Introduction: Dextrocardia is a rare congenital heart disease, potentially associated with intracardiac defects and vascular malformations. Permanent pacemaker (PM) implantation in patients with dextrocardia and vascular malformations, such as persistent right superior vena cava (PRSVC), can pose significant technical challenges, requiring an individually tailored approach.
Case presentation: An 53 year-old woman, with a known diagnosis of situs inversus dextrocardia, who was admitted for fatigue. Her cardiovascular physical examination was remarkable for a right sided point of maximal impulse, an irregular cardiac rhythm and a heart rate of 40 bpm. On admission, her standard 12-lead ECG showed sinus bradycardia and junctional es-cape beats with a negative P wave in lead I; the QRS complex was narrow, with right axis deviation and no R-wave progression in the precordial leads, consistent with dextrocardia. Placing the electrodes in a „mirror-image” position resulted in a normal ECG, except for the sinus dysfunction findings. Holter monitoring re-vealed sinus bradycardia, with an average heart rate of 55 bpm, alternating with junctional rhythm. She was not on any antiarrhythmic drugs and had no other reversible cause for bradycardia. Thus, the diagnosis of symptomatic sinus node disease was established, with an indication for PM implantation. Echocardiography was performed from a right lateral decubitus position and the images were obtained from “mirrored” classic acoustic windows. The examination was within normal limits, with the exception of an enlarged coronary sinus, visible on both modified apical four-chamber view and apical two-chamber view. Venography was used to evaluate the superior caval system. Injection of contrast in a right antecubital vein revealed drainage of the right subclavian vein into the coronary sinus via a PRSVC, while injection in the contralateral venous system showed proper drainage of the left subclavian vein into the right atrium via a left superior vena cava. The permanent pacemaker implantation procedure was performed from the left side. The left cephalic vein was used to insert a bipolar active fixation lead into the right atrial appendage, via the left superior vena cava. The lead was connected to a single-chamber pacemaker, programmed AAIR 60. The post-procedural course was uneventful.
Discussion: Situs inversus dextrocardia is a rare fin-ding, occurring in about 0.01% of the population. It can be associated with anomalous central venous drainage, which should be considered in the advent of transveno-us PM implantation. In our patient, the suspicion of an anomalous superior vena cava was raised during echocardiography, which identified an enlarged coronary si-nus, and then confirmed by venography. Knowledge of the anatomy aided in planning a successful PM implant procedure. The left venous system was used for implantation, rather than the right anomalous venous course.
Conclusion: Pacemaker implantation in patients with dextrocardia can be technically challenging because of the distorted anatomy, and can be further complicated by venous malformations, such as PRSVC. Active pre-procedural echocardiographic and venographic screening for an abnormal venous drainage can help the implanting physician establish the safest approach.