Pre-excitation due to accessory sinoventricular connexions associated with coronary sinus aneurysms. A report of two cases

Atretic Coronary Sinus Orifice and a Diverticulum of Coronary Sinus Associated with Persistent Left Superior Vena Cava and Accessory Pathway

Coronary orifice atresia and diverticula are considered rare congenital conditions. Our understanding of the coronary sinus (CS) and venous drainage anatomy plays a crucial role in performing interventions and surgical procedures required to improve treatment options and related prognosis for these patients. The case study described herein involves a 29-year-old female patient who was diagnosed with coronary orifice atresia and diverticula. The patient's electrocardiography revealed normal sinus rhythm, short PR interval, and delta wave. Transthoracic echocardiography results showed the subject also suffered from mild CS dilation associated with coronary orifice atresia and diverticula. Our clinical intervention included the use of agitated saline injection which was administered intravenously into the patient's left arm. Our clinical observations during the administration of agitated saline solution did not indicate the presence of any detectable air bubbles entering into the CS. The results of two-dimensional and color flow Doppler study showed that CS connection to the right atrium appeared to be atretic. During our examination, we were also successful in detecting a pulsatile free echo space which was connected through an isthmus to the CS. Electrophysiology study and coronary angiogram performed on the subject confirmed our clinical diagnosis and findings of CS atresia, diverticula, and left superior vena cava.

Anatomy of the Atrioventricular Junction, Atrioventricular Grooves, and Accessory Pathways

Accessory pathways that bypass all or part of the normal atrioventricular conduction system traverse the atrioventricular junction. The atrioventricular junction comprises of a limited septal component and much more extensive right and left parietal components. Its composition forms a plane of insulation between atrial and ventricular myocardium, preventing direct continuity between them. Typical accessory atrioventricular pathways located anywhere along the atrioventricular junction are muscle bundles or may involve muscle around the walls of coronary sinus aneurysms or coronary veins. Increasingly, variants or unusual accessory pathways, some involving an accessory node, are reported in clinical studies.

Ablation of Accessory Pathways with Challenging Anatomy

Although catheter ablation of accessory pathways is deemed highly safe and effective, peculiar location of these pathways might lead to complex and potentially hazardous procedures requiring ablation in anatomic regions such as para-Hisian area, coronary sinus, and epicardial surface. The electrophysiologist should know these possible scenarios to plan the best strategy for safe and effective ablation of these uncommon accessory pathways.

Coronary sinus diverticulum: Importance, function, and treatment

The importance of venous structure in the heart is usually overshadowed by that of the arterial system. Coronary sinus (CS) is a part of cardiac venous apparatus and connects left atria to the right atria. Other than having role in physiological contractions of both atria, it contributes substantially to cardiac electrical conduction system. Due to unique placement and connections of the CS, it has become growing interest in clinical cardiology. It is used in cardiac resynchronization therapy with biventricular pacing, left-sided catheter ablation of arrhythmias, and administration of retrograde cardioplegia in cardiac surgery. In some individuals, CS is presented with anatomical variants. CS diverticulum is a congenital outpouching that provides muscular connection between atria and ventricle. This connection provides a suitable substrate for occurrence of arrhythmias, which even results in life-threatening events such as sudden cardiac death. Early diagnosis leads to treatment with ablation techniques, which ultimately eliminates origins of arrhythmias.

Surgical Treatment of Idiopathic Enlargement of the Right Atrium

Idiopathic enlargement of the right atrium (IERA) is a very rare abnormality. Approximately one-half (48%) of the patients with a congenital enlargement of the right atrium have no symptoms. When they occur, symptoms include shortness of breath (28% of cases), palpitations (17%), arrhythmias (12%), and in rare cases, right heart failure and extreme tiredness. We report one such case of a young man with a disproportionally enlarged right atrium. The basal transthoracic echocardiogram demonstrated a huge right atrium with a thick smoke pattern and mild tricuspid regurgitation in the absence of congenital heart disease. Magnetic resonance imaging confirmed the right atriomegaly, with initial compression of the right ventricle, and excluded congenital heart defects or absence of pericardium. The patient underwent surgical resection of the right atrial wall and the atriotomy was closed, leaving an atrial chamber of normal consistency and size. The resected atrium had normal and homogeneous wall thickness without significant fibrosis which confirmed the diagnosis of an idiopathic enlargement of the right atrium.

Simultaneous presentation of giant aneurysms of the coronary sinus and superior vena cava

Aneurysms of the coronary sinus and superior vena cava are rare and their aetiologies remain controversial. Some studies have shown that these acquired venous aneurysms are caused by an increase in right atrial pressure, which may be related to right heart failure. However, few reports have provided direct evidence to support this hypothesis. We present a rare case of combined giant aneurysms of the coronary sinus and vena cava, diagnosed using multiple imaging modalities. This case strongly supports the hypothesis that right heart diastolic failure may be an important mechanism underlying the pathogenesis of combined giant aneurysms.

Radiofrequency ablation for pre-excitation syndromes and AV nodal re-entrant tachycardia

Radiofrequency catheter ablation for supraventricular tachycardia was introduced in 1990. Since then it has become the standard for definitive treatment of pre-excitation syndromes and atrioventricular re-entrant tachycardia. In general, catheter ablation of supraventricular tachycardia results in improved outcomes compared to pharmacologic treatment. Over 95% of patients will be successfully treated with catheter ablation with less than a 5% chance of recurrence and <1% risk of major complications.

Histopathology of the Cardiac Conduction System in the Investigation of Sudden Unexpected Death

When a gross and microscopic autopsy, drug screen, and past medical history fail to yield a cause of death, the forensic pathologist may opt to study the cardiac conduction system. This paper describes the excision of the SA (sinoatrial) node and AV(atrioventricular) node-containing areas of the heart and the microscopic appearance of normal SA and AV nodes, His bundle and bundle branches. Conduction system findings that have been reported to be significant include fibromuscular hyperplasia (often mislabeled dysplasia) of the SA and AV nodes arteries, persistent fetal dispersion of the AV node and His bundle, accessory pathways, ganglionitis and neuritis near the SA node, fibrosis and fatty infiltration of the conducting tissue, AV node tumor, left-sided His bundle, and AV node fibrosis. In an otherwise normal autopsy, AV node tumors, severe fibromuscular hyperplasia of the AV node artery and AV node fibrosis are sufficient to cause death. Other findings, particularly Mahaim tracks, are competent causes of death if they correlate with premortem electrocardiographic findings. Conduction system examination, although a low-yield procedure, is a worthwhile endeavor. Care must be taken to not overestimate the significance of the findings.

Aneurysm of the great cardiac vein

Anatomical variations in the cardiac veins have the potential to cause iatrogenic injuries during cardiac surgical procedures or cardiac resynchronization therapy. We present a case of an 86-year-old man, which presented with a great cardiac vein aneurysm. The great cardiac vein arose near the apex of the interventricular sulcus to the right of the anterior interventricular branch (AIB) of the left coronary artery and crossed the AIB anteriorly to the left. The great cardiac vein aneurysm appeared to be due to a possible distal constriction of the great cardiac vein by a small muscular branch of the circumflex branch and a possible proximal constriction by the left marginal artery. Cardiologists who interpret imaging of the cardiac veins and cardiac surgeons who operate close to the great cardiac vein should be aware of such a variation.

Focal Atrial Tachycardia From the Ostium of the Coronary Sinus

OBJECTIVES

The goal of this study was to characterize the electrocardiographic and electrophysiologic features and frequency of focal atrial tachycardia (AT) originating from the coronary sinus ostium (CS).

BACKGROUND

The ostium of the coronary sinus has been described as a site of origin of AT, but detailed characterization of these tachycardias is limited.

METHODS

Thirteen patients (6.7%) of 193 undergoing radiofrequency ablation (RFA) for focal AT are reported. Endocardial activation maps (EAM) were recorded from catheters at the CS (10 pole), crista terminalis (20 pole), and His positions. The P waves were classified negative, positive, isoelectric, or biphasic.

RESULTS

The mean age was 41 +/- 6 years, seven female patients, with symptoms for 8 +/- 3 years. Tachycardia was induced by programmed extra-stimuli in eight patients, was spontaneous in three patients, and in response to isoproterenol in two patients. These foci had a characteristic P-wave morphology. At the CS ostium, the P-wave was deeply negative in all inferior leads, negative or isoelectric becoming positive in lead V(1), then progressively negative across the precordium. Lead aVL was positive in all patients. Earliest EAM activity occurred at the proximal CS at 20 +/- 3 ms ahead of P-wave. Mean activation time at the successful RFA site = -36 +/- 8 ms; RFA was acutely successful in 11 of 13 patients. Long-term success was achieved in 11 of 11 over a median follow-up of 25 +/- 4 months.

CONCLUSIONS

The CS ostium is an uncommon site of origin for focal AT (6.7%). It can be suspected as a potential anatomic site of AT origin from the characteristic P-wave and activation timing. Long-term success was achieved with focal ablation in the majority of patients.

The coronary sinus: Passive bystander or source of arrhythmia?1 1ASSOCIATE EDITOR: D. GEORGE WYSE

The coronary sinus provides access to the epicardial space of the heart allowing ablation of epicardial accessory pathways, foci of ventricular arrhythmia, and arrhythmogenic areas such as the vein or ligament of Marshall. In addition, its musculature may form atrioventricular accessory connections, participate in macroreentrant atrial arrhythmias, and generate foci of microreentrant atrial tachycardia and fibrillation. Thus, the coronary sinus may serve both as a bystander to arrhythmia circuits as well as an original source of cardiac arrhythmia.

A review of the coronary venous system: a road less travelled

Compared with the coronary arterial system, less attention has been paid to the coronary venous system. In the current era, there are therapeutic options for arrhythmias and for heart failure that use the coronary venous system to access target areas. We review the arrangement of the main cardiac veins to provide a morphologic background to interventionists. In general, the venous system is a useful conduit for delivery of percutaneous transcatheter treatment. But, variability in terms of valves, diameter, angulation, extent of muscular sleeves, proximity to other cardiac structures, and cross-over spatial relationship with branches of coronary arteries have implications for practitioners seeking to make use of the system.

Accessory pathway in left inferoposterior diverticulum masquerading as left posterior pathway due to conduction over coronary sinus to left atrium connection

We report the case of an accessory pathway in a left inferoposterior diverticulum. The pathway masqueraded as a true left lateral pathway due to the direction of activation over a coronary sinus to left atrium connection. The patient had undergone four prior failed ablation attempts at other institutions using both a transseptal and retrograde approach.

Coronary sinus-ventricular accessory connections producing posteroseptal and left posterior accessory pathways: incidence and electrophysiological identification

BACKGROUND

The coronary sinus (CS) has a myocardial coat (CSMC) with extensive connections to the left and right atria. We postulated that some posteroseptal and left posterior accessory pathways (CSAPs) result from connections between a cuff of CSMC extending along the middle cardiac vein (MCV) or posterior coronary vein (PCV) and the ventricle. The purpose of the present study was to use CS angiography and mapping to define and determine the incidence of CSAPs and determine the relationship to CS anatomy.

METHODS AND RESULTS

CSAP was defined by accessory pathway (AP) potential or earliest activation in the MCV or PCV and late activation at anular endocardial sites. A CSAP was identified in 171 of 480 patients undergoing ablation of a posteroseptal or left posterior AP. CS angiography revealed a CS diverticulum in 36 (21%) and fusiform or bulbous enlargement of the small cardiac vein, MCV, or CS in 15 (9%) patients. The remaining 120 (70%) patients had an angiographically normal CS. A CSMC extension potential (CSE), like an AP potential, was recorded in the MCV in 98 (82%), in the PCV in 13 (11%), in both the MCV and PCV in 6 (5%), and in the CS in 3 (2%) of 120 patients. CSMC potentials were recorded between the timing of atrial and CSE potentials.

CONCLUSIONS

CSAPs result from a connection between a CSMC extension (along the MCV or PCV) and the ventricle. The CS is angiographically normal in most patients.

Congenital malformations of the right atrium and the coronary sinus: an analysis based on 103 cases reported in the literature and two additional cases

STUDY OBJECTIVES

Congenital malformations of the right atrium (RA) and the coronary sinus (CS) are rare, and only sporadic cases have been reported. Little is known about the clinical relevance of this disorder. We report on two patients, one with a giant RA diverticulum, the other with a diverticulum of the CS, and review 103 cases of such malformations that have been reported previously.

DESIGN

A MEDLINE search was performed to collect all cases of congenital malformations of the RA and the CS reported in the literature between 1955 and 1998. Cases were classified into the following categories: (1) congenital enlargement of the RA; (2) single diverticulum of the RA; (3) multiple diverticula of the RA; and (4) diverticulum of the CS. Clinical presentation and outcome of the different types of malformations were analyzed.

RESULTS

The patients most frequently presenting with symptoms were those with diverticula of the CS (n = 28) followed by those with single diverticula of the RA (n = 13), multiple diverticula (n = 4), and congenital enlargements of the RA (n = 60). The percentages of symptomatic patients were 93, 84, 75, and 53%, respectively. Symptoms were frequently caused by arrhythmias. Supraventricular tachycardia (SVT) was found in 42 of the patients (40%) and was most common in patients with diverticula of the CS (24 of 28 patients) and multiple atrial diverticula (3 of 4 patients). Sudden cardiac death was reported more frequently in patients with diverticula of the CS (18%) compared to those with congenital enlargement of the RA (5%) or single or multiple diverticula of the RA (6%). All seven patients with diverticula of the CS who were not treated with catheter or surgical ablation eventually died.

CONCLUSION

Congenital malformations of the RA and the CS frequently are associated with arrhythmias. SVT and sudden cardiac death have been reported in a significant percentage of patients with diverticula of the CS.

Radiofrequency catheter ablation of a concealed atrioventricular accessory pathway associated with a coronary sinus diverticulum

A 31-year-old woman underwent radiofrequency catheter ablation of a concealed left posteroseptal accessory pathway associated with a coronary sinus diverticulum. The patient had previously undergone unsuccessful catheter ablation of the posteroseptal region of the mitral annulus. Coronary sinus venography revealed the presence of the diverticulum near the ostium. An electrogram in the neck of the diverticulum showed the shortest ventriculoatrial conduction time and a large accessory pathway potential during atrioventricular reciprocating tachycardia. The pathway was successfully ablated within the neck of the diverticulum. The findings in this case underscore the importance of coronary sinus venography before ablation.

A postmortem review of congenital cardiac malformations in a series of 180 adults, over the age of 16 years, born between 1865 and 1980

The evolution of diagnosis and treatment of congenital heart malformations can be traced through patients surviving into adulthood. We reviewed the heart specimens from 180 patients aged 16 to 86 years and considered the morphological features, the nature of any interventional procedures, and the events leading to death. Based on the mode of clinical presentation, 33 cases were considered covert, and the remaining 147 cases were known or suspected to have a cardiac abnormality during life. Of the symptomatic cases, 60 had no surgical intervention, whereas 167 surgical procedures had been performed in the remaining 87 cases. Acquired heart disease was noted in 7 of the covert cases and in 16 of the symptomatic cases. Overall, there were only 3 instances of errors in clinical identification of significant morphological abnormalities, and 2 cases related to surgical procedures. This review emphasizes the value of autopsy examination for clinicopathologic correlations and the case for retention of cardiac specimens for teaching purposes.

Electrical conduction between the right atrium and the left atrium via the musculature of the coronary sinus

BACKGROUND

The purpose of this study was to determine whether the coronary sinus (CS) musculature has electrical connections to the right atrium (RA) and left atrium (LA) and forms an RA-LA connection.

METHODS AND RESULTS

Six excised dog hearts were perfused in a Langendorff preparation. A 20-electrode catheter (2-4-2-mm spacing center to center) was placed along the CS. Excision of the pulmonary veins provided access to the LA, and a second 20-electrode catheter was placed along the LA endocardium opposite the CS catheter. An incision opened the CS longitudinally, and microelectrodes were inserted into the CS musculature and adjacent LA myocardium. Continuous CS musculature was visible along a 35+/-9-mm length of the CS beginning at the ostium. During lateral LA pacing, CS electrodes recorded double potentials, a rounded, low-frequency potential followed by a sharp potential. The rounded initial potential propagated in the lateral-to-septal direction and represented "far-field" LA activation (timing coincided with adjacent LA potentials and with action potentials recorded from microelectrodes in adjacent LA cells). The sharp potential represented CS activation (timing coincided with action potentials recorded from CS musculature). A distal LA-CS connection (earliest sharp potential in the CS during lateral LA pacing) was located 26+/-7 mm from the ostium. During RA pacing posterior to the CS ostium, CS electrodes recorded septal-to-lateral activation of the high-frequency potential, with slightly later activation of the rounded potential (LA activation). Incisions surrounding the CS ostium isolating the ostium from the RA had no effect on the CS musculature and LA potentials during RA pacing within the isolated segment containing the CS ostium. RA pacing outside the isolated segment delayed activation of the CS musculature until after LA activation, confirming that the RA-CS connection was located in the region of the CS ostium as well as confirming the presence of the LA-CS connection.

CONCLUSIONS

In canine hearts, the CS musculature is electrically connected to the RA and the LA and forms an RA-LA connection.

Development and validation of an ECG algorithm for identifying accessory pathway ablation site in Wolff-Parkinson-White syndrome

INTRODUCTION

Delta wave morphology correlates with the site of ventricular insertion of accessory AV pathways. Because lesions due to radiofrequency (RF) current are small and well defined, it may allow precise localization of accessory pathways. The purpose of this study was to use RF catheter ablation to develop an ECG algorithm to predict accessory pathway location.

METHODS AND RESULTS

An algorithm was developed by correlating a resting 12-lead ECG with the successful RF ablation site in 135 consecutive patients with a single, anterogradely conducting accessory pathway (Retrospective phase). This algorithm was subsequently tested prospectively in 121 consecutive patients (Prospective phase). The ECG findings included the initial 20 msec of the delta wave in leads I, II, aVF, and V1 [classified as positive (+), negative (-), or isoelectric (+/-)] and the ratio of R and S wave amplitudes in leads III and V1 (classified as R > or = S or R < S). When tested prospectively, the ECG algorithm accurately localized the accessory pathway to 1 of 10 sites around the tricuspid and mitral annuli or at subepicardial locations within the venous system of the heart. Overall sensitivity was 90% and specificity was 99%. The algorithm was particularly useful in correctly localizing anteroseptal (sensitivity 75%, specificity 99%), and mid-septal (sensitivity 100%, specificity 98%) accessory pathways as well as pathways requiring ablation from within ventricular venous branches or anomalies of the coronary sinus (sensitivity 100%, specificity 100%).

CONCLUSION

A simple ECG algorithm identifies accessory pathway ablation site in Wolff-Parkinson-White syndrome. A truly negative delta wave in lead II predicts ablation within the coronary venous system.

Anatomy of the atrioventricular junctions with regard to ventricular preexcitation

In the normal heart, the atrioventricular junctions surround the orifices of the mitral and tricuspid valves. The septal area of the junctions is much smaller than generally thought, being made up of the fibrous membranous septum and the muscular atrioventricular septum. The left atrioventricular junction gives the potential for muscular atrioventricular contiguities only in relation to the mural leaflet of the mitral valve. The right junction extends from the area posterior to the muscular atrioventricular septum to the supraventricular crest of the right ventricle. Anomalous pathways for conduction, which produce pre-excitation, can be found anywhere within these atrioventricular junctions. The pathways usually are the muscular accessory connections responsible for the Wolff-Parkinson-White syndrome, which can exist in the left, septal, or right junctions. Specific muscular connections are found in the presence of Purkinje cell tumors, diverticulums of the coronary sinus, or when taking origin from nodes of Kent at the acute margin of the ventricular mass. The latter connections are responsible for most examples of so-called Mahaim conduction, and are also described as atriofascicular tracts. The true Mahaim fibers are best described as nodoventricular or fasciculo-ventricular connections, while the pathway previously labelled as atriofascicular by the European Study Group is now best distinguished as an atrio-Hisian tract. The slow and fast pathways into the atrioventricular node are composed or ordinary atrial myocardium, the orientation of the fibers probably producing preferential conduction.

Echocardiographic demonstration of coronary sinus diverticula in patients with Wolff-Parkinson-White syndrome

Coronary sinus (CS) diverticula have been reported to be the anatomic basis of some posteroseptal accessory atrioventricular pathways. During 1 year, 53 patients with Wolff-Parkinson-White syndrome referred to our center for catheter ablation were found to have posteroseptal or left posterior accessory pathways. The accessory pathway was associated with an anomaly of the CS in seven patients (13%), including six diverticula of the CS or its branches and one aneurysmal CS. Four of the CS diverticula were visualized by transesophageal echocardiography. Diverticular appear as echolucent, contractile pouches on the epicardial surface of the posteroseptal or posterior left ventricle that connect to the CS by an isthmus. Previous reports have suggested that accessory pathways associated with CS aneurysms have rapid conduction times and may be associated with an increased risk of rapid ventricular response during atrial fibrillation and sudden death; five of our seven patients had a short preexcited R-R interval in the range of 172 to 225 msec during atrial fibrillation. In summary, many, if not the majority, of CS diverticula associated with preexcitation can be visualized by transesophageal echocardiography.

Prospective study of retrograde coronary venography in patients with posteroseptal and left-sided accessory atrioventricular pathways

The morphologic features of the coronary vein system was prospectively studied with retrograde venography in 117 patients with left-sided (78 patients) and posteroseptal accessory pathway (39). Findings were compared with accessory pathway localization. A mean of 3.3 +/- 1.5 venous branches draining into the coronary sinus or the great cardiac vein could be visualized. The morphologic condition was described and classified. Incidence, morphologic condition, and distribution did not differ between left-sided and posteroseptal accessory pathway. Venous abnormalities including ectasy, diverticulum, narrowing, angulation, and hypoplasia occurred in 22.2%. Diverticulum and narrowing were present in posteroseptal accessory pathway only and always related to the successful ablation site. In patients with left-sided accessory pathway, ectasy, angulation, and hypoplasia were found. Anomalies were less frequent (9% vs 43.6%, p < 0.001) and had no relation to accessory pathway localization. However, the successful ablation site was in 42.3% located < 5 mm to an angiographically visualized venous branch. In conclusion, posteroseptal accessory pathways are often related to coronary sinus abnormalities. In patients with a left-sided accessory pathway venous malformation is uncommon, whereas a close anatomic relation exists between accessory pathway localization and venous ventricular branches.

Echocardiographic imaging of coronary sinus diverticula and middle cardiac veins in patients with preexcitation syndrome: impact on radiofrequency catheter ablation of posteroseptal accessory pathways

To determine the value of echocardiography for identifying coronary sinus (CS) diverticula and middle cardiac veins (MCVs) in patients with posteroseptal accessory pathways (PAPs), transthoracic (TTE) and transesophageal echocardiography (TEE) were performed in 18 consecutive patients with PAP and in 15 control subjects with left lateral accessory pathway before CS angiography. The size, shape, and location of CS diverticula and MCV were described and compared to angiography. TEE and angiography were concordant for the identification of diverticula (n = 5) and agreed for depicting MCV in 22 of the 27 cases. TTE revealed 4 of 5 diverticula and identified 4 of 27 MCV (P < 0.001). Fourteen MCV but no diverticula were found in the control subject. There was no significant difference between transesophageal and angiographic measurements for the width (23.5 +/- 4.9 vs 26.8 +/- 6.6 mm) and height (13.5 +/- 3.8 vs 15.7 +/- 3.4 mm) of the diverticula, and the width (3.5 +/- 0.7 vs 3.7 +/- 0.6 mm) of MCV. TEE underestimated the length of the MCV (12.0 +/- 1.8 vs 27.2 +/- 6.0, P < 0.001). Delivery of radiofrequency energy within the neck of a diverticulum or within an MCV was successful in 5 of 5, and 6 of 13 cases in patients with PAPs, respectively. In conclusion, echocardiography was as reliable as angiography for detecting and describing CS diverticula and MCV in patients with preexcitation syndrome. Echocardiography is recommended prior to electrophysiological study because it may simplify radiofrequency catheter ablation.

Posteroseptal accessory pathways: an overview of anatomical characteristics, electrocardiographic patterns, electrophysiological features, and ablative therapy

First, the posteroseptal region of the heart is probably the most complex area among those that harbor AV accessory fibers and a firm grasp of the anatomical characteristics of this region may facilitate achieving a successful AP ablation. Second, there is no sharp demarcation between the posteroseptal area and its surrounding regions including mid-septal, left posterior paraseptal, and right posterior paraseptal locations. Therefore, there are some inevitable overlaps between the electrocardiographic and electrophysiological features of APs located in the posteroseptal region and those areas immediately adjacent to it. Third, in the vast majority of cases, successful ablation can be achieved using a right atrial approach. Therefore, dividing posteroseptal APs into right- or left-sided pathways may only be useful for describing their ECG or electrophysiological characteristics with little or no value in predicting the site of successful ablation. Fourth, it seems advisable to attempt efforts to induce functional bundle branch block during orthodromic tachycardia and assess its effect on the VA interval. Ventriculoatrial interval prolongation due to right bundle branch block strongly favors a right free-wall or anteroseptal AP location. Prolongation of the VA interval by 30 msec or less in response to left bundle branch block is compatible with a posteroseptal location. In this situation, the mapping and ablative efforts should primarily be focused on the right atrial approach, including the terminal coronary sinus. If left bundle branch block causes VA interval lengthening of 30 msec or greater, the AP is most likely in the left free-wall region, including the posterior paraseptal area. Finally, the presence of APs having an intimate relationship with the middle cardiac (posterior interventricular) vein or the coronary sinus pouch, although exceedingly uncommon, should be considered in difficult cases in which radiofrequency applications to the conventional posteroseptal locations are unsuccessful. Such cases may require coronary sinus venography for better visualization and precise mapping of the terminal sinus complex.

Safety of radiofrequency catheter ablation of accessory atrioventricular pathways

The acute anatomic and valvular consequences of radiofrequency catheter ablation of accessory pathways were evaluated in 62 patients by means of serial echocardiographic examinations. Semiquantitative assessment of valvular incompetence and classification into one of four grades according to the width and the extension of the jet from the valvular orifice were carried out. Segmental wall motion abnormalities were evaluated semiquantitatively with four grades of severity (normal, hypokinesia, akinesia, or dyskinesia). New echocardiographic abnormalities were observed in five patients. One thrombus on the ventricular aspect of the mitral valve, three hemodynamically insignificant pericardial effusions, and one increase in severity of tricuspid incompetence were found 1 day after radiofrequency catheter ablation. We conclude that echocardiographic changes after radiofrequency ablation of accessory pathways are rare and of minor significance. These findings confirm the safety of the procedure.

Surgical anatomy of accessory connections of atrioventricular conduction

Forty-nine descriptions of accessory pathways of atrioventricular (AV) conduction have been analyzed in the search for reasons for an occasional failure of interruption by operation. The validity of the steps now used for open interruption of connections was confirmed. Several possible but highly speculative reasons were found for failure. A pathway might remain intact after operation because atrial muscle on the AV valve may act as a pathway route after an atriotomy made just above the annulus. In another situation, the AV valve myocardium might be continuous with a papillary muscle directly attached to the valve. The small, middle, and great coronary veins, when budding from the coronary sinus, might carry with them an AV connection that escaped the invasion of the primitive AV junction by sulcus tissue. Final proof of these conjectures awaits more studies of hearts with accessory pathways of AV conduction.

A posteroseptal accessory pathway located in a coronary sinus aneurysm: diagnosis and radiofrequency catheter ablation

A coronary sinus aneurysm was diagnosed by means of echocardiography, coronary sinus contrast angiography, coronary angiography, and nuclear magnetic resonance imaging in a patient with Wolff-Parkinson-White syndrome caused by a posteroseptal accessory pathway. Percutaneous radiofrequency current catheter ablation performed in the isthmus of the coronary sinus aneurysm was successful.

Giant right atrial diverticulum: an unusual cause of Wolff-Parkinson-White syndrome

A case of a giant right atrial diverticulum associated with neonatal supraventricular tachycardia is reported. The electrocardiogram in sinus rhythm showed pre-excitation that may have been caused by the right atrial diverticulum adhering to the right ventricle.

Radiofrequency catheter ablation for Wolff-Parkinson-White syndrome associated with a coronary sinus diverticulum

The case of a patient with Wolff-Parkinson-White syndrome undergoing attempted radiofrequency catheter ablation of a left posterior paraseptal accessory pathway is described. Coronary sinus venography revealed the presence of a large diverticulum attaching near the os. The electrogram recorded from a catheter placed in the narrow neck of the diverticulum revealed a very short atrioventricular time during sinus rhythm. The pathway was easily ablated using radiofrequency energy applied in the neck of the diverticulum, after multiple failed attempts at catheter ablation from the endocardial surface of the mitral annulus. Our report emphasizes the importance of searching for a coronary sinus diverticulum in all patients with posterior accessory pathways undergoing catheter ablation.

Low energy catheter ablation of a posteroseptal accessory pathway associated with a diverticulum of the coronary sinus

A 23-year-old man was resuscitated from ventricular fibrillation and subsequently shown to have the Wolff-Parkinson-White syndrome. Electrophysiological study demonstrated a posteroseptal accessory pathway, and coronary sinus angiography demonstrated that this was associated with a diverticulum of the coronary sinus. Catheter ablation was performed using a new low energy system. Five shocks were delivered within the coronary sinus diverticulum, with a cumulative energy of 39 joules (J). Accessory pathway conduction was blocked successfully, and there were no complications.

Surgical division of posterior septal accessory pathways in the Wolff-Parkinson-White syndrome: a new modified approach

A new modified surgical approach for the division of posterior septal accessory pathways is described. This method incorporates some of the desirable components of previously reported techniques, while eliminating difficult and unreliable aspects of those same techniques. Interestingly this procedure was initially illustrated by Sealy and Mikat in 1983, although it has not been used clinically until now. The recognized intent of this dissection is to totally separate atrial and ventricular structures within the posterior septal space so that all accessory pathways encountered are permanently interrupted.

Wolff-Parkinson-White syndrome associated with a coronary sinus diverticulum: ablative surgical approach

This report concerns a patient with drug refractory supraventricular tachycardia due to the Wolff-Parkinson-White syndrome in association with a coronary sinus diverticulum. Division of the anomalous bypass tract was initially performed by an endocardial approach together with circumferential dissection of the neck of the diverticulum. This procedure failed to ablate the bypass tract that was only successfully divided when the superficial wall of the diverticulum was excised. This case illustrates the close association that exists between an anomalous atrioventricular bypass tract and a coronary sinus diverticulum, and the importance of dividing the superficial wall of the diverticulum as an integral part of the ablative procedure.