Rise in ICD Shock Impedance: Lead Fracture or Death?

Background: Remote monitoring allows for interrogation and extensive data retrieval of implantable cardioverter-defibrillators (ICDs). Data on ICD parameters at the time of death and afterwards are limited. The purpose of this retrospective study was to examine the changes in lead impedances of ICDs at the time of death and afterwards. Methods: A total of 37 Biotronik (SE & CO. KG, Berlin, Germany) ICDs (20 ICD-cardiac resynchronization therapy, 16 dual-chamber ICDs, and one single-chamber ICD), retrieved after death, were interrogated. Stored intracardiac electrograms were analyzed to determine the cause of death. Impedance trend curves of shock and pacing lead impedances were analyzed and correlated retrospectively with the reported time of death. The influence of cold exposure on lead impedances was tested in three other single-chamber Biotronik ICDs. Results: Of 37 patients, the cause of death was due to ventricular tachyarrhythmias in 21 patients. In 12 patients, death was not arrhythmia-related. In four patients, the cause of death could not be determined due to overwriting of the episodes at the time of death. A significant increase of shock and pacing lead impedances was observed in the postmortem days (P < 0.001 for all lead impedances). All lead impedance values increased significantly within the first postmortem day (P < 0.001 for all lead impedances). Cold exposure decreased shock lead impedance but did not affect pacing lead impedance. Conclusion: Postmortem analysis of ICDs allows tracking of lead impedance changes, which correlate with the day of death. The rise in postmortem impedances should not be interpreted as contributing to the mode of death. (PACE 2012; 35:1103-1110).     

Histological analysis of clipped human intracranial aneurysms and parent arteries with short-term follow-up

BackgroundSurgical clipping of intracranial aneurysms is the gold standard for the prevention of rupture. However, the biological processes that occur following clipping are poorly understood. To better understand these effects, retrieved and clipped human intracranial aneurysms were examined histologically.MethodsAt autopsy, 17 aneurysms from 10 patients were retrieved 3–21 days after clipping. The tissues were embedded in paraffin, and microtome sections were stained using hematoxylin–eosin and Movat pentachrome. Using light microscopy, clip placement relative to the internal elastic lamina of the parent artery, endothelialization of the aneurysm neck, thrombus organization inside the aneurysm sac, inflammation in the sac, wall, and parent artery, and atherosclerotic changes were determined.ResultsDespite complete reconstruction of the artery with the clip, diseased vessel wall was frequently observed outside the clip. By 10 days postsurgery, the beginnings of endothelialization and neointima formation were observed at the neck. However, the neck coverage was variable and incomplete at these early time points. Thrombus organization inside the aneurysm sac was rarely observed, and inflammatory cells were not present inside the aneurysm sac. Inflammatory cells were commonly observed in the aneurysm wall, and atherosclerotic change was present in each sample.ConclusionsComplete aneurysm exclusion and apposition of healthy arterial wall occurred infrequently in our series. Endothelialization and neointima formation at the aneurysm neck take some time to complete and are often incomplete. The effectiveness of aneurysm clipping is related to the mechanics of aneurysm exclusion rather than the processes of endothelialization and neointima formation.SummaryComplete aneurysm exclusion and apposition of healthy arterial wall occurred infrequently in our series. Endothelialization and neointima formation at the aneurysm neck take some time to complete and are often incomplete. The effectiveness of aneurysm clipping is related to the mechanics of aneurysm exclusion rather than the processes of endothelialization and neointima formation.     

Experimental spectro-angular mapping of light distribution in turbid media

We present a new approach to the analysis of radiance in turbid media. The approach combines data from spectral, angular and spatial domains in a form of spectro-angular maps. Mapping provides a unique way to visualize details of light distribution in turbid media and allows tracking changes with distance. Information content of experimental spectro-angular maps is verified by a direct comparison with simulated data when an analytical solution of the radiative transfer equation is used. The findings deepen our understanding of the light distribution in a homogenous turbid medium and provide a first step toward applying the spectro-angular mapping as a diagnostic tool for tissue characterization.     

Abalone viral ganglioneuritis: establishment and use of an experimental immersion challenge system for the study of abalone herpes virus infections in Australian abalone

In late 2005, acute mortalities occurred in abalone on farms located in Victoria, Australia. Disease was associated with infection by an abalone herpes virus (AbHV). Subsequently, starting in 2006, the disease (abalone viral ganglioneuritis; AVG) was discovered in wild abalone in Victorian open waters. Currently, it continues to spread, albeit at a slow rate, along the Victorian coast-line. Here, we report on experimental transmission trials that were carried out by immersion using water into which diseased abalone had shed infectious viral particles. At various time points following exposure, na?ve abalone were assessed by an AbHV-specific real-time PCR and histological analyses including in situ hybridization (ISH). Results demonstrated that while exposed abalone began displaying clinical signs of the disease from 60 hours post exposure (hpe), they tested positive for the presence of viral DNA at 36 hpe. Of further interest, the AbHV DNA probe used in the ISH assay detected the virus as early as 48 hpe.