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  • Nonaka et al have described that


    Nonaka et al. have described that the right diaphragm is greatly elevated, the left ventricle tends to move vertically, and the ascending Aminoallyl-UTP moves to the right side after a right upper lobectomy [9]. In this patient, Aminoallyl-UTP it was unknown whether the right upper lobectomy resulted in the observed descending aorta displacement.
    Conflict of interest
    Introduction Implantable cardioverter-defibrillators (ICDs) are indicated for the prevention of sudden cardiac death in patients with an inherited channelopathy and high-risk factors, such as history of resuscitated sudden cardiac death, malignant ventricular arrhythmias, and family history of a malignant genetic phenotype [1,2]. With proven mortality benefits in a range of patient populations, the use of ICDs has increased dramatically over the years, and a major concern now is the long-term reliability of ICD systems.
    Case report On 5th August 2008, the patient had yet another VF arrest, which was successfully controlled by her ICD. Device interrogation revealed appropriate detection of VF, with an initial unsuccessful defibrillation attempt followed by a successful 31-joule shock (Fig. 1). All lead impedances were found to be markedly lower than the routine measurements made by the device up to and including the day of the ICD shock (Fig. 2). Additionally, the sensing was unchanged; the capture threshold of the atrial lead had risen from 0.8 to 1.2V at 0.4ms; and the ventricular pace/sense lead failed to capture at the maximal output. Chest radiography did not furnish any evidence of lead conductor fracture or insulation breach (Fig. 3). On revision of her ICD system, insulation breaches were identified in the portions of both the atrial and ventricular leads within the pre-pectoral pocket, along with a clear “arc mark” on the ICD generator casing, which was consistent with a high-voltage electrical discharge through a short circuit between the denuded right ventricular lead and the casing (Fig. 4). The right atrial lead was successfully extracted, but the extraction of the right ventricular lead was unsuccessful. Thereafter, a new ICD system was successfully implanted.
    Discussion Long-term data on ICD lead survival are disappointing with regard to ICD lead longevity, but the conclusions are confounded by varying definitions of lead failure and heterogeneity in the ICD lead models studied [3,4]. In early studies, lead failure rates have been reported to be as high as 18% at 4 years; 19% at 5 years; and 38% at 8 years, with a coaxial lead design highlighted as a particular risk. More recent studies have included patients with multi-lumen ICD leads [5,6]. Kleemann and colleagues, for example, prospectively followed a large cohort of patients who underwent implantation of 19 different ICD leads between 1992 and 2005. Estimated lead survival rates at 5 and 8 years after implantation were 85% and 60%, respectively, with the annual lead failure rate increasing with time after implantation to reach 20% after 10 years. A younger age was associated with a higher rate of lead failure, and female gender was strongly associated with elevated risk [5]. Younger age and female gender have likewise been reported as risk factors for lead failure by other investigators, for example, Hauser and colleagues, in their multicentre review of Medtronic Sprint Fidelis lead failure [7]. Dysfunction may develop in any component of the ICD lead, but a defect in lead insulation remains the most common problem [5,6]. Insulation with polyurethane, which has outstanding tensile strength, facilitates the manufacture of leads with small diameters. Poor biostability resulting in polymer degradation does, however, increase the risk of insulation breaches, and most studies have reported an association between polyurethane insulation and insulation failure [8,9]. Silicone rubber insulation is biologically more stable, but is more vulnerable to mechanical injury. A particular issue with this type of insulation is longitudinal insulation creep [10] at pressure points, such as between the clavicle and first rib or, as in our case, where a lead makes contact with the generator in the pocket.