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Biomedical subjects

B Meier

Publications and source records attributed to B Meier.

At least 271 records · Page 15Linked to original sources
PubMed1994

Use of half (disarticulated) Palmaz-Schatz stents for thrombus-containing coronary lesions.

Coronary stenoses associated with thrombus can lead to poor angioplasty results and increased procedural complications. Stenting in the presence of thrombus is associated with an increased risk of stent thrombosis. We report eight patients in whom half a Palmaz-Schatz stent was implanted for inadequate angioplasty results owing to thrombus. Stenting resulted in improved angioplasty results; no stent thrombosis occurred.

Angioplasty, Balloon, Coronary↗
PubMed1994

Reactions of hydrogen peroxide with superoxide dismutase from Propionibacterium shermanii--an enzyme which is equally active with iron or manganese--are independent of the prosthetic metal.

Propionibacterium shermanii contains a single constitutive superoxide dismutase (SOD) which is active with either iron or manganese incorporated in the same protein moiety. Copper and cobalt can also be incorporated by the bacteria in the active center of the SOD under conditions of metal deficiency, but in this case the enzyme is enzymatically inactive. In contrast to other bacterial SODs, the Fe-SOD of P. shermanii remains highly resistant to inactivation by hydrogen peroxide, as does Mn-SOD. Both SOD types cannot be distinguished by their inactivation patterns. Incubation with hydrogen peroxide results in a concentration- and time-dependent decrease in tryptophan fluorescence, independent of the metal present in the active center. Moreover, the Fe-SOD shows a time-dependent decrease in spin concentration after addition of hydrogen peroxide, which reflects alterations in the environment of the metal rather than a reduction of Fe3+ to Fe2+. No obvious correlations exist, however, between these effects and the enzymatic activity of the enzyme. The resistance of the SODs from P. shermanii to inactivation by hydrogen peroxide seems to be caused by the fact that a tryptophan residue near the metal-chelating histidine-75--which is present in all Fe-SODs being rapidly inactivated by this agent--is exchanged for valine.

Amino Acid Sequence↗
PubMed1994

Collagen application versus manual compression: a prospective randomized trial for arterial puncture site closure after coronary angioplasty.

OBJECTIVES: This study evaluated the safety and efficacy of a newly developed puncture-sealing device consisting of subcutaneous bovine collagen application designed to facilitate local hemostasis after coronary angioplasty. BACKGROUND: The most common local hemostatic procedure after coronary angioplasty consists of heparin discontinuation and delayed sheath removal followed by mechanical compression at the puncture site. METHODS: Between December 1991 and February 1993, 124 patients undergoing coronary angioplasty with either a 6F guiding catheter followed by a heparin infusion for > 12 h or a 7F or 8F guiding catheter with optional heparin infusion were prospectively randomized to either delayed sheath removal followed by manual compression (n = 62) or sheath removal immediately after angioplasty combined with bovine collagen application for puncture site closure (n = 62). Half of the collagen plugs were delivered using measured and half using estimated skin-artery distance. Clinical and duplex sonographic evaluations of the puncture site were performed 24 h later. RESULTS: No significant difference in the incidence of local hematomas was observed. Major complications were false aneurysm, venous thrombosis and arterial occlusion. The incidence of false aneurysm was the same in both groups (4 [7%] of 62). Venous thrombosis (2%) and arterial occlusion (2%) were each recorded in one patient, both in the collagen application group. CONCLUSIONS: Sheath removal and collagen application with this new vascular hemostasis device used directly after coronary angioplasty are not superior to delayed sheath removal after heparin discontinuation followed by mechanical compression. Arterial collagen sealing with this device in its current form is associated with a small but worrisome risk of arterial occlusion.

Aged↗
PubMed1994

In-hospital monitoring after coronary angioplasty.

At the University Hospital of Geneva there are three postcoronary angioplasty monitoring levels: (A) intensive care unit; (B) optional ECG monitoring (cardiology unit); and (C) no monitoring (other unit). To assess the adequacy of patient monitoring after coronary angioplasty, we studied the clinical outcome of 200 consecutive patients undergoing coronary angioplasty at different monitoring levels. Thirty-nine patients (20%) were in level A. Their outcome was 1 death, 1 emergency bypass operation, and 7 acute myocardial infarcts. Ninety-six patients (48%) were in level B: no major complication, no transfer of monitoring level, and mean hospital stay 2.7 +/- 1.3 days. Sixty-five patients (32%) were in level C: 1 death, 2 elective bypass operations, 6 transfers to level A, and mean hospital stay 5.9 +/- 4.6 days. Electrocardiogram monitoring of 135 patients yielded 23 significant findings (17%), 22 of which occurred in patients with complicated or failed procedure. In the 122 patients with successful coronary angioplasty without angiographic visible local complications and without clinical symptoms at the end of the procedure, no significant arrhythmia or acute myocardial infarction was documented. For this type of patient, ECG monitoring is not a prerequisite after coronary angioplasty. Surveying all patients after coronary angioplasty in the coronary care unit would not significantly reduce complications. Aftercare in a cardiology unit results in a shorter hospital stay.

Adult↗
PubMed1994

[Immediate results of coronary endoprosthesis in threatening or occlusive dissections complicating angioplasty; the Geneva experience].

Between April 1988 and September 1993, 123 patients (average age 60.4 +/- 8.9 years) underwent coronary stenting for threatening or occlusive dissection complicating angioplasty. The anterograde coronary flow was disturbed in 51% of cases (TIMI-0-2). The artery concerned was the left anterior descending in 59% of cases, the right coronary in 28% of cases, the circumflex in 12% and a coronary bypass graft in 1% of cases. Technically, the stenting was successful in 118 cases (98%) and, in 21 cases, complete stenting of the dissection required the insertion of several stents. The minimal coronary diameter after expansion of the stent was 3.1 +/- 0.6 mm. During hospital follow-up, 3 deaths (3%) and 7 Q-wave infarcts were observed. Twenty-eight patients (23%) developed a haemorrhagic complication, including 2 retroperitoneal and 2 intracerebral bleeds. Eight patients (6%) underwent coronary bypass grafting, as an emergency in 4 cases and semi-electively in another 4 cases. One hundred and five patients (89%) survived the intra-hospital period without major complications (death, Q-wave infarction, emergency coronary bypass surgery or severe haemorrhage). Coronary stenting for threatening or occlusive dissection complicating angioplasty seems to be a reasonable solution and a usually definitive one. The frequency of haemorrhagic complications underlines the need for strict clinical and biological surveillance.

Aged↗
PubMed1994

Percutaneous transluminal coronary angioplasty of left main coronary artery.

The present study is a retrospective analysis of 15 percutaneous angioplasty procedures of the left main coronary artery performed in 12 patients (8 males (66%) with a mean age of 64 +/- 12 (range 45-79) years. Twelve dilatations were elective: 8 for unstable angina, 3 for stable angina, and 1 after a recent myocardial infarction. All elective patients were protected with at least 1 patent graft to the distal left coronary artery. Emergency dilatation for evolving myocardial infarction with cardiogenic shock was done in 3 patients. The right coronary artery was dominant in 11 cases. The mean ejection fraction was 49 +/- 18% (range 21-7%). All dilatations were done through the femoral approach. Two dilatations were performed with the "kissing balloon" technique and 2 with the "kissing wire" technique. An intra-aortic balloon counterpulsation was used in 3 cases (21%). In 8 cases (53%), 1 additional coronary artery was dilated in the same session. The technical success rate was 100% and the clinical success rate 73%. For the elective dilatations, the technical success rate was 100% and the clinical success rate 92% (11/12). Four patients died during hospitalisation (27%). The mortality rate was 100% (3/3) for emergency dilatations and 8% (1/12) for elective dilatations (patient with dilatation of 3 vessels and 1 graft in the same session). After a mean follow-up of 25 +/- 28 (rang 1-88) months, the 8 patients discharged from hospital were alive.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

[Mycotic aneurysm of the external iliac artery as a complication of percutaneous transluminal coronary artery dilatation].

Percutaneous coronary interventional procedures exhibit an increased risk of peripheral vascular complications compared with diagnostic coronary angiography. Septic complications affect typically the puncture site. We describe a septic event (staphylococcus aureus) resulting in a mycotic aneurysm of the iliacal artery with embolic gonarthritis after a prolonged percutaneous transluminal coronary angioplasty performed 13 days after diagnostic coronary angiography using the same vascular access. The presumed culprit was the reintroduced dilatator which must have been contaminated. An emergency resection of the aneurysm and implantation of a Gore-Tex crossover bypass had to be performed. With prolonged parenteral and enteral antibiotic treatment the infection was controlled. We discuss risk factors for septic complications after coronary interventions and possible preventive measures.

Adult↗
PubMed1993

[Coronary angioplasty in octogenarians].

Coronary balloon angioplasty was performed on 33 lesions during 28 procedures in 23 octogenarians (median age 83, range 80 to 87 years) between January 1989 and December 1991. 96% of the patients had grade III-IV angina pectoris. The median left ventricular ejection fraction was 64% (range: 38-85%). Single vessel coronary artery disease was present in 43% and multivessel coronary artery disease in 57%. Angioplasty was performed on 1 vessel in 85% of the procedures and on 2 vessels in 15%. Primary angiographic success was 97% for 33 attempted lesions with one failure to recanalize an old occlusion. One patient underwent emergency intracoronary stent implantation after failed angioplasty. None underwent emergency coronary bypass surgery. One patient (4%) had a myocardial infarction and 2 patients (7%) died during hospitalization, the first because of abrupt vessel closure during angioplasty, the second due to acute retroperitoneal bleeding on the 8th day post-angioplasty while fully anticoagulated for an intracoronary stent. Follow-up (median 17, range 8 to 39 months) was obtained for all patients. Out of the 21 patients with primary angioplastic success, 3 (14%) had died (1 cardiac and 2 non-cardiac). At 1 year actuarial survival was 86%, and survival free from myocardial infarction or coronary bypass surgery was 81%. Further angioplasty for either restenosis or another lesion was performed in 5 patients (24%). These results confirm that coronary angioplasty is an effective means of controlling anginal symptoms in a selected group of severely symptomatic octogenarians. However, when complications do occur they are linked to a significant mortality rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

[Closure of patent ductus arteriosus using interventional catheterization].

Percutaneous closure of patent ductus arteriosus can be performed with the Rashkind technique. This procedure has been performed in 16 patients in Geneva since 1989. The age of the patients varied from 2 to 44 years (4 boys, 7 girls, and 5 women). Pulmonary hypertension was present in only 1 child. A 12 mm Rashkind umbrella was used in 11 patients with ductus of < or = 4 mm inner diameter, while a 17 mm umbrella was used in 5 cases for larger ducts. Ductus closure was carried out through a transvenous femoral approach in 15 cases, while in 1 patient a transarterial approach was employed because of impossibility of passing the ductus from the pulmonary artery. There was neither mortality nor morbidity in this series. The aortography performed just after device placement showed total ductus occlusion in 8 patients and partial closure in 8 others. The follow-up by color Doppler showed disappearance of the residual shunt in 4 of these 8 patients. Prophylaxis of bacterial endocarditis is therefore no longer necessary in 13 patients with complete ductus closure. Our experience with this technique confirms its efficacy and the possibility it offers of avoiding thoracotomy in the vast majority of patients with a patent ductus arteriosus. Further miniaturization of the device and delivery system should make it applicable in the neonatal period.

Adolescent↗
PubMed1993

[Indications for coronary dilatation and bypass surgery].

Coronary artery disease is the dominant disorder in industrialized countries. It can be treated by drugs, coronary angioplasty, or bypass surgery. Angioplasty has become the most frequent mode of active therapy. Local variations in the use of treatment modalities can be explained mainly by early detection of coronary artery disease yielding more candidates for angioplasty. All indications should be based on a combination of symptoms, objective signs of ischemia (e.g., stress test) and angiographic correlates. Coronary angioplasty is limited to the less complex cases such as single vessel disease (except for diffuse disease, old total occlusions), double vessel disease with up to 3 discrete lesions or lesions in secondary vessels, and, exceptionally, triple vessel disease of the appropriate kind (usually in 2 sessions). These limitations arise from the drawbacks of the method, i.e., acute occlusion (about 7%), recurrence (about 30%), and technical failures (about 5%). For acute myocardial infarction, direct coronary angioplasty is probably the method of choice, provided it can be performed within 30 minutes after diagnosis. For unstable angina, the results are inferior to those obtained with stable symptomatology; compared with the spontaneous prognosis, they remain nonetheless beneficial. The same holds true for angioplasty in elderly patients, where the reduced chances of success must be viewed in light of a typically very severe clinical picture. Angioplasty is often a blessing for young patients. It allows immediate resumption of a normal life and is easily repeatable over the years. Indications for coronary bypass surgery should not be deduced from the randomized studies of the seventies. They concentrated on survival, and surgical methods have been refined since.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

The cytochrome b-558 molecules involved in the fibroblast and polymorphonuclear leucocyte superoxide-generating NADPH oxidase systems are structurally and genetically distinct.

We have demonstrated that human fibroblasts can release O2-. radicals by an NADPH oxidase system that appears to be functionally similar to the phagocytic system. Further analysis of these systems, however, with respect to the low-potential b-type cytochromes involved suggests that these two O2-.-generating systems are not structurally identical. Immunoblot analysis of fibroblast membranes with six different antibodies directed against both subunits of human neutrophil cytochrome b-558 indicated that the b-type cytochrome molecules involved in these systems were not identical. None of these anti-(neutrophil cytochrome b) antibodies recognized a similar cytochrome in fibroblast membranes, suggesting that the two cytochrome species are immunologically distinct. In addition, fibroblasts obtained from a patient suffering from X-linked chronic granulomatous disease (CGD) had a normal cytochrome b-558 content compared with control fibroblast membranes, whereas the cytochrome b-558 concentration in polymorphonuclear leucocytes (PMNs) from this patient was decreased to 10% of that found in PMNs from healthy controls. Likewise, the stimulated O2-. release in PMNs from this patient was less than 10% of that in control PMNs, whereas the fibroblasts showed stimulated O2-.-release rates that were indistinguishable from those of fibroblasts obtained from healthy persons. Since the genetic mutation responsible for this type of CGD results in the absence of cytochrome b-558 in PMNs, fibroblasts should be affected in the same way if both cytochrome species were identical. These results suggest therefore that the low-potential b-type cytochromes in PMNs and fibroblasts are structurally and genetically distinct.

Antibodies↗
PubMed1993

Coronary stenting through 6 French guiding catheters.

Most stent implantation procedures currently require the use of large-diameter guiding catheters. We describe our preliminary successful experience with 6 French guiding catheters to deliver balloon-expandable Palmaz-Schatz stents to the coronary arteries.

Aged↗
PubMed1993

Coronary angioplasty through 4 French diagnostic catheters.

In 50 consecutive patients subjected to coronary angioplasty immediately following a 4 French (F) diagnostic study, the technical feasibility and economical aspects of angioplasty through 4F catheters of 54 lesions were assessed. The patients were selected, but multiple, eccentric, and long lesions were not a priori excluded. 4F diagnostic catheters (Cordis), and fixed-wire dilatation catheters (Ace, Scimed) were used in all cases. The procedure was successful in 43 lesions (80%) using 4F catheters. For 11 stenoses (20%), a change over to a larger French size was required. Two of these lesions could not be crossed with the balloon despite the larger sized guiding catheter. The final overall success rate was 96%, and there were no major complications. The use of diagnostic 4F catheters for angioplasty in these 50 patients resulted in the saving of 39 guiding catheters and 19 introducer sheaths. For 12 lesions (22%), an additional 4F catheter became necessary since the shape used for the diagnostic study was inadequate for angioplasty. In 7 cases, more than 1 balloon was used, but 5 of these balloon exchanges were independent of the use of 4F catheters. Three exchanges were performed through the 4F catheter (1 for need of a larger balloon to improve on an unsatisfactory angiographic result and 2 for a crimped guide wire tip of the Ace balloon). In the remaining 4, a larger catheter was used; in 2 of them, angioplasty eventually failed (failure to cross lesion) and in the remaining 2, a Monorail system solved the problem, which is incompatible with 4F catheters.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1993

Comparison of planar imaging and single-photon emission computed tomography for the detection and localization of coronary artery disease.

Although single photon emission computed tomography (SPECT) has become widely utilized, the superiority of this technique compared to planar conventional imaging remains controversial. In order to compare these two techniques, we retrospectively analysed the results obtained in 70 patients who performed a thallium-201 exercise scintigraphy with a double acquisition during the same test, and who also underwent coronary and ventricular angiography. Overall, SPECT imaging yielded a higher sensitivity (93% vs 82% for SPECT and planar imaging respectively, p < 0.05), especially in the inferior and anterior regions. SPECT was also more sensitive for the detection of a single-vessel disease (90% vs 74% for SPECT and planar imaging respectively, p < 0.01). The specificity was assessed for both techniques with the help of circumferential computerized analysis, avoiding known causes of false positive scintigrams. We found a high specificity for both SPECT and planar imaging, without any significant difference between the two methods (87% vs 91% for the overall specificity of SPECT and planar imaging respectively, p = NS). Therefore, SPECT imaging analysed with discrimination shows an enhanced reliability over planar imaging for the detection and the localization of coronary artery disease, without increasing the risk of false positive tests.

Coronary Disease↗