Biomedical subjects
Publications and source records attributed to F Sacher.
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Biventricular resynchronisation is an additional therapeutic option in the management of refractory heart failure, with a functional and haemodynamic benefit as well as an improved morbidity and mortality. However, the rate of non-responsive patients has prompted a re-think about the presumed mechanisms of action for this procedure. This study aims to identify candidates more successfully. Based on five years experience in this centre, our work confirmed a medium and long term clinical benefit with multisite pacing. Nevertheless, there was evidence of a relative discordance between the functional benefit and the haemodynamic impact in terms of ejection fraction achieved with resynchronisation. While QRS narrowing appears to be a predictive factor for a successful procedure, the ECG alone is not sufficient to select 'unsynchronised' candidates. Statistical analysis reveals that before implantation the independent predictive factors to identify non-responsive patients include the presence of a complication of myocardial infarction and a low grade mitral leak. The limits of the ECG suggest a more mechanical than electrical approach to understanding the mechanisms of action for resynchronisation. Its effectiveness in cases of right bundle branch block confirm the hypothesis of left intra-ventricular conduction defects, not apparent on the surface ECG but accessible through new imaging techniques. Based on the hypothesis of delayed movement of the ventricular walls, the principle of resynchronisation aims to restore homogenous contraction. Echocardiography allows observation of electromechanical delay and opens new perspectives in the future for selecting patients for pacing. Ar
It has long been recognized that the formation of soluble arsenic sulfur complexes plays a key role for the mobility and toxicity of arsenic in sulfate-reducing environments. Knowledge of the exact arsenic species is essential to understand the behavior of arsenic in sulfidic aquifers and to develop remediation strategies. In the past, monomeric and trimeric thioarsenites were assumed to be the existing species in sulfidic systems. In this study, thioarsenates were identified by IC-ICP/MS in arsenite- and sulfide-containing solutions as well as in a reduced groundwater from a contaminated site. The unexpected finding of an oxidation of As(lll) to As(V) in thioarsenates in strongly reducing systems can be explained by the high affinity between As(Ill) and sulfur. In sulfide-containing solutions without oxidant, As(lll) therefore undergoes disproportionation to thioarsenates (As(V)) and elemental arsenic. It has previously been supposed that mobility as well as toxicity of arsenic increases if the redox state decreases. For sulfidic waters, the opposite is probably the case. Thus, the formation of thioarsenates could be used in connection with remediation strategies. Thioarsenates are highly sensitive to oxygen and pH. This is important for analytical procedures. A loss of soluble arsenic as well as a conversion to arsenite and arsenate may occur if water samples containing thioarsenates are analyzed with conventional methods.
Equilibrium and kinetic adsorption of methyl tert-butyl ether (MTBE) onto three coal-based activated carbons, one coconut-based activated carbon, and two zeolites are elucidated in this study. Natural organic matter (NOM) and MTBE competed for the adsorption of activated carbons to different extents. The ideal adsorbed solution theory (IAST) combined with the equivalent background compound (EBC) model can adequately describe the NOM competition and predict the isotherms of MTBE onto the activated carbons. No competitive adsorption was observed for one of the zeolites, mordenite, due to the molecular effect. Besides, the aperture size, and the SiO2/Al2O3 ratio of the zeolite may also play an important role in the adsorption of MTBE from the aqueous phase. The surface diffusion model accurately simulated the transport of MTBE within the adsorbents employed in different water matrices. For all the activated carbons tested, the surface diffusivity of MTBE in natural water was nearly equal to that in deionized water, indicating that no apparently hindering effect occurs. A much slower adsorption kinetic of mordenite in natural water was observed since the opening apertures on mordenite may be appreciably hindered and blocked by NOM.
Advances in echocardiography have paved the way for the development of intracardiac catheters with ultrasound transducers mounted on its tip. With this technology it has become possible for the interventional electrophysiologist to perform continuous echocardiographic examination during a procedure without the need for general anaesthesia or additional staff. Intracardiac echocardiography (ICE) allows the monitoring of catheter movement in real-time, assessment of catheter-tissue contact and potentially prevents and recognizes complications like thrombus formation and pericardial effusion. In addition recent technologies allow acquiring the full spectrum of Doppler-imaging permitting evaluation of haemodynamic data during the procedure. All these advances have made ICE an ideal tool for the interventional electrophysiologist, serving as a diagnostic and imaging tool during invasive electrophysiological procedures. This review will summarize currently available technology of ICE and its indications and applications in electrophysiological procedures.
UNLABELLED: The aim of this study is to characterize the electrocardiographic features of premature ventricular contractions (PVC) from different anatomical region that trigger ventricular fibrillation (VF). METHODS AND RESULTS: 36 consecutives patients (20 males, 42+/-14 yrs) undergoing VF ablation from 7 centres were studied (22 with idiopathic VF, 4 associated with a long QT syndrome, 3 with Brugada syndrome, 4 with ischaemic cardiomyopathy and 3 associated with other substrate). Mapping of these PVC showed 2 different origins, which were then confirmed by ablation: right ventricular outflow tract (RVOT) (22%) and peripheral Purkinje network (81%). One patient had PVC from both origins (Brugada). RVOT PVC were frequent but had triggered only 5+/-5 episodes of VF for 26+/-33 months. Purkinje PVC were more likely to be present during electrical storm with 18+/-28 episodes of VF for 33+/-45 months. Right Purkinje PVC have a left bundle branch block with superior axis morphology whereas left Purkinje ones have a right bundle branch block. The axis of activation showed variation from inferior to superior depending on the area of origin from the Purkinje network and the exit site to the myocardium. However Purkinje PVC were characterized by short QRS duration (126+/-18 vs 145+/-13ms for RVOT PVC; p=0.05). In addition the coupling interval was significantly shorter compared to RVOT PVC (292+/-45 vs 358+/-37ms respectively; p=0.005). CONCLUSION: PVC initiating VF demonstrate specific electrocardiographic features that facilitate determination of their origin. Ablation of these typical PVC is feasible in order to reduce ICD shock.
Endocavitary investigations showed that the ventricular extrasystoles originated in the common ventricular myocardium (pulmonary infundibulum) in only 9 cases whereas the majority arose from the Parkinje system either on the anterior wall of the right ventricle or in septal region of the left ventricle. The extrasystoles arising from the Parkinje system and pulmonary infundibulum differed in their duration and polymorphism (128 +/- 18 ms vs 145 +/- 13 ms, p = 0.05; 3.3 +/- 2.7 morphologies vs 1.1 +/- 0.4, p < 0.001, respectively). During the extrasystoles, the local Pukinje potential preceded the ventricular activation by variable intervals, some of which were very long, up to 150 ms. Seven applications of radiofrequency were delivered on average per patient on the most distal part of the Purkinje system leading to ablation of the specific activation. The clinical results were spectacular: 88% of patients had no further episodes of ventricular fibrillation as demonstrated by analysis of the defibrillator with an average follow-up period of more than 34 months.
Sudden cardiac death frequently results from ventricular fibrillation (VF). While VF is frequently the eventual mode of death in patients with abnormal ventricular substrates, it has also been described in patients with structurally normally hearts. Until recently, the management of patients who have survived sudden cardiac death has focused on treating the consequences by implantation of a defibrillator. However, such therapy remains restricted in many countries, is associated with a prohibitive cost to the community, and may be a cause of significant morbidity in patients with frequent episodes or storms of arrhythmia. Evidence emerging from the study of fibrillation both in the atria and the ventricle suggests an important role for triggers arising from the Purkinje network or the right ventricular outflow tract in the initiation of VF. Initial experience in patients with idiopathic VF and even those with VF associated with abnormal repolarization syndromes (LQT or Brugada syndrome) or myocardial infarction suggests that long term suppression of recurrent VF may be feasible by the elimination of these triggers. With the development of new mapping and ablation technologies, and greater physician experience, catheter ablation of VF, with the ultimate aim of curing such patients at risks of sudden cardiac death, may not be an unrealistic goal in the future.
Atrial fibrillation, the most common arrhythmia, is frequently disabling and drug resistant and is associated with significant complications, especially thromboembolic events. Non-pharmacological approaches including surgery and catheter-based ablation have been developed for the most symptomatic patients. These new treatment strategies have dramatically increased our knowledge of the pathophysiology of this arrhythmia but most importantly have demonstrated that atrial fibrillation is curable. Since 1994, 2 different concepts have been used, aiming to modify the substrate responsible for AF maintenance using linear lesions, or to ablate the triggers located from within the pulmonary veins (PV) in about 90% of cases. The vast majority of the laboratories in the world are now using approaches centred on isolation of the PV. These approaches are far from being perfect but good enough to be offered in routine practice to selected patients in experienced centres. The importance of PVs in the initiation of AF has been clearly demonstrated and they also have a possible role in the maintenance of AF. However, the existence of non venous foci or a prominent substrate for AF maintenance limits the success rate to about 70%. As a consequence, a combination of PV isolation and linear lesions is commonly used. This more complex procedure carries a significantly higher success rate however with an increased risk of tamponade. As a consequence, we need to identify which patients will require linear lesions in addition to PV isolation. At the present time, AF ablation is restricted to symptomatic patients who have failed at least 1-2 antiarrhythmic drugs but future technical improvements based on presently applied concepts are likely to widen the indications for ablation therapy of AF.
UNLABELLED: Catheter ablation techniques for atrial fibrillation have undergone an extensive evolution, starting with linear lesions in the right, then the left atria before being superseded by ablation of triggers, mainly from the pulmonary veins. We investigate the feasibility and results of combined pulmonary vein and linear ablation utilizing a specific linear lesion connecting the lateral mitral annulus to the left inferior pulmonary vein (left isthmus). METHODS: 115 patients (101 M: 54 +/- 9 years) with paroxysmal atrial fibrillation (7 +/- 5 years) resistant to 4 +/- 1.6 anti-arrhythmic drugs were studied. After electrophysiologically guided disconnection of all four pulmonary veins, the left isthmus line was performed with an irrigated tip catheter. Complete linear block was demonstrated during coronary sinus pacing by local mapping looking for widely separated double potentials and confirmed by differential pacing. Mapping and ablation from within the coronary sinus was performed if an epicardial gap was detected after unsuccessful endocardial radiofrequency delivery. RESULTS: 100% of pulmonary veins were successfully disconnected and the left isthmus line was complete with bi-directional block in 88% after a mean of 22 +/- 12 min of endocardial radiofrequency delivery in 44 patients. In 58 patients, additional radiofrequency delivery was required from within the coronary sinus for 5 +/- 5 min. After a follow-up of 6.5 +/- 2.6 months and a mean of 1.4 +/- 0.6 procedures/patient, 79% were in stable sinus rhythm without antiarrhythmic drugs. CONCLUSION: the left isthmus line is feasible and safe and when performed in addition to pulmonary veins isolation can contribute to an increased success rate.
In this paper, analytical methods for the trace-level determination of 60 pharmaceuticals in aqueous samples are presented. The list of compounds amenable to the methods comprises analgesics, antiphlogistics, antirheumatics, beta-blockers, broncholytics, lipid-lowering agents (or their metabolites), antiepileptics, vasodilators, tranquillizers, antineoplastic drugs, iodinated X-ray contrast media, and antibiotics of different kind, mainly sulfonamides, macrolides, and penicillins. All methods are based on automated solid-phase extraction followed by GC-MS (after derivatization of the acid compounds) or HPLC-electrospray ionization MS-MS. After an intense validation, which included the determination of performance data according to the German standard method DIN 32645 (limit of detection, limit of identification, limit of determination), the determination of linearity, recovery, and repeatability and the study of matrix effects, the analytical methods were applied within a monitoring program on the occurrence of pharmaceuticals in groundwaters of Baden-Württemberg. During this monitoring program, it was found that several of the compounds under investigation could be detected in groundwaters and their occurrence could be traced back to an impact of municipal or industrial waste water.
An ethanol extract derived from the roots of Eleutherococcus senticosus was found to influence markedly the cytokine synthesis of activated whole blood cultures of ten healthy volunteers. Whereas the synthesis of Rantes was increased over a wide range of concentrations, the release of IL-4, IL-5 and IL-12 was significantly inhibited. An inhibition at higher concentrations, switching to a stimulation at lower doses of the extract was seen with G-CSF, IL-6 and IL-13. From these particular immuno-pharmacological effects of Eleutherococcus senticosus we suggest this herbal preparation possesses immuno-modulatory potency, rather than just being immuno-suppressive or -stimulating.
Aliphatic and alicyclic amines as well as ethanolamines are extremely polar compounds, frequently found in the environment, and some of them have high toxicity. To address the contamination of selected German surface waters examined and the importance of bank filtration in Eastern Germany, investigations on the behaviour of polar organic nitrogen compounds during water treatment were carried out. Test conditions were designed appropriately for drinking water treatment conditions, and the tests were carried out using model water as well as bank filtrate. Test filter studies of microbial degradation of selected compounds demonstrated the following order of biodegradability: ethanolamine > dimethylamine > pyrrolidine > ethylenediamine. piperidine > diethylamine > morpholine > piperazine > cyclohexylamine. Flocculation tests using iron salts as well as aluminium salts as coagulants showed very low removal rates for the amines. The best results for the removal of the polar organic nitrogen compounds from the water were obtained using ozonation. Based on the reaction-rate constants, the order of degradation by ozone is: piperazine > morpholine > ethylenediamine > piperidine, cyclohexylamine > dimethylamine > ethanolamine > pyrrolidine > diethylamine. Disinfection by chlorine-containing agents under drinking water treatment conditions did not give effective elimination of the selected polar nitrogen compounds.
A liquid extract from Eleutherococcus senticosus roots inhibited the productive replication of human rhinovirus (HRV), respiratory syncytial virus (RSV) and influenza A virus in cell cultures infected with these viruses, all of which belong to the RNA type viruses. Analysis of virus production after treatment of the infected cells using plaque-reduction assays showed a strong antiviral activity of the Eleutherococcus extract. In contrast, no effect was detected using the same protocol for cells infected with the DNA viruses, adenovirus (Adeno 5) or herpes simplex type 1 virus (HSV 1). Pre-treatment of cells did not inhibit either virus adsorption or virus replication. The results of the study demonstrate that the Eleutherococcus extract inhibited the replication of all RNA viruses studied so far. This antiviral activity remained stable under the conditions used for drug preparation and storage.
As part of a project funded by the European Commission (EC) for the development and evaluation of multiresidue methods for analysis of drinking and related waters, 15 European laboratories evaluated a method using styrene-divinylbenzene co-polymer solid-phase extraction followed by gas chromatography/mass spectrometry. The main aim of the study was to evaluate whether the method meets the requirements of EC Directive 98/83 in terms of accuracy, precision, and detection limit for 22 pesticides according to the following requirements: limit of detection, < or = 0.025 microg/L; accuracy, expressed as recovery between 75 and 125%; and precision, expressed as repeatability relative standard deviation of the method of < 12.5% and as reproducibility relative standard deviation of the method of < 25%. Analyses for unknown concentrations were performed with fortified commercial bottled and tap waters. All laboratories were able to achieve detection limits of 0.01 microg/L for all pesticides except dimethoate and desisopropylatrazine (0.02 microg/L). The criteria for repeatability were met for all compounds except trifluralin, dimethoate, and lindane in bottled water and chlorpyrifos, dimethoate, and lindane in tap water. The criteria for reproducibility were met for all compounds except trifluralin, dimethoate, and lindane in bottled water and pendimethalin, chlorpyrifos, dimethoate, terbutryn, and lindane in tap water. In terms of accuracy, the method meets the requirements for all pesticides in both matrixes, except for lindane in bottled water and lindane and chlorpyrifos in tap water.