Carotid

Grafts are also frequently employed in the upper part of the body to reconstmct damaged portions of the aorta and carotid arteries. In addition, grafts are used to access the vascular system, such as in hemodialysis to avoid damage of vessels from repeated needle punctures. Most grafts are synthetic and made from materials such as Dacron or Teflon. Less than 5% of grafts utilized are made from biological materials. 

Delourme-Houdd finds that tabernanthine injected into dogs is hypotensive, decreases the rate and amplitude of respiration, reduces the reflex hypertension induced by occlusion of the carotids and, like... 

Baroreceptor. Specialized pressure-sensitive tissue located in carotid arteries. Nerve impulses proportional to arterial blood pressure are conducted from this tissue to the brain which in turn exerts control over the blood pressure. 

The baroreceptor reflex is a central reflex mechanism, which reduces heart rate following an increase in blood pressure. Each change in blood pressure is sensed by baroreceptors in the carotid arteries, which activate the autonomic nervous system to alter heart rate and thereby readjust blood pressure. 

The regulation of the total peripheral resistance also involves the complex interactions of several mechanisms. These include baroreflexes and sympathetic nervous system activity response to neurohumoral substances and endothelial factors myogenic adjustments at the cellular level, some mediated by ion channels and events at the cellular membrane and intercellular events mediated by receptors and mechanisms for signal transduction. As examples of some of these mechanisms, there are two major neural reflex arcs (Fig. 1). Baroreflexes are derived from high-pressure barorecep-tors in the aortic arch and carotid sinus and low-pressure cardiopulmonary baroreceptors in ventricles and atria. These receptors respond to stretch (high pressure) or... 

Finally, it has to be mentioned that LPA also has an intracellular target site, which is the nuclear transcription factor, peroxisome proliferator-activated receptor-y (PPARy). LPA competes for thiazolidinedione binding and activates PPARy-dependent gene transcription. Thereby, LPA induced neointima formation in a rat carotid artery model. 

Cardiovascular-peripheral vasodilation,decreased peripheral resistance, inhibition of baroreceptors (pressure receptors located in the aortic arch and carotid sinus that regulate blood pressure), orthostatic hypotension and fainting... 

Doxapram (Dopram) and caffeine (combination of caffeine and sodium benzoate) are two analeptics used in medicine Doxapram increases the depth of respirations by stimulating special receptors located in the carotid... 

They also seeded autologous vSMC and ECs obtained from ovine carotid arteries to study autologous tissue-engineering blood vessels in the descending aorta of juvenile sheep. They found that after three months implantation, grafts were fully patent, without dilatation, occlusion, or intimal thickening. A continuous luminal EC layer was formed. However, after six months ... 

The modern period in the history of stroke began in the 1960s when C. Miller Fisher described detailed clinical and pathological observations on the features of lacunar strokes, carotid artery disease, transient ischemic attacks, and intracerebral hemorrhage. His student Louis Caplan established one of the first stroke registry... 

Remonda L, Held O, Schroth G. Carotid artery stenosis, occlusion, and pseudoocclusion first-pass, gadolinium-enhanced, three-dimensional MR angiography— preliminary study. Radiology 1998 209 95-102 [see comment]. 

Lin W, Celik A, Derdeyn C, An H, Lee Y, Videen T, Qstergaard L, Powers WJ. Quantitative measurements of cerebral blood flow in patients with unilateral carotid artery occlusion a PET and MR study. J Magn Reson Imaging 2001 14 659-667. 

Phillips DA, Davis MA, Fisher M. Selective embolization and clot dissolution with tPA in the internal carotid artery circulation of the rabbit. AJNR Am J Neuroradiol. 1988 9 899-902. 

Georgiadis D, Lanczik O, Schwab S, Engelter S, Sztajzel R, Arnold M, Siebler M, Schwarz S, Lyrer P, Baumgartner RW. IV thrombolysis in patients with acute stroke due to spontaneous carotid dissection. Neurology. 2005 64 1612-1614. 

Internal Carotid Artery Occlusion Acute stroke due to a distal ICA T (T = terminus) occlusion carry a much worse prognosis than MCA occlusions. In a recent analysis of 24 consecutive patients (median NIHSS 19) presenting with T occlusions of the ICA who were treated by lAT using urokinase at an average of 237 minutes from symptom onset, only four patients (16.6%) had a favorable outcome at 3 months. Partial recanalization of the intracranial ICA was achieved in 15 (63%), of the MCA in 4 (17%), and of the ACA in 8 patients (33%). Complete recanalization did not occur. The presence of good leptomeningeal collaterals and age <60 years were the only predictors of a favorable clinical outcome. New treatment strategies, such as the combination of IV rt-PA and lAT, or the use of new mechanical devices may improve the outcome in these patients. 

A significant neurologic deficit expected to result in long-term disability, and attributable to large vessel occlusion (basilar, vertebral, internal carotid, or middle cerebral artery M1 or M2 branches). 

Acute ischemic stroke s3miptoms with onset or last known well, clearly defined. Treatment within 6 h of established, nonfluctuating deficits due to Anterior Circulation (carotid/MCA) stroke, between 6 and 8 h mechanical treatment (e.g.. Concentric Retriever) should be considered. The window of opportunity for treatment is less well defined in posterior circulation (vertebral/basilar) ischemia, and patients may have fluctuating, reversible ischemic symptoms over many hours or even days and stiU be appropriate candidates for therapy. 

Review of postcontrast CTA source images might provide a good estimate of whole-brain perfusion." If time allows, MR or CT perfusion maps are obtained to characterize more accurately the ischemic penumbra." Careful but expedited preprocedural analysis of the CTA, done in parallel with transport of the patient to the treatment area, may be extremely helpful in establishing the presence of anatomic variants (e.g., bovine aortic arch) or pathological states (e.g., vessel origin or carotid bifurcation disease) prior to the catheterization procedure. 

Arnold M, Nedeltchev K, Mattie HP, Loher TJ, Stepper F, Schroth G, Brekenfeld C, Sturzenegger M, Remonda L. Intra-arterial thrombolysis in 24 consecutive patients with internal carotid artery T occlusions. J Neurol Neurosurg Psychiatry 2003 74 739-742. 

Zaidat OO, Suarez Jl, Santillan C, Sunshine JL, Tarr RW, Paras VH, Selman WR, Landis DM. Response to intra-arterial and combined intravenous and intra-arterial thrombolytic therapy in patients with distal internal carotid artery occlusion. Stroke 2002 33 1821-1826. 

Jovin TG, Gupta R, Uchino K, Jungreis CA, Wechsler LR, Hammer MD, Tayal A, Horowitz MB. Emergent stenting of extracranial internal carotid artery occlusion in acute stroke has a high revascularization rate. Stroke 2005 36 2426-2430. 

Bellon RJ, Putman CM, Budzik RF, Pergolizzi RS, Reinking GF, Norbash AM. Rheolytic thrombectomy of the occluded internal carotid artery in the setting of acute ischemic stroke. Am J Neuroradiol 2001 22 526-530. 

The GP Ilb-IIIa complex inhibitor Tirofiban has been used as an adjunct to thrombolysis in a number of small case series reports." A small transcranial Doppler (TCD) study suggests that it reduces microembolization from unstable carotid plaque." In an open pilot smdy, Tirohban administered within 9 hours after stroke onset blocked the conversion of ischemic penumbra to mature infarction." A phase III study (SETIS) has started recruiting patients to investigate its efficacy versus aspirin within the 6-hour window. 

CEA involves exposure of the carotid bifurcation in the neck to a point along the internal carotid artery (ICA) beyond which the atherosclerotic plaque terminates. 

More recent reports conclude that early CEA after a nondisabling ischemic stroke can be performed with perioperative mortality and stroke rates comparable to those of delayed CEA. In a subgroup analysis by the North American Symptomatic Carotid Endarterectomy Trial (NASCET) investigators, 42 patients who underwent early CEA (<30 days after stroke) were compared with 58 patients who underwent delayed CEA (>30 days), and no overall difference was demonstrated in the perioperative stroke rate (4.8% vs. 5.2%). Another recent prospective randomized study of 86 patients showed no difference in either perioperative stroke (2% in both groups) or survival rates (mean 23 months follow-up) between patients randomized to early or delayed CEA. ... 

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