[Parameters of cardiac pacing and effectiveness of defibrillation during implantable cardioverter-defibrillator lead implantation to right ventricle outflow tract].

UNLABELLED: Traditional implantation site for implantable cardioverter-defibrillator (ICD) is right ventricular apex (RVA). According to many data, this location ensures low enough defibrillation threshold. ICDs are more often implanted in patients with impaired left ventricle function, in whom, along with disease progression, the need for permanent stimulation develops. Right ventricle outflow tract (RVOT) is considered to be a better site for permanent stimulation. The aim of the study was to assess acute parameters of an ICD lead implantation to RVOT. These are: electrical parameters measured during implantation, defibrillation safety margin (DSM) and some acute complications requiring reoperation. MATERIAL AND METHODS: The study was retrospective. 113 consecutive patients were included in the study (including 19 women, mean age was 60,08 years), who had a single coil ICD lead implanted in the clinic from 2008 to 2012. The implantation site was left to the physicians' discretion, which resulted in majority of RVOT implantations. Among indications to implantation in both groups ischaemic cardiomiopathy with low ejection fraction was a main indication. Excluding criteria were: using dual coil lead, lack of DSM, device of resynchronization implantation. During implantation procedure the following parameters were assessed: R wave amplitude, lead impedance, ventricular pacing threshold. DSM was performed according to the attached scheme. Analysis included: implantation criteria (primary or secondary prevention), demographic and clinical factors, administered anti-arrhythmic medications. RESULTS: In 91 patients (80.53% of the population) the lead was primarily positioned in RVOT while in 22 patients (19.47%) in RVA. In the primarily RVOT group, 50% of ICDs were dual chamber, while in RVA group it was 36%. There were no statistically significant differences between the groups in relation to pacing threshold, lead impedance or R wave amplitude. In 20 patients the lead was repositioned from RVOT to RVA and in 3 from RVA to RVOT due to inappropriate pacing parameters. DSM was satisfying in all of the patients. However, in patients implanted in primary prevention 20% of leads needed repositioning. In patients implanted in secondary prevention 25% of leads needed repositioning. Due to small patient groups, statistical calculations were not feasible in this matter. Complications demanding reoperation were the following: 1 case of right ventricle perforation, 2 cases of atrial lead dislodgement, 3 pocket haematomas, 1 ventricular exit block and 1 infection. CONCLUSIONS: Acute ventricular pacing parameters of single coil defibrillator leads do not differ significantly between RVA and RVOT. Surgical complications in both groups are similar, while permanent RVOT stimulation seems to be clinically better. Further observation in order to determine long term consequences of implantation in different sites seems reasonable.