Coronary Sinus Ostium Research Articles

Analysis of the Anatomical Tachycardia Circuit in Verapamil-Sensitive Atrial Tachycardia Originating From the Vicinity of the Atrioventricular Node

Calcium channel-dependent tissue has been suggested to be involved in the circuit of verapamil-sensitive atrial tachycardia originating from the atrioventricular (AV) node vicinity (V-AT), but little information exists. To examine the tachycardia circuit of V-AT, a single extrastimulus was delivered during tachycardia to 10 sites of the intraatrial septum: the earliest atrial activation site; His bundle (HB) site; 3 arbitrarily divided sites on the AV junction extending from the HB site to the coronary sinus ostium (CSOS) (sites S, M, and I); the internal-CSOS, inferior-CSOS, superior-CSOS, posterior-CSOS, and posteroinferior-CSOS in 10 patients with V-AT. The longest coupling interval that reset V-AT and subsequent return cycle were measured. The longest coupling interval at earliest atrial activation site was significantly longer than the longest coupling interval at the HB site, site S, M, and I, internal-CSOS, inferior-CSOS, superior-CSOS, posterior-CSOS, and posteroinferior-CSOS, respectively (P<0.001 for HB site and P<0.0001 for the remaining 8 sites). The return cycle at earliest atrial activation site did not differ from the tachycardia cycle length, whereas those at the remaining 9 sites were significantly longer than tachycardia cycle length (P<0.001). Furthermore, a single extrastimulus delivered from sites inferior to the HB site advanced His potential without resetting V-AT in 7 patients in whom AV block was not observed during tachycardia. Atrial tissue within the Koch's triangle extending from the HB site to posteroinferior-CSOS is not involved in the tachycardia circuit. Verapamil-sensitive atrial tissue close to the AV node but not the AV nodal conducting system forms the tachycardia circuit of V-AT.

Primary Prevention of Atrial Fibrillation: Does the Atrial Lead Position Influence the Incidence of Atrial Arrhythmias in Patients with Sinus Node Dysfunction? Results from the PASTA Trial

PASTA (pacing of the atria in sinus node disease) is a prospective and randomized trial, assessing the effect of different atrial lead positions on the atrial fibrillation (AF) incidence in patients with sinus node disease (SND). The atrial lead position is randomized to: (a) free right atrial wall, (b) right atrial appendage (RAA), (c) coronary sinus ostium (CS-Os), or (d) dual site right atrial pacing (CS-Os + RAA). The pacemakers (Vitatron Selection 9000 or Prevent AF, Vitatron B.V., Arnhem, The Netherlands) are programmed in DDDR 70 mode and the total follow-up duration is 24 months. To describe the atrial rhythm state, pacemaker-derived data (arrhythmia counter) were assessed for AF episodes. AF was considered as evident, if the AF burden (time in AF related to follow-up interval) was >1% (i.e., 15 min/d). Follow-up data after 24 months were evaluated. The analysis evaluates 142 patients (77 male, 74.5 +/- 7.8 years). There was no statistical significant difference with respect to the occurrence of AF between the four groups after 24 months (A: 36%; B: 38%, C: 32%, D: 48%). The percentage of atrial/ventricular pacing was in A: 78/76%, in B: 84/81%, in C: 70/65%, and in D: 79/69%. These differences were not significant. The evaluation of the AF burden >1% and the total AF burden after 24 months did not show differences in the incidence of AF in patients with dual chamber pacemaker therapy for SND. We were not able to demonstrate a significant influence of right atrial lead position on the incidence of AF recurrence.

Atresia of the Coronary Sinus Ostium to the Right Atrium with a Persistent Left Superior Vena Cava

El seno coronario recientemente ha asumido un papel importante en la clinica cardiologico, siendo ampliamente utilizado en procedimientos invasivos del corazon. Comunmente, se utiliza en los implantes de los electrodos para el monitoreo epimiocardico del ritmo cardiaco, a traves de un ritmo biventricular establecido. Estos procedimientos invasivos no son posibles en los corazones con una atresia del ostium del seno coronario. En presencia de esta condicion, se puede producir otra anomalia: el desarrollo de la vena de Marchal la cual es un vestigio de la vena cava superior izquierda (VCSI). Esto provoca que la sangre venosa del corazon pueda drenar en el atrio derecho, por una comunicacion entre la VCSI y la vena braquicefalica izquierda. La presencia de una VCSI trae dificultades a la hora de realizar un procedimiento invasivo con el fin de acceder al atrio derecho a traves de la vena cava superior, usualmente hecho en la clinica cardiologica. Por otra parte, el cruzamiento de la VCSI sobre el atrio izquierdo es vulnerable en las intervenciones quirurgicas cardiovasculares, confirmado por informes clinicos. En el presente estudio, 400 corazones fijados en formalina provenientes a cadaveres de sexo masculino, con edades comprendidas entre los 35 y 80 anos, fueron investigados, en particular por la anatomia del seno coronario. El ostium obliterado del seno coronario al atrio derecho asociado con una VCSI persistente estuvo presente en solo una muestra (0,25%). Se realizo un estudio del diametro de estas estructuras dilatadas debido a que la sangre venosa drena desde el corazon hacia el atrio derecho, por una comunicacion entre la VCSI y la vena braquicefalica izquierda. Tambien se realiza una revision de la literatura de estos casos y se discuten nuestros hallazgos en relacion con su importancia clinica.

Extracardiac structures are frequently present within close proximity to the left atrium: Relevance to catheter ablation

The coronary sinus (CS) including the great cardiac vein is an important anatomic structure that is considered a landmark for the mitral annulus (MA) and also a target for catheter ablation. This study evaluated the anatomical relationship between the CS and its surrounding structures visualized by multi-detector computed tomography (MDCT). We performed MDCT on 42 patients, and the ranges of the coronary arteries (CAs) and esophagus that ran closest (<5 mm) to the CS were examined. In addition, the distances between the CS and the MA and left ventricle and left atrium were compared with the amplitudes of the local atrial and ventricular electrograms in the CS at the most lateral point (3 o'clock) and the inferior point (6 o'clock) in the CS. The distal portion of the right CA ran near the antero-inferior side of the CS ostium in 92% of the patients. The esophagus and the left circumflex CA proximity to the CS ran from 15 to 41 mm and from 53 to 104 mm from the ostium in all patients. At the 3 o'clock and 6 o'clock position of the MA, the distance between the center of the CS and MA was 12 and 13 mm, respectively, and showed negative correlation with the ratio of atrial and ventricular electrograms. The right CA, the left circumflex CA, and the esophagus were frequently located near the CS. The CS was shifted away from the MA, and the CS-MA distance could be predicted with intracardiac electrograms.

The cardiac veins in congenitally corrected transposition of the great arteries: Delivery options for cardiac devices

Device implantation is sometimes required in congenitally corrected transposition of the great arteries (ccTGA) because of morphologic right ventricular (RV) dysfunction and complete heart block. The anatomical course of the veins remains unknown, despite well-described coronary arterial anatomy. Knowledge of the venous anatomy may facilitate planning of percutaneous cardiac procedures in these patients. This study sought to characterize the venous anatomy in ccTGA. Pathologic cardiac specimens from patients with ccTGA were identified from the Mayo Clinic pathology database. Coronary sinus (CS) anatomy and distances from the CS ostium to the major cardiac veins were evaluated. Thebesian veins with ostial openings >1 mm, epicardial veins, and venous collaterals were also quantified. There were 56 hearts with a diagnosis of ccTGA identified. The CS was unidentifiable in 5 hearts due to slicing, and assessment of the Thebesian veins was not possible in 16. Seven hearts had an abnormal CS, 2 of which had atretic ostia and the other 5 of which either had an abnormal ostial location or multiple ostia. There were 28 hearts with at least 1 Thebesian vein with an ostial opening >1 mm. All 12 hearts with unidentifiable Thebesian veins had venous collaterals from the right ventricle (RV) to the major cardiac veins. Epicardial veins extended to the proximal, middle, and distal thirds of the RV in 71%, 23%, and 6%, respectively. In ccTGA, the ventricular venous anatomy is abnormal and follows the morphologic RV. However, large interventricular and Thebesian veins may offer options for percutaneous lead or catheter placement when approaching the systemic RV.

Variations in Thebesian valve anatomy and coronary sinus ostium: implications for invasive electrophysiology procedures

The coronary sinus (CS) is a commonly cannulated structure in patients undergoing electrophysiology studies, catheter ablation of arrhythmias, implantation of resynchronization therapy devices and, more recently, percutaneous mitral valve repair. The advent of these procedures has led to a renewed interest in the anatomy of the coronary venous system including its various components. To improve our understanding of this structure, we studied the anatomy of the human CS, including the valve that guards its ostium, the Thebesian valve. In 75 randomly selected autopsied human hearts, we measured the transverse and craniocaudal dimensions of the CS ostium and characterized the shape, composition, per cent coverage, and attachment points of the Thebesian valve when present. Of the 75 hearts examined, 54 had organic heart disease including atherosclerotic coronary artery disease, left ventricular hypertrophy, dilated cardiomyopathy, rheumatic heart disease, infective endocarditis, and non-rheumatic valvular heart disease. A wide variety of Thebesian valve morphologies were seen, ranging from the absence of any valve to those where the valve was completely occluding the CS ostium. A Thebesian valve was present in the majority of the hearts examined (55/75 hearts-73%). The average transverse dimension of the CS ostium in hearts with Thebesian valves (7.3+/-2.8 mm) was significantly shorter than those without Thebesian valves (9.4+/-2.9 mm, P=0.005). Similarly, the average craniocaudal dimension of the CS ostium in hearts with Thebesian valves (7.9+/-2.7 mm) was also significantly shorter than those without Thebesian valves (9.3+/-2.9 mm, P=0.045). Our study shows that some form of Thebesian valve is present in the majority of hearts (>70%). Of these, a significant minority (16%) had a valve morphology (covering >75% of the ostium, a fibrous, fibromuscular, or muscular composition, and devoid of fenestrations) that makes them a 'potentially complicating' structure interfering with the cannulation of the CS.

Rare Case of an Unroofed Coronary Sinus

A 53-year-old man presented to our hospital with acute coronary syndrome and underwent uncomplicated cardiac catheterization with percutaneous coronary intervention. As part of an institutional research protocol for evaluation of the recently placed left circumflex stent, he underwent coronary CT angiography with ECG-gated, contrast-enhanced, 64-slice multidetector CT (Sensation Cardiac 64, Siemens Medical Solutions, Forchheim, Germany). An incidental note of an unroofed coronary sinus (CS) was made on the coronary CT angiogram (Figure 1A through 1D). The defect size measured by CT was 2.1×0.4 cm, and its distance from the CS ostium was 2.1 cm. In addition to its normal connection to the right atrium, the CS had a direct connection with the left atrium (LA) as noted by the contrast shunting from the LA into the CS and subsequently into the right atrium (Figure 1D). No other congenital anomalies, including persistent left superior vena cava (LSVC), were identified on the CT. Clinically, the patient had no prior history of strokes, hypoxia, or heart failure symptoms. His 12-lead surface ECG (Figure 2) showed normal sinus rhythm without evidence of chamber enlargement. The chest topogram from the CT …

Atrial Electromechanical Sequence and Contraction Synchrony during Single‐ and Multisite Atrial Pacing in Patients with Brady‐Tachycardia Syndrome

Investigation of which atrial pacing modality provides atrial synchrony and the most physiological atrial contraction pattern in patients with brady-tachycardia syndrome. Fifteen healthy subjects and 57 patients with sinus node dysfunction, atrial fibrillation recurrences, and prolonged P-wave on the electrocardiogram treated with multisite atrial (MSA) pacing were studied. One atrial lead was implanted in the coronary sinus (CS) ostium area, the other at the right atrial appendage (RAA): RAA+CS group (28 patients), or Bachmann's bundle (BB) region: BB+CS group (29). Sinus rhythm (SR) and CS, RAA, BB, RAA+CS, and BB+CS pacing modalities were evaluated. Electromechanical delay (EMD) in atrial walls was assessed by tissue Doppler echocardiography. Interatrial (DeltainterA), intra-right (DeltaRA), and intra-left (DeltaLA) atrial dyssynchrony were calculated. During SR, in the study group versus controls, important DeltainterA: 55 +/- 23 versus 22 +/- 11 ms (P < 0.01) and DeltaLA: 47 +/- 21 versus 21 +/- 6 ms (P < 0.001) were present. Single-site BB and both MSA pacing modes restored DeltainterA and DeltaLA (DeltainterA: 24 +/- 16, 20 +/- 13 and 14 +/- 9 ms, DeltaLA: 28 +/- 18, 28 +/- 13 and 20 +/- 10 ms during BB, RAA+CS and BB+CS pacing, respectively). CS pacing prolonged lateral RA EMD, while RAA pacing LA walls EMD, which resulted in DeltainterA persistence. CS pacing induced DeltaRA (50 +/- 23 vs 16 +/- 8 ms, P < 0.0001 vs controls). Atrial contraction sequence during BB pacing resembled that observed in controls. (1) Single-site BB and both MSA pacing modes restored atrial synchrony. (2) Single-site RAA and CS ostium pacing retained interatrial dyssynchrony; moreover, CS pacing created RA dyssynchrony. (3) Single-site BB pacing provided physiological atrial contraction sequence.

Percutaneous Treatment of Mitral Regurgitation

Percutaneous mitral valve therapy became a reality more than 25 years ago with the first description of balloon valvuloplasty for rheumatic mitral stenosis.1 More recently, percutaneous closure of paravalvular leaks after surgical valve implantation has been shown to have a potential, but limited, role.2–4 However, valvular mitral regurgitation (MR) remains largely the purview of surgery. Recently, the potential for less invasively replicating these successful surgical procedures without the need for thoracotomy or cardiopulmonary bypass has generated considerable interest. For the most part, these new approaches are modeled after established surgical strategies. Percutaneous approaches to mitral repair can be broadly divided into procedures that address the various components of the mitral valve. For purposes of discussion, the mitral valve can be considered to have several component parts: leaflets, subvalvular apparatus (chordate tendinae and papillary muscles), annulus, left atrium, and left ventricle.5 All are integral to the normal function of the mitral valve and each is a potential avenue for repair. Although many such avenues may not lead to an effective surgical option, it may be unwise to dismiss the possibility that others will achieve some measure of success. We briefly review the current percutaneous therapies being developed and evaluated for the management of MR. The current status of various percutaneous therapies is presented in Table 1. View this table: Table 1. Current Status of Percutaneous Mitral Valve Repair Procedures ### Leaflet Repair Complex leaflet repair is currently beyond the reach of a percutaneous approach. However, the relatively simple but, in selected patients, effective “double-orifice” surgical repair initially described by Alfieri and coworkers6 can be reproduced. In the surgical procedure, the free edges of the mitral leaflets are sutured together in the mid portion creating 2 separated orifices. Generally, surgical leaflet repair is combined with implantation of an annuloplasty ring. The surgical literature …

Analysis of Atrioventricular Nodal Reentrant Tachycardia with Variable Ventriculoatrial Block: Characteristics of the Upper Common Pathway

The precise nature of the upper turnaround part of atrioventricular nodal reentrant tachycardia (AVNRT) is not entirely understood. In nine patients with AVNRT accompanied by variable ventriculoatrial (VA) conduction block, we examined the electrophysiologic characteristics of its upper common pathway. Tachycardia was induced by atrial burst and/or extrastimulus followed by atrial-His jump, and the earliest atrial electrogram was observed at the His bundle site in all patients. Twelve incidents of VA block: Wenckebach VA block (n = 7), 2:1 VA block (n = 4), and intermittent (n = 1) were observed. In two of seven Wenckebach VA block, the retrograde earliest atrial activation site shifted from the His bundle site to coronary sinus ostium just before VA block. Prolongation of His-His interval occurred during VA block in 11 of 12 incidents. After isoproterenol administration, 1:1 VA conduction resumed in all patients. Catheter ablation at the right inferoparaseptum eliminated antegrade slow pathway conduction and rendered AVNRT noninducible in all patients. Selective elimination of the slow pathway conduction at the inferoparaseptal right atrium may suggest that the subatrial tissue linking the retrograde fast and antegrade slow pathways forms the upper common pathway in AVNRT with VA block.

Interatrial right-to-left conduction in patients with paroxysmal atrial fibrillation

We wanted to illustrate the right-to-left impulse propagation routes during sinus in patients with paroxysmal atrial fibrillation (PAF), as alterations in conduction patterns have been linked to the pathogenesis of PAF, and as no large patient materials have been published. Patients underwent 3-D electroanatomical contact mapping prior to catheter ablation. The site of the earliest left atrial (LA) activation was determined. Three different interatrial routes were identified, either as solitary pathways (36/50 patients, 72%) or in their combinations (14/50). Bachmann's bundle (BB) was involved in the majority of the cases with solitary routes (25/36). More seldom, impulse propagation occurred near the oval fossa (FO) (7/36) or the coronary sinus ostium (4/36). In patients with combined routes, both the BB (10/14) and FO routes (11/14) were included in most cases. In PAF patients, LA can be activated during sinus rhythm through three distinct connections, either encompassing a single route or via any combination of these connections. In one third, the earliest LA activation occurs outside BB. The knowledge of the propagation patterns may give insight into the pathophysiology of PAF and into refining ablation therapy.

Ventricular location of a part of the right atrial isthmus after tricuspid valve replacement for Ebstein’s anomaly: a challenge for atrial flutter ablation

We report the case of a patient with atrial flutter late after tricuspid valve replacement for Ebstein's anomaly. Computed tomographic angiography revealed that coronary sinus ostium and part of the right atrial isthmus were located on the ventricular side of the valve ring due to the specific surgical approach in this condition. Based on the results of electroanatomic mapping and entrainment, the arrhythmia was found to be cavotricuspid isthmus dependent clockwise atrial flutter. Completion of the isthmus line required ablation lesions across the artificial valve. When these were delivered the arrhythmia terminated and isthmus block was achieved. Due to arrhythmia recurrence a redo procedure was performed which demonstrated conduction recovery in the ventricular part of the cavotricuspid isthmus. Intracardiac ultrasound-guided ablation successfully eliminated conduction across the isthmus with subsequent freedom from arrhythmia on follow up.

Atrioventricular node anatomy and physiology: implications for ablation of atrioventricular nodal reentrant tachycardia

Atrioventricular nodal reentrant tachycardia (AVNRT) is the most common arrhythmia in patients with regular supraventricular tachycardia. Selective radio frequency catheter ablation of the slow pathway has afforded an ideal method to treat most patients with AVNRT. However, there are still some controversies and recent developments concerning the ablation for patients with AVNRT. The purpose of this review is to elucidate the anatomy and physiology of the atrioventricular node and implications for the ablation of AVNRT. The sequential ablation sites for slow pathway ablation are suggested as the isthmus between tricuspid annulus and coronary sinus ostium, the tricuspid edge of coronary sinus ostium by moving the ablation catheter tip slightly in and out of the coronary sinus, the septum lower than coronary sinus ostium, moving higher up on the half of Koch's triangle along the septum, one or two burns inside the first centimeter of the coronary sinus, left side of the septum. It is imperative to recognize the detailed anatomy and physiology of the atrioventricular node in every individual patient before the ablation of AVNRT.

Concomitant giant coronary artery and coronary sinus aneurysms

consecutive reoperations were needed because of recurrent prosthetic dehiscence and mitral valve dysfunction. It was considered that a mitral homograft could be a valid alternative, but functional results were disappointing because of limited mobility and deficient coaptation of the anterior leaflet. Implantation of an annuloplasty ring and repair of the valve commissure were unsuccessful, and instead of explanting the homograft it was decided to remove the annuloplasty ring and insert a bioprosthesis in a transvalvular position, with the homograft acting as a native valve. At 14 months of follow-up, the patient is free of symptoms, and functional results are satisfactory. Hypersensitivity to the suture ring of the valve prosthesis is an appealing explanation for our findings. In this respect, the interposed homograft avoided the potential risk of intolerance to the suture ring and also prevented direct contact between the infected tissue and the prosthesis.

Backup Right Ventricular Pacing with a 0.035″ Guidewire during Implantation of Left Ventricular Leads

During implantation of biventricular devices, manipulation of the guiding sheath during localization of the coronary sinus (CS) ostium may result in injury to the right bundle and complete heart block. A preventive measure is to implant the right ventricular (RV) lead first, though this may interfere with manipulation of the guiding sheath and dislodge the permanent lead. We tested the feasibility of backup pacing with a 0.035'' guidewire, advanced through the guiding sheath during CS localization. One hundred six consecutive patients (mean age = 70 +/- 11 years, 81 men) undergoing biventricular device implantation were studied. A 0.035'' guidewire with an uncoated tip was advanced into the right ventricle through the guiding sheath, and unipolar capture threshold, R-wave sensing amplitude, and pacing impedance were measured. RV pacing was successful in all patients. The mean capture threshold was 3.8 +/- 2.1 V/0.5 ms, R-wave amplitude 5.4 +/- 4.3 mV, and pacing impedance 226 +/- 78 Omega. No arrhythmia was observed during the tests. Two patients developed complete heart block during the implant procedure and were successfully paced temporarily using the 0.035'' guidewire. Temporary RV pacing, using a 0.035'' guidewire within the guiding sheath, is a simple, reliable, and safe method that allows backup pacing in case of traumatic complete heart block, developing during the implantation of biventricular devices.

The relationship between the coronary sinus and coronary artery using multislice spiral computed tomography and conventional invasive angiography

Background Multislice computed tomography (MSCT) has been used extensively for coronary artery imaging. To understand the relationship between coronary artery and coronary sinus (CS) anatomy in patients undergoing electrophysiological study, conventional invasive angiography is typically performed. The purpose of this study was to image the coronary artery and CS and its tributaries using MSCT, in comparison with invasive angiography. Methods and results The study consisted of 141 patients (83 men, 58 women; age 52 ± 10 years) who underwent 64-slice MSCT and 3D reconstruction and invasive coronary artery and CS angiography before radiofrequency catheter ablation. The cardiac venous system and coronary artery were visualized in all patients by MSCT and invasive angiography. All data of angiography and MSCT were measured via the same projection (right or left anterior oblique). Angiography and MSCT result revealed coronary arteries of all patients with a vessel diameter over 1 mm. The CS and the middle cardiac vein (MCV) were observed in all patients. MSCT provided high accuracy for the MCV to the CS ostium (CSO), the posterior interventricular vein (PIV) to CSO, and the mean diameter of MCV, PIV and CS ostia, compared with invasive angiography ( p < 0.001). Conclusions MSCT was a reliable tool to visualize the relationship between the coronary artery and CS and its tributaries. MSCT may improve the procedural success rate and reduce the complication rate in patients undergoing electrophysiological study.

Atrial Function During Different Multisite Atrial Pacing Modalities in Patients With Bradycardia - Tachycardia Syndrome

Multisite atrial pacing (MAP) was introduced to improve atrial electrical synchrony and prevent recurrence of atrial fibrillation (AF). In the present study there were 57 patients with sinus node disease, AF recurrence and prolonged P-wave on ECG with 2 MAP modalities. In all patients 1 lead was implanted in the coronary sinus (CS) ostium area. In the right atrial appendage (RAA)+CS group (28 patients) the other atrial lead was in the RAA, and in the BB+CS group (29 patients) in the Bachmann's bundle (BB) region. Tissue Doppler was used to register the electromechanical delay (EMD) in the atrial walls and estimate the atrial contraction synchrony. Cardiac output and myocardial performance index did not differ during the 2 MAP modalities. During BB+CS, in comparison with RAA+CS pacing, the peak of the mitral atrial wave occurred earlier (P<0.01), the usual right-left atrial contraction sequence was reversed more frequently (P<0.004), all atrial EMDs except for the lateral left atrium (LA) were shorter (P<0.05), and LA synchrony was greater (P<0.001). In patients treated with MAP, implanting 1 of the atrial leads in the BB area instead of the RAA has no influence on global cardiac hemodynamics, but does result in earlier LA contraction, and reversal of the typical right-left atrial contraction sequence, as well as providing greater LA contraction synchrony.

Aortic Valve Replacement for Aortic Stenosis During Orthotopic Cardiac Transplant

Although concomitant coronary bypass, and mitral and tricuspid valve surgery have been used to expand the donor pool for cardiac transplantation, aortic valve disease is considered an absolute contraindication for use of an offered organ. A case is presented with the successful use of an organ requiring concomitant aortic valve replacement for calcific aortic stenosis on a congenitally bicuspid valve. Eighteen-month follow-up documented excellent allograft function with a normally functioning mechanical aortic prosthesis. Aortic valve disease in offered organs can be successfully treated with aortic valve replacement at the time of transplantation and should not preclude the use of the organ in the setting of a recipient who is a candidate for a marginal allograft.

A 'Regularly Irregular' tachycardia: what is the diagnosis?

We report the case of a 46-year-old female presented to the emergency room with sustained palpitations. Her ECG showed a narrow QRS regularly irregular tachycardia. This tachycardia was immediately terminated by a single dose of adenosine, and sinus rhythm was restored. Diagnosis of atrial tachycardia, orthodromic reciprocating tachycardia, and atrial nodal reentrant tachycardia (AVNRT) are discussed. An electrophysiological study was performed for further evaluation, and our final hypothesis was AVNRT with triple nodal pathways. A single application of radiofrequency energy in the posterior septum near the coronary sinus ostium effectively eliminated the tachycardia.

Effects of inadvertent atrioventricular block on clinical outcomes during cryoablation of the slow pathway in the treatment of atrioventricular nodal re-entrant tachycardia

The study aimed at evaluating the long-term effects of transient atrioventricular (AV) block on clinical outcomes during atrioventricular nodal re-entrant tachycardia (AVNRT) cryoablation. In 150 consecutive patients (39 +/- 14 years, ineffective anti-arrhythmic drugs 1.9 +/- 1.3), slow-pathway cryoablation for AVNRT was performed. A 7 Fr 6 mm-tip cryocatheter was used. After successful cryomapping (-30 degrees C), defined as jump abolition or AV nodal refractory period prolongation, cryoablation (-80 degrees C for 4 min) was applied if no AV block occurred. Atrioventricular nodal re-entrant tachycardia inducibility was checked after 30 min. Acute success (AVNRT non-inducibility) was achieved in 142 patients (95%). Overall, after a follow-up of 18 +/- 10 months, 118 of 150 patients (79%) were recurrence-free (including 2 patients for whom the procedure was unsuccessful). Among successful procedures, 116 of 142 (82%) patients were recurrence-free. During cryoablation, inadvertent transient AV block of varying degrees occurred in 34 patients (22.7%), namely, increased PR in 17 patients and a 2nd-3rd AV block in the remaining 17. In 24 patients, AV block occurred at the last effective site (increased PR in 13 patients and a 2nd-3rd AV block in 11). In the study population as a whole, univariate predictors of recurrence in the follow-up were AVNRT inducibility (P < 0.001), increased PR at the last effective site (P < 0.001), residual jump (P < 0.02), and small Koch's triangle (X-ray distance < 11 mm between the His and coronary sinus ostium catheters; P < 0.02). Atrioventricular nodal re-entrant tachycardia inducibility (P < 0.03), increased PR (P < 0.01), and small Koch's triangle (P< 0.04) were independently significant. For attempts at the last effective site, 3 groups of patients were compared: 13 patients with increased PR duration (Group A), 11 with a 2nd-3rd AV block (Group B), and 126 without AV block (Group C). Cryo-application time was 277 +/- 203 s in Group A, 75 +/- 87 s in Group B, and 253 +/- 135 s in Group C (A vs. B, P < 0.01; B vs. C, P < 0.001; and C vs. A, P= NS). There was no statistical difference among groups in the atriogram/ventriculogram amplitude ratio at the site of the last attempt, unsuccessful acute procedure, small Koch's triangle, and residual jump. Actuarial incidence of recurrence-free status at 12 months was 38% in A, 82% in B, and 82% in C (A vs. B, P < 0.05; B vs. C, P = NS; and C vs. A, P < 0.001). All AV blocks occurring during cryoablation were transient, confirming the safety of this method. An increased PR duration at the last effective site is associated with a higher recurrence rate, whereas a 2nd-3rd degree AV block has a recurrence rate similar to that of patients without AV block despite a shorter cryo-application time at the last site.