Local photodynamic therapy reduces tissue hyperplasia after stenting in an experimental restenosis model.

Local photodynamic therapy was used to prevent neointimal hyperplasia after stenting. Slotted tube stents were placed with 16 atmospheres in porcine femoral arteries with the external diameter to match the diameter at 10 atmospheres. Animals were randomly allocated to Group 1 (stenting only); or Group 2 with stenting, local drug delivery of a photosensitizer (5 mg Photofrin) and subsequent exposure to light (photodynamic therapy, 100 J).

High-resolution MR angiography: results in diseased arteries.

The purpose of this study was to investigate the value of a respiratory-gated three-dimensional (3D) magnetic resonance angiographic technique (MRCA) in identifying coronary arteries in healthy volunteers and patients with proximal coronary artery stenoses and to compare the results of the navigator echo technique in the assessment of coronary artery stenosis with conventional coronary angiography. Twenty healthy volunteers and twenty patients with proximal coronary artery stenosis were examined at 1.5 Teslas with a cardiac-gated and retrospective respiratory-gated 3D gradient echo sequence.

Local Drug Delivery for Restenosis and Thrombosis Ñ Progress?

Platelet activation, inflammation, recoil, tissue hyperplasia and remodeling are pivotal pathophysiologic factors in acute myocardial ischemia and restenosis development after angioplasty. Even after the rising use of stents, the tremendous amount of resulting tissue hyperplasia remains a therapeutic problem. It has been suggested that short duration of effective drug levels and poor efficiency of systemic drug administration account for the failure of therapy in clinical trials.

Local drug delivery via transvascular injection.

Background: In this experimental series we tested drug distribution and systemic leakage using local drug delivery with a new transvascular injection system.

Methods: Porcine femoral and carotid arteries (n = 56) underwent local drug application with a new 5 French (Fr) over-the-wire needle-injection catheter system (NIC) using three needles. A radioactive indicator [C14-Carvedilol, 2.

Navigator echo-based respiratory gating for three-dimensional MR coronary angiography: results from healthy volunteers and patients with proximal coronary artery stenoses.

Objective: The purpose of our study was to investigate the value of respiratory-gated three-dimensional (3D) MR angiography in identifying coronary arteries in healthy volunteers and in patients with proximal coronary artery stenosis and to compare the results with those of conventional coronary angiography.

Subjects And Methods: Twenty healthy volunteers and 20 patients with coronary artery stenosis were examined on a 1.5-T scanner with a retrospectively respiratory-gated 3D gradient-echo sequence.

Endovascular catheter-delivered photodynamic therapy in an experimental response to injury model.

Background: The effectiveness of local endovascular photodynamic therapy (PDT) in preventing tissue hyperplasia was evaluated in a vascular injury model.

Methods: Standardized unidirectional arterial injury with a directional atherectomy catheter was performed in porcine arteries (n = 180). Animals (n = 72) were randomly allocated to unidirectional injury only (Group 1), injury followed by drug delivery of photosensitizer with a porous balloon (Group 2), or by local exposure to monochromatic light (Group 3).

Local photodynamic therapy reduces tissue hyperplasia in an experimental restenosis model.

Local photodynamic therapy may have potential in preventing myointimal hyperplasia after angioplasty. In this study, the effect of photodynamic therapy was evaluated in an experimental model of restenosis. Standardized unidirectional arterial injury with a directional atherectomy catheter was performed in porcine arteries.

[Local drug administration systems, preclinical and clinical use: perspectives and limitations].

Platelet activation, inflammation, recoil, tissue hyperplasia and remodeling are pivotal pathophysiologic factors in acute myocardial ischemia and restenosis development after angioplasty. It has been suggested that short duration of effective drug levels and poor efficiency of systemic drug administration account for the failure of therapy in clinical trials. A rational effective therapy for angina and restenosis should therefore be locally administered at the site of vascular obliteration.

Comparison of local intravascular drug-delivery catheter systems.

Systemic and local delivery of the photosensitive drug Photofrin polyporphyrin was investigated in normal porcine arteries (n = 192). A macroporous balloon and a novel needle injection catheter were used for local drug delivery and compared with systemic delivery. Fluorescence microscopy combined with digital image analysis was used to quantify the drug-related fluorescence.

[Coronary sinus blood flow after intracoronary or intravenous administration of bisoprolol in coronary disease].

Objective: To measure changes in haemodynamics and myocardial blood flow after acute intravenous (i.v.) and intracoronary (i.

Experimental directional atherectomy injury in arterial vessels: impact of trauma depth on cellular response.

This study investigates cellular alterations after directional atherectomy vessel injury (DI) in an experimental model in 50 pigs. Two hundred arteries were excised at eight different times (2 hours to 21 days) after DI and were examined by electron microscopy and immunohistochemistry. The extent of injury varied with the number of repetitive passes of the atherectomy catheter.

A new catheter for prolonged local drug application.

Background: Local drug delivery using a new 5F catheter with six small needles is described. The needles can be extended laterally into vascular tissue for drug deposition.

Methods: A fluorescent indicator (Photofrin) was injected with a new local drug delivery device into porcine carotid arteries.

Ultrastructural characteristics of cellular reaction after experimentally induced lesions in the arterial vessel.

Unlabelled: Restenosis after angioplasty occurs with an incidence of 20-50% and remains a major drawback. Certain randomized studies suggest that a bigger post-angioplasty lumen predicts a better long-term outcome. Conversely other studies showed a better outcome with limited injury.

[Drug and instrumental therapeutic approaches for prevention of restenosis].

In recent years, several of the shortcomings of coronary angioplasty have been successfully countered. With more effective measures of treating acute complications, better equipment and more experienced operators, there has been a subsequent expansion of the indications and the type of lesions suitable for angioplasty. In the long-term, however, the restenosis rate remains the limiting factor for the success of the procedure.

[Ultrastructural characteristics of cellular reaction to experimental catheter-induced lesions of arterial blood vessels].

Unlabelled: After angioplasty, restenosis remains the major drawback of the procedure with an incidence of between 20-40%. It is a matter of concern whether the cellular alterations start immediately after directional atherectomy (DA) and if they are dependent on the depth of the lesion.

Method: Cellular alterations immediately after DA were investigated using peripheral atherectomy in normal vessels of 30 pigs (A.

[Pathophysiology and pathobiochemistry of restenosis].

The high rate of restenosis after percutaneous transluminal angioplasty obviously depends on multiple factors. Predictors for the clinical outcome seem to be the selection of lesion morphology, the acute result and the biological vessel response in the first months after treatment. Thrombus formation and recoil have been considered to be pivotal events.

[Immunohistologic cell characterization of tissue of primary and re-stenoses].

Smooth muscle cells and macrophages are essential parts of arteriosclerotic lesions. This study should enable the analysis of different functional and morphological features of cells in primary and restenotic biopsies. Therefore detection of specific cell markers in human arteriosclerotic material derived from directional coronary atherectomy (DCA) of primary and restenotic lesions was used.

Analysis of atherectomy specimens.

Atherectomy specimens may be regarded as biopsy tissue excised from human vascular target lesions. Proceeding from contrary histologic findings that attribute focal hypercellularity to restenosis, and hypocellularity to chronic lesions, further analysis of atherectomy specimens was performed to study ultrastructural characteristics and functional aspects propagated by both lesion types. Transmission electron microscopy examination showed that intimal smooth muscle cells (SMCs) were the predominant cells in both primary and restenotic lesions.