Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “VESSELS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,153 records · Page 64Linked to original sources
PubMed2006

Spatio-temporal VEGF and PDGF delivery patterns blood vessel formation and maturation.

PURPOSE: Biological mechanisms of tissue regeneration are often complex, involving the tightly coordinated spatial and temporal presentation of multiple factors. We investigated whether spatially compartmentalized and sequential delivery of factors can be used to pattern new blood vessel formation. MATERIALS AND METHODS: A porous bi-layered poly(lactide-co-glycolide) (PLG) scaffold system was used to locally present vascular endothelial growth factor (VEGF) alone in one spatial region, and sequentially deliver VEGF and platelet-derived growth factor (PDGF) in an adjacent region. Scaffolds were implanted in severely ischemic hindlimbs of SCID mice for 2 and 6 weeks, and new vessel formation was quantified within the scaffolds. RESULTS: In the compartment delivering a high dose of VEGF alone, a high density of small, immature blood vessels was observed at 2 weeks. Sequential delivery of VEGF and PDGF led to a slightly lower blood vessel density, but vessel size and maturity were significantly enhanced. Results were similar at 6 weeks, with continued remodeling of vessels in the VEGF and PDGF layer towards increased size and maturation. CONCLUSIONS: Spatially localizing and temporally controlling growth factor presentation for angiogenesis can create spatially organized tissues.

Animals↗
PubMed1985

Statistical considerations on the precision of assessing blood vessel diameter in cine coronary angiography.

Problems related to the precision of computerized measurement and analysis of blood vessel diameter from digitized cineangiographic vessel images are described, and shortcomings of the conventional definition of percent stenosis are discussed. Formulae for the precision of percent stenosis, for the minimum significant measurable changes in blood vessel diameter, for the necessary scanning resolution, and for absolute vessel diameter measurement are provided. A Monte Carlo procedure-based technique for assessing the effect of radiographic noise on the location of vessel boundaries within the transverse densitometric image profile is presented and applied to contrast-filled cylindrical phantoms. The results demonstrate the feasibility for achieving subpixel resolution in computerized detection of vessel edges and diameter measurement.

Cineangiography↗
PubMed1986

Atherosclerotic involvement of coronary branch vessels.

The atherosclerotic involvement of coronary branch vessels (first diagonal, first septal, posterior descending, left and right marginals, conus and the vessels supplying the conduction system) was investigated in 450 apparently healthy subjects aged 11-55 years who died of accidental causes. In subjects 35-55 years old, 1 out of every 3 persons with atherosclerotic plaques in the major coronary arteries also had atherosclerotic plaques in coronary branch vessels; the respective relation for fatty streaks was 1 out of every 12 subjects, for intimal necrotic areas 1 out of every 7 subjects and for incorporated microthrombi 1 out of every 9 subjects. One out of every 3 subjects 51-55 years old had more than 50% lumen reduction in the undistended major coronary arteries, compared to 1 out of every 6 subjects in undistended coronary branch vessels. A small subgroup (8.2%) showed more severe stenotic lesions in coronary branch vessels than in coronary major arteries. The atherosclerotic plaques of coronary branch vessels appeared as 'underdeveloped', lacking a thick fibrohyaline cap, a large detritus cavity, abundant lipid deposition, cholesterol crystals, basal vascularization, intraplaque hemorrhage, ulceration, calcification, occlusive thrombosis. On the other hand the stenotic character of these plaques was often severe (more than 75% lumen reduction). The questionable value of the estimation of the ischemic significance of a coronary stenosis in the absence of available data on the development of a compensatory collateral circulation is discussed.

Adolescent↗
PubMed1995

Neovascularization of the testicle through spermatic vessels by omental pedicle flap: a new experimental model.

The aim of this experimental study in rats was to consider the supplementary role of an omental pedicle flap on the neovascularization of the testicle through the spermatic vessels, for which a Fowler-Stephens procedure had been planned. To compare results, 12 animals had only the spermatic vessels ligated, without an additional procedure (Fowler-Stephens procedure [FS group]), and 12 others had omentopexy of the spermatic vessels of the left testes, with ligation of the vessels 4 weeks later (Fowler-Stephens procedure plus omentopexy [FSO group]). In the sham group (n = 8), only omentopexy of the left spermatic vessels was performed. Six rats served as controls. In each rat, both testes were evaluated by color Doppler ultrasonography to assess capsular and intratesticular blood flow, followed by orchiectomy to determine testicular weights, testicular biopsy scores, and mean seminiferous tubule diameters. Data were analyzed statistically. According to the color Doppler ultrasonography, the testicular blood flow in the FSO group was better than that of the FS group, but was less sufficient than that of the sham and control groups. The testicular weights and biopsy scores for the FSO group were statistically greater than those of the FS group, and less than those of the sham and control groups. There was no significant difference in the mean seminiferous tubule diameters of the FSO and FS groups. The contralateral tests of the four groups did not differ significantly for any parameter. In light of the data available, it is suggested that the omental pedicle flap neovascularizes the testicle through spermatic vessels. Given the high incidence of testicular atrophy associated with Fowler-Stephens orchiopexies, it might be beneficial to perform laparoscopic orchiopexy of testicles neovascularized with omental pedicle flaps as the first-stage procedure.

Animals↗
PubMed1991

A quantitative study of the coincidence of blood vessels and A4 protein deposits in Alzheimer's disease.

The spatial relationship between A4 protein deposits and blood vessels in the brains of 6 elderly cases of Alzheimer's disease has been investigated. Sections were taken from medial temporal cortex and were double immunostained for A4 protein and type IV collagen, the latter being employed as a marker of blood vessels. By comparing the observed area of vessel overlying A4 deposit with that predicted from the product of A4 deposit and blood vessel area fractions it is shown that, contrary to expectations, the likelihood of a vessel co-inciding with an A4 deposit is less than would be expected by chance. It would therefore appear that the previously described positive association between A4 deposits and blood vessels reflects the abundance of A4 and the high vascularity of the cortex rather than any specific correlation between the two features.

Aged↗
PubMed1996

Relationships between beta-amyloid (A beta) deposits and blood vessels in patients with sporadic and familial Alzheimer's disease.

The density of diffuse, primitive and classic beta-amyloid (A beta) deposits was studied in relation to the incidence of blood vessels in the superior frontal gyrus of nine cases of sporadic Alzheimer's disease (SAD), two cases of familial Alzheimer's disease (FAD) with amyloid precursor protein (APP) mutations (APP717, Val --> Ile), and eight cases of FAD not linked to chromosomes 21, 14 or 1. Stepwise multiple regression was used to determine for each patient whether variations in the density of A beta deposits along the cortex were significantly correlated with the incidence of blood vessels. In the majority of FAD and SAD cases, the density of the diffuse and primitive type A beta deposits was not related to blood vessels. However, the incidence of the larger diameter (> 10 microns) blood vessels was positively correlated with the density of the classic A beta deposits in eight (89%) SAD and two (20%) FAD cases. The data suggest that the densities of vessels and deposits were not significantly correlated between cases but only within cases, suggesting a strictly local effect. In addition, the spatial association between classic A beta deposits and blood vessels may be more apparent in SAD compared with FAD cases.

Aged↗
PubMed1994

Relation between changes in blood flow of the contralateral coronary artery and the angiographic extent and function of recruitable collateral vessels arising from this artery during balloon coronary occlusion.

OBJECTIVES: The purpose of this study was to investigate changes in the magnitude of blood flow through the contralateral coronary artery in relation to the development of recruitable collateral vessels arising from this artery to supply a balloon-occluded coronary vessel. BACKGROUND: Recruitable collateral vessels have been shown to emerge suddenly to supply an occluded coronary artery, but their physiologic effect cannot always be predicted angiographically. METHODS: Twenty-four patients were studied during four successive balloon dilations for single left anterior descending coronary artery stenosis. Before and during each balloon occlusion, blood flow in the proximal right coronary artery was measured by intracoronary Doppler flow velocimetry and quantitative coronary angiography. Estimates of chest pain and ST segment elevation were also obtained. RESULTS: Fourteen patients developed angiographically visible recruitable collateral vessels (high grade in 6 [group III], low grade in 8 [group II]), whereas 10 patients (group I) did not. During the four successive balloon occlusions, the right coronary artery flow showed transient reproducible increases in group III (first occlusion 66.4 +/- 36.8%, fourth occlusion 64 +/- 23.9%, all p = 0.036), progressive increases in group II (from first occlusion 17.9 +/- 26.6% [p = 0.08] to fourth occlusion 60.4 +/- 35.9% [p = 0.014]) and no significant changes in group I. Between the first and the fourth occlusion, the severity of chest pain and the magnitude of ST segment elevation declined significantly in group II but did not change in groups I and III. CONCLUSIONS: During balloon coronary artery occlusion, the transient appearance of recruitable collateral vessels is associated with a transient increase in blood flow through the collateral donor artery. This increase in coronary flow appears to reflect collateral function better than the angiographic assessment, especially in patients with poor collateral vessel recruitment.

Adult↗
PubMed2004

Randomized comparison of direct stenting with predilatation followed by stenting on vessel trauma and restenosis.

BACKGROUND: Direct stenting may reduce trauma to the vessel wall, thereby having a positive impact on acute and long-term results. This study evaluated acute vessel trauma and acute and follow-up angiographic and intravascular ultrasound (IVUS) results after direct stenting in comparison to conventional stenting. METHODS: Two hundred forty-nine patients were randomly assigned to direct stenting (n = 124) or stenting after predilatation (n = 125) and were followed up by angiography at 6 +/- 2 months. Intracoronary serum endothelin (ET-1) levels were determined distal to the lesion before and after coronary intervention to define vessel trauma, and IVUS was performed before and after intervention and at follow-up to determine induced changes in vessel morphology and intimal hyperplasia in a subgroup of 40 patients. RESULTS: Feasibility of direct stenting was 91%, with 9% requiring crossover to predilatation. There were no differences between the 2 groups in immediate clinical, angiographic, and intravascular ultrasound results. Intracoronary ET-1 levels increased significantly after intervention, without differences between the 2 groups (increase in ET-1 level, 0.79 +/- 1.06 vs 0.96 +/- 1.22 fmol/L, P =.206). At 6-month follow-up, angiographic late loss (0.76 +/- 0.86 vs 0.69 +/- 1.09 mm, P =.788) and restenosis rate (21% vs 20%, P = 1.000) were similar for direct stenting versus conventional stenting, respectively. IVUS demonstrated comparable intimal hyperplasia areas for direct versus conventional stenting (2.0 +/- 1.5 mm(2) vs 2.2 +/- 1.6 mm(2), respectively, P =.243). CONCLUSIONS: Direct stenting is highly feasible and results in similar vessel trauma and change in vessel morphology and acute lumen dimensions compared with stenting after predilatation. Similar acute angiographic and IVUS results persist at 6-month follow-up.

Aged↗
PubMed2005

Medication use and retinal vessel diameters.

PURPOSE: To study the influence of different medications on retinal vessel diameters. DESIGN: Cross-sectional study. METHODS: Retinal photographs in the Beaver Dam Eye Study (n = 4926, aged 43 to 84 years) were digitized, and the diameters of retinal vessels were measured. Participants' current medications were recorded at the examination. RESULTS: There were few significant associations between medication use and retinal vessel diameters. After adjusting for age, blood pressure, and other factors, participants who were using topical beta-blocker eyedrops had narrower retinal arteriolar (P = .05) and venular (P = .006) diameters than nonusers. Systemic beta-blocker was not associated with retinal vessel diameter size. CONCLUSION: We found few associations between current medication use and retinal vessel diameter. Retinal vessels were narrowed in those taking antiglaucoma medications, most strikingly in those prescribed topical beta-blockers, although such a relationship could not be established among those using systemic beta-blockers.

Adult↗
PubMed2006

Combining surgical ablation of retinal inflow and outflow vessels with photodynamic therapy for retinal angiomatous proliferation.

PURPOSE: To evaluate short-term efficacy of combining surgical ablation of retinal inflow and outflow vessels and photodynamic therapy (PDT) for stage 3 retinal angiomatous proliferation (RAP). DESIGN: Prospective interventional case series. METHODS: Five eyes (five patients) underwent surgical ablation of inflow and outflow vessels and PDT for stage 3 RAP. RESULTS: Inflow and outflow vessels were ablated in four eyes, and only inflow was ablated in one eye. In four eyes starting PDT within six weeks of surgical ablation, choroidal neovascularization (CNV) disappeared or shrank after one PDT session (three months follow-up). However, CNV enlarged again in three of the four (final follow-up) because of reperfusion from newly formed inflow vessels. In one eye starting PDT seven months after ablation, a new retinal inflow vessel feeding the CNV appeared by the time of the first PDT session. The CNV continued to expand, despite two PDT sessions. CONCLUSIONS: Combining surgical ablation and PDT was not useful on account of a high frequency of reperfusion from retinal inflow vessels.

Arterioles↗
PubMed2006

Total aortic arch replacement in patients with arch vessel anomalies.

BACKGROUND: The presence of anomalous arch vessels has considerable impact on aortic arch reconstruction techniques and cerebral protection methods when the separated graft technique is adopted to perform total arch replacement. We analyzed our experience of total arch replacement in patients with arch vessel anomalies. METHODS: Among the 220 patients undergoing total arch replacement at our institution, 21 patients (9.5%) had various arch vessel anomalies. Common brachiocephalic trunk was found in 8 patients (3.6%); an isolated left vertebral artery in 9 (4.1%); aberrant right subclavian artery in 3 (1.4%); and coexistent common brachiocephalic trunk and isolated left vertebral artery in 1 (0.5%). In 4 of the 9 patients with isolated left vertebral artery, preoperative diagnosis was possible with magnetic resonance angiography or three-dimensional computed tomography. In cases with common brachiocephalic trunk, total arch replacement could be performed with the usual techniques after separating the innominate and left common carotid arteries from each other. The isolated left vertebral artery was anastomosed to the left subclavian artery graft in 7 patients and to the native left subclavian artery in 2. In the aberrant right subclavian artery variety, a distal aortic anastomosis was performed distal to the orifice of this anomalous artery. The aberrant vessel was reconstructed on the right side of the trachea and esophagus. RESULTS: There was no early or in-hospital mortality. No neurologic complication attributable to the arch vessel anomalies was found. CONCLUSIONS: A precise preoperative diagnosis is very important for the selection of an appropriate surgical strategy in patients with arch vessel anomalies. Magnetic resonance angiography and three-dimensional computed tomography may be useful diagnostic tools in these patients.

Aged↗
PubMed2006

Engineered living blood vessels: functional endothelia generated from human umbilical cord-derived progenitors.

BACKGROUND: Tissue-engineered living blood vessels (TEBV) with growth capacity represent a promising new option for the repair of congenital malformations. We investigate the functionality of TEBV with endothelia generated from human umbilical cord blood-derived endothelial progenitor cells. METHODS: Tissue-engineered living blood vessels were generated from human umbilical cord-derived myofibroblasts seeded on biodegradable vascular scaffolds, followed by endothelialization with differentiated cord blood-derived endothelial progenitor cells. During in vitro maturation the TEBV were exposed to physiologic conditioning in a flow bioreactor. For functional assessment, a subgroup of TEBV was stimulated with tumor necrosis factor-alpha. Control vessels endothelialized with standard vascular endothelial cells were treated in parallel. Analysis of the TEBV included histology, immunohistochemistry, biochemistry (extracellular matrix analysis, DNA), and biomechanical testing. Endothelia were analyzed by flow cytometry and immunohistochemistry (CD31, von Willebrand factor, thrombomodulin, tissue factor, endothelial nitric oxide synthase). RESULTS: Histologically, a three-layered tissue organization of the TEBV analogous to native vessels was observed, and biochemistry revealed the major matrix constituents (collagen, proteoglycans) of blood vessels. Biomechanical properties (Young's modulus, 2.03 +/- 0.65 MPa) showed profiles resembling those of native tissue. Endothelial progenitor cells expressed typical endothelial cell markers CD31, von Willebrand factor, and endothelial nitric oxide synthase comparable to standard vascular endothelial cells. Stimulation with tumor necrosis factor-alpha resulted in physiologic upregulation of tissue factor and downregulation of thrombomodulin expression. CONCLUSIONS: These results indicate that TEBV with tissue architecture and functional endothelia similar to native blood vessels can be successfully generated from human umbilical cord progenitor cells. Thus, blood-derived progenitor cells obtained before or at birth may enable the clinical realization of tissue engineering constructs for pediatric applications.

Biomechanical Phenomena↗
PubMed2005

Histological characteristics of tumor cells and stromal cells in vessels and lymph nodes are important prognostic parameters of extrahepatic bile duct carcinoma: a prospective study.

Extrahepatic bile duct carcinomas (EHBDCs) consist of primary tumors, tumors in vessels, and tumors in lymph nodes. The purpose of this study was to prospectively investigate whether the histological characteristics of tumor cells and tumor stromal cells in vessels and lymph nodes were significantly associated with the outcomes of 60 EHBDC patients as compared with the histological characteristics of tumor cells and tumor stromal cells in primary tumors. Multivariate analyses, using the Cox proportional hazard regression model, showed that in EHBDCs without nodal metastasis, blood vessel tumor emboli with an angiomatous stroma significantly increased the hazard ratios (HRs) of tumor recurrence and death ( P < .05). In EHBDCs with nodal metastasis, the presence of tumor necrosis in the nodal tumors significantly increased the HRs of tumor recurrence and initial distant organ metastasis ( P < .05). In EHBDCs located in the distal to middle portion of the extrahepatic bile duct, blood vessel tumor emboli with an angiomatous stroma significantly increased the HRs of tumor recurrence, initial distant organ metastasis, and death ( P < .05). Severe nuclear atypia of the tumor cells in lymph vessels significantly increased the HRs of tumor recurrence and initial distant organ metastasis ( P < .05). In EHBDCs located in the hilar portion of the extrahepatic bile duct, the presence of nodal tumors with more than 4 mitotic figures significantly increased the HRs of tumor recurrence and initial distant organ metastasis ( P < .05). Several histological characteristics of tumor cells and tumor stromal cells in vessels and lymph nodes have significant effects on tumor progression of EHBDCs.

Adult↗
PubMed2006

Acrolein generation stimulates hypercontraction in isolated human blood vessels.

Increased risk of vasospasm, a spontaneous hyperconstriction, is associated with atherosclerosis, cigarette smoking, and hypertension-all conditions involving oxidative stress, lipid peroxidation, and inflammation. To test the role of the lipid peroxidation- and inflammation-derived aldehyde, acrolein, in human vasospasm, we developed an ex vivo model using human coronary artery bypass graft (CABG) blood vessels and a demonstrated acrolein precursor, allylamine. Allylamine induces hypercontraction in isolated rat coronary artery in a semicarbazide-sensitive amine oxidase activity (SSAO) dependent manner. Isolated human CABG blood vessels (internal mammary artery, radial artery, saphenous vein) were used to determine: (1) vessel responses and sensitivity to acrolein, allylamine, and H(2)O(2) exposure (1 microM-1 mM), (2) SSAO dependence of allylamine-induced effects using SSAO inhibitors (semicarbazide, 1 mM; MDL 72274-E, active isomer; MDL 72274-Z, inactive isomer; 100 microM), (3) the vasoactive effects of two other SSAO amine substrates, benzylamine and methylamine, and (4) the contribution of extracellular Ca(2+) to hypercontraction. Acrolein or allylamine but not H(2)O(2), benzylamine, or methylamine stimulated spontaneous and pharmacologically intractable hypercontraction in CABG blood vessels that was similar to clinical vasospasm. Allylamine-induced hypercontraction and blood vessel SSAO activity were abolished by pretreatment with semicarbazide or MDL 72274-E but not by MDL 72274-Z. Allylamine-induced hypercontraction also was significantly attenuated in Ca(2+)-free buffer. In isolated aorta of spontaneously hypertensive rat, allylamine-induced an SSAO-dependent contraction and enhanced norepinephrine sensitivity but not in Sprague-Dawley rat aorta. We conclude that acrolein generation in the blood vessel wall increases human susceptibility to vasospasm, an event that is enhanced in hypertension.

Acrolein↗
PubMed2004

Expression of cys-cys chemokine ligand 21 on human gingival lymphatic vessels.

The cys-cys (C-C) chemokine ligand 21 is a member of the C-C chemokines that constitute a group of heparin-binding cytokines with a pattern of four or six conserved cysteines. The CCL21 is known to be expressed in secondary lymphoid tissues, however it has rarely been reported for the expression on peripheral lymphatic vessels in somatic tissue. Here we investigated the expression of CCL21 on lymphatic vessels identified by anti-desmoplakin in uninflamed and inflamed human gingiva. In uninflamed tissue the expression of CCL21 was detected on lymphatic vessels in gingiva. In uninflamed gingiva the expression of CCL21 was detected on all lymphatic capillaries of the mucosal connective tissue papillae. There were two types of collecting lymphatic vessels in the lamina propria mucosae expressing CCL21 strongly or very weakly. In inflamed gingiva no expression of CCL21 was detected on lymphatic vessels. In all tissue sections no blood vessels expressing CCL21 were observed. These results may suggest that the expression of CCL21 is predominantly induced in the peripheral lymphatic endothelium of the uninflamed mucosal microcirculation, and that under inflamed conditions a reduction of CCL21 occurs in lymphatic endothelium.

Adolescent↗
PubMed2006

A pathological analysis of lymphatic vessels in early renal allograft.

Lymphatic vessels are an essential part of the immunological response. Nevertheless, little is known about the pathology of renal transplant rejection. In part the reason may be not distinguishing peritubular capillaries from lymphatic vessels by periodic acid-Schiff (PAS) staining. This study examined the morphology of lymphatic vessels in early renal allografts using double staining with PAS and podoplanin. The 41 cases were divided into four categories: (I) acute antibody-mediated rejection, (II) acute cellular rejection, (III) peritubular capillaritis only, and (IV) controls. I through III had the evidence of peritubular capillaritis exceeding grade 1 on a biopsy obtained an average of 17.3 +/- 5.5 days after kidney transplantation. In addition, each lymphatic vessel density (LVD) and nodular lesion of lymphocytes (NL) were quantified as the number of each podoplanin-positive vascular profiles and NL per unit area of cortex measured Lumina Vision (Mitani). The average of the LVD was 73.0, 35.1, 37.1, and 8.1 per 10 mm2 for groups I to IV and the average of NL was 2.8, 5.5, 1.3, 0.9, respectively. There was a significant correlation between LVD and NL. NL showed a strong relation to the accumulation of lymphocytes in lymphatic vessels (AL); 22% of the AL scores were greater than the peritubular capillaritis grade. We found lymphatic vessels to be strongly associated with any kind of inflammatory process that occurred unexpectedly soon after kidney transplantation. In addition, to avoid misdiagnosis of peritubular capillaritis, NL in early renal allograft must especially be excluded.

Adult↗
PubMed2005

Uniform overexpression and rapid accessibility of alpha5beta1 integrin on blood vessels in tumors.

Integrin alpha5beta1 is among the proteins overexpressed on tumor vessels and is a potential target for diagnostics and therapeutics. Here, we mapped the distribution of alpha5beta1 integrin in three murine tumor models and identified sites of expression that are rapidly accessible to intravascular antibodies. When examined by conventional immunohistochemistry, alpha5beta1 integrin expression was strong on most blood vessels in RIP-Tag2 transgenic mouse tumors, adenomatous polyposis coli (apc) mouse adenomas, and implanted MCa-IV mammary carcinomas. Expression increased during malignant progression in RIP-Tag2 mice. However, immunoreactivity was also strong in normal pancreatic ducts, intestinal smooth muscle, and several other sites. To determine which sites of expression were rapidly accessible from the bloodstream, we intravenously injected anti-alpha5beta1 integrin antibody and 10 minutes to 24 hours later examined the amount and distribution of labeling. The injected antibody strongly labeled tumor vessels at all time points but did not label most normal blood vessels or gain access to pancreatic ducts or intestinal smooth muscle. Intense vascular labeling by anti-alpha5beta1 integrin antibody co-localized with the uniform CD31 immunoreactivity of tumor vessels and contrasted sharply with the patchy accumulation of nonspecific IgG at sites of leakage. This strategy of injecting antibodies revealed the uniform overexpression and rapid accessibility of alpha5beta1 integrin on tumor vessels and may prove useful in assessing other potential therapeutic targets in cancer.

Animals↗
PubMedDate not supplied

The non-bleeding visible vessel versus the sentinel clot: natural history and risk of rebleeding.

Non-bleeding visible vessel and sentinel clot are terms used interchangeably to describe protuberances in the base of ulcers that have recently bled, but a consensus as to their definition or natural history does not exist. In patients with severe ulcer hemorrhage, non-bleeding protuberances were classified as vessels, with or without a small attached clot, or as sentinel clots, according to a schema based on the appearance of the protuberance at endoscopy but not subjected to pathologic correlation. Endoscopic therapy was not performed at the index endoscopic evaluation, and natural evolution was prospectively documented with daily videoendoscopy. Eleven (46%) of 24 patients with non-bleeding protuberances had rebleeding. Independent classification by three authors concurred in 18 (75%) of 24 lesions. Ten (91%) of 11 vessels with or without attached clot rebled versus 0 (0%) of 7 sentinel clots and 1 (17%) of 6 lesions without unanimous classification (p < 0.01, vessels versus other groups). Rebleeding occurred in 5 (71%) of 7 nonpigmented (pale or white), 6 (38%) of 16 red or purple, and 0 (0%) of 1 black protuberances. In general, vessels persisted until rebleeding, whereas sentinel clots disappeared within 1 to 3 days. We conclude that nonbleeding protuberances in ulcer bases can be separated into vessels, which have a high risk of rebleeding, and sentinel clots, which have a low risk of rebleeding.

Blood Coagulation↗