[Acute coronary syndrome: when an indication for clopidogrel?].
Explore the source record for details and available documents.
Angina, Unstable↗
Biomedical subjects
R Köster
Publications and source records attributed to R Köster.
Experimental 16-row CT evaluation of in-stent restenosis using new stationary and moving cardiac stent phantoms: experimental examination.
PURPOSE: The aim of this study was to evaluate in-stent restenosiss using a newly developed stationary and moving cardiac stent phantom with three built-in artificial stenoses and a 16-row MDCT. MATERIALS AND METHODS: A newly developed coronary stent phantom with three artificial stenoses--low (approx. 30 %), medium (approx. 50 %) and high (approx. 70 %)--was attached to a moving heart phantom and used to evaluate the ability of 16-row MDCT to visualize in-stent restenosis. High resolution scans (16 x 0.75 mm, 250 mm FOV) were made to identify the baseline for image quality. The non-moving phantom was scanned (16 x 0.75 mm, routine cardiac scan protocol) first without and then with implementation of an ECG signal at various simulated heart rates (HR 40 to 120 bpm) and pitches (0.15 to 0.3). The moving cardiac phantom was scanned at the same simulated heart rates but at a pitch of 0.15. Images were reconstructed at every 10 % of the RR interval using a multi-cycle real cone-beam reconstruction algorithm. Multi-planar reformations (MPR) were made for the image evaluation. The image quality was assessed using a three-point scale, and stent patency and stenoses detection were evaluated using a four-point scale. To evaluate the image quality and to grade the stent stenoses, the median values were calculated while considering the reconstruction interval. RESULTS: The image quality for the static phantom was adequate in 97 % of the measurements. In this phantom, every stenosis was detected independent of the pitch and heart rate used. The dynamic stent phantom yielded the best results at 0 %, 40 %, and 50 % of the RR interval at a pitch of 0.15. The low stenosis was visible at a simulated heart rate of up to 80 bpm. Patency can be detected at heart rates greater than 80 bpm. CONCLUSION: The newly developed moving stent phantom allowed a nearly in-vivo condition for detecting re-stenoses within a stent. In this phantom study the use of a 16-row MDCT allowed the detection of re-stenosis within a coronary stent at a heart rate of up to 80 bpm. This phantom can then be used for future studies, e. g. with a 64-row MDCT.
Artifacts↗
[Preoperative cardiovascular evaluation before non-cardial surgery].
Explore the source record for details and available documents.
Cardiovascular Diseases↗
Evaluation of magnetic polymer micro-beads as carriers of immobilised biocatalysts for selective and stereoselective transformations.
The kinetic, selective and stereoselective properties of enzyme immobilised on magnetic polymer beads with diameters in the range 1 microm was studied with penicillin amidase from E. coli. The enzyme was immobilised on epoxy and glutaraldehyde-activated poly(vinyl alcohol), poly(methylmetacrylate) and poly(vinyl acetate-divinylbenzene) magnetic beads. The amount of covalently bound active protein was dependent on the chemical modification of the matrix and increased at higher ionic strength of the immobilisation buffer. The small size of the magnetic beads, that reduces mass transfer limitations, and the decreased charge density in the electric double layer resulted in lower apparent Km values and higher efficiency for benzylpenicillin hydrolysis, higher stereoselectivity in condensation of R-phenylglycine amide with S- and R-Phe and in hydrolysis of racemic phenylacetyl-Phe and higher selectivity in kinetically controlled synthesis of cephalexin compared to the enzyme immobilised on larger and porous carriers.
Binding Sites↗
Detection of aquatic colloids in drinking water during its distribution via a water pipeline network.
Laser-induced Breakdown Detection (LIBD) is a highly sensitive method for the direct detection of nano-particles (colloids). During the detection process plasmas are generated on single particles by a focused laser beam, the resulting plasma light emissions are detected optically. The method is based on the difference in breakdown thresholds of liquid and solid matter, it is lower for solid material. The laser pulse energy is adjusted precisely so that in the pure liquid no breakdown events occur, and only in the presence of colloids is the breakdown threshold in the focal volume exceeded. The spatial distribution of several thousand recorded plasma flashes within the focal volume reveals the mean particle diameter. The evaluation of the number of breakdown events per number of laser pulses results in a breakdown probability, together with the particle size the concentration is calculated using specially-designed computer software. Compared to conventional laser light scattering methods the LIBD is approximately 6 orders of magnitude more sensitive for particles smaller than ca. 0.05 pm. Together with laser light obscuration the LIBD technique has been used successfully for the quantification of aquatic nano-particles during drinking water processing and its distribution via a pipeline network of nearly 1,700 km total length. In addition, the particulate content of several brands of mineral water has been investigated.
Colloids↗
[Diagnosis and therapy of infectious endocarditis. What measures are required?].
Infectious endocarditis remains a potentially life-threatening disease, the outcome of which can be substantially influenced by rapid diagnosis and initiation of suitable treatment. Leading clinical features are fever, a new sound suggestive of valvular insufficiency and, when the course is subacute, anemia. The main diagnostic procedures are transthoracic and transesophageal echocardiography that reliably identify vegetation, valvular insufficiency and abscess. Of decisive importance for treatment and prognosis is the rapid identification of the pathogen by means of blood culture and, if necessary, serologic and molecular-biologic measures. Antimicrobial treatment is applied in accordance with the recommendations of the American Heart Association. Surgical treatment is indicated in the event of refractory infection, severe valvular insufficiency with heart failure, valve avulsion, recurrent emboli or large floating vegetation with an elevated risk of embolism.
Anti-Bacterial Agents↗
[Percutaneous revascularization of multivessel coronary disease using stents - a multicenter, prospective study].
BACKGROUND AND OBJECTIVE: Symptomatic patients with multivessel coronary disease (MVD) benefit from both coronary artery bypass grafting (CABG) and percutaneous coronary angioplasty (PTCA). The >>German Angioplasty Bypass Investigation<< (GABI-I) trial randomized patients to one of these treatment strategies between 1986 and 1991. In order to evaluate the impact of current technology, in particular coronary stents, the GABI-II trial was initiated, which in 1996 and 1997 prospectively enrolled patients according to the initial GABI-I criteria. PATIENTS AND METHODS: Into the study 136 consecutive patients (108 men, 28 women; 63 +/- 12 years) were included. Patients from GABI-I served as controls. RESULTS: A mean of 2.1 +/- 0.5 vessels were treated per patient (vs. 1.9 +/- 0.5 vessels in the PTCA arm of GABI-I) and 63 % of the lesions were covered with stents. With respect to the primary endpoint less patients remained with a CCS class III or IV in GABI-II after 12 months (1,5 % vs. 8 % in the PTCA arm of GABI-I, p<0,01). No patient required emergency or urgent bypass operation in GABI-II (vs. 9 % in GABI-I, p < 0.01). After 12 months, 8 % of the patients were sent for bypass surgery (CABG) vs. 21 % in GABI-I (p < 0.001), and 20 % (vs. 23 % in GABI-I) of the patients underwent Re-PTCA. The percentage of patients without reinterventions was 72 % vs. 56 % in GABI-I (p < 0.01), but remained lower compared to patients randomized to CABG in GABI-I (94 %, p < 0.001). CONCLUSION: PTCA in patients with MVD is still associated with a higher reintervention rate as compared with CABG. However, in contrast to angioplasty a decade ago, PTCA in conjunction with stents significantly lowered the need for subsequent revascularization, which was mainly driven by the reduced necessity for bypass surgery.
Aged↗
[Clinical manifestations of diffuse idiopathic skeletal hyperostosis (DISH)].
BACKGROUND: Diffuse idiopathic skeletal hyperostosis (DISH, Forestier disease) is in most cases a harmless, asymptomatic disease characterized by a massive, noninflammatory ossification with intensive formation of osteophytes affecting ligaments, tendons, and fasciae, especially of the spinal column. If the disease becomes symptomatic at all, the leading complaints will usually be dysphagia in the sense of a lump in the throat and difficulty in swallowing. However, in rare cases the osteophytes may influence the laryngeal function ranging from hoarseness and immobility of the vocal cord to life-threatening inspiratory stridor. Such laryngeal manifestations are almost unknown. PATIENTS AND METHOD: We report on three patients, two female and one male, suffering not only from chronic dysphagia but also from increasing inspiratory stridor and difficult breathing. RESULTS: Especially one case illustrates how difficult it can be to establish the etiological relationship between a cancer-like ulcer in the postcricoid region and a bilateral inactivity of the vocal cord on the one hand and DISH on the other hand. Only the resistance of the ulceration to any therapy as well as rare case reports in the literature confirmed our suspicion that the ulcer and disturbance of laryngeal function were caused by chronic pressure exerted by the huge vertebral osteophytes. In all three patients surgical resection of the osteophytes resulted in complete relief of complaints. CONCLUSION: Uni- or bilateral immobility of the arytenoids, possibly associated with chronic inflammatory hyperplasia of the tissue of the arytenoids and the postcricoid region, may be a symptom of an unusual manifestation of DISH.
Aged↗
Influence of particles on sonochemical reactions in aqueous solutions.
Numerous publications deal with the possible application of ultrasound for elimination of organic pollutants as a tool for water pollution abatement. Most of the experiments were performed in pure water under laboratory conditions. For developing technologies that hold promise it is necessary to investigate the effect of ultrasound in natural systems or waste water where particulate matter could play an important role. In this paper the influence of quartz particles (2-25 microm) on the chemical effects of ultrasound in aqueous system using a high power ultrasound generator (68-1028 kHz, 100 W, reactor volume 500 ml) is reported. In pure water in dependence on particle size, concentration and frequency the formation rate of hydrogen peroxide under Ar/O2 (4:1) shows a maximum using 206 kHz in presence of 3-5 microm quartz particles (4-8 g/l). Under these conditions the yield of peroxide is higher than without quartz. Additionally under N2/O2 (4:1) besides hydrogen peroxide the formation of nitrite/nitrate was measured. Compared to pure water quartz particle depressed the formation of nitrite/nitrate up to 10-fold but not the formation of H2O2. According to the results of H2O2 formation the elimination of organic compounds by sonolysis (206 kHz) and the influence of quartz particles were investigated. As organic compounds salicylic acid, 2-chlorobenzoic acid and p-toluenesulfonic acid were used. The influence of quartz on the oxidation of organic compounds (206 kHz) is similar to that on the formation of H2O2.
Journal Article↗
Antibodies to chlamydial lipopolysaccharides in unstable angina pectoris.
Patients with coronary artery disease frequently have elevated antibody titers against Chlamydia pneumoniae, but whether antichlamydial antibody titers are correlated with prognosis in unstable angina remains unclear. We therefore investigated the sera of 1,096 patients with unstable angina regarding immunoglobulin (Ig) IgG, IgA, and IgM antibody titers against chlamydial lipopolysaccharides (LPS) and the concentrations of C-reactive protein (CRP) and troponin T (TnT). Anti-LPS IgG titers were increased in 45% of patients at enrollment and in 48% of patients at discharge (p <0.0001). Anti-LPS IgA titers were increased in 27% of patients at enrollment and in 33% of patients at discharge (p <0.0001). Patients who subsequently died had significantly lower IgM titers at enrollment than patients without events (p = 0.016). IgG, IgA, or IgM titers did not correlate with concentrations of CRP or TnT. In this large-scale study of patients with unstable angina, we frequently found elevated antichlamydial antibody titers. Patients with low IgM anti-LPS titers were at risk for subsequent death. However, there was no correlation between antichlamydial antibody titers and CRP or TnT.
Aged↗
Membrane-covered stents: a new treatment strategy for saphenous vein graft lesions.
The restenosis rate after stenting of lesions in aortocoronary venous bypass grafts still has to be considered unsatisfactorily high. We investigated a new stent design characterized by an expandable polytetrafluorethylene (PTFE) membrane in between two layers of struts. Five consecutive male patients (age 70 +/- 6 years) were followed prospectively who presented with at least two de novo lesions in different grafts 13 +/- 3 years after bypass surgery. A total of 11 lesions were treated located in grafts anastomosed to the circumflex (n = 3), to the LAD (n = 7), and to the right coronary artery (n = 1). Within the same procedure, every patient received membrane-covered stents (n = 6) and conventional stents (n = 5) in either of their lesions. All patients underwent successful interventions. The minimal luminal diameter increased from 1.0 +/- 0.5 to 2.9 +/- 0.6 mm in lesions treated by the membrane-covered stents and from 0.8 +/- 0.4 to 2.4 +/- 0.7 mm in the lesions treated by conventional stents. During follow-up, four out of five patients required angioplasty for in-stent restenosis of lesions covered by a conventional stent, whereas no patient underwent revascularization for a lesion treated by a membrane-covered device. The mean minimal luminal diameter of lesions covered by a conventional stent decreased by 42% to 1.4 +/- 0.6 mm; the mean minimal luminal diameter of the lesions treated by a stent graft declined by 9% to 2.8 +/- 0.6 mm (P < 0.05). This series of intraindividual comparisons suggests that membrane-covered stents may have the power to reduce in-stent restenosis in obstructed aortocoronary venous bypass grafts.
Aged↗
Oxidative stress increases endothelin-1 synthesis in human coronary artery smooth muscle cells.
Endothelins, nitric oxide, and oxygen-derived free radicals decisively regulate vascular tone. An imbalance in the biosynthesis of these substances in pathophysiologic conditions may trigger vasospasm and promote the development of atherosclerosis. Previous studies have shown that oxygen-derived free radicals can increase the synthesis of endothelin-1 in cultured endothelial cells. Interestingly, conditions of increased oxidative stress within smooth muscle cells as induced by angiotensin II infusion or hypercholesterolemia have been shown to be associated with increased autocrine synthesis of endothelin-1. Because endothelin-1 formed in smooth muscle cells can trigger hypersensitivity to vasoconstrictors, we tested whether oxidative stress per se may affect endothelin expression in vascular smooth muscle cells. Cultured human coronary artery smooth muscle cells were exposed to oxidative stress generated by the xanthine/xanthine oxidase reaction or by hydrogen peroxide. Preproendothelin-1 mRNA content was quantitated by means of quantitative polymerase chain reaction and endothelin-1 protein was measured by radioimmunoassay. Incubation with xanthine/xanthine oxidase significantly increased preproendothelin-1 mRNA synthesis, whereas GAPDH remained unchanged. Likewise, xanthine/xanthine oxidase also led to a dose-dependent increase of intracellular endothelin-1. The increase in ET-1 expression induced by xanthine/xanthine oxidase was significantly inhibited by superoxide dismutase but not by catalase. We conclude that oxygen-derived free radicals can stimulate the synthesis of endothelin-1 in endothelial and vascular smooth muscle cells by increasing preproendothelin-1 mRNA content and that this effect is mediated predominantly by superoxide anions. We therefore have identified a new mechanism in the interaction of oxidative stress and endothelin-1 expression in smooth muscle cells that may have important implications in diseases such as atherosclerosis and hypertension.
Cells, Cultured↗
[The "Balthasar" pediatric hospice].
Explore the source record for details and available documents.
Adolescent↗
Nickel and molybdenum contact allergies in patients with coronary in-stent restenosis.
BACKGROUND: Coronary in-stent restenosis might be triggered by contact allergy to nickel, chromate, or molybdenum ions released from stainless-steel stents. We investigated the association between allergic reactions to stent components and the occurrence of in-stent restenosis. METHODS: Patients with coronary stainless-steel stents who underwent angiography for suspected restenosis were consecutively included in this study. Quantitative coronary angiography for analysis of percentage diameter stenosis was done on 131 patients (mean age 62 years [SD 9]) with 171 stents 6.1 months (2.7) after stent implantation. All patients underwent epicutaneous patch tests (Finn chamber method) for nickel, chromate, molybdenum, manganese, and small 316L stainless-steel plates. Patch tests were assessed by independent dermatologists after 48 h, 72 h, and when necessary 96 h of contact with the potential allergen. FINDINGS: In-stent restenosis (> or =550% diameter stenosis) occurred in 89 patients. All ten patients with positive patch-test results had restenoses (p=0.03). Four male patients had positive reactions to molybdenum, and seven patients (four male, three female) had reactions to nickel. No patient with an allergic reaction to the standard test substances had a positive reaction to the stainless-steel plates. All patients with positive results had recurrent angina pectoris and needed target-vessel revascularisation. INTERPRETATION: Patients with allergic patch-test reactions to nickel and molybdenum had a higher frequency of in-stent restenoses than patients without hypersensitivity. Allergic reactions to nickel and molybdenum released from stents may be one of the triggering mechanisms for in-stent restenosis.
Adult↗
Treatment of aortocoronary vein graft lesions with membrane-covered stents: A multicenter surveillance trial.
BACKGROUND: Stent implantation in lesions of degenerated aortocoronary vein grafts is associated with a high risk of periprocedural thrombus embolization and in-stent restenosis. METHODS AND RESULTS: In a multicenter study, we followed up 109 consecutive patients (mean age 66+/-8 years, 12% female) who received polytetrafluoroethylene (PTFE) membrane-covered stents for 125 de novo stenoses in vein grafts 11+/-5 years after bypass surgery. Stent deployment was successful in all but 1 patient; 1 patient suffered from subacute stent thrombosis. Six-month cardiac mortality was 7% (8 patients), 3 patients (3%) underwent repeat bypass surgery, and 9 patients (8%) required target-lesion PTCA. Repeat angiography revealed vessel occlusions in 9% and in-stent restenosis in 8% of patients by the end of follow-up. CONCLUSIONS: Membrane-covered stents appear to be a safe and efficient treatment strategy associated with a low incidence of restenosis and target-vessel revascularization. Compared with previous studies, the investigated device is not associated with an increase in mortality or late vessel occlusions.
Aged↗
[Myocardial revascularization for therapy-refractory angina pectoris in the elderly].
Explore the source record for details and available documents.
Aged↗
Initial experience with a hydrophilic-coated guidewire for recanalization of chronic coronary occlusions.
Chronic coronary occlusions are still a therapeutic challenge to the interventional cardiologist. New techniques such as laser wire have improved recanalization rates, but outcomes are still far from satisfactory. We report the results of a nonrandomized single-center investigation using a hydrophilic-coated guidewire (Terumo Crosswire). Between September 1996 and September 1998, 107 chronic occlusions in 106 patients were approached when previous attempts with conventional guidewires failed. Median occlusion duration in these cases was 4 months (range, 0.5-122); mean occlusion length was 19 +/- 11 mm (range, 5-60). Forty-five (42%) of these attempts were successful. Attempts were successful in 42% in the left anterior descending artery, in 30% in the left circumflex artery, in 48% in the right coronary artery, and in 43% in coronary artery bypass grafts. Success rates ranged from 56% for occlusions of less than 4-month duration to 18% for occlusions of more than 36-month duration. The success rate in TIMI 1-flow lesions was significantly higher than in TIMI 0 flow lesions, 85% vs. 36%. In a multivariate regression analysis, TIMI flow grade and occlusion age were independent predictors of success. There were no deaths or Q-wave myocardial infarctions; two cases of hemopericardium were treated successfully. In five cases, pericardial contrast staining due to vessel perforation occurred. Our results indicate that the Crosswire is an effective tool in the treatment of chronic coronary occlusions, even when recanalization attempts with conventional guidewires fail. Cathet. Cardiovasc. Intervent. 49:45-50, 2000.
Adult↗
Membrane-covered stents for the treatment of aortocoronary vein graft disease.
We report of a 78-year-old patient who underwent angioplasty for two de novo lesions in different aortocoronary venous bypass grafts. Whereas one lesion was treated by conventional stents, two adjacent lesions in a second bypass graft were covered by two newly designed stents with a polytetrafluorethylene (PTFE) membrane in between two layers of struts. The patient was first readmitted at month 5 with recurrent angina pectoris. High-grade in-stent restenosis of the lesion covered by the conventional stent was diagnosed, whereas the lesions treated by the membrane-covered stent revealed no restenosis. The patient underwent subsequent balloon angioplasty and was readmitted with unstable angina 8 months after the initial procedure. The angiogram revealed subtotal occlusion of the vein graft due to diffuse in-stent restenosis within the conventional stent. Undergoing re-PTCA, the patient received an additional membrane-covered stent placed over the proximal device. For the following 7 months, the patient stayed asymptomatic and underwent elective reangiography, which revealed a satisfying long-term result with no relevant luminal loss at the target site. This intraindividual comparison of stents in aortocoronary vein grafts suggests that PTFE membrane-covered stents might reduce restenosis as compared to conventional stents in venous bypass grafts. Furthermore, these stents potentially represent a new treatment strategy to fight in-stent restenosis in selected lesions.
Aged↗