Michał Lewandowski

Subacute cardiac perforations associated with active fixation leads

AIMS Having several recently published reports on increased rate of cardiac perforation with some lead models as background, we assess the relation between cardiac perforations and models of leads used. METHODS AND RESULTS All pacing and defibrillation leads implantations between 1 January 2007 and 31 March 2008 were analysed retrospectively. There were 2247 leads implanted in 1419 patients aged 67.6 +/- 14.1, 1200 (53%) active and 1047 (47%) passive fixation leads. Cardiac perforation occurred in eight patients (0.5%). The number of perforations does not differ significantly between the pacemaker and implantable cardioverter defibrillator implantations (five and three cases, respectively, P = 0.13). All perforations were associated with the active fixation leads implantation (8 vs. 0, P < 0.01). Only four models of leads were associated with perforations, but the risk of their use was not statistically significantly increased, when compared with other active fixation leads placed in the adequate position. CONCLUSIONS The incidence of cardiac perforation related to pacing and defibrillation leads is low. The use of active fixation leads is associated with an increased risk of cardiac perforation. We did not find any correlation between the perforation rate and any particular model of the implanted lead.

Long-term follow-up of children and young adults treated with implantable cardioverter-defibrillator: the authors' own experience with optimal implantable cardioverter-defibrillator programming.

AIMS Young implantable cardioverter-defibrillator (ICD) recipients present a high rate of inappropriate interventions. Some of them are caused by suboptimal pre-discharge programming of the device. There are conflicting data as regards antitachycardia pacing (ATP) effectiveness in children and young adults. We report our experience with ICD programming and a rate of complications during a 10 year follow-up. METHODS AND RESULTS We analysed the use and effectiveness of ATP and complications rate in 63 patients aged 6-21 years. Antitachycardia pacing (burst or ramp) was programmed ON in 14 patients (22%), 49 patients (78%) had only ventricular fibrillation (VF) therapy when discharged after implantation. The incidence of effective vs. ineffective or harmful ATP therapy: 5% of patients vs. 19% of patients differed significantly (P < 0.05). Fourteen patients (22%) received > or =1 appropriate shock(s) for ventricular tachycardia/VF and 17 patients (27%) had one or multiple inappropriate therapy (IT). Inappropriate therapy resulted from T-wave over-sensing (nine patients), sinus tachycardia (three patients), fast atrial fibrillation (five patients), and lead insulation disruption (1%). Reprogramming of the device eliminated IT in all cases. There were 13 (21%) surgical complications. Serious psychological sequelae developed in 27 (43%) patients. There was one death during the follow-up period. CONCLUSION Antitachycardia pacing therapy is rarely effective and often harmful in young ICD recipients. In most patients, programming ICD for only VF therapy is sufficient. Routine pre-discharge programming against inappropriate interventions (especially T-wave over-sensing) helps to reduce the incidence of discharges during the follow-up. The incidence of complications and inappropriate therapies is high in young ICD recipients and affects 50% of patients.

Fuzzy logic-based diagnostic algorithm for implantable cardioverter defibrillators

OBJECTIVE The paper presents a diagnostic algorithm for classifying cardiac tachyarrhythmias for implantable cardioverter defibrillators (ICDs). The main aim was to develop an algorithm that could reduce the rate of occurrence of inappropriate therapies, which are often observed in existing ICDs. To achieve low energy consumption, which is a critical factor for implantable medical devices, very low computational complexity of the algorithm was crucial. The study describes and validates such an algorithm and estimates its clinical value. METHODOLOGY The algorithm was based on the heart rate variability (HRV) analysis. The input data for our algorithm were: RR-interval (I), as extracted from raw intracardiac electrogram (EGM), and in addition two other features of HRV called here onset (ONS) and instability (INST). 6 diagnostic categories were considered: ventricular fibrillation (VF), ventricular tachycardia (VT), sinus tachycardia (ST), detection artifacts and irregularities (including extrasystoles) (DAI), atrial tachyarrhythmias (ATF) and no tachycardia (i.e. normal sinus rhythm) (NT). The initial set of fuzzy rules based on the distributions of I, ONS and INST in the 6 categories was optimized by means of a software tool for automatic rule assessment using simulated annealing. A training data set with 74 EGM recordings was used during optimization, and the algorithm was validated with a validation data set with 58 EGM recordings. Real life recordings stored in defibrillator memories were used. Additionally the algorithm was tested on 2 sets of recordings from the PhysioBank databases: MIT-BIH Arrhythmia Database and MIT-BIH Supraventricular Arrhythmia Database. A custom CMOS integrated circuit implementing the diagnostic algorithm was designed in order to estimate the power consumption. A dedicated Web site, which provides public online access to the algorithm, has been created and is available for testing it. RESULTS The total number of events in our training and validation sets was 132. In total 57 shocks and 28 antitachycardia pacing (ATP) therapies were delivered by ICDs. 25 out of 57 shocks were unjustified: 7 for ST, 12 for DAI, 6 for ATF. Our fuzzy rule-based diagnostic algorithm correctly recognized all episodes of VF and VT, except for one case where VT was recognized as VF. In four cases short lasting, spontaneously ending VT episodes were not detected (in these cases no therapy was needed and they were not detected by ICDs either). In other words, a fuzzy logic algorithm driven ICD would deliver one unjustified shock and deliver correct therapies in all other cases. In the tests, no adjustments of our algorithm to individual patients were needed. The sensitivity and specificity calculated from the results were 100% and 98%, respectively. In 126 ECG recordings from PhysioBank (about 30min each) our algorithm incorrectly detected 4 episodes of VT, which should rather be classified as fast supraventricular tachycardias. The estimated power consumption of the dedicated integrated circuit implementing the algorithm was below 120nW. CONCLUSION The paper presents a fuzzy logic-based control algorithm for ICD. Its main advantages are: simplicity and ability to decrease the rate of occurrence of inappropriate therapies. The algorithm can work in real time (i.e. update the diagnosis after every RR-interval) with very limited computational resources.

Reduction of the inappropriate ICD therapies by implementing a new fuzzy logic-based diagnostic algorithm.

The aim of the study was to analyze the value of a completely new fuzzy logic–based detection algorithm (FA) in comparison with arrhythmia classification algorithms used in existing ICDs in order to demonstrate whether the rate of inappropriate therapies can be reduced.

Fifteen years’ experience of implantable cardioverter defibrillator in children and young adults: Mortality and complications study

Young implantable cardioverter defibrillator (ICD) recipients have a high rate of complications, some of which seem to be underestimated. We report our clinical experience with ICD therapy in children and young adults during a 15 year follow up.

Left ventricular tumour masquerading as hypertrophic cardiomyopathy: how one can be misled by transthoracic echocardiography

Cardiac fibromas are common benign primary cardiac tumours in children. The incidence of these tumours is rare in the adult population but increases in patients suffering from Gorlin’s syndrome. These patients present with multiple basal cell carcinomas, ovarian fibromas, medulloblastomas, as well as skeletal abnormalities and congenital malformations. We present a case of a 41-year-old male with a longstanding history of heart failure in the course of hypertrophic cardiomyopathy (HCM) treated with implantable cardioverter-defibrillator (ICD), as primary prevention of sudden cardiac death, for seven years. At this point he was admitted to our clinic because of atrial and ventricular lead failure. The Heart Team decided on the transvenous lead removal strategy. During transoesophageal echocardiography performed intraoperatively a pathological mass in the right atrium was first encountered. Previous multiple transthoracic echocardiography (TTE) performed with poor echocardiographic window using only standard views as well as electrocardiogram (Fig. 1) did not drown suspicion of any pathology other than HCM. After ICD-VR re-implantation (intentional downgrading of CIED) a chest computed tomography (CT) was performed, which revealed the presence of a heart tumour with

Efficacy and tolerability of mexiletine treatment in patients with recurrent ventricular tachyarrhythmias and implantable cardioverter-defibrillator shocks

BACKGROUND Antiarrhythmic treatment of patients with recurrent ventricular tachyarrhythmia, in whom catheter ablation and amiodarone treatment were ineffective or contraindicated, is an unsolved clinical problem. AIM The study aims to evaluate the efficacy and tolerability of mexiletine in patients with recurrent ventricular tachyarrhythmias and/or electrical storm events, in whom standard treatment strategies failed to prevent ventricular tachyarrhythmia. METHODS We performed a retrospective cohort analysis of all patients treated with mexiletine for recurrent ventricular tachycardia and/or ventricular fibrillation in our institution between January 2011 and September 2015. The primary endpoints were total number of electrical storm events and ventricular tachycardia/ventricular fibrillation (VT/VF) episodes after the beginning of mexiletine therapy. Secondary endpoints were total number of implantable cardioverter-defibrillator (ICD) therapies and discontinuation of the therapy. Events were compared with a matched duration period before initiating mexiletine. Patients served as self-controls. RESULTS Seventeen patients were included in the study; 11 patients were males. Mean age was 64.2 ± 15.4 years. The median time of mexiletine treatment was eight months (interquartile range [IR]: 1-22 months). The mexiletine dose was 600 mg/day in 13 patients and 400 mg/day in four patients. In four patients the dose was modified during treatment in a range from 400 to 600 mg/day depending on clinical decision. Treatment with mexiletine significantly reduced the number of electrical storm events (14 episodes vs. two episodes; median and IR for 17 patients: 1 [0-1] vs. 0 [0-0], p = 0.0010), VT/VF episodes (285 vs. 74 episodes; median and IR for 17 patients: 7 [5-27] vs. 0 [0-5], p = 0.0115), and ICD interventions (317 interven-tions vs. nine interventions; median and IR for 17 patients: 10 [5-25] vs. 0 [0-2], p = 0.0006), in comparison with a matched period before initiation of treatment. In 14 out of 17 patients (82%) sufficient tolerability of mexiletine was observed. Only in three (18%) patients severe side effects of mexiletine treatment occurred requiring discontinuation of therapy. CONCLUSIONS Mexiletine was a sufficiently tolerated antiarrhythmic drug in short-term treatment of ventricular tachyarrhyth-mias in the studied population. Mexiletine may be effective in the treatment of recurring ventricular tachyarrhythmias or electrical storm events.

Effectiveness of antitachycardia pacing therapy after primary prophylaxis implantation of implantable defibrillators in coronary artery disease patients

PURPOSE Effectiveness of implantable defibrillators (ICD) has been proven with large randomized trials. Unfortunately, ICD discharge is painful and potentially threatening for the patient despite its life saving effects. We analyzed influence of the clinical parameters present before implantation on the effectiveness of antitachycardia pacing therapy (ATP) in terminating ventricular tachycardia (VT) slower than 200 bpm in the coronary artery disease patients with prophylactic implanted ICD in a single centre retrospective trial. PATIENTS/METHODS We analyzed 121 consecutive coronary disease patients with ICD implanted in primary prophylaxis between 2001 and 2007, with the mean age of 62 ± 10 years. The mean follow-up was 876 ± 538 days. RESULTS 32 of them had VT. In 27 persons (84.4%) at least one ATP attempt terminate VT. ATP was always successful in 21 patients. We analyzed age, sex, LVEF, NYHA class, widening of QRS complex, atrial fibrillation, type of myocardial infarction or diabetes. There were no significant differences in clinical features between patients with successful and unsuccessful ATP therapy. CONCLUSIONS High effectiveness of ATP was shown in this group. There were no clinical factors indicating success of this type of therapy. That could justify programming ATP as the first line therapy in the VT zone in primary prophylaxis coronary artery disease patients to reduce application of shock therapy. It should be possible to apply a single mode of programming when discharging patients after the implantation procedure regardless of the patients clinical condition. This could help to control and programme the devices, thus reducing the risk of errors.