Home About us Contact
|
Home About us Contact | ||
|
|
||
Collateral Vessels (collateral + vessel)
Selected AbstractsLong-term study of vascular perfusion effects following arteriovenous sheathotomy for branch retinal vein occlusionACTA OPHTHALMOLOGICA, Issue 3 2010Mahiul M. K. Muqit Abstract. Purpose:, To evaluate the perfusion effects and long-term visual outcome of pars plana vitrectomy (PPV) combined with arteriovenous sheathotomy (AVS) with or without triamcinolone for nonischaemic branch retinal vein occlusion (NI-BRVO). Methods:, Prospective, interventional case series of eight patients with NI-BRVO and haemorrhagic macular oedema. Patients underwent PPV and AVS (n = 5), or PPV, AVS and intravitreal triamcinolone (IVT, n = 3). A masked grading technique assessed fundus photographs and fluorescein angiography (FFA) following surgery. Scanning laser ophthalmoscopy/optical coherence tomography (SLO/OCT) evaluated macular oedema and outer retinal architecture. Main outcomes examined included visual acuity (VA), retinal reperfusion, collateral vessel regression, vascular dilatation, cystoid macular oedema (CMO), and ocular neovascularization. Results:, Seven of eight patients underwent uncomplicated surgery, with increased intraretinal perfusion and reduced engorgement of distal retinal veins. The mean pre-logMAR VA was 0.8 (SD 0.17) and did not improve significantly after surgery (post-logMAR 0.6, SD 0.38; p = 0.11, paired t -test). SLO/OCT showed persistent CMO in four patients, and subfoveal thinning of the photoreceptor layer. Collateral vessels disappeared at the blockage site post-AVS in 7/8 eyes, and this was associated with improved retinal perfusion. Six of eight patients developed epiretinal membrane. No patients developed ocular neovascularization. The average follow-up was 34.5 months. Conclusions:, PPV with AVS is a safe procedure, and adjunctive IVT had no additional effects on vascular perfusion. Successful decompressive surgery was followed by disappearance of collateral vessels at the BRVO blockage site and was a clinical marker for intravascular reperfusion. Long-term epiretinal gliosis and subfoveal photoreceptor atrophy limited functional and visual recovery. [source] Simvastatin effects on portal-systemic collaterals of portal hypertensive ratsJOURNAL OF GASTROENTEROLOGY AND HEPATOLOGY, Issue 8 2010Hui-Chun Huang Abstract Background and Aim:, Portal-systemic collateral vascular resistance and vasoconstrictor responsiveness are crucial in portal hypertension and variceal bleeding control. Statins enhance vasodilators production, but their influence on collaterals is unknown. This study aimed to survey the effect of simvastatin on collaterals. Methods:, Partially portal vein-ligated rats received oral simvastatin (20 mg/kg/day) or distilled water from ,2 to +7 day of ligation. After hemodynamic measurements on the eighth postoperative day, baseline perfusion pressure (i.e. an index of collateral vascular resistance) and arginine vasopressin (AVP, 0.1 nM,0.1 µM) responsiveness were evaluated with an in situ perfusion model for collateral vascular beds. RT-PCR of endothelial NO synthase (eNOS), inducible NOS (iNOS), cyclooxygenase-1 (COX-1), COX-2, thromboxane A2 synthase (TXA2 -S) and prostacyclin synthase genes was performed in parallel groups for splenorenal shunt (SRS), the most prominent intra-abdominal collateral vessel. To determine the acute effects of simvastatin, collateral AVP response was assessed with vehicle or simvastatin. SRS RT-PCR of eNOS, iNOS, COX-1, COX-2 and TXA2 -S, and measurements of perfusate nitrite/nitrate, 6-keto-PGF1, and TXB2 levels were performed in parallel groups without AVP. Results:, Acute simvastatin administration enhanced SRS eNOS expression and elevated perfusate nitrite/nitrate and 6-keto-PGF1, concentrations. Chronic simvastatin treatment reduced baseline collateral vascular resistance and portal pressure and enhanced SRS eNOS, COX-2 and TXA2 -S mRNA expression. Neither acute nor chronic simvastatin administration influenced collateral AVP responsiveness. Conclusion:, Simvastatin reduces portal-systemic collateral vascular resistance and portal pressure in portal hypertensive rats. This may be related to the enhanced portal-systemic collateral vascular NO and prostacyclin activities. [source] Treatment of chronic total occlusion by retrograde passage of stents through an epicardial collateral vessel,CATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 3 2008Darpan Bansal MD Abstract Chronic total occlusion (CTO) may occur in as many as 30,40% of patients with coronary artery disease. Retrograde revascularization through a collateral channel has been described earlier. We report the first case of retrograde passage of a stent through an epicardial collateral to revascularize a right coronary artery CTO. © 2008 Wiley-Liss, Inc. [source] CHARACTERISTIC INTRADUCTAL ULTRASONOGRAPHIC FEATURES OF PORTAL BILIOPATHYDIGESTIVE ENDOSCOPY, Issue 4 2008Tsukasa Ikeura The term ,portal biliopathy' is used to describe cholangiographic abnormalities seen in patients with extrahepatic portal vein obstruction. Portal biliopathy is mainly composed of extrinsic compression of the bile duct caused by enlarged venous collaterals. Herein we report a case of asymptomatic portal biliopathy caused by idiopathic extrahepatic portal vein obstruction. In the present case, intraductal ultrasonography showed normal anatomic layers of the distal common bile duct wall, surrounded by numerous tubular structures which were suspected to be collateral vessels. We suggest that intraductal ultrasonography may be a helpful imaging procedure for detection of this pathological condition. [source] Stress-Induced Wall Motion Abnormalities with Low-Dose Dobutamine Infusion Indicate the Presence of Severe Disease and Vulnerable MyocardiumECHOCARDIOGRAPHY, Issue 7 2007Stephen G. Sawada M.D. Background: Patients with left ventricular (LV) systolic dysfunction due to coronary artery disease (CAD) may develop stress-induced wall motion abnormalities (SWMA) with low-dose (10 ,g/kg/min) dobutamine infusion. The clinical significance of low-dose SWMA is unknown. Objective: We investigated the clinical, hemodynamic and angiographic correlates of low-dose SWMA in patients with chronic ischemic LV systolic dysfunction. Methods: Seventy patients with chronic ischemic LV systolic dysfunction who had dobutamine stress echocardiography were studied. Clinical, hemodynamic, and angiographic parameters at rest and low-dose were compared between 38 patients (mean ejection fraction (EF) of 30 ± 8%) with low-dose SWMA and 32 patients (EF 30 ± 11%) without low-dose SWMA. Results: Multivariate analysis showed that the number of coronary territories with severe disease (stenosis ,70%)(P = 0.001, RR = 6.3) was an independent predictor of low-dose SWMA. An increasing number of collateral vessels protected patients from low-dose SWMA (P = 0.011, RR = 0.25). A higher resting heart rate was a negative predictor of low-dose SWMA (P = 0.015, RR = 0.92) but no other hemodynamic variables were predictors. In the patients with low-dose SMA, regions with low-dose SWMA were more likely to be supplied by vessels with severe disease than regions without low-dose SWMA (92% vs 58%, P < 0.001). Conclusion: In patients with ischemic LV systolic dysfunction, the extent of severe disease and a lower numbers of collaterals predict the occurrence of low-dose SWMA. Low-dose SWMA is a highly specific marker for severe disease. [source] Cardiovascular risk factors and collateral artery formationEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 12 2009D. De Groot Abstract Arterial lumen narrowing and vascular occlusion is the actual cause of morbidity and mortality in atherosclerotic disease. Collateral artery formation (arteriogenesis) refers to an active remodelling of non-functional vascular anastomoses to functional collateral arteries, capable to bypass the site of obstruction and preserve the tissue that is jeopardized by ischaemia. Hemodynamic forces such as shear stress and wall stress play a pivotal role in collateral artery formation, accompanied by the expression of various cytokines and invasion of circulating leucocytes. Arteriogenesis hence represents an important compensatory mechanism for atherosclerotic vessel occlusion. As arteriogenesis mostly occurs when lumen narrowing by atherosclerotic plaques takes place, presence of cardiovascular risk factors (e.g. hypertension, hypercholesterolaemia and diabetes) is highly likely. Risk factors for atherosclerotic disease affect collateral artery growth directly and indirectly by altering hemodynamic forces or influencing cellular function and proliferation. Adequate collateralization varies significantly among atherosclerotic patients, some profit from the presence of extensive collateral networks, whereas others do not. Cardiovascular risk factors could increase the risk of adverse cardiovascular events in certain patients because of the reduced protection through an alternative vascular network. Likewise, drugs primarily thought to control cardiovascular risk factors might contribute or counteract collateral artery growth. This review summarizes current knowledge on the influence of cardiovascular risk factors and the effects of cardiovascular medication on the development of collateral vessels in experimental and clinical studies. [source] Effects of endothelin-1 on portal-systemic collaterals of common bile duct-ligated cirrhotic ratsEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 4 2004C.-C. Chan Abstract Background/Aims, Endothelin-1 (ET-1) may induce intrahepatic vasoconstriction and consequently increase portal pressure. Endothelin-1 has been shown to exert a direct vasoconstrictive effect on the collateral vessels in partially portal vein-ligated rats with a high degree of portal-systemic shunting. This study investigated the collateral vascular responses to ET-1, the receptors in mediation and the regulation of ET-1 action by nitric oxide and prostaglandin in cirrhotic rats with a relatively low degree of portal-systemic shunting. Methods, The portal-systemic collaterals of common bile duct-ligated (BDL) cirrhotic rats were tested by in situ perfusion. The concentration-response curves of collaterals to graded concentrations of ET-1 (10,10,10,7 m) with or without BQ-123 (ETA receptor antagonist, 2 × 10,6 m), BQ-788 (ETB receptor antagonist, 10,7 m) or both were recorded. In addition, the collateral responses to ET-1 with preincubation of N, -nitro-L-arginine (NNA, 10,4 M), indomethacin (INDO, 10,5 M) or in combination were assessed. Results, Endothelin-1 significantly increased the perfusion pressures of portal-systemic collaterals. The ET-1-induced constrictive effects were inhibited by BQ-123 or BQ-123 plus BQ-788 but not by BQ-788 alone. The inhibitory effect was greater in the combination group. Pretreatment of NNA or NNA plus INDO equivalently enhanced the response of ET-1 while pretreatment of INDO alone exerted no effect. Conclusion, Endothelin-1 has a direct vasoconstrictive effect on the collaterals of BDL cirrhotic rats, mainly mediated by ETA receptor. Endogenous nitric oxide may play an important role in modulating the effects of ET-1 in the portal-systemic collaterals of BDL cirrhotic rats. [source] Unusual hepatic-portal-systemic shunting demonstrated by Doppler sonography in children with congenital hepatic vein ostial occlusionJOURNAL OF CLINICAL ULTRASOUND, Issue 4 2004Maha Barakat MD Abstract Purpose This report describes unusual changes in the hepatic vasculature in 3 children presenting with upper gastrointestinal hemorrhage. Methods The study included 3 children (ages 5,8 years) who presented with hematemesis. All had mild hepatosplenomegaly and normal liver function. Esophageal varices were demonstrated in all on upper endoscopy. Color and spectral Doppler sonography was performed to assess the hepatic vasculature, including the hepatic veins (HVs), portal vein (PV), hepatic artery (HA), and inferior vena cava (IVC). Results The HVs were all patent but with ostial occlusion at the point of their communication with the IVC. Complete flow reversal was shown inside the HVs, with blood draining into collateral vessels at the liver surface and paraumbilical vein. In one patient, the paraumbilical vein could be traced to its communication with the right external iliac vein. In all children, the direction of flow in the PV, HA, and IVC was normal. After endoscopic sclerotherapy, all children were shown to be in good general condition and to have normal liver function for a follow-up period of 15,36 months. Conclusions Ostial occlusion of the HV is a rare cause of hepatic outflow obstruction in children. Doppler sonography is a valuable, noninvasive imaging technique for evaluation of the hepatic vasculature and the accompaning shunting pathways in such cases. © 2004 Wiley Periodicals, Inc. J Clin Ultrasound 32:172,178, 2004; Published online in Wiley InterScience (www. interscience.wiley.com). DOI: 10.1002/jcu.20019 [source] Multidetector CT portal venography in evaluation of portosystemic collateral vesselsJOURNAL OF MEDICAL IMAGING AND RADIATION ONCOLOGY, Issue 1 2008A Agarwal Summary This essay shows the usefulness of multidetector CT angiography for evaluation of the splenoportal venous system, which is essential in the management of patients with portal hypertension and its complications, such as portal vein thrombosis. By providing scanning with reconstruction of thin axial source images and reformatting into thicker multiplanar reformats, multidetector CT can help to determine the extent and location of portosystemic collateral vessels in patients with portal hypertension and is probably the optimal imaging technique in this setting. [source] Membranous obstruction of the inferior vena cava and its causal relation to hepatocellular carcinomaLIVER INTERNATIONAL, Issue 1 2006M. C. Kew Abstract: Although rare in most countries, membranous obstruction of the inferior vena cava (MOIVC) occurs more frequently in Nepal, South Africa, Japan, India, China, and Korea. The occlusive lesion always occurs at approximately the level of the diaphragm. It commonly takes the form of a membrane, but may be a fibrotic occlusion of variable length. Controversy exists as to whether MOIVC is a developmental abnormality or a result of organization of a thrombus in the hepatic portion of the inferior vena cava. The outstanding physical sign associated with MOIVC are large truncal collateral vessels with a cephalad flow. A dilated vena azygous is seen on chest radiography. Definitive diagnosis is made by contrast inferior vena cavography. The long-standing obstruction to hepatic venous flow causes severe centrolobular fibrosis and predisposes to the development of hepatocellular carcinoma (HCC). Percutaneous balloon angioplasty, transatrial membranotomy, or more complex vena caval and portal decompression surgery should be performed to prevent these complications. HCC occurs in more than 40% of South African Black and Japanese patients with MOIVC, but less often in other populations. It is thought to result from the tumour-promoting effect of continuous hepatocyte necrosis, although the associated environmental risk factors have not been identified. [source] Magnetic resonance angiography of collateral vessels in a murine femoral artery ligation modelNMR IN BIOMEDICINE, Issue 1 2004Shawn Wagner Abstract The in vivo detection of growing collateral vessels following arterial occlusion is difficult in small animals. We have addressed the feasibility of performing high resolution time-of-flight angiograms to monitor the growth of collateral vessels after femoral artery occlusion in mice. We will also present a low-pass quadrature birdcage coil construction with a sufficient signal-to-noise ratio to produce high resolution. After a 4-month recovery period a C57BL/6 mouse with a surgical occlusion of the right femoral artery was used to assess the image quality and time requirements to produce magnetic resonance angiograms sufficient to assess collateral artery development using a two-dimensional gradient echo sequence. At a resolution of 100,×,100,×,100,,m and a matrix size of 256,×,128,×,256 for a 2.56,cm isometric volume, three scans were performed with one, two and four repetitions resulting in signal-to-noise ratios for the femoral artery proximal to the ligation site of 58, 126 and 194, respectively. Five C57BL/6 mice were additionally measured 4 weeks after occlusion using two repetitions and the visual collateral vessels were assessed for number and location: 2.0,±,1.2 in quadriceps muscle, 0.6,±,0.5 in adductor (deep adductor vessel), 0.0,±,0.0 in adductor (surface adductor vessels). The results showed a significant difference, two-sided t -test, p,<,0.05, in number of vessels in all the locations. We have shown that this method can be utilized to elucidate the contribution of collateral vessels to arterial flow. Copyright © 2004 John Wiley & Sons, Ltd. [source] ,-Adrenergic and neuropeptide Y Y1 receptor control of collateral circuit conductance: influence of exercise trainingTHE JOURNAL OF PHYSIOLOGY, Issue 24 2008Jessica C. Taylor This study evaluated the role of ,-adrenergic receptor- and neuropeptide Y (NPY) Y1 receptor-mediated vasoconstriction in the collateral circuit of the hind limb. Animals were evaluated either the same day (Acute) or 3 weeks following occlusion of the femoral artery; the 3-week animals were in turn limited to cage activity (Sed) or given daily exercise (Trained). Collateral-dependent blood flows (BFs) were measured during exercise with microspheres before and after ,-receptor inhibition (phentolamine) and then NPY Y1 receptor inhibition (BIBP 3226) at the same running speed. Blood pressures (BPs) were measured above (caudal artery) and below (distal femoral artery) the collateral circuit. Arterial BPs were reduced by ,-inhibition (50,60 mmHg) to ,75 mmHg, but not further by NPY Y1 receptor inhibition. Effective experimental sympatholysis was verified by 50,100% increases (P < 0.001) in conductance of active muscles not affected by femoral occlusion with receptor inhibition. In the absence of receptor inhibition, vascular conductance of the collateral circuit was minimal in the Acute group (0.13 ± 0.02), increased over time in the Sed group (0.41 ± 0.03; P < 0.001), and increased further in the Trained group (0.53 ± 0.03; P < 0.02). Combined receptor inhibition increased collateral circuit conductances (P < 0.005), most in the Acute group (116 ± 37%; P < 0.02), as compared to the Sed (41 ± 6.6%; P < 0.001) and Trained (31 ± 5.6%; P < 0.001) groups. Thus, while the sympathetic influence of the collateral circuit remained in the Sed and Trained animals, it became less influential with time post-occlusion. Collateral conductances were collectively greater (P < 0.01) in the Trained as compared to Sed group, irrespective of the presence or absence of receptor inhibition. Conductances of the active ischaemic calf muscle, with combined receptor inhibition, were suboptimal in the Acute group, but increased in Sed and Trained animals to exceptionally high values (e.g. red fibre section of the gastrocnemius: ,7 ml min,1 (100 g),1 mmHg,1). Thus, occlusion of the femoral artery promulgated vascular adaptations, even in vessels that are not part of the collateral circuit. The presence of active sympathetic control of the collateral circuit, even with exercise training, raises the potential for reductions in collateral BF below that possible by the structure of the collateral circuit. However, even with release of this sympathetic vasoconstriction, conductance of the collateral circuit was significantly greater with exercise training, probably due to the network of structurally larger collateral vessels. [source] Percutaneous occlusion of a pulmonary aneurysm causing hemoptysis in a patient with pulmonary atresia and aortopulmonary collateralsCATHETERIZATION AND CARDIOVASCULAR INTERVENTIONS, Issue 2 2005Gordon E. Pate Abstract A 28-year-old male was referred for cardiac catheterization because of recurrent severe hemoptysis necessitating resuscitation and subsequently preventing weaning from ventilation. He had a history of pulmonary atresia, ventricular septal defect, overriding aorta with right-sided aortic arch diagnosed at birth. Eisenmenger's syndrome ensued and he was not felt to be suitable for corrective cardiac surgery. He had multiple major aortopulmonary collateral vessels to both lungs with a large aneurysm in an artery to the right lower lobe, which was suspected to be the source of his bleeding. Occlusion of this aneurysm was achieved percutaneously using an Amplatzer septal occluder device. He had no further bleeding and was successfully weaned from ventilation. Six months later, he has recovered to his functional baseline and has not had any further episodes of hemoptysis. © 2005 Wiley-Liss, Inc. [source] Long-term study of vascular perfusion effects following arteriovenous sheathotomy for branch retinal vein occlusionACTA OPHTHALMOLOGICA, Issue 3 2010Mahiul M. K. Muqit Abstract. Purpose:, To evaluate the perfusion effects and long-term visual outcome of pars plana vitrectomy (PPV) combined with arteriovenous sheathotomy (AVS) with or without triamcinolone for nonischaemic branch retinal vein occlusion (NI-BRVO). Methods:, Prospective, interventional case series of eight patients with NI-BRVO and haemorrhagic macular oedema. Patients underwent PPV and AVS (n = 5), or PPV, AVS and intravitreal triamcinolone (IVT, n = 3). A masked grading technique assessed fundus photographs and fluorescein angiography (FFA) following surgery. Scanning laser ophthalmoscopy/optical coherence tomography (SLO/OCT) evaluated macular oedema and outer retinal architecture. Main outcomes examined included visual acuity (VA), retinal reperfusion, collateral vessel regression, vascular dilatation, cystoid macular oedema (CMO), and ocular neovascularization. Results:, Seven of eight patients underwent uncomplicated surgery, with increased intraretinal perfusion and reduced engorgement of distal retinal veins. The mean pre-logMAR VA was 0.8 (SD 0.17) and did not improve significantly after surgery (post-logMAR 0.6, SD 0.38; p = 0.11, paired t -test). SLO/OCT showed persistent CMO in four patients, and subfoveal thinning of the photoreceptor layer. Collateral vessels disappeared at the blockage site post-AVS in 7/8 eyes, and this was associated with improved retinal perfusion. Six of eight patients developed epiretinal membrane. No patients developed ocular neovascularization. The average follow-up was 34.5 months. Conclusions:, PPV with AVS is a safe procedure, and adjunctive IVT had no additional effects on vascular perfusion. Successful decompressive surgery was followed by disappearance of collateral vessels at the BRVO blockage site and was a clinical marker for intravascular reperfusion. Long-term epiretinal gliosis and subfoveal photoreceptor atrophy limited functional and visual recovery. [source] The clinical anatomy of the coronary collateral circulationCLINICAL ANATOMY, Issue 1 2009Marios Loukas Abstract Although the structure and function of the coronary vasculature has been exhaustively studied, it still holds significant elements of mystery for the researcher and clinician. This is particularly true regarding the structure and function of the human collateral coronary circulation. Controversy still exists concerning the pathways of collateral vessels as well as their function. Controversies also exist relative to the methods used to delineate the pathways, these being additionally compounded by the lack of standardization of the studies and measurements. In this review, we summarize our current knowledge of this functionally significant vascular network. Clin. Anat. 22:146,160, 2009. © 2008 Wiley-Liss, Inc. [source] | |||||||||||||