Successful ablation of a left-sided accessory pathway in a patient with coronary sinus atresia and arteriovenous fistula: clinical and developmental insights

Abstract

Background and objectives: While radiofrequency ablation catheter ablation of accessory pathways is generally safe and effective, anatomic variants can cause considerable challenges in effecting cure. Our objective was to use an unusual case where coronary sinus was absent and arterial venous fistula was present and a left-sided pathway required mapping and ablation to develop a framework to approach difficult cases.

Method: A detailed literature search and review of contemporary cardiac embryology was undertaken to attempt and to explain a common developmental anomaly. Adjunctive approaches during the ablation procedure, including intracardiac ultrasound, were used to guide mapping and ablation despite the lack of coronary sinus access.

Results: The accessory pathway was successfully ablated using a transseptal approach and intracardiac ultrasound guided mapping of the mitral annulus. A potential common mechanism to explain the apparently disparate anatomic variants in this patient was formulated.

Conclusions: Cardiac conduction development is complex and accessory pathway conduction may occur in the setting of arteriovenous anomalies thus providing insights as to the cause of WPW syndrome. Successful mapping and targeted ablation of left-sided pathways may be accomplished even when coronary sinus access is not possible.

Keywords: Coronary sinus; accessory pathway; coronary AV fistula; coronary atresia; epicardially-derived cells.

Figure 1

Electrocardiograms at baseline (panel A) and postablation. Baseline ECG shows manifest preexcitation with suggestion of a right-sided pathway (positive delta wave in lead I, S wave larger than R wave in lead V1). Panel B shows absence of preexcitation following ablation in the left posterior region (see text for details).

Figure 1

Electrocardiograms at baseline (panel A) and postablation. Baseline ECG shows manifest preexcitation with suggestion of a right-sided pathway (positive delta wave in lead I, S wave larger than R wave in lead V1). Panel B shows absence of preexcitation following ablation in the left posterior region (see text for details).

Figure 2

Magnified CT scan image showing coronary sinus ostial atresia. The CS is seen to taper abruptly and end approximate 3.4 mm before reaching the right atrium (see figure 3 for comparison). Abbreviations: RA = right atrium, LV = left ventricle, IVC = inferior vena cava

Figure 3

The normal emptying of the coronary sinus into the right atrium is shown for comparison with the abnormality found in this patient (figure 2). RV = right ventricle; AO = aorta, ES = Eustachian Ridge. RA = right atrium, LV = left ventricle, IVC = inferior vena cava

Figure 4

Three-dimensional reconstruction of the posterior and left posterolateral surface of the heart showing the markedly enlarged great cardiac vein and middle cardiac vein in tehis patient with coronary atresia. The thin yellow arrow points to the site of coronary arteriovenous connection between the posterior descending artery and the mid portion of the middle cardiac vein. Note the abrupt enlargement of the middle cardiac vein proximal to this malformation.

Figure 5

Schematic outline of cardiac embryogenesis. The importance of the epicardially derived cells in conduction system, septation, annulus development, as well as vascular development is described in the text.