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Results for “Collateral Circulation”

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At least 1,171 records · Page 65Linked to original sources

PubMed1998

Splenorenal shunt blood flow by transit-time ultrasound as an index of collateral circulation in portal hypertensive rats.

The aim of this study was to develop a technique that could serve as an index of portosystemic shunt (PSS) blood flow in portal hypertensive rats whose main shunt is the splenorenal shunt (SRS). The main hemodynamic measurements performed were: SRS blood flow by the transit-time ultrasound (TTU) method, percentage of PSS, and regional blood flows by the microsphere method. We determined the accuracy and reproducibility of SRS blood flow measurements under baseline and pharmacological (octreotide) conditions. SRS blood flow was compared with other hemodynamic characteristics. Two models of portal hypertension were used: secondary biliary and dimethylnitrosamine cirrhosis. The SRS blood flow was correlated with mesenteric (r = .76; P < .001) and splenic (r = .67; P < .01) PSS percentages. The intra- and interobserver agreements for SRS blood flow were excellent: ric = .99 and ric = .98, respectively. SRS blood flow was six times higher in portal hypertensive rats (0.6 +/- 0.7 mL . min-1 . 100 g-1) than in sham rats (0.1 +/- 0.1 mL . min-1 . 100 g-1 [P < .01]). Octreotide significantly decreased SRS blood flow but not mesenteric or splenic PSS percentages. SRS is the main PSS in rats. The measurement of SRS blood flow by TTU is accurate and reproducible. This method can be used to identify new mechanisms in hemodynamic studies that differ from those identified by the measurement of the percentage of PSS by the microsphere method, especially in pharmacological studies.

Animals↗

PubMed1977

[Collateral circulations and new vessels in retinal branch vein occlusions. II. New vessels (author's transl)].

Two types of anastomotic new vessels develop after retinal branch vein occlusions. In a previous article (Arch. Ophtal. (Paris), 1977, 8-9, pp. 507-522) the useful collateral vessels were described in the re-establishment of a better circulation in the territory of the occluded vein. The second part discusses new vessels: they are dangerous and useless. Their pathogenesis poses the problem of the relationship between hypoxia, ischaemia, revascularisation and vasoproliferation. Their prevention and treatment calls for laser photocoagulation of the ischaemic territory.

Argon↗

PubMed2000

The pathophysiology of the collateral circulation (arteriogenesis).

Since the mid 1980s a new strategy is coming from bench to bedside termed angiogenesis. This process involves sprouting of capillaries and finally results in newly developed microvessels which belong to the capillary level. Importantly these newly formed capillary tubes lack vascular smooth muscle cells, they are not surrounded by mural cells and are fragile and prone to rupture. Therefore these networks remain susceptible to hypoxic regulation, fail to become remodelled and are unable to sustain proper circulation: they cannot adapt to changes in physiological demands of blood supply. Since atherosclerosis affects large conductance arteries, capillary sprouting from compromised vessels cannot provide an adequate supply of blood flow to the endangered tissue. However, the body provides a natural system of pre-existing collateral arteries, which may bypass sites of arterial occlusion. These vessels can dramatically increase their lumen by growth so as to provide enhanced perfusion to the jeopardized ischaemic regions. This process - termed arteriogenesis - finally results in fully functional and structurally normal arteries which can ameliorate the ensuing detrimental effects of vessel obstruction in many regions of the body. Hallmarks of arteriogenesis are increased levels of shear forces (rather than ischaemia), the invasion of circulating monocytes (and their pluripotent precursors), and the substrates of arteriogenesis are pre-existing collateral arterioles.

Angiogenesis Inducing Agents↗

PubMed1994

[Per-rectal scintigraphy of the portal system with pertechnetate TC-99M: effect of propranolol on portosystemic collateral circulation in patients with cirrhosis. Part II].

Propranolol can reduce portal hypertension, therefore is recommended in prevention of variceal bleeding in patients with liver cirrhosis. However, in certain patients with cirrhosis portal hypotensive effect of propranolol cannot be obtained, and the reason of this finding is unknown. In 28 patients with cirrhosis the effect of seven days administration of propranolol on collateral blood flow from inferior mesenteric vein was examined by means of per-rectal portal scintigraphy. Portosystemic shunt index was significantly reduced by propranolol by 17.4 +/- 4.8%. This reduction was observed in cirrhotics classified to A and B, but not C Child-Pugh. These data suggest that propranolol increases vascular resistance in portosystemic circulation which depends on severity of liver failure. This mechanism opposes reduction of portal pressure.

Adult↗

PubMed1990

[Collateral circulation after division of the common hepatic artery--clinical study concerning Appleby's operation].

The alteration of the blood flow of the proper hepatic artery (PHA) on occlusion of the common hepatic artery (CHA) was studied intraoperatively using an electromagnetic flowmeter for 18 cases of malignant gastric tumor. PHA blood flow was 280 +/- 225 ml/min before CHA occlusion, and after the occlusion it was 170 +/- 132 ml/min, or 64 +/- 15% of the pre-occlusion flow (n = 16). The pulsation of PHA after CHA occlusion was palpable in all cases, and there were no complications due to ischemia in 17 cases which underwent Appleby's operation. These results suggested that there was fairly good blood flow in PHA maintained by collaterals after CHA occlusion and that, clear pulsation of PHA could be regarded as evidence of sufficient blood flow. Tissue blood flow (TBF) measurement for the liver and gall-bladder by H2 gas clearance method was also done in several cases of Appleby's operation and of other abdominal operations. TBF of the gallbladder was significantly lower in cases of Appleby's operation on the day of operation (p less than 0.02), but the difference between the two operation groups was not recognized 5 days after surgery, suggesting rather quick recovery of circulation. As to hepatic TBF, significant decrease following Appleby's operation could not be proved.

Adult↗

PubMed2006

Carotid artery occlusion and collateral circulation in C57Black/6J mice detected by synchrotron radiation microangiography.

Using monochromatic synchrotron radiation, we performed microangiography in C57BL/6J mice and investigated their vasculature after unilateral and bilateral carotid artery occlusion. Bilateral occlusion of the carotid artery was made by a ligation of the left common carotid artery followed by a ligation of the right internal carotid artery (ICA) two days later (n=12). Five days after the second surgery, angiography was performed. Unilateral occlusion was made by clipping the right ICA and then angiography was performed immediately (n=5). The control mice did not undergo any occlusion (n=5). We removed the brain of the bilateral occlusion mice after angiography and examined the infarction area. The cerebral microvessels in all animals were clearly visualized. In the control mice, the posterior communicating artery (Pcom) was not visualized. In the unilateral occlusion mice, the anastomosis of the pterygopalatine artery (PPA) and the external carotid artery (ECA) were recognized. The PPA is thus considered to play a role in the collateral vessel between the ICA and the ECA. The Pcom was not visualized. In the bilateral occlusion mice, the Pcom was observed either unilaterally (n=5) or bilaterally (n=5). The Pcom supplied blood flow to the anterior circulation from the vertebrobasilar arteries. The bilateral occlusion mice that had at least one visualized Pcom did not have any infarction. We could successfully visualize the cerebral vasculature of normal mice and carotid artery occluded mice in an in vivo study. Microangiography can demonstrate the development of vasculature and the blood flow dynamics in mice.

Angiography↗

PubMed2001

Menorrhagia and adenomyosis in a patient with hyperhomocysteinemia, recurrent pelvic vein thromboses and extensive uterine collateral circulation treatment by supracervical hysterectomy.

A 37-year-old patient had recurring thromboses, occlusion of the left femoral vein with hereditary hyperhomocysteinemia, hypermenorrhea and anaemia. Conservative therapy with endometrium ablation and gestagene failed. A supracervical hysterectomy was done to preserve the presacral and left lateral, dorsal and caudal collaterals beside the uterus, and prevent a postoperative congestion, especially of the left leg.

Adult↗

PubMed1996

Evaluation of surgically formed collateral circulation in moyamoya disease with 3D-CT angiography: comparison with MR angiography and X-ray angiography.

Three patients with moyamoya disease who had undergone bypass surgery at which bilateral encephaloduro-arterio-synangiosis (EDAS) anastomoses were created were studied with three-dimensional spiral CT angiography (3D-CTA). In one patient, magnetic resonance angiography (MRA) clearly visualized the bilateral EDAS, and 3D-CTA also visualized these anastomoses in detail with extreme clarity. In the other two patients, MRA did not clearly demonstrate the right EDAS anastomosis, but 3D-CTA visualized both side surgical collaterals clearly. External carotid angiography confirmed these findings. 3D-CTA might have great value in the evaluation of surgical bypass patency and, in following the disease progression.

Anastomosis, Surgical↗

PubMed1966