Left bundle branch block tachycardia in a case of dextrocardia: What is the mechanism?

摘要

A 51-year-old man with a history of dextrocardia with situs solitus, D-loop ventricles, and normally related great arteries was referred to our center because of recurrent episodes of regular palpitations, with a sudden onset and offset. His past medical history was remarkable for a surgical intervention of correction of partial anomalous pulmonary venous return (consisting in a scimitar vein draining the superior and medial lobes of the right lung and emptying into the junction between the inferior vena cava and the right atrium) and of an ostium secundum atrial septal defect. Furthermore, the patient was known for intermittent preexci-tation and had already undergone an electrophysiological study and radiofrequency ablation of the slow pathway after evidence of an atypical (fast/slow) atrioventricular nodal tachycardia in another center. A new electrophysiological study was planned. Baseline ECG confirmed the presence of intermittent preexcitation. Cannulation of the coronary sinus (CS) was not possible due to anatomical issues.