Biomedical subjects

Dieter Raithel

Publications and source records attributed to Dieter Raithel.

8 recordsLinked to original sources

PubMed2007

Accumulation of immune cells and high expression of chemokines/chemokine receptors in the upstream shoulder of atherosclerotic carotid plaques.

The presence of immune cells is important for plaque destabilization. Disturbed flow conditions were shown to enhance the recruitment of circulating immune cells. Thus, we analyzed in 54 atherosclerotic carotid plaques the frequency of different immune cells, HLA-DR, chemokines, and chemokine receptors, comparing the upstream with the downstream plaque shoulder. The presence of neovascularization and intraplaque hemorrhages was investigated by CD34 immunostaining and Mallory's iron stain. Immunohistochemical analyses were performed to detect smooth muscle cells (SMC: actin), macrophages (CD68), T cells (CD3), dendritic cells (DC: fascin), mature DC (CD83), and the expression of HLA-DR, chemokine receptors (CCR-2, CCR-6), and chemokines (MCP-1, MIP-3alpha). Significantly more SMC were detected downstream than upstream (p<0.001). In contrast, significantly more macrophages (p=0.01), DC (p=0.03), mature DC (p=0.007), and a higher expression of HLA-DR (p=0.004), CCR-2 (p=0.002), CCR-6 (p<0.001), MCP-1 (p=0.04), and MIP-3alpha (p=NS) were observed upstream than downstream. Immune cells were strongly associated with neovascularization. The abundance of SMC downstream provides an explanation for distal plaque growth. Enhanced recruitment of immune cells through neovessels into the upstream shoulder might be contributing to plaque destabilization.

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PubMed2006

Decrease in circulating myeloid dendritic cell precursors in coronary artery disease.

OBJECTIVES: We analyzed the frequency of myeloid dendritic cell (mDC) and plasmacytoid dendritic cell (pDC) precursors in blood of patients with coronary artery disease (CAD) and in atherosclerotic carotid plaques of patients with cerebrovascular disease (CVD). BACKGROUND: Circulating DC precursors are reduced in several autoimmune diseases. Atherosclerosis has features of an autoimmune disease, such as the presence of autoantibodies or autoreactive T cells. Tissue-resident DCs were previously described in atheromata, and it is assumed that they are important for the activation of T cells against autoantigens there. METHODS: Circulating mDC and pDC precursors were flow cytometrically detected in healthy controls (n = 19), CAD patients with stable (n = 20) and unstable angina pectoris (n = 19), and acute myocardial infarction (n = 17). In human carotid plaques (n = 65), mDC and pDC precursors were identified immunohistochemically. RESULTS: Circulating mDC precursors were significantly reduced in patients with stable angina pectoris (0.19%, p = 0.04), unstable angina pectoris (0.16%, p = 0.004), and acute myocardial infarction (0.08%, p < 0.001) compared with control patients (0.22% of peripheral blood mononuclear cells). In contrast, pDC numbers were not significantly altered. Circulating mDC precursors inversely correlated with high-sensitivity C-reactive protein (r = -0.38, p = 0.001) or interleukin-6 (r = -0.42, p < 0.001). In contrast to pDC, significantly more mDC precursors were observed in vulnerable carotid plaques (24, 0.25 mm2; n = 31; p = 0.003) than in stable ones (6.4, 0.25 mm2; n = 34). CONCLUSIONS: Similar to autoimmune diseases, circulating mDC precursors were significantly reduced in patients with CAD. The emergence of mDC precursors in vulnerable plaques suggests their recruitment into atheromata as a possible reason for their decrease in blood. In contrast, no significant association of circulating pDC precursors with atherosclerosis was observed.

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PubMed2006

Aortocaval fistula after stent-graft repair.

PURPOSE: To report an aortocaval fistula after stent-graft repair and the feasibility of interventional treatment. CASE REPORT: A 78-year-old man with a 61-mm infrarenal aortic aneurysm (AA) was treated successfully with a Zenith bifurcated stent-graft. Three years later, the patient presented with deteriorating renal function and acute bronchial obstruction. Computed tomography showed an aortic diameter increased to 90 mm, dilatation of the inferior vena cava, and a distal type I endoleak. The patient's condition quickly deteriorated, and emergent imaging found a fistula with brisk flow between the aneurysm sac and the left iliac vein within a distal type I endoleak. During emergency endovascular repair, iliac extensions were implanted in the right common iliac artery and left external iliac artery. The left hypogastric artery was coil embolized to exclude flow into the aneurysm sac. After positioning the extensions, cardiac function improved, and the fistula was no longer palpable. The cardiac indices and renal function normalized, and he was discharged 20 days after admission. CONCLUSION: Aortocaval fistulas are a rare complication of AA stent-graft repair and may be successfully treated by interventional means.

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PubMed2005

Connective tissue growth factor is overexpressed in complicated atherosclerotic plaques and induces mononuclear cell chemotaxis in vitro.

OBJECTIVE: Atherosclerotic blood vessels overexpress connective tissue growth factor (CTGF) mRNA, but the role of CTGF in atherosclerosis remains controversial. To assess the hypothesis that CTGF is involved in atherosclerotic plaque progression, we investigated CTGF protein expression and distribution in the different types of plaque morphology. METHODS AND RESULTS: Serial cross-sections of 45 human carotid plaques were immunohistochemically analyzed for the presence of CTGF protein, neovascularization (von Willebrand factor), macrophages (CD68), and T cells (CD3). The lesions were categorized according to American Heart Association (AHA) classification as fibrous (type IV and V) or complicated plaques (type VI). The levels of CTGF were significantly higher in complicated compared with fibrous plaques (P=0.002). CTGF accumulated particularly in the rupture-prone plaque shoulder and in the areas of neovascularization or infiltration with inflammatory cells. Macrophage-like cells stained positive for CTGF protein in plaques. Subsequent in vitro studies showed that although monocyte-derived macrophages do not produce CTGF on stimulation with transforming growth factor-beta, lipopolysaccharide, or thrombin, they take it up from culture medium. Furthermore, CTGF induces mononuclear cell chemotaxis in a dose-dependent manner. CONCLUSIONS: CTGF protein is significantly increased in complicated compared with fibrous plaques and may enhance monocyte migration into atherosclerotic lesions, thus contributing to atherogenesis.

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PubMed2004

Carotid plaque echolucency increases the risk of stroke in carotid stenting: the Imaging in Carotid Angioplasty and Risk of Stroke (ICAROS) study.

BACKGROUND: Carotid artery stenting (CAS) has recently emerged as a potential alternative to carotid endarterectomy. Cerebral embolization is the most devastating complication of CAS, and the echogenicity of carotid plaque has been indicated as one of the risk factors involved. This is the first study to analyze the role of a computer-assisted highly reproducible index of echogenicity, namely the gray-scale median (GSM), on the risk of stroke during CAS. METHODS AND RESULTS: The Imaging in Carotid Angioplasty and Risk of Stroke (ICAROS) registry included 418 cases of CAS collected from 11 international centers. An echographic evaluation of carotid plaque with GSM measurement was made preprocedurally. The onset of neurological deficits during the procedure and the postprocedural period was recorded. The overall rate of neurological complications was 3.6%: minor strokes, 2.2%, and major stroke, 1.4%. There were 11 of 155 strokes (7.1%) in patients with GSM < or =25 and 4 of 263 (1.5%) in patients with GSM >25 (P=0.005). Patients with severe stenosis (> or =85%) had a higher rate of stroke (P=0.03). The effectiveness of brain protection devices was confirmed in those with GSM >25 (P=0.01) but not in those with GSM < or =25. Multivariate analysis revealed that GSM (OR, 7.11; P=0.002) and rate of stenosis (OR, 5.76; P=0.010) are independent predictors of stroke. CONCLUSIONS: Carotid plaque echolucency, as measured by GSM < or =25, increases the risk of stroke in CAS. The inclusion of echolucency measured as GSM in the planning of any endovascular procedure of carotid lesions allows stratification of patients at different risks of complications in CAS.

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PubMed2003

Incidence of renal infarctions after endovascular AAA repair: relationship to infrarenal versus suprarenal fixation.

PURPOSE: To analyze the incidence and etiology of renal infarctions following endovascular abdominal aortic aneurysm (AAA) repair detected on computed tomography (CT) and determine any association with infrarenal versus suprarenal fixation. METHODS: Between August 1994 and October 2001, 663 patients (604 men; mean age 68.5 years, range 40-98) underwent endovascular AAA repair with predominately bifurcated (505, 77%) stent-grafts. About a third (202, 30%) of the devices were deployed in a suprarenal position. Contrast-enhanced CT scans were performed on days 10, 90, and 365 after operation and then annually. Two radiologists blinded to procedural details compared the preoperative and postoperative scans to identify renal infarctions from inadvertent renal artery occlusion by the endograft. Only patients with inadvertent infarctions were analyzed relative to endograft fixation position and stent-graft type. RESULTS: Mean follow-up was 37 months (range 0.1-75). Overall renal infarction rate was 11.9% (n=79); 23 (3.4%) patients suffered from limited, segmental infarction due to intentional covering of preoperatively diagnosed accessory renal arteries. Unintentional renal ischemia was identified in 56 (8.5%) patients. In this subgroup, 39 (19%) were observed in the 202 patients with suprarenal fixation versus 17 (3.7%) in the 461 stent-grafts positioned infrarenally (RR 3.35, 95% CI 2.20 to 5.04, p<0.00001). There was a significant correlation between the incidence of infarction and the device type (14.3% for modular grafts versus 5.6% for unibody designs, p=0.0002). Seventeen (2.6%) patients suffered from unilateral kidney loss, with dialysis required in 2 cases. Creatinine and urea showed no significant postoperative elevation in the overall patient population, but both levels were significantly (p<0.02) elevated in patients with complete unilateral renal infarcts. CONCLUSIONS: Transrenal fixation of aortic endografts had a 3-fold higher risk for renal infarction in this large patient population. There is no significant difference for specific endografts, but modular designs were associated with a higher rate of renal infarction. The need to occlude preoperatively diagnosed accessory renal arteries with an endograft should be considered a contraindication for current available devices.

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PubMed2002

Ruptured abdominal aortic aneurysm after endovascular repair.

OBJECTIVE: The purpose of this study was to present the experience with aneurysm rupture after deployment of Guidant/EVT (Guidant) endografts and review previously reported cases with other devices. METHODS: Records from Guidant/EVT clinical trials and postmarket approval databases from February 1993 to August 2000 were analyzed to identify patients with rupture and to extract pertinent data. Previously reported cases were obtained with a Medline search. RESULTS: Seven ruptures were found with Guidant/EVT devices. Five of these occurred among the 686 patients in US Food and Drug Administration protocols (group I) who were followed for a mean of 41.8 +/- 21.9 months and limited to the subgroup of 93 first generation tube endografts. Two ruptures occurred in group II (3260 patients after market approval with limited follow-up), specifically in the subgroup of 166 patients who underwent treatment with second generation tube grafts. No ruptures were found in patients with bifurcation or unilateral iliac implants followed for a mean of 37.5 months. All ruptures were caused by distal aortic type I endoleaks on the basis of attachment system fractures (first generation devices only), aortic neck dilatations, persistent primary endoleaks, migration, overlooked imaging abnormalities, refused reintervention, and poor patient selection. The mortality rate was 57% (4/7) overall and was 50% for surgical repair (3/6). A literature search identified 40 additional ruptures related to other devices, for a total of 47. All 44 that were documented with adequate data were caused by endoleaks (26 type I, 2 type II, 11 type III, and 5 source not reported). Other contributing factors were graft module separation and graft wall deterioration. The overall mortality rate for the combined series was 50%, with an operative mortality rate of 41%. CONCLUSION: Postendograft AAA rupture is infrequent, although the true incidence rate is unclear because of inadequate follow-up of individual device designs. Tube endografts should be limited to the rare patient with ideal anatomy, no other alternatives, and at high risk for standard open repair. Prevention of aneurysm rupture requires long-term surveillance with attention to subtle imaging abnormalities and the establishment of reliable follow-up protocols for specific devices. The outcome of postendograft aneurysm rupture is similar to that of rupture without prior endograft therapy.

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PubMed2002

Surgical conversion after endovascular grafting for abdominal aortic aneurysms.

PURPOSE: To analyze the indications, results, and technical problems associated with conversion after endoluminal repair of abdominal aortic aneurysms (AAA) based on a 6-year experience in endovascular grafting. METHODS: From August 1994 to May 2000, 520 patients with AAA were deemed candidates for endovascular therapy based on data from contrast-enhanced computed tomography and aortography. Any conversions were performed using an open operation modified according to the indication for conversion, elapsed time from the endoluminal repair, and type of endograft (tube, bifurcated, infra-/suprarenal fixation). RESULTS: Conversion to open repair was required in 37 (7.1%) cases: 23 tube grafts and 14 bifurcated devices. Seventeen (3.2%) conversions occurred at the original operation and 20 (3.8%) were performed secondarily. Indications for primary conversion were mainly device defects (n = 5) or access problems (n = 5), while secondary conversion was primarily owing to type I endoleak (n = 16). The conversion rate was significantly higher in modular devices (5.9%) than unibody designs (1.4%) (p = 0.003). The rate of primary conversions diminished from 10.9% in 1994-1995 to 2.4% between 1996 and 2000, as did the overall mortality rate, from 8.3% in the first time period to 0% in the second for elective conversions, but emergency operations had 40% mortality. CONCLUSIONS: Most AAAs require bifurcated devices for complete exclusion, and older model modular grafts have higher conversion rates. Primary conversion decreases as more experience in endoluminal grafting is acquired. Emergency open repair results in a high mortality rate.

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