Noninvasive imaging of the coronary arteries

A reliable noninvasive imaging method for significant coronary artery stenosis would have enormous implications related to cost of diagnosis and enhanced patient safety. Cardiac motion and calcified plaques, in the past, rendered a substantial number of computed tomographic (CT) images of the coronary arteries uninterpretation. The accuracy of multidetector CT for the detection of coronary stenosis appears to have progressively improved as the imaging equipment increased from 4-slice and 16-slice to 64-slice CT. With 64-slice CT, scanning of the entire coronary artery tree is possible in 10 to 13 s. Pooled data of results of a few investigations with 64-slice CT showed that the proportion of unevaluable segments is only 4%. The sensitivity of 64-slice CT for the detection of significant (>50% or = or >50%) coronary stenosis in a patient, based on pooled data, was 97% and specificity was 91%. Regarding detection of significant stenosis in any segment, the sensitivity, based on pooled data, was 91% with 64-slice CT and specificity was 96%. In a limited number of patients, sensitivity for detection of significant stenoses in proximal segments was 100%, in mid segments it was 94%, and in distal segments sensitivity it was 80%. Multi-detector CT provides the opportunity to quantify non-calcified coronary artery plaques, which may potentially be a strong predictor of cardiac events. It was also shown to be useful for the detection of stenosis in coronary artery bypass grafts.

Comparison of anthropometric, area- and volume-based assessment of abdominal subcutaneous and visceral adipose tissue volumes using multi-detector computed tomography

PURPOSE

Cross-sectional imaging may enable accurate localization and quantification of subcutaneous and visceral adipose tissue. The reproducibility of multi-detector computed tomography (MDCT)-based volumetric quantification of abdominal adipose tissue and the ability to depict age- and gender-related characteristics of adipose tissue deposition have not been reported.

METHODS

We evaluated a random subset of 100 Caucasian subjects (age range: 37-83 years; 49% women) of the Framingham Heart Study offspring cohort who underwent MDCT scanning. Two readers measured subcutaneous and visceral adipose tissue volumes (SAV and VAV; cm(3)) and areas (SAA and VAA; cm(2)) as well as abdominal sagital diameter (SD) and waist circumference (WC).

RESULTS

Inter-reader reproducibility was excellent (relative difference: -0.34+/-0.52% for SAV and 0.59+/-0.93% for VAV, intra-class correlation (ICC)=0.99 each). The mean SAA/VAA ratio was significantly different from the mean SAV/VAV ratio (2.0+/-1.2 vs 1.7+/-0.9; P<0.001). The ratio of SAV/VAV was only weakly inversely associated with SD (ICC=-0.32, P=0.01) and not significantly associated with WC (ICC=-0.14, P=0.14) or body mass index (ICC=-0.17, P=0.09). The mean SAV/VAV ratio was significantly different between participants <60 vs >60 years (1.9+/-1.0 vs 1.5+/-0.7; P<0.001) and between men and women (1.2+/-0.5 vs 2.2+/-0.9; P<0.001).

CONCLUSION

This study demonstrates that MDCT-based volumetric quantification of abdominal adipose tissue is highly reproducible. In addition, our results suggest that volumetric measurements can depict age- and gender-related differences of visceral and subcutaneous abdominal adipose tissue deposition. Further research is warranted to assess whether volumetric measurements may substantially improve the predictive value of obesity measures for insulin resistance, type 2 diabetes mellitus and other diseases.

A VEGF-A splice variant defective for heparan sulfate and neuropilin-1 binding shows attenuated signaling through VEGFR-2

The development of functional blood and lymphatic vessels requires spatio-temporal coordination of the production and release of growth factors such as vascular endothelial growth factors (VEGFs). VEGF family proteins are produced in multiple isoforms with distinct biological properties and bind to three types of VEGF receptors. A VEGF-A splice variant, VEGF-A(165)b, has recently been isolated from kidney epithelial cells. This variant is identical to VEGF-A(165) except for the last six amino acids encoded by an alternative exon. VEGF-A(165)b and VEGF-A(165) bind VEGF receptors 1 and 2 with similar affinity. VEGF-A(165)b elicits drastically reduced activity in angiogenesis assays and even counteracts signaling by VEGF-A(165). VEGF-A(165)b weakly binds to heparan sulfate and does not interact with neuropilin-1, a coreceptor for VEGF receptor 2. To determine the molecular basis for altered signaling by VEGF-A(165)b we measured VEGF receptor 2 and ERK kinase activity in endothelial cells in culture. VEGF-A(165) induced strong and sustained activation of VEGF receptor 2 and ERK-1 and -2, while activation by VEGF-A(165)b was only weak and transient. Taken together these data show that VEGF-A(165)b has attenuated signaling potential through VEGF receptor 2 defining this new member of the VEGF family as a partial receptor agonist.

Pretransplant calcium levels have no predictive value for delayed graft function, long-term graft function, cardiovascular events, or graft and patient survival in renal transplantation

BACKGROUND

Disorders of calcium homeostasis are one of the most common problems in patients with end-stage renal disease (ESRD). Elevated calcium levels increase the incidence of cardiovascular mortality in ESRD patients, and appear to be a risk factor for the occurrence of delayed graft function (DGF) after kidney transplantation. Therefore, we investigated the impact of pretransplant serum calcium levels on outcomes after kidney transplantation: DGF, acute rejection, graft function, and survival, as well as the incidence of cardiovascular events.

METHODS

We studied 285 patients (96.9% of all transplanted patients) who underwent their first transplantation between 1995 and 2004. Demographic data were extracted from hospital records or were documented during follow-up; serum samples were collected at the time of transplantation.

RESULTS

In our cohort the incidence of DGF was 16.5% and 35.4% of acute rejection episodes (ARE). However, pretransplant calcium levels were not related to DGF or ARE in our patient cohort. Furthermore, there was no correlation between pretransplant serum calcium level with the incidence of cardiovascular events or mortality, as well as graft function or survival.

CONCLUSION

In our study population pretransplant calcium levels showed no effect on DGF, ARE rate, the occurrence of cardiovascular events or death, renal graft function, or survival. Therefore, pretransplant calcium level is not a helpful marker for risk stratification at the time of transplantation.

Takayasu-Arteriitis ohne manifeste Gefäßstenosen als Ursache von Fieber unklarer Genese

HISTORY AND CLINICAL FINDINGS

Two women, aged 59 and 53 years, presented with a history of several months of classical fever of unknown origin (FUO), largely normal physical findings, and elevated markers of systemic inflammation.

INVESTIGATIONS

After initially unremarkable findings, duplex-sonography detected circular, hypoechogenic wall thickening of the axillary arteries without hemodynamically significant narrowing of the lumen. 18F-fluorodeoxyglucose positrone emission-tomography (18F-FDG-PET) revealed marked vascular tracer uptake in the aorta and in the proximal arteries of the arms and legs. TREATMENT AND FOLLOW-UP: The diagnosis of Takayasu's arteritis was made, and high-dose prednisone treatment was initiated. Within a few days both patients became asymptomatic.

CONCLUSIONS

Large vessel vasculitis is a known cause of FUO. Duplex-sonography and 18F-FDG-PET are able to detect these disorders at an early stage before the onset of clinically relevant arterial obstructions. More widespread use of these techniques may show that large-vessel vasculitis is more common than previously thought.

Aspirin in peripheral arterial disease: breakthrough or pitfall?

Background: This paper introduces a proof-of-concept trial in progress, supposedly providing new important information on anti-platelet drugs used in patients with peripheral arterial disease (PAD). The Arteriogenesis Competence Network (Art.Net.) of the Universities of Basel, Berlin, and Freiburg could show in animal models that Aspirin (ASA), in contrast to Clopidogrel, inhibits the formation of an appropriate collateral network (arteriogenesis). This trial is supposed to reproduce the animal data in man. Materials and methods: In a prospective, double-blind, parallel-group, bi-national (D, CH), multicentre trial, 250 patients will be randomised to either 100 mg ASA or 75 mg Clopidogrel once daily. Patients will then enter a three months structured rehabilitation programme with daily physical training supposed to induce arteriogenesis. The claudication distances will be tested as the primary endpoint at baseline, 6 weeks, and at 3 months. Also, the 24h physical activity profile of all patients will be electronically documented. Conclusions: This trial will provide information on potential disadvantages when using ASA in PAD patients. If data emerging from animal pharmacology can be reproduced in man, the present standard scheme of anti-aggregant treatment in PAD patients has to be reconsidered.

Noninvasive detection of coronary atherosclerotic plaque by multidetector row computed tomography

BACKGROUND

Coronary artery disease continues to be one of the leading causes of death and disability around the globe, challenging the efficacy of currently applied schemes to predict the risk for future coronary events. In fact, algorithms such as the Framingham risk score that are based on traditional risk factors like hypertension and dyslipidemia are not very sensitive, leaving a majority of the population at intermediate risk.

METHODS

Advances in multidetector computed tomography (MDCT) technology with submillimeter slice collimation (approximately 0.6 mm) and high temporal resolution now permit contrast-enhanced imaging of the coronary artery lumen and wall in a single breath hold. The current generation of MDCT provided in-plane resolution of 0.5 mm and a temporal resolution of 210 ms. The simultaneous acquisition of 16/64 parallel cross-sections reduces image acquisition time to about 10-20s using 60-80 ml of contrast agents to opacify the coronary artery lumen. CT imaging for coronary calcification is an established method with low radiation exposure. The amount of calcification is expressed as an Agatston Score (AS).

RESULTS

The presence and amount of coronary calcification significantly increases the relative risk for future coronary events, independent from traditional risk factors (risk ratio 8.7 [95% Cl, 2.7-28.1]). Especially, individuals with a high AS (>400) who are at intermediate 10-y Framingham event risk may benefit from this additional risk stratification. However, calcification is rarely present in children and adolescents. However, there is a growing body of evidence suggesting that contrast-enhanced MDCT can detect both calcified and noncalcified plaques with high sensitivity and specificity for the detection of plaques > 0.5 mm when compared to intravascular ultrasound. Moreover, initial data suggest that plaque characteristics such as plaque area, volume, quantify and coronary plaque remodeling index can be quantified in good agreement with IVUS. The composition of noncalcified plaque may be further stratified into predominantly fibrous or lipid-rich plaque. Noncalcified plaque may be present already in children and adolescents with multiple risk factors.

CONCLUSION

The available data indicate that high resolution MDCT can reliably detect, quantify and characterize calcified and noncalcified coronary atherosclerotic plaque. With MDCT, we now have a unique opportunity to study the natural history and response to therapy of noncalcified coronary plaques, which may be already present in obese children or children with multiple risk factors.

Stenting of the superficial femoral artery after suboptimal balloon angioplasty: one-year results

AIM

The aim of this study was to analyze the intermediate results of selective stenting of superficial femoral artery (SFA) lesions after a suboptimal balloon angioplasty result.

METHODS

We analyzed 70 consecutive patients with claudication or critical limb ischemia due to peripheral arterial occlusive disease who underwent stent implantation of the SFA after unsuccessful balloon-angioplasty. All patients were followed-up immediately after the procedure and 3, 6 and 12 months thereafter. Restenosis was defined as an increase of peak systolic velocity-index >2 as determined by duplex sonography.

RESULTS

Primary patency rates at 3, 6 and 12 months were 83.4%, 66.2% and 59%, respectively. Successful reinterventions were performed for 17 reobstructions, resulting in a secondary patency rate at 3, 6 and 12 months of 91%, 89.3%, and 83.8%, respectively. At 12 months 68.6% of the patients were asymptomatic, 21.6% complained of mild (Fontaine class II a), 5.9% of severe (Fontaine class II b) claudication and 2.9% were in critical limb ischemia.

CONCLUSIONS

Our data indicate that selective stenting of the SFA after suboptimal balloon angioplasty results in intermediate patency rates similar to that reported for primarily successful PTA, thereby supporting the widely accepted policy of selective stenting as a rescue procedure after unsuccessful balloon angioplasty.

Expression of cyclooxygenase-1 and cyclooxygenase-2 in human renal allograft rejection - a prospective study

Cyclooxygenases (COX) are known to be involved in inflammatory kidney diseases. However, there are no data available about the expression of COX-1 and only preliminary reports about the expression of COX-2 in biopsies of patients undergoing acute renal allograft rejection. We conducted this prospective study to analyze the expression, distribution, and cellular localization of COX-1 and -2 and thus to elucidate the role of COX in human kidney transplantation. One hundred forty-four biopsies were included from patients without rejection and unaltered morphology (n = 60), with acute interstitial rejection (n = 7), with acute vascular rejection (n = 21), with chronic allograft nephropathy (n = 16), without rejection but with various other lesions (n = 40). COX-1 and -2 expression was localized in each biopsy by immunohistochemistry. We found a highly significant up-regulation of COX-1 in vessels and in infiltrating interstitial cells of patients with acute allograft rejection compared with biopsies with well-preserved tissue. Also, COX-2 expression was significantly elevated in infiltrating interstitial cells of biopsies with acute rejection. This is the first prospective study demonstrating a significant induction of both COX-1 and -2 in human allograft biopsies with acute rejection after renal transplantation.

Expression of the chemokine receptor CXCR3 in human renal allografts—a prospective study

BACKGROUND

Mechanisms involved in the recruitment and activation of inflammatory cells during renal allograft injury are still incompletely understood. Since chemokines play pivotal roles in this process, our prospective study was performed to evaluate further the role of the chemokine receptor CXCR3.

METHODS

A total of 138 biopsies were included from patients without rejection and unaltered morphology (according to Banff 97 classification grade 1, n = 49), with acute interstitial rejection (Banff grade 4 type I, n = 8), with acute vascular rejection (Banff grade 4 type II, n = 23), with chronic allograft nephropathy (Banff grade 5, n = 16), without rejection but with various other lesions (Banff grade 6, n = 36) and from pre-transplant kidneys (n = 6). The expression of CXCR3-, CD4- and CD8-positive cells was localized by immunohistochemistry and quantified by image analysis.

RESULTS

CXCR3 was expressed by infiltrating inflammatory cells, but not by intrinsic renal structures. CXCR3-positive cells were found to be involved in tubulitis and vascular rejection. The area of CXCR3-positive staining was significantly larger in biopsies with acute interstitial rejection (P<0.001) and acute vascular rejection (P<0.001) as compared with normal renal graft biopsies. There was a strong morphological and numerical correlation between CXCR3 and both CD4- and CD8-positive T cells, respectively.

CONCLUSIONS

A significant part of both CD4- and CD8-positive T cells express the chemokine receptor CXCR3. During renal allograft rejection, the number of these cells increases significantly at the site of injury and might be targeted by CXCR3 blocking agents.

Refractory Takayasu's arteritis successfully treated with the human, monoclonal anti-tumor necrosis factor antibody adalimumab

Treatment of Takayasu's arteritis remains a demanding challenge to clinicians. In many patients the course of the disease is characterized by frequent relapses and disease progression under conventional treatment with glucocorticoids and cytotoxic drugs. We present the case of a young woman with severe cerebrovascular and aortic involvement, who experienced disease progression in spite of more than 2 years of treatment with high doses of prednisone, methotrexate and cyclophosphamide. In this patient, treatment with the human, monoclonal anti-tumor necrosis factor-alfa (TNFalfa)-antibody adalimumab achieved clinical remission and allowed tapering of prednisone within a few months. The present case, as well as previous reports on the use of infliximab in giant cell and Takayasu's arteries, suggests that TNFa-blockade may be a new, promising treatment for glucocorticoid-refractory large-vessel vasculitis.

Cardiovascular Responses to Apnea during Dynamic Exercise

Breath holding maneuvers induce hypoxia, hypercapnia, and various cardiovascular responses typically including increases in total peripheral resistance, mean arterial pressure (MAP) and decreases in heart rate (HR). During dynamic exercise these responses may have a generally negative impact on performance. Moreover, they deserve particular attention in cardiovascular risk subjects. In 26 healthy sport students we studied the HR and MAP effects induced by the combination of dynamic exercise (cycle ergometry, 30 W and 250 W) with 20 s of either respiratory arrest (mouth piece pressure held constant at 20 mm Hg), free breathing, or rebreathing, i. e. periods of unimpeded breathing leading to similar levels of hypercapnia and hypoxia as the respiratory arrest. The measurements yielded no major differences between the conditions of rebreathing and free breathing. In contrast, 20 s of apnea led to a marked increase in MAP and a HR depression at both levels of exercise intensity. Additionally, there was a delayed MAP recovery after this stimulus. The present findings show that breath holding has marked effects on MAP and HR during dynamic exercise, which are essentially independent of the resulting hypoxia and of increases in intrathoracic pressure. The key factor seems to be an increase in total peripheral resistance, probably including a vasoconstriction in the exercising muscles.

Renal effects of gadopentetate dimeglumine in patients with normal and impaired renal function

Gadolinium chelates are widely used in magnetic resonance imaging as contrast medium in patients with nephropathy. However, only few studies have investigated the effect of gadolinium on serum creatinine concentration and estimated GFR as surrogate markers of renal function. This study was performed to evaluate the effect of gadopentetate dimeglumine in a dose sufficient for diagnostic and interventional purposes on renal function in a large sample of patients. We analyzed serum creatinine and serum-urea levels before and after the administration of gadopentetate dimeglumine in patients with normal and patients with pre-existing impaired renal function. Age, height, body mass, sex, medication and preexisting illnesses such as diabetes, renal artery stenosis and heart disease were monitored. In 181 patients with normal renal function, there was no statistically significant change in serum creatinine concentration after the administration of gadopentetate dimeglumine (at baseline: 0.72 +/- 0.18 mg/dl, after gadolinium: 0.73 +/- 0.22 mg/dl). In contrary, serum creatinine levels decreased significantly after the administration of gadolinium in 198 patients with pre-existing renal impairment (1.82 +/- 1.03 mg/dl before and 1.72 +/- 1.03 mg/dl after gadolinium) (p < 0.01). According to this surrogate marker of renal function, the change of estimated GFR in patients with normal baseline renal function was not significant, while in patients with impaired renal function, GFR increased after the administration of gadolinium (p < 0.001). The high diagnostic value of gadolinium contrast media is associated with a very small risk of adverse reactions. Our findings show that the administration of gadolinium even is associated with a decrease of serum creatinine in patients with pre-existing renal impairment. In conclusion, the use of gadolinium-based contrast media may be considered as a safe alternative in patients with impaired renal function for whom use of iodine-based contrast agents is prone to a high rate of radiocontrast-induced nephropathy.

Drotrecogin alfa (activated) inhibits NF-kappa B activation and MIP-1-alpha release from isolated mononuclear cells of patients with severe sepsis

OBJECTIVE AND DESIGN

Non-anticoagulant biological activities, such as anti-inflammatory and anti-apoptotic mechanisms of action, have been suggested for recombinant human activated protein C (rhAPC; drotrecogin alfa (activated)). However, these mechanisms are much less characterized and understood than rhAPC's anticoagulant activity. Aim of the study was to determine the effect of rhAPC on the activity of the pro-inflammatory transcription factor nuclear factor kappa B (NF-kappaB) in mononuclear cells isolated from septic patients and to characterize an effect downstream from NF-kappaB activation, such as the release of the NF-kappaB-controlled chemokine Macrophage Inflammatory Protein-1-alpha (MIP-1-alpha).

SUBJECTS

Peripheral blood was obtained from 13 septic patients and from 8 healthy controls.

METHODS

Mononuclear cells were isolated by Ficoll-Paque density gradient centrifugation and were incubated with or without rhAPC (10 microg/ml) for 2 h for the measurement of NF-kappaB activity in cell lysates or alternatively for 6 h for the determination of MIP-1-alpha levels in supernatants. NF-kappaB activity was measured by an ELISA-based assay directed against the p50 and the p65 subunit of NF-kappaB.

RESULTS

RhAPC, at supra-pharmacological concentration (10 microg/ml), significantly inhibited NF-kappaB activity and the release of MIP-1-alpha ex vivo in isolated mononuclear cells from patients with severe sepsis. In mononuclear cells of healthy subjects, however, rhAPC did not change NF-kappaB activity. Basal NF-kappaB activity early in severe sepsis was not predictive for survival.

CONCLUSIONS

RhAPC at supra-pharmacological concentration (10 microg/ml) inhibits the activity of NF-kappaB in ex vivo isolated mononuclear cells of septic patients as well as the release of MIP-1-alpha, a proinflammatory chemokine regulated by NF-kappaB. These findings may represent immunomodulatory pathways by which rhAPC exerts specific anti-inflammatory activity in vitro in addition to its known anticoagulant and profibrinolytic activity and should be further investigated in an in vivo setting.

Bacterial biofilm within diseased pancreatic and biliary tracts

BACKGROUND

Bacterial community structures in human pancreatic and biliary tracts were evaluated.

METHODS

Gall bladder stones from 153 patients, 20 gall bladder walls, six common duct stones, 52 biliary stents, 21 duodenal biopsies, nine pancreatic duct biopsies, and five bile ducts were investigated using fluorescence in situ hybridisation (FISH) with ribosomal RNA targeted Cy3/Cy5 (carbocyanine) labelled oligonucleotide probes.

RESULT

Duodenal, gall bladder, and bile duct walls were free of bacteria. A dense multispecies bacterial biofilm was present within the pancreatic duct of patients with calcific pancreatitis and within biliary stents, irrespective of diagnosis. The concentration, density, and amenability of the biofilm to FISH and DNA staining declined progressively with the grade of stent occlusion. The lowest detectable bacterial concentrations were found by FISH in completely occluded stents and brown/mixed gall stones. Bacteria were not detectable with FISH in cholesterol gall stones.

CONCLUSIONS

A wide range of different branches and groups of bacteria participate in the development of biofilms on the surfaces of foreign bodies, such as biliary stents, mixed gall stones, or calcific pancreatic ducts, but not on the surface of pure cholesterol gall stones. Occlusion of stents leads to progressive extinction of the biofilm and mummification of its components. Deposition of cholesterol or other substances within the biofilm matrix may be a novel mechanism of host defence against bacteria present in these biofilms.

Mild hyperhomocysteinemia: risk factor or just risk predictor for cardiovascular diseases?

Elevated plasma levels of homocysteine (hyperhomocysteinemia) are increasingly recognized as a potential risk for atherothrombotic vascular diseases by numerous epidemiological and clinical studies. There are increasing experimental data that indicate mechanisms by which homocysteine may alter the vasculature in a way that predisposes to atherosclerotic vascular disease. A key event in the vascular pathobiology of hyperhomocysteinemia seems to involve the induction of endothelial dysfunction due to a reduction of the endogenous antiatherothrombotic molecular nitric oxide. Elevated homocysteine levels can be efficiently and safely reduced in most of hyperhomocysteinemic patients by supplementation of folic acid and cobalamin. This reduction is associated with an improvement in endothelial function and other surrogate markers of atherothrombosis, like carotid plaque area and the rate of abnormal stress electrocardiograms. Whether or not this translates into clinical benefits, is still under investigation. The first clinical study on homocysteine-lowering vitamin supplementation in patients that had undergone coronary intervention showed a benefitial effect on the rate on restenosis and the need for revascularization which translated into a reduction of major coronary events. In contrast, in three larger scaled secondary intervention trials in patients with stable coronary disease or post non-disabling stroke, vitamin supplementation had no effect on future vascular events although baseline homocysteine levels were significantly associated with a worse prognosis. Until the results of more clinical trials are available, the clinical relevant question whether or not homocysteine is just a risk predictor or a modifiable risk factor can not definitely be answered.

Acute limb ischemia after femoral arterial closure with a vascular sealing device: Successful endovascular treatment

We report on successful catheter therapy of acute occlusions of popliteal and crural arteries due to distal embolization from a vascular sealing device. A 45 years-old male patient underwent percutaneous coronary angiography. After primary successful closure of the right femoral artery by a sealing device the patient developed acute ipsilateral lower limb ischemia, most probably due to embolization of a collagen/thrombin plug. Occlusions of the popliteal and crural vessels were successfully treated by percutaneous thrombectomy, thrombolysis and ballon angioplasty. Combined percutaneous catheter therapy is a therapeutic option for occlusions of popliteal and crural vessels due to embolization from a vascular sealing device.