Complications with the MICRA TPS Pacemaker System: Persistent Complete Heart Block and Late Capture Failure

A Medtronic MICRA transcatheter pacing system (Medtronic, Minneapolis, MN, USA) was implanted in an 86‐year‐old patient with sick sinus syndrome and left bundle branch block after transfemoral aortic valve implantation. During implantation she developed a persistent complete heart block due to manipulation with the large‐bore delivery catheter. Two weeks later, acute pacemaker dysfunction occurred due to massive increase of pacing threshold and impedance without obvious pacemaker dislocation or myocardial perforation. Recurrent capture failure was seen with pacing output set at 5 V/1.0 ms. Hence, microdislocation or fixation of the tines in the right ventricular trabeculae has to be assumed.     

Relevance of sequence statistics for the properties of extremophilic proteins

The amino acid composition of proteins from mesophilic and extremophilic organisms is commonly assumed to reflect the mechanisms of molecular adaptation to extremes of physical conditions. In this context, halo-philic behaviour has been attributed to significantly increased numbers of aspartic and glutamic acid residues. However, extending the analysis to a statistically relevant set of related proteins, dihydrofolate reductase from Halobacterium volcanii, as an example, shows that the increase in negative charge is found to be less significant than other exchanges of amino acids (e.g., Ala, Am, Arg, Lys, Phe, Ser). Thus, the high water binding capacity of negatively charged residues cannot be unambiguously correlated with the anomalous stability of halophilic proteins. A similar caveat holds for generalizations regarding the thermal stability of proteins. In this case, D-glyceraldehyde-3-phosphate dehydrogenase from the hyperthermophilic bacterium Thermotoga maritima was compared with a number of mesophilic and moderately thermophilic homologs. Again, ‘traffic rules of stabilization’, in terms of amino acid changes in going from mesophilic to thermophilic proteins, cannot be given.     

Sensing Lead Insulation Defect Resulting in a Damage of the ICD Pulse Generator Case

Eight months after ICD implantation with an electrically active case the patient presented with ICD system sensing failure. Upon re-operation, we found an insulation defect of the proximal sensing lead and the generator case showed arc marks suggesting a short circuit between the sensing lead and case. the generator was replaced, the original sensing lead insulated, and a new sensing lead inserted. Bench testing of the explanted generator showed a damaged internal circuitry. Proximal lead insulation defects combined with electrically active cases may result in damage of the case. The potential damage of internal circuitry warrants generator replacement.     

Complications of Third-Generation Implantable Cardioverter Defibrillator Therapy

To determine the incidence of complications of third-generation implantable cardioverter defibrillator (ICD) therapy, 144 patients were prospectively studied who underwent first implant of third-generation devices (i.e., ICD systems with biphasic shocks, ECC storage capability, and nonthoracotomy lead systems). During 21 ± 15 months of follow-up, 41 (28%) patients had one or more complications. No patient died perioperatively (30 days) and no ICD infection was observed during follow-up. Complications included bleeding or pocket hematoma (hemoglobin drop > 2 g/dL) in 5 (3%) patients, prolonged reversible ischemic neurological deficit in 1 (1%) patient, postoperative deep venous thrombosis of leg in 1 (1%) patient, pneumothorax in 2 (1%) patients, difficulty to defibrillate ventricular fibrillation intraoperatively in 2 (1%) patients, generator malfunction in 1 (1%) patient, arthritis of the shoulder in 3 (2%) patients, and allergic reaction to prophylactic antibiotics in 2 (1%) patients. A total of seven lead related complications were observed in six (4%) patients including endocardial lead migration in four (3%) patients. Twenty-three (16%) patients received inappropriate shocks for supraventricular tachyarrhythmias (n = 13), non-sustained ventricular tachycardia (VT) (n = 7), or myopotential oversensing (n = 3). We conclude that serious complications such as perioperative death or ICD infection are rare in patients with third-generation ICDs. Lead-related problems and inappropriate shocks during follow-up are the most frequent complications of third-generation ICD therapy. Recognition of these complications should promote advances in ICD technology and management strategies to avoid their recurrence.     

Anticardiolipin antibodies in rheumatoid arthritis: their relation to rheumatoid nodules and cutaneous vascular manifestations

One hundred and seventy-three consecutive patients with rheumatoid arthritis were examined for the presence of anticardiolipin antibodies (ACA), and for the clinical relevance and the relation of these antibodies to skin manifestations. Abnormally elevated IgG- and/or IgM-ACA levels were detected by an enzyme-linked immunosorbent assay in the sera of 55 (32%) patients. There was no statistical evidence of an association between ACA and a history of thrombosis in these patients. However, ACA were statistically significantly linked to the presence of rheumatoid nodules, which were found in 36 (21%) patients. In three patients, ACA were associated with vascular manifestations, including livedo reticularis, thrombophlebitis, and leucocytoclastic vasculitis. Our findings suggest that, although a subset of ACA may be linked to cutaneous vascular conditions, the major fraction of ACA in rheumatoid arthritis may have a different specificity than in other diseases, in which ACA are often linked to thrombotic events.     

Interference with Cardiac Pacemakers by Magnetic Resonance Imaging: Are There Irreversible Changes at 0.5 Tesla?

VAHLHAUS, C., et al. : Interference with Cardiac Pacemakers by Magnetic Resonance Imaging: Are There Irreversible Changes at 0.5 Tesla? The safety and feasibility of magnetic resonance imaging (MRI) in patients with cardiac pacemakers is an issue of gaining significance. The effect of MRI on patients' pacemaker systems has only been analyzed retrospectively in some case reports. Therefore, this study prospectively investigated if MRI causes irreversible changes in patients' pacemaker systems. The effect of MRI at 0.5 Tesla on sensing and stimulation thresholds, lead impedance and battery voltage, current, and impedance was estimated during 34 MRI examinations in 32 patients with implanted pacemakers. After measurements at baseline and with documentation of intrinsic rhythm and modification of the pacing mode, patients underwent MRI. The rest of the function time of the pacemaker was calculated. Measurements were again performed after 99.5 ± 29.6 minutes (mean ± SD), immediately after MRI examination, and 3 months later. Lead impedance and sensing and stimulation thresholds did not change after MRI. Battery voltage decreased immediately after MRI and recovered 3 months later. Battery current and impedance tended to increase. The calculated rest of function time did not change immediately after MRI. MRI affected neither pacemaker programmed data, nor the ability to interrogate, program, or use telemetry. Surprisingly, in the gantry of the scanner, temporary deactivation of the reed switch occurred in 12 of 32 patients when positioned in the center of the magnetic field. Missing activation of the reed switch through the static magnetic field at 0.5 Tesla is not unusual. MRI at 0.5 Tesla does not cause irreversible changes in patients' pacemaker systems.     

Surgery is inadvisable: Massive varicocele due to portal hypertension

The pathophysiology of idiopathic varicoceles as a dilatation of the pampiniform venous plexus has been traced to anatomical and embryological development, but is still unclear. Right or non-decompressible lesions are worrisome for retroperitoneal pathology, such as renal cell carcinoma, hydronephrosis, abdominal neoplasm or fibrosis. As a very rare finding we describe a patient who presented with an exorbitant left sided varicocele due to portal hypertension. We were well advised to avoid surgery.