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D Pfeiffer

Publications and source records attributed to D Pfeiffer.

At least 37 records · Page 2Linked to original sources
PubMed2001

Coagulation, fibrinolysis and platelet P-selectin expression in peripheral vascular disease.

OBJECTIVES: to examine coagulation, fibrinolysis, and platelet activity in patients with peripheral vascular disease (PVD). DESIGN: fifty consecutive PVD patients and 50 healthy volunteers. (Prospective comparative study.) MATERIALS AND METHODS: P-selectin expression in non-fixed, whole blood was measured flow cytometrically on non-stimulated and ADP- and TRAP-6-stimulated samples. Plasma fibrinogen, von Willebrand factor (vWF), tissue plasminogen activator (tPA), and plasminogen activator inhibitor-1 were determined using standard techniques. Disease severity was stratified on the basis of the ankle-brachial pressure index (ABPI) and the angiographic data were assessed using the Bollinger score. RESULTS: coagulation and fibrinolysis parameters as well as the P-selectin expression on both stimulated and non-stimulated platelets were significantly increased in patients vs controls (all p<0.01). The respective sensitivity and specificity were as follows: P-selectin expression (81%, 94%), vWF (72%, 86%), fibrinogen (64%, 98%), PAI-1 (44%, 90%), tPA (15%, 100%). P-selectin expression on TRAP-6-stimulated MP correlated with disease severity (r=0.40, p<0.01). CONCLUSIONS: these findings support the concept of ongoing thrombogenesis in the subclinical progression of PVD and demonstrate the high diagnostic sensitivity of flow cytometric analysis of platelet activation.

Blood Coagulation↗
PubMed2001

Surgical management of complications caused by transcatheter ASD closure.

BACKGROUND: Transcatheter occlusion of uncomplicated atrial septum defects (ASD) is recognized as an effective and minimally invasive method. Sometimes, serious early and late complications require surgical intervention. We therefore investigated reasons and outcomes of the secondary surgical approach. METHODS: 5 patients (aged 5-73 yrs) were admitted to our institution for device explantation and surgical ASD closure. ASDOS devices (A devices) had to be explanted in 4 patients and a SIDERIS "buttoned" occluder (S device) had to be explanted in 1 patient. The period from transcatheter implantation to surgical explantation ranged from 1 hour to 3 years. RESULTS: 3 patients (60 %) had to be operated in an emergency setting. In our youngest patient (5 yrs), the A device separated and embolized into the aorta and pulmonary artery. A pregnant women who needed emergent cesarean section developed hemopericard and tamponade due to atrial perforation by a fractured leg of an A device. In another A device, a suspect endocarditis caused membrane perforation. Malpositioning of an S device was the reason for operation. All patients recovered well without neurological symptoms. CONCLUSIONS: Transcatheter closure of uncomplicated ASD is a feasible alternative but surgical stand-by is essential. Nevertheless more complicated ASD should be operated, especially since the cosmetically satisfactory techniques of minimal invasive heart surgery are available.

Adult↗
PubMed2001

Decreased expression of epidermal growth factor receptor and mRNA of its ligands in Helicobacter pylori-infected gastric mucosa.

BACKGROUND: Epidermal growth factor (EGF) and TGF-alpha play a central role in maintaining gastric mucosal integrity. Little is known about the regulative role of the four other widely expressed epidermal growth factor receptor ligands, heparin-binding EGF, amphiregulin, betacellulin and cripto in the gastric mucosa. METHODS: Nineteen patients with Helicobacter pylori-positive gastritis and 32 healthy controls were investigated. Mucosal mRNA expression of EGF receptor ligands was determined by quantitative PCR before and after H. pylori eradication. PCR products were analyzed by soft laser scanning densitometry. Moreover, the effect of chronic active gastritis on EGF receptor expression was assessed by [125I] EGF receptor autoradiography. Immunohistochemistry was performed for TGF-alpha to localize growth factor expression. RESULTS: Antral and oxyntic biopsies showed strong mRNA expressions for TGF-alpha, amphiregulin and heparin binding EGF, but not for EGF, cripto and betacellulin. mRNA expression was significantly reduced down to 50% in H. pylori infection, significantly lower compared to normal gastric mucosa, and increased after eradication therapy. Moreover, chronic gastritis was associated with decreased antral EGF receptor binding compared to healthy controls, possibly reflecting reduced autoinduction. Immunohistochemical analyses localized TGF-alpha in the cytoplasma of gastric epithelial cells and revealed its increased expression after H. pylori eradication. CONCLUSIONS: The data presented suggest that amphiregulin, heparin binding EGF and TGF-alpha are important EGF receptor ligands in the gastric mucosa. H. pylori infection apparently suppresses their mRNA as well as receptor expression that is reversed by H. pylori eradication. This deficiency of the gastroprotective EGF system may contribute to the gastric pathogenicity of H. pylori infection.

Adult↗
PubMed2000

Transvenous biventricular defibrillation.

The recent success of biventricular pacing with transvenously implantable left ventricular leads suggests that left ventricular leads may be useful for other modes of therapy. Animal studies showed small leads inserted into a left ventricular vein dramatically reduced defibrillation strength requirements. This article describes a human investigation of the feasibility of biventricular defibrillation. Fifty-one patients undergoing implantable cardioverter defibrillator (ICD) implantation were enrolled. After insertion of a standard ICD lead, a prototype over-the-wire left ventricular defibrillation lead was inserted through the coronary sinus and into a vein on the left ventricle. Lead insertion was guided by retrograde venography. The left ventricular lead's location was randomized to the anterior or posterior vein. Randomized, paired defibrillation threshold (DFT) testing was performed to compare a standard ICD shock configuration (Control: right ventricle- --> superior vena cava+ + CAN+) to 1 of 3 biventricular shock configurations. In the anterior vein, the left ventricular lead was tested with either a single biphasic shock from right ventricle + left ventricle- --> superior vena cava+ + CAN+ or a dual biphasic shock. In the posterior vein, the left ventricular lead was tested with a dual biphasic shock. Dual shocks consisted of a 40% tilt biphasic shock from right ventricle- --> superior vena cava+ + CAN+ followed by another 40% tilt biphasic shock from left ventricle- --> superior vena cava+ + CAN+, delivered from a single 225 microF capacitance. Left ventricular lead positioning was successful in 41 of 46 patients (89%). Mean left ventricular lead insertion time was 17 +/- 17 minutes and 13 +/- 15 minutes for anterior and posterior locations, respectively. Mean DFTs were not statistically lower for the left ventricular shock configurations, but retrospective analysis showed a well-defined region of the posterolateral left ventricle where consistent DFT reduction was achieved with dual shocks (14.0 +/- 2.7 J vs 7.8 +/- 0.9 J; n = 5; p = 0.04). There were no adverse events requiring intervention due to the use of the left ventricular lead. Biventricular defibrillation is feasible and safe under the conditions used in this study. Additional studies are needed to verify whether dual shocks with posterolateral left ventricular lead positions consistently reduce DFTs.

Aged↗
PubMed2000

Principles and practical application of the receiver-operating characteristic analysis for diagnostic tests.

We review the principles and practical application of receiver-operating characteristic (ROC) analysis for diagnostic tests. ROC analysis can be used for diagnostic tests with outcomes measured on ordinal, interval or ratio scales. The dependence of the diagnostic sensitivity and specificity on the selected cut-off value must be considered for a full test evaluation and for test comparison. All possible combinations of sensitivity and specificity that can be achieved by changing the test's cut-off value can be summarised using a single parameter; the area under the ROC curve. The ROC technique can also be used to optimise cut-off values with regard to a given prevalence in the target population and cost ratio of false-positive and false-negative results. However, plots of optimisation parameters against the selected cut-off value provide a more-direct method for cut-off selection. Candidates for such optimisation parameters are linear combinations of sensitivity and specificity (with weights selected to reflect the decision-making situation), odds ratio, chance-corrected measures of association (e. g. kappa) and likelihood ratios. We discuss some recent developments in ROC analysis, including meta-analysis of diagnostic tests, correlated ROC curves (paired-sample design) and chance- and prevalence-corrected ROC curves.

Animal Diseases↗
PubMed2000

Synthesis and characterization of calcium complexes containing eta 2-pyrazolato ligands.

Treatment of calcium bromide with 3,5-di-tert-butylpyrazolatopotassium (2 equiv) in tetrahydrofuran afforded Ca(tBu2pz)2(THF)2 (69%). The reaction of this compound with pyridine (3 equiv), tetramethylethylenediamine (TMEDA, 1 equiv), N,N,N',N',N"-pentamethyldiethylenetriamine (PMDETA, 1 equiv), triglyme (1 equiv), and tetraglyme (1 equiv) yielded Ca(tBu2pz)2(py)3 (51%), Ca(tBu2pz)2(TMEDA) (74%), Ca(tBu2pz)2(PMDETA) (50%), Ca(tBu2pz)2(triglyme) (73%), and Ca(tBu2pz)2(tetraglyme) (57%), respectively. Treatment of the tetrahydrofuran adduct of Ca(Me2pz)2, generated in situ, with PMDETA (1 equiv), triglyme (1 equiv), and tetraglyme (1 equiv) afforded Ca(Me2pz)2(PMDETA) (65%), Ca(Me2pz)2(triglyme) (54%), and Ca(Me2pz)2(tetraglyme) (40%), respectively. The X-ray crystal structures of Ca(tBu2pz)2(py)3, Ca(tBu2pz)2(TMEDA), Ca(tBu2pz)2(PMDETA), Ca(tBu2pz)2(triglyme), and Ca(Me2pz)2(PMDETA) revealed six-, seven-, or eight-coordinate calcium centers with eta 2-pyrazolato ligands. Ca(tBu2pz)2(triglyme) sublimes at 160 degrees C (0.1 mmHg). The potential utility of these complexes as source compounds for chemical vapor deposition processes is discussed.

Journal Article↗
PubMed2000

[Alcohol concentration in the coronary sinus after transarterial ablation of septal hypertrophy in hypertrophic obstructive cardiomyopathy].

BACKGROUND AND OBJECTIVE: The size of the resulting myocardial necrosis varies after percutaneous transarterial ablation (PTA) of hypertrophied septum in patients with hypertrophic obstructive cardiomyopathy (HOCM). It was the aim of this study to discover whether the alcohol concentration in coronary sinus (CS) blood is a useful and appropriate parameter and what conclusions can be drawn from it. PATIENTS AND METHODS: PTA was done in four patients (two women and two men, aged 30-53 years) with HOCM. Before the intervention the gradient across the left ventricular outflow tract ranged form 20 to 80 mmHg, postextrasystolic it ranged from 40 to 180 mmHg. 1 x 2 ml ethanol was injected into the first septal branch in 3 patients, 2 x 2 ml in one. The alcohol concentration in coronary sinus blood was measured every 30 sec for up to 5 min before and after ablation. The amounts were compared with the size of the akinetic area in the echocardiogram and the maximal value of creatine kinase, as a measure of the size of myocardial necrosis. RESULTS: The left ventricular outflow gradient was reduced in all patients, to 0-30 mmHg and postextrasystolic to 30-90 mmHg. A pacemaker had to be implanted in one patient who developed a 3 degrees AV block. The alcohol concentration in coronary sinus blood ranged from maximally 1.53 and 0.23 per thousand after 30 sec and then fell to 0.56-0.12 per thousand after 5 min. The patient with the highest CS alcohol concentration also had the highest maximal value for creatine kinase (68 mumol/l) and the largest akinetic area in the echocardiogram. CONCLUSION: The extent of myocardial necrosis can probably be estimated from the CS blood concentration of alcohol after alcohol ablation. If, after the first injection, high alcohol concentrations are measured, further alcohol injections are not indicated.

Adult↗
PubMed2000

[Cardiac pacemaker therapy for optimizing brain circulation. A possible prevention for cerebrovascular diseases?].

HISTORY AND CLINICAL FINDINGS: A 78-year-old patient experienced dizziness, impairment of mnemic and cognitive function, chronic fatigue and recurrent syncope. INVESTIGATIONS: Hypertensive heart disease, reduced left ventricular function, and ventricular ectopia classification Lown IVb was documented. Computed tomography showed minimal brain atrophia. Stenoses of the brain supplying arteries and of other intracranial diseases were excluded. A distinct correlation between cardiac output and cerebral blood flow in correspondence to changes of heart rate were found (cardiac output 4.2 l/min during sinus rhythm, 7.4 l/min during temporary atrial pacing--AAI-Mode with a pacing rate of 90/min; 4.8 l/min--AAI-Mode with a pacing rate of 120/min; cerebral blood flow: 70, 74 and 62 ml/100 g per minute, respectively). Thus, impairment of cerebral blood flow autoregulation can be assumed. TREATMENT AND COURSE: After implantation of a permanent pacemaker the patient was without any complaints. The mnemic and cognitive function improved, dizziness and fatigue disappeared. Synopsis did not occur. 14 months later a sudden onset of complaints occurred caused by atrial fibrillation (heart rate 120/min). Cardiac output and cerebral blood flow were now 4.0 l/min and 35 ml/100 g per minute. After antiarrhythmic drug therapy and restoration of sinus rhythm cardiac output and cerebral blood flow increased and the complaints disappeared again. CONCLUSION: In patients with impaired capacity of cerebral autoregulation a reduced cardiac function and output can induce a reduction of cerebral blood flow. Thus, impairment of mnemic and cognitive function as well as other unspecific neurological deficits can be caused. In these cases pacemaker therapy has to be discussed as an effective therapeutical concept.

Aged↗
PubMed2000

[Fractional flow reserve as a deciding criterion for intervention in patients with 50% coronary stenoses and impaired myocardial perfusion].

BACKGROUND: A fractional flow reserve (FFRmyo) < 0.75 is a well validated parameter for significance of coronary stenoses in cases of normal myocardial function. We used the FFRmyo limit in patients with impaired myocardial perfusion by myocardial infarction and/or hypertension for intermediate stenoses of the LAD for decision to PTCA and checked the indication by clinical follow-up. METHODS: In 20 pts (5 women) with chest pain and visual 50 D% LAD stenoses, the FFRmyo was obtained by using a RADI-Pressure-Wire, the CFR by a densitometric technique (HODGSON), and the geometry of stenosis (minimal lumen diameter and diameter stenosis) by quantitative coronary angiography (QCA). EF and the kinetics of the anterolateral wall (expressed as radial shortening fraction) were measured by laevography. RESULTS: The mean age of our 20 pts. was 59.4 years: 13 of the pts. (65%) had a history of hypertension, 9 (45%) pts. a history of myocardial infarction. The mean diameter stenosis was 50.8%. The mean value of CFR was 2.9. The FFRmyo ranged from 0.66 to 0.90, the mean value was 0.78. The 12 pts. with FFRmyo > or = 0.75 (60%, group A) were treated with the usual anti-anginal medications. A PTCA was performed only in patients with FFRmyo < 0.75 (N = 8 (40%), group B). Except for one pt. with instent restenosis, in the 7 pts. with denovo stenoses stent implantation was performed. Significant differences between the groups A and B were seen only for the total number of myocardial infarctions (8/12 vs. 1/8) and diameter stenosis (48.5% vs. 54.3%). All lesions of group B had a diameter stenosis of 50% or higher. CFR correlated significantly with the radial shortening fraction (r = 0.75), minimal lumen diameter (r = -0.51) and diameter stenosis (r = -0.46). FFRmyo correlated with diameter stenosis (r = -0.47) only. All pts. treated with PTCA were primarily free of pain or reduced angina at least 1 CCS stage; only one developed an angina due to a restenosis (74 D%) 2 months after PTCA and stent implantation. The pts. of group A did not get worse, nor were they readmitted within 6 to 13 months after catheterization. CONCLUSIONS: Pts. with 50 D% stenoses, impaired myocardial perfusion and FFRmyo < 0.75 had a good long-term benefit concerning clinical and angiographic result. No pts. with FFRmyo < 0.75 had a D% lower than 50; therefore, the PTCA of intermediate stenoses without quantification must be avoided. CFR is not helpful for a decision to PTCA in such cases, because a normal value of CFR is relevant only.

Aged↗
PubMed2000

[Catheter ablation of supraventricular tachyarrhythmias].

The term "supraventricular tachyarrhythmia" summarizes electrophysiologically different arrhythmias. After detection of the mechanism of the present arrhythmia, the weak part of the reentrant circuit has to be identified using different mapping techniques. The catheter ablation is widely used as focal ablation (sinus tachycardia, ectopic atrial tachycardia, focal atrial fibrillation) or for interruption of conducting pathways (accessory pathways, AV nodal reentrant tachycardia). A single ablation line should be created in isthmus-dependent atrial flutter or in incisional tachycardias, which is less used now-a-days. Multiple ablation lines are needed for ablation of atrial fibrillation, which is a method investigated in arrhythmia centers only. Some arrhythmias are less well understood, not localizable and therefore not curatively treated with ablation techniques. Newer three-dimensional mapping methods may help in this situation. The challenge at the present time is the catheter ablation of atrial fibrillation.

Catheter Ablation↗
PubMed2000

Radiofrequency ablation of atrioventricular nodal reentrant tachycardia: mechanisms and recurrence rate.

Radiofrequency catheter ablation is the treatment of choice in atrioventricular nodal reentrant tachycardia. Electrophysiologic investigations in 623 patients revealed eight mechanisms of tachycardia ablation: Ablation of fast (I) or slow (II), modification of fast (III) or slow AV nodal pathways (IV), modification of both pathways (V), ablation of fast and modification of slow (VI), ablation of slow and modification of fast pathways (VII) and ablation of both pathways (VIII). The criteria of diagnosis of these eight mechanisms of tachycardia ablation are described. Follow-up showed fewer relapses in patients with ablation (0-2%) in comparison to patients with modification of a single AV nodal pathway (8-12%). Alteration of both pathways includes an increasing risk of total AV nodal block, which occurred in 7 patients (1.1%). Detailed analysis of the mechanism of catheter ablation is recommended in all patients after radiofrequency current delivery for AV nodal reentrant tachycardia to estimate the risk of relapse during follow-up or development of total AV block in the particular patient in case of a further ablation procedure.

Catheter Ablation↗
PubMed2000

Implantable dual-chamber cardioverter-defibrillator-pacemaker.

The fifth generation of implantable cardioverter-defibrillators offer enhanced modes of detection of atrial and ventricular arrhythmias, antitachycardia pacing and shocks, multiprogrammability, intracardiac electrogram storage, and all functions of antibradycardia dual-chamber pacing including rate responsiveness and mode switching. There is no consensus on the indications for dual-chamber pacemaker defibrillator systems. This review focuses on the four major options of newer devices that might benefit patients: 1) permanent dual-chamber pacing in ischemic coronary disease patients, 2) detection and management of atrial fibrillation or other atrial tachyarrhythmias, 3) some newer indications for pacing, and 4) the suppression of inappropriate interventions. On the basis of published data, newer indications for the dual-chamber systems, advantages and limitations, and future perspectives are discussed.

Atrial Fibrillation↗
PubMed2000

P-Selectin expression, platelet aggregates, and platelet-derived microparticle formation are increased in peripheral arterial disease.

Platelet volume has been reported to be increased in vascular disease. Therefore, we studied the relationship of mean platelet volume and platelet count as well as flow cytometrically measured platelet size and platelet function in 50 patients with peripheral arterial disease and 50 healthy volunteers. Platelet activation was measured by P-selectin expression analysis on resting and on stimulated platelets, and the determination of platelet aggregates and platelet-derived microparticles using flow cytometry. P-Selectin expression on platelets was significantly elevated in patients suffering from peripheral arterial disease (all P<0.0001). Platelet aggregates (P<0.0001) and platelet-derived microparticles (P<0.0001) were significantly higher in the patient group compared with controls, whereas mean platelet volume and platelet count showed no significant differences. Platelet count was inversely related to mean platelet volume in patients and controls (r = -0.43, P<0.001). The present study supports the hypothesis of platelet hyperreactivity and circulating activated platelets in peripheral arterial disease. Mean platelet volume, and platelet count cannot be used as predictive markers for platelet activation in peripheral arterial disease patients.

Adult↗
PubMed2000

Bimodal RR interval distribution in chronic atrial fibrillation: impact of dual atrioventricular nodal physiology on long-term rate control after catheter ablation of the posterior atrionodal input.

INTRODUCTION: Radiofrequency (RF) catheter modification of the AV node in patients with atrial fibrillation (AF) is limited by an unpredictable decrease of the ventricular rate and a high incidence of permanent AV block. A bimodal RR histogram has been suggested to serve as a predictor for successful outcome but the corresponding AV node properties have never been characterized. We hypothesized that a bimodal histogram indicates dual AV nodal physiology and predicts a better outcome after AV node modification in chronic AF. METHODS AND RESULTS: Thirty-seven patients were prospectively subdivided into two groups according to the RR histogram of 24-hour ECG monitoring. Before to RF ablation, internal cardioversion and programmed stimulation were performed. Among the 22 patients (group I) with a bimodal RR histogram, dual AV nodal physiology was found in 17 (77%) patients. Ablation significantly decreased ventricular rate with loss of the peak of short RR cycles after ablation (mean and maximal ventricular rates: 32% and 35% rate reduction, respectively; P < 0.01). In 15 patients with a unimodal RR histogram (group II), dual AV nodal physiology was found in 2 (13%), and rate reductions were 16% and 17%, respectively. At 6 months, 3 (14%) patients in group I and 6 (40%) in group II underwent elective AV nodal ablation with pacemaker implantation due to intolerable rapid ventricular response to AF. CONCLUSION: Bimodal RR interval distribution during chronic AF suggests the presence of dual AV nodal physiology and predicts a better outcome of RF ablation of the posterior atrionodal input.

Adult↗
PubMed2000

Lipopolysaccharides do not alter metabolic disturbances in hippocampal slices of fetal guinea pigs after oxygen-glucose deprivation.

The aim of the present study was to clarify whether endotoxins [lipopolysaccharides (LPS)] have a toxic effect on fetal brain tissue after cerebral ischemia, while excluding their effect on the cardiovascular system. Experiments were therefore performed on hippocampal slices prepared from mature fetal guinea pigs. In particular, we studied the influence of LPS on nitric oxide production, energy metabolism, and protein synthesis after oxygen-glucose deprivation (OGD). Incubating hippocampal slices in LPS (4 mg/L) for as long as 12 h did not alter cGMP tissue concentrations significantly. However, 10 min after OGD of 40-min duration, cGMP tissue concentrations were substantially increased in relation to controls, and this increase was almost completely blocked by the application of 100 microM N:(omega)-nitro-L-arginine, indicating that nitric oxide synthase was activated after OGD in fetal brain tissue. Again, LPS did not have any effect on cGMP tissue concentrations after OGD. Furthermore, addition of LPS altered neither protein synthesis nor energy metabolism measured 12 h after OGD. We therefore conclude that, apart from their well-known influence on the cardiovascular system, LPS do not alter metabolic disturbances in hippocampal slices of fetal guinea pigs 12 h after OGD. A direct toxic effect of LPS on immature brain tissue within this interval does not therefore seem to be very likely. However, delayed activation of LPS-sensitive pathways that may be involved in cell death, or damage limited to a small subgroup of cells such as oligodendrocyte progenitors, cannot be fully excluded.

Adenosine Triphosphate↗
PubMed2000

Changes in signal transduction in the platelets of patients with peripheral occlusive arterial disease.

BACKGROUND: The finding that platelets of patients with peripheral occlusive arterial disease (POAD) circulate in an activated state prompted us to study platelet signal transduction. We hypothesised that platelet hyperreactivity is caused by changes in intracellular signalling. METHODS EXPERIMENTAL DESIGN: a single blood sample was taken from the antecubital vein of each participant prior to the start of intravenous treatment with prostaglandins. SETTING: patients were recruited from our inpatient Department of Cardiology and Angiology at the University Hospital. PARTICIPANTS: 15 hospitalised patients with symptomatic POAD were randomly selected. Patients receiving antiplatelet drugs and those with diabetes were excluded. The control group consisted of 15 healthy volunteers from the medical staff. INTERVENTIONS: blood tests were performed on the day of admission before any therapeutic intervention. MEASURES: the platelet activation marker P-selectin was quantified on peripheral blood platelets before and after in vitro stimulation with platelet agonists (adenosine diphosphate, thrombin receptor activator peptide-6). The signal transduction cascade was also selectively blocked by preincubation with either: 1) forskolin, 2) phospholipase C inhibitor U-73122, or 3) bisindolylmaleimide. RESULTS: A stronger inhibitory effect on ADP-stimulated platelets was seen in patients with U-73122, as indicated by a decrease in mean fluorescence intensity of 51% versus 34% in controls (p<0.0005). CONCLUSIONS: Our findings support the assumption that changes in platelet signal transduction in POAD lead to platelet hyper-reactivity.

Adenosine Diphosphate↗