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Biomedical subjects

B Meier

Publications and source records attributed to B Meier.

At least 217 records · Page 12Linked to original sources
PubMed1996

High dose dipyridamole as a pharmacological stress test during cardiac catheterisation in patients with coronary artery disease.

AIM: To validate dipyridamole as a pharmacological stress test during cardiac catheterisation, allowing both functional and morphological estimation of stenosis severity. METHODS: The study encompassed 74 patients: 62 patients with significant coronary artery disease (age 61 (SD 8) years; seven women, 55 men) and 12 controls. Regional wall motion, left ventricular ejection fraction and end diastolic pressure were analysed in the resting state and after high dose intravenous dipyridamole. Patients were subdivided into four groups: group I (n = 32, 43%) had stopped all anti-ischaemic treatment for > 24 h, group II (n = 14, 19%) was under treatment, group III (n = 16, 22%) had significant coronary artery disease only in regions with regional wall motion abnormalities at rest, and group IV consisted of 12 control patients (16%) with no significant coronary artery disease (age 62 (8) years, three women, nine men). RESULTS: The sensitivity of dipyridamole testing in patients with coronary artery disease was poor. The best sensitivity was obtained with regional wall motion analysis (26/62 = 42%) and with global left ventricular ejection fraction (25/62 = 40%). Specificity was 100% for regional wall motion and 100% for ejection fraction. Calculated positive and negative predictive values for regional wall motion were 100% and 63%, respectively. CONCLUSIONS: Although safe, handy, and inexpensive, dipyridamole is not an adequate pharmacological stress test during cardiac catheterisation because of its low sensitivity.

Cardiac Catheterization↗
PubMed1996

Effect of pre-treatment with transdermal glyceryl trinitrate on myocardial ischaemia during coronary angioplasty.

OBJECTIVE: In the light of the reported inconsistent anti-ischaemic and antianginal effects of transdermal glyceryl trinitrate, its efficacy and influence on the effects of intracoronary glyceryl trinitrate were examined during coronary angioplasty, which provides a model of controlled, reversible ischaemia. DESIGN: Double blind, randomised study of the effect of transdermal and intracoronary glyceryl trinitrate on ischaemia during coronary angioplasty. PATIENTS: 40 patients with isolated severe stenosis of the left anterior descending coronary artery. INTERVENTIONS: Patients were randomised (double blind) to transdermal glyceryl trinitrate (10 mg per day) and placebo, starting four to six hours before angioplasty. After 4 one-minute balloon inflations intracoronary glyceryl trinitrate was injected (0.2 mg) and then 4 further one-minute inflations were performed. MAIN OUTCOME MEASURES: The time to angina and the time to > 0.2 mV ST shift on surface electrocardiogram (ECG) or intracoronary ECG during the individual inflations. RESULTS: These times did not significantly differ during initial inflations between transdermal glyceryl trinitrate (27 (11), 25 (9), and 19 (9) s, respectively) and placebo (34 (11), 30 (8), and 21 (7) s. After intracoronary glyceryl trinitrate, they were significantly prolonged compared with the initial values, without differences between patients with transdermal glyceryl trinitrate (37 (10), 30 (8), and 23 (8) s, respectively) or placebo (39 (15), 36 (11), and 28 (12) s). Ischaemic preconditioning was not seen. CONCLUSIONS: Transdermal glyceryl trinitrate (10 mg per day), unlike intracoronary glyceryl trinitrate, did not alleviate the myocardial ischaemia produced by balloon inflation during coronary angioplasty.

Administration, Cutaneous↗
PubMed1996

Low-dose thrombolysis for thrombosed prosthetic heart valve.

This report describes two cases of successful fibrinolysis of thrombosed tricuspid and mitral valve prostheses (Carbomedics; Austin, Texas) with low-dose urokinase therapy corresponding to only one third of the dose usually recommended.

Heart Valve Prosthesis↗
PubMed1996

Cardioprotection in patients undergoing chemo- and/or radiotherapy for neoplastic disease. A pilot study.

OBJECTIVES: To assess the cardioprotective efficiency of an antioxidant regimen (vitamins E, C and N-acetylcysteine) in patients receiving high dose chemo- and/or radiotherapy for malignant disease. METHODS: Prospective, placebo controlled, randomized and double blinded pilot study involving 13 patients receiving chemotherapy and 12 patients receiving radiotherapy. RESULTS: In patients receiving antioxidants, left ventricular ejection fraction did not change (63 +/- 4% to 63 +/- 4%). In the placebo group, ejection fraction changed from 67 +/- 6% to 61 +/- 4% (p = 0.03). No patient in the antioxidant group and 6/13 (46%) patients in the placebo group showed a fall of > 10% in the left ventricular ejection fraction. In the chemotherapy group, the left ventricular ejection fraction changed from 62% (+/- 2) to 63% (+/- 2) in the patients treated with antioxidants (ns) and from 63% (+/- 5) to 61% (+/- 5) in patients treated with placebo (ns). No patient showed a significant fall in ejection fraction in the antioxidant group, whereas 2/7 (29%) in the placebo group showed a reduction > or = 10%. In the radiotherapy group, left ventricular ejection fraction did not change ¿64% (+/- 6) to 64% (+/- 5)¿ in patients treated with antioxidants (ns) and changed from 70% (+/- 8) to 60% (+/- 4) in patients treated with placebo (p = 0.008). No patient in the antioxidant group, but 4/6 (66%) patients in the placebo group showed a fall of > or = 10% in ejection fraction. CONCLUSION: The small number of patients in the study precludes a definitive statement. The preliminary results however suggest efficient cardioprotection by this nontoxic and inexpensive antioxidant combination, so larger studies are warranted for confirmation.

Acetylcysteine↗
PubMed1996

Regional wall motion changes with dobutamine as a pharmacological stress test during cardiac catheterization in patients with significant coronary artery disease.

BACKGROUND: Preliminary study to test the feasibility of pharmacological stress testing during cardiac catheterization, thus combining anatomical and functional information. PATIENTS AND METHODS: 21 consecutive patients with known or suspected coronary artery disease, referred for diagnostic catheterization. Biplane ventriculography was performed before and during dobutamine infusion. The patients were subdivided into 3 groups: Group I (n = 11, 52%) with at least one territory supplied by a significantly stenosed coronary artery and showing normal resting regional wall motion. Group II (n = 6, 29%) patients in whom the affected vessel(s) supplied exclusively a territory with regional wall motion abnormalities at rest. Group III (n = 4, 19%) had no significant coronary artery disease and served as control. RESULTS: In group I, 9/11 (82%) patients and in group II, 3/6 (50%) patients showed either ischemia or viability reactions or both after dobutamine stress. Overall, substantial functional information was gathered in 12/17 patients (71%). Control patients showed no worsening of regional wall motion under dobutamine. Neither global left ventricular ejection fraction nor left ventricular end diastolic pressure were as accurate in detecting ischemia as regional wall motion analysis. In patients who had only ischemia and no viability reaction as judged by regional wall motion analysis, ejection fraction fell significantly in 4/6 (67%) patients; end diastolic pressure on the other hand rose significantly in 3/6 (50%). CONCLUSIONS: Dobutamine stress testing performed during cardiac catheterization is convenient, feasible and safe and yields clinically useful information in a high percentage (71%) of patients with significant coronary artery disease. Further experience is needed to evaluate the sensitivity, specificity and predictive value of this new approach.

Cardiac Catheterization↗
PubMed1996

Percutaneous Transluminal Coronary Angioplasty Through 5 French Diagnostic Catheters.

In 130 patients, coronary angioplasty (PTCA) with fixed wire balloons through 5 French (F) diagnostic catheters was performed immediately following diagnostic coronary angiography. Patients with complex lesions or in whom the need for alternative devices was likely such as stents were excluded. A total of 151 lesions were attempted. Primary success with 5F systems was achieved in 92% of lesions. In 7 cases, the 5F system failed to cross the stenosis and a change to a larger guiding catheter was necessary. Of these 7 cases, 6 could be dilated successfully with 6 or 7F systems. In one patient in whom the fixed wire balloon was not able to cross a subtotal stenosis of an obtuse marginal branch through the 5F catheter, a Monorail system through a 6F guiding catheter failed as well. The overall technical success rate was 96%. Cardiac complications occurred in 2% of patients (3 patients with Q-wave myocardial infarction). Two other patients (1.5%) with suboptimal PTCA results underwent bypass surgery. PTCA through small diagnostic catheters is a valid alternative technique in selected patients. It is safe and leads to high success rates. Advantages of this technique include 1) less peripheral and coronary trauma; 2) enhanced patient comfort; 3) economical advantages.

Journal Article↗
PubMed1996

[Primary balloon dilatation in every coronary stenosis?].

The introduction of coronary balloon angioplasty launched interventional cardiology. The first 18 years saw significant technical refinements of the dilatation catheters. Balloon catheters remained the primary instrument for coronary angioplasty in spite of the arrival of various new devices. Only the stent has proved really advantageous. The marked increase of coronary angioplasty procedures worldwide is based on two facts. First, coronary artery disease is being detected increasingly earlier. Second, early states of coronary artery disease are treated invasively more and more often. Today, the majority of coronary angioplasty procedures is performed in patients who would have been treated medically a decade ago. The dominant role of coronary bypass surgery in true triple vessel disease has not been challenged. The tendency to perform coronary angioplasty in early coronary disease can only be justified if the method remains simple or gets even more simple and cost efficient. The increasing frequency of angioplasty procedures done during the diagnostic study is tending in that direction, as does the decreasing diameter of the material used. At present, there is no coronary situation where a new device should be used rather than a balloon catheter. Therefore, simple and complex cases should be attempted with a balloon first. New devices should only be used in case of a failure of the balloon. A frequent failure of balloon dilatation is a menacing dissection for which the stent is the therapy of choice. The need for the remaining new devices is very small (e.g., rotablator or laser for unpassable or uncrackable stenoses) or non existent.

Angioplasty, Balloon, Coronary↗
PubMed1996

[Quality assurance in invasive cardiology: Switzerland].

In Switzerland, since 1985 mortality and morbidity data concerning either diagnostic and therapeutical coronary catheterization have been annually collected and analyzed. All interventional centres of the country (1994: 5 universities, 9 private and 3 public non academic hospitals) delivered their respective data. While there was a marked increase in diagnostic catheterizations (1989: 11'197, 1994: 20'603) and PTCAs (1989: 1'976, 1994: 5'590), the incidence of procedure related myocardial infarctions, emergency coronary artery bypass graftings (CABG) and in-hospital deaths evolved as shown in table 1 (results separated for university and non-university centres). Procedure related myocardial infarction and emergency CABG rates in patients undergoing PTCA have dropped from 2.1% to 0.9% and 3.1% to 1%, respectively, within 5 years. In the same period of time, the incidence of myocardial infarction after PTCA slightly increased from 0.7% to 0.9%. The higher rates of infarction and death in university hospitals do not necessarily mean poor quality of treatment but may reflect a more complex patient population in these centres. Furthermore, as declaring complications tends to be influenced by the concern of a negative impact on referrals, our data probably underestimate the true complications rates. For future surveys we consider anonymous data presentation and per-sonal audits at the individual centres.

Angioplasty, Balloon, Coronary↗
PubMed1996

[Rendering public health reports in cities and regions--results of a model trial in Brandenburg and North Rhine-Westphalia].

The purpose of health reporting is to give orienting advices for health policy at regional and local level. In fact, there are only few communities and districts engaged in health reporting. A pilot project run in North Rhine-Westphalia and Brandenburg tried to fill the gap by developing and examining methods and procedures of producing regional health reports. Therefore a system of report topics was drawn up which allowed gradual processing and division of work between the five participating local health departments. Each health department chose three topics to be dealt with during a two-year phase of practice. Those working on the project individually advised and supported planning and realisation of the reports. The "health reporter" in the local health department should organize the production of the reports together with experts. Because of lack of experience or fear of not being accepted in an organizing role this person mainly functioned as author of the report. This had a negative effect on quality and continuity of the work. It can however be regarded as a success of the pilote scheme that this development will be continued in form of a broader planned project supported by the Ministry of Employment, Health and Social Affaires of Northrhine-Westphalia.

Adult↗
PubMed1995

Metal uptake of recombinant cambialistic superoxide dismutase from Propionibacterium shermanii is affected by growth conditions of host Escherichia coli cells.

We constructed the complete nucleotide sequence coding for the cambialistic superoxide dismutase from Propionibacterium shermanii by ligation of a synthetic linker to a polymerase chain reaction amplification product obtained using degenerate primers. We set up an expression system yielding large amounts of recombinant superoxide dismutase in the cytoplasm of Escherichia coli and purified the enzyme from cells grown in a complex medium. The physicochemical properties of the recombinant enzyme were identical to those of the natural protein. Under anaerobic conditions the enzyme produced in an iron-supplemented medium incorporated iron as metal cofactor, while the enzyme purified from cells grown under aerobic conditions contained a variable amount of iron and manganese depending on metal availability. Functional equivalence of the two metals in this superoxide dismutase variant was indicated by independence of enzyme activity from Fe/Mn ratio.

Amino Acid Sequence↗
PubMed1995

Induction of oxidative stress by okadaic acid is required for activation of transcription factor NF-kappa B.

The widely used phosphatase 1 and 2A inhibitor okadaic acid is one of the many stimuli activating transcription factor NF-kappa B in cultured cells. Phosphorylation of I kappa B-alpha, one of NF-kappa B's inhibitory subunits, is a prerequisite for I kappa B degradation and the subsequent liberation of transcriptionally active NF-kappa B. This observation suggested that the phosphorylation status of I kappa B is influenced by an okadaic acid-sensitive phosphatase. In this study, we provide evidence that the effect of okadaic acid on NF-kappa B activation is indirect and dependent on the production of reactive oxygen intermediates rather than the inhibition of an I kappa B-alpha phosphatase. Okadaic acid was found to be a strong inducer of cellular H2O2 and superoxide production in two distinct cell lines. The structurally unrelated phosphatase inhibitor calyculin A also induced oxidative stress. The delayed onset of reactive oxygen production in response to okadaic acid correlated with the delayed activation of NF-kappa B. Moreover, NF-kappa B induction was optimal at the same okadaic acid concentration that caused optimal H2O2 production. Both reactive oxygen intermediates production and NF-kappa B activation were inhibited by the antioxidant pyrrolidine dithiocarbamate and 8-(diethylamino)octyl-3,4,5-trimethyoxybenzoate, a Ca2+ chelator. Future experiments using phosphatase inhibitors in intact cells must consider that the compounds can act as strong inducers of oxidative stress, which provides one explanation for their tumor-promoting activity.

Antioxidants↗
PubMed1995

[Mitral valvuloplasty using the Inoue balloon].

Percutaneous mitral balloon valvuloplasty (PMBV) is an accepted alternative treatment to open and closed mitral commissurotomy or mitral valvular replacement. The Inoue technique has become standard in most centers. In our first 24 percutaneous balloon mitral valvuloplasties by the Inoue technique, 23 procedures were technically successful. The mean age of the patients was 53 (24-75) years. There were 22 women. Four patients had a history of closed mitral commissurotomy, one of previous mitral balloon valvuloplasty, and one of aortic metallic valve replacement. The mean echocardiographic mitral Wilkins score was 7.3 (range 4-13). PMBV resulted in significant improvement of hemodynamic values. The mean mitral pressure gradient fell from 12 +/- 5 to 5 +/- 3 mm Hg (p = 0.0001) and the cardiac index increased from 2.7 +/- 0.7 to 3.0 +/- 0.8 l/min/m2. The valve area by the Gorlin formula increased from 1.2 +/- 0.3 to 2.1 +/- 0.6 cm2 (p = 0.0001). Doppler and planimetric echocardiography data were in keeping with hemodynamic data. Mitral valve regurgitation increased by more than 1 grade in 3 patients, 2 of whom subsequently underwent valve replacement. No tamponade occurred with the Inoue technique. There was 1 fatal outcome following tamponade and emergency heart surgery after mitral valvuloplasty with a Trefoil balloon employed in a subsequent intervention due to impossibility of placing the Inoue balloon. Left-to-right shunting at the atrial level after the intervention was not significant in any patient. 21 patients (88%) had improvement in their functional class. One of the patients with unchanged functional class had late onset of severe mitral regurgitation, another had a technical failure with the Inoue technique, and in 1 patient with calcified valve leaflets significant mitral stenosis persisted. At 3 to 15 months follow-up echocardiography was performed in 19 patients: mitral valve areas had not changed significantly compared to post-interventional values. One patient had a new mitral regurgitation compared with the situation immediately after PMBV. Mitral balloon valvuloplasty by the Inoue technique is an effective treatment with low risk in patients with symptomatic mitral stenosis.

Adult↗
PubMed1995

[Management of patients with carotid stenosis and coronary heart disease].

Coronary and carotid atherosclerosis are often coexistent in the same patient. Therefore, patients presenting with carotid stenosis should be screened for coronary heart disease and vice versa. Patients with significant asymptomatic or symptomatic carotid stenosis have an elevated perioperative risk of cerebral ischemic attacks during operations with extracorporeal circulation and of myocardial infarction during carotid endarterectomy. The operations should be performed simultaneously, with carotid endarterectomy being done before sternotomy. This yields mortality and morbidity rates comparable with those for isolated operations on extracorporeal circulation. Medical therapy for such patients consists of platelet inhibitors with adequate cardiac medication.

Adult↗
PubMed1995

[Cardioprotection in chemo- and radiotherapy for malignant diseases--an echocardiographic pilot study].

AIM: Pilot study, examining the cardioprotective effect of an antioxidant regimen in patients with malignancies receiving high dose chemo- or radiotherapy. PATIENTS AND METHODS: 14 patients with chemotherapy and 10 patients with radiotherapy were randomized in a double-blind fashion (placebo versus vitamin E and C and N-acetylcysteine). Systolic and diastolic echocardiographic parameters were determined before and within three weeks of treatment completion. RESULTS: Left ventricular ejection fraction fell significantly in patients receiving placebo (radiotherapy: 67 +/- 6 to 56 +/- 2%, p = 0.008, chemotherapy: 67 +/- 7 to 60 +/- 8%, p = 0.05). Patients on antioxidants showed no significant fall in EF (radiotherapy: 63 +/- 8 to 61 +/- 7%, chemotherapy: 67 +/- 5 to 64 +/- 6%). CONCLUSION: The small number of patients in the study precludes a definitive statement. The preliminary results, however, suggest efficient cardioprotection by this cheap and safe antioxidant combination, so that larger studies are warranted for confirmation.

Acetylcysteine↗
PubMed1995

Kinetic and spectroscopic studies on a superoxide dismutase from Propionibacterium shermanii that is active with iron or manganese: pH-dependence.

Kinetic studies were performed on the superoxide dismutases isolated from the anaerobic bacterium Propionibacterium shermanii as active enzymes with either iron or manganese, which were naturally incorporated into the same molecule depending on the metal supply. Both the Fe- and Mn- forms showed decreasing activity with increasing pH. This suggests the protonation of some groups near the metal, possibly a metal-bound water molecule. Thus the kinetic behaviour of this superoxide dismutase is much more dependent on the protein structure than on the metal incorporated into the active site. The secondary structures of both forms were not influenced by variations in pH, whereas the EPR spectra of the Fe-superoxide dismutase changed as a function of pH. The EPR spectra apparently consist of two overlapping species. Steady-state experiments proved that all iron-containing species show catalytic activity, but the species predominating in the alkaline pH range displays a lower reaction rate. The Michaelis constant and maximal turnover number for the Fe-superoxide dismutase were determined polarographically as Km = 0.54 mmol/l and Vmax. = 2000 mol.s-1 at pH 9.5. These data indicate that, in anaerobic bacteria under physiological conditions, the superoxide dismutase is not saturable with O2-. and the catalytic activity is similar to that of metal-specific Fe- or Mn-superoxide dismutases from aerobic organisms.

Animals↗
PubMed1995

[Adult patients with congenital heart diseases: Berne statistics].

Data of the 272 adult patients with congenital heart disease followed up in our department are analyzed. We emphasize the lack of reliable statistical surveys of this group of patients at the present time. The need for better intra- and interdisciplinary cooperation, specially between referring physicians and tertiary centers, is stressed.

Adult↗