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Biomedical subjects

U Sigwart

Publications and source records attributed to U Sigwart.

At least 19 recordsLinked to original sources
PubMed1992

Quantitative angiographic follow-up of the coronary Wallstent in native vessels and bypass grafts (European experience--March 1986 to March 1990).

The coronary stent has been investigated as an adjunct to percutaneous transluminal coronary angioplasty to obviate the problems of early occlusion and late restenosis. From March 1986 to March 1990, 265 patients (308 lesions) were implanted with the coronary Wallstent in 6 European centers. For this study, the patients were analyzed according to date of implantation (group 1, March 1986 to January 1988; group 2, February 1988 to March 1990) and vessel type (native arteries versus bypass grafts). Quantitative angiographic follow-up was performed in 82% of the study patients. The early in-hospital occlusion rate in the overall group was 15%. Group 1 patients had a 20% rate in contrast to 12% rate in group 2 (p = not significant [NS]). The early occlusion rate in native vessels and bypass grafts was 19 and 8%, respectively (p = 0.019). Restenosis was determined by 2 criteria (criterion 1, greater than or equal to 0.72 mm loss in minimal luminal diameter from poststent to follow-up; criterion 2, greater than or equal to 50% diameter stenosis at follow-up) within the stent and in the segments immediately proximal and distal to the stent. The restenosis rate with criterion 1 was 43% in the overall group of patients, 35% in group 1 versus 49% in group 2 (p = NS), and 34% in native vessels versus 54% in bypass grafts (p = 0.016). The second criterion was met by 27% of patients in the overall group, 21% in group 1 versus 32% in group 2 (p = NS), and 18% in native vessel versus 39% in bypass grafts (p = 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1992

Angiographic restenosis after successful Wallstent stent implantation: an analysis of risk predictors.

Follow-up angiographic study was performed in 86 patients after initially successful Wallstent stent (Medinvent, Lausanne, Switzerland) implantation between April 1986 and October 1990. The stent angiographic restenosis rate was 16% at a mean of 8 months after stenting despite the inclusion of a substantial number of patients at high risk of restenosis after percutaneous transluminal coronary angioplasty (PTCA). Of a total 15 variables analyzed, only suboptimal stent placement was found to be a significant predictor of stent restenosis. Age; gender; baseline New York Heart Association functional class; previous PTCA; indication for stenting; left ventricular ejection fraction; preangioplasty and immediate postangioplasty diameter stenosis severity; stented vessel site, lesional morphology; number, diameter, and length of stents implanted; and the interval between stenting and follow-up angiographic restudy were not significant risk factors of stent restenosis. Our study suggests that intracoronary stent implantation with the Wallstent may be a useful and promising adjunctive option after PTCA, particularly in patients at high risk of restenosis after PTCA. However, because of the significantly enhanced risk of restenosis after suboptimal stent implantation, we strongly recommend the selection and placement of Wallstent stents that adequately cover the entire length of the dilated coronary segment.

Adult↗
PubMed1992

Novel coronary interventional devices: an update.

Interventional cardiologists today are overwhelmed by a hugh array of new high technology investigatory devices at their disposal for the treatment of coronary arterial obstructive disease. These include the various atherectomy and laser devices, developed and introduced into clinical practice with the promise and intent of solving the limitations of conventional balloon angioplasty, namely those of acute closure and restenosis. But as more experience and data are obtained from the application of these devices, it is becoming clear that the latter have generally not been able to accomplish what they were intended to do. Although the immediate success rates have been uniformly high, acute closure has persisted and restenosis remains unabated. Nevertheless, some of these new devices have shown some fairly encouraging results in specific clinical circumstances. The targeted use of these instruments may prove to be a step in the right direction. This article reviews the current state of the art and the potential utility of certain of these devices.

Angioplasty, Balloon, Coronary↗
PubMed1992

Long-term clinical and angiographic follow-up of patients treated with the self-expanding coronary stent for acute occlusion during balloon angioplasty of the right coronary artery.

A self-expanding coronary stent was implanted in 17 patients to treat acute occlusion of the right coronary artery after percutaneous transluminal angioplasty. There were 2 women and 15 men, with a mean age of 59 +/- 8 years. All patients underwent at least one follow-up angiographic examination 4 to 6 months after implantation and six patients had additional follow-up angiography. During a mean follow-up interval of 32 +/- 10 months no patient died or had a myocardial infarction. Restenosis within the stent did not occur. Two patients had a new stenosis adjacent to the stent. Stent occlusion was found on follow-up angiography in one patient who had not been treated with an antiplatelet agent. The mean intraluminal diameter was 2.77 +/- 0.5 mm after implantation and 2.67 +/- 0.5 mm on follow-up angiography. It is concluded that coronary stenting is effective in treating right coronary artery occlusion after balloon angioplasty. Immediate and long-term outcome suggest that the right coronary artery may be a particularly favorable site for stent implantation.

Angioplasty, Balloon, Coronary↗
PubMed1992

Left atrial and left ventricular diastolic function during acute myocardial ischaemia.

OBJECTIVE: To study indices of diastolic left ventricular function during the first few seconds of myocardial ischaemia. DESIGN: Isovolumic and total relaxation times and left atrial and left ventricular dP/dt were identified from high fidelity (micromanometer) pressure recordings in the left ventricle and left atrium during percutaneous transluminal angioplasty of the left anterior descending coronary artery. PATIENTS: 20 patients with isolated disease of the left anterior descending artery and normal left ventricular function. RESULTS: The isovolumic relaxation time lengthened during the first seven to nine seconds of ischaemia; then it shortened by an average of 15% up to the twentieth second, initially as a result of increased left atrial contractility and subsequently because of impaired ventricular relaxation. Ventricular ischaemia resulted in impaired left ventricular diastolic compliance, as shown by an increase in the total relaxation time, before there was evidence of systolic impairment. Minimum dP/dt decreased progressively (by -37% at the twentieth second of ischaemia), whereas maximum dP/dt fell only after 20 seconds of ischaemia (by -11%). CONCLUSIONS: Relaxation and filling of the left ventricle (indices of diastolic function) are more sensitive to myocardial ischaemia than myocardial contractility and systolic function. Left atrial contractility increases during left ventricular ischaemia.

Adult↗
PubMed1992

The current status of intracoronary stent: an overview.

Intracoronary stenting is a relatively new therapeutic interventional modality conceived to address the 2 major pitfalls of conventional balloon angioplasty, namely that of acute closure and restenosis. Much progress has been made since its clinical application in 1986. Its place amongst the multitude of novel devices currently available in the treatment of coronary obstructive disease seems secure. The challenge for investigators now is to develop a stent without the inherent problem of acute thrombosis.

Angioplasty, Balloon, Coronary↗
PubMed1991

Long-term follow-up of the first 56 patients treated with intracoronary self-expanding stents (the Lausanne experience).

Fifty-six patients treated with the self-expanding intracoronary stent for acute occlusion during percutaneous transluminal coronary angioplasty (PTCA) or restenosis were followed for 24 to 43 months (mean 34). Successful deployment and positioning were achieved in 55 of 56 patients. Occlusion of the stent was documented in 8 patients, the earliest occurring 30 minutes and the latest 8 months after implantation. Three of the occluded stents were recanalized by PTCA. Coronary artery bypass grafts (CABG) were required in 4 patients: 1 for symptomatic restenosis, 1 for left main stenosis adjacent to the stent and 2 for acute ischemia during the in-hospital stay (less than 7 days). Myocardial infarction occurred in the territory of the stented vessel in 8 patients. Seven patients died between 1 day and 19 months after implantation. Local bleeding complications occurred in 10 patients, with 5 requiring blood transfusion. Restenosis within the stent was angiographically documented in 5 patients (9%). A new lesion in the treated vessel was found in 10 patients, followed by implantation of a second stent in 5 and a third stent in 1 patient. Medical treatment was instituted in the remaining 4 patients. Forty-nine patients (88%) are alive. Twenty-nine patients (51%) remained asymptomatic, and 44 (78%) are in a better functional class than before the implantation. Eleven of 15 (79%) major complications (acute occlusions or deaths) occurred in patients who received a stent in the left anterior descending coronary artery. In conclusion, implantation of the self-expanding intracoronary stent appears to be a new therapeutic option for treating acute occlusion or restenosis after PTCA.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1991

Successful stenting of a life threatening pulmonary arterial stenosis.

A 35 year old woman with multiple pulmonary arterial stenoses and occlusions was admitted with increasingly severe breathlessness. Balloon angioplasty of a life threatening stenosis in a remaining pulmonary artery branch was attempted on two occasions but without success. When a self-expanding stainless steel stent was inserted at the site of stenosis after a further angioplasty acute localised pulmonary oedema developed as blood flow distal to the lesion increased considerably. This was followed by a slow and dramatic improvement in the patient's condition. She no longer required an urgent transplant and resumed an active life.

Adult↗
PubMed1990

Left atrial function in acute transient left ventricular ischemia produced during percutaneous transluminal coronary angioplasty of the left anterior descending coronary artery.

Left atrial (LA) function was studied in 32 patients during percutaneous transluminal coronary angioplasty of the proximal left anterior descending artery with a dual micromanometer positioned transseptally in the left atrium and in the left ventricle. In 10 patients LA and left ventricular (LV) cineangiography was performed 30 minutes before percutaneous transluminal coronary angioplasty and 30 seconds after the occlusion of the left anterior descending coronary artery. Thirty seconds after left anterior descending occlusion, LV peak systolic pressure decreased from 135 +/- 12 to 106 +/- 9 mm Hg (p less than 0.05) and LV maximum dP/dt decreased from 1,634 +/- 136 to 1,137 +/- 127 mm Hg/s (p less than 0.01). Simultaneously, LA mean pressure increased from 11 +/- 2 to 29 +/- 1 mm Hg (p 177 +/- 13 to 381 +/- 21 mm Hg (p less than 0.001). There was a difference between LV end-diastolic pressure and LA mean pressure of 1.5 mm Hg at rest and 7.8 mm Hg during ischemia and LA pulse pressure increased from 16 +/- 3 to 26 +/- 3 mm Hg (p less than 0.05) together with increase of LA A and V waves peak pressure. LV stroke volume index decreased from 46 +/- 5 to 43 +/- 3 ml/m2 (difference not significant). The LA maximal volume increased from 18 +/- 2 to 29 +/- 3 ml/m2 (p less than 0.001). LA volume before LA contraction increased from 29 +/- 2 to 54 +/- 3 ml/m2 (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1990

[Coronary endoprostheses (stents)].

Even before the introduction of transluminal balloon dilatation of coronary arteries, Dotter had conceived intravascular endoprostheses and, in 1969, published a report of his observations after implantation of a spiral-shaped support of surgical steel and nickel-titanium ligation in peripheral arteries of the dog. Interest in intravascular supports developed especially in consideration of frequent unsatisfactory long-term results after coronary angioplasty. Coronary artery occlusion is observed in about 5% of balloon dilatations due to dissection, thrombosis, spasm or a combination of these phenomena. The rate of recurrent stenosis after uncomplicated balloon dilatation is about 30%, that of recanalization of chronic occlusion or dilatation of stenosed bypass grafts about 50%. Stent technology: In order to provide a meaningful solution to unresolved problems of balloon dilatation, the ideal endoprosthesis must be rapidly and reliably implantable as well as sufficiently flexible to conform to vascular curvatures. It should have a low profile, must be biocompatible and not thrombogenic; it should be rapidly endothelialized with no excessive proliferatory stimulus. Rigid stents are limited in length; elastic stents display a better transition to normal coronary arteries. Negatively-charged metallic surfaces appear less thrombogenic than those positively charged, the former, however, are usually not free of corrosion. The generally positive charge of stainless steel, the most commonly used material, is tempered with a special surface treatment. Currently, materials under investigation are nickel-titanium, tantalum and biodegradable plastic. Of importance for endothelialization are the wall thickness of the stent and the relationship of material to pore size. Filaments of stainless steel measuring 0.09 mm in diameter are completely covered by neoendothelium within three weeks. In laboratory animals, within minutes after implantation, all three stents currently in clinical use are covered with a thin layer of thrombocytes and fibrin; after one day, endothelial-like and pseudoendothelial cells develop along the metal structures. After one week, there is a flow-oriented behaviour of the surface cell formation embedding the stent between neoendothelial and lamina elastica interna, a process which is complete in three months. The thickness of the neointimal proliferation may be dependent on the stent geometry and may vary between 0.09 and 0.4 mm.(ABSTRACT TRUNCATED AT 400 WORDS)

Angioplasty, Balloon, Coronary↗
PubMed1989

[Immediate and late complications secondary to the implantation of a coronary endoprosthesis].

The incidence of acute and late complications after coronary stenting has been studied in 95 consecutive patients. A total of 113 stents were implanted: 23 cases for acute occlusion of the dilated vessel and 72 for restenosis. After 16 months of follow-up, minor complications had occurred in 22 patients (23%). They consisted of transient occlusion of the prosthesis in 7 patients (7.3%), non-Q wave infarction in 4 patients (4.2%) and 10 hemorrhages (11%). During the following period major complications were observed in 11 patients (12%) with myocardial infarction in 7 instances and acute occlusion in 7 patients. 5 patients (5.3%) underwent coronary artery bypass graft and 6 (6.3%) died (one in-hospital death). Two deaths were related to the stent, but in the other four no definite correlation between the prosthesis and the death could be demonstrated. Restenosis at 12 months was present in 4 cases: in 3 patients (4.7%) where the stent had been implanted for restenosis and 1 (4.7%) where it had been implanted for acute occlusion. We conclude that for selected patients, coronary stenting is a promising new technique, especially for acute occlusion after PTCA; moreover, at 12 months restenosis is less frequent than after PTCA. However, technical improvement is necessary to diminish the rate of complications, particularly thrombosis and hemorrhage.

Aged↗
PubMed1989

Phospholipids and other lipids in angiographically assessed coronary artery disease.

Lipoprotein subclasses and their composition in cholesterol, triglycerides and in 5 types of phospholipid as well as apolipoproteins A-I and B were determined in blood of 114 patients undergoing coronary angiography for suspected or confirmed myocardial ischaemia. Lipid concentrations of lipoproteins were measured after preparative ultracentrifugation; high performance thin-layer chromatography was used to separate phospholipid subfractions. Patients with angiographically defined coronary artery disease (CAD) significantly differed from those without CAD in 25 different lipid or phospholipid parameters. Using discriminative analysis, apo A-I/apo B ratio was the only parameter with more than 70% success in reclassifying the patients in the CAD group. When correlated with a coronary atheromatous score reflecting either the number and degree of stenoses (Jenkins score) or the number of diseased vessels alone, only LDL-cholesterol was found to correlate with the Jenkins score. We conclude that serum phospholipid fractions may differ significantly in CAD group as compared with controls, but they are, however, no better predictors of CAD than other lipids.

Adult↗
PubMed1989

Intravascular stenting for stenosis of aortocoronary venous bypass grafts.

To test the ability of endoluminal stents to prevent saphenous vein graft restenosis after balloon angioplasty, 13 patients with angina and previous coronary bypass surgery underwent implantation of one or more stents into 14 stenosed grafts. Implantation was technically successful in all cases and there were no major in-hospital complications. During a median follow-up interval of 7 months (range 2 to 26), 10 patients (77%) underwent follow-up angiography. Seven patients remained asymptomatic or in improved condition without further intervention; three patients had further angioplasty with stent implantation for a new stenosis in the same graft. Two patients (20%) developed within-stent restenosis. There was one death from progressive congestive heart failure 7 months after implantation. No patient had a myocardial infarction or needed surgical revascularization during the follow-up period. In selected cases, stent implantation appears to be a promising new technique that may decrease the incidence of restenosis after balloon angioplasty in venous bypass grafts. The rate of complications is low. Further experience and longer follow-up will be needed before definite recommendations can be made about its use.

Aged↗