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Biomedical subjects

B Meier

Publications and source records attributed to B Meier.

At least 163 records · Page 9Linked to original sources
PubMed1998

[Local vascular complications after heart catheterization].

Vascular complications such as haematoma and pseudoaneurysm are a significant problem in patients undergoing arterial catheterization. Ultrasound-guided compression of the pseudoaneurysm is a non-invasive and efficient therapy. We describe two patients with rare complications. A 59-year old man died of multiple pulmonary embolism after diagnostic cardiac catheterization. A 71-year old female patient developed a deep inguinal skin necrosis after repeated local compression of a pseudoaneurysm formed after therapeutic catheterization.

Aged↗
PubMed1998

Interventional cardiology in perspective: impact on cardiac rehabilitation.

Exponential evolution of percutaneous, catheter-based revascularization has modified traditional premises of cardiac rehabilitation. With increasing numbers of percutaneous transluminal angioplasty (PTCA) procedures relative to coronary artery bypass grafting interventions, the need for in-patient rehabilitation is declining; on the other hand, the need for life-style counselling within the framework of out-patient rehabilitation is increasing. Risk factor interventions are important to minimize and to retard the progression of the disease. Rehabilitation programmes offer exercise training, stress modification and life style counselling to reduce cardiovascular risk factors and to increase exercise capability. Since costs of out-patient rehabilitation seem to be lower than those of in-patient rehabilitation, a case may be made in favour of directing limited funds to additional interventions and to saving money by replacing in-patient rehabilitation with outpatient programmes after PTCA. The budget-holder has to make the choice.

Angioplasty, Balloon, Coronary↗
PubMed1998

[The Magnum wire for the angioplasty of coronary occlusions and stenoses].

The "Magnum wire" is a stiff shaft, blunt tip wire constructed for recanalization of total coronary occlusions. Smaller series have demonstrated superior qualities if compared to conventional wires. The purpose of this study was to analyze its efficacy in total and nontotal lesions in a large number of consecutive procedures. A database analysis identified the use of the Magnum wire in 569 procedures from October 1992 to February 1995, which accounted for 26% of all angioplasties during the time period at our Institution. There were 347 total occlusions and 222 nontotal occlusions. Technical success was achieved in 69% of total occlusions and 90% of subtotal occlusions. Procedural success was recorded in 58 and 75%, respectively. Stents were implanted in 29 patients with total occlusion (8%) and 19 patients with nontotal lesions (9%). Acute occlusion of the treated lesion occurred in 4.5% of patients with nontotal lesion and 1.5% of the patients with total occlusion. In conclusion, the Magnum wire is an efficient tool for angioplasty of total occlusions and severe nonocclusive stenoses. In light of the complexity of the attempted lesions, achieved success rates were remarkable.

Adult↗
PubMed1997

Direct intracoronary evidence of collateral steal in humans.

BACKGROUND: Coronary steal is defined as a fall in blood flow toward a certain vascular region in favor of another area during arteriolar vasodilatation, ie, a coronary flow velocity reserve (CFVR) <1. The purpose of this study was to determine the frequency of steal in patients with a wide range of collateral supply to a vascular area of interest and to assess whether steal is associated with the amount of collateral flow. METHODS AND RESULTS: One hundred patients 57+/-9 years old with a coronary artery stenosis to be dilated were examined with intracoronary (IC) Doppler guidewires. IC adenosine-induced CFVR<1 obtained distal to the stenosis was defined as steal. An index for collateral flow was determined by positioning the Doppler guidewire in the collateral-dependent vessel distal to the stenosis and measuring the flow velocity time integral during (Vi(occl), cm) and after (Vi(ø-occl)) balloon occlusion. Vi(occl)/Vi(ø-occl) was determined without and with intravenous adenosine (140 microg x kg(-1) x min(-1)). Coronary steal occurred in 10 of 100 patients. Patients with steal showed superior collaterals compared with those without steal: Vi(occl)/Vi(ø-occl)=0.65+/-0.24 in patients with steal versus 0.29+/-0.18 in those without steal (P=.0001). In all patients with steal, there was a reduction in collateral flow during intravenous adenosine-induced hyperemia, whereas in the majority (70%) of patients without steal, collateral flow increased or remained unchanged during hyperemia. CONCLUSIONS: Coronary steal assessed by intracoronary Doppler flow velocity measurements occurs in 10% of patients with a wide range of coronary collaterals to the vascular area from which blood flow is redistributed. There is a direct association between the presence of steal away from and the amount of collateral flow toward the region under investigation. Collateral flow to the vascular region studied decreases during adenosine-induced hyperemia, which indicates a mechanism of steal via the extensive collaterals.

Aged↗
PubMed1997

[The first 20 years of coronary angioplasty: retrospective and perspectives].

The first coronary angioplasty (PTCA) procedure performed by Grüntzig in Zurich in 1977 was not the beginning but the breakthrough in interventional cardiology. PTCA is today the most frequent of the major interventions in medicine and constitutes an important economic factor. At first the development of PTCA was slow because many European countries postponed invasive assessment of coronary artery disease until the patient was refractory to a combination of drugs. Thus, the early forms of coronary artery disease, optimal for PTCA, were rarely found among the coronary angiograms performed. In the US, facilities for coronary angiography were already expanding in the seventies. They provided the ideal background for PTCA to thrive. Together with Andreas Grüntzig, PTCA moved to the New World in late 1980. Only very recently, the Old World and the Orient have caught up with the US and are now about to assume a leading role. In spite of untiring endeavors, the angioplasty balloon has not been replaced by more sophisticated systems. Only the coronary stent has proved invaluable as a complement to the balloon. After preliminary use in peripheral vessels, the first coronary stent was implanted by Puel in Toulouse on March 28, 1986. In the meantime, the stent has grown to become an integral part of PTCA in about half the cases. Indications for PTCA have not changed significantly since its inception. Success and complication rates, however, have significantly improved. The method is still best applied to single vessel disease. In double or triple vessel disease, it may be preferable to bypass surgery or medical treatment in selected cases where not all main vessels are affected and the total number of lesions does not exceed 3-4. The risk of an abrupt vessel closure during or immediately after PTCA has decreased over time to about 2% currently compared with 7% before the use of stents. Yet it continues to be a hazard to be taken seriously. The risk of recurrence has also diminished in the era of stents but still amounts to 20-40% depending on the situation. Switzerland occupies an important position in Europe today concerning the use of PTCA per head of population. It is in a group with Belgium, France, and the Netherlands running up to the leader, Germany. Since 1993, there have been more PTCA procedures than coronary bypass operations in Switzerland. PTCA is performed today at 5 university hospitals, 9 additional public hospitals, and 9 private clinics. The majority of the procedures are done during the diagnostic study. The total number of coronary bypass operations has continued to increase slightly in spite of PTCA. This documents the fact that true triple vessel disease is still a domain for surgery and that the indication threshold has been shifted to the elderly patient. Therefore, the total need for revascularization procedures has drastically increased. Further growth of PTCA can be predicted unless political measures, such as rationing, reduced credentialing, or drastic cuts in reimbursement are introduced. The recently developed minimally invasive direct coronary artery bypass (MIDCAB) surgery is likely to compete with conventional bypass surgery as much as with PTCA. Its final role remains to be defined. As a side benefit it represents a means of quality control, uniting surgeons and interventional cardiologists in case discussions again with increasing frequency.

Angioplasty, Balloon, Coronary↗
PubMed1997

[Non-surgical closure of type-II atrial-septal defect and patent foramen ovale].

In the past the standard therapy for significant atrial septal defect was surgical closure. In the presence of a patent foramen ovale with otherwise unexplained (cryptogenic) cerebral embolism, the therapy was oral anticoagulation or antiplatelet therapy. Surgery was considered only in the event of recurrence. Percutaneous transcatheter occlusion of atrial septal defect and patent foramen ovale is a new and valuable alternative to surgical closure. This report presents current knowledge and our own experience of nonsurgical closure of atrial septal defects and patent foramen ovale.

Cardiac Surgical Procedures↗
PubMed1997

Effect of Val 73 --> Trp mutation on the reaction of "cambialistic" superoxide dismutase from Propionibacterium shermanii with hydrogen peroxide.

The H2O2 inactivation of the "cambialistic" superoxide dismutases from Propionibacterium shermanii, which is active with either iron or manganese at the active site, has been studied in the native and Val 73 --> Trp mutant enzymes. The wild-type iron-containing form of this enzyme is much more resistant to treatment with H2O2 with respect to the other metal-specific Fe superoxide dismutase isoenzymes. After incubation with high amounts of H2O2 the enzyme maintains more than 40% of the initial activity. The activity of the Val 73 --> Trp mutant drastically decreases to less than 5% of the initial activity after incubation with hydrogen peroxide. Amino acid analysis of the H2O2-treated mutant enzyme evidenced the loss of the Trp 73 residue which is shown to play a critical role in the stabilization of the monomer fold of the enzyme. On the other hand, the manganese-containing wild-type and mutant enzymes were completely resistant toward H2O2 demonstrating the specific role of iron in the inactivation process.

Binding Sites↗
PubMed1997

Magnum wire for percutaneous coronary balloon angioplasty in 800 total chronic occlusions.

The experience in consecutive procedures with 800 recanalization attempts of chronic total coronary occlusions using the Magnum wire was analyzed from a prospectively constituted computerized database. The data confirm that the Magnum wire, generally used as a primary intervention for occlusive angioplasty at our centers, is competitive with conventional systems in this setting.

Angioplasty, Balloon, Coronary↗
PubMed1997

Comparative stability studies on the iron and manganese forms of the cambialistic superoxide dismutase from Propionibacterium shermanii.

The superoxide dismutase of Propionibacterium shermanii shows similar activity with iron and manganese bound at the active site of the protein. On the other hand, the iron form, in comparison to the manganese form, exhibits higher stability towards thermal- and pH-dependent inactivation. Upon inactivation the metal ions are released from the active site. Thus, in comparison to the manganese form, a higher stability of the iron-protein complex might be the triggering reason for this behavior.

Ammonium Sulfate↗
PubMed1997

Magnum wire for angioplasty of total and non-total coronary lesions.

The magnum wire is a stiff-shaft, blunt-tip wire constructed for recanalisation during angioplasty. Smaller series have demonstrated superior qualities compared to conventional wires. The purpose of this study was to analyze its feasibility in a larger number of procedures. A single centre database analysis identified the use of Magnum wire during 443 procedures accounting for 26% of all angioplasties from October 1992 to February 1995. There were 347 total occlusions and 222 non-total lesions. Technical success was 69% in total and 90% in non-total lesions, whereas angiographic success was 58% and 75%, respectively. Stents were successfully implanted in 48 lesions; in 29 (8%) total occlusions and 19 (9%) non-total lesions. The total occlusion-related complication rate was 1.7%. Acute closure occurred in 4.1% of non-total lesions. In conclusion, Magnum wire is a feasible tool for angioplasty of total occlusions and severe stenoses. It is a cheap, simple and safe method for recanalisation.

Adult↗
PubMed1997

[Atrial septum defect and open foramen ovale. Diagnosis, clinical aspects and therapy using a catheter technique].

The purpose of this report is to describe the pathophysiology and clinical symptoms of atrial septal defects with emphasis on right ventricular failure and the risk of paradoxical embolism in the setting of a patent foramen ovale. The diagnosis of both the atrial septal defects and the patent foramen ovale, usually is made by echocardiography. Percutaneous transcatheter occlusion of an atrial septal defect and a patent foramen ovale has gained interest for some years as a treatment alternative to surgical closure. Preliminary results of different devices have been encouraging and the method appears to be a viable alternative to surgical closure.

Atrial Function, Right↗
PubMed1997

[Measurements of intracoronary pressure and blood flow velocity].

Quantitative coronary angiography and new intracoronary imaging devices are not able to provide functional data for the assessment of the severity of coronary artery stenotic lesions. The functional characterization of coronary artery stenosis gives insight into whether it compromises myocardial perfusion under conditions of pharmacologic or physical stress, i.e., whether the stenosis has hemodynamic relevance. The measurement of trans-stenotic pressure gradients and/or post-stenotic blood flow velocities using very recently developed, miniaturized pressure- and Doppler-angioplasty guidewires (1/3 mm in diameter) provides a valuable alternative to traditional, non-invasive means for the functional assessment of coronary artery disease. The most widely employed parameters for the functional characterization of coronary artery stenoses are the ratio between flow velocities during pharmacologically induced hyperemia and at resting conditions (coronary flow velocity reserve), and the pressure-derived fractional flow reserve, i.e., the ratio of mean poststenotic to mean aortic pressure during hyperemia. Furthermore, poststenotic pressure and flow velocity measurements during and after occlusion of stenosis can be used for the quantitative assessment of collateral circulation among different vascular regions.

Angioplasty, Balloon, Coronary↗
PubMed1997

[Use and significance of intravascular ultrasonic imaging].

Intravascular ultrasound (IVUS) imaging of coronary arteries has recently become possible in vivo with the improvements achieved in the miniaturisation of ultrasound transducers. IVUS provides informations complementary to angiography, and is considered as the gold standard for the assessment of lumen size, plaque thickness and plaque distribution. As formerly demonstrated by pathological studies, IVUS also reveals an underestimation of plaque thickness with angiography and an incomplete assessment of the true morphologic distribution of the plaque burden. Among its clinical applications, IVUS can be used to monitor revascularisation procedures, and may provide very accurate measurements of progression or regression of coronary atherosclerosis and of the extent of posttransplant vasculopathy. IVUS was employed successfully to assess and optimize the results of percutaneous transluminal coronary angioplasty. Clinical studies have shown that the risk of restenosis is inversely proportional to the size of the postprocedural lumen. With the guidance of percutaneous transluminal angioplasty by IVUS, balloon size and inflation pressures were increased, and better results were obtained with larger lumen size in comparison to the results of the procedures assessed by angiography alone. These improvements contributed to abandon the anticoagulation after stent implantation in most cases. In spite of the valuable information provided by IVUS, its role in clinical settings should still be defined IVUS prolongs the revascularisation procedure and enhances its costs and risks. Thus, the cost effectiveness of IVUS in its clinical application should be determined by prospective studies.

Angioplasty, Balloon, Coronary↗