Endocardial silicone lead wear: description of tribological phenomena on the basis of microscopic examination of removed leads. Preliminary report.

BACKGROUND: The passage of a lead in tissues and in the cardiovascular system depends on the implantation technique. The structure of the leads, which is a combination of two or more materials, triggers their wear. Breakage of the external pacemaker (PM) lead insulation causes unsealing of the lead and exposure of its internal spaces, which can be the anchor of lead-dependent infective endocarditis (LDIE). In the case of implantable cardioverter-defibrillator (ICD) leads, damage to external insulation isthe cause of externalisation of the cable. AIM: To describe endocardial lead abrasion as a tribological phenomenon resulting from rubbing the leads against each other in the mechanism of polymer on polymer friction, and other mechanisms associated with lead structure i.e. polymer on metal friction. METHODS: Twenty-two leads were extracted from ten patients (three women) aged 66.5 ± 13.4 years. In all cases, the reason for lead removal was infection ­ in 80% LDIE. The PM (one ICD) two- and three-lead systems, all with silicone insulation, were aged 3­25, mean 8.3 years. The destroyed polymer insulation was examined by optical and scanning electron microscopy. The site of damage was defined as the length of the lead from its distal end. This lead segment motion was analysed on chest scopy performed prior to the removal procedure. In this way, three sites of lead damage were distinguished: intracardiac, intravenous, and intrapocket. Tribological wear was observed on the polymer-metal interface and between the leads. The following characteristics were recorded: the type of PM or ICD system in which the extracted leads worked, the lead dwell time,and the lead model. RESULTS: Scanning electron examinations showed that in all cases lead insulation had undergone tribological failure. In all samples, the image of fatigue wear was recorded. In all examined places, we found evidence that adhesive wear was present with the transfer of material to the edges of friction zones and/or to friction partners. In 80% of the patients with LDIE, a total breakage of insulation and abrasive wear was observed, especially when a lead cyclically bent and rubbed against another lead. Abrasive wear was the cause of lead unsealing at sites of strong lead bending, in the right atrium near the tricuspid valve. CONCLUSIONS: Acknowledging the tribological mechanism may connect the commonly known crush syndrome with lead abrasion in the cardiac implantable device pocket and in the heart cavity.

[Change of quality of life and NYHA class in patients with advanced heart failure and permanent atrial fibrillation after 12-months period from upgrade of pacing system]. / Zmiana jakosci zycia oraz klasyfikacji NYHA u chorych z zaawansowana niewydolnoscia serca i utrwalonym migotaniem przedsionków po 12 miesiacach od rozbudowy systemu stymulacji.

UNLABELLED: There is no research on the change of quality of life and NYHA classification after pacing system upgrade performed as a treatment of advanced heart failure during a long observation period in a particular population of patients with long-term apical right ventricular pacing, permanent atrial fibrillation and complete atrio-ventricular block. The aim of the study was evaluation of changes in quality of life and NYHA class in group of patients in which upgrade from right ventricular apical pacing to biventricular or bifocal right ventricular pacing was done. MATERIAL AND METHODS: Evaluation of quality of life was performed in a chosen group of 27 patients (20 males, mean age 71.2) who completed the 12-month observation period. Quality of life was assessed by the Short Form-36 (SF-36) questionnaire. The first examination was carried out before the planned pacing system upgrade, that is, when advanced heart failure appeared in the course of permanent atrial fibrillation and right ventricular apical pacing present for a long time (on average 7.7 years). The change of quality of life after 12-month period of upgrade pacing system was analyzed. A comparison of patient's self assessment (as far as physical aspect of quality of life is concerned - Physical Component Summary - PCS) with doctor's interview concerning NYHA classification was performed. Additionally quality of life pointed out by a patient was analyzed in relation to the diseases most common in this population: hypertension, diabetes mellitus and renal failure. Because the questionnaires were completed by the patients personally without the third party, the assessment referred to mistakes in filling in the questionnaires (quantity of missed questions and incorrect marking the answers by adding individual comments) in relation to patients' age. RESULTS: In 12-month follow-up after pacing system upgrade, improvement of quality of life was found in 48.1% of patients. Assessment of physical aspect of quality of life was possible due to SF-36. Improvement occurred in 55.5% of patients, however in relation with NYHA classification improvement appeared in 51.8% of patients. Improvement in NYHA was in significant correlation with improvement in physical aspect of life (p = 0.025), especially in the subgroup treated by pacing system upgrade to bifocal right ventricular pacing (p = 0.0066). In the subgroup with improvement, hypertension and diabetes were less frequent, however frequency of renal failure was greater, than in the subgroup without quality of live improvement. Both before and after pacing system upgrade, there was no significant connection (only a trend) between the number of mistakes done during self-completion of the questionnaires and patients' age. CONCLUSIONS: In 12-month follow-up after pacing system upgrade, improvement of quality of life was found in 48.1% of patients. There exists a significant correlation between the improvement of physical efficiency in NYHA class and the improvement in physical aspect of quality of life in patients' self assessment (p = 0.025). In the subgroup treated by pacing system upgrade to bifocal right ventricular pacing this correlation is especially strong (p = 0.0066).