Cation Effects on the Acidic Oxygen Reduction Reaction at Carbon Surfaces

Hydrogen peroxide (H2O2) is a widely used green oxidant. Until now, research has focused on the development of efficient catalysts for the two-electron oxygen reduction reaction (2e- ORR). However, electrolyte effects on the 2e- ORR have remained little understood. We report a significant effect of alkali metal cations (AMCs) on carbons in acidic environments. The presence of AMCs at a glassy carbon electrode shifts the half wave potential from -0.48 to -0.22 VRHE. This cation-induced enhancement effect exhibits a uniquely sensitive on/off switching behavior depending on the voltammetric protocol. Voltammetric and in situ X-ray photoemission spectroscopic evidence is presented, supporting a controlling role of the potential of zero charge of the catalytic enhancement. Density functional theory calculations associate the enhancement with stabilization of the *OOH key intermediate as a result of locally induced field effects from the AMCs. Finally, we developed a refined reaction mechanism for the H2O2 production in the presence of AMCs.

Accelerated development of a SEC-HPLC procedure for purity analysis of monoclonal antibodies using design of experiments

The complex structure of biopharmaceutical products poses an inherent need for their thorough characterization to ensure product quality, safety, and efficacy. Analytical size exclusion chromatography (SEC) is a widely used technique throughout the development and manufacturing of monoclonal antibodies (mAbs) which quantifies product size variants such as aggregates and fragments. Aggregate and fragment content are critical quality attributes (CQAs) in mAb products, as higher contents of such size heterogeneities impact product quality. Historically, SEC methods have achieved sufficient separation between the high molecular weight (HMW) species and the main product. In contrast, some low molecular weight (LMW) species are often not sufficiently different in molecular mass from the main product, making it difficult to achieve appropriate resolutions between the two species. This lack of resolution makes it difficult to consistently quantify the LMW species in mAb-based therapeutics. The following work uses a design of experiments (DoE) approach to establish a robust analytical SEC procedure by evaluating SEC column types and mobile phase compositions using two mAb products with different physiochemical properties. The resulting optimized procedure using a Waters™ BioResolve column exhibits an improved ability to resolve and quantify mAb size variants, highlighting improvement in the resolution of the LMW species. Additionally, the addition of L-arginine as a mobile phase additive showed to reduce secondary interactions and was beneficial in increasing the recoveries of the HMW species.

Establishment of a resazurin-based aortic valve tissue viability assay for dynamic culture in a microphysiological system

BACKGROUND/AIM

Tissue pathogenesis of aortic valve (AV) stenosis is research focus in cardiac surgery. Model limitations of conventional 2D culture of human or porcine valvular interstitial/endothelial cells (VIC/VECs) isolated from aortic valve tissues but also limited ability of (small) animal models to reflect human (patho)physiological situation in AV position raise the need to establish an in vitro setup using AV tissues. Resulting aim is to approximate (patho)physiological conditions in a dynamic pulsatile Microphysiological System (MPS) to culture human and porcine AV tissue with preservation of tissue viability but also defined ECM composition.

MATERIALS/METHODS

A tissue incubation chamber (TIC) was designed to implement human or porcine tissues (3×5 mm2) in a dynamic pulsatile culture in conventional cell culture ambience in a MPS. Cell viability assays based on lactate dehydrogenase (LDH)-release or resazurin-conversion were tested for applicability in the system and applied for a culture period of 14 days with interval evaluation of tissue viability on every other day. Resazurin-assay setup was compared in static vs. dynamic culture using varying substance saturation settings (50-300μM), incubation times and tissue masses and was consequently adapted.

RESULTS

Sterile dynamic culture of human and porcine AV tissue segments was established at a pulsatile flow rate range of 0.9-13.4μl/s. Implementation of tissues was realized by stitching the material in a thermoplastic polyurethane (TPU)-ring and insertion in the TIC-MPS-system. Culture volume of 2 ml caused LDH dilution not detectable in standard membrane integrity assay setup. Therefore, detection of resazurin-conversion of viable tissue was investigated. Optimal incubation time for viability conversion was determined at two hours at a saturated concentration of 300μM resazurin. Measurement in static conditions was shown to offer comparable results as dynamic condition but allowing optimal handling and TIC sterilization protocols for long term culture. Preliminary results revealed favourable porcine AV tissue viability over a 14 day period confirmed via resazurin-assay comparing statically cultured tissue counterparts.

CONCLUSIONS

Human and porcine AV tissue can be dynamically cultured in a TIC-MPS with monitoring of tissue viability using an adapted resazurin-assay setup. Preliminary results reveal advantageous viability of porcine AV tissues after dynamic TIC-MPS culture compared to static control.

Tired of feeling tired - The role of circulating inflammatory biomarkers and long-term cancer related fatigue in breast cancer survivors

BACKGROUND

Low-grade inflammation has been associated with cancer related fatigue (CRF). However, most studies focused on CRF during or shortly after treatment. Longitudinal studies are rare with inconsistent results. We assessed the association of inflammatory biomarkers with total CRF and all subdomains (physical, cognitive, affective) in long-term breast cancer survivors.

METHOD

Patients recruited between 2002 and 2005 provided information on CRF at first follow-up (FU1) (N = 1292) and second follow-up (FU2) (N = 1205), after a median of 6.2 years and 11.7 years, respectively. Associations of 11 inflammatory biomarkers with CRF at FU1 and at FU2 were assessed using linear regression models. Logistic regression models were used to compare patients fatigued at both time-points and those never fatigued (N = 932).

RESULTS

C-reactive protein (CRP) was significantly associated with total CRF at FU1 (β = 1.47, 95%CI = 0.62-2.31, p = 0.0007), at FU2 (β = 1.98, 95 %CI = 0.96-2.99, p = 0.0001) and with persistent CRF (OR = 1.29, 95%CI = 1.13-1.47, p < 0.0001). IL-6 levels were associated with total CRF at FU1 (β = 1.01, 95%CI = 0.43-1.59, p = 0.0006), but not with CRF at FU2 or persistent CRF. No association remained significant after adjustment for relevant covariates.

DISCUSSION

CRP and Il-6 were associated with risk of CRF in long-term breast cancer survivors, but were not independent of other known risk factors, suggesting that currently studied inflammatory markers are not suitable to identify patients at risk of long-term CRF.

Cardiogenic shock and radial access in patients with an acute ST elevation myocardial infarction

Background

Cardiogenic shock (CS) in patients (pts) with acute ST elevation myocardial infarction (STEMI) is the strongest predictor of hospital mortality. Radial in contrast to femoral access in STEMI pts might be associated with a lower mortality. However, little is known on radial access in CS pts.

Methods

We retrospectively analysed all STEMI pts between 2009 and 2015 who sufferend from CS and who were included into the ALKK PCI registry. Pts treated via a radial access were compared to those treated via a femoral access.

Results

Between 2009 and 2015 23796 STEMI pts were included in the registry. 1763 (7.4%) of pts were in CS. The proportion of radial access was 6.6%: in 2009 4.0% and in 2015 19.6%, p for trend &lt;0.0001 with a strong variation between the participating centres (0% to 37%).

Conclusions

Radial access was only used in 6.6% of STEMI pts presenting in CS. However, a significant increase in the use of radial access was observed over time (2009: 4%, 2015 19.6%, p&lt;0.001), with a great variance in its use between the participating hospitals. Despite similar pt characteristics the difference in hospital mortality according to access site has to be interpretated with caution.

Funding Acknowledgement

Type of funding source: None

Prognostic gene expression signature for high-grade serous ovarian cancer

BACKGROUND

Median overall survival (OS) for women with high-grade serous ovarian cancer (HGSOC) is ∼4 years, yet survival varies widely between patients. There are no well-established, gene expression signatures associated with prognosis. The aim of this study was to develop a robust prognostic signature for OS in patients with HGSOC.

PATIENTS AND METHODS

Expression of 513 genes, selected from a meta-analysis of 1455 tumours and other candidates, was measured using NanoString technology from formalin-fixed paraffin-embedded tumour tissue collected from 3769 women with HGSOC from multiple studies. Elastic net regularization for survival analysis was applied to develop a prognostic model for 5-year OS, trained on 2702 tumours from 15 studies and evaluated on an independent set of 1067 tumours from six studies.

RESULTS

Expression levels of 276 genes were associated with OS (false discovery rate < 0.05) in covariate-adjusted single-gene analyses. The top five genes were TAP1, ZFHX4, CXCL9, FBN1 and PTGER3 (P < 0.001). The best performing prognostic signature included 101 genes enriched in pathways with treatment implications. Each gain of one standard deviation in the gene expression score conferred a greater than twofold increase in risk of death [hazard ratio (HR) 2.35, 95% confidence interval (CI) 2.02-2.71; P < 0.001]. Median survival [HR (95% CI)] by gene expression score quintile was 9.5 (8.3 to -), 5.4 (4.6-7.0), 3.8 (3.3-4.6), 3.2 (2.9-3.7) and 2.3 (2.1-2.6) years.

CONCLUSION

The OTTA-SPOT (Ovarian Tumor Tissue Analysis consortium - Stratified Prognosis of Ovarian Tumours) gene expression signature may improve risk stratification in clinical trials by identifying patients who are least likely to achieve 5-year survival. The identified novel genes associated with the outcome may also yield opportunities for the development of targeted therapeutic approaches.

Validation of inflammatory genetic variants associated with long-term cancer related fatigue in a large breast cancer cohort

BACKGROUND

Studies to date have reported several associations between single nucleotide polymorphisms (SNPs) and cancer related fatigue (CRF), but have been limited by small sample sizes, missing adjustment for relevant covariates or multiple testing, as well as varying CRF definitions, i.e. time and method of assessment. This study aimed to validate previously reported associations using the largest independent breast cancer sample to date and to evaluate further functional cytokine variants in relation to total CRF and all relevant CRF subdomains (physical, cognitive, and affective CRF).

METHOD

45 candidate SNPs in inflammatory pathway genes were selected based on previous reports (16 SNPs) or regulatory function (29 SNPs). Breast cancer patients recruited between 2002 and 2005 provided information on CRF at first follow-up (FU1) (N = 1389) and second follow-up (FU2) (N = 950), a median of 6.2 years and 11.7 years respectively after diagnosis. SNP associations were assessed using linear regression models on CRF scores separately for FU1 and FU2. Additionally, patients with persistent fatigue (fatigued at both time-points) were compared to those never fatigued using logistic regression models (N = 684). All analyses were adjusted for relevant covariates. Secondary analyses were conducted for CRF subdomains.

RESULTS

For total CRF none of the previously reported associations were confirmed after correction for multiple testing. The p-value distribution of all SNPs was not different than the one expected by chance. Analyses of CRF subdomains yielded a significant association between TNF-α rs3093662 and persistent physical CRF (Odds Ratio (OR) = 3.23, 95% Confidence Interval (CI) = 1.71-6.10, p = 0.0003).

CONCLUSION

We were unable to confirm previously reported findings, suggesting that individual SNPs are unlikely to be of clinical utility. Further investigations in well powered studies are warranted, which consider genetic heterogeneity according to subdomains of CRF.

Highly efficient Tsuji–Trost allylation in water catalyzed by Pd-nanoparticles

Palladium nanoparticles stabilized by poly(vinylpyrrolidone) catalyze Tsuji–Trost allylations in water with very high turnover numbers.

Geochemistry and Mineralogy of Western Australian Salt Lake Sediments: Implications for Meridiani Planum on Mars

Hypersaline lakes are characteristic for Western Australia and display a rare combination of geochemical and mineralogical properties that make these lakes potential analogues for past conditions on Mars. In our study, we focused on the geochemistry and mineralogy of Lake Orr and Lake Whurr. While both lakes are poor in organic carbon (<1%), the sediments' pH values differ and range from 3.8 to 4.8 in Lake Orr and from 5.4 to 6.3 in Lake Whurr sediments. Lake Whurr sediments were dominated by orange and red sediment zones in which the main Fe minerals were identified as hematite, goethite, and tentatively jarosite and pyrite. Lake Orr was dominated by brownish and blackish sediments where the main Fe minerals were goethite and another paramagnetic Fe(III)-phase that could not be identified. Furthermore, a likely secondary Fe(II)-phase was observed in Lake Orr sediments. The mineralogy of these two salt lakes in the sampling area is strongly influenced by events such as flooding, evaporation, and desiccation, processes that explain at least to some extent the observed differences between Lake Orr and Lake Whurr. The iron mineralogy of Lake Whurr sediments and the high salinity make this lake a suitable analogue for Meridiani Planum on Mars, and in particular the tentative identification of pyrite in Lake Whurr sediments has implications for the interpretation of the Fe mineralogy of Meridiani Planum sediments.

KEY WORDS

Western Australia-Salt lakes-Jarosite-Hematite-Pyrite-Mars analogue. Astrobiology 16, 525-538.

Bifunctional hybrid catalysts derived from Cu/Zn-based nanoparticles for single-step dimethyl ether synthesis

Model kit for bifunctional catalysts: colloidal Cu/Zn-based nanoparticles were synthesized and used as building blocks in syngas to dimethyl ether (STD) catalysts.

Formation of chloroform and tetrachloroethene by Sinorhizobium meliloti strain 1021

The mechanisms and organisms involved in the natural formation of volatile organohalogen compounds (VOX) are largely unknown. We provide evidence that the common and widespread soil bacterium Sinorhizobium meliloti strain 1021 is capable of producing up to 3338·6 ± 327·8 ng l(-1) headspace volume of chloroform (CHCl3 ) and 807·8 ± 13·5 ng l(-1)  headspace volume of tetrachloroethene (C2 Cl4 ) within 1 h when grown in soil extract medium. Biotic VOX formation has been suggested to be linked to the activity of halogenating enzymes such as haloperoxidases. We tested if the observed VOX formation by S. meliloti can be attributed to one of its chloroperoxidases (Smc01944) that is highly expressed in the presence of H2 O2. However, addition of 10 mmol l(-1) H2 O2 to the S. meliloti cultures decreased VOX formation by 52% for chloroform and 25% for tetrachloroethene, while viable cell numbers decreased by 23%. Interestingly, smc01944 gene expression increased 450-fold. The quantification of extracellular chlorination activity in cell suspension experiments did not provide evidence for a role of S. meliloti chloroperoxidases in the observed VOX formation. This suggests that a momentarily unknown mechanism which requires no H2 O2 might be responsible for the VOX formation by S. meliloti. Regardless of the underlying mechanism our results suggest that the soil bacterium S. meliloti might be an important source of VOX in soils.

SIGNIFICANCE AND IMPACT OF THE STUDY

Volatile organohalogen compounds (VOX) strongly influence atmospheric chemistry and Earth's climate. Besides anthropogenic emissions they are naturally produced by either abiotic or biotic pathways in various environments. Particularly in soils, microbial processes drive the natural halogen cycle but the direct link to microbial VOX formation has not been studied in detail yet. In this study we provide evidence that the common and widespread soil bacterium Sinorhizobium meliloti strain 1021 forms chloroform and tetrachloroethene. The potential contribution of S. meliloti to soil VOX release could significantly influence soil and atmospheric chemistry.

[Deterministic record linkage with indirect identifiers: data of the Berlin Myocardial Infarction Registry and the AOK Nordost for patients with myocardial infarction]

AIM OF THE STUDY

How can 2 pseudonymised data sets be linked? Using the example of data from the Berlin Myocardial Infarction Registry and from a German sickness fund (AOK Nordost) we will demonstrate how record linkage can be achieved without personal identifiers.

METHODS

In different steps the method of deterministic record linkage with indirect identifiers: age, sex, hospital admission date and time, will be explained.

RESULTS

We were able to show that 80.6% of the expected maximum number of patients were matched with our approach. As a result we had no duplicate matches in the linkage process, where one AOK patient was linked to 2 or more BMIR patients or vice versa. The matching variables produced enough uniqueness to be used as indirect patient identifiers.

CONCLUSION

Deterministic record linkage with the following indirect indicators: age, sex, hospital admission date and time was possible in our study of patients with myocardial infarction in a circumscribed geographical region, which limited the number of cases and avoided mismatches.

Predominance of biotic over abiotic formation of halogenated hydrocarbons in hypersaline sediments in Western Australia

Volatile halogenated organic compounds (VOX) contribute to ozone depletion and global warming. There is evidence of natural VOX formation in many environments ranging from forest soils to salt lakes. Laboratory studies have suggested that VOX formation can be chemically stimulated by reactive Fe species while field studies have provided evidence for direct biological (enzymatic) VOX formation. However, the relative contribution of abiotic and biotic processes to global VOX budgets is still unclear. The goals of this study were to quantify VOX release from sediments from a hypersaline lake in Western Australia (Lake Strawbridge) and to distinguish between the relative contributions of biotic and abiotic VOX formation in microbially active and sterilized microcosms. Our experiments demonstrated that the release of organochlorines from Lake Strawbridge sediments was mainly biotic. Among the organochlorines detected were monochlorinated, e.g., chloromethane (CH3Cl), and higher chlorinated VOX compounds such as trichloromethane (CHCl3). Amendment of sediments with either Fe(III) oxyhydroxide (ferrihydrite) or a mixture of lactate/acetate or both ferrihydrite and lactate/acetate did not stimulate VOX formation. This suggests that although microbial Fe(III) reduction took place, there was no stimulation of VOX formation via Fe redox transformations or the formation of reactive Fe species under our experimental conditions.

Interventional treatment and outcome in elderly patients with stable coronary artery disease. Results from the German ALKK registry

BACKGROUND

The number of elderly and very elderly patients undergoing percutaneous coronary interventions (PCI) is increasing. We therefore analyzed data from the German ALKK registry (Arbeitsgemeinschaft Leitende Krankenhausärzte; Working Group of Hospital Cardiologists) to determine differences in procedural features, antithrombotic treatment, and in-hospital outcome in patients with coronary artery disease (CAD) according to age in a large series of patients.

METHODS AND RESULTS

The present analysis was based on the data of 35,534 consecutive patients undergoing elective PCI who were enrolled in the ALKK registry. Of these 27,145 (76.4 %) were younger than 75 years, 7,645 (21.5 %) were aged between 75 and 84 years, and 744 (2.1 %) patients were older than 85 years. Mean age was 68.5 years (60.9-74.5 years), and 25,784 patients (72.6 %) were male. Overall intraprocedural events were very low (1.1 %) and there was no significant difference between the three age groups [< 75 years (1.1 %); 75-< 85 years (1.2 %); ≥ 85 years (0.5 %) (p = not significant)]. Rates of in-hospital death, stroke and transient ischemic attack (TIA), as well as the combined endpoint in-hospital major adverse cardiac and cerebrovascular events (MACCE) were also very low (0.6 % vs. 0.9 % vs. 0.9 %; p < 0.001) but significantly higher in elderly patients with no further increase in the very elderly patient group.

CONCLUSION

We found no differences in this registry in intraprocedural complications during elective PCI between younger and elderly patients. Although in-hospital MACCE were somewhat higher in the elderly, the overall event rate was low and thus elderly patients should not be deprived from this therapy because of age alone.

Multiple cis-regulatory elements are involved in the complex regulation of the sieve element-specific MtSEO-F1 promoter from Medicago truncatula

The sieve element occlusion (SEO) gene family includes several members that are expressed specifically in immature sieve elements (SEs) in the developing phloem of dicotyledonous plants. To determine how this restricted expression profile is achieved, we analysed the SE-specific Medicago truncatula SEO-F1 promoter (PMtSEO-F1) by constructing deletion, substitution and hybrid constructs and testing them in transgenic tobacco plants using green fluorescent protein as a reporter. This revealed four promoter regions, each containing cis-regulatory elements that activate transcription in SEs. One of these segments also contained sufficient information to suppress PMtSEO-F1 transcription in the phloem companion cells (CCs). Subsequent in silico analysis revealed several candidate cis-regulatory elements that PMtSEO-F1 shares with other SEO promoters. These putative sieve element boxes (PSE boxes) are promising candidates for cis-regulatory elements controlling the SE-specific expression of PMtSEO-F1.

Modification of the circadian pattern of ventricular tachyarrhythmias by beta-blocker therapy

BACKGROUND

Sudden cardiac death exhibits a circadian variation and predominantly occurs during morning hours, Beta-adrenergic antagonists have shown to blunt this morning peak. However, previous reports studying the effects of beta blockers on the circadian variation did not analyze the underlying cause of sudden cardiac death. It thus remains unclear whether ventricular tachyarrhythmias are influenced by beta-blocker therapy.

HYPOTHESIS

This study tested the hypothesis that beta-blocking agents blunt the morning peak of life-threatening ventricular tachyarrhythmias.

METHODS

In 87 patients who were treated and monitored with an implantable cardioverter defibrillator, the circadian distribution of ventricular tachyarrhythmias terminated by appropriate shocks was analyzed and compared in those receiving beta blockers versus those not receiving beta-blocker therapy.

RESULTS

Tachyarrhythmic episodes in the absence of beta-blocker therapy (n = 344) exhibited a circadian variation with a distinct morning peak (16, 38, 28, and 18% of episodes at 0-6, 6-12, 12-18, and 18-24 h, respectively, p < 0.001). In contrast, tachyarrhythmic episodes during beta-blocker therapy (n = 104) were equally distributed over time (22, 27, 24, and 27% of episodes at 0-6, 6-12, 12-18, and 18-24 h, respectively, p = 0.95). The circadian distribution of episodes was significantly different in patients with and those without beta blockade (p < 0.05).

CONCLUSION

Beta-adrenergic antagonists influence the circadian distribution of malignant ventricular tachyarrhythmias in patients with an implantable cardioverter defibrillator. The blunted morning peak of tachyarrhythmic events during beta blockade supports the hypothesis that a sympathetic surge is involved in the circadian pattern of malignant arrhythmias.

Magnetocardiographic mapping of QRS fragmentation in patients with a history of malignant tachyarrhythmias

BACKGROUND

The identification of patients at increased risk for ventricular tachycardia or ventricular fibrillation (VT/VF) and sudden cardiac death has consequences for therapeutic options and thus may reduce mortality in patients with coronary artery disease (CAD).

HYPOTHESIS

We hypothesized that the intra-QRS fragmentation in magnetocardiographic recordings is increased in patients with CAD and with a history of VT/VF.

METHODS

Multichannel magnetocardiography (MCG) was carried out in 34 healthy controls, 42 patients with CAD without a history of VT/VF, and 43 patients with CAD and with a history of VT/VF. The intra-QRS fragmentation was quantified by a new fragmentation score. Its spatial distribution was investigated using two-dimensional (2-D) contour maps according to the sensor position of the 49-channel magnetogradiometer.

RESULTS

Patients with CAD and with a history of VT/VF had significantly increased QRS fragmentation compared with patients with CAD without VT/VF or controls (72.9+/-37.5, 48.5+/-14.3, and 42.5+/-7.8, respectively: p <0.05). The area of high fragmentation in 2-D contour maps was twice as large in patients with than in those without a history of VT/VF (represented by the number of MCG channels with high fragmentation: 26.3+/-15.5 vs. 12.4+/-9.9, p<0.0001). Patients prone to VT/VF could be identified with a sensitivity of 64% and a specificity of 90%.

CONCLUSION

In patients with CAD and with a history of VT/VF, intra-QRS fragmentation is increased and the area of high fragmentation in 2-D contour maps is enlarged. These findings may be helpful in identifying patients with CAD at risk for malignant tachyarrhythmias.

Analysis of terminal arrhythmias stored in the memory of pacemakers from patients dying suddenly

AIMS

Stored electrograms or marker channels are available in most of modern cardiac pacemaker models. We sought to analyse these information to uncover terminal events of pacemaker patients dying suddenly. Method and results We made post-mortem pacemaker (PM) interrogations in 19 patients dying suddenly out of hospital between the years 1997 and 2005 (mean age 59 +/- 13 years, 90% males). The systems had activated arrhythmia monitoring algorithms. Indications of pacing were sick sinus syndrome in seven, AV-block in five, and heart failure due to asynchrony in seven cases. The interrogated pacemakers were CHORUS 7034 (n = 12), CONTAK TR (n = 2), and INSYNC III (n = 5). For interpretation stored marker channels and electrograms were analysed. The mean observation time after PM implantation prior death was 2.11 +/- 1.44 years, the mean left ventricular ejection fraction from the last available echo examination in the year prior death was 27.5 +/- 8%, mean age was 63 +/- 12 years. In 17/19 cases (89%), a tachycardia (most likely ventricular tachycardia) was found correlating to the time of death. The mean cycle length of the terminal arrhythmia was 307 +/- 144 (250-344) ms, corresponding to a heart rate of 195 +/- 95 (174-240) bpm. We found no evidence of specific pacemaker-related problems such as electronic failure, battery depletion, or undersensing.

CONCLUSIONS

Post-mortem analysis of arrhythmia monitoring of pacemaker patients revealed tachycardias (most likely ventricular tachycardia) to be related to sudden death. These findings give some insight in mechanisms of terminal events in this group.

First experience with a new active fixation coronary sinus lead

AIMS

Coronary sinus (CS) lead implantation is a technically challenging procedure owing to variable vein anatomies and a high dislocation rate. Therefore, CS lead technology has undergone evolutionary changes during the last 10 years. The mode of fixation has been a passive one up to now. We want to describe our first clinical experience with the newly available active fixation lead 4195 in terms of dislocation rate and stability of thresholds compared with conventional models.

METHODS AND RESULTS

From 1999 to February 2007, we implanted 403 CS leads in 368 patients. Leads were categorized into three different groups on the basis of their fixation mechanism: straight (Easytrak I and Situs OTW; n = 54), curved (Attain 4193 and 4194, Corox, Aescula, Situs ULD; n = 308), and active (Attain 4195; n = 41). Operative and follow-up data were prospectively noted and checked for significance between groups during the first 3 months after implantation. Kaplan-Meier analysis of long-term lead function was also performed. Straight and curved CS leads suffered from significantly more dislocations compared with active fixation (P < 0.001). The active fixation lead (4195) has a stable threshold over time compared with a significant rise after 24 h and thereafter in straight (62%) and curved leads (20%). However, retraction of an active fixation CS lead may be a difficult issue as outlined in two cases requiring pullback of a 4195 lead owing to phrenic nerve stimulation (one unsuccessful despite vigorous traction).

CONCLUSION

The active fixation lead 4195 using retention lobes yielded stable thresholds over time and seems to be superior to conventional leads in terms of dislocation. However, extraction may be a difficult or even impossible task.

RHABDOMYOLYSIS AFTER ADDITION OF DIGITOXIN TO CHRONIC SIMVASTATIN AND AMIODARONE THERAPY

Rhabdomyolysis is a well known side effect of statin therapy. Several drugs may increase its risk by drug-drug interactions. In particular, patients with heart disease receive more and more different compounds to cope with all the pathomechanisms involved and may therefore be of high risk for side effects. We report a case of rhabdomyolysis in a patient with heart failure on a multi-drug regimen caused by a drug interaction between chronic statin therapy (simvastatin), amiodarone and newly administrated digitoxin. The patient recovered fully after cessation of simvastatin therapy, the other drugs were given continuously. Potential mechanisms of this event are discussed. Most interesting in this case is that rhabdomyolysis occurred only after starting digitoxin after long-term therapy with the statin.