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Biomedical subjects

Timm Dickfeld

Publications and source records attributed to Timm Dickfeld.

23 records · Page 2Linked to original sources
PubMed2003

Activated platelets trigger an inflammatory response and enhance migration of aortic smooth muscle cells.

OBJECTIVE: Exposure of the subendothelium to flowing blood following rupture of atherosclerotic lesions or during balloon angioplasty initiates platelet adhesion to the vascular wall. Because activated platelets release proinflammatory mediators (e.g., interleukin (IL)-1beta) and secrete growth factors, platelet adhesion to the subendothelial matrix might contribute to the recruitment of inflammatory cells and promote migration and proliferation of vascular smooth muscle cells (SMCs). METHODS AND RESULTS: Here, we demonstrate that incubation of cultured monolayers of aortic SMCs with alpha-thrombin-activated platelets significantly enhances the secretion of monocyte chemoattractant protein-1 (MCP-1) (P<0.05) and promotes SMC migration (P<0.05). Platelet-induced secretion of MCP-1 was abolished by anti-IL-1alpha and beta monoclonal antibodies or the IL-1 receptor antagonist (IL-1RA). In contrast, platelet-mediated SMC migration was attenuated only by anti-platelet-derived growth factor (PDGF)-mAb but not by IL-1RA. Correspondingly, recombinant human interleukin-1 (rhIL-1) beta increased MCP release by SMCs but had no effect on SMC migration. Platelet-mediated MCP secretion by SMCs involved the activation and nuclear translocation of the transcription factor nuclear factor-kappaB (NF-kappaB). CONCLUSION: Therefore, platelet adhesion to the subendothelium increases the chemotactic and migratory properties of SMC and is likely to contribute substantially to the process of atherosclerosis and vessel (re-)stenosis.

Aorta↗
PubMed2003

Pulmonary vein anatomy in patients undergoing catheter ablation of atrial fibrillation: lessons learned by use of magnetic resonance imaging.

BACKGROUND: This study sought to define the technique and results of magnetic resonance imaging (MRI) of pulmonary vein (PV) anatomy before and after catheter ablation of atrial fibrillation (AF). METHODS AND RESULTS: Twenty-eight patients with AF underwent ablation. Patients underwent gadolinium-enhanced MRI before and 6 weeks after their procedures. A control group of 27 patients also underwent MRI. Variant PV anatomy was observed in 38% of patients. AF patients had larger PV diameters than control subjects, but no difference was observed in the size of the PV ostia among AF patients. The PV ostia were oblong in shape with an anteroposterior dimension less than the superoinferior dimension. The left PVs had a longer "neck" than the right PVs. A detectable PV narrowing was observed in 24% of veins. The severity of stenosis was severe in 1 vein (1.4%), moderate in 1 vein (1.4%), and mild in 15 veins (21.1%). All patients were asymptomatic, and none required treatment. CONCLUSIONS: This study demonstrates that AF patient have larger PVs than control subjects and demonstrates the value of MRI in facilitating AF ablation. The benefits of preprocedural MRI of PVs include the ability to evaluate the number, size, and shape of the PVs. MRI also provides an assessment of the severity of PV stenosis.

Atrial Fibrillation↗
PubMed2003

Real-time cardiac catheter navigation on three-dimensional CT images.

INTRODUCTION: Targets for ablation of atrial fibrillation, atrial flutter, and non-idiopathic ventricular tachycardia are increasingly being selected based on anatomic considerations. Because fluoroscopy provides only limited information about the relationship between catheter positions and cardiac structures, and is associated with radiation risk, other approaches to mapping may be beneficial. METHODS: The spatial and temporal information of an electromagnetic catheter tip position sensing system (Magellan, Biosense Inc.) was superimposed on a three-dimensional (3D) CT of the chest in swine using fiducial markers for image registration. Position and orientation of a 6 French catheter with an electromagnetic sensor was displayed in real-time on a corresponding 3D-CT. Catheter navigation within the heart and the great vessels was guided by detailed knowledge about catheter location in relation to cardiac anatomy. RESULTS: Anatomic structures including the atrial septum, pulmonary veins, and valvular apparatus were easily identified and used to direct catheter navigation. During the right heart examination, the catheter was navigated through the superior and inferior vena cava to predetermined anatomic locations in right atrium, right ventricle and pulmonary artery. The ablation catheter was also navigated successfully from the aorta through the aortic valve in the left ventricle. No complication was encountered during the experiments. The accuracy and precision of this novel approach to mapping was 4.69 +/- 1.70 mm and 2.22 +/- 0.69 mm, respectively. CONCLUSIONS: Real-time display of catheter position and orientation on 3D-CT scans allows accurate and precise catheter navigation in the heart. The detailed anatomic information may improve anatomically based procedures like pulmonary vein ablation and has the potential to decrease radiation times.

Animals↗
PubMed2002

Percutaneous coronary intervention vs. medical therapy: what are the implications for women?

There have been eight major studies assessing percutaneous coronary intervention (PCI) vs. medical therapy in the past 10 years. Women were inadequately represented in many of these studies, but because of similar long-term survival curves in women and men, most of the PCI data can be applied to women until more trials are published. According to currently available data, PCI offers greater angina relief and improvement in exercise tolerance than medicine alone, but has a greater risk of procedure-related complications in women. As a result of the rapid advancement of cardiovascular therapy, many of these studies did not incorporate optimal medical therapy or current PCI therapies. It is likely that for most patients (including women) with moderate angina, the best management may be a combination of PCI, medical therapy, and lifestyle changes.

Angioplasty, Balloon, Coronary↗