Left Free Wall Accessory Pathway Research Articles

Cannon A wave validation as a diagnostic tool in paroxysmal supraventricular tachycardias.

The presence of cannon A waves, the so called "frog sign", has traditionally been considered diagnostic of atrioventricular nodal re-entrant tachycardia (AVNRT). Nevertheless, it has never been systematically evaluated. The aim of this study is to assess the independent diagnostic utility of cannon A waves in the differential diagnosis of supraventricular tachycardias (SVTs). We prospectively included 100 patients who underwent an electrophysiology (EP) study for SVT. The right jugular venous pulse was recorded during the study. In 61 patients, invasive central venous pressure (CVP) was registered as well. CVP increase is thought to be related with the timing between atria and ventricle depolarization; two groups were prespecified, the short VA interval tachycardias (including typical AVNRT and atrioventricular reciprocating tachycardia (AVRT) mediated by a septal accessory pathway) and the long VA interval tachycardias (including atypical AVNRT and AVRT mediated by a left free wall accessory pathway). The relationship between cannon A waves and AVNRT did not reach the statistical significance (OR: 3.01; p=.058); On the other hand, it was clearly associated with the final diagnosis of a short VA interval tachycardia (OR: 10.21; p<.001). CVP increase showed an inversely proportional relationship with the VA interval during tachycardia (b=-.020; p<.001). CVP increase was larger in cases of AVNRT (4.0mmHg vs. 1.2mmHg; p<.001) and short VA interval tachycardias (3.9mmHg vs. 1.2mmHg; p<.001). The presence of cannon A waves is associated with the final diagnosis of short VA interval tachycardias.

The Value of Programmed Ventricular Extrastimuli From the Right Ventricular Basal Septum During Supraventricular Tachycardia

BackgroundThe difference between the right ventricular (RV) apical stimulus–atrial electrogram (SA) interval during resetting of supraventricular tachycardia (SVT) versus the ventriculoatrial (VA) interval during SVT (ΔSA-VAapex) is an established technique for discerning SVT mechanisms but is limited by a significant diagnostic overlap. ObjectivesThis study hypothesized that the difference between the RV SA interval during resetting of SVTs versus the VA interval during SVTs (ΔSA-VA) would yield a more robust differentiation of atrioventricular nodal re-entrant tachycardia (AVNRT) from atrioventricular reciprocating tachycardia (AVRT) when using the RV basal septal stimulation (ΔSA-VAbase) as compared to the RV apical stimulation (ΔSA-VAapex). Moreover, it was predicted that the ΔSA-VAbase might distinguish septal from free wall accessory pathways (APs) effectively. MethodsIn this prospective study, 105 patients with AVNRTs (age 48 ± 20 years, 44% male) and 130 with AVRTs (age 26 ± 18 years, 54% male) underwent programmed ventricular extrastimuli delivered from both the RV basal septum and RV apex. The ΔSA-VA values were compared between the 2 sites. ResultsThe ΔSA-VAbase was shorter than the ΔSA-VAapex during AVRT (44 ± 30 ms vs 58 ± 29 ms; P < 0.001), and the opposite occurred during AVNRT (133 ± 31 ms vs 125 ± 25 ms; P = 0.03). A ΔSA-VAbase of ≧85 milliseconds had a sensitivity of 97% and specificity of 96% for identifying AVNRT. Furthermore, a ΔSA-VAbase of 45-85 milliseconds identified AVRT with left free wall APs (sensitivity 86%, specificity 95%), 20-45 milliseconds for posterior septal APs (sensitivity 72%, specificity 96%), and <20 milliseconds for right free wall or anterior/mid septal APs (sensitivity 86%, specificity 98%). ConclusionsThe ΔSA-VAbase during programmed ventricular extrastimuli produced a robust differentiation between AVNRT and AVRT regardless of the AP location with ≧85 milliseconds as an excellent cutoff point. This straightforward technique further allowed localizing 4 general AP sites.

Simple electrocardiography algorithm for localizing accessory pathway in patients with Wolff–Parkinson–White syndrome

Background Existing algorithms to predict the location of an accessory pathway (AP) in Wolff–Parkinson–White Syndrome (WPW) have good sensitivity and specificity but complex with various accuracy and inter-observer agreement rates. A simple algorithm with high accuracy and inter-observer agreement rates is needed. Methods This was a cross-sectional and retrospective diagnostic study. The data were collected by total population sampling from January 2015 to January 2017. Forty-seven patients were included in the study. Data collected were pre-ablation 12-lead ECGs and ablation reports. These ECGs were evaluated by two independent observers using the simplified algorithm and compared with ablation results. Results The algorithm had a sensitivity of 45% on the left free wall, 80% on septal, 92% on the right free wall, and the specificity of 96% on the left free wall, 69% on the septal, 85% on the right free wall for AP prediction. The positive predictive value was 90% on the left free wall, 55% on the septal, and 67% on the right free wall APs. The negative predictive value was 70% on the left free wall, 88% on the septal, and 97% on right free wall AP. The positive likelihood ratio was 11.23 on the left free wall, 2.23 on septal and 6.57 on right free wall APs, and the negative likelihood ratio was 0.57 on left free wall APs, 0.28 on septal, and 0.09 on the right free wall APs. Algorithm accuracy varied from 73–87%. Inter-observer agreement calculation was kappa 0.93 for left free wall AP, 0.78 for septal AP, and 0.74 for right free wall AP. Conclusion This simple algorithm has a remarkable accuracy and inter-observer agreement; therefore, it may prove to be helpful even to non-electrophysiologists and has the potential to be integrated into clinical practice

Coumel's sign reversed: What is the mechanism?

A patient presented with documented narrow QRS tachycardia. During electrophysiological study, he has orthodromic reciprocating tachycardia with atrial activation consistent with left free wall accessory pathway. With induction of tachycardia, beats with LBBB morphology have shorter cycle length than those with narrow QRS. What is the mechanism?

Left atrial \u0131ntramural hematoma after radiofrequency catheter ablation of left lateral accessory pathway

We report a case of left atrial hematoma after ablation of left lateral concealed accessory pathway. A 46-year-old male patient experienced chest pain after radiofrequency ablation. Transthoracic echocardiography and computed tomography revealed the intramural mass consistent with hematoma in the left atrium. He was hemodynamically stable, and conservative approach was decided. Atrioventricular groove is a vulnerable part of left atrium, and ablation of left free wall accessory pathway may require targeting both atrial and ventricular surfaces of the mitral annulus. Avoidance of forceful catheter manipulation during the electrophysiological procedure is important for prevention of this complication. Optimal periprocedural anticoagulation might reduce the risk of procedure-related thromboembolic complications, but electrophysiologists should always pay attention to an intramural hematoma that may occur after radiofrequency catheter ablation.

Antidepressants Relieved Consecutive Chest Pain after Radiofrequency Ablation

Preexcitation symptom presents morbidity of 0.1% to 0.3% in the general population, which could lead to deadly events while accompanying arrhythmia. The classical type is Wolff-Parkinson-White (WPW) syndrome characterized as a shorter PR period, longer QRS duration, and δ wave. Radiofrequency catheter ablation (RCA) takes a vital role in treating WPW and has a high success rate. While some patients complain of consecutive chest pain after RCA, which influence their daily life severely. A 45-year-old man went to a hospital for examination because of uncomfortable palpitation. The electrocardiogram (ECG) presenting WPW syndrome (left free wall accessory pathway), then he was admitted to the hospital and scheduled for RCA. The RCA was very successful and the ECG became normal. However, after ablation, he reported consecutive chest pain, accompanied by insomnia and hypertension. No abnormal elevations of cardiac-Troponin I, myoglobin, cytokeratin, creatine kinase MB were found, and the left ventricular ejection fraction was 60%. His mental status was measured by Patient-Health Questionnaire-9, 7-item Generalized Anxiety Disorder Scale-7, Athens Insomnia Scale, indicating depressive status and anxiety status. The predominant managements involved flupentixol-melitracen and duloxetine. His chest pain, depressive, and anxiety symptoms were gradually relieved after 3-month treatment, and the drugs were slowly tapered in the 1½ years' follow-up period. Ultimately, he recovered and worked as before. This case highlights the importance of evaluating psychological status in patients with unexplained chest pain resulting from RCA and adopting antidepressants in those patients that coexist with definite depression or anxiety.

Development and evaluation of 12-lead electrocardiogram in the left free wall of accessory pathway localization in patients with typical Wolff-Parkinson-White syndrome

Objectives: This study was designed to characterize 12-lead electrocardiogram (ECG) for localization of the left free wall lateral accessory pathway (AP) in patients with typical Wolff-Parkinson-White (WPW) syndrome, to develop a new algorithm ECG for localizing APs, and to test the accuracy of the algorithm prospectively.&#x0D; Method: We studied 129 patients; 84 patients had typical WPW syndrome with single anterograde AP identified by successful radiofrequency catheter ablation (RFCA), and were enrolled to build a new ECG algorithm for localizing left free wall APs. Then, the algorithm was tested prospectively in 45 patients and compared with the location of APs successfully ablated by RFCA.&#x0D; Results: We found that the 12-lead ECG parameters in typical WPW syndrome, such as delta wave polarity in V1, R/S ratio in V1, transition of the QRS complex, and delta wave polarity in inferior, lead to diagnosis and localization of APs, with highest accuracy predicted from 74.5%-100%, and for development of a new ECG algorithm. From the 45 patients who were prospectively evaluated by the newly derived algorithm for the left free wall pathways, the sensitivity and specificity was high (from 75-100%).&#x0D; Conclusion: The 12-lead ECG parameters in typical WPW syndrome are closely related to left free wall AP localization and can be used to develop a new ECG algorithm by the parameters above. Moreover, the new ECG algorithm can predict the location of APs with high accuracy.&#x0D;

A Simple Method to Differentiate Atrioventricular Node Reentrant Tachycardia from Orthodromic Reciprocating Tachycardia.

Discrimination between atrioventricular node reentry tachycardia (AVNRT) and orthodromic reciprocating tachycardia (ORT) during an electrophysiological study is sometimes challenging. This study aimed to investigate if the difference in the local VA (ventricle-atrium) interval during ventricular entrainment pacing and during tachycardia (DVA, defined as the shortest local VA interval of coronary sinus [CS] during entrainment minus the shortest local VA interval of CS during tachycardia) was different in patients with AVNRT and patients with ORT.Diagnoses of AVNRT or ORT through a concealed accessory pathway (AP) were made according to conventional electrophysiological criteria and ablation results. Entrainment by right ventricular (RV) pacing was performed in each patient before ablation and patients with successful entrainment were included in the study. The DVA was compared between patients with AVNRT and patients with ORT. The DVA in patients with AVNRT was significantly longer than that in patients with ORT (120 ± 20 versus 5.7 ± 9; P < 0.001). In each patient with AVNRT of slow-fast type, fast-slow type, and slow-slow type, the DVA was more than 48 ms. In each patient with ORT using a left free wall accessory pathway (AP), right free wall AP, and septal AP, the DVA was less than 20 ms.DVA was found to be a rapid, useful test in distinguishing patients with AVNRT from those with ORT.

左室自由壁副伝導路を介するpermanent form of junctional reciprocating tachycardia (PJRT) の乳児例

左室自由壁副伝導路を介するpermanent form of junctional reciprocating tachycardia (PJRT) の乳児例

A Reminder of Treatments Past

The Wolff-Parkinson-White (WPW) syndrome was initially described in 1930 as a clinical syndrome of paroxysmal tachycardias in healthy young people that demonstrated “bundle-branch block and short P-R interval”. These tachycardias were eventually determined to be macro-reentrant arrhythmias utilizing accessory pathways. Surgical approaches for transecting these accessory pathways were being developed as early as the 1960s. Since 1984, catheter ablation has developed into a safe and highly effective therapy option, and the treatment of choice for WPW syndrome today. We present a unique case of a patient with previous surgically treated WPW syndrome that serves as a reminder of treatments past and caution for current therapies. A 54-year-old man with a remote history of WPW syndrome, treated in 1989 with surgical cryoablation of a left ventricular free wall accessory pathway, now presented with an hour of sustained palpitations after a triathlon practice session. He was found to have ventricular tachycardia at a rate of 180 bpm on EKG requiring external cardioversion. The troponin I level peaked at 2.59 ng/mL. Left heart catheterization revealed a peculiar truncated 100% occlusion of the proximal circumflex artery with extensive bridging collaterals to the mid circumflex artery, and also confirmed an infero-basal aneurysm. The cause of the ventricular tachycardia (VT) was deemed non-ischemic and he was referred for electrophysiology study. 3D electroanatomic mapping of the left ventricular (LV) endocardial surface was performed, revealing a discrete posterior wall scar. Reentrant VT was repeatedly induced utilizing a zone of slow conduction along the border zone of the scar. Radiofrequency ablation of Purkinje potentials on the LV septum, running alongside the scar border zone, eliminated the VT. The entire endocardial surface of the postero-basal scar was electrically silenced to prevent further VT events. Typically, during the surgical approach of WPW, a wide endocardial (rarely an epicardial) incision was made along the atrial surface of the mitral valve annulus, dissecting deeply and caudally until ventricular myocardium was exposed. Despite the close proximity of the circumflex artery to the epicardial incision line during these surgeries, there are only rare reports of coronary artery complications, generally considered to be either catheter-induced dissections or embolic events. The development of a network of extensive bridging collaterals in our patient supports progressive stenosis of the left circumflex artery from cryoablation thermic injury, leading to scar formation and VT years later. In conclusion, this case reminds us that current ablative therapies are still relatively new, and long-term follow-ups for delayed complications remain a necessity. J Med Cases. 2016;7(6):216-219 doi: http://dx.doi.org/10.14740/jmc2488w

A REMINDER OF TREATMENTS PAST

The Wolff-Parkinson-White (WPW) syndrome was initially described in 1930 as a clinical syndrome of paroxysmal tachycardias in healthy young people that demonstrated “bundle-branch block and short P-R interval”. These tachycardias were eventually determined to be macro-reentrant arrhythmias utilizing accessory pathways. Surgical approaches for transecting these accessory pathways were being developed as early as the 1960s. Since 1984, catheter ablation has developed into a safe and highly effective therapy option, and the treatment of choice for WPW syndrome today. We present a unique case of a patient with previous surgically treated WPW syndrome that serves as a reminder of treatments past and caution for current therapies. A 54-year-old man with a remote history of WPW syndrome, treated in 1989 with surgical cryoablation of a left ventricular free wall accessory pathway, now presented with an hour of sustained palpitations after a triathlon practice session. He was found to have ventricular tachycardia at a rate of 180 bpm on EKG requiring external cardioversion. The troponin I level peaked at 2.59 ng/mL. Left heart catheterization revealed a peculiar truncated 100% occlusion of the proximal circumflex artery with extensive bridging collaterals to the mid circumflex artery, and also confirmed an infero-basal aneurysm. The cause of the ventricular tachycardia (VT) was deemed non-ischemic and he was referred for electrophysiology study. 3D electroanatomic mapping of the left ventricular (LV) endocardial surface was performed, revealing a discrete posterior wall scar. Reentrant VT was repeatedly induced utilizing a zone of slow conduction along the border zone of the scar. Radiofrequency ablation of Purkinje potentials on the LV septum, running alongside the scar border zone, eliminated the VT. The entire endocardial surface of the postero-basal scar was electrically silenced to prevent further VT events. Typically, during the surgical approach of WPW, a wide endocardial (rarely an epicardial) incision was made along the atrial surface of the mitral valve annulus, dissecting deeply and caudally until ventricular myocardium was exposed. Despite the close proximity of the circumflex artery to the epicardial incision line during these surgeries, there are only rare reports of coronary artery complications, generally considered to be either catheter-induced dissections or embolic events. The development of a network of extensive bridging collaterals in our patient supports progressive stenosis of the left circumflex artery from cryoablation thermic injury, leading to scar formation and VT years later. In conclusion, this case reminds us that current ablative therapies are still relatively new, and long-term follow-ups for delayed complications remain a necessity. J Med Cases. 2016;7(6):216-219 doi: http://dx.doi.org/10.14740/jmc2488w

Percutaneous Retrieval of an Entrapped Ablation Catheter during a Retrograde Approach for a Left Free Wall Accessory Pathway

A 25-year-old man suffered from repeated attacks of orthodromic atrioventricular reciprocating tachycardia utilizing a left lateral accessory pathway (AP) for retrograde conduction. The catheter was approached through the aorta to map the AP and was entrapped in the mitral valve apparatus, and it had a broken internal wire. A snareassisted technique was successfully utilized to retrieve the catheter.

Left lateral free wall pathway ablation complicated by plaque rupture and acute occlusion of the left anterior descending coronary artery

Radiofrequency (RF) ablation of accessory bypass tracts associated with the Wolff -Parkinson-White (WPW) syndrome has become the treatment of choice for many arrhythmias. Complications are unusual and acute coronary artery occlusion is very rare. We here present a 38-year-old male patient with an acute occlusion of proximal left anterior descending (LAD) coronary artery after RF ablation of a left free wall accessory pathway. An interesting feature is the site of the coronary artery occlusion which is remote from the RF application site. The occlusion was successfully treated with the placement of an intracoronary stent.

A simple algorithm for localizing accessory pathways in patients with Wolff-Parkinson-White syndrome using only the R/S ratio

BackgroundSeveral algorithms for localizing accessory pathways (APs) are based on the delta wave morphology, R/S ratio, and QRS polarity. However, they are somewhat complicated, and an accurate determination of the delta wave morphology is occasionally difficult. The aims of this study were to develop a simple algorithm for localizing APs using only the R/S ratio, and to test the accuracy of the algorithm prospectively. MethodsWe studied 142 patients with a single anterogradely conducting AP on a 12-lead ECG. R/S ratios were analyzed in leads V1, V2, and aVF (R/S-V1, R/S-V2, and R/S-aVF). AP locations were divided into five regions based on fluoroscopic anatomy. ResultsA new algorithm was developed by correlating R/S-V1, R/S-V2, and R/S-aVF with successful ablation sites in 88 initial consecutive patients. All 55 patients with left free wall APs showed R/S-V1 ≥0.5, and 47 (98%) of 48 patients with left anterior or lateral APs showed R/S-aVF ≥1. In contrast, all seven patients with left posterolateral or posterior APs showed R/S-aVF <1. All nine patients with right-and-left midseptal or posteroseptal APs showed R/S-V1 <0.5 and R/S-V2 ≥0.5. Of 12 patients with right anterior, lateral or anteroseptal APs, 10 (83%) showed R/S-V1 <0.5, R/S-V2 <0.5 and R/S-aVF ≥1. Finally, nine (75%) of 12 patients with right posterolateral or posterior APs showed R/S-V1 <0.5, R/S-V2 <0.5, and R/S-aVF <1. Then this algorithm was tested prospectively in 54 patients. Overall, the sensitivity was 94%, and the specificity was 98%. ConclusionsThis ECG algorithm provides a simple and accurate way to identify the AP localization.

Abstract 19013: Symptomatic Spontaneous Automaticity in a Decrementally Conducting Left Free Wall Accessory Pathway in a Patient With Congenital Heart Block

Introduction: A 20 year-old female with a history of a coil-occluded patent ductus arteriosus and congenital complete atrioventricular (AV) block was admitted for a wide complex tachycardia (WCT) associated with palpitations and dizziness. Her LV function was normal and no additional structural heart disease was noted on a cardiac MRI. Electrophysiology (EP) study was performed. Methods: N/A Results: EP study showed sinus tachycardia with 1:1 antegrade conduction via a left-sided accessory pathway. The accessory pathway demonstrated decremental conduction, adenosine responsiveness, and no retrograde conduction. The earliest ventricular activation was noted in the distal coronary sinus electrode. At slower atrial rates (70-100 bpm), there was isorhythmic dissociation (see figure) between the accessory pathway (QRS identical to maximal pre-excitation) and the sinus node strongly suggesting spontaneous accessory pathway automaticity. The accessory pathway was successfully ablated by targeting an accessory pathway potential located at the anterior aspect of the mitral valve. Post-ablation, there was complete AV block with a narrow junctional escape rhythm at a rate of 64 beats per minute. The patient underwent placement of a dual chamber pacemaker. Conclusion: This is, to our knowledge, the first reported case of a left-sided accessory pathway with both spontaneous automaticity and Mahaim-like properties.

Muscular architecture of the mitral isthmus: anatomical determinants for catheter ablation

This editorial refers to ‘The anatomical characteristics of three different endocardial lines in the left atrium: evaluation by computed tomography prior to mitral isthmus block attempt’ by Y. Cho et al ., on page 1104 Early electrophysiological studies demonstrated the presence of an isthmus of conductive tissue in the low lateral left atrium (LA) during ablation of left free-wall accessory pathways.1 These studies introduced the LA ‘isthmus’ concept—a site of intra-atrial conduction block that shows the latest atrial activation during sinus rhythm. Although this posteroinferior area of the lateral LA wall between the orifice of the left inferior pulmonary vein (PV) and the mitral annulus cannot be considered an anatomic entity, it is now termed by electrophysiologists as the LA isthmus, or mitral isthmus. Linear ablation connecting the inferior margin of the ostium of the left inferior PV and the mitral annulus, particularly when complete linear block is achieved, appears to increase the success rate of catheter ablation in patients with atrial fibrillation (AF) and prevent macro-reentry around the mitral annulus or the left PVs.2,3 However, the creation of mitral isthmus lesions by catheter ablation is technically challenging and may be associated with significant complications. Factors that make obtaining a complete, transmural, and permanent ablation line across the mitral isthmus difficult may be electrical as well as anatomical because of the variable and complex endocardial geometry of the LA posterolateral region. Other factors include the unpredictable content of atrial myocardium and the cooling effect of the circumflex artery at different locations of this atrial territory. A better understanding of the anatomo-functional substrate is essential for developing a proper LA isthmus ablation strategy that can contribute to successful outcome. In a valuable anatomic study in 20 hearts, Anton Becker4 showed marked variability in the dimensions of the …

Radiofrequency Catheter Ablation of Left Free Wall Accessory Pathways: Comparison Between Retrograde and Transeptal Approach

Background : This study was conducted to compare the conventional retrograde arterial approach (RAA) with the transeptal approach (TSA) for radiofrequency catheter ablation (RFA) of left accessory pathways (AP). Materials and Methods: Sixty consecutive patients (44 male; mean age of 35.60 ± 11.63 years) with 60 left APs (39 overt and 21 concealed) underwent catheter ablation using the TS method (30 patients) and the RA method (30 patients) in an alternate fashion. The analysis was performed according to the intention-to-treat principle. Results : The transeptal puncture was successfully performed in 29 patients (96%). This access allowed primary success in the ablation in all the patients without any complication. When we compared this approach with the RAA there was no difference as regards the primary success (p = 0.103), fluoroscopy time (p = 0.565) and total time (p = 0.1917). Three patient in the RAA group presented a vascular complication. The TSA allowed shorter ablation times (p=0.006) and smaller number of radiofrequency applications (p = 0.042) as compared to the conventional RAA. The patients who had unsuccessful ablation in the first session in each approach underwent with the opposite technique (cross-over), with a final ablation success rate of 100%. Conclusion : The TS and RA approaches showed similar efficacy and safety for the ablation of left accessory pathways. The TSA allowed shorter ablation times and smaller number of radiofrequency applications. When the techniques were used in a complementary fashion, they increased the final efficacy of the ablation DOI: http://dx.doi.org/10.3329/cardio.v4i2.10458 Cardiovasc. j. 2012; 4(2): 139-147

Left ventricular dyssynchrony in pre-excitation syndrome: effect of accessory pathway location and reversibility after ablation therapy

We sought to evaluate the effects and reversibility of different locations of accessory pathways (AP) on left ventricular dyssynchrony (LVdys). The acute and chronic effects of AP were evaluated in a canine model (n = 11) and in patients with pre-excitation syndrome (n = 25). Pre-excitation was simulated in the canine model by applying VDD-type epicardial ventricular pacing near the atrioventricular (AV) groove with 50-ms AV interval after median thoracotomy, at five different sites in each animal. For the simulation of pre-excitation through the septal accessory pathway, right basal septal pacing was performed using a transvenous lead. Left ventricular dyssynchrony was measured by a two-dimensional speckle-tracking technique: before and during pacing in the canine model, and before and within 24 h after the ablation in patients with Wolff-Parkinson-White (WPW) syndrome. In the canine model, the most prominent intraventricular LVdys was observed in left lateral pre-excitation (P < 0.001). In patients with pre-excitation syndrome, LVdys was greatest in patients with left free wall accessory pathways before the ablation (P = 0.013). After catheter ablation, such a difference diminished (P = 0.619). The degree of LVdys was different according to the site of AP in both the acute model and chronic patients, and the most significant LVdys associated with pre-excitation was observed in left lateral AP. Left ventricular dyssynchrony was reversible in patients with WPW syndrome. Left ventricular dyssynchrony observed in patients with pre-excitation syndrome might be a different entity from that observed in patients with heart failure.

Pseudodisappearance of atrial electrogram during accessory pathway ablation

A concealed left free wall accessory pathway in a patient with palpitations showed only intermittent conduction. Isoprenaline infusion and left ventricular pacing from a …

Abstract 9410: A Simple and Accurate Algorithm for Localizing Accessory Pathways in Patients with Wolff-Parkinson-White Syndrome

Introduction: Delta wave morphology reflects the ventricular attachment site of accessory pathway (AP). Electrocardiographic R/S ratio and QRS polarity also depend on the AP location. Many algorithms for localizing APs are based on the delta wave morphology, R/S ratio, and QRS polarity. However, they are slightly complicated and it is sometimes difficult to determine the delta wave morphology accurately. In this study, we propose a new and simple algorithm for accurate localization of APs using only the R/S ratio. Methods: This study consisted of 101 patients with a single anterogradely conducting AP on a 12-lead ECG. R/S ratios in leads V1, V2 and aVF were analyzed. A new algorithm was developed by correlating the 12-lead ECG findings with successful ablation sites in the 40 initial consecutive patients. This algorithm was subsequently tested in the 61 residual consecutive patients. AP locations were divided into 5 regions based on fluoroscopical anatomy. Results: The new algorithm and the validation results were shown (figure). Among 61 patients, all 37 patients with left free wall APs showed the R/S ratio in lead V1 ≥ 0.5 (sensitivity 100%, specificity 100%). Left anterior and lateral APs were associated with the R/S ratio in lead aVF ≥ 1 (sensitivity 97%, specificity 100%). If the R/S ratio in lead V1 was &lt; 0.5 and the R/S ratio in lead V2 was ≥ 0.5, the AP location was midseptal or posteroseptal (sensitivity 100%, specificity 94%). If the R/S ratio in both leads V1 and V2 was &lt; 0.5, it was right free wall or right anteroseptal (sensitivity 89%, specificity 100%). Right anterior, lateral, and anteroseptal APs were associated with the R/S ratio in lead aVF ≥ 1 (sensitivity 98%, specificity 93%). Overall sensitivity of this method was 93% and specificity was 99%. The positive and negative predictive values were 96% and 98%, respectively. Conclusions: This novel algorithm using only the R/S ratio in leads V1, V2 and aVF provides a simple and accurate way to identify the AP localization.