P.J.E.H.M. Kitslaar

Biphasic pattern of cell turnover characterizes the progression from fatty streaks to ruptured human atherosclerotic plaques

OBJECTIVEnTo study the amount and phenotype of DNA-synthesizing and apoptotic cells during atherogenesis.nnnMETHODSnAtherosclerotic lesions (n = 76), obtained at autopsy (N = 6) or during vascular surgery (N = 8), were classified [type I-VI; American Heart Association (AHA) classification], immunolabeled with MIB 1 or the TUNEL technique and double stained with cell-type-specific antibodies. Subsequently, the labeled fractions were quantified.nnnRESULTSnIn type II-VI lesions, intimal DNA synthesis was increased compared to that of the non-diseased (ND) arterial wall. DNA synthesis peaked in early type II lesions (2.7 +/- 0.5 vs. 0.02 +/- 0.02% in ND; p < 0.05), and declined to 0.7 +/- 0.2% in type V lesions (p < 0.05). Interestingly, a second peak of DNA synthesis of 1.7 +/- 0.1%, was observed in type VI (ruptured plaque) lesions. Double staining revealed that DNA synthesis was mostly confined to the macrophage-derived foam cell (51.9%). In type II lesions, 100.0% of all DNA-synthesizing cells were present in the intimal foam cell-rich area, while in advanced type III, IV and V lesions, DNA synthesis had shifted to the shoulder region (74.8, 78.5 and 68.1%, respectively). In type VI lesions, DNA synthesis was present in the area underlying the plaque rupture (52.7%). Apoptosis was only elevated in advanced type IV, V and VI lesions (0.8 +/- 0.1, 0.8 +/- 0.1 and 1.1 +/- 0.1%, respectively, vs. 0.0 +/- 0.0% in ND) and was predominant in the lipid core (90.5% in type IV lesions; 54.2% in type V lesions) or equally divided between the lipid core and the region underlying the plaque rupture (31.8 and 34.6% in type VI lesions). In type III-VI lesions, 50.0, 38.9, 42.6 and 42.8% of the TUNEL-positive cells were macrophages.nnnCONCLUSIONSnIn stable atherosclerotic lesions, DNA synthesis is an early event, while apoptosis is a late event. Ruptured plaques show a second peak of cell turnover. Lastly, cell turnover is mostly confined to the macrophage-derived foam cell.

Wall shear stress in the human common carotid artery as function of age and gender

OBJECTIVESnIt has been postulated that in the arterial system mean wall shear stress is maintained at a constant value. The present study was performed to investigate the level of wall shear stress in the common carotid artery (CCA) as function of age and possible interactions between diameter and storage capacity, defined as the absolute area change per heart beat, with mean wall shear stress.nnnMETHODSnWall shear stress (wall shear rate multiplied by whole blood viscosity) was assessed in the right CCA of 111 presumed healthy male (n = 56) and female (n = 55) volunteers, varying in age between 10 and 60 years. Wall shear rate was measured with a high resolution ultrasound system. Simultaneously, arterial diameter and storage capacity were determined. Whole blood viscosity was calculated from haematocrit, plasma viscosity and shear rate.nnnRESULTSnFrom the second to the sixth age decade peak wall shear stress was significantly higher in males than in females and decreased from 4.3 Pa to 2.6 Pa (r = -0.56, p < 0.001) in males and from 3.3 Pa to 2.5 Pa (r = -0.54, p < 0.001) in females. Mean wall shear stress tended to decrease from 1.5 Pa to 1.2 Pa (r = -0.26, p = 0.057) in males and decreased significantly from 1.3 Pa to 1.1 Pa (r = -0.30, p = 0.021) in females. No significant difference in mean wall shear stress was found between males and females in any age decade. The diameter of the CCA increased significantly in both males (r = 0.26, p < 0.05) and females (r = 0.40, p < 0.003). Storage capacity decreased significantly in both sexes (males: r = -0.63, p < 0.001; females: r = -0.68, p < 0.001).nnnCONCLUSIONSnThese observations suggest that the reduction in mean wall shear stress with age results from the concomitant increase in diameter in an attempt of the arterial system to limit the reduction in storage capacity of the arterial system with increasing age.

Multicenter randomized controlled trial of the costs and effects of noninvasive diagnostic imaging in patients with peripheral arterial disease: The DIPAD trial

OBJECTIVEnThe purpose of our study was to compare the costs and effects of three noninvasive imaging tests as the initial imaging test in the diagnostic workup of patients with peripheral arterial disease.nnnMATERIALS AND METHODSnOf 984 patients assessed for eligibility, 514 patients with peripheral arterial disease were randomized to MR angiography (MRA) or duplex sonography in three hospitals and to MRA or CT angiography (CTA) in one hospital. The outcome measures included the clinical utility, functional patient outcomes, quality of life, and actual diagnostic and therapeutic costs related to the initial imaging test during 6 months of follow-up.nnnRESULTSnWith adjustment for potentially predictive baseline variables, the learning curve, and hospital setting, a significantly higher confidence and less additional imaging were found for MRA and CTA compared with duplex sonography. No statistically significant differences were found in improvement in functional patient outcomes and quality of life among the groups. The total costs were significantly higher for MRA and duplex sonography than for CTA.nnnCONCLUSIONnThe results suggest that both CTA and MRA are clinically more useful than duplex sonography and that CTA leads to cost savings compared with both MRA and duplex sonography in the initial imaging evaluation of peripheral arterial disease.

Chlamydophila pneumoniae (Chlamydia pneumoniae) accelerates the formation of complex atherosclerotic lesions in Apo E3-Leiden mice

OBJECTIVEnAtherosclerosis is an inflammatory process and is characterised by the presence of T-lymphocytes in the lesions. To study the role of Chlamydophila pneumoniae (C. pneumoniae) in this process and the effect of infection on T-cell influx, we infected Apo E3-Leiden mice with C. pneumoniae and investigated the effect on lesion development and T-cell influx in atherosclerotic lesions at different time points post infection (pi).nnnMETHODSnNine week old mice, fed an atherogenic diet, were either mock-infected or infected with C. pneumoniae and sacrificed at 1, 6 and 9 months pi. Longitudinal sections of the aortic arches of the mice were stained with hematoxylin-eosin for atherosclerotic lesion type and lesion area analysis, or with rabbit-anti-CD3(+) to detect the presence of T-cells in the atherosclerotic lesions. T-cell influx was expressed as number of T-lymphocytes/lesion area.nnnRESULTSnAt 1 month pi, type 1, 2 and 3 lesions were present. At other time points pi, more complex lesion types 4, 5a and 5b were also present. Although infection did not influence the total lesion number or area, we observed an effect of C. pneumoniae infection on lesion type. Infection resulted in a significant shift in lesion formation from type 3 to type 4 (P=0.022) at 6 months pi, and from type 4 to type 5a (P=0.002) at 9 months pi. T-cells were observed at every time point pi. At 1 month pi, a significant increase in T-cell influx in the C. pneumoniae-infected atherosclerotic lesions was observed (P=0.0005).nnnCONCLUSIONnThis study shows that C. pneumoniae infection enhances the inflammatory process by increasing T-lymphocytes in the plaque and accelerates the formation of complex lesions.

Reproducibility of shear rate and shear stress assessment by means of ultrasound in the common carotid artery of young human males and females

In the present study, the reliability of an ultrasonic shear rate estimating system, in terms of intrasubject intrasession, intersubject intrasession and intersubject intersession variability coefficients for the assessment of wall shear rate (WSR) in the common carotid artery (CCA) was determined in eight presumed healthy volunteers. Measurements were performed on consecutive days (day 1, day 2 and day 7). To investigate whether there were differences in WSR due to gender, dynamic WSR in the CCA was assessed in 11 presumed healthy males (mean age 24 y) and 11 presumed healthy females (mean age 25 y). Wall shear stress (WSS) was estimated from WSR and calculated whole blood viscosity. The average intrasubject intrasession variability was about 15% for peak WSR and about 12% for mean WSR. The intersubject intrasession variability for peak WSR decreased from 19% on day 1 to 16% on day 7 and for mean WSR from 17% on day 1 to 11% on day 7. The intersubject intersession variability is on the order of 5% for peak WSR and about 4% for mean WSR. No significant differences could be detected between peak and mean WSR values on day 1, day 2 and day 7, indicating good short- and medium-term intersubject intersession reproducibilities. No differences in peak and mean WSR were found between the left and the right CCA in the male group as well as in the female group. Mean WSS was similar in males (1.3 +/- 0.3 Pa) and in females (1.2 +/- 0.2 Pa), but peak WSS was slightly, but significantly, higher in males (4.3 +/- 1.3 Pa) than in females (3.3 +/- 0.7 Pa). It can be concluded that peak and mean WSR can be reliably determined noninvasively using ultrasound.

Comparison of treatment plans for peripheral arterial disease made with multi-station contrast medium-enhanced magnetic resonance angiography and duplex ultrasound scanning

OBJECTIVEnThis study was undertaken to investigate the effects of substituting multi-station total outflow contrast medium-enhanced magnetic resonance angiography (CE-MRA) for color duplex ultrasound (US) scanning on treatment planning in the diagnostic workup of patients with suspected or known peripheral arterial occlusive disease. Patients and methods One hundred consecutive patients referred because of suspected or proved peripheral arterial occlusive disease to a University Hospital underwent both aortoiliac duplex US scanning and multi-station total outflow CE-MRA. For 73 of these patients (57% men; mean age, 62 years) treatment or treatment plans could be retraced. Eighteen patients also underwent femoro-popliteal duplex US scanning. Three experienced vascular surgeons retrospectively formulated two sets of treatment plans based on standardized clinical parameters and either duplex US scanning or CE-MRA. The main outcome measure was proportion of patients for whom the treatment plan matched actual treatment without additional use of intra-arterial digital subtraction angiography. Actual treatment, based on all available information, including results of duplex US scanning, CE-MRA, and any other diagnostic tests, served as the standard of reference.nnnRESULTSnDuplex US scanning provided enough information for treatment planning in 46, 45, and 53 patients versus 67, 68, and 66 patients when CE-MRA was used (surgeons 1, 2, and 3, respectively; surgeons 1 and 2, P <.001; surgeon 3, P =.007). Treatment plans based on duplex US scanning exactly matched actual treatment in 37 of 73 patients (51%; surgeon 1), 36 of 73 patients (49%; surgeon 2), and 46 of 73 patients (63%; surgeon 3). Treatment plans based on CE-MRA exactly matched actual treatment in 56 of 73 patients (77%; surgeon 1), 55 of 73 patients (75%; surgeon 2), and 51 of 73 patients (70%; surgeon 3). Positive predictive value and negative predictive value of duplex US scanning as measures of ability to discriminate between surgical and nonsurgical treatment were 0 of 0 (undefined) and 43 of 46 (93%), 1 of 2 (50%) and 40 of 43 (93%), and 5 of 5 (100%) and 44 of 48 (92%) for surgeons 1, 2, and 3, respectively. For CE-MRA, positive and negative predictive values were 11 of 13 (85%) and 50 of 54 (93%), 10 of 12 (83%) and 51 of 56 (91%), and 8 of 13 (62%) and 48 of 53 (91%), respectively, for surgeons 1, 2, and 3.nnnCONCLUSIONnCompared with aorto-iliac and femoro-popliteal duplex US scanning, multi-station total outflow CE-MRA is more effective for treatment planning in most patients with known or suspected peripheral arterial occlusive disease.

Chlamydia pneumoniae Serology Is Associated With Thrombosis-Related but Not With Plaque-Related Microembolization During Carotid Endarterectomy

Background and Purpose— Chlamydia pneumoniae has repeatedly been associated with atherosclerotic disease. Our study was designed to clarify whether this association is based on C pneumoniae-induced transformation of a stable into an unstable atherosclerotic plaque or on stimulation of hypercoagulability leading to increased thrombotic arterial occlusions by C pneumoniae infection. Transcranial Doppler ultrasonographic monitoring of the middle cerebral artery during carotid endarterectomy offers the opportunity to study, before removal of the plaque, atherothrombotic emboli dislodging from an unstable carotid plaque (plaque-related emboli) and emboli related to (excessive) thrombus formation at the endarterectomy site after removal of the plaque and restoration of flow (thrombosis-related emboli). Methods— C pneumoniae IgA (≥1/16) and IgG (≥1/64) seropositivity was assessed in 53 patients with symptomatic carotid artery disease undergoing carotid endarterectomy. The removed carotid plaques were studied histologically to assess plaque instability. Results— Plaque- and thrombosis-related emboli were registered in 43 patients with an adequate transtemporal window. IgA seropositivity (58%) was associated significantly with thrombosis-related embolization (P =0.030) but not with plaque-related embolization or with histological plaque instability. Conclusions— C pneumoniae serology is associated with microembolization after endarterectomy and restoration of flow. Since these microemboli represent platelet aggregations and are related to cerebrovascular complications, our data suggest that C pneumoniae infection contributes to cerebrovascular events in patients with carotid artery disease through stimulation of thrombosis.

Diagnosis of abdominal aortic hypoplasia by state-of-the-art MR angiography

Abdominal aortic hypoplasia is a rare vascular variant with possible major clinical sequelae when the renal arteries are also involved. The condition is thought to result from embryonic overfusion of the two dorsal aortas. The diagnosis may be considered in patients presenting with hypertension in the neonatal period and severely reduced or absent arterial pulses in the groin. We present contrast-enhanced state-of-the-art magnetic resonance angiography imaging findings in an 8-year-old boy with abdominal aortic hypoplasia.

Usefulness and applicability of femorofemoral crossover bypass grafting.

We examined the usefulness of femorofemoral crossover bypass grafting (FFC) and factors influencing its outcome by retrospectively analyzing all FFCs performed in our hospital over a 5-year period, focusing on both patency rates and clinical efficacy. For 95 patients Kaplan-Meier patency rates were calculated (follow-up 40.4 +/- 3.0 months). Clinical outcome was defined according to Rutherfords standardized categories. The influence of cardiovascular risk factors and technical characteristics on outcome was determined. Clinical status of the limb remained improved in 89%. One- and 5-year primary, primary assisted, and secondary patency rates were 88.2% and 57.3%, 90.6% and 62.4%, and 92.6% and 68.1%, respectively. Clinical outcome of the limb was better in patients with <50% stenosis in the femoral arteries preoperatively (p = 0.033). No predictors for patency rates were identified. FFCs are effective in the medium long term for patients in all age categories independently of cardiovascular risk factors. The best predictor of clinical outcome is the preoperative degree of stenosis, with a better outcome for patients affected by <50% stenosis. Success of FFC cannot be reliably measured by graft patency alone but should be assessed by combining patency rates and clinical outcome according to standardized categories.

The new immunosuppressive agent FK778 attenuates neointima formation in an experimental venous bypass graft model

Neointima formation as a result of smooth muscle cell (SMC) proliferation still contributes significantly to venous bypass graft stenosis and failure. The new immunosuppressive agent FK778 has recently been shown to exert anti-proliferative effects. We examined the inhibitory potential of FK778 on venous SMC proliferation and neointima formation in an experimental venous bypass graft model. Quiescent venous SMCs were incubated for 48 h with 10% FCS and different concentrations of FK778. SMC proliferation was measured by Ki67 immunostaining. Uridine was added to reverse FK778 induced pyrimidine synthesis blockade. The effect of FK778 treatment on neointima formation in vivo was assessed in an autologous epigastric vein-to femoral artery interposition graft model in rats. In vitro, FK778 inhibited venous SMC proliferation in a dose dependent manner. This effect was reversed by addition of uridine. In vivo, 3-week oral treatment with FK778 (15 mg/kg/d) significantly reduced neointima formation and stenosis in venous bypass grafts. We show that the immunosuppressive agent FK778 can prevent neointima formation in experimental venous bypass grafts by inhibiting venous SMC proliferation. FK778 might provide a new pharmacological therapy to limit vein graft stenosis and bypass graft failure.