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Biomedical subjects

B Meier

Publications and source records attributed to B Meier.

At least 127 records · Page 7Linked to original sources
PubMed1999

The history of angioplasty therapy for acute myocardial infarction: buried alive but still kicking?

Angioplasty therapy for acute myocardial infarction (direct or primary coronary angioplasty) has been a hot issue of the medical literature since 1982. It was first presented as a rescue therapy in the case of failed intracoronary thrombolysis. Later it was described as a useful complement to thrombolysis before it emerged as a formidable alternative. For a number of years in the late 1980s, the advent of clot-specific intravenous thrombolysis swayed the spotlight from direct angioplasty on to the non-invasive active drug treatment. This was reversed by the appearance of several randomized studies demonstrating superiority of angioplasty in 1992. Later studies have put this advantage of angioplasty over thrombolysis in perspective again. It was found that the superior results of the randomized studies on selected patients could not be reproduced in everyday cases. Nonetheless, a small but significant advantage of primary angioplasty remains when all available literature is scrutinized carefully. Even if the results in terms of mortality and acute events during the initial hospital stay are quite comparable for thrombolysis and primary angioplasty, the latter removes the culprit clot, treats the underlying lesion, and informs about the general state of the coronary vasculature and the myocardium with unsurpassed details. Moreover, most patients with intravenous thrombolysis will undergo cardiac catheterization within the first year after their infarction. Thus, the facts that the initial savings of foregoing cardiac catheterization is lost and the cost of the thrombolytic drug can be spared with primary angioplasty may tilt the scale in favour of primary catheter intervention. As direct angioplasty establishes patency earlier and more completely than thrombolysis, a slightly better hospital course and markedly better long-term course with improved longevity, myocardial function, and fewer cardiac events can be achieved. This is not necessarily associated with a higher investment, because the initial surplus in cost of primary angioplasty tends to revert into savings over time. All patients amenable to direct angioplasty within 30-60 min after initial diagnosis should be offered the procedure. In the remaining cases, thrombolysis is the preferred treatment. The role of primary angioplasty is the more important the larger the infarction. However, in small infarctions but also in protracted cardiogenic shock it may be wasted, but so is any other aggressive treatment.

Angioplasty, Balloon, Coronary↗
PubMed1998

Hemodynamic and coronary effects of the endothelin antagonist bosentan in patients with coronary artery disease.

BACKGROUND: Endothelin is a potent endothelium-derived vasoconstrictor peptide with proliferative properties. Elevated levels of the peptide occur in coronary artery disease; however, its pathophysiological role as a regulator of coronary tone and structure is uncertain. Endothelin-receptor antagonists are specific tools to clarify this issue and might be useful in the treatment of coronary artery disease. METHODS AND RESULTS: In a double-blind, placebo-controlled randomized study, we investigated the effects of the ETA/ETB endothelin-receptor antagonist bosentan or placebo on systemic and coronary hemodynamics in 28 patients with angiographically documented stable coronary artery disease by quantitative coronary angiography and an intracoronary Doppler guidewire. Bosentan 200 mg IV decreased systolic blood pressure (P<0. 05), whereas heart rate increased slightly (P<0.05). Coronary diameter increased, particularly in vessels with no or mild angiographic changes (P<0.01). Glycerol trinitrate did not further dilate these segments, whereas coronary diameter increased significantly after nitrate in the placebo group. The increase in coronary diameter after bosentan correlated inversely with plasma LDL-cholesterol levels (P<0.01) in both stenotic and angiographically normal coronary segments. Coronary flow velocity did not change. Bosentan was well tolerated. CONCLUSIONS: Endogenous endothelin exerts a vasoconstrictor tone in epicardial coronary arteries of patients with coronary artery disease, as evidenced by the vasodilation exerted by the combined ETA/ETB endothelin-receptor antagonist bosentan under acute conditions. Bosentan can safely be given to these patients. Hence, further long-term studies are necessary to determine the therapeutic potential of endothelin-receptor antagonists in patients with coronary artery disease.

Antihypertensive Agents↗
PubMed1998

[Secondary prevention of ischemic heart disease after coronary revascularization].

This study was aimed to assess the compliance with policies for secondary prevention of coronary heart disease (CHD) one year after coronary artery revascularization with special attention to the management of hyperlipidemia. One year after coronary revascularization during the year 1994, patients were contacted by letter to determine the modification of their risk factors, the treatment patterns for hypercholesterolemia and to have their plasma lipid level and blood pressure measured. Of the 245 consecutive patients contacted (110 after coronary artery bypass grafting, and 135 after percutaneous transluminal coronary angioplasty), 186 (76%) provided the information required for further analysis. Excluding the patients older than 65 years, only 29 out of 97 patients (30%) with a total cholesterol of more than 5.2 mmol/l, and only 20 out of 52 patients (38%) with a total cholesterol of more than 6.2 mmol/l were receiving lipid lowering therapy 1 year after coronary artery revascularization. In contrast, 97% (n = 180) of the entire population studied were taking antiplatelet drugs and/or coumadine. Participation in an in-house rehabilitation program yielded a positive influence on smoking, but not on treatment of hypercholesterolemia. In conclusion, only a small proportion of patients with documented CHD and hypercholesterolemia were being treated for their lipid disorder 1 year after coronary artery revascularization. In contrast, the great majority of patients received antiplatelet and/or coumadine therapy: These results indicate that the compliance with published treatment guidelines for hyperlipidemia in patients with CHD is still highly inadequate, irrespective of the participation in a rehabilitation program.

Aged↗
PubMed1998

[Pathophysiology of coronary collateral circulation in the human].

The functional relevance of coronary collaterals in humans has yet to be fully explored. Several studies demonstrated a protective role of collaterals in patients with coronary artery disease. On the other hand, negative aspects of well-developed coronary collaterals have been reported, e.g. a higher rate of restenosis following coronary angioplasty, or a redistribution of blood via collaterals away from the myocardial area in need towards normally perfused areas (coronary steal). In the past, the coronary collateral circulation has been assessed only qualitatively, using visual angiographic or nuclear imaging methods. With the recent advent of intracoronary Doppler and pressure-transducers, quantitative assessment of functional parameters of the coronary circulation has become feasible. This article reviews ongoing research in the field of coronary collaterals in humans, concerning their exact determination, the positive and negative aspects of their structure as well as their functional aspects.

Angioplasty, Balloon, Coronary↗
PubMed1998

Initial results of laser-based percutaneous myocardial revascularization for angina pectoris.

Results of a 30-patient pilot study of a recently developed percutaneous myocardial revascularization approach are described. The feasibility and positive safety profile of percutaneous myocardial revascularization are clearly demonstrated, with no mortality associated with the treatment or in the immediate post-treatment period and an incidence of only 1 major complication.

Aged↗
PubMed1998

[Acute myocardial infarct in Switzerland: results from the PIMICS Heart Infarct Register. PIMICS Project (Prospective Ischemia Myocardial Infarction Captopril Survey)].

The aim of the PIMICS project was to create, for the first time in Switzerland, a registry of data concerning epidemiology and therapy in patients hospitalised for acute myocardial infarction covering all regions of the country. During 1995/96 73 Swiss hospitals of all categories took part in the PIMICS project. The ratio between males and females in the 3877 registered patients was 2.6:1 (2791 men vs. 1086 women). Female patients were significantly older than males (70.4 +/- 12.0 years vs. 63.4 +/- 12.6 years; p < 0.0001). The prevalence of risk factors differed between men and women: significantly more women had hypertension or diabetes, whereas smoking was more prevalent in males. The median delay between onset of symptoms and arrival at the hospital was 5.5 hours. Thrombolysis and primary angioplasty were more frequently performed in men (40.4% vs. 31.2% in women, p < 0.0001, and 5.7% in men vs. 3.5% in women, p = 0.005 respectively). During the acute phase males were treated more frequently with betablockers. The overall in-hospital mortality was 9.1%. It was significantly higher in female patients (13.5% vs. 7.4% in men; p < 0.0001) and in patients with reinfarction (14.5% vs. 7.1%; p < 0.0001). The mean hospital stay was 12.6 +/- 5.3 days. Only 7.7% of all patients with acute myocardial infarction were discharged within 6 days. At discharge, 51.7% were treated with betablockers and 69.3% with aspirin; 44.8% received ACE-inhibitors and only 13.8% lipid-lowering drugs. Follow-up measures such as coronary angiography and/or angioplasty or bypass surgery were performed significantly more often in males (45.0% vs. 32.9%; p < 0.0001). Likewise, men were more frequently assigned to a rehabilitation program than women (38.2% vs. 32.9%; p = 0.0004). The pre-hospital delay in patients with acute myocardial infarction remains too long. Primary and secondary prevention should be intensified in high risk groups, particularly in females. Thrombolysis and primary angioplasty as mainstays of treatment in acute myocardial infarction are generally used too sparingly, especially in women. With such measures the hospital stay could be shortened further.

Adult↗
PubMed1998

[High altitude stay and air travel in coronary heart disease].

Acute exposure to high altitude produces hypoxia-associated stimulation of the sympathetic nervous system. This response is further enhanced by physical activity and induces an increase in heart rate and blood pressure. Consequently, cardiac work, myocardial oxygen consumption, and coronary blood flow are also increased. During the first 4 days of acute exposure to moderate or high altitude, coronary patients are at greatest risk of untoward events. Gradual ascent, early limitation of activity to a lower level than tolerated at low altitude, pre-ascent physical conditioning and rigorous blood pressure control should all help to minimise the cardiac risk. At altitudes of 2500 to 3000 m or lower, an asymptomatic coronary patient with good exercise tolerance, without exercise induced signs or symptoms of ischemia, and with an ejection fraction of the left ventricle > 50%, is at very low risk. However, several days' acclimatization before high-level activity at moderate or high altitude is recommended. High risk coronary patients should be investigated more carefully and precautionary measures should be more stringent. Left and right cardiac function and pulmonary artery pressure are the most helpful parameters for evaluation and counselling of patients with non-ischemic heart disease who plan to ascend to moderate or high altitudes. When advising patients who intend to fly as passengers in commercial aircraft, it is important to know that in-flight atmospheric pressure conditions in commercial jet aircraft approach altitude equivalents of 1500 to 2400 m. Propeller-driven planes are rarely pressurized but usually fly at altitudes below 3300 m. Relatively strict contraindications for air travel by coronary patients are uncomplicated myocardial infarction within the last 2 weeks, complicated myocardial infarction within the last 6 weeks, unstable angina, thoracic surgery within the last 3 weeks, and poorly controlled congestive heart failure, arrhythmia, or hypertension.

Aircraft↗
PubMed1998

Midazolam premedication improves tolerance of transesophageal echocardiography.

Patient premedication for transesophageal echocardiography (TEE) is still under debate, especially the use of sedatives. We performed a double-blind, placebo-controlled study to clarify the efficacy of low-dose intravenous midazolam as premedication for TEE. Placebo or midazolam (< or =50 kg, 2.0 mg intravenously; 50 to 80 kg, 2.5 mg; and > or =80 kg, 3.0 mg intravenously) was given in addition to topical anesthesia to 200 consecutive in- and outpatients. Blood pressure, heart rate, and oxygen saturation were monitored. Patients were interviewed immediately, and 2 to 10 days after TEE. Sixteen patients received an additional dose of midazolam, and in 12 follow-up was incomplete. Patients taking midazolam reported less gag reflex at probe introduction and during TEE, as did the examiners (p < 0.05 to 0.0001). Probe manipulations were found to produce less discomfort after midazolam administration (p < 0.005). Midazolam patients experienced less dyspnea (p < 0.01) despite a minimal decrease in oxygen saturation of 2% (p < 0.0001). The following day patients taking midazolam reported less sore throats, and painful swallowing was less frequent (p < 0.01 to 0.001). Systolic blood pressure decreased slightly in the midazolam group (132 +/- 24 to 121 +/- 20 mm Hg, p < 0.0001). The rate of minor complications showed no difference. Thus, TEE probe introduction and manipulation was tolerated better after low-dose midazolam premedication, and patients experienced less pharyngeal discomfort the day after. Midazolam was well tolerated and the complication rate did not increase. Thus low-dose, short-acting benzodiazepine premedication improves patient comfort during and after TEE and generous use can be recommended.

Anesthetics, Intravenous↗
PubMed1998

pH-dependent inhibition by azide and fluoride of the iron superoxide dismutase from Propionibacterium shermanii.

The iron-containing superoxide dismutase from Propionibacterium shermanii shows, in contrast with other iron superoxide dismutases, only a minor inhibition by azide or fluoride (10-100 mM) of up to 23% at pH 7.8. The activity of the protein with Mn bound to the active site was not diminished under the same conditions. The binding constant between azide and the Fe3+ ion was determined as approx. 2 mM and for fluoride approx. 2.3 mM; they are so far comparable to those known for other iron superoxide dismutases. This seems to be a discrepancy because all other iron superoxide dismutases so far known are described as being inhibited by 50-70% by 10 mM azide. However, towards lower pH there was a drastically increased inhibition by both anions. At pH 6.8 about 80% inhibition was exhibited by azide or fluoride at a concentration of 10 mM or higher. In contrast, on increasing the pH, azide or fluoride still bound to the Fe3+ at the active site but their inhibition capacity decreased. This observation implies that both anions bind to the metal at a position that is empty at low pH, whereas at higher pH water or a negatively charged hydroxyl anion is bound. It is likely that the superoxide anion binds to the same position and has to replace the sixth ligand, leading to a diminished catalytic activity of the superoxide dismutase owing to steric and/or electrostatic inhibition of the ligand.

Azides↗
PubMed1998

Petasites hybridus: a tool for interdisciplinary research in phytotherapy.

The 3rd Petasites gathering took place in Romanshorn, Switzerland on March 29, 1996 and gave 16 European scientists the opportunity to transmit their latest considerable discoveries to interested researchers working in different scientific disciplines such as pharmacognosy, botany, chemistry, pharmacology, medicine or clinical pharmacy. The newest findings on Petasites hybridus as a significant plant drug showed very promising aspects of therapeutic utility. Great progress has been made in chemical analytical methods and the determination of pharmacological activities. Substantial advances have also occurred in the production of bioassay procedures and plant materials, particularly utilizing cell- and tissue-culture techniques.

Animals↗