Single and dual chamber pacemaker implantationin patients with left superior vena cava persistence –own experiences

Persistent left superior vena cava (LSVC) is a rare syndrome occurring in ca. 0.3% of the population without congenital heart defects. Most frequently this syndrome has no symptoms and is discovered incidentally during the autopsy or pacemaker or cardioverter-defibrillator implantation trials [1–3]. Ninety-two percent of cases show that the persistent left superior vena cava passes to the enlarging coronary sinus and subsequently to the right atrium. Left superior vena cava is observed in about 10% of the population with congenital heart defects, in which 0.07–0.13% of the LSVC cases are accompanied by atresia of the proper right superior vena cava [4, 5]. The aforementioned cases show that LSVC is the only blood vessel which pumps out blood from the upper part of the body and may result in severe technical problems as well as the vena cava superior syndrome [1–4, 6–8]. According to the relevant literature, the anomalies described herein are frequently accompanied by arrhythmic disorders, e.g. short PQ, syndrome of malfunctioning sinus node, ectopic atrial rhythms, total atrioventricular block and tachyarrhythmia [7]. Presence of the LSVC is a direct result of improper venous system development in the early stage of embryo evolution. In the first weeks of life the two anterior essential veins conduct part of the cranial blood. Analogically, two posterior essential veins conduct blood from the lower body parts. At the end of the second month of the embryo’s life, after enablement of sinus venosus to the right atrium, both anterior essential veins form an anastomosis, which then transforms into the left brachiocephalic vein. Disappearance of the left anterior essential vein below the anastomosis may be observed at a later stage. Furthermore, the section above transforms into the left internal jugular vein. The right anterior essential vein is preserved entirely and its frontal section forms the analogical right internal jugular vein. The section below the right subclavian vein estuary transforms into the right brachiocephalic vein. Similarly, the section below the left brachiocephalic vein transforms into the LSVC [6–10].