Abderrahman Machraoui

Acute and chronic tissue response to coronary stent implantation: pathologic findings in human specimen.

OBJECTIVES The aim of our study was to analyze the cellular components of neointimal tissue regeneration after coronary stenting. BACKGROUND High restenosis rates are a major limiting factor of coronary stenting. To reduce the occurrence of restenoses, more insights into the mechanisms leading to proliferation and expression of extracellular matrix are necessary. METHODS Twenty-one autopsy cases with coronary stents implanted 25 h to 340 days before death were studied. The stented vessel segments were analyzed postmortem by light microscopy and immunohistochemical staining. RESULTS In the initial phase stents are covered by a thin multilayered thrombus. Alpha-actin-positive smooth muscle cells (SMCs) are found as the main cellular component of the neointimal tissue. Later (>6 weeks) extracellular matrix increases and fewer SMCs can be found. In every phase the SMC layers are loosely infiltrated by inflammatory cells (T lymphocytes). In the early postinterventional phase all endothelial cells are destroyed. The borderline between the vessel lumen and the vascular wall is constituted by a thin, membranous thrombus. Six weeks after stenting, SMCs form the vessel surface. Complete reendothelialization is first found 12 weeks after stenting. CONCLUSIONS Stent integration is a multifactorally triggered process with proliferating SMCs generating regenerative tissue. In the early phase predominantly thrombotic material can be observed at the site of stenting, followed by the invasion of SMCs, T lymphocytes and macrophages. The incidence of delayed reendothelializations and the occurrence of deep dissections may be associated with excessive SMC hyperplasia.

SEGMENTATION OF 3D INTRAVASCULAR ULTRASONIC IMAGES BASED ON A RANDOM FIELD MODEL

Segmentation of intravascular ultrasound images provides important information about the degree of vessel obstruction as well as about the shape and size of plaques. To address the problems of inter- and intra-observer variances associated with conventional manual tracing, a fully automated segmentation was developed. The algorithm is based on the optimisation of a maximum a posteriori estimator, implementing the Rayleigh distribution of speckle and a priori information about the contours. Within 3D image sets, additional information by the blood flow resulting in a decorrelation of the pixels within the luminal boundary is used to initialise the segmentation. To accelerate the estimation, dynamic programming was used. The segmentation algorithm was realised as a Windows 95 application on a Pentium II/233 MHz and delivered reliable and reproducible results independent of the catheter position and the total image brightness (except overflow). In contrast, contours drawn by two physicians for an evaluation of 29 clinical cases showed large intra- and inter-observer variances. In vivo images were acquired with a 20 MHz transducer array (EndoSonics InVision). Comparison with the contours drawn by the physicians and histology demonstrates the potential of the segmentation algorithm.

Aerobic Capacity in Rate Modulated Pacing

Whether heart rate or AV synchrony is the most important factor for an increase in aerobic capacity was evaluated in a comparative study between sinus bradycardia, VVIR, DDD, and DDDR stimulation. Sixteen patients (mean age 67 years) with chronotropic incompetence and impJanted DDDR pacemaker (Telectronics META 1250) were randomly studied by cardiopulmonary exercise testing. All patients were exercised to their anaerobic threshold (ATJ with the following heart rates: DDD 84 ± 3, WIR 110 ± 5, and DDDR 116 ± 6 beats/min. Mean oxygen uptake (VO2, mL/kg per min) at AT was 7.4 ± 0.3 in DDD and WIR modes. A 12% increase was measured in DDDR mode (8.3 ± 0.4). Compared to VVIR work capacity in the DDDR mode was improved by 17% (41 vs 48 W/min). In patients with isolated sinus node disease (n = 9) the increase of VO2 and work capacity at AT during DDDR mode was more pronounced (16% and 20%, respectively, compared to VVIR). In patients with intermittent second or third degree AV block (n = 7) the differences between the pacing modes were not significant. This might partly be due to a lesser degree of chronotropic incompetence in this subgroup. In conclusion only the conjunction of heart rate increase and preservation of AV synchrony provides a significant improvement in aerobic capacity during exercise.

Hyperfibrinogenemia increases the risk of cardiac events after coronary artery stenting

Abstract Primary success rates, and the angiographic and clinical outcome after percutaneous coronary intervention, are influenced by many different factors. Clinical features and morphologic characteristics of the target lesion are important. Also, interventionally caused endothelial trauma may trigger atherogenetic and procoagulatory factors leading to intraluminal thrombosis. The study population consisted of 228 consecutive, unselected patients with symptomatic coronary artery disease or exercise-induced myocardial ischemia and coronary artery stenoses eligible for percutaneous intervention. We analyzed different clinical, morphological, and laboratory (total cholesterol, high-density lipoprotein-cholesterol, low-density lipoprotein-cholesterol, triglycerides, fibrinogen) features in those patients with adverse cardiac events (stent thrombosis, myocardial infarction, urgent target vessel revascularization, death) after primary successful coronary artery stenting, compared with a control group without adverse events. In the group with adverse cardiac events we found a significantly higher level of fibrinogen compared with the control group. Other laboratory data and clinical characteristics were not significantly different between the two groups. The study shows a possible association between hyperfibrinogenemia and adverse cardiac events after intracoronary stenting. In clinical practice, the potential role of elevated levels of fibrinogen in an unfavorable outcome after percutaneous coronary interventions should be considered when planning coronary artery stenting.

Comparison of the efficacy and safety of aspirin alone with coumadin plus aspirin after provisional coronary stenting: final and follow-up results of a randomized study.

BACKGROUND The antithrombotic benefit of the conventional treatment with coumadin after coronary stenting is limited by bleeding complications. However, the superiority of an antiplatelet therapy with aspirin alone compared with coumadin plus aspirin has not been proven by randomized studies. The efficacy and safety of treatment with aspirin alone in comparison to coumadin plus aspirin were evaluated in this randomized study. METHODS Out of 164 patients aged 59.7 +/- 9.2 years, 79 patients were randomly assigned to receive 100 mg aspirin daily (group A) and 85 patients randomly assigned to coumadin plus aspirin (group CA) after provisional coronary stenting with a high-pressure technique. The primary end point was defined as the absence of death, subacute closure of the target vessel, myocardial infarction, urgent coronary bypass surgery, repeated coronary angioplasty, and peripheral vascular complications requiring transfusion or surgery. High-pressure inflation technique was used, but ultrasound guidance was not. RESULTS During hospitalization (median 8 days), 135 patients (82. 3%) were free of events (A, 84.8%; CA, 80.8%; P =.42). Eleven (6.7%) subacute closures occurred (A, 10.1%; CA, 3.5%; P =.09); 2 of them were lethal in the aspirin group. Emergency bypass surgery was performed in 1 patient in each group. Peripheral vascular complications were observed in 13 patients (7.9%) (A, 1.3%; CA, 14. 1%; P <.01). At 3-month follow-up, 15 (9.1%) elective revascularization procedures (A, 7.6%; CA, 10.6%; P =.51) were performed. CONCLUSION Aspirin alone at the low dose of 100 mg administered or the combination of coumadin and aspirin after high-pressure coronary stenting does not prevent adverse clinical events when ultrasound guidance is not used.

Two-Dimensional Echocardiographic Assessment of Right Cardiac Pressure Overload in Patients with Chronic Obstructive Airway Disease

Two-dimensional echocardiography was used to estimate right cardiac pressure overload in patients with chronic obstructive airway disease. Area measurements of the four heart chambers were carried out from the apical four-chamber view. Additionally, the respiratory behaviour of the inferior vena cava was examined from the subcostal view. A good apical imaging of the four-chamber view for area measurement was obtained in 44 out of 48 patients with chronic obstructive airway disease. The respiratory behaviour of the inferior vena cava was investigated from the subcostal view in 38 patients. Within 8 days after echocardiography, right cardiac catheterization was carried out in order to measure pulmonary artery and right atrial mean pressures and to determine pulmonary vascular resistance. A good correlation was found between pulmonary artery mean pressure and the following echocardiographic parameters: area index (area/body surface) of the two right heart cavities (r = 0.83), right-to-left ventricular area ratio (r = 0.82) and right-to-left cardiac area ratio (ratio between the added areas of both right heart cavities on the one side and the added areas of both left heart cavities on the other; r = 0.82). Correlation between these parameters and pulmonary vascular resistance (r = 0.71, 0.66 and 0.71, respectively) and between the right atrial mean pressure and the right atrial area index was less close (r = 0.64). On the other hand, the respiratory behaviour of the inferior vena cava proved to be highly specific but not very sensitive in predicting a pathological right atrial pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical and angiographic results of coronary artery stenting using PURA-VARIO (PUVA) stents

BACKGROUND: Many different stent types are available for intracoronary placement. No clinical trial has demonstrated clearly the superiority of any stent design over another. METHODS: This study was designed to analyze clinical and angiographic results after using intracoronary PURA-VARIO (Devon Medical, Hamburg, Germany) (PUVA) stents. A total of 306 implanted stents were investigated in a series of 217 unselected patients (61.2 ± 10.7 years, 74.3% male). Stenting was performed electively and during acute coronary syndromes. Stents were manually mounted on angioplasty balloons and expanded in the target lesion. Angiographic measurements were carried out by quantitative coronary angiography. RESULTS: Stenting was successful in 214/217 patients (98.8%). During hospitalization (median three days) 206 patients (94.9%) were free from adverse cardiac events. Stent thrombosis occurred in five patients (2.3%), Q-wave infarction in one (0.5%) and urgent percutaneous target vessel revascularization in four (1.8%). Follow-up angiography, performed in 170 patients (78.3%) showed a restenosis (≥50% diameter stenosis) in 44/170 patients (25.9%), requiring angioplasty in 29 (17.2%). A surgical revascularization was recommended in 13 patients (7.6%). One patient died during follow-up from an unknown cause; however, sudden cardiac death was most likely. CONCLUSIONS: PUVA stents are characterized by a high level of safety and efficacy. Clinical and angiographic results are comparable with those of other approved stents. (Int J Cardiovasc Intervent 2003; 5: 156-160)

fla@@@Problematik der klinischen Einschätzung der Ruhe- und Belastungshämodynamik bei chronisch Herzkranken@@@Prediction of hemodynamics at rest and during exercise in patients with chronic heart diseases: Zur Wertigkeit der Einschwemmkatheterisierung und Problematik klinischer Klassifikation

□ BackgroundNYHA classification is mostly used for graduation of clinical limitation due to cardiac failure. Right heart catheterization is not generally used to evaluate hemodynamics and to define the effects of drugs in patients with chronic cardiac failure. Clinical data and results from echocardiography, stress tests or nuclear cardiology seem to be sufficient. Our aim was to demonstrate subjectivity of a classification system (NYHA) comparing the graduation done by physicians and by patients and to represent the difficulty to prognosticate hemodynamic data of patients with heart failure.□ Patients and MethodsLimitation of 53 patients with heart diseases was classified by physicians and patients using NYHA classification. Pulmonary capillary wedge pressure (PCWP), stroke volume (SV) and cardiac output were predicted by physicians; they were allowed to utilize all examination data they could get. Predicted hemodynamic data were compared with the results of measurement at rest and during exercise.□ ResultsPatients classified themselves significantly worse than physicians did: 2.68±0.64 vs. 2.23±0.74 (p=0.0012). Similarity in NYHA classification was found in 29/53 cases. Correlation of predicted and measured hemodynamic data was low: PCWP (at rest) r=0.346; PCWP (during exercise) r=0.232; SV (at rest) r=0.476; SV (during exercise) r=0.445; HMV (at rest) r=0.412; HMV (during exercise) r=0.538.□ ConclusionClinical classification systems like NYHA are subjective, classification by physicians differs significantly from classification by patients. Prediction of hemodynamics is not possible despite all examination data had been available. Right heart catheterization is necessary to define hemodynamics at rest and during exercise.BACKGROUND NYHA classification is mostly used for graduation of clinical limitation due to cardiac failure. Right heart catheterization is not generally used to evaluate hemodynamics and to define the effects of drugs in patients with chronic cardiac failure. Clinical data and results from echocardiography, stress tests or nuclear cardiology seem to be sufficient. Our aim was to demonstrate subjectivity of a classification system (NYHA) comparing the graduation done by physicians and by patients and to represent the difficulty to prognosticate hemodynamic data of patients with heart failure. PATIENTS AND METHODS Limitation of 53 patients with heart diseases was classified by physicians and patients using NYHA classification. Pulmonary capillary wedge pressure (PCWP), stroke volume (SV) and cardiac output were predicted by physicians; they were allowed to utilize all examination data they could get. Predicted hemodynamic data were compared with the results of measurement at rest and during exercise. RESULTS Patients classified themselves significantly worse than physicians did: 2.68 +/- 0.64 vs. 2.23 +/- 0.74 (p = 0.0012). Similarity in NYHA classification was found in 29/53 cases. Correlation of predicted and measured hemodynamic data was low: PCWP (at rest) r = 0.346; PCWP (during exercise) r = 0.232; SV (at rest) r = 0.476; SV (during exercise) r = 0.445; HMV (at rest) r = 0.412; HMV (during exercise) r = 0.538. CONCLUSION Clinical classification systems like NYHA are subjective, classification by physicians differs significantly from classification by patients. Prediction of hemodynamics is not possible despite all examination data had been available. Right heart catheterization is necessary to define hemodynamics at rest and during exercise.

Value of lesion morphology and of residual stenosis in predicting late clinical outcomes and restenosis rate post-PTCA in single-vessel disease

The study assessed an impact of stenosis morphology before coronary angioplasty (PTCA) and of residual diameter stenosis after the procedure on major adverse cardiac events and restenosis rate at 1 year after intervention in single-vessel disease. Visual analysis of stenoses, using the ABC lesion score system and on-line quantitative evaluation (ACA, DCI, Philips), was performed in 70 patients undergoing PTCA. Recurrence of angina at rest and/or positive treadmill exercise test (TET) ⩾6 weeks after PTCA and/or major cardiac events were considered as evidence of restenosis. At 1 year follow-up 56 patients (80%) were event free, without angina at rest and without positive TET, with residual diameter (RD) after PTCA a mean of 2.00±0.48 mm. In the restenosis group (n=14) RD was a mean of 1.58±0.43 mm (p<0.01): there were three patients with angina at rest, five with Positive TET, and six with cardiac events. In this group, one-half of the stenoses was in class C of the lesion. Residual diameter stenosis, measured objectively after balloon angioplasty, and evaluation of lesion morphology before PTCA can predict late clinical outcomes after the procedure in single-vessel disease.