Delayed Circumflex Artery Stenosis Following Endocardial Left Posterolateral Accessory Pathway Ablation

1008-14 Radiofrequency Catheter Ablation of Left-sided Accessory Pathways: Selection of Coronary Sinus as the Primary Approach

Catheter ablation of coronary sinus accessory pathways in the young

When to sear, when to burn, and when to chop: The art of substrate modification

Radiofrequency (RF) catheter ablation is the treatment of choice in patients with accessory pathways (APs) and Wolff-Parkinson-White syndrome. Endocardial catheter ablation has limitations, including the inability to map and ablate intramural or subepicardial APs. Some of these difficulties can be overcome using an epicardial approach performed through the epicardial venous system or by percutaneous catheterisation of the pericardial space. When a suspected left inferior or infero-paraseptal AP is refractory to ablation or no early activation is found at the endocardium, a transvenous approach via the coronary sinus is warranted because such epicardial pathways can be in close proximity to the coronary venous system. Associated congenital abnormalities, such as right atrial appendage, right ventricle diverticulum, coronary sinus diverticulum and absence of coronary sinus ostium, may also hamper a successful outcome. Percutaneous epicardial subxiphoid approach should be considered when endocardial or transvenous mapping and ablation fails. Epicardial mapping may be successful. It can guide and enhance the effectiveness of endocardial ablation. The finding of no epicardial early activation leads to a more persistent new endocardial attempt. When both endocardial and epicardial ablation are unsuccessful, open-chest surgery is the only option to eliminate the AP.

Radiofrequency (RF) catheter ablation is the treatment of choice in patients with accessory pathways (APs) and Wolff–Parkinson–White syndrome. Endocardial catheter ablation has limitations, including the inability to map and ablate intramural or subepicardial APs. Some of these difficulties can be overcome using an epicardial approach performed through the epicardial venous system or by percutaneous catheterisation of the pericardial space. When a suspected left inferior or infero-paraseptal AP is refractory to ablation or no early activation is found at the endocardium, a transvenous approach via the coronary sinus is warranted because such epicardial pathways can be in close proximity to the coronary venous system. Associated congenital abnormalities, such as right atrial appendage, right ventricle diverticulum, coronary sinus diverticulum and absence of coronary sinus ostium, may also hamper a successful outcome. Percutaneous epicardial subxiphoid approach should be considered when endocardial or transvenous mapping and ablation fails. Epicardial mapping may be successful. It can guide and enhance the effectiveness of endocardial ablation. The finding of no epicardial early activation leads to a more persistent new endocardial attempt. When both endocardial and epicardial ablation are unsuccessful, open-chest surgery is the only option to eliminate the AP.

High rates of success using radiofrequency ablation energy have rapidly transformed catheter ablation from an investigational procedure to the nonpharmacological therapy of choice for symptomatic Wolff-Parkinson-White syndrome. Prior studies of radiofrequency accessory pathway ablation were based on a ventricular approach. Risks associated with prolonged arterial catheter manipulation, retrograde left ventricular catheterization, and production of ventricular lesions required for successful ventricular insertion ablation can be avoided using atrial insertion ablation procedures. The purpose of the present study was to define the safety and efficacy of accessory pathway ablation using radiofrequency energy delivered solely to accessory atrioventricular pathway atrial insertion sites. One hundred fourteen patients with accessory pathway-mediated tachycardia underwent attempted radiofrequency current ablation at the accessory pathway atrial insertion site. All catheters were introduced transvenously. Left-sided accessory pathways were approached using transseptal left atrial catheterization techniques. Retrograde localization of the atrial insertion site during reentrant tachycardia was characterized by 40 +/- 15-msec local ventriculoatrial and 79 +/- 17-msec surface QRS to local atrial electrogram intervals. Presumed accessory pathway potentials were present in only 30% of ablation site electrograms. Successful ablation required 6.2 +/- 5.3 radiofrequency energy applications. Cumulative energy dose required for success was 2,341 +/- 2,233 J. There were no complications associated with transseptal catheterization. Energy delivery to accessory pathway atrial insertion sites was associated with non-life-threatening complications in two patients. Recurrent conduction requiring repeat ablation occurred in 10 of 115 (9%) successfully ablated accessory pathways, all within 1 month of the ablation procedure. After 21.2 +/- 4.6 months of follow-up, 108 of 114 (95%) patients are asymptomatic and without evidence of accessory pathway conduction. The atrial insertion approach to accessory pathway ablation is safe and highly effective. This approach compares favorably with the retrograde ventricular insertion ablation technique. Atrial insertion ablation eliminates the need to produce ventricular lesions and avoids the risks of prolonged arterial catheter manipulation and retrograde left ventricular catheterization.

Sinus arrest during radiofrequency ablation from the inferoseptal process of the left ventricle: Proposed mechanisms of an uncommon finding

By definition, accessory atrioventricular pathways are aberrant muscle bundles that connect the atrium to a ventricle outside of the regular atrioventricular conduction system. Clinically, they may manifest as substrates for ventricular preexcitation. The first accessory pathway in a patient who suffered from Wolff-Parkinson-White syndrome was described in 1943 by Wood, Wolferth, and Geckler.1 Shortly after, Ohnell created a reconstruction of an accessory pathway that very elegantly showed the close proximity of the pathway to the fibrous attachment of the mitral valve and its relationship with the sulcus coronarius (Figure, A).2 Subsequent histological studies have demonstrated unequivocally that these pathways are the anatomic substrates for the classical Wolff-Parkinson-White variety of preexcitation. Figure. A, Ohnell’s depiction of an accessory bundle in the left atrioventricular groove.2 Reprinted with permission from Blackwell Publishing. B, Histological section stained with Masson’s trichrome (fibrous tissue in green and myocardium in red) to show an accessory left-sided pathway (arrow) skirting the mitral annulus. C, Histological section showing a broad right-sided accessory pathway (arrow) that is formed by a myocardial pouch extending from the right atrial appendage to the ventricle and ultimately traced to a small right ventricular vein. This pathway is some distance from the fibrous annulus of the tricuspid valve. *Valvar annulus. Article p 1508 Accessory atrioventricular pathways are found most often in the parietal atrioventricular junctional areas, including the paraseptal areas. They breach the insulation provided by the fibrofatty tissues of the atrioventricular groove (sulcus tissue) and the hingelines (fibrous annulus) of the valves. They are rarely found in the area of fibrous continuity between the aortic and mitral valves because in this area, there is usually a wide gap between the atrial myocardium and ventricular myocardium to accommodate the aortic outflow tract. On the left parietal side, the accessory pathways tend …

The epicardial location of an arrhythmia could be responsible for unsuccessful endocardial catheter ablation. In 48 patients referred after prior unsuccessful endocardial ablation, we considered percutaneous, subxiphoid instrumentation of the pericardial space for mapping and ablation. Thirty patients had ventricular tachycardia (VT), 6 patients had a right- and 4 had a left-sided accessory pathway (AP), 4 patients had inappropriate sinus tachycardia, and 4 patients had atrial arrhythmias. Of the 30 VTs, 24 (6 with ischemic cardiomyopathy, 3 with idiopathic cardiomyopathy, and 15 with normal hearts) appeared to originate from the epicardium. Seventeen (71%) of these 24 VTs were successfully ablated with epicardial lesions. The other 7 VTs had early epicardial sites that were inaccessible, predominantly because of interference from the left atrial appendage. Six of these were successfully ablated from the left coronary cusp. In 5 of the 10 patients with an AP, the earliest activation was recorded epicardially. Three of these were right atrial appendage-to-right ventricle APs, and epicardial ablation was successful. No significant complications were observed. Failure of endocardial ablation could reflect the presence of an epicardial arrhythmia substrate. Epicardial instrumentation and ablation appeared feasible and safe and provided an alternative strategy for the treatment of patients with a variety of arrhythmias. This was particularly true for VT, including patients without structural heart disease.

Endocardial catheter ablation of accessory pathways is now considered as therapy of first choice in symptomatic patients. Success rates depend on the location of the accessory pathway itself and the operators experience in catheter ablation procedures. In patients with a left-sided pathway the retrograde transaortic catheter approach is used routinely in most centers. Besides occasional injuries of the vessels used for catheter placement and perforation of the cardiac chambers, there have been only a few case reports in the literature reporting rare procedure-specific complications such as catheter entrapment within the mitral valve apparatus and occlusion of the left circumflex coronary artery. We report a case of primary successful endocardial catheter ablation of a left lateral accessory pathway in a patient with normal coronary arteries at that time. Many years later progressive deterioration of systolic left ventricular function was observed. Coronary angiography revealed occlusion of LAD next to a arteriovenous (AV) fistula between the LAD and the anterior right ventricle. Endocardial catheter ablation was the only known cardiac manipulation in this patient raising the possibility that unintended catheter manipulations within the LAD had led to this rare and severe complication.

Epicardial mapping and ablation of accessory pathways through a subxiphoid approach can be an alternative when endocardial or epicardial transvenous mapping has failed. We reviewed acute and long-term follow-up of 21 patients (14 males) referred for percutaneous epicardial accessory pathway ablation. There was a median of 2 previous failed procedures. All patients were highly symptomatic, 8 had atrial fibrillation (3 with cardiac arrest) and 13 had frequent symptomatic episodes of atrioventricular reentrant tachycardia. Six patients (28.5%) had a successful epicardial ablation. Five patients (23.8%) underwent a successful repeated endocardial mapping, and ablation after epicardial mapping yielded no early activation site. Epicardial mapping was helpful in guiding endocardial ablation in 2 patients (9.5%), showing that the earliest activation was simultaneous at the epicardium and endocardium. Four patients (19%) underwent successful open-chest surgery after failing epicardial/endocardial ablation. Two patients (9.5%) remained controlled under antiarrhythmic drugs after unsuccessful endocardial/epicardial ablation. Two patients had a coronary sinus diverticulum and one a right atrium to right ventricle diverticulum. Three patients acquired postablation coronary sinus stenosis. There was no major complication related to pericardial access. Percutaneous epicardial approach is an alternative when conventional endocardial or transvenous epicardial ablation fails in the elimination of the accessory pathway. A new attempt by endocardial approach was successful in a significant number of patients. Open-chest surgery may be required in symptomatic cases refractory to endocardial-epicardial approach.

Experience with percutaneous epicardial ablation of tachyarrhythmia in pediatrics is limited. This case series addresses the feasibility, safety, and complications of the procedure in children. A total of nine patients underwent 10 epicardial ablation procedures from 2002 to 2013 at two academic centers. Activation mapping was performed in all cases, and electroanatomic map was utilized in nine of the 10 procedures. Patients had undergone one to three failed endocardial catheter ablations in addition to medical management, and all had symptoms, a high-risk accessory pathway (AP), aborted cardiac arrest with Wolff-Parkinson-White syndrome (WPW), or ventricular dysfunction. A standard epicardial approach was used for access in all cases, using a 7- or 8- Fr sheath. Epicardial ablation modality was radiofrequency (RF) in seven, cryoablation (CRYO) in one, and CRYO plus RF in one. Median age was 14 (range 8-19) years. drug refractory ectopic atrial tachycardia (one), ventricular tachycardia (VT) (five), high-risk AP (two), and aborted cardiac arrest from WPW - (one). Epicardial ablation was not performed in one case despite access due to an inability to maneuver the catheter around a former pericardial scar. VT foci included the right ventricular outflow tract septum, high posterior left ventricle (LV), LV outflow tract, postero-basal LV, and scar from previous rhabdomyoma surgery. WPW foci were in the area of the posterior septum and coronary sinus in all three cases. Overall procedural success was 70% (7/10), with epicardial ablation success in five and endocardial ablation success after epicardial mapping in two. The VT focus was close to the left anterior descending coronary artery in one of the unsuccessful cases in which both RF and CRYO were used. There was one recurrence after a successful epicardial VT ablation, which was managed with a second successful epicardial procedure. There were no other recurrences at more than 1 year of follow-up. Complications were minimal, with one case of inadvertent pleural access requiring no specific therapy. No pericarditis or effusion was seen in any of the patients who underwent epicardial ablation. Epicardial ablation in pediatric patients can be performed with low complications and acceptable success. It can be considered for a spectrum of tachycardia mechanisms after failed endocardial ablation attempts and suspected epicardial foci. Success and recurrence may be related to foci in proximity to the epicardial coronaries, pericardial scar, or a distant location from the closest epicardial location. Repeat procedures may be necessary.

Due to the limited myocardial lesions produced by radiofrequency current, the ablation of accessory pathways (AP) requires precise localization of such connections. The purpose of this study was to ascertain which characteristic(s) of the local bipolar electrogram, recorded from the ablation and adjacent electrode immediately prior to the application of radiofrequency current, correlated with precision in localization adequate to permit AP ablation. Signal analysis was performed for 326 sets of electrograms preceding the attempted ablation of 107 APs in 100 consecutive patients. For 80 antegrade APs, the following variables were evaluated: (1) the presence or absence of an AP potential; (2) the local atrial-AP interval; (3) the local atrioventricular (AV) interval; and (4) the relationship between the onset of local ventricular depolarization and onset of delta wave of the surface electrocardiogram. For the 27 concealed APs, the following characteristics were evaluated: (1) the presence or absence of an AP potential; and (2) the local VA interval during reciprocating tachycardia or ventricular pacing. Antegrade APs: By statistical analysis, the best correlate of successful ablation of an antegrade AP was a local AV interval less than or equal to 40 msec (positive predictive value = 94%; 95% confidence intervals [CI] = 81%-100%). Local AV intervals less than or equal to 50 msec preceded 88% of successful AP ablations, compared to only 8% of failed radiofrequency current applications. The positive predictive value of the other variables were: presence of an AP potential: 35% (95% CI = 27%-40%); local atrial-AP intervals less than or equal to 40 msec: 54% (95% CI = 43%-66%); and local ventricular depolarization preceding onset of the delta wave 43% (95% CI = 34%-52%). For concealed APs, the positive predictive value of a VA interval less than 60 msec was 71% (95% CI = 48%-88%); the positive predictive value for the presence of an AP potential was 58% (95% CI = 32%-81%). No single electrogram characteristic had a positive predictive value and a sensitivity greater than 90% for AP localization adequate for radiofrequency current ablation. For antegrade APs, the best correlate of adequate localization was a local AV interval less than or equal to 40 msec; as a corollary, radiofrequency current applications at sites where the local AV was greater than 60 msec, were unlikely to be effective. Objective criteria for the localization of concealed APs were less certain. Electrogram analysis, as a guide to AP localization and ablation, requires careful analysis of multiple variables, with analysis of the local AV interval a salient objective factor.

The purpose of this study was to determine the incidence and types of venous branches and anomalies in posteroseptal accessory pathways (APs) and whether these findings are indicative for successful ablation sites. Some posteroseptal APs may be located epicardially, or may be associated with venous anomalies or related to the middle cardiac vein. These APs account for many of the failures encountered during endocardial ablation. Direct coronary sinus (CS) angiography was performed in 43 consecutive patients with left posteroseptal APs (n = 23) and in 20 patients with AV nodal reentrant tachycardia prior to catheter ablation. In 14 (61%) of 23 APs, a venous branch or an anomaly of the CS was found in the posteroseptal region (6 with middle cardiac vein, 2 with other ventricular venous branches, and 6 had a diverticulum). Eleven (48%) of 23 APs were successfully abolished from within that demonstrated venous system, with a median of four radiofrequency impulses. In the remaining 12 (52%) patients, ablation was attempted from the endocardial site of the mitral annulus. Repeat angiography after energy delivery revealed no major complications in any patient. One (5%) patient with AV nodal reentrant tachycardia had evidence of a CS anomaly (P < 0.01). Various types of venous branches and anomalies are associated with the majority of patients with left posteroseptal APs. The APs are directly related to these complex findings, and AP conduction can easily be eliminated from within the venous branches. CS angiography is suggested prior to catheter ablation of left posteroseptal APs to facilitate the ablation procedure.

Ultra‐high‐resolution mapping is useful in the ablation of accessory pathways. However, in patients with accessory pathways in the coronary sinus (CS) diverticulum, treatment with endocardial ablation may be challenging. Patients suspected of having subepicardial accessory pathways may require the examination of the venous anomaly using CS angiography.