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Complications of permanent cardiac pacing in patients with persistent left superior vena cava.

BACKGROUND
Persistent left superior vena cava (PLSVC) is present in about 0.3-0.5% of the general population and in about 12% of patients with other abnormalities. This congenital anomaly is usually asymptomatic and does not cause any physiological problems. However, it may become a significant problem in multiple clinical situations. Various complications related to PLVSC are encountered in anesthesiological, nephrological, oncological and cardiological procedures. The presence of PLSVC is usually incidentally detected during placement of pacemaker (PM), implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy (CRT) leads. Technical difficulties during lead positioning (especially ventricular leads) are commonly known and often described in the literature. The purpose of the present study was to evaluate the specific methods used for implantation of increasingly complicated pacing systems, finding an optimal strategy in patients with PLSVC, especially with electrotherapy complications.


METHODS
We performed a single-center retrospective analysis of 11 patients (7 women and 4 men, mean age 60.4 ± 13 years) with PLSVC hospitalized in single Cardiology Department between 2000 and 2012. The clinical characteristic, indications for PM/ICD/CRT implantation, technique of implantation and complications were evaluated.


RESULTS
In PLSVC patients, different indications for pacing or resynchronization therapy were represented: sick sinus syndrome (SSS) in 4 patients, 3rd degree atrio-ventricular (AV) block in 4 patients, dilated cardiomyopathy with left bundle branch block in 2 patients, dilated cardiomyopathy and non-sustained ventricular tachycardia episodes in 1 patient. In patients no. 1, 3, 4 and 10 the complications necessitated the change of leads or type of pacing. Transvenous lead extraction was successfully performed in patient no. 1 and 10 with re-implantation of new leads via PLSVC in patient no. 1 and via right superior vena cava in patient no. 10. Patient no. 3 received an additional ventricular lead via PLSVC because of 2nd degree AV block (formerly atrial lead implanted due to SSS). In patient no. 4 with left atrial pacing (lead in coronary sinus), prosthetic mitral valve replacement was combined with epicardial ventricular lead placement. Patients no. 2 and 7 received a CRT device, without technical problems in patient no. 7, whereas in patient no. 2 due to difficulties with left ventricular lead positioning a hybrid approach to epicardial lead pacing was used. In patient no. 8 an ICD was implanted with difficulty in placing defibrillator lead. Patient no. 5 received 2 atrial leads via PLSVC with successful biatrial pacing; patient no. 6 with the necessity of DDD pacing had a (ventricular) lead for left atrial pacing and a typical right ventricular lead. In patients no. 9 and 11 typical DDD pacing was used with contralateral placement of the leads due to anatomical and technical differences. After 12 years of follow-up the survival is 90.9%. Late electrotherapy complications have developed only in patient no. 8 (problems with the defibrillator lead).


CONCLUSIONS
Patients with PLSVC are a very heterogeneous group with different indications for pacing, therefore individualization of therapy is required. Technical complications connected with pacing of the right heart chambers are commonly known, hence transvenous left atrial or left ventricular lead implantation should be attempted. In case of difficulties in transvenous positioning of the lead, a hybrid or isolated cardiac surgery technique should be considered. Because of the increasing number of electrotherapy complications, these problems are also present in PLSVC patients. Transvenous lead extraction with re-implantation of a pacing system has not been reported yet. For this reason a thorough evaluation of the venous system is required in PLSVC patients before intervention.