclusion : Fast-intermediate form AVNRT sometimes may masquerade as atrial tachycardia. Accurate diagnosis is mandatory for successful ablation therapy.     

射频消融疑难的房室结折返性心动过速(附三例分析)

回顾分析２２４例房室结折返性心动过速的射频消融结果，３例消融未成功，占１．３％。其中１例消融房室结造成Ⅲ度房室阻滞后仍有心动过速发作，提示房室结双径路下部共同通道的存在。消融不成功的原因可能为慢径不是一组纤维，且在解剖上快、慢径极为邻近，易同时受损。提示在遇到消融极为困难的病例，应酌情放弃消融，考虑更恰当的治疗方式，以避免因刻意追求消融成功而导致永久性房室阻滞的发生。     

Pathological Findings Following Slow Pathway Ablation for AV Nodal Reentrant Tachycardia

Pathology of Slow Pathway Ablation. Introduction : AV nodal reentrant tachycardia is routinely cured using radiofrequency catheter ablation techniques. However, there remains controversy as to whether the reentrant circuit for this tachycardia exists solely in the AV node or whether perinodal atrial tissues are vital to the circuit. In addition, the effects of radiofrequency ablation of the slow pathway of AV nodal reentrant tachycardia on the AV node are not known. We examined an autopsy specimen to determine the anatomical location and extent of AV nodal damage of radiofrequency slow pathway ablation for cure of AV nodal reentrant tachycardia.
Methods and Results : A 64-year-old woman with confirmed AV nodal reentrant tachycardia underwent a successful "slow pathway" AV modification with a single radiofrequency application. Five months after the procedure, the patient died from a spontaneous intracranial hemorrhage. Postmortem gross pathological examination of the heart was performed. The heart was then sectioned and stained for histologic examination. On gross examination, a pale lesion 0.5 cm in diameter was seen on the endocardial surface adjacent to the tricuspid annulus. approximately 0.85 cm anterior to the coronary sinus os and 1.15 cm from the apex of the triangle of Koch where the AV node resides. Histologic examination revealed a right atrial lesion composed of connective tissue and fat. The compact AV node and surrounding transitional cells were unaffected histologically, with normal atrial cells lying between the AV node and the lesion.
Conclusion : Ablation of the slow pathway to cure AV nodal reentrant tachycardia does not produce any gross or histologic damage to the AV node, suggesting that the AV nodal reentrant circuit does not exist in its entirety in the AV node.     

Radiofrequency Modification for Inducible and Suspected Pediatric Atrioventricular Nodal Reentry Tachycardia

Introduction: AV Node Reentry Tachycardia (AVNRT) is the second most common supraventricular tachycardia (SVT) undergoing pediatric radiofrequency ablation behind accessory pathway reentry tachycardias. AVNRT can be difficult to induce during electrophysiology study (EPS) and dual atrioventricular nodal (AVN) pathways physiology may not be demonstrated in young patients.Purpose: This report is the largest single center long term pediatric experience of radiofrequency modification of slow AVN input fibers for inducible or suspected (non-inducible) AVNRT.Results: One hundred thirty-two patients underwent slow input AVN modification from 1993 to 2002. The mean patient age was 13.7 years (4–20 yrs) with 62M/70F. Outpatient tachycardia was documented by ambulatory monitoring in all patients. AVNRT was induced in 98/132 patients during EPS (group A) with mean SVT cycle length of 324 msec (230–570 msec). Initial AVN modification (group A) was successful in 97/98 patients (99%). During 34/132 EPS, AVNRT was non-inducible; dual AVN physiology was present in 19/34 (group B), and 15/34 did not show evidence for dual AVN physiology (group C). These 34 patients underwent empiric AVN modification following discussion with patients’ families. Freedom of recurrence from SVT at 1 year was 96% for group A (94/98), 89% (17/19) for group B and 93% (14/15) for group C. 1 major and 6 minor complications occurred.Conclusions: AVN modification for AVNRT can be performed safely and effectively in pediatric patients with good long-term results. Empiric slow pathway AVN modification for non-inducible SVT results in a high rate of freedom from recurrence of tachycardia.     

Case Report: Radiofrequency Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia in a Patient with Heart Transplantation

Ten years after orthotopic cardiac transplantation, a 56-year-old man developed recurrent presyncope and syncope. A 24-hour ambulatory electrocardiographic recording did not document significant arrhythmic events. A head-up tilt table test was negative. An electrophysiologic study revealed dual atrioventricular (AV) nodal physiology and inducible typical atrioventricular nodal reentrant tachycardia (AVNRT). The patient became hypotensive and presyncopal during AVNRT. Radiofrequency (RF) catheter ablation successfully eliminated AVNRT without complications. The patient remained free of symptoms at nine months follow-up.     

Radiofrequency Catheter Ablation of Atrioventricular Nodal Reentrant Tachycardia after Orthotopic Heart Transplantation

Patients with orthotopic heart transplantation may develop a variety of arrhythmias. Successful radiofrequency catheter ablation for tachyarrhythmias from manifest and concealed accessory bypass tracts in transplant patients has been previously reported. We present a patient with orthotopic heart transplantation who developed typical atrioventricular nodal tachycardia, which was successfully treated by radiofrequency catheter ablation.     

Radiofrequency Catheter Ablation of AtypicalAtrioventricular Nodal Reentrant Tachycardia

Ablation of Atypical Atrioventricular Nodal Reentrant Tachycardia, Introduction: Published reports of radiofrequency ablation of atypical atrioventricular nodal reentranttacbycardia (AVNRT) have been limited. We present our experience in 10 consecutive patientswith atypical AVNRT wbo underwent radiofrequency ablation of the "slow" AV nodal pathway.
Methods and Resttlts: there were 9 females and 1 male; their mean age was 44 ± 19 years (± SD), the mean AVNRT cycle length and ventriculoatrial (VA) interval at the His positionduring AVNRT were 340 ± 50 msec and 200 ± 70 msec, respectively. the slow pathway wassuccessfully ablated in all patients with a mean of 10 ± 7 radiofrequency energy applications inthe posteroseptal right atritim near the coronary sinus os. The mean procedure duration was 100 ± 35 minutes. There were no complications. In 4 patients, target sites were identified during sinus rhythm by mapping for possible slow pathway potentials, In the other 6 patients, target sites were identified by mapping retrograde atrial activation during AVNRT or ventricularpacing, The VA times at successful target sites were a mean of 45 ± 30 msec less tban the VAtime at the His cathetcr during AVNRT, There were no differences in success rate, number ofradiofrequency energy applications, or procedure duration between patients in whom mappingwas guided by possible slow pathway potentials or by retrograde atrial activation, During 6 ± 3 months of followup, 1 patient bad a recurrence of atypical AVNRT and underwent a secondablation procedure, which was successful.
Conclusion: Radiofrequency ablation of atypical AVNRT can be safely and effectivelyaccomplisbed when target sites are identified based either on possible slow pathway potentialsduring sinus rbytbm or retrograde atrial activation times during tachycardia.     

Atrioventricular Nodal Reentrant Tachycardia with Multiple Discontinuities in the Atrioventricular Node Conduction Curve: Immediate Success Rates of Radiofrequency Ablation and Long-Term Clinical Follow-up Results as Compared to Patients with Single or No AH-Jumps

Background: Some patients with atrioventricular nodal reentrant tachycardia (AVNRT) demonstrate multiple discontinuities (AH jump) in their antegrade AV node conduction curves. We evaluated and compared the immediate success rates, procedure-related complications, long-term clinical follow-up results and recurrence rates after slow pathway ablation in patients with multiple versus single or no AH jumps. Methods: The study group consists of 278 consecutive patients (mean age 36.6 ± 15.7) who underwent ablation for typical AVNRT, divided into three categories according to the number of AH jumps (50 ms) before ablation: Group-1 consisted of 63 patients (23%) with continuous AV node function curves; Group-2 of 183 patients (66%) with a single jump and Group-3 of 32 (12%) patients showing more than one AH jumps. Results: Age was significantly higher in Group-3 as compared to Group-1 (43 ± 18 years vs. 34 ± 16 years, p = 0.020). The electrophysiological features of AVNRT did not differ among groups. Before ablation, the maximum AH interval was significantly longer in Group-3 as compared to Groups-1 and -2 (p < 0.001 for both). AV node antegrade ERP was significantly shorter in Group-3 than in Group-2, both before and after ablation (p < 0.050 for both). AV node Wenckebach cycle length (WCL) was shorter in Group-3 as compared to both Groups-1 and -2, before and after ablation (p < 0.050 for all). AV node WCL was prolonged significantly in all groups after ablation (p < 0.001 for all). Residual dual pathways were present in 37 of 278 patients (13%) after ablation and were significantly more frequent in Group-3 than Group-2 (31% vs. 15%, p = 0.023). Conclusions: Patients with multiple AH jumps are older and more often have residual dual atrioventricular nodal pathway physiology after successful ablation but these features do not affect the immediate and long-term success rates of slow pathway ablation as compared to patients with single or no AH jumps.     

Atrioventricular Nodal Reentrant Tachycardia in Implantable Cardioverter Defibrillators: Diagnosis and Troubleshooting

Inappropriate therapies are frequent in patients with implantable cardioverter defibrillators (ICDs) and are associated with adverse outcomes, including increased mortality. Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common reentrant supraventricular tachycardia (SVT) and a cause of inappropriate therapies in these patients. In the present article we review the problem of AVNRT in ICD patients with a focus on diagnosis and the available algorithms to improve arrhythmia discrimination and prevent inappropriate shocks.     

Pseudo-Pacemaker Syndrome Following Inadvertent Fast Pathway Ablation for Atrioventricular Nodal Reentrant Tachycardia

Pseudo-Pacemaker Syndrome After AV Nodal Ablation. Atrioventricular nodal reentrant tachycardia that is refractory to drug treatment has recently been treated with radiofrequency catheter ablation. In this case report we describe a patient with atrioventricular nodal reentrant tachycardia in whom radiofrequency ablation of slow pathway was attempted, with inadvertent damage to the fast pathway. The patient developed marked first-degree atrioventricular block associated with symptoms mimicking pacemaker syndrome.     

The Utility of a Lewis Lead for Distinguishing Atrioventricular Reentrant Tachycardia from Typical Atrioventricular Nodal Reentrant Tachycardia

Objective The Lewis lead configuration is an alternative bipolar chest lead and it can help detect atrial activity. The utility of the Lewis lead to distinguish orthodromic atrioventricular reentrant tachycardia (AVRT) from typical atrioventricular nodal reentrant tachycardia (AVNRT) by visualizing the apparent retrogradely conducted P waves was investigated. Methods Forty-four patients with paroxysmal supraventricular tachycardia (PSVT) were included in this study. All patients had PSVT documented by an electrocardiogram (ECG) and underwent an electrophysiological study (EPS). During tachycardia, an ECG recording was performed using a Lewis lead with the electrode on the right aspect of the sternum at the second intercostal space instead of the right arm and the electrode on the fourth intercostal space instead of the left arm. The ECG parameters during tachycardia were compared between AVRT and AVNRT. Results Fourteen patients were diagnosed with AVRTs and 30 with typical AVNRTs on EPS. The positive P wave could be seen in the Lewis lead configuration in 9 of 14 patients with AVRTs and 21 of 30 patients with AVNRTs. P waves were more often visible in the Lewis lead configuration than in the standard leads (66% vs. 45%). The RP interval was significantly longer for AVRTs than for AVNRTs (88±17 vs. 154±34 ms, p<0.001), which yields 89% sensitivity and 71% specificity for distinguishing these 2 tachyarrhythmias with a cut-off point of 100 ms. Conclusion A Lewis lead configuration may help to make an accurate diagnosis among the reentrant supraventricular tachycardias prior to procedures, owing to its ability to locate P waves.     

Catheter Ablation for the Treatment of Paroxysmal Supraventricular Tachycardia

Catheter Ablation for PSVT. Radiofrequency catheter ablation has evolved into a front-line curative therapy for patients who have paroxysmal supraventricular tachycardia secondary to Wolff-Parkinson-White syndrome, AV nodal reentrant tachycardia, and atrial tachycardia. In patients with accessory pathways, cure rates exceed 90% in almost all anatomic locations. Equally high success rates are noted in patients with atriofascicular pathways and the permanent form of junctional reciprocating tachycardia. Complications secondary to catheter ablation of accessory pathways occur in 1% to 3% of patients and include cardiac perforation, tamponade, AV block, and stroke. In patients with AV nodal reentrant tachycardia, selective slow pathway ablation is curative in over 95% of patients with a very low risk of AV block. Atrial tachycardias originating in both the left and right atria can he successfully ablated in over 80% of patients. Given the overall effectiveness of this procedure, radiofrequency catheter ablation should be considered as front-line therapy in patients with recurrent or drug-refractory paroxysmal supraventricular tachycardia. Although an effective therapy, the risks and benefits of this procedure need to be assessed in all patients who are candidates for this procedure.     

Decremental Accessory Pathway Conduction After Ablation and Antidromic Atrioventricular Reciprocating Tachycardia 8 Years After Successful Radiofrequency Ablation

Introduction: This is a rare case of antidromic reciprocating tachycardia developing 8 years after successful catheter ablation.
Result: A 15-year-old girl had recurrence of palpitations 8 years after the ablation of manifest right posteroseptal accessory pathway. Atrial burst pacing revealed Wenckebach atrioventricular conduction with preexcitation. Wide QRS tachycardia with identical morphology to sinus rhythm associated with retrograde His potential recorded immediately after the V-wave was induced by isoproterenol infusion. Atrial premature stimulus applied at the identical timing of His potential advanced the subsequent ventricular beat and His potential.
Conclusion: Catheter ablation may produce decremental accessory pathway conduction and rarely cause antidromic atrioventricular reciprocating tachycardia. This may be explained by a presence of de novo accessory pathway with decremental conduction properties that became manifest after the first ablation.     

Electrophysiologic Spectrum of Atrioventricular Nodal Behavior in Patients with Atrioventricular Nodal Reentrant Tachycardia Undergoing Selective Fast or Slow Pathway Ablation

AV Nodal Behavior After Ablation. Introduction; The objective of this report is to delineate the atrioventricular (AV) nodal electrophysiologic behavior in patients undergoing fast or slow pathway ablation for control of their AV nodal reentrant tachycardia (AVNRT).
Methods and Results: One hundred sixteen consecutive patients with symptomatic AVNRT were included. Twenty-two patients underwent fast pathway ablation with complete abolition of AVNRT in all and development of complete AV block in five patients. Of 17 patients with intact AV conduction postablation, 12 had demonstrated antegrade dual pathway physiology during baseline study, which was maintained in three and lost in nine patients postablation. Two patients with successful fast pathway ablation developed uncommon AVNRT necessitating a slow pathway ablation. Twenty-one patients demonstrated both common and uncommon forms of AV nodal reentry during baseline study. The earliest site of atrial activation was close to the His-bundle recording site (anterior interatrial septum) during common variety and the coronary sinus ostium (posterior interatrial septum) during the uncommon AV nodal reentry in all 21 patients. Ninety-six patients underwent successful slow pathway ablation. Among these, the antegrade dual pathway physiology demonstrable during baseline study (60 patients) was maintained in 25 and lost in 35 patients postablation.
Conclusion: These data suggest that: (1) dual pathway physiology may persist after successful ablation, which might be a reflection of multiple reentrant pathways in patients with AVNRT: and (2) the retrograde pathways during common and uncommon AVNRT have anatomically separate atrial breakthroughs. These findings have important electrophysiologic implications regarding the prevailing concept of the AV nodal physiology in patients with AVNRT.     

Atrioventricular Nodal Reentry Tachycardia in Patients with Sinus Node Dysfunction: Electrophysiologic Characteristics, Clinical Presentation, and Results of Slow Pathway Ablation

AVNRT and Sinus Node Dysfunction. Introduction: Sinus node dysfunction (SND) is frequently associated with impaired AV conduction. This study investigated the electrophysiologic properties of dual AV nodal pathways in patients suffering from both SND and AV nodal reentrant tachycardia (AVNRT). Methods and Results: Two groups of patients with slow-fast AVNRT underwent invasive electrophysiologic testing and catheter ablation of the slow pathway. Group A comprised 10 patients with SND (age 70 ± 8 years), (Group B included 10 age-matched patients without SND (age 69 ± 7 years; P = NS) who served as controls. Patients of group A exhibited prolongation of the anterograde Wenckebach cycle lengths (WBCLs) of both the fast pathway (559 ± 96 vs 361 ± 38 msec; P < 0.01) and the slow pathway (409 ± 57 vs 339 ± 32 ms; P < 0.01). However, the delta between the WBCLs of the fast and the slow pathways was larger in patients of group A (150 ± 80 vs 22 ± 20 msec; P < 0.01). Retrograde fast pathway conduction was well preserved with no difference in WBCLs (356 ± 42 vs 330 ± 47 msec; P = NS). Cycle lengths of AVNRT were longer in group A (468 ± 46 vs 363 ± 37 msec; P < 0.01). Clinically, all patients of group A suffered from multiple episodes of AVNRT per week, which was not the case in any patient of group B (P < 0.01). Catheter ablation of the slow pathway eliminated AVNRT in all patients without complications. Conclusions: Patients with AVNRT and SND exhibit characteristic electrophysiologic alterations of both AV nodal pathways. Clinically, this results in significantly more frequent episodes of tachycardia. Slow pathway ablation appears to be safe and effective in these patients.     

Successful Ablation of a Nonreentrant Dual Atrioventricular Nodal Tachycardia

Selective radiofrequency catheter ablation of the slow pathway ofthe AV node has become the treatment of choice for AV nodal reentranttachycardia. We describe a case of a nonreentrant AV nodal tachycardia andits successful treatment by slow pathway ablation.     

Interruption of the Inferior Extension of the Compact Atrioventricular Node Underlies Successful Radio Frequency Ablation of Atrioventricular Nodal Reentrant Tachycardia

A recent anatomic study has revived interest in the inferior extensions of the compact atrioventricular node in humans. The rightward extension is on the right atrial aspect, close to the septal attachment of the tricuspid valve leaflet and, hence, closely related to the anticipated slow pathway considered to play a role in atrioventricular nodal reentrant tachycardia (AVNRT). This report documents a patient, 65 years of age, with dilated cardiomyopathy and AVNRT. The tachycardia was successfully terminated using selective radiofrequency (RF) ablation, delivered at a site where a slow potential was recorded and validated by atrial pacing, located between the tricuspid valve and the os of the coronary sinus (CS), close to its superior rim. In subsequent years the patient developed progressive heart failure and eventually died. Histopathologic examination revealed extensive scar tissue at the site of the burn, extending onto the crest of the underlying ventricular septum. Serial sections revealed the compact AV node superiorly and an inferior extension surfacing from the scar which could be traced inferiorly beyond the os of the CS. This is the first documentation of RF ablation interrupting an inferior extension of the compact AV node in a patient successfully ablated for AVNRT. The observation suggests that the slow pathway in this patient found its anatomic substrate in the inferior extension of the compact AV node.     

Dimension and Related Anatomical Distance of Koch's Triangle in Patients with Atrioventricular Nodal Reentrant Tachycardia

Koch's Triangle in AVNRT. Introduction: The dimension of Koch's triangle in patients with AV nodal reentrant tachycardia has not been well described. Understanding the dimension and anatomical distance related to Koch's triangle might be useful in avoiding accidental AV block during ablation of the slow pathway. The purposes of this study were to define the dimension of Koch's triangle and its related anatomical distance and correlate these parameters with the successful ablation sites in patients with AV nodal reentrant tachycardia. Methods and Results: We studied 218 patients with AV nodal reentrant tachycardia. The distance between the presumed proximal His-bundle area and the base of the coronary sinus orifice (D_His-Os) measured in the right anterior oblique view was used to define the dimension of Koch's triangle. The distance of the proximal His-bundle recording site from the successful ablation site (D_His-Ab) and the distance as a fraction of the entire length of Koch's triangle (D_His-Ab/D_His-Os) were determined. The mean D_His-Os, and D_His-Ab were 25.9 ± 7.9 and 13.4 ± 3.8 mm, respectively. D_His-os negatively correlated with patient age (r = -0.41, P < 0.0001) and body mass index (r = -0.18, P = 0.004). Among the patients with successful ablation sites in the medial area, D_His-Os was longer (27.2 ± 6.6 vs 24.6 ± 8.4 mm, P < 0.005), D_His–Ab was similar (12.9 ± 3.1 vs 13.9 ± 4.0, P > 0.05) and D_His-Ab/D_His-Os was smaller (0.48 ± 0.04 vs 0.74 ± 0.11, P < 0.05). Furthermore, the patients with successful ablation sites in the medial location needed more radiofrequency pulse numbers than those in the posterior location (6 ± 4 vs 4 ± 3, P < 0.05). Conclusion: The site of successful slow pathway ablation was consistently about 13 mm from the site recording the proximal His-bundle deflection in patients with AV nodal reentrant tachycardia despite marked variability in the dimensions of Koch's triangle: therefore, patients with large triangles required ablation in the medial region rather than the posterior region. Care should be taken when delivering radiofrequency energy to the posteroseptal area in patients with shorter D_His-Os to avoid injury to AV node.     

Effects of Partial and Complete Ablation of the Slow Pathway on Fast Pathway Properties in Patients with Atrioventricular Nodal Reentrant Tachycardia

Fast Pathway Properties. Introduction: The purpose of this study was to prospectively compare the effects of complete and partial ablation of slow pathway function on the fast pathway effective refractory period (ERP).
Methods and Results: The subjects were 20 patients (mean age 43 ± 13 years) with atrioventricular nodal reentrant tachycardia (AVNRT), no structural heart disease, and easily inducible AVNRT. Autonomic blockade was achieved with propranolol (0.2 mg/kg) and atropine (0.04 mg/kg). After elimination of AVNRT and during autonomic blockade, the presence of residual slow pathway function was determined by the presence of a single AV nodal echo and/or dual AV nodal physiology. After autonomic blockade and before ablation, the mean fast pathway ERP was 319 ± 44 msec and the mean slow pathway ERP was 251 ± 31 msec. After slow pathway ablation and during autonomic blockade, 7 patients had residual slow pathway function and 13 did not. Complete loss of slow pathway function was associated with a shortening of the fast pathway ERP from 334 ± 35 msec to 300 ± 62 msec (P < 0.01), while the fast pathway ERP did not change significantly in patients with residual slow pathway function (291 ± 29 msec vs 303 ± 38 msec, respectively; P = 0.08). A shortening of 30 msec or more in the fast pathway ERP was observed in 11 of 13 patients who did not have residual slow pathway function, compared to 0 of 7 patients with residual slow pathway function (P < 0.001).
Conclusion: Shortening of the fast pathway ERP after successful ablation of AVNRT is dependent upon complete loss of slow pathway function. This observation is consistent with electrotonic inhibition of the fast pathway by the slow pathway.