Coronary Sinus Ostium Research Articles

Anatomical variations of the coronary sinus valve (Thebesian valve): implications for electrocardiological procedures.

The Thebesian valve (TV) can be a significant obstacle to coronary sinus (CS) cannulation. The aim of this study was to evaluate the characteristic features of the CS valve--TV anatomy. In particular, emphasis was placed on identifying specific structures of the TV that could potentially complicate CS cannulation. We examined 273 autopsied human hearts. The height of the TV and the diameter of the CS were measured. The valves were classified according to their shape into five types: remnant, semilunar, fold, cord, and mesh and fenestrated. The mean transverse CS ostium (CSO) diameter was 12.2 ± 3.5 mm. The TV was present in 224 (82.1%) cases. The most common type of TV was semilunar: 32.6%; followed by remnant: 25.5%; fold: 17.4%; cord: 14.3%; and lastly mesh and fenestrated: 10.3%. The mean TV height for remnant-semilunar-fold types was 5.8 ± 3.0 mm. In seven cases, the present TV (2.6%) covered the entire orifice of the CS. Hearts with larger CSO diameter had lower TV height (P < 0.001). We propose a new classification of the TV shapes based on the largest sample to date. We assessed that only in 2.6% of all 273 cases the presence of an obstructive TV can cause unsuccessful cannulation. The height of the TV was inversely correlated to the CSO diameter (r = -0.33; P < 0.001).

Taking the slower pathway.

In this segment of the Teaching Rounds in Electrophysiology, Chen et al1 provide an instructive discussion taking us through one of the most difficult diagnostic differentiations in cardiac electrophysiology—AV nodal re-entry tachycardia (AVNRT) versus junctional tachycardia.2,3 Often the highest educational value in the electrophysiology laboratory when teaching a rule is to recognize and analyze an exception. Chen et al1 induced a slower tachycardia with similar activation sequence as an originally induced AVNRT. After slow pathway ablation and the use of isoproterenol, they had to determine whether further ablation is necessary or could potentially be harmful (slower AVNRT versus junctional tachycardia), importantly they found an exceptional response to premature atrial contractions (PACs) that span the cycle length of the arrhythmia and, with their careful analysis and stepwise logical interpretation of the data, concluded correctly that further slow pathway ablation will eliminate the arrhythmia. See Article p 232 The slow pathway is usually anatomically defined as the myocardium anterior toward the ventricle to the Eustachian ridge and tendon of Todaro, behind the tricuspid annulus septally, and just cranial to the coronary sinus ostium.4 Although exceptions exist for any diagnostic maneuver in the electrophysiology laboratory, maneuvers related to the AV nodal slow pathway can be particularly difficult because there may be anatomic variants and decrement conduction delay within the circuit. Understanding common causes of difficulty with analyzing the results of maneuvers performed and appreciating the diagnostic effect of success and failure with anatomic slow pathway ablation can be important. ### Cycle Length Variation Cycle length stability before initiating a maneuver such as introduction premature atrial beats to perturb the circuit is a paramount for accurate diagnostic interpretation. Occasionally, even if the cycle length varies, the maneuver can be executed, as long as the variation is occurring in a predictable manner. For …

COEXISTENCE of PERMANENT JUNCTIONAL RECIPROCATING TACHYCARDIA with RHEUMATIC VALVULAR DISEASE; A CASE SUCESSFULLY TREATED with RADIOFREQUENCY ABLATION

A seventeen years old female had presented with palpitation. On the electrocardiography (ECG), long RP, narrow QRS tachycardia, inverted P waves in leads D2, D3 and aVF were noticed. On transthoracic echocardiography, rheumatic mitral valvular disease (RMVD) with normal ventricular systolic function was observed. Eccentric mitral regurgitation was also present. Electrophysiology study (EPS) was performed at our institution. According to EPS and surface ECG findings our diagnosis was permanent junctional reciprocating tachycardia (PJRT). Atrial activation appeared earliest and nearly ostium of the coronary sinus. The accessory pathway was detected near the coronary sinus ostium. RF ablation was performed, successfully. Tachycardia was terminated in three seconds. Permanent junctional reciprocating tachycardia can rarely coexist with RMVD. Here, we are reporting a case of PJRT and RMVD coexistence that underwent successful radiofrequency (RF) catheter ablation. This case report confirms that RF catheter ablation should be considered as the treatment of choice in adult patients with PJRT for the following reasons: catheter ablation is highly successful, the complication rate is low, and PJRT may lead to tachycardia induced cardiomyopathy, which is reversible.

Ivabradine and AV conduction

Ivabradine is a heart rate reducing agent that selectively inhibits the If current in the sinus node, without affecting heart contractility, relaxation and peripheral vascular resistance [1]. The clinical efficacy and safety of ivabradine have been confirmed in majormorbidity andmortality studies in patients with heart failure and coronary artery disease. Because the If current is mainly present in the sinus node, the effects of ivabradine can be observed during sinus rhythm. However, recent experimental [2] and clinical observations suggest that ivabradine significantly reduces the ventricular rate during atrial fibrillation [3,4]. In the context of this new and very important data we wish to submit our observation regarding the effects of ivabradine on the AV-node during fixed atrial pacing. A 60-year-old patient with a mechanical mitral valve was admitted with new-onset typical atrial flutter. The patient's only medication was an oral anticoagulant. The following day bidirectional block was created across the right atrial isthmus using radiofrequency ablation. After the termination of flutter, pacing was performed from a lateral tricuspid annulus site and from a coronary sinus ostium site to demonstrate permanent bidirectional block. The patient was given 5 mg oral ivabradine (“off-label”) after the ablation. Ivabradine caused a significant AH time prolongation during fixed cycle length stimulation after 30 min (Fig. 1), whereas the HV time remained unchanged. After the procedure, Holter monitoring showed no bradycardia episodes.

ASSA14-02-04 Electrophysiologic Characteristics and Radiofrequency Catheter Ablation of Atrial Arrhythmia originating from Superior Vena Cava

Objectives To analyse the characteristics of electrocardiogram (ECG) and electrophysiologic and radiofrequency catheter ablation (RFCA), to investigate the diagnosis and strategy of ablation of Atrial Arrhythmia originating from Superior Vena Cava. Methods Choose 14 patients from 2002–2013, all patients acknowledged atrial arrhythmia (atrial fibrillation (AF), atrial tachycardia (AT)) originating from superior vena cava by electrophysiologic examination. 6 of them were male, and the mean age of the 14 patients was 56 ± 7 years, mean case history was 8 ± 7 years. Analyse the ECG P’ waves of atrial premature or atrial tachycardia and electrophysiologic characteristics. When atrial fibrillation, atrial tachycardia happens, identify the origin location and the earliest activation, under the guidance of traditional mapping or three-dimensional (3D) mapping system, combined SVC angiography, if certify SVC is the origin of triggering arrhythmia, ablate the SVC focally, segmentally or circularly. Results Though the 14 cases of atrial arrhythmia originated from SVC, We found that the ECG P’ waves characteristics: 13 patients the P’ waves in lead I were positive, 1 was isoeleetric; 14 patients the P’ waves in lead II were positive, and the amplitude was higher than sinusus P wave; 12 patients the waves in lead III were positive, 2 were positive negative; 13 patients the P’ waves in lead AVF were positive, 1 was isoeleetric; 14 patients the P waves in lead AVR were all negative; the patients of P’ waves in lead V1 positive, negative, positive negative, isoeleetric was 5, 3, 4, 2 respectively. Compared with the sinusus P wave, the P’ waves was significantly higher in lead II, III, AVF. The electrophysiologic characteristics: In SVC and right superior pulmonary veins (RSPV), could record SVC potential, which ahead of coronary sinus ostium (CSO) 50 ± 11 ms sinus rhythm, 93 ± 20 ms atrial premature, p Conclusions Atrial arrhythmia originating from superior vena cava has typical ECG characteristics: P’ waves in lead II, III, AVF was significantly higher than sinusus P wave. The time limit of SVC potential ahead of CSO both sinus rhythm and atrial premature has direction meaning to some extent, which could improve the success rate and decrease recurrence rate. The focal ablation and segmental ablation of SVC could achieve SVC-RA completely electrical isolation. SVC is adjacent to atrionector and right nervus phrenicus anatomically, 3D mapping system is helpful to identify anatomy and target location.

Features of intrinsic ganglionated plexi in both atria after extensive pulmonary isolation and their clinical significance after catheter ablation in patients with atrial fibrillation.

The features of intrinsic ganglionated plexi (GP) in both atria after extensive pulmonary vein isolation (PVI) and their clinical implications have not been clarified in patients with atrial fibrillation (AF). The purpose of this study was to assess the features of GP response after extensive PVI and to evaluate the relationship between GP responses and subsequent AF episodes. The study population consisted of 216 consecutive AF patients (104 persistent AF) who underwent an initial ablation. We searched for the GP sites in both atria after an extensive PVI. GP responses were determined in 186 of 216 patients (85.6%). In the left atrium, GP responses were observed around the right inferior GP in 116 of 216 patients (53.7%) and around the left inferior GP in 57 of 216 (26.4%). In the right atrium, GP responses were observed around the posteroseptal area: inside the CS in 64 of 216 patients (29.6%), at the CS ostium in 150 of 216 (69.4%), and in the lower right atrium in 45 of 216 (20.8%). The presence of a positive GP response was an independent risk factor for AF recurrence (hazard ratio 4.04, confidence interval 1.48-11.0) in patients with paroxysmal, but not persistent, AF. The incidence of recurrent atrial tachyarrhythmias in patients with paroxysmal AF with a positive GP response was 51% vs 8% in those without a GP response (P = .002). The presence of GP responses after extensive PVI was significantly associated with increased AF recurrence after ablation in patients with paroxysmal AF.

Abstract 15996: Left-Variant Form of Slow-Fast AVNRT Requiring Ablation Along the Mitral Annulus

Background: The reentry circuit of the slow-fast AV nodal reentrant tachycardia (AVNRT) has not been precisely delineated. Although conventional right-sided slow pathway ablation at the inferoseptal to midseptal tricuspid annulus (TA) or inside the coronary sinus (CS) is effective in most slow-fast AVNRT cases, rare cases of the left-variant form resistant to the conventional right-sided slow pathway ablation and requiring the left-sided ablation along the mitral annulus (MA) have been reported. Purpose: To evaluate the effects of the left-sided ablation along the MA in patients with the slow-fast AVNRT resistant to the conventional right-sided slow pathway ablation. Methods &amp; Results: In 5 out of 250 cases with the slow-fast AVNRT who underwent the slow pathway ablation, extensive right-sided slow pathway ablation at the mid to inferoseptal TA, CS ostium or inside the CS (&gt;10 applications) failed to eliminate tachycardia inducibility. In those 5 cases, the left-sided ablation along the inferoseptal to inferolateral MA with transseptal approach was performed during the sinus rhythm. In 2 cases, accelerated junctional rhythm was induced during the ablation along the MA and tachycardias were rendered non-inducible (upto one AV nodal echo beat). In other 2 cases, accelerated junctional rhythm was not induced during the ablation along the MA, but tachycardia became non-sustained (2-5 AV nodal echo beats). In the remaining one case, tachycardia still remained inducible even after extensive left-sided ablations. Conclusion: The left-variant forms of the slow-fast AVNRT were observed in 1.6% of all slow-fast AVNRT cases and the slow pathway ablation along the inferoseptal to inferolateral MA was effective for eliminating the tachycardia inducibility. The left-sided deviation of the reentrant circuit might explain the resistance to the right-sided slow pathway ablation and efficacy of the left-sided ablation along the MA in those cases.

Usefulness of entrainment mapping using the activation sequence of the last captured excitation in complex dual-loop atrial tachycardia

BackgroundElectroanatomical mapping is useful for locating the atrial reentrant circuit, but analysis of the dynamic relation of the reentrant circuit is sometimes difficult. This article describes three cases of complex dual-loop reentrant atrial tachycardia analyzed by entrainment mapping using not only the postpacing interval (PPI) but also the activation sequence of the last captured beats. MethodsCase 1 was dual-loop reentry consisting of the tricuspid annulus (TA) and a localized atrial reentry at the coronary sinus (CS) ostium with different exit sites to the right and the left atrium that was cured by catheter ablation at the CS ostium showing fractionated potential. Case 2 was dual-loop reentry around the TA and the superior trans-septal incision line. Case 3 was dual-loop reentry around the TA and longitudinal dissociation along the cavo-tricuspid isthmus. ResultsIn Cases 1 and 2, entrainment with a shorter pacing cycle length demonstrated antidromic penetration to the circuit and changed the activation sequence of the last captured beat depending on the anatomical relation of the reentrant circuit. In Cases 1–3 with dual-loop reentry, the excitation wavefront induced by stimulation entered one circuit after going around the other; thus, the penetration to the other reentry circuit became the second beat after the stimulus (one lap behind). ConclusionsThe PPI is obtained from the pacing site only, but the last captured beat could be obtained from all electrodes. It is advantageous to use the information from all available electrode recordings to determine the dynamic relation between complex dual-loop reentrant circuits.

Characterization of the Nodal Slow Pathway in Patients With Nodal Reentrant Tachycardia: Clinical Implications for Guiding Ablation

Introduction and objectivesNodal slow pathway ablation is the treatment of choice for nodal reentrant tachycardia. No demographic, anatomic, or electrophysiologic variables have been reported to predict an exact location of the slow pathway in the atrioventricular node or its proximity to the fast pathway. The purpose of this study was to analyze these variables. MethodsThe study prospectively included 54 patients (17 men; mean age, 55 [16] years) who had undergone successful slow pathway ablation. The refractory periods of both pathways and their differential conduction time were measured, and calculations were performed to obtain the distance from the His-bundle region (location of the fast pathway) to the coronary sinus ostium (to estimate the anteroposterior length of the triangle of Koch) and to the slow pathway area. ResultsThe differential conduction time (139 [98] ms) did not correlate with the His-coronary sinus distance (19 [6] mm; P=.6) or the His-slow pathway distance (14 [4] mm; P=.4). When the His-coronary sinus distance was larger, the His-slow pathway distance was also larger (r=0.652; P<.01) and the anatomic correlation between the triangle dimensions and the separation between the two pathways was confirmed. In patients older than 70 years, smaller triangle sizes and a shorter distance between both pathways were observed (P<.001). ConclusionsA greater anteroposterior dimension of the triangle of Koch is associated with a slow-pathway location farther from the fast pathway. In elderly patients the two pathways are closer together (higher risk of atrioventricular block).

Caracterización de la vía lenta nodular en pacientes con taquicardia por reentrada nodular: implicaciones clínicas para guiar la ablación

Introduction and objectivesNodal slow pathway ablation is the treatment of choice for nodal reentrant tachycardia. No demographic, anatomic, or electrophysiologic variables have been reported to predict an exact location of the slow pathway in the atrioventricular node or its proximity to the fast pathway. The purpose of this study was to analyze these variables. MethodsThe study prospectively included 54 patients (17 men; mean age, 55 [16] years) who had undergone successful slow pathway ablation. The refractory periods of both pathways and their differential conduction time were measured, and calculations were performed to obtain the distance from the His-bundle region (location of the fast pathway) to the coronary sinus ostium (to estimate the anteroposterior length of the triangle of Koch) and to the slow pathway area. ResultsThe differential conduction time (139 [98] ms) did not correlate with the His-coronary sinus distance (19 [6] mm; P=.6) or the His-slow pathway distance (14 [4] mm; P=.4). When the His-coronary sinus distance was larger, the His-slow pathway distance was also larger (r=0.652; P<.01) and the anatomic correlation between the triangle dimensions and the separation between the two pathways was confirmed. In patients older than 70 years, smaller triangle sizes and a shorter distance between both pathways were observed (P<.001). ConclusionsA greater anteroposterior dimension of the triangle of Koch is associated with a slow-pathway location farther from the fast pathway. In elderly patients the two pathways are closer together (higher risk of atrioventricular block).Full English text available from: www.revespcardiol.org/en

The Thebesian valve and its significance for electrophysiologists.

Invasive cardiac procedures, such as arrhythmia ablation, cardiac resynchronisation therapy, percutaneous mitral annuloplasty and retrograde cardioplegia delivery require cannulation of the coronary sinus (CS). Detailed knowledge of the CS ostium region, including recognition of the presence of the Thebesian valve which sometimes covers the sinus, is a key to successfully carryout such procedures. In the present study, 160 autopsied human hearts from both sexes were examined for the presence of the Thebesian valve. If identified, the histological structure of the valve was studied. Five types of the CS valve were distinguished; all of them presented with a typical histological structure with the exception of the cord-like type, in which cells were similar to those of the conduction system of the heart. Proper identification of the CS valve and analysis of its size and histological features could have important implications for electrophysiologists.

Bachmann's bundle and coronary sinus ostial pacing accentuate left atrial electrical dyssynchrony in an acute canine model.

In patients with intraatrial conduction delay and sinus node (SN) dysfunction, pacing Bachmann's bundle (BBR) and coronary sinus ostium (CSO) has been suggested to achieve atrial resynchronization with potential beneficial impact on atrial fibrillation and diastolic heart failure. Clinical studies have not shown superiority of one approach. We studied electrical activation sequence in an open-chest acute canine model of normal atrial function in 8 mongrel dogs under general anesthesia. Bipolar plunge electrodes were distributed over the surface of the atria during unifocal pacing, and intracardiac activation sequence was observed. SN pacing resulted in near-simultaneous activation at midline sites (BBR and CSO); the left atrium (LA) was activated by anterior and posterior wavefronts simultaneously propagating septally to laterally and meeting at the low-lateral perimitral LA. Right atrial appendage (RAA) pacing created intra-RA conduction delay and delayed onset of LA activation. Pacing from RAA, CSO, and BBR resulted in nonsimultaneous activation at midline sites and produced an anteroposterior gradient of LA activation. This phenomenon was seen to the greatest degree with midline pacing and shifted the site of latest activation away from the low-lateral perimitral LA in all pacing configurations except SN pacing. Pacing-induced intra-LA activation dispersion is enhanced with midline atrial pacing, and secondarily shifts the site of latest activation away from the lateral mitral annulus. Measuring atrial activation times to the low-lateral perimitral LA can underestimate the degree of atrial dyssynchrony and be misinterpreted as atrial synchrony. Establishing clinical impact requires evaluation of human data.

Assessment of the coronary venous system using 256-slice computed tomography.

PurposeTo investigate the coronary venous system and its relation to adjacent structures using 256-slice computed tomography (CT).Materials and MethodsThe study consisted of 102 patients who underwent coronary CT angiography (CTA) using 256-slice CT. For each patient, the coronary venous system and its relation to adjacent structures were evaluated. The appropriate locations and diameters of the posterior interventricular vein (PIV), posterior vein of the left ventricle (PVLV) and the left marginal vein (LMV) were detected. The paired student's t test was used to evaluate the difference between the diameter of the coronary sinus (CS) ostium in anteroposterior direction and that in superoinferior direction.ResultsThe CS, great cardiac vein (GCV), PIV, and anterior interventricular vein (AIV) were visualized in all cases. It was possible to evaluate at least one main vein with adequate caliber and regular course for cardiac resynchronization therapy (CRT) in 96.1% of these cases. The diameter of the CS ostium in superoinferior direction (11.7±2.1 mm) was larger than that in anteroposterior direction (9.0±2.0 mm) (t = 13.511, P<0.05). For the majority of the cases, the CS-GCV was located above the level of the mitral valve annulus (MVA), while the left circumflex coronary artery (LCX) was coursed between the CS-GCV and the MVA. LMV had more intersection with the circumflex or circumflex marginal than PVLV.Conclusion256-slice CT provides superior noninvasive evaluation of the coronary venous system which has important clinical implications.

Inducible Focal Atrial Tachycardia of Coronary Sinus Origin Masquerading as Ventricular Tachycardia

CASE: This is the case of a 35-year old male physician presenting with a 12-year history of palpitations despite oral metoprolol. He had reversible left hemiparesis with right hemispheric lacunar infarctions on computerized tomography scan. The 12-lead electrocardiogram (ECG) recorded during an episode of palpitations revealed wide QRS (0.16 s) tachycardia (heart rate=214 beats per minute) with left bundle branch block (LBBB) QRS morphology; no identifiable P waves; QS pattern in leads V1 to V4; RS pattern in leads V5 and V6; and a QRS axis at -1300. There were no AV dissociation; fusion and captured beats; and precordial QRS concordance. Electrophysiology studies (EPS) were performed. During programmed electrical stimulation (PES) at the right ventricular apex, sustained narrow QRS (0.10 s) tachycardia (168 bpm) was induced. Examination of the intracardiac atrial (A) and ventricular (V) electrograms during the tachycardia revealed a 1:1 AV relationship; closer A electrogram to the preceding A electrogram than the following V electrogram producing a short RP tachycardia (&lt;70 ms); variable VA intervals; VAAV response during ventricular overdrive maneuver, and termination of the tachycardia at the V electrogram. The above EP parameters favored a diagnosis of focal atrial tachycardia (FAT) over re-entrant supraventricular tachycardia (SVT). The earliest activation site of the induced SVT was recorded near the ostium of the coronary sinus (CS 9 and 10) which coincided with the findings on 3D mapping. DIAGNOSIS: FAT with acceleration-dependent functional LBBB based on a mechanism of triggered automaticity arising from the coronary sinus ostium. TREATMENT AND OUTCOME: Radiofrequency ablation was applied on the identified arrhythymogenic atrial focus and effectively restored sinus rhythm and rendered the FAT non-inducible.

Coronary sinus diameter by echocardiography to differentiate atrioventricular nodal reentrant tachycardia from atrioventricular reentrant tachycardia

Coronary sinus (CS) has been shown to be larger in patients with atrioventricular nodal reentrant tachycardia (AVNRT). We sought to determine if echocardiographically measured CS diameter can help identify the mechanism of tachycardia in patients with narrow complex tachycardia without preexcitation before the invasive electrophysiology study. Forty four patients with documented narrow complex, short RP tachycardia who were scheduled for an electrophysiology study were included. Based on the electrophysiology study, patients were divided into those with AVNRT and those with a concealed accessory pathway and atrioventricular reentrant tachycardia (AVRT). Proximal CS diameter (CSp) measured at the ostium and mid CS diameter (CSm) 1 cm distal to the ostium using transthoracic echocardiography. CSp was significantly larger in patients with AVNRT than AVRT (14.1 ± 5 vs. 9.9 ± 2 mm, p < 0.0001). CSm diameter was not significantly different between the two groups. A cut-off of CSp > 11.2 mm identified AVNRT with a sensitivity of 92.6% and specificity of 76.9%. CSp was a better discriminant (AUC 0.89, 95% CI 0.75-0.97) compared to age (AUC 0.74, 95% CI 0.58-0.87) or tachycardia rate (AUC 0.60, 95% CI 0.44-0.76). Echocardiographic measurement of the diameter of CS ostium can help in identifying the mechanism of the tachycardia before the invasive electrophysiology study.

Congenital anomalous coronary sinus ostium

Congenital anomalous coronary sinus ostium is extremely rare. We describe a case of congenital left atrial coronary sinus ostium in a patient scheduled for ablation for atrial fibrillation. The anomalous coronary sinus ostium was found when contrast was injected during the ablation procedure and was confirmed by cardiac computed tomography.

Eccentric activation of the coronary sinus during typical atrial flutter: What is the mechanism?

A 79-year-old man with a history of ventricular septal defect underwent catheter ablation of drug refractory paroxysmal atrial flutter (AFL). The 12-lead electrocardiogram during tachycardia showed a biphasic, predominantly positive flutter wave with an initial negative component in leads II, III, and aVF, and positive flutter waves in leads V1 through V6 (Fig. 1, A), consistent with typical counterclockwise (CCW) AFL [1]. A decapolar catheter was advanced with its ♯17 and ♯18 poles in the proximal coronary sinus (CS), and a deflectable duodecapolar Halo catheter was placed parallel to the tricuspid annulus (TA), across the inferior vena cava (IVC)-TA isthmus, with its tip at the CS ostium (Fig. 1, B and C). Although we did not perform contrast CS venography to confirm the location of the CS ostium, we believe that the CS ostium is located near the 5 o'clock position of the mitral annulus as estimated by the shape of the CS catheter projected in the left anterior oblique fluoroscopic view, consistent with the location of the ♯17 and ♯18 poles of the CS catheter. The atrial activation sequence along the TA during ongoing tachycardia, combined with entrainment pacing at the IVC-TA isthmus, and 10 o'clock and 2 o'clock positions of the TA with a pacing cycle length of 220 ms confirmed the diagnosis of typical CCW AFL. We did not perform entrainment pacing from the CS. During entrainment pacing from any site along the TA, all atrial deflections in CS recordings immediately after the last pacing stimulus were captured with the activation sequence similar to that during the AFL and a spikeatrial interval shorter than AFL cycle length, consistent with an orthodromic capture. A line of radiofrequency energy delivery blocked conduction across the IVC-TA isthmus, terminated AFL, and restored sinus rhythm. Differential pacing from the low septal and lateral right atrial (RA) region confirmed the successful creation of bidirectional isthmus block. It is noteworthy that, during ongoing AFL before ablation, (1) a latency of low RA conduction, consistent with conduction across the septal isthmus, was observed along the distal Halo catheter (Fig. 1, D), and (2) recording of atrial activation along the CS, instead of being proximal to distal, was centrifugal from CS poles 9 to 10 (Fig. 1, D). What is the underlying electrophysiological mechanism of atypical atrial activation during typical CCW AFL?

Demonstration of Anatomic Reentrant Circuit in Verapamil-Sensitive Atrial Tachycardia Originating from the Atrioventricular Annulus Other than the Vicinity of the Atrioventricular Node

The mechanism and tachycardia circuit of verapamil-sensitive atrial tachycardia originating from the atrioventricular annulus (AVA-AT) other than the atrioventricular node vicinity are not well clarified. In 23 patients, we examined the mechanism and anatomic tachycardia circuit of AVA-AT. While recording the atrial electrogram at the earliest atrial activation site (EAAS) during tachycardia, rapid atrial pacing at a rate 5 beats/min faster than the tachycardia rate was delivered from multiple sites of the right atrium (RA) to demonstrate manifest entrainment and define the direction of proximity of slow conduction area (SCA) of reentry circuit. When EAAS was orthodromically captured, radiofrequency energy was delivered starting at a site 2 cm away from the EAAS in the direction of entrainment pacing site. Then application site was gradually advanced toward the EAAS until termination of tachycardia to define the entrance of SCA of reentry circuit. Manifest entrainment was demonstrated in all AVA-ATs. The EAAS, distributed along the tricuspid annulus from 3- to the 12-o'clock position, was orthodromically captured by pacing delivered from high anterolateral RA (n = 6), high anteroseptal RA (n = 7), high posteroseptal RA (n = 3), low anterolateral RA (n = 6), and coronary sinus ostium (n = 1). Radiofrequency energy delivery to the site, 10.4 ± 2.4 mm proximal to the EAAS where the atrial electrogram was observed 13.9 ± 5.7 ms later than the EAAS, terminated AVA-AT immediately after the onset of energy delivery (2.9 ± 1.1 seconds). In conclusion, it was shown that the AVA-AT is organized as reentry involving the verapamil-sensitive SCA with its entrance and exit at different distinct locations.

The Prevalence of Coronary Sinus and Left Circumflex Artery Overlap in Relation to the Mitral Valve

Characterize where the circumflex artery crosses between the coronary sinus and mitral valve in order to minimize the occurrence of coronary compression during percutaneous indirect mitral valve interventions. Treatment of mitral valve regurgitation using an indirect percutaneous approach via access through the coronary sinus remains under active research and development. Characterization of anatomical locations where the circumflex artery crosses between the coronary sinus and mitral valve is important for mitigation of serious ischemic complications. Magnetic resonance images were obtained for 65 perfusion-fixed human hearts. Three-dimensional reconstructions of anatomical orientations of the coronary sinus, circumflex artery, and mitral valve annulus were generated. The prevalence and location of sites where the circumflex artery coursed between the coronary sinus and mitral valve were assessed. The circumflex artery coursed between the coronary sinus and mitral valve in 88% of specimens. Overlaps between the circumflex artery and coronary sinus were less prevalent more proximal to the coronary sinus ostium. The coronary sinus did not lie in the same plane as the mitral annulus in roughly 20% of the hearts. The prevalence of circumflex overlap between the coronary sinus and mitral valve was common across the sample size. The large variability in anatomy confirms the value of imaging individual patient cardiac anatomy prior to performing indirect percutaneous mitral valve annuloplasty to avoid impairment to the circumflex artery. This novel database can be utilized in the development of additional cardiac therapies that require access to the coronary sinus, such as therapeutic ablations.

Incessant long RP tachycardia: What is the mechanism?

Case presentation A 59-year-old woman with a history of palpitations and incessant narrow complex tachycardia was referred for electrophysiologic study and catheter ablation. Multipolar catheters were placed in the right atrium, His-bundle region, right ventricle, and coronary sinus (CS), with the proximal CS electrode positioned at the CS ostium. At baseline, the patient had incessant long RP tachycardia with negative P waves in the inferior and precordial leads. The tachycardia