Entire Vessel Wall Research Articles

Histopathologic Features of the Popliteal Artery Entrapment Syndrome

Surgically occluded popliteal arteries, resected from five patients with clinical and radiologic evidence of the popliteal entrapment syndrome, were examined histologically. Degenerative changes and neovascularization appear to be the initial changes in the adventitia of the artery, which then seem to progress to involve the entire vessel wall. Three distinct stages of progression were identified. Stage 1 is the earliest phase, comprising neovascularization of the adventitia, with no medial fibrosis or destruction. In stage 2 there is transmural vascular proliferation with accompanying fibrous replacement of the media. Stage 3 shows similar neovascularization, with extensive fibrous replacement of the media, fragmentation of the internal elastic lamina, and extensive fibrointimal proliferation, with superimposed thrombus. Recognition of each of the varying stages allows for distinction of this uncommon condition from other clinical mimics of an acutely threatened lower limb.

Pre-eclampsia associated alterations of the elastic fibre system in umbilical cord vessels.

Although pre-eclampsia (PE) is often associated with fetal hypoxia, hypertension and/or disturbed function of the fetal circulation, the effect of these altered hemodynamic parameters on the structure and composition of umbilical vessels has not been systematically investigated before. Therefore, this study focuses on PE-associated changes of the elastic fibre system in umbilical cord vessels investigated by light and electron microscopy, immunocytochemistry and biochemistry. In umbilical cord veins, no changes in thickness of the vessel wall or of any sublayer were observed. However, the internal elastic lamina of the veins was split in 80% of the PE-group in contrast to 20% in uncomplicated pregnancies. This effect was significant (alpha <0.01) from 36 weeks of gestation onwards. In umbilical cord arteries, the entire arterial vessel wall was found to be 15% thicker in PE than in uncomplicated pregnancies. The enlargement was caused by an increase of both the tunica intima and tunica media. The thickening of the tunica intima was attributed to a migration of smooth muscle cells towards the endothelium, accompanied by a splitting of the internal elastic lamina. Compared to uncomplicated pregnancies, smooth muscle cells of arteries and veins in PE showed a metabolic activation demonstrated by highly dilated endoplasmic reticulum. A semiquantitative score method as well as a quantitative dot blot assay indicated a PE-associated reduction of elastin expression in the arterial vessel walls. In summary, PE obviously induces a decrease of the elastin content accompanied by a thickening of the vessel wall in umbilical cord arteries. This remodeling of the elastic fibre system, together with an increased migration of smooth muscle cells, might represent part of the functional adaptation system of the umbilical cord arteries on the altered hemodynamic conditions in PE.

Serum amyloid A is present in the capillaries and microinfarcts of hypertensive monkey brain: An immunohistochemical study

Serum amyloid A (SAA) is a major inducible acute phase protein characterized as a transient injury specific constituent of high density lipoprotein. We investigated whether the acute phase SAA (A-apoSAA), as a marker of inflammation, is present in the brain of monkeys with surgically induced hypertension of 39 months duration. Sections from brains of normotensive monkeys (systolic blood pres-sure< 124 mmHg) and hypertensive monkeys (systolic blood pressure> 185 mmHg) were processed for immunohis-tochemistry with a rabbit polyclonal antiserum to human A-apoSAA. We found that A-apoSAA was present in hypertensive but not in normotensive brain sections. Staining was localized to capillary endothelial cells and occasionally to the entire vessel wall of the prefrontal cortex. Staining was also observed in the capillaries and in medium size vessels of the corona radiata, the head of the caudate and, to a smaller extent, in theputamen. Additionally, the A-apoSAA was present in cells forming a circular configuration within microinfarcts. These findings suggest that high blood pressure in the brain can result in either local production of A-apoSAA in the capillaries and within microinfarcts or uptake of A-apoSAA from the blood.

A new approach for local intravascular drug delivery. Iontophoretic balloon.

Catheter-based systems are being developed to deliver drugs directly into the vessel wall. Pressure-mediated trauma and lack of homogeneous delivery are key limitations of these approaches. We studied a new catheter-based delivery system that uses electrical current to force the drug into the vessel wall. The in vivo feasibility of this approach has been assessed by delivering 125I-hirudin into porcine carotid arteries. Vascular levels of hirudin after active iontophoresis (4 mA/cm2, 5 minutes) were 80-fold greater than those achieved by passive diffusion (without electricity). Tissue hirudin levels declined over time; by 1 hour after delivery, 80% of the drug had left the vessel wall, and by 3 hours later, the levels of hirudin within the wall were similar to those achieved by passive diffusion. Autoradiography revealed distribution of the drug throughout the entire circumference of the arterial wall within the intima, media, and adventitia. Iontophoresis-mediated vessel wall trauma was minimal (less than 10% endothelial denudation and medial smooth muscle cell damage). Balloon injury after local delivery changed neither kinetics nor distribution of the drug into the arterial wall. (1) High local concentrations of hirudin in the arterial wall may be achieved with the iontophoretic balloon catheter. (2) The drug is distributed throughout the entire vessel wall without significant damage. (3) The retention of hirudin in the arterial wall is time dependent. (4) This technique might be useful to deliver therapeutic agents before or after percutaneous vascular interventions.

Intravascular Ultrasound Imaging

Intravascular Ultrasound Imaging contains a clear overview of the basics of intravascular ultrasound physics with helpful details to avoid problems when starting out with this imaging modality. The authors present how-to techniques and discuss the advantages and pitfalls of three-dimensional reconstruction and its future applications. Drs Cavaye and White argue that the advantage of intravascular ultrasound is that it provides the best visualization of the entire vessel wall and mural distribution of pathologic characteristics. Their argument is supported by many excellent detailed illustrations of ultrasound images defining mural abnormalities. Although not specifically stated, implicit in the monograph is that the true potential of ultrasound for better tissue characterization will be achieved when ultrasound equipment manufacturers accept the possibilities of improved imaging with three-dimensional reconstruction and allow access to proprietary information for reconstruction. This monograph should not be ignored by those who do not practice intraluminal vascular procedures. It

Ultrastructural characteristics of spasm in intracerebral arterioles.

Following craniotomy, three groups of cats were subjected to three different stimuli: group A hyperventilation, group B electroshock, and group C direct electric current. During electric stimuli, pial vessels were observed through a cranial window. Immediately after electric current application, some arterial vessels showed segmental spastic constriction. Tissue samples for electron-microscopy were taken from the parietal lobe and nucleus caudatus. In all three groups of animals, different types of constriction of blood vessels were observed. The respiratory alkalosis achieved by hyperventilation led to physiological constriction of the arterioles. The electric stimuli led to spastic constriction of the meningeal and intracerebral arteries and arterioles in group B and C; the entire vessel wall was greatly deformed and the vessel lumen was almost obstructed. Electroshock resulted in only moderate structural changes of the smooth muscle cells. Direct current, however, caused an extreme and bizarre smooth muscle deformation. The results show that spastic constrictions of arterioles can be clearly distinguished from physiological, that is non-spastic constriction, by morphological parameters. Electric stimulation of cerebral vessels could be an experimental condition for further investigation of intracerebral vasospasm.

Entstehung einer besonderen Form der »polypoiden Polster» und klappenähnlicher Bildungen in Arterien

Intraarterial structures, known as 'polypoid cushions' and 'valve-like' projections at arterial branching sites, were observed in serial sections of human cleft lip and nasal mucous membrane biopsies. A particular type of 'polypoid cushions', which additionally contains a small artery in its center, is distinguished. It is suggested that both the particular type of 'polypoid cushions' and these 'valve-like' projections originate from the invagination of the entire vessel wall at arterial branching sites according to the location of the dissection or damage. The differences between these 'valve-like' formations and genuine arterial valves are mentioned.