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Biomedical subjects

I Moussa

Publications and source records attributed to I Moussa.

At least 37 records · Page 2Linked to original sources
PubMed1999

Does the specific intravascular ultrasound criterion used to optimize stent expansion have an impact on the probability of stent restenosis?

Intravascular ultrasound (IVUS) imaging has been used to optimize stent implantation in coronary arteries, but the criteria used were chosen on an empiric basis. The aim of this study was to determine whether any of these criteria have an independent role in predicting the probability of freedom from restenosis. The study population consisted of 425 patients (496 lesions) who underwent angiographically successful IVUS-guided stenting. Five IVUS criteria were studied: (1) intrastent minimal lumen cross-sectional area (ISMLCSA) > or =9 mm2; (2) ISMLCSA (> or =9 mm2 and > or =80% of average reference lumen cross-sectional area [CSA]); (3) ISMLCSA > or =90% of average reference lumen CSA; (4) ISMLCSA > or =90% of distal reference lumen CSA; and (5) ISMLCSA > or =55% of average reference vessel CSA. These criteria were met in 33%, 29%, 68%, 82%, and 69% of lesions, respectively. Angiographic follow-up was performed in 335 of 421 eligible patients (80%) at 5.3 +/- 2.7 months. An absolute ISMLCSA > or =9 mm2 was associated with the lowest restenosis, but this criterion was primarily achieved in large vessels. The only criterion that was associated with higher probability of freedom from restenosis independently from vessel size was an ISMLCSA > or =55% of average reference vessel CSA. Therefore, when IVUS is used to guide stent implantation an effort should be made to achieve the largest lumen safely possible. An ISMLCSA > or =55% of the average reference vessel CSA seems to be the most appropriate criterion in terms of frequency of achievement and in terms of increasing the probability of freedom from restenosis.

Coronary Angiography↗
PubMed1999

In-stent neointimal proliferation correlates with the amount of residual plaque burden outside the stent: an intravascular ultrasound study.

BACKGROUND: The aim of this study was to evaluate the relationship between residual plaque burden after coronary stent implantation and the development of late in-stent neointimal proliferation. METHODS AND RESULTS: Between January 1996 and May 1997, 50 patients underwent intravascular ultrasound (IVUS) interrogation at 6+/-1.2 months after coronary stent implantation in native coronary arteries. IVUS images were acquired with a motorized pullback, and cross-sectional measurements were performed within the stents at 1-mm intervals. The following measurements were obtained: (1) lumen area (LA), (2) stent area (SA), (3) area delimited by the external elastic membrane (EEMA), (4) percent neointimal area calculated as (SA-LA/SA)x100, and (5) percent residual plaque area calculated as (EEMA-SA)/EEMAx100. Volume measurements within the stented segments were calculated by applying Simpson's rule. In the pooled data analysis of 876 cross sections, linear regression showed a significant positive correlation between percent residual plaque area and percent neointimal area (r=0.50, y= 45.03+0.29x, P<0.01). There was significant incremental increase in mean percent neointimal area for stepwise increase in percent residual plaque area. Mean percent neointimal area was 16.3+/-10.3% for lesions with a percent residual plaque area of <50% and 27.7+/-11% for lesions with a percent residual plaque area of >/=50% (P<0.001). The volumetric analysis showed that the percent residual plaque volume was significantly greater in restenotic lesions compared with nonrestenotic lesions (58.7+/-4.3% versus 51.4+/-5.7%, respectively; P<0.01). CONCLUSIONS: Late in-stent neointimal proliferation has a direct correlation with the amount of residual plaque burden after coronary stent implantation, supporting the hypothesis that plaque removal before stent implantation may reduce restenosis.

Aged↗
PubMed1999

Lower restenosis rate with stenting following aggressive versus less aggressive rotational atherectomy.

The present study evaluated the acute and follow-up results of stenting following aggressive rotational atherectomy compared with stenting following less aggressive rotational atherectomy. Recent work has demonstrated that stenting following rotational atherectomy is a promising strategy for complex and calcified lesions. However, there is little information available regarding the optimal procedural technique of rotational atherectomy to be employed before stent implantation. Between May 1995 and February 1997, 162 lesions in 126 patients were stented following rotational atherectomy because of the presence of severe calcification on fluoroscopy or intravascular ultrasound (95%). The lesions were divided as to whether aggressive rotational atherectomy was performed or not. Aggressive rotational atherectomy, defined as the use of a final burr size > or =2.25 mm and/or final burr/vessel ratio > or =0.8, was performed in 56 lesions. A less aggressive rotational atherectomy strategy was performed in 106 lesions. Procedural Q-wave (8.9% vs. 1.9%, P<0.05) and non-Q-wave (11% vs. 1.9%, P<0.05) myocardial infarctions were observed more frequently after aggressive rotational atherectomy; there was no significant difference in the incidence of other procedural complications. Although there was no significant difference in minimal lumen diameter after the procedure (3.11+/-0.68 vs. 2.99+/-0.48 mm, NS), at follow-up a greater minimal lumen diameter was observed in the lesions treated with aggressive rotational atherectomy compared to those treated with less aggressive rotational atherectomy (2.12+/-1.31 vs. 1.56+/-0.89 mm, P<0.01). Restenosis rates were 50.0% in the lesions treated without aggressive rotational atherectomy and 30.9% in those treated with aggressive rotational atherectomy (P<0.05). There was no significant difference in the incidence of restenosis with a focal pattern between the two groups (25.0% vs. 21.4%, NS). In contrast, restenosis with a diffuse pattern was lower in lesions treated with aggressive rotational atherectomy than in those without aggressive rotational atherectomy (9.5% vs. 25.0%, P<0.05). Aggressive rotational atherectomy followed by stenting is a promising strategy to reduce the restenosis rate in calcified lesions. However, the aggressive strategy is associated with an increased risk of procedural myocardial infarction.

Calcinosis↗
PubMed1999

Risk of distal embolization and infarction with transluminal extraction atherectomy in saphenous vein grafts and native coronary arteries. NACI Investigators. New Approaches to Coronary Interventions.

Lower success rates have been reported when treating high-risk lesions in saphenous vein grafts (SVGs) and native coronary arteries with balloon angioplasty. The transluminal extraction atherectomy catheter (TEC) has been proposed to reduce the incidence of distal embolization (DE) in subsets of high-risk lesions. To define the utility of TEC in reducing the incidence of DE, all patients who were enrolled in the New Approaches to Coronary Interventions (NACI) Registry and had TEC planned as the sole treatment were studied (329 patients with 381 lesions). Of the lesions treated, 75.9% were in SVGs; 37.5% were thrombotic; and 15% were total occlusions. Adjunctive percutaneous transluminal coronary angioplasty (PTCA) was performed in 87.4% of lesions. Multivariate predictors of DE were: noncardiac disease, stand alone TEC, thrombus, and larger vessel size. DE was associated with an 18.5% in-hospital mortality vs. 3.0% without DE (P < 0.01) and a 25.9% MI rate vs. 5.0% without DE (P < 0.01). In conclusion, in this high-risk subset of patients, TEC is associated with an 8.3% incidence of DE with thrombotic and SVGs lesions. DE associated with TEC appears to carry high morbidity and mortality. Additional techniques to control DE are needed to reduce the frequency of complications in these patients.

Aged↗
PubMed1999

Do new devices add to the results of PTCA in acute myocardial infarction?

Several randomized trials have established that timely mechanical reperfusion with the use of balloon angioplasty is superior to thrombolytic therapy in patients with acute myocardial infarction. Furthermore, recent data from prospective randomized trials suggest that primary stent implantation may further improve the results of balloon angioplasty by reducing the need for repeat interventions at follow-up. The role of IIb-IIIa platelet receptor antagonists as adjunctive therapy to catheter-based coronary interventions in acute myocardial infarction is promising, but the incremental benefit that these agents add to stent implantation awaits the results of dedicated randomized trials. Mechanical thrombolysis or thrombectomy devices may have a role in a minority of patients with large thrombus burden.

Angioplasty, Balloon, Coronary↗
PubMed1999

Substituted amylose as a matrix for sustained drug release.

PURPOSE: Amylose derivatives form an important group of polymers, and many of them can be used as drug sustained-release systems. METHODS: Substituted amylose can be prepared in a 1-step reaction with substituent(s) in a basic medium. The substituents can be represented as (A-R), where (A) serves an epoxy, halide or suitable organic or inorganic function reacting with hydroxyl groups located on the amylose chain, and (R) is an organic radical. RESULTS: The present work shows the synthesis of different polymers and the effect of different (A) and/or (R) and their different degrees of substitution (n) on the sustained drug release from matrix tablets prepared by direct compression. CONCLUSIONS: SA polymers are interesting excipients for the preparation of controlled drug release tablets.

Acetaminophen↗
PubMed1999

Outpatient carotid artery stenting: a case report.

PURPOSE: To report a case of carotid artery stenting for asymptomatic carotid restenosis performed in an outpatient setting. METHODS AND RESULTS: A 68-year-old man with right carotid restenosis after repeat carotid endarterectomy underwent carotid angioplasty and stenting on an ambulatory basis. The procedure to implant a Smart stent required 45 minutes; the femoral access site was closed with a puncture closure device. The patient experienced no sequelae to this procedure and is well 6 months after treatment. CONCLUSIONS: Outpatient delivery of percutaneous carotid stenting may be feasible in appropriately selected patients.

Aged↗
PubMed1998

Angiographic and clinical outcome following coronary stenting of small vessels: a comparison with coronary stenting of large vessels.

OBJECTIVES: Stent implantation reduces restenosis in vessels > or =3 mm compared with balloon angioplasty, but few data are available for stents implanted in vessels <3 mm. The aim of this study was to evaluate immediate and follow-up patient outcomes after stent implantation in vessels <3 mm compared to stent implantation in vessels > or =3 mm. METHODS: Between March 1993 and May 1996, a total of 1,298 consecutive patients (1,673 lesions) underwent coronary stenting. The study population was divided into two groups based on angiographic vessel diameter. In case of multivessel stenting, patients were randomly assigned only one lesion. Group I included 696 patients (696 lesions) in whom stents were implanted in vessels > or =3 mm, and group II included 602 patients (602 lesions) in whom stents were implanted in vessels <3 mm. RESULTS: There was no difference in procedural success (95.4% in group I and 95.9% in group II), or subsequent subacute stent thrombosis (1.5% in group I and 1.4% in group II, p=NS). The postprocedure residual diameter stenosis was 3.31+/-12.4% in group I and -2.45+/-16.2% in group II. Angiographic follow-up was performed in 75% of patients, restenosis occurred in 19.9% of patients in group I and 32.6% in group II (p <0.0001). Absolute lumen gain was significantly higher in group I compared to group II, but absolute late lumen loss was similar in the two groups (1.05+/-0.91 mm in group I vs. 1.11+/-0.85 mm in group II, p=NS). Subsequently, the loss index was more favorable in group I (0.45 vs. 0.56; p=0.0006). Independent predictors of freedom from restenosis by multivariate logistic regression in the total population were: larger baseline reference diameter (odds ratio 2.032 p=0.006), larger postprocedure minimal stent cross-sectional area (odds ratio 1.190, p=0.0001) and shorter lesions (odds ratio 1.037, p=0.01). At long-term clinical follow-up, patients with small vessels had a lower rate of event-free survival (63% vs. 71.3%, p=0.007). CONCLUSIONS: Coronary stenting can be performed in small vessels with a high success rate and low incidence of stent thrombosis. However, the long-term angiographic and clinical outcome of patients undergoing stent implantation in small vessels is less favorable than that of patients with large vessels.

Aged↗
PubMed1998

Stenting after optimal lesion debulking (sold) registry. Angiographic and clinical outcome.

BACKGROUND: Coronary stenting has reduced restenosis in focal de novo lesions, but its impact has been less pronounced in complex lesion subsets. Preliminary data suggest a role for plaque burden in promoting intimal hyperplasia after stent implantation. The aim of this study was to test the hypothesis that plaque removal with directional atherectomy before stent implantation may lower the intensity of late neointimal hyperplasia, reducing the incidence of in-stent restenosis. METHODS AND RESULTS: Seventy-one patients with 90 lesions underwent directional atherectomy before coronary stenting. Intravascular ultrasound-guided stenting was performed in 73 lesions (81%). Clinical success was achieved in 96% of patients. Procedural complications were as follows: emergency bypass surgery in 1 patient (1.4%), who died 2 weeks later; Q-wave myocardial infarction in 2 patients (2.8%); and non-Q-wave myocardial infarction in 8 patients (11.3%). None of the patients had stent thrombosis at follow-up. Angiographic follow-up was performed in 89% of eligible patients at 5.7+/-1.7 months. Loss index was 0.33 (95% CI, 0.26 to 0.40), and angiographic restenosis was 11% (95% CI, 5% to 20%). Clinical follow-up was performed in all patients at 18+/-3 months. Target lesion revascularization was 7% (95% CI, 3% to 14%). CONCLUSIONS: Directional atherectomy followed by coronary stenting could be performed with good clinical success rate. Also, these data point to a possible reduction in angiographic restenosis and a significant reduction in the need for repeated coronary interventions. Therefore, a randomized clinical trial seems appropriate to test the validity of this approach.

Aged↗
PubMed1998

Cross-linked high amylose starch for controlled release of drugs: recent advances.

Cross-linked high amylose starches have been developed as excipients for the formulation of controlled-release solid dosage forms for the oral delivery of drugs. Advantages of this new class of excipients include cost-effectiveness, readily accessible industrial manufacturing technology, high active ingredient core loading and the possibility of achieving a quasi zero-order release for most drugs. In addition to the latter, other features distinguish cross-linked high amylose starches from other excipients used to prepare hydrophilic matrices. Among these are the absence of erosion, the limited swelling and the fact that increasing cross-linking degrees results in increased water uptake rate, drug release rate and equilibrium swelling. Thus the goal of the present study was to gain some insights into the mechanism of drug release control by matrices of cross-linked high amylose starch. Water transport kinetics and dimensional changes were studied in matrices placed in water at 37 degrees C by an image analysis technique. The results show that in the first 5 min, a gel layer is formed at the surface of the tablet, after which the gel front seems to halt its progression toward the center of the tablet. Water continues to diffuse through the front and to invade the core. As a consequence, this latter swells, with a predominance for radial swelling. Equilibrium swelling is reached over 3 days, when the water concentration in the tablet becomes homogeneous and the whole tablet gelifies. Solid-state 13C-NMR were acquired on cross-linked high amylose starch powders, tablets and hydrated tablets with varying cross-linking degrees. They show a predominance of the V-type single helix arrangement of amylose in the dry state irrespective of the cross-linking degree. Upon hydration, the homologues with a low cross-linking degrees show a transition from the V to the B-type double helix arrangement. It is therefore hypothesized that the capacity of amylose to undergo the V to B transition is an important factor in controlling water transport and drug release rate. Finally applications to different drugs are reviewed briefly. They illustrate the versatility of this technology as generic versions of zero order OROS drug (Efidac) and Fickian release conventional matrices (Voltaren SR) were developed and successfully tested in pilot clinical studies to be bioequivalent to the references. These studies further showed that cross-linked high amylose starch matrices have the lowest inter-subject variability among the systems tested and show a total absence of food effect.

Administration, Oral↗
PubMed1998

Comparison of angiographic and clinical outcomes of coronary stenting of chronic total occlusions versus subtotal occlusions.

The objective of this study was to assess the short- and long-term outcome of patients undergoing coronary stenting for chronic total occlusions compared with a control patient population with nonocclusive stenoses. A total of 789 consecutive patients (1,043 lesions) underwent coronary stenting using a high-pressure stent optimization technique. The study population was divided into total occlusion group (94 consecutive patients [95 lesions] with chronic total occlusions) and subtotal occlusion group (695 consecutive patients [948 lesions] with nonocclusive stenoses). There was no difference in post-procedure angiographic minimum lumen diameter (3.13 +/- 0.48 vs 3.15 +/- 0.57 mm, p = 0.72) and minimum intrastent cross-sectional area by intravascular ultrasound (7.31 +/- 2.06 vs 7.64 +/- 2.53 mm2, p = 0.26) between the total and subtotal groups, respectively. Subacute thrombosis occurred in 2 patients (2.1%) in the total group compared with 9 patients (1.3%) in the subtotal group (p = 0.63). Angiographic restenosis occurred in 27% vs 22% (p = 0.40) and repeat angioplasty in 15% vs 13% (p = 0.62) in the total and subtotal groups, respectively. Thus, coronary stenting of chronic total occlusions after successful recanalization could be performed with a high success rate. In addition, the incidence of stent thrombosis, angiographic restenosis, and the need for target lesion revascularization is comparable to that of an unselected cohort of patients with nonocclusive stenoses.

Aged↗
PubMed1998

Low restenosis rate in lesions of the left anterior descending coronary artery with stenting following directional coronary atherectomy.

The present study evaluated acute and late results with stenting following directional coronary atherectomy (DCA) for the lesions in the left anterior descending coronary artery (LAD). Between April 1995 and January 1997, 200 LAD lesions with > or =3 mm reference vessel diameter were treated with coronary stents. The lesions were divided as to whether or not DCA was performed before stenting; 1) stenting alone (n = 163) and 2) debulking and stenting (n = 37). There were no significant differences in the incidences of complications except for non-Q-wave myocardial infarction that was more frequent in patients with debulking and stenting than in those with stenting alone (13.5% vs. 2.4%, P < 0.05). A greater acute lumen gain (2.85 +/- 0.66 vs. 2.25+/-0.60 mm, P < 0.01) and minimal lumen diameter (3.64+/-0.56 vs. 3.15+/-0.41 mm, P < 0.01) after stenting were observed in patients with debulking and stenting than in those with stenting alone. At follow-up patients with debulking and stenting continued to have a greater minimal lumen diameter (2.88+/-0.72 vs. 2.15+/-0.85 mm, P < 0.01) and had a lower restenosis rate (6.3% vs. 23.1%, P < 0.05) than those with stenting alone. Stenting following DCA appears to be advantageous in the LAD lesions with > or =3 mm reference vessel diameter.

Aged↗
PubMed1998

Procedural and follow up results with a new balloon expandable stent in unselected lesions.

OBJECTIVE: To assess the clinical and angiographic results of the first clinical application of a new balloon expandable stent, the NIR stent, characterised by high longitudinal flexibility and low profile before expansion, and by high radial support and minimal recoil and shortening after expansion. DESIGN: Single centre survey of unselected lesions in consecutive patients. SETTING: Tertiary referral centre. PATIENTS AND LESIONS: 93 stents of various length (9, 16, and 32 mm) were implanted in 64 lesions in 41 patients. Twenty lesions (31%) were longer than 15 mm, and 17 lesions (27%) were located in vessels with a diameter smaller than 2.5 mm. Extreme tortuosity of the proximal vessel was present in 15 lesions (23%). All patients were treated with aspirin and ticlopidine. All lesions were evaluated before and after treatment by quantitative angiography, and in 47 lesions (75%) the stent expansion was also controlled by intracoronary ultrasound. Clinical follow up was available in all patients and angiographic follow up was performed in 53 lesions (84%), at a mean (SD) interval of 5.4 (1.7) months. RESULTS: Deployment of the stent failed in two lesions (3%). Minimum lumen diameter increased from 1.01 (0.54) mm to 2.94 (0.49) mm, and diameter stenosis decreased from 66(15)% to 7(11)%. There was one in-hospital non-Q wave myocardial infarction, one sudden death after 40 days, and 17 target lesion revascularisations (27%). Angiographic restenosis (> or = 50% diameter stenosis) was documented in 19 lesions (36% of all lesions with angiographic follow up), with an average residual diameter stenosis of 43(21)% and minimum lumen diameter of 1.63 (0.74) mm. Restenosis was more common in vessels with a reference diameter < 2.5 mm (45%) and for lesions longer than 15 mm (46%). CONCLUSIONS: The NIR stent could be used successfully in most lesions, achieving optimal angiographic results with very few in-hospital or subacute cardiac events. The angiographic restenosis rate and need for target lesion revascularisation remained high in this unfavourable lesion subset, especially in small vessels and long lesions.

Catheterization↗