Effect of a dihydropyridine-type calcium channel blocker on vascular remodeling after experimental balloon angioplasty

OBJECTIVE

Aim of the study was to evaluate the influence of the dihydropyridine derivative BW 9798 on intimal hyperplasia in a carotid artery injury model of New Zealand White rabbits on a high cholesterol diet.

METHODS

In carotid arteries of 50 New Zealand White rabbits atherosclerotic lesions were induced by cholesterol diet and electrostimulation of the artery. In 40 animals the resulting primary lesion was subjected to balloon angioplasty (BA). Three days prior to BA animals received BW 9798 or placebo per os until sacrifice three days or 28 days after BA.

RESULTS

BW 9798 lead to increased cross sectional area by 128.3% and an increased luminal area by 157% after 28 days after BA compared with placebo. However the degree of stenosis did not significantly decrease. The cell count of the different layers of the arteries decreased by 64.5% in the intima and by 62.6% compared with placebo treated animals after BA. Additionally the number of smooth muscle cell (SMC) layers in the neointima was significantly lower in BW 9798 treated animals than in placebo animals (8±3 vs 14±9, p<0.05) although the proliferation was not changed by BW 9798 treatment 3 days after BA.

CONCLUSION

BW 9798 leads to significant changes in vessel wall geometry although the influence on vascular remodeling of this compound is unclear. It can be speculated that the compound affects the homeostasis of extracellular matrix, invasion of inflammatory cells into the vessel wall and the expression of cytokines. However, further investigation needs to clarify the role of BW 9798 on remodelling after BA.

Multislice computed tomography coronary angiography in patients admitted with a suspected acute coronary syndrome

OBJECTIVES

The aim of this prospective clinical study was to assess the accuracy and clinical relevance of multislice computed tomography coronary angiography (MSCTCA) in patients presenting with acute chest pain.

BACKGROUND

Multislice computed tomography coronary angiography has shown ability to detect accurately coronary artery disease (CAD) in selected elective patient groups.

METHODS

One hundred and twenty patients presenting with acute chest pain (<24 h) underwent MSCTCA (Siemens Sensation 16) before a scheduled inpatient conventional coronary angiogram (CCA). Exclusion criteria included patients with STEMI, non-sinus rhythm, contraindication to beta blockers and renal impairment. Blinded visual assessment of MSCTCA to detect CAD was performed on an 11-segment model. The accuracy of MSCTCA was compared to CCA to detect significant stenoses (> or =50%).

RESULTS

One hundred and thirteen patients underwent both investigations. The prevalence of significant CAD was 74%. 1,243 native segments were assessed by MSCTCA. The overall ability of MSCTCA to detect the presence of > or =1 significant stenosis in all native segments had a sensitivity of 92% (95%CI 83-97%), specificity of 55% (95%CI 35-74%), positive predictive value of 86% (95%CI 76-93%) and negative predictive value of 70% (95%CI 47-87%). 22% of all segments (mostly distal) were non-analyzable. Coronary calcification was a major cause of false positivity.

CONCLUSION

In a prospective study of unselected patients presenting with acute chest pain, the diagnostic accuracy of 16-slice CT coronary angiography was moderate and less than reported from studies in elective patients. The clinical relevance of this technology to screen patients with acute chest pain is limited.

An update on clinical and pharmacological aspects of drug-eluting stents

The introduction of stents to clinical practice was the major breakthrough in the field of percutaneous coronary intervention. The introduction of stents was associated with two serious complications, the first was increase in subacute thrombosis within the first 30 days of stent implantation later controlled with the use of high pressure inflation and dual antiplatelet therapy, the second was the phenomenon of in-stent restenosis that was primarily caused by smooth muscle proliferation. While coronary stenting eliminates elastic recoil, it is unable to inhibit excessive neointimal formation. Stents were associated with an increase of neointimal formation compared to balloon angioplasty as a result of excessive injury to the vessel wall and the inflammatory process from interaction of metal with vessel wall. Local delivery of the potential agents for inhibition of neointimal formation to the site of the lesion was considered the desired approach. Several compounds have been tested for stent coating, primarily with the aim of the inhibition of SMC proliferation. Recently, new stents have emerged which are loaded with anti-inflammatory, anti-migratory, anti-proliferative or pro-healing drugs. In this review article the results of clinical studies investigating drug-eluting stents are discussed from pharmacological and clinical points of view, reviewing the current literature and the future prospective.

Short- and long-term effects of cytochalasin D, paclitaxel and rapamycin on wall thickening in experimental porcine vein grafts

OBJECTIVES

Neointima formation and wall thickening caused by smooth muscle cell proliferation compromise long-term patency of human aorto-coronary vein-grafts. We investigated short- and long-term effects of anti-proliferative pharmacological agents on experimental pig vein-grafts with similar dimensions and kinetics to human coronary grafts.

METHODS AND RESULTS

Saphenous veins were treated for 1 h ex vivo with vehicle or concentrations of cytochalasin D, paclitaxel or rapamycin found to be anti-proliferative in preliminary studies. Vehicle and treated veins were implanted contralaterally, end-to-end into the carotid arteries of pigs. Cytochalasin D 2.5 mug/ml non-significantly reduced neointima formation in 4-week vein-grafts (mean+/-standard error, 2.5+/-0.6 vs. 3.3+/-0.6 mm2, n = 10, p = NS), whilst paclitaxel 10 microM produced significant inhibition (1.7+/-0.2 vs. 3.0+/-0.3 mm2, n = 8, p < 0.01) as did rapamycin 0.1 mg/ml (0.6+/-0.3 vs. 1.7+/-0.5 mm(2), n = 8, p < 0.02). Similar effects were found on total wall cross-sectional area but medial area was unaffected. PCNA staining of 1-week vein grafts confirmed in vivo anti-proliferative effects of paclitaxel (21+/-2 vs. 36+/-3%, n = 5, p < 0.01) and rapamycin (32+/-1 vs. 57+/-6%, n = 6, p < 0.005); neither agent stimulated loss of endothelium at these concentrations. Neointima and total wall area increased significantly between 4- and 12-weeks in all vein-grafts such that there was no longer a significant effect on neointima formation of either paclitaxel (7.5+/-1.3 vs. 8.9+/-1.9 mm2 in control, n = 5, p = NS) or rapamycin (6.0+/-0.9 vs. 7.9+/-1.1 mm2 in control, n = 9, p = NS) or on total wall area in 12-week grafts.

CONCLUSIONS

Pre-treatment of saphenous vein with anti-proliferative agents paclitaxel or rapamycin reduced neointima and total wall area after 4 weeks but continued growth abolished differences by 12 weeks. These results may help to understand the failure of clinical studies using anti-proliferative treatments in vein-grafts.

Comparison of radiation doses from multislice computed tomography coronary angiography and conventional diagnostic angiography

OBJECTIVES

The aim of this study was to quantify and compare effective doses from conventional angiography and multislice computed tomography (MSCT) coronary angiography using a 16-slice scanner.

BACKGROUND

Multislice computed tomography is now a viable modality for cardiac imaging. However, for any diagnostic use of ionizing radiation, the risk to the patient must be considered and justified.

METHODS

Multislice computed tomography angiography and conventional angiography were used to assess 180 patients with suspected coronary artery disease. Estimates of effective dose were derived from exposure data recorded for each patient examination. For each modality, a comparable calculation technique was used, based on Monte Carlo modeling of the standard Cristy phantom.

RESULTS

In a subset of 91 directly comparable patients the mean effective dose for MSCT coronary angiography was 14.7 mSv (SD 2.2) and that for conventional angiography was 5.6 mSv (SD 3.6). A significant difference in effective dose was seen between the two protocols.

CONCLUSIONS

The mean effective dose for MSCT coronary angiography was significantly higher than that for conventional angiography. As MSCT cardiac scanners become increasingly available, operators must be aware of the radiation dose and the factors that affect it.

The future of drug eluting stents

In-stent restenosis (ISR) is the major drawback of percutaneous coronary interventions, occurring in 10-40% of patients. Drug eluting stents (DES) are successful in a large majority of patients in preventing restenosis for the first year after implantation. Recently, new stents have emerged that are loaded with anti-inflammatory, antimigratory, antiproliferative, or pro-healing drugs. These drugs are supposed to inhibit inflammation and neointimal growth and subsequently ISR. The future of DES lies in the development of better stents with new stent designs, better polymers including biological polymers and biological biodissolvable stent coatings, and new, better drugs.

Stent-Based Delivery of Tissue Inhibitor of Metalloproteinase-3 Adenovirus Inhibits Neointimal Formation in Porcine Coronary Arteries

BACKGROUND

Stent-based antiproliferative therapy appears to decrease in-stent restenosis. However, alternative approaches might produce equivalent efficacy with better long-term safety. In previous work, an adenovirus capable of expressing the tissue inhibitor of metalloproteinase-3 (RAdTIMP-3) inhibited neointima formation in cell cultures and porcine saphenous vein grafts. RAdTIMP-3 decreased smooth muscle cell migration, stabilized the extracellular matrix, and uniquely promoted apoptosis. The current study developed eluting stent technology to deliver RAdTIMP-3 during stenting of pig coronary arteries.

METHODS AND RESULTS

Binding of virus to and elution from stents and transduction of pig coronary arteries were confirmed using beta-galactosidase as a reporter gene in vitro and in vivo. Deployment of RAdTIMP-3-coated stents increased apoptosis and reduced neointimal cell density, but did not increase inflammation or proliferation compared with beta-galactosidase-expressing adenovirus (RAdlacZ). Neointimal area after 28 days was significantly reduced to 1.27+/-0.19 mm2 with RAdTIMP-3 versus 2.61+/-0.31 mm2 with RAdlacZ stents (P<0.001) and 2.12+/-0.20 mm2 with bare stents (P<0.005).

CONCLUSIONS

Our results demonstrate for the first time to our knowledge the feasibility of adenovirus-coated stent technology and highlight the potential of TIMP-3 to produce significant inhibition of in-stent neointima formation.

Effects of atorvastatin on in-stent stenosis in normo- and hypercholesterolemic rabbits

BACKGROUND

In-stent stenosis is characterized by a prolonged proliferation and inflammatory reactions around the stent struts. Potentially the antiproliferative and lipid-lowering effects of atorvastatin can synergistically limit neointima formation after stenting.

METHODS

Palmaz-Schatz stents were placed in the iliac arteries of white New Zealand rabbits. One half of the animals was fed an 0.5% hypercholesterolemic diet, the other half was normocholesterolemic. Both groups received either atorvastatin (3 mg/kg bodyweight) daily or placebo (n=10 each in the four groups). After 28 days the segments were excised.

RESULTS

Injury scores as a result of vessel trauma induced by stent-overstretch injury differed significantly between the four groups (median 1.0-1.9) and the stent-induced injury outweighed the beneficial effects of statin therapy on neointima formation by far. Smooth-muscle-cell proliferation was significantly increased in both hypercholesterolemic groups. Intimal and medial proliferation as well as inflammatory infiltrates around the stent strut were reduced by 20-40% in animals that received statin therapy although the injury score in both statin groups was 19 and 60% higher than in control animals.

CONCLUSION

Thus, the data of this study indicate that smooth muscle cell proliferation and inflammation in stented vessels can be reduced by atorvastatin both in hypercholesterolemic rabbits and in animals with normal lipid levels.

Effects of local all-trans-retinoic acid delivery on experimental atherosclerosis in the rabbit carotid artery

BACKGROUND

Retinoids regulate a variety of biological processes and play an important role in cell differentiation and proliferation. All-trans retinoid acid (atRA) is known to inhibit smooth muscle cell growth and thus is supposed to have favorable effects on the incidence of restenosis after percutaneous coronary interventions. The broad biological spectrum, however, leads to numerous severe side effects which limit the clinical use of a systemic application of atRA. In order to avoid systemic side effects, local delivery of atRA is preferable. The aim of this study was to evaluate the effects of atRA on the response to injury in a second-injury model of experimental balloon angioplasty.

METHODS

After induction of a fibromuscular plaque in the right carotid artery of 40 New Zealand rabbits, 35 animals underwent balloon angioplasty of the preformed plaque formation. Subsequent local atRA delivery (10 ml, 10 microM) with the double-balloon catheter was performed in 15 animals. Five animals received vehicle only as sham controls, and five animals were solely electrostimulated, 15 animals served as control group with balloon angioplasty only. Vessels were excised 7 days (n=15) and 28 days (n=30) after intervention. Immunocytochemistry with antibodies against smooth muscle alpha-actin and myosin, bromodeoxyuridine, macrophages, collagen I and III and von Willebrand factor was performed. Quantitative analysis was done by computerized morphometry.

RESULTS

After local atRA delivery in vivo, the extent of stenosis was markedly reduced with 21.7+/-8.3% (mean+/-S.D.) 4 weeks after intervention compared to 31.8+/-13.4% in balloon-dilated animals (P=0.0937). Both a reduced early neointimal proliferation (P=0.0002) and an increase in overall vessel diameter (4 weeks after intervention, P=0.0264) contributed to a limitation of restenosis in atRA-treated animals. Immunocytochemistry revealed a more intense alpha-actin staining pattern after local atRA therapy indicating redifferentiating effects of atRA on vascular smooth muscle cells.

CONCLUSIONS

Local delivery of atRA led to limitation of restenosis formation in this animal model. The concept of a local atRA therapy might be a promising way to exploit the potential of atRA for vascular indications while minimizing the severe side effects of systemic retinoid therapy.

Population need for coronary revascularisation: are national targets for England credible?

OBJECTIVE

To estimate the need for coronary revascularisation, by using an incidence of indications approach, among 45-84 year olds with stable angina, unstable angina, and acute myocardial infarction.

DESIGN

Modelling exercise. Six key steps along the pathway of care from initial diagnosis in primary or secondary care to revascularisation were defined and the frequency of indications estimated using routine data from hospital admissions and data from studies in the general population, and primary and secondary care.

SETTING AND PATIENTS

Mid-1998 population of England.

INTERVENTION

Coronary revascularisation.

MAIN OUTCOME MEASURE

Ability to benefit (need), defined by randomised trials, expert panel ratings from the ACRE (appropriateness of coronary revascularisation) study, or by informal consensus.

RESULTS

The need for coronary revascularisation was estimated to be 92 000 procedures, equivalent to a rate of 1861 per million population. Overall, the model of need exceeded current provision by 3.3:1, although among people aged 75 years and over the ratio was 7.7:1. A plausible upper estimate of need--obtained by assuming that 90% of patients with stable angina were referred from primary care and that angiography would be performed in 65% of patients with acute myocardial infarction and 75% of patients with unstable angina--was 2626 per million population.

CONCLUSIONS

The national target of 1500 revascularisation procedures per million population is credibly related to population need, although upper estimates of need are considerably higher. Better understanding is required of the benefits of referring patients with specific indications from primary care. The greatest relative increase in provision is required for those aged 75 and older, among whom trial evidence of benefit is scant.

Non-invasive coronary angiography with high resolution multidetector-row computed tomography. Results in 102 patients

AIMS

A new generation of multidetector-row CT (MDCT) scanners allows complete coronary coverage using retrospective ECG gating and 1mm slices. The purpose of this study was to investigate the potential of high resolution MDCT angiography with retrospective gating for detection of coronary artery stenoses.

METHODS AND RESULTS

A total of 102 patients underwent both conventional and MDCT coronary angiography. After intravenous injection of a non-ionic contrast medium the entire heart was scanned within a single breath hold using 1mm slices. All MDCT data sets were reconstructed with retrospective gating at 20% to 80% in increments of 10% relative to the cardiac cycle. Two blinded independent reviewers analysed image quality for segments 1-4 (right coronary artery), 5-8 (left main, left anterior descending), and 11, 12 (left circumflex). These segments were evaluated for the presence or absence of significant (>or=50%) stenoses. The results were compared with those of invasive coronary angiography in a blinded fashion. Overall sensitivity for the detection of significant stenoses (>or=50%) were 0.86 (reader 1) and 0.93 (reader 2), specificity 0.96 (reader 1) and 0.97 (reader 2), negative predictive value 0.98 (reader 1) and 0.99 (reader 2).

CONCLUSIONS

High resolution MDCT angiography with retrospective gating permits the non-invasive detection of coronary artery stenoses with high accuracy if image quality is optimized for each of the three major coronary arteries.

Low-molecular-weight heparin therapy for non-ST-elevation acute coronary syndromes and during percutaneous coronary intervention: an expert consensus

BACKGROUND

Therapy with either low-molecular-weight heparin (LMWH) or glycoprotein (GP) IIb/IIIa receptor antagonists is of benefit to patients with acute coronary syndromes (ACSs). However, algorithms that define how LMWH may be used in patients, proceeding from medical management to intervention and in conjunction with GP IIb/IIIa inhibitors, are lacking. The objectives of this task force were to formulate recommendations based on all available data for the use of LMWH, both with and without GP IIb/IIIa receptor antagonists, and to provide seamless integration of care during the transition from medical to interventional management.

METHODS AND RESULTS

An international task force of 14 cardiologists with extensive experience in clinical trials was convened in New York in February 2001 to address issues related to the use of LMWH in patients with non-ST-elevation ACS. Evidence from randomized trials, observational studies, and other reports was discussed, and consensus recommendations were formulated.

CONCLUSIONS

Substantial evidence exists that patients receiving LMWH for an ACS can safely undergo cardiac catheterization and percutaneous coronary intervention. Concerns regarding the transition of these patients from the medical service to the cardiac catheterization laboratory should therefore not impede the upstream use of LMWH. Furthermore, LMWH and GP IIb/IIIa receptor antagonists can be used safely in combination, with no apparent increase in the risk of major bleeding. Consensus algorithms for therapy are presented.

Occlusion versus shunting during MIDCAB: effects on left ventricular function and quality of anastomosis

BACKGROUND

Minimally invasive direct coronary artery bypass is an established clinical procedure for revascularization of the left anterior descending coronary artery. Mechanical stabilization and temporary occlusion is currently used to perform the anastomosis of the internal thoracic artery to the left anterior descending coronary artery. However, critical reduction of cardiac function can occur as a result of temporary ischemia. The purpose of this study was to evaluate whether ischemic sequelae can be avoided by using temporary intraluminal shunts and whether this alters early outcome.

METHODS

Thirty-five patients underwent minimally invasive direct coronary artery bypass revascularization using a mechanical stabilizer. In group A (n = 20), the anastomotic site was temporarily occluded by tourniquets. In group B (n = 15), temporary intraluminal shunts were inserted into the anastomotic site without any occlusion of the left anterior descending coronary artery. Anastomosis of the internal thoracic artery to the left anterior descending coronary artery was performed in an identical fashion. A Swan-Ganz catheter was inserted, and transesophageal echocardiographic measurements were obtained for analysis of left ventricular (LV) function. Regional wall motion, cardiac index, stroke volume index, systolic and diastolic LV diameters, and fractional area change were measured during four periods: at the start of the operation (baseline), placement of the stabilizer (stabilization), left anterior descending coronary artery occlusion (occlusion) or insertion of temporary intraluminal shunts (shunt), and 30 minutes after reperfusion (reperfusion). Angiograms were obtained 4 to 6 days postoperatively.

RESULTS

In group A, LV performance, cardiac index, stroke volume index, and fractional area change decreased during occlusion whereas systolic diameters increased. Almost two myocardial segments per patient developed severe hypokinesia in the perfusion area. These changes disappeared after 30 minutes of reperfusion, with increased LV function. In group B, LV function remained stable whereas hypokinetic wall motion was only detected in 2 patients. Early angiograms revealed 90% of the grafts were patent in group A versus 100% in group B. The need for percutaneous intervention during the first 6 months was 20% in group A versus 6.7% in group B.

CONCLUSIONS

The use of temporary intraluminal shunts resulted in reduced acute ischemia and revealed wall motion abnormalities and maintained LV function. Furthermore, this technique suggests an improvement of early graft patency and a lower reintervention rate within the first 6 postoperative months. Thus, use of temporary intraluminal shunts appears to be superior to the occlusion technique early after minimally invasive direct coronary artery bypass procedures.

Virtual coronary angioscopy using multislice computed tomography

BACKGROUND

With faster image acquisition times and thinner slice widths, multislice detector computed tomography (MSCT) allows visualisation of human coronary arteries with diagnostic image quality. In addition to conventional axial slices, virtual coronary angioscopies (VCA) can be reconstructed using MSCT datasets.

OBJECTIVE

To evaluate the feasibility of reconstructing VCA and to determine the clinical value of this new application in detecting atherosclerotic coronary artery lesions.

METHODS

Datasets obtained by contrast enhanced non-invasive coronary angiography using MSCT (Somatom VZ) were analysed from 14 consecutive patients. VCA were simulated in 14 coronary arteries (left anterior descending, n = 7; right coronary, n = 7). Lesion detection was undertaken on conventional contrast enhanced axial slices, as well as by VCA. Intracoronary ultrasound (ICUS) was used as the gold standard for in vivo plaque detection.

RESULTS

38 lesions were detected both on ICUS and on axial slices: 14 severe target lesions of > 75% area stenosis (11 calcified, three non-calcified), and 24 intermediate lesions of < or = 75% area stenosis (seven calcified, 17 non-calcified). Using VCA, all severe lesions (n = 14) and all calcified intermediate plaques (n = 7) could clearly be identified. However, non-calcified intermediate lesions (n = 17) could not be accurately distinguished from the vessel wall; they were recognised as vessel wall alterations without significant luminal narrowing.

CONCLUSIONS

Current MSCT technology allows reconstruction of VCA with good image quality. Despite a more anatomical view of heart and coronary vessels on three dimensional reconstruction, conventional axial slices were found to be superior for detecting coronary lesions. Thus further technical innovations are required before VCA can become a useful technique in clinical cardiology.

Influence of heart rate on vessel visibility in noninvasive coronary angiography using new multislice computed tomography: experience in 94 patients

OBJECTIVES

Initial reports indicate that coronary artery lesions might be visualized with high sensitivity and specificity by the use of recently introduced multislice computed tomography (MSCT). Current CT technology offers a temporal resolution of 250 ms. In case of heart rates (HRs) >65 beats/min (bpm), however, the reconstruction software switches from a single-phase algorithm (using data from one heart cycle only) to a biphase algorithm using image data of two consecutive heart cycles, improving temporal resolution to down to 125 ms. Thus, it was the aim of the present study to evaluate the influence of the patients' (pts) HR on image quality expressed by vessel segment visibility.

METHODS AND RESULTS

MSCT scans (Somatom VZ) were performed in 94 pts. Ten coronary segments were analyzed in each patient with regard to image quality (RCA: segments [sgts] 1-4, LMS: sgt 5, LAD: sgts 5-8, LCX: sgts 11, 12). A total of 697 of 940 (74.1%) sgts were accurately visualizable (RCA: 244/376 [64.9%], LMS: 94/94 [100%], LAD: 232/283 (82.3%), LCX: 146/188 [77.7%]). Beta-blocker therapy had a significant influence on mean HR (65 pts on beta-blocker, HR 65.1+/-10.7 bpm vs. 29 pts, HR 71.6+/-12.2 bpm, P=.01). A significant inverse correlation between HR and segmental visibility was found (r=-.48, P<.0001), with best visibility in pts with lower HRs (n=14 pts with 10 analyzable sgts, HR 60+/-10.1 vs. n=8 pts with 4 analyzable sgts, HR 79.9+/-6.9, P<.0001).

CONCLUSIONS

Our results indicate that vessel visibility is highly dependent on the pts HR. Best vessel visibility was found in pts with HR <65 bpm with single-phase image reconstruction. Thus, it appears to be advisable to evaluate, and if needed, to lower the pts HRs before undergoing MSCT coronary angiography in order to achieve best image quality.

Localized pericardial tamponade: difficult echocardiographic diagnosis of a rare complication after cardiac surgery

We report 2 cases of localized pericardial tamponade occurring soon after cardiac surgery, in which the diagnosis could not be made with transthoracic echocardiography. Computed tomography and transesophageal echocardiography, respectively, were necessary, and this underlies the importance of alternative imaging modalities when this condition is suspected. A high index of suspicion is crucial for reaching the correct diagnosis.

Local delivery of paclitaxel using the double-balloon perfusion catheter before stenting in the porcine coronary artery

Paclitaxel is a new cancer chemotherapeutic agent that has been approved for clinical use in patients with a variety of different cancers. Paclitaxel inhibits cell proliferation by an action on microtubules. The aim of this study was to evaluate the safety and efficacy of locally delivered paclitaxel after coronary stent implantation. A novel double-balloon perfusion catheter was used to deliver the drug locally in the pig coronary artery. Twenty-seven domestic pigs underwent stent implantation of the left anterior descending artery. In the treatment group (n = 11), paclitaxel (10 ml; 10 micromol/l) was delivered using the double-balloon perfusion catheter prior to stent implantation. The control group received stent implantation only (n = 16). The animals were sacrificed 4 weeks later. Vessels were perfusion-fixed and morphometric analysis was performed using conventional techniques. In addition, the extent of injury was determined at each stent-strut area. Correlation of local injury and neointimal thickness was evaluated by linear regression. Neointimal thickness (paclitaxel 1.0 +/- 0.4 vs. control 0.7 +/- 0.3 mm), neointimal area (paclitaxel 4.1 +/- 2.2 vs. control 2.4 +/- 1.1 mm(2)), and the lumen area (paclitaxel 2.1 +/- 1.9 vs. control 2.5 +/- 0.9 mm(2)) did not show significant differences between both groups. Medial area (3.3 +/- 2.3 vs. 1.6 +/- 0.4 mm(2)) was larger in the vessels treated with paclitaxel (P < 0.05). Linear regression failed to show any difference in the response to injury between the two groups. Local delivery of paclitaxel with the double-balloon-perfusion catheter did not reduce neointima formation following stent implantation in native pig coronary arteries.

Use of intravascular ultrasound to compare effects of different strategies of lipid-lowering therapy on plaque volume and composition in patients with coronary artery disease

BACKGROUND

We studied whether lipid-lowering therapy with atorvastatin (target LDL cholesterol [LDL-C] <100 mg/dL) compared with a moderate treatment regimen that used other lipid-lowering drugs led to a lesser progression of atherosclerosis and to different changes in plaque echogenicity in patients with coronary artery disease.

METHODS AND RESULTS

This study was a 12-month, open-label, randomized, multicenter trial, which used serial 3D intracoronary ultrasound to calculate plaque volume and plaque echogenicity. After transcatheter therapy, 131 patients were randomized (atorvastatin n=65, usual care n=66). The target plaque had to be a minor lesion (ie, a diameter stenosis of <50% on angiography). After 12 months, mean LDL-C was reduced from 155 to 86 mg/dL in the atorvastatin group and from 166 to 140 mg/dL in the usual care group. Mean absolute plaque volume showed a larger increase in the usual care group compared with the atorvastatin group (usual care 9.6+/-28.1 mm(3), atorvastatin 1.2+/-30.4 mm(3); P=0.191). The hyperechogenicity index of the plaque increased to a larger extent for the atorvastatin group than for the usual care group, with a significant treatment effect for the percent change (atorvastatin 42.2%, usual care 10.1%; P=0.021).

CONCLUSIONS

One year of lipid-lowering therapy to <100 mg/dL LDL-C most likely led to a slowdown of plaque growth of minor lesions. The significantly larger increase in plaque hyperechogenicity is most likely due to a change in plaque composition.

Noninvasive detection of coronary lesions by multislice computed tomography: results of the New Age pilot trial

The reliable noninvasive assessment of coronary artery disease would constitute an important step forward in clinical cardiology. The aim of the New Age pilot trial was to evaluate the diagnostic accuracy of multislice computed tomography (MSCT) in determining coronary lesions. As a gold standard for in vivo plaque detection, intracoronary ultrasound (ICUS) was used. Forty plaques were detected by ICUS in 15 target vessels (LAD, n = 8; RCA, n = 7) in patients assigned for ICUS-guided PTCA. Preinterventional MSCT was performed in all patients and the results were compared to ICUS with regard to lesion detection and quantification. According to ICUS results, the 40 plaques were divided into three groups: group I, mild lesions < 50% (n = 14; 44.36% +/- 5.77%); group II, intermediate lesions 50%-75% (n = 12; 59.18% +/- 9.39%); and group III, severe lesions > 75% (n = 14; 91.47% +/- 3.68%). All MSCT scans showed sufficient image quality for analysis. Thirty of 40 (75%) plaques were detected by MSCT in a first blinded session. After unblinding the ICUS results, the remaining 10 (25%) plaques could be identified. Lesion severity was classified correctly in 34 of 40 (85%) plaques. Plaque calcifications were diagnosed correctly in 16 of 19 (84.2%) plaques. Quantification of vessel size revealed a good correlation to the ICUS results (r(2) 0.68; P = 0.004). Noninvasive MSCT angiography showed good diagnostic accuracy with regard to lesion detection and quantification of vessel size. The overall good image quality, makes this new technology a promising modality, which might become an alternative diagnostic approach in patients with known or suspected coronary artery disease. Cathet Cardiovasc Intervent 2001;53:352-358.

Accuracy and reliability of quantitative measurements in coronary arteries by multi-slice computed tomography: experimental and initial clinical results

AIM

To evaluate the accuracy of non-invasive measurements within coronary arteries by multi-slice computed tomography (MSCT). We present experimental as well as clinical data.

MATERIALS AND METHODS

Silicon tubes simulating coronary arteries (outer diameter 6 mm, lumen diameter within stenotic area 2 mm) were used for experimental studies. Clinical data were derived from 15 patients in whom vessel diameters were assessed by MSCT, intracoronary ultrasound (ICUS) and quantitative coronary angiography (QCA). MSCT were performed in a Somatom Volume Zoom(trade mark)CT system (Siemens, Forchheim, Germany) at 2 collimated slice widths (2.5 mm, 1.0 mm).

RESULTS

Outer silicon tube diameters were overestimated by MSCT (6.56 mm +/- 0.32 mm). All measurements revealed significantly better results on 1.0 collimation compared to 2.5 mm collimation (outer diameter: 6.36 mm +/- 0.22 mm vs 6.76 mm +/- 0.27 mm, P < 0.0001; lumen diameters: 1.83 mm +/- 0.14 mm vs 1.51 mm +/- 0.19 mm, P < 0.0001). The comparison of vessel diameters within human coronary arteries revealed comparable results between ICUS and MSCT (4.89 mm +/- 0.67 mm vs 4.91 mm +/- 0.71 mm, P = 0.79, r = 0.79, P < 0.0001). QCA-measurements showed significantly lower results (3.67 +/- 0.71, P < 0.0001, r = 0.62, P < 0.001).

CONCLUSIONS

Experimental as well as initial clinical results indicate acceptable reliability and accuracy of quantitative measurements by MSCT, when using thin collimated slice widths. Partial volume effects lead to a systematic overestimation of vessel size. MSCT has the potential to become an important non-invasive diagnostic tool in patients with coronary artery disease.

Ultrasound guidance: technique and results of aggressive ultrasound-guided PTCA. The UPSIZE Pilot Trial

Stenting results in a larger lumen than conventional balloon angioplasty. This is the major determinant of a good acute and long-term result. In this non-randomised, single centre trial, intravascular ultrasound was used preinterventionally to guide the choice of the balloon size. The aim was to achieve a maximum lumen area with balloon angioplasty only. We included 346 patients with 360 lesions. The diameter of the external elastic lamina by intravascular ultrasound was 4.67 mm. A mean balloon size of 4.0 mm was chosen. The initial luminal gain was 1.82 mm, the lumen area post intervention was 6.6 mm(2). Dissections occurred frequently but the incidence of major adverse events was not increased. At one year follow-up, the overall event free survival was 81%. Target lesion revascularisation was performed in 34 patients (10%). An angiographic follow-up was available for 261 patients (76%). Restenosis (> 50% diameter Stenosis) was found in 21%. The results show, that ultrasound guidance of balloon angioplasty provides a means to achieve a large initial luminal gain without the routine use of stents. The acute and long-term results suggest that the approach is safe and efficient. The data compare favorably with similar studies using advanced intravascular diagnostic tools to guide the angioplasty procedure.

Inhibition of smooth muscle cell proliferation after local drug delivery of the antimitotic drug paclitaxel using a porous balloon catheter

Percutaneous transluminal coronary angioplasty is an accepted treatment for coronary artery disease. The major limitation, however, is the high incidence of restenosis which limits the long-term benefit of this intervention. Paclitaxel is a new antiproliferative agent that has generated considerable scientific interest since it was introduced in clinical trials in the early 1980s. Recent in vitro studies have shown that paclitaxel has considerable antiproliferative activity in human coculture systems. In the present study the efficacy of paclitaxel was investigated after development of an intimal plaque by electrical stimulation and additional cholesterol diet and subsequent balloon angioplasty in 63 New Zealand White rabbits. Local drug delivery of paclitaxel was accomplished in 30 rabbits with a porous balloon catheter (35 holes, hole diameter 75 microm, 2.5 mm catheter diameter). Paclitaxel was administered locally with 4 ml (solution 10(-5) mol/L) using an injection pressure of 2 atm. To study the extent of restenosis and morphological changes, the animals were sacrificed 7, 28 or 56 days after intervention. After staining procedures quantification of SMC proliferation, intimal macrophages and morphological analyses were performed. Paclitaxel plasma concentrations were measured using HPLC technique. One week after balloon angioplasty the arteries treated with local paclitaxel delivery showed an insignificant trend towards a reduction in intimal smooth muscle cell proliferation (untreated 8.4 +/- 4.9 % vs paclitaxel treated 2.4 +/- 2.4 %, p = NS). However, this resulted in a significant reduction of stenosis degree of 66 % 8 weeks after intervention compared to the untreated group (untreated 41 +/- 18 % vs paclitaxel treated 14 +/- 11 %, p = 0.005). In conclusion, locally delivered paclitaxel prevented neointimal thickening in the rabbit carotid artery after balloon angioplasty. Local paclitaxel treatment may therefore be a clinical option for the prevention of restenosis after coronary interventions. However, further preclinical studies have to prove long-term efficacy and safety.

Noninvasive detection and evaluation of atherosclerotic coronary plaques with multislice computed tomography

OBJECTIVES

The aim of the present study was to evaluate the accuracy in determining coronary lesion configuration by multislice computed tomography (MSCT). The results were compared with the findings of intracoronary ultrasound (ICUS).

BACKGROUND

The risk of acute coronary syndromes caused by plaque disruption and thrombosis depends on plaque composition rather than stenosis severity. Thus, the reliable noninvasive assessment of plaque configuration would constitute an important step forward for risk stratification in patients with known or suspected coronary artery disease. Just recently, MSCT scanners became available for general purpose scanning. Due to improved spatial and temporal resolution, this new technology holds promise to allow for differentiation of coronary lesion configuration.

METHODS

The ICUS and MSCT scans (Somatom Volume Zoom, Siemens, Forchheim, Germany) were performed in 15 patients. Plaque composition was analyzed according to ICUS (plaque echogenity: soft, intermediate, calcified) and MSCT criteria (plaque density expressed by Hounsfield units [HU]).

RESULTS

Thirty-four plaques were analyzed. With ICUS, the plaques were classified as soft (n = 12), intermediate (n = 5) and calcified (n = 17). Using MSCT, soft plaques had a density of 14 +/- 26 HU (range -42 to +47 HU), intermediate plaques of 91 +/- 21 HU (61 to 112 HU) and calcified plaques of 419 +/- 194 HU (126 to 736 HU). Nonparametric Kruskal-Wallis test revealed a significant difference of plaque density among the three groups (p < 0.0001).

CONCLUSIONS

Our results indicate that coronary lesion configuration might be correctly differentiated by MSCT. Since also rupture-prone soft plaques can be detected by MSCT, this noninvasive method might become an important diagnostic tool for risk stratification in the near future.

Loss of cyclin A and G1-cell cycle arrest are a prerequisite of ceramide-induced toxicity in human arterial endothelial cells

BACKGROUND

Ceramide is an important messenger of TNF- and lipid-induced apoptosis. We previously demonstrated the adverse effect of TNF in the process of reendothelialization as well as the dependence of its effect on cell-cycle regulation. The current study was designed to investigate the linkage between ceramide induced toxicity and growth arrest in human endothelial cells.

METHODS AND RESULTS

Cultured human arterial endothelial cells (HAEC) served as an in-vitro model to test the cellular effects of C2-ceramide (C2). C2-induced cell death in HAECs occurred time- and dose-dependently. The LD(50) in subconfluent cells was three times lower than in confluent cell layers (25 vs. 75 microM). C2 caused up to 70% inhibition of BrdU and [3H]thymidine incorporation at non-toxic concentrations as a result of G1 cell-cycle arrest. Downregulation of cyclin A and p21(Cip1/Waf1) protein expression was observed independently of C2-toxicity, while expression of other cell-cycle regulatory genes was not affected. Inhibition of cyclin A protein expression by sequence-specific antisense-oligonucleotides was paralleled by significant growth-inhibition. The protein phosphatase inhibitor okadaic acid induced endothelial cell proliferation, which was completely abrogated by C2. In contrast, aphidicolin-synchronized endothelial cells demonstrated elevated cyclin A levels along with 30% higher BrdU-incorporation and 70% less C2-toxicity. G1-arrested cells, however, showed significantly enhanced C2-toxicity, lack of cyclin A expression and induction of uncleaved caspase-3 (CPP32).

CONCLUSIONS

Ceramide abrogates endothelial cell proliferation independently of apoptosis or necrosis at low concentrations (<or=10 microM) through loss of cyclin A expression with subsequent G1 cell-cycle arrest. Synchronization of HAECs in S-phase with aphidicolin overcomes C2-induced G1-arrest and partially blocks ceramide toxicity. These findings demonstrate the dependence of ceramide toxicity on cell cycle regulation, suggesting a strong bidirectional relationship between cell-cycle control and cell death in vessel biology.

All-trans retinoic acid regulates proliferation, migration, differentiation, and extracellular matrix turnover of human arterial smooth muscle cells

OBJECTIVE

The vitamin-A derivative all-trans retinoic acid (atRA) is a potent regulator of cell growth, differentiation, and matrix formation of various cell types and plays an important role in embryogenesis. However, sparse data are available about its effects on human vessel diseases. Thus, we studied the effects of atRA on human arterial smooth muscle cell (haSMC) and endothelial cell (haEC) proliferation, migration, differentiation and extracellular matrix (ECM) turnover in mono- and transfilter cocultures.

METHODS

Effects of atRA on human arterial cells in monocultures were determined using cell counting assays, BrdU-ELISA and MTT-tests. In transfilter cocultures haSMC-growth was studied under the stimulatory effect of proliferating haEC. Using Northern blot analysis, effects of atRA on mRNA expression of ECM-proteins were examined while protein expression and activity of matrix metalloproteinases were determined by Western blotting and zymography.

RESULTS

atRA caused a dose dependent inhibition of haSMC-growth in monocultures (IC(50) at 0.022 microM) whereas haEC-growth was inhibited less potently (IC(50) at 97 microM). In addition, proliferation and migration of haSMC through a porous membrane were inhibited dose dependently by micromolar atRA-doses after non-stop and single dose application of atRA on the endothelial side of the complex transfilter coculture system. Immunostainings and Northern blotting demonstrated an enhanced alpha-smooth muscle actin and heavy chain myosin expression in haSMC after atRA-treatment. Whereas mRNA-expression of the glycoproteins thrombospondin-1 and fibronectin were decreased, collagen-1 mRNA expression was even slightly stimulated. Transcription of biglycan and TGF-beta1 were not influenced in a specific manner. Finally, protein expression and activity of the matrix metalloproteinases MMP-2 and MMP-9 were inhibited significantly by atRA.

CONCLUSIONS

atRA was found to be a potent inhibitor of both haSMC-proliferation and -migration, even in coculture with haEC releasing growth factors. In addition, redifferentiation, ECM synthesis and ECM degradation were regulated by atRA which also influence haSMC migration and intima formation. Thus, atRA-treatment seems to be a promising strategy for the inhibition of processes involved both in atherosclerosis and restenosis.

Alcohol enhances oxysterol-induced apoptosis in human endothelial cells by a calcium-dependent mechanism

Controversy exists about the net effect of alcohol on atherogenesis. A protective effect is assumed, especially from the tannins and phenolic compounds in red wine, owing to their inhibition of low density lipoprotein (LDL) oxidation. However, increased atherogenesis occurs in subjects with moderate to heavy drinking habits. The purpose of this study was to investigate the influence of alcohol in combination with oxysterols on the endothelium. Cultured human arterial endothelial cells (HAECs) served as an in vitro model to test the cellular effects of various oxysterols. Oxysterols (7beta-hydroxycholesterol, 7-ketocholesterol, and cholesterol-5,6-epoxides), which are assumed to be the most toxic constituents of oxidized LDL, induced apoptosis in HAECs through calcium mobilization followed by activation of caspase-3. Ethanol, methanol, isopropanol, tert-butanol, and red wine all potentiated oxysterol-induced cell death up to 5-fold, paralleled by further induction of caspase-3. The alcohol effect occurred in a dose-dependent manner and reached a plateau at 0.05% concentration. Alcohol itself did not affect endothelial cell viability, nor did other solvents such as dimethyl sulfoxide mimic the alcohol effect. So far as the physiologically occurring oxysterols are concerned, this effect was apparent only for oxysterols oxidized at the steran ring. The possibility of alcohol facilitating the uptake of oxysterols into the cell was not supported by the data from an uptake study with radiolabeled compounds. Finally, alcohol in combination with oxysterols did cause a dramatic increase in cytosolic calcium influx. Blockage of calcium influx by the calcium channel blocker aurintricarboxylic acid or the calcium chelator ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid abrogated the alcohol-mediated enhancement of oxysterol toxicity. We describe for the first time a mechanistic concept explaining possible adverse effects of alcohol in conjunction with physiologically occurring oxysterols on atherogenesis.

Primary cardiac leiomyosarcoma originating from the pulmonary valve. Case report and review of the literature

Primary cardiac tumours are rare findings (incidence 0.02% according to a recent meta-analysis) with dismal prognosis. Approximately 25% are malignant, mostly represented by sarcomas. Among these, leiomyosarcomas are exceptional. Treatment for primary cardiac leiomyosarcomas consists of radical surgical resection followed by adjuvant radiation therapy and/or chemotherapy. The mean survival after surgery and adjuvant therapies is 6.8 months. We present a rare case of a 40- year-old male patient with a primary cardiac leiomysarcoma originating from the pulmonary valve. This patient died after surgery and implantation of a homograft of the pulmonary trunk. Furthermore, the literature has been reviewed.

Cartilage oligomeric matrix protein (thrombospondin-5) is expressed by human vascular smooth muscle cells

Cartilage oligomeric matrix protein (COMP/thrombospondin [TSP]-5) belongs to the thrombospondin gene family and is an extracellular glycoprotein found predominantly in cartilage and tendon. To date, there is limited evidence of COMP/TSP-5 expression outside of the skeletal system. The aim of the present study was to investigate the expression of COMP/TSP-5 in cultured human vascular smooth muscle cells and human arteries. COMP/TSP-5 mRNA and protein expression was detected in cultured human vascular smooth muscle cells with both Northern blotting and immunoprecipitation. Serum, as well as transforming growth factor (TGF)beta1 and TGF-beta3, stimulated COMP/TSP-5 mRNA expression. COMP/TSP-5 was detected in normal as well as atherosclerotic and restenotic human arteries with immunohistochemistry. The majority of COMP/TSP-5 was expressed in close proximity to vascular smooth muscle cells. In vitro attachment assays demonstrated strong adhesion of smooth muscle cells to COMP/TSP-5-coated surfaces, with the majority of cells spreading and forming stress fibers. In addition, COMP/TSP-5 supported the migration of smooth muscle cells in vitro. The present study shows that COMP/TSP-5 is present in human arteries and may play a role in the adhesion and migration of vascular smooth muscle cells during vasculogenesis and in vascular disease settings such as atherosclerosis.

Influence of vessel size, age and body mass index on the flow-mediated dilatation (FMD%) of the brachial artery

BACKGROUND

The non-invasive determination of the endothelial dysfunction (ED) of the brachial artery is a widely used method in clinical research. It remained, however, unclear, whether the test-results are influenced by the anatomical vessel size, the patients age, body mass index (BMI) or gender.

METHODS

The flow-mediated vasodilatation (FMD%) of the brachial artery was determined in 122 consecutive (88 male, 34 female) patients. FMD% was measured using high resolution ultrasound (13 Mhz) at rest, during reactive hyperaemia and after the sublingual administration of glycerolnitrate (GTN%).

RESULTS

Lumen diameters at rest varied from 2.48 mm to 6.33 mm (4.46+/-0.74 mm). The extent of FMD% as well as of GTN% showed an inverse correlation to the resting lumen diameters (r=-0.33, P<0.001/r=-0.51, P<0.001). This correlation was even more distinct in females (females: FMD% r=-0.54, P<0.001; GTN% r=-0.64, P<0.001 vs. males: FMD% -0.23, P<0.001; GTN% -0.59, P<0. 001). No significant influence of age (61+/-9 years, FMD%: r=-0.04, P=0.68, GTN%: r=-0.18, P=0.05) and BMI (27.03+/-3.43 kg/m(2), FMD%: r=0.16, P=0.08, GTN%: r=0.09, P=0.3) on the test results were found.

CONCLUSIONS

FMD% was found to be rather independent of age or BMI. The anatomical vessel size had an influence on the test results, which was more obvious in female patients. Our data indicate the necessity of further methodological studies, in larger, community-based populations. In particular, it needs to be clarified, whether vessel size or even gender-specific correction factors are required when using this technique in routine clinical practice.

[Use of Abciximab in threatening vascular occlusion after PTCA]

The administration of GP IIb/IIIa antagonists has been shown to be effective in reducing myocardial infarction and cardial death when given before PTCA. This prospective study was performed to determine the efficacy of abciximab in a bail-out situation to manage threatened or acute vessel closure.

METHODS

Acute or threatened vessel closure was observed in 104 (5.5%) out of 1903 consecutive patients treated with PTCA in our institution. Of the 104 patients 46 (44%) were treated for unstable angina (CCS IV). Abciximab was administered in bail-out situations in a dosage of 0.25 mg/kg given as a bolus, which was followed by an intravenous infusion of 10 micrograms/min over 12 hours. Repeat PTCA was performed shortly after the administration of the abciximab bolus. After the procedure, the sheath was left in place and control angiography was carried out 24 h later.

RESULTS

In 100 of the 104 patients TIMI flow III could be restored by abciximab therapy and RePTCA. In 4 patients an additional stent implantation was necessary due to persistent flow limitation. One day post PTCA, early follow-up angiography demonstrated patency of all vessels except two. In-hospital events occurred in 4 patients. Three of these patients underwent emergency CABG due to subacute vessel closure a few hours after PTCA and died during or directly after surgery. Follow-up after one year included clinical status and control angiography of the target vessel. During long-term follow-up, MACE occurred in 15 patients (2 MI, 8 CABG and 5 RePTCA).

CONCLUSION

The results of this prospective trial demonstrate the efficacy of abciximab therapy in bail-out situations occurring during or early after PTCA. The use of abciximab in bail-out situations appears clinically beneficial. Further studies have to compare the efficacy of this approach with prophylactic abciximab treatment.

Toxicity, uptake kinetics and efficacy of new transfection reagents: increase of oligonucleotide uptake

Human arterial smooth muscle cell (haSMC) proliferation is stimulated by platelet-derived growth factor (PDGF) release of human arterial endothelial cells (haEC) whereas transforming growth factor-beta(1) (TGF-beta(1)) secretion by haSMC promotes extracellular matrix formation. Inhibitory concepts with antisense oligonucleotides (ASO) against those growth factors might be promising, requiring, however, sufficient transfection efficacy. Thus, toxicity and efficacy of new transfection reagents were examined. MTT tests showed that high doses >1.6 microg/ml of the liposome Cytofectin GSV((R)) (CF) and the dendrimer SuperFect (SF) reduced mitochondrial activity of haEC after > or =4 h transfection whereas viability of haSMC was not influenced. DAC-30((R)) showed significant toxic effects on haEC and haSMC at each dose after > or =4 h and Lipofectin((R)) (LF) caused complete detachment of haEC and haSMC in medium containing 10% serum. Uptake studies demonstrated that 'naked' ASO were not incorporated intracellularly whereas transfection within CF or SF resulted in a strong cytoplasmic and nuclear labeling after 2-5 h. With DAC-30, only a slight cytoplasmic fluorescence was found. SF caused an unexpected stimulation of endothelial PDGF-AB synthesis. Thus, CF was favored for inhibition studies. ELISA, Western and Northern blotting showed a significant inhibition of endothelial PDGF-B and smooth muscle TGF-beta(1) mRNA expression and synthesis after transfection for 3-5 h using 0.1-1.0 microM ASO versus control oligonucleotides. We conclude that Cytofectin GSV is superior to the other transfection reagents, predominantly at haEC, showing an improved efficacy and less toxicity than the classical liposome Lipofectin. Cytofectin GSV might offer a promising tool for antisense strategies in the treatment of vascular disorders.

Perspectives of coronary excimer laser angioplasty: multiplexing, saline flushing, and acoustic ablation control

BACKGROUND AND OBJECTIVE

Bubble formation, pressure wave generation, and cavitations constitute major factors influencing the outcome of clinical Excimer laser angioplasty. Thus, the rationale of this study was to determine the extent of pressure waves occurring during excimer laser ablation and to discuss possibilities that allow a less traumatic plaque removal in the coronary circulation.

STUDY DESIGN/MATERIALS AND METHODS

Conventional and experimental Xenon-Chlorid-Excimer lasers emitting light at a wave-length of 308 nm and a pulse duration of 115 ns were used for testing of signals. Whereas the conventional excimer laser light source transmits light through all fibers of a 1.7 mm laser catheter simultaneously, the prototype excimer laser divides the laser beam into several areas of uniform energy fluence by scanning the beam from one section to the other using the intermission between two laser discharges. Hydrophones consisting of piezoelectric films detected the acoustic signals, which were obtained on normal arterial wall and atherosclerotic plaque.

RESULTS

Multiplexing decreases maximum pressures for both normal arterial wall and calcified plaque significantly, whereas pressure rise time remains comparable. During ablation of pure blood, a linear increase of peak pressures of 1 MPa at 10 mJ/mm2 to 7.5 MPa at 50 mJ/mm2 is found. Contrast media intensifies the extent of pressure wave formation. At 20 mJ/mm2, 60% contrast media added to blood results in an increase of maximum pressures from 1.5 MPa up to 5 MPa. Dilution with saline solution is effective; however, high concentrations of > 90% are required to achieve a significant pressure wave reduction.

CONCLUSION

Peak pressures of several thousand kPa occur during excimer laser ablation of contrast media, blood, calcified plaque, and normal arterial wall in a decreasing order. Multiplexing and saline flushing are capable of reducing the intensity of the generated acoustic signals during tissue ablation. It has to be taken into consideration, however, that high concentrations of saline solution are necessary to achieve a significant reduction of peak pressures.

Local paclitaxel delivery for the prevention of restenosis: biological effects and efficacy in vivo

OBJECTIVE

The aim of this study was to evaluate the potential of paclitaxel to prevent restenosis in vivo.

BACKGROUND

Paclitaxel (Taxol) is a microtubule-stabilizing compound with potent antitumor activity. It influences the cytoskeleton equilibrium by increasing the assembly of altered microtubules, thereby inducing cellular modifications that result in reduced proliferation, migration and signal transduction.

METHODS

Before the in vivo study, delivery efficiency was determined with radiolabeled paclitaxel in porcine hearts. After induction of a defined plaque in the right carotid arteries of 76 New Zealand rabbits by electrical stimulation, 27 animals underwent balloon dilation and subsequent local paclitaxel delivery (10 ml, 10 micromol/liter) with a double-balloon catheter. Twenty-nine animals served as control with angioplasty only, 10 animals underwent local delivery of vehicle only (0.9% NaCl solution) and 10 animals were solely electrostimulated. Vessels were excised one, four, and eight weeks after intervention.

RESULTS

The extent of stenosis in paclitaxel-treated animals was significantly reduced compared with balloon-dilated control animals (p = 0.0012, one, four and eight weeks after intervention: 14.6%, 24.6% and 20.5%, vs. 24.9%, 33.8% and 43.1%, respectively). Marked vessel enlargement compared with balloon-dilated control animals could be observed (p = 0.0001, total vessel area after one, four and eight weeks: paclitaxel group: 1.983, 1.700 and 1.602 mm2, control: 1.071, 1.338 and 1.206 mm2, respectively). Tubulin staining and electron microscopy revealed changes in microtubule assembly, which were limited to the intimal area. Vasocontractile function after paclitaxel treatment showed major impairment.

CONCLUSIONS

Local delivery of paclitaxel resulted in reduced neointimal stenosis and enlargement in vessel size. Both these effects contribute to a preservation of vessel shape and are likely to be caused by a structural alteration of the cytoskeleton.

Local delivery of a low molecular weight heparin following stent implantation in the pig coronary artery

BACKGROUND

The low molecular weight heparin Reviparin reduces smooth muscle cell proliferation in cell culture experiments. Clinical studies with systemic application of the substance did not show a reduction of the incidence of restenosis following balloon angioplasty. Local delivery, by achieving higher local concentrations of the drug, may have the potential to decrease smooth muscle cell proliferation in the treated arterial segment.

OBJECTIVES

The aim of this study was to investigate the effects of local delivery of reviparin following stent implantation in the pig coronary artery.

METHODS

A coronary stent was implanted in the LAD of 34 pigs. In the treatment group 5 ml reviparin was injected with the Infusasleeve catheter at a proximal pressure of 80 psi. After 28 days the animals were sacrificed. Quantitative morphometric analysis comprised the intimal area, medial area and the lumen. The extent of vessel injury and the intimal thickness were assessed separately for each stent strut region. The correlation of injury and neointimal thickness was analysed using linear regression.

RESULTS

There was no relevant difference in the extent of vessel injury (1.9 +/- 0.7 vs. 1.6 +/- 0.6), the neointimal areas (2.4 +/- 0.9 vs. 2.4 +/- 1.0 mm2) and the resulting stenosis (46 +/- 18 vs. 47 +/- 17%). The medial area was larger in the animals treated with local delivery (2.2 +/- 0.4 vs. 1.6 +/- 0.4 mm2; p < 0.01). The correlation of injury and neointimal thickness was comparable in both groups. In two animals the passage of the stent area with the delivery system resulted in stent dislocation and fatal subacute thrombosis.

CONCLUSION

In this animal model, local delivery of reviparin with the Infusasleeve catheter did not result in a reduction of neointimal proliferation following stent implantation. Local delivery after stent implantation carries the risk of stent dislocation as a result of the passage with the delivery system.

[Paclitaxel: a chemotherapeutic agent for prevention of restenosis? Experimental studies in vitro and in vivo]

Paclitaxel, a potent anti-tumor agent, shifts the cytoskeleton equilibrium towards assembly of altered and extraordinarily stable microtubules. These cellular modifications lead to reduced proliferation, migration, and signal transduction. It is highly lipophilic, which promotes a rapid cellular uptake, and has a long-lasting effect in the cell due to the structural alteration of the cytoskeleton. This makes paclitaxel a promising candidate for local drug delivery intended to address the proliferative and migratory processes involved in restenosis. In this article, results of our in vitro and in vivo studies with paclitaxel are presented. Cell culture experiments with monocultures of human arterial smooth muscle cells as well as co-cultures with human endothelial cells showed that paclitaxel leads to an almost complete growth inhibition within a dose range of 1.0-10.0 mumol/l, even after a short (20 min) single dose application. The comparison of an active, semi-active, and passive delivery system (porous balloon, microporous balloon, and double balloon) favored the double balloon for the following in vivo experiments. Tubulin staining and electron microscopy enabled visualization of paclitaxel-induced vessel wall alterations. In the rabbit model, locally delivered paclitaxel resulted in reduced neointima formation and enlargement in vessel size; in the pig model, however, after stenting, this inhibition was not significant. Both reduced proliferation and enlargement in vessel size contribute to a preservation of vessel shape and are likely to be caused by a structural alteration of the cytoskeleton, which is also supported by vascular contraction force experiments.

Effects of cerivastatin on human arterial smooth muscle cell proliferation and migration in transfilter cocultures

Statins competitively inhibit 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase activity reducing mevalonate synthesis. In this study, antiproliferative and antimigratory effects of the new compound cerivastatin were analyzed and compared with classic statins of the first and second generation using mono- and cocultures of human arterial smooth muscle (haSMC) and endothelial (haEC) cells. Effects on the mitotic index and mitochondrial activity of haEC and haSMC monocultures were tested using BrdU enzyme-linked immunosorbent assay (ELISA) and 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) tests, respectively. In lactate dehydrogenase (LDH) assays, cytotoxicity of statins was studied. Transfilter cocultures were performed for 14 days to evaluate haSMC growth under the stimulatory effect of proliferating haEC, which release growth factors [e.g., platelet-derived growth factor (PDGF)]. The hydrophobic statins simvastatin, lovastatin, and atorvastatin significantly inhibited haSMC and haEC growth in monocultures at 0.5-50 microM. However, most potent effects were exerted by cerivastatin in 10- to 30-fold lower doses without any significant cytotoxicity. More important, cerivastatin showed also significant effects on haSMC proliferation and migration in transfilter cocultures at extremely low doses (IC50, 0.04-0.06 microM), even when applied exclusively to the endothelial side and in the presence of low-density lipoprotein (LDL). Addition of mevalonate abolished the effects of cerivastatin completely. Even in the presence of growth-stimulating haEC and LDL, cerivastatin was found to be the most potent inhibitor of haSMC proliferation and migration in doses that also can be reached in human serum after oral drug administration. The results support the concept that statins seems to influence additional cellular mechanisms beyond cholesterol reduction, which might also have a relevance for the prevention of restenosis.

[Results of a survey of 549 patients regarding long-term clinical outcome and quality of life four years after PTCA]

BACKGROUND

Quality control becomes increasingly important in interventional cardiology. Since in most health care systems, clinical treatment of patients who underwent percutaneous transluminal coronary angioplasty (PTCA) is left to general practitioners, important information on the clinical long-term outcome is lost for the cardiologic centers. Aim of this study was to evaluate the clinical status of these patients 4 years after treatment with a PTCA at our institution.

PATIENTS AND METHODS

Inclusion criterion was the treatment with a PTCA within July 1, 1989 to June 30, 1991 (549 patients). A questionnaire was sent to all patients (45 +/- 7 months after PTCA). Four time-points were defined: before PTCA (T1), directly after PTCA (T2), 3 months after PTCA (T3) and actual status (T4).

RESULTS

Questionnaires of 500/549 (91.1%) patients could be analyzed. One-hundred and fifteen patients (23%) had to undergo reinterventions: 69 (13.8%) had a re-PTCA and 46 (9.2%) patients an operative revascularization. At T4, 11.2% patients still had disturbing angina. Within the study period 35 patients (7%) died. Two-hundred and nineteen patients attended a rehabilitation institution. At T4, the amount of patients with little angina was not different comparing patients with/without the attendance of a rehabilitation institution (60.7% vs 66.4% p = 0.29). The rate of new pensioners after PTCA (n = 114 [22.8%]) was higher in the group of patients who attended a rehabilitation (68 patients [13.6%] with vs 48 patients [9.2%] without attendance, p = 0.0036). The attendance of a rehabilitation institution, however, had positive effects on changes of the life style and eating habits.

CONCLUSIONS

This retrospective inquiry was found to be a useful tool (response rate 91.1%) for quality control in interventional cardiology. Important information concerning the quality of the interventions (low reintervention rate) and the long-term outcome of our patients (low rate with severe angina at T4) could be acquired.

The impact of untreated coronary dissections on acute and long-term outcome after intravascular ultrasound guided PTCA

AIM

Vessel size adapted PTCA results in the use of larger balloons with an increased incidence of severe vascular dissections. The aim of our trial was (a) to evaluate the effect of severe dissections on the acute outcome and (b) to study the natural history of dissections after 1 year.

METHODS AND RESULTS

One hundred and seventy-eight patients with 195 lesions underwent vessel size adapted PTCA using intravascular ultrasound. Clinical and angiographic 1 year follow-up was obtained for all patients. Intravascular ultrasound was performed before PTCA to measure the external elastic membrane diameter at the lesion site so that the balloon size could be adopted (external elastic membrane-10%) and post-interventionally to determine the procedural success and the incidence of intracoronary dissections. Stent implantation was reduced to persistently flow limiting dissections (TIMI I, II). Dissections were detected by intravascular ultrasound in 128/195 (66%) lesions (by angiography in 111/195 [58%] lesions) and classified by intravascular ultrasound criteria into four groups: group I: no dissection (67 lesions [34%]), group II: mild dissections (21 lesions [11%]), group III: medium dissections (19 lesions [10%]) and group IV: severe dissections (88 lesions [45%]). Because of threatened vessel closure, GPIIb/IIIa antagonists were used in eight (4.5%) patients and a stent was implanted in two (1. 1%) patients. The cumulative event rate after 1 year was 12% and the global angiographic restenosis rate was 19%. The post-interventional evidence of severe dissections was associated with a decrease in clinical events during long-term follow up (group I: 13 events [19%] vs group IV: seven events [7%];P=0.03). This was also true for the occurrence of restenosis which was significantly lower in patients with severe dissections (group I: 19 [28%] lesions vs group IV:10 [11%] lesions;P=0.01).

CONCLUSIONS

According to the theory of 'therapeutic dissections', our data suggest that substantial dissections following PTCA, which do not diminish antegrade blood flow, do not lead to an increase in acute or long-term events. The natural history of vessel injury seems to provide favourable wound healing without increase of restenosis. Thus, stenting for treatment of large dissections without flow limitation does not seem to be mandatory.

Visualization and comparison of drug effects after local paclitaxel delivery with different catheter types

BACKGROUND

The microtubule stabilizing compound paclitaxel has proved to have potent antiproliferative effects on smooth muscle cells both in vitro and in vivo. It induces cellular modifications that result in reduced proliferation, migration and signal transduction by shifting the cellular microtubule equilibrium towards assembly. We therefore reasoned that a visualization of the altered cytoskeleton could enable an evaluation of the drug effects following local drug delivery.

METHODS AND RESULTS

3 catheters - the porous balloon, the microporous balloon and the double balloon catheter - were chosen for this study representing the spectrum from passive to active, pressure-driven delivery. After the induction of a defined plaque in the right carotid arteries of 40 New Zealand rabbits by electrical stimulation, 32 animals underwent balloon dilatation and 8 animals served as pre-interventional control group with electrostimulation only. In 24 animals (n = 8 in each group) subsequent local paclitaxel delivery (10 micromol/L) was performed. 8 animals served as control with angioplasty only. Vessels were excised 1 week following intervention. Immunohistochemistry with antibodies against bromodeoxyuridine, alpha-actin, macrophages, von Willebrand factor and alpha-tubulin was performed. Cytoskeletal changes were analyzed by electron microscopy. Tubulin staining and electron microscopy revealed changes with distinct staining patterns for the different catheters. Specific catheter-induced injuries could be identified for the porous and double balloon catheter. Intimal proliferation, percentage of macrophages and extent of injury favor the double balloon catheter for local paclitaxel delivery.

CONCLUSIONS

The alterations of the cytoskeleton induced by paclitaxel allowed for the detection of drug action by staining of tubulin and electron microscopy. This enables an evaluation of transfer, distribution and drug effects directly in the vasculature without marker substances. The double balloon catheter appears to be best suited for local paclitaxel therapy.

Noninvasive determination of endothelium-mediated vasodilation as a screening test for coronary artery disease: pilot study to assess the predictive value in comparison with angina pectoris, exercise electrocardiography, and myocardial perfusion imaging

BACKGROUND

Peripheral endothelial dysfunction (ED) quantified by the determination of flow-mediated dilation (FMD%) of the brachial artery with the use of high-resolution ultrasound is an early marker of atherosclerosis. Although a positive correlation with coronary artery disease (CAD) has been reported, the unanswered clinical question is the validity of FMD% as a screening test in patients with clinical suspicion of CAD. Thus the aim of this study was to determine the predictive value of FMD% compared with angina pectoris, exercise electrocardiography, and myocardial perfusion imaging.

METHODS AND RESULTS

In this pilot study, we measured ED in 122 patients scheduled for coronary angiography by using high-resolution ultrasound (13 MHz). We defined ED as FMD% </=4.5%. The presence of CAD was defined as angiographically detectable atherosclerotic vessel alterations of any degree. Exercise electrocardiography and myocardial perfusion imaging had been performed on an outpatient basis. Statistical analysis was conducted by analysis of variance and Mantel-Haenszel chi-square test. Patients with CAD (n = 101) had a significantly lower FMD% than patients without CAD (n = 21; 3.7% +/- 4.1% vs 7.01% +/- 3.5%, P <.001). A sensitivity of 71%, a specificity of 81% with a positive predictive value of 0.95 (72 of 76), and a negative predictive value of 0.41 (17 of 46) was calculated. In comparison to angina pectoris (sensitivity 95%, specificity 47.6%), exercise electrocardiography (sensitivity 82.4%, specificity 57.1%) and myocardial perfusion imaging (sensitivity in our study group 100%) had the best specificity, and a high sensitivity for FMD% was found.

CONCLUSIONS

The determination of ED was found to be a sensitive and specific screening test to predict the presence of CAD. Because this is a noninvasive, nonradioactive, and cost-effective approach, it warrants further evaluation to determine its value in daily clinical practice as an additional screening test in the diagnosis of CAD.

Effect of HMG-CoA reductase inhibitors on extracellular matrix expression in human vascular smooth muscle cells

Clinical studies have shown that treatment with 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitors can stabilize atherosclerotic plaques and slow their progression. One determinant of plaque stability and size is the composition of the vascular extracellular matrix. The aim of this study was to evaluate the effects of different HMG-CoA reductase inhibitors on the expression of major components of the vascular extracellular matrix in smooth muscle cells. Cultured human vascular smooth muscle cells were incubated for 24-72 h with the HMG-CoA reductase inhibitors lovastatin (1-50 micromol/L), simvastatin (0.05-20 micromol/L), and pravastatin (1-100 micromol/L). RNA expression of the extracellular matrix proteins thrombospondin-1, fibronectin, collagen type I, and biglycan as well as expression of the cytokine TGF-beta1 was determined by Northern blotting. Extracellular matrix protein secretion was visualized by immunofluorescence. In addition, cell proliferation and viability were measured using BrDU-ELISAs, MTT-tests, and direct cell counting. Expression of thrombospondin-1 was significantly decreased after 24 h incubations with lovastatin in concentrations as low as 1 micromol/L. Coincubation with the cholesterol precursor mevalonate completely reversed this effect. The downregulation of thrombospondin-1 expression occured in the same concentration range that also inhibited cell proliferation. In contrast, lovastatin did not affect expression of fibronectin, whereas collagen type I and biglycan expression decreased only after long incubations with high, toxic lovastatin concentrations. Simvastatin, but not the very hydrophilic compound pravastatin, had a similar effect on extracellular matrix expression as lovastatin. In summary, lovastatin and simvastatin predominantly decrease the expression of the glycoprotein thrombospondin-1, which is functionally associated with smooth muscle cell migration and proliferation. In contrast, expression of plaque-stabilizing extracellular proteins such as collagen type I and biglycan are much less affected.

Angiotensin I-converting enzyme gene polymorphism, coronary artery disease and myocardial infarction. An angiographically controlled study

OBJECTIVES

We investigated the association between insertion/deletion polymorphism of the angiotensin I-converting enzyme (ACE) gene, the presence and extent of coronary artery disease, and myocardial infarction.

BACKGROUND

The D allele of the ACE gene has been associated with coronary artery disease and myocardial infarction, but this association has been challenged in epidemiological studies.

METHODS

Nine hundred and sixty-nine men and 341 women undergoing coronary angiography were studied. The ACE genotypes were assessed by polymerase chain reaction from genomic deoxyribonucleic acid, homozygosity for the D allele was controlled using an insertion-specific primer. Coronary artery disease was defined by angiographic criteria, the extent of coronary artery disease by the number of coronary arteries with >/=50% lumen narrowing.

RESULTS

The ACE genotypes did not differ in terms of age, sex, body mass index, blood pressure, plasma lipids or lipoproteins. We found no association between the ACE genotypes and coronary artery disease (odds ratio, 95% confidence interval in DD genotypes for coronary artery disease in men 0.97, 0.70-1.36; in women 1.56, 0.95-2.57), extent of coronary artery disease (men 1.17, 0.85-1.61; women 1.24, 0.65-2.34), or myocardial infarction among the patients with coronary artery disease (men 1.07, 0.78-1.48; women 0.95, 0.50-1.76). The ACE genotype was not associated with coronary artery disease or myocardial infarction in hypertensives (n=771; odds ratio for coronary artery disease 0.93, 0.65-1.34; odds ratio for myocardial infarction 0.94, 0.66-1.33), or in patients </=60 years (n=649; odds ratio for coronary artery disease 1.05, 0.72-1.52; odds ratio for myocardial infarction 0.96, 0.63-1.47).

CONCLUSION

ACE insertion/deletion gene polymorphism is associated neither with the prevalence nor the extent of coronary artery disease, nor with myocardial infarction in this relatively large sample of Caucasian men and women. Genotyping for ACE insertion/deletion polymorphism is not useful in assessing the individual risk of coronary artery disease or myocardial infarction.