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Backgrounds: To evaluate the optical coherence tomography (OCT) biomarkers of patients with central serous chorioretinopathy (CSC) according to the presence or absence of direct anatomical relation to intervortex vein anastomosis (IVA) on indocyanine green angiography., Methods: We reviewed the records of 39 patients with chronic CSC. Patients were categorized in 2 groups: presence of IVA(Group A) or absence of IVA(Group B) in the macular region. Localization of IVA was categorized in 3 areas according to ETDRS grid:inner 1 mm circle (area-1), 1-3 mm middle circle (area-2) and 3-6 mm outer circle (area-3)., Results: There were 31 eyes in Group A,21 eyes in Group B. Mean age of the patients was 52.5 ± 11.3years in Group A,47.2 ± 11years in Group B(p<0.001).Mean initial visual acuity (VA) was 0.38±0.38LogMAR in Group A, 0.19±0.21LogMAR in Group B(p<0.001).Mean subfoveal choroidal thickness(SFCT) was 436.3 ± 134.3µ in Group A,480.2 ± 136.6µ in Group B(p<0.001).Localization of IVA in area-1 was correlated with inner choroidal attenuation (ICA) and leakage on IVA(p = 0.011,p = 0.02). Localization of IVA in area-3 was correlated with irregular lesions on RPE(p = 0.042).Smokestack configuration,intraretinal cysts and ICA were correlated with worse initial VA(p<0.001,p = 0.001 and p = 0.04).Shaggy subtype of photoreceptor disruption was associated with better initial VA(p = 0.003)., Conclusions: We detected older age, worse initial VA and thinner SFCT in patients with chronic CSC and macular region IVA(m-IVA). Long term follow-up of patients with and without m-IVA may exhibit the difference in treatment outcomes and development of neovasculopathy., (Copyright © 2023. Published by Elsevier B.V.)

Background: Unequal placental territory in monochorionic diamniotic twins is a primary cause of selective fetal growth restriction (sFGR), and vascular anastomoses play important role in determining sFGR prognosis. This study investigated differences in placental characteristics and pregnancy outcomes in cases of sFGR with and without thick arterio-arterial anastomosis (AAA)., Methods: A total of 253 patients diagnosed with sFGR between April 2013 and April 2020 were retrospectively analyzed. An AAA greater than 2 mm in diameter was defined as a thick AAA. We compared placental characteristics and pregnancy outcomes between cases of sFGR with and without thick AAA., Results: Prevalence of AAA, thick arterio-venous anastomosis (AVA), veno-venous anastomosis (VVA), and thick VVA were significantly higher in the thick AAA group relative to the non-thick AAA group (100.0 vs. 78.5%, P < 0.001; 44.3 vs. 15.4%, P < 0.001; 27.1 vs. 10.8%, P = 0.017, and 24.3 vs. 6.2%, P = 0.004, respectively). The total numbers of AVA and total anastomoses were significantly higher in thick AAA group relative to the non-thick AAA group (5 [1, 14] vs. 3 [1, 15, P = 0.016; and 6 [1, 15] vs. 5 [1, 16], P = 0.022, respectively). The total diameter of AAA, AVA, VVA, and all anastomoses in the thick AAA group was larger than in the non-thick AAA group (3.4 [2.0,7.1] vs. 1.4 [0.0, 3.3], P < 0.001; 6.3 [0.3, 12.0] vs. 2.5 [0.3, 17.8], P < 0.001; 4.2±1.8 vs. 1.9±1.2, P =0.004; and 10.7 [3.2,22.4] vs. 4.4 [0.5, 19.3], P < 0.001, respectively). Growth-restricted fetuses in the thick AAA group exhibited significantly increased birthweight relative to those in thenon-thick AAA group (1570 (530, 2460)g vs. 1230 (610, 2480)g, p = 0.002)., Conclusions: In the placentas associated with sFGR, thick AAA can co-occur with thick AVA and VVA, and placental angiogenesis may differ significantly based upon whether or not thick AAA is present. The birth weights of growth-restricted fetuses in cases of sFGR with thick AAA are larger than in cases without thick AAA., (© 2022. The Author(s).)

Introduction: To investigate the correlation between placental superficial anastomoses, placental territory and the umbilical cord attachment site with the time of onset of twin-to-twin transfusion syndrome (TTTS), and to explore the influence of placental characteristics on the time of onset of TTTS., Methods: A retrospective analysis was performed on 48 cases of TTTS managed conservatively at the Obstetrics Department of Peking University Third Hospital from April 2014 to April 2019. Placental superficial anastomoses, placental territory, the distance between the insertion points of the umbilical cord were measured after placental dye injection. Correlation analysis was conducted between placental characteristics and the time of onset of TTTS., Results: (1) The incidence of AA anastomoses was 33.3% (16/48) with a mean total diameter of 2.3 ± 1.4 mm, that of AV anastomoses was 95.8% (46/48) with a mean total diameter of 1.2 ± 0.4 mm, and that of VV anastomoses 22.9% (11/48) with a mean total diameter of 2.3 ± 1.1 mm (2) The time of onset of TTTS was positively correlated with the umbilical insertion ratio (Spearman correlation coefficient = 0.404, P = 0.004), but not correlated with the total diameter of anastomoses in the three different types, or with placental territory discordance., Discussion: The time of onset of TTTS was positively correlated with the umbilical insertion ratio, which suggest that the distance between umbilical cord insertion sites may affect the time of onset of TTTS. The smaller the distance between the umbilical cord insertion sites, the earlier the time of onset of TTTS is likely to be., Competing Interests: Declaration of competing interest We declare that we have no financial and personal relationships with other people or organizations that can inappropriately influence our work, there is no professional or other personal interest of any nature or kind in any product, service and/or company that could be construed as influencing the position presented in, or the review of, the manuscript entitled., (Copyright © 2020. Published by Elsevier Ltd.)

Objective: To compare the prevalence of intermittent absent or reversed end-diastolic flow (iAREDF) in the umbilical artery in appropriately grown monochorionic diamniotic (MCDA) pregnancies with and without proximate cord insertion (PCI), and to evaluate pregnancy outcome., Methods: The prevalence of iAREDF in MCDA pregnancies with PCI (n = 11) was compared with a control group without PCI (n = 33). PCI was defined as a distance between the cord insertions below the fifth percentile. Placental sharing, number, and diameter of anastomoses were assessed by placental examination. Pregnancy outcome was evaluated., Results: iAREDF was present in 7/11 PCI pregnancies, compared with 0/33 in the control group (P ≤ .01). All PCI pregnancies and 94% of controls had arterioarterial (AA)-anastomoses (P = .56), the diameter was larger in the PCI group, respectively 3.3 vs 2.1 mm (P = .03). Three cases with iAREDF had adverse outcome, two resulted in fetal death of which one with brain damage in the co-twin, another underwent early premature emergency section for fetal distress., Conclusion: iAREDF occurs in a large proportion of MCDA pregnancies with PCI and is related to the diameter of the AA anastomosis. We hypothesize that iAREDF in appropriately grown MCDA twin pregnancies reflects an unstable hemodynamic balance with an increased risk for fetal deterioration. Whether outcome in these pregnancies can be improved by altered management requires further investigation., (© 2020 The Authors. Prenatal Diagnosis published by John Wiley & Sons Ltd.)

With limited information about the coccygeal glomus found in classic textbooks, we deemed it necessary to review the subject. The illustrations presented in this article derive from four coccygeal glomera incidentally encountered during examination of pilonidal disease specimens. Familiarization with its microanatomical features may help to avoid inappropriate interpretation of this enigmatic structure., (Copyright © 2018 Società Italiana di Anatomia Patologica e Citopatologia Diagnostica, Divisione Italiana della International Academy of Pathology.)

An 8-month-old girl presented with vitreous hemorrhage, peripheral retinal arteriovenous anastomosis, and hypoplasia of the thumb. Magnetic resonance imaging of the brain showed multiple hyperintensities, cysts, and calcifications in the white matter. DNA testing showed a mutation in one allele of the CTC gene, supporting the diagnosis of cerebroretinal microangiopathy with calcifications and cysts (CRMCC), or Coats plus disease, despite which designation this condition can present without subretinal exudate. In infants with peripheral retinal vascular disease, neuroimaging can identify the characteristic abnormalities of CRMCC., (Copyright © 2017 American Association for Pediatric Ophthalmology and Strabismus. Published by Elsevier Inc. All rights reserved.)

Objectives: The aim of the study is to compare placental monochorionic angioarchitecture complicated with twin-oligohydramnios-polyhydramnios sequence (TOPS), twin anemia polycythemia sequence (TAPS), twin reversed arterial perfusion (TRAP) and selective intra uterine growth restriction (sIUGR) to normal uneventful monochorionic placenta., Methods: Between December 2012 and December 2015, monochorionic placenta has been studied at the multiple pregnancy care center of the Femme-Mère-Enfant Hospital in Lyon. Umbilical chords were catheterized and dye injected for macroscopic analysis of angioarchitecture at the anatomopathology department. Placentas treated with laser foetoscopic surgery were excluded., Results: A total of 126 placentas were injected in the post-partum period. In total, 95% (119/126) of the placentas presented arteriovenous anastomoses (AVA). Median number of AVA was 7. The prevalence of at least one velamentous cord insertion was higher in TOPS and selective intrauterine growth restrictions P<0.01 and P<0.01 respectively, compared to uneventful pregnancies. Arterio-arterial anastomoses (AAA) were present in 82.7% (77/93) of uneventful placentas versus 33.3% of TOPS (P<0.01) and 28.5% of TAPS (P<0.01). The prevalence of veno-venous anastomoses was significantly higher in TOPS (P<0.01). All TAPS placentas showed marginal arteriovenous anastomoses. In TRAP placenta, the acardiac twin had no specific vascular territory., Conclusion: The study confirms literature findings on prevalence of vascular anastomoses in monochorial placentas, suggesting the protective role of AAA in TOPS and TAPS. The role of VVA is yet hard to determinate. Macroscopic observations of monochorionic placentas are valuable and essential keys for understanding, managing and treating anastomotic syndromes., (Copyright © 2017 Elsevier Masson SAS. All rights reserved.)

Cell-based tissue engineering is a potential treatment alternative for organ replacement. However, the lack of a robust vasculature, especially in the context of diseases such as diabetes, is a major hindrance to its success. Despite extensive research on the effects of diabetes in angiogenic sprouting, its effects on vessel arterio-venous (AV) specification have not been addressed. Using an engineered tissue that yields functional vessels with characteristic AV identities, we demonstrate that type 1 diabetes negatively affects vessel AV specification and perivascular cell (PVC) coverage. Blockage of PVC recruitment in normoglycemia does not affect blood flow parameters, but recapitulates the vascular immaturity found in diabetes, suggesting a role for PVCs in AV specification. The downregulation of Jagged1 and Notch3, key modulators of endothelial-perivascular interaction, observed in diabetes support this assertion. Co-culture assays indicate that PVCs induce arterial identity specification by inducing EphrinB2 and downregulating EphB4. This is antagonized by high glucose or blockage of endothelial Jagged1. Engineered tissues composed of microvessels from diabetic mice display normal PVC coverage and Jagged1/Notch3 gene expression when implanted into non-diabetic hosts. These indicate a lack of legacy effect and support the use of a more aggressive treatment of diabetes in patients undergoing revascularization therapies., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Intimal thickening due to atherosclerotic lesions or intimal hyperplasia in medium to large blood vessels is a major contributor to heart disease, the leading cause of death in the Western World. Balloon angioplasty with stenting, bypass surgery, and endarterectomy (with or without patch reconstruction) are some of the techniques currently applied to occluded blood vessels. On the basis of the preponderance of clinical evidence that disturbed flow patterns play a key role in the onset and progression of atherosclerosis and intimal hyperplasia, it is of interest to analyze suitable hemodynamic wall parameters that indicate susceptible sites of intimal thickening and/or favorable conditions for thrombi formation. These parameters, based on the wall shear stress, wall pressure, or particle deposition, are applied to interpret experimental/clinical observations of intimal thickening. Utilizing the parameters as "indicator" functions, internal branching blood vessel geometries are analyzed and possibly altered for different purposes: early detection of possibly highly stenosed vessel segments, prediction of future disease progression, and vessel redesign to potentially improve long-term patency rates. At the present time, the focus is on the identification of susceptible sites in branching blood vessels and their subsequent redesign, employing hemodynamic wall parameters. Specifically, the time-averaged wall shear stress (WSS), its spatial gradient (WSSG), the oscillatory shear index (OSI), and the wall shear stress angle gradient (WSSAG) are compared with experimental data for an aortoceliac junction. Then, the OSI, wall particle density (WPD), and WSSAG are segmentally averaged for different carotid artery bifurcations and compared with clinical data of intimal thickening. The third branching blood vessel under consideration is the graft-to-vein anastomosis of a vascular access graft Suggested redesigns reduce several hemodynamic parameters (i.e., the WSSG, WSSAG, and normal pressure gradient [NPG]), thereby reducing the likelihood of restenosis, especially near the critical toe region.

Surgical procedures in the pelvic region are very challenging because of the complex anatomy of this region. "Corona mortis" is a term used to describe retro-pubic anastomosis between the obturator and external iliac vessels. It is considered as a key structure as significant haemorrhage may occur if the vessels are cut accidentally during pelvic surgeries. Earlier studies have documented a high frequency of venous anastomosis compared to its arterial counterpart. The objective of our study was to document the prevalence of venous corona mortis in South Indian human adult cadaveric pelvises. We conducted this study on 73 cadaveric pelvic halves. Out of the 73 hemi pelvises, 36 were normal without any variations of the obturator vessels while 37 hemi pelvises (51%) showed the presence of abnormal obturator vessels which proves to be a very high incidence in terms of variations. Out of the 37 hemi pelvises, 25 (68%) showed the presence of 2 obturator veins, out of which 1 was normal and the other was an abnormal obturator vein. 8 hemi pelvises (22%) had only abnormal obturator vein. Most of the abnormal obturator veins drained into the external iliac vein, while two veins drained into inferior epigastric veins. Venous corona mortis is said to be frequently encountered during surgery and is considered to be as important as arterial corona mortis in its clinical implications. Individual evaluation of this risky anatomical structure should be done prior to any surgical interventions., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Persistent primitive hypoglossal artery (PPHA) is a persistent carotid-basilar anastomosis. It rarely remains at birth. It occasionally may be a risk for ischemia and embolic infarction to the posterior cerebral circulation, especially in patients with carotid stenosis proximal to the origin of persistent primitive arteries. We describe a case of a 60-year-old woman with asymptomatic internal carotid artery (ICA) stenosis and ipsilateral PPHA successfully treated by carotid artery stenting (CAS). A few cases of CAS for ICA stenosis with PPHA have been reported, but the strategy and methods in each case were different because of its unique anatomy and hemodynamics. It is essential to prevent distal embolisms and preserve blood flow at the territory of both the ICA and PPHA. The protection method should be selected carefully. We review the literature and discuss appropriate treatment strategies., (© The Author(s) 2016.)

Objective: In monochorionic diamniotic (MCDA) twin pregnancies, unequal placental sharing does not always lead to adverse outcomes. The aim of this study is to investigate how unequal placental sharing may be compensated by placental anatomical changes., Methods: Between January 2012 and July 2013, a total of 60 uncomplicated MCDA pregnancies ending in live birth of healthy twins were studied. Placentas were divided into two groups; an equally shared placenta group (placenta territory discordance ≤ 25%, N = 40) and an unequally shared placenta group (placenta territory discordance >25%, N = 20). Angioarchitecture, cord insertion type and the distance between two cord insertions were compared., Results: Vascular anastomoses were seen in all 60 placentas, and 58 placentas (96.7%) had arterioarterial anastomoses (AA). The overall diameter of the AA was larger in the unequally shared placenta group as compared to the equally shared placentas (0.27 ± 0.12 cm versus 0.19 ± 0.1 cm, p < 0.05). The distance between the cord insertions was shorter in the unequally shared group (14.5 ± 6.0 cm versus 18.3 ± 6.5 cm, p < 0.05)., Conclusion: The absence of adverse outcomes in unequally shared placenta group can be explained by the presence of large AA and shorter distance between cord insertions, protecting the twin with the smaller placental part against growth restriction and other pathology.

We examined lung histology from 8 infants who died with meconium aspiration syndrome in order to determine the presence of intrapulmonary bronchopulmonary anastomotic pathways. Each infant required mechanical ventilation to treat hypoxemic respiratory distress. Lung histology from each infant shows evidence of prominent bronchopulmonary vascular connections., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Introduction: White matter disease occurs as a consequence of small vessel disease; however, hypoperfusion may also play a role. We investigated whether patients with less cerebral vessel anastomosis may develop more white matter disease., Methods: Magnetic resonance imaging (1.5t) with intracranial magnetic resonance angiography data was collected on a convenience sample between July 2008 and January 2009. All patients were independently assessed for circle of Willis variants by two researchers and categorized into two groups: those with a complete circle of Willis and those with an incomplete circle of Willis (absent vessels). The complete group was sub-divided into a classical group (entirely normal circle of Willis) and a hypoplastic group (hypoplasia but no absent vessels). White matter disease assessment was conducted for these groups, by two researchers blind to magnetic resonance angiography findings, on all patients over 50 years old., Results: The circle of Willis was characterized in 163 patients, while 90 (>50 years) underwent white matter disease assessment. The kappa inter-rater reliability between both circle of Willis assessors and between both white matter disease assessors was 0.57 and 0.63, respectively. The prevalence of circle of Willis variants strongly correlated with the seminal paper by Riggs and Rupp. Independent of age and gender, those with an incomplete circle of Willis (n = 68) exhibited 58% more white matter disease than those with a complete circle of Willis (n = 22) (white matter disease score 6.52 vs. 4.11, respectively, P = 0.03). Patients with absent anterior vessels exhibited more frontal white matter disease than those with intact anterior vessels (3.7 vs. 1.72, P < 0.001). Patients with absent posterior vessels exhibited more occipital white matter disease than those with intact posterior vessels (2.52 vs. 1.34, P = 0.014)., Conclusion: These data suggest that congenital absence of anastomotic capacity correlates with incident white matter disease, thus alluding to a hypoperfusion mechanism in the development of white matter disease., (© 2013 The Authors. International Journal of Stroke © 2013 World Stroke Organization.)

Aims: This study reports long-term outcomes after endovascular salvage (EVS) for acute dialysis fistula/graft dysfunction., Methods: All patients presenting with acute fistula or graft dysfunction, excluding primary failures, referred for endovascular salvage were included in this single-centre prospective study., Results: Altogether, 410 procedures were carried out in 232 patients. Overall, the incidence of thrombosis/occlusion (per patient-year) was 0.12 for fistulae and 0.9 for grafts. The anatomical success rate for EVS was 94% for fistulae and 92% for grafts. Primary patency rates for fistulae at 1, 6, 12, 24 and 36 months were 82, 64, 44, 34 and 26%, respectively, whereas secondary patency rates were 88, 84, 74, 69 and 61%, respectively. Primary patency rates for grafts at 1, 6 and 12 months were 50, 14 and 8%. The overall rate of complications was 6% with no incidence of symptomatic pulmonary embolism. In a Cox regression model, upper-arm location of fistula (HR 1.9, p = 0.04, n = 144) was associated with lower primary patency, whereas the presence of thrombosis was associated lower primary (HR 1.9, p = 0.004, n = 144) and secondary patency (HR 3.7, p < 0.001, n = 144). Aspirin therapy was associated with longer primary patency (HR 0.6, p = 0.02, n = 144) and secondary patency (HR 0.58, p = 0.08, n = 144)., Conclusion: EVS is effective but longer-term outcomes are poor. Presence of thrombosis portends poor fistula survival and strategies for prevention need attention. Balloon maceration, our preferred declotting technique, is safe and the most cost-effective method. Aspirin therapy for patients presenting with failure of fistulae deserves further investigation., (© 2015 S. Karger AG, Basel.)

Background: Hemorrhage is a major category of the clinical symptoms of moyamoya disease (MMD). Intracerebral and intraventricular hemorrhages are the most common hemorrhages in MMD, and subarachnoid hemorrhages (SAHs) are notably rare. There have only been a few previous case reports of this imaging manifestation. In the present study, we investigated the clinical and neuroimaging features of MMD patients who presented with SAH and sought to identify the possible causes of hemorrhage., Methods: The right and left cerebral hemispheres of each patient were identified as hemorrhagic or non-hemorrhagic. Each hemisphere was assessed for Suzuki stage, and dilatation and branch extension of the anterior choroidal artery (AChA) and posterior communicating artery (P-CoM) and for the degree of transdural anastomosis and posterior circulation compensation. Next, these data were statistically analyzed for correlations with the SAH events., Results: In 34 of 349 hemorrhagic MMD patients, the first episode of hemorrhage was a SAH, among which, 26 (76.5%) patients were women and there was only one pediatric patient. The Suzuki stage was not statistically correlated with the SAH events. There were also no correlations between SAH and dilatation or abnormal branching of the AChA and P-CoM. In contrast, SAH and transdural anastomosis were correlated. 25 of the 34 hemorrhagic hemispheres (73.5%) were positive for transdural anastomosis, and this number was 15 (44.1%) in the non-hemorrhagic hemispheres; this difference was statistically significant (P<0.05)., Conclusions: SAH is an important type of hemorrhage in MMD patients and ranks as the fourth most common type after intracerebral hemorrhage (ICH), intraventricular hemorrhage (IVH), and ICH + IVH. It mainly occurs in adult women, and the rupture of the transdural anastomosis might be the main cause of this condition.

Objective: In the last 10 years with the advances in microsurgery of techniques and materials the indications for free tissue transfer have considerably been increased. But, there are still some limitations and drawbacks. Among risk factors associated with flap failure, atherosclerosis can affect both the flap and the recipient vessels of free microvascular tissue transfers. The purpose of this paper is to discuss about the pathogenesis of Monckeberg's sclerosis, and the topics that must be taken into consideration when performing microsurgery in these patients., Methods: PubMed database was searched using Mesh. The following terms was added to the search builder: Monckeberg's sclerosis, free flap. The Boolean operator "AND" was selected. All the selectable Mesh headings for "Monckeberg's sclerosis" and "free flap" were included., Results: Almost all the literature works about microsurgery in Monckeberg's sclerosis patient show the importance of an accurate preoperative and postoperative evaluation and of a proper surgical technique., Conclusions: When adequate preoperative evaluation, surgical technique and postoperative monitoring are performed, even severe atherosclerosis should not be considered an absolute contraindication for microvascular surgery.

Anastomosing hemangioma, a benign vascular neoplasm histologically simulating angiosarcoma, is newly recognized and has been described primarily in the genitourinary tract. Here, we present a case of renal anastomosing hemangioma originating in the left kidney of a 32-year-old Chinese man with detailed computerized tomography (CT) and enhanced CT image information. The patient had no obvious signs and symptoms. The tumor was incidentally found by color Doppler imaging during a routine heath check-up. Subsequently, a detailed CT and an enhanced CT scan were performed. The tumor was well demarcated, and mahogany brown lesions, which measured 2.6 cm in maximum diameter, were observed. Microscopically, the tumor shows a lobular architecture with alternating cellular areas composed of anastomosing sinusoidal capillary-sized vessels lined by hobnail endothelial cells and edematous, hyaline paucicellular areas. Cytologically, the tumor cells were generally bland and exhibited positivity for CD31 and CD34 immunohistochemically. The patient had good status without evidence of tumor recurrence 21 months after the surgery. We suggest that more attention should be focused on this rare renal hemangioma variant and that it should not be over-diagnosed as a malignance, particularly an angiosarcoma., Virtual Slides: The virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/13000&#95;2014&#95;159.

Background: A persistent primitive hypoglossal artery (PHA) is a rare congenital caroticobasilar anastomosis with a reported prevalence of 0.027%-0.26%. Intracranial aneurysms occur with a frequency of approximately 26% in the setting of PHAs., Case Description: PHAs typically originate from the proximal cervical internal carotid artery. To date, however, six cases of PHAs originating from the external carotid artery have been reported. We present the first case of a PHA originating from the external carotid artery associated with subarachnoid hemorrhage., Conclusion: We review the literature and discuss anatomic implications with respect to the extreme lateral infrajugular transcondylar exposure for clip ligation of a ruptured posterior inferior cerebellar artery aneurysm in the setting of a PHA., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Background Intracranial arterial variations are a frequent finding in the general population. Knowledge of these vascular variations has significant clinical impact because some of them predispose patients to development of an aneurysm or cerebrovascular ischemic disease. The purpose of this study was to evaluate the frequency of intracranial vascular variations and associated vascular lesions on computed tomography angiography (CTA) examinations. Material and Methods CTA examinations performed by 16-detector computed tomography were prospectively reviewed in 455 patients for the presence of fenestrations, duplications, hypoplasia, aplasia, aneurysms, and other vascular lesions. Results Arterial fenestrations were found in 2.4% of patients, with the vertebrobasilar system as the most common location. The remaining fenestrations were located on the middle cerebral artery M1 segment (0.2%), anterior communicating artery (0.4%), and anterior cerebral artery A1 segment (0.6%). No associated aneurysms were noted in these patients. The prevalence of an azygos anterior cerebral artery was 1.5%. Bihemispheric anterior cerebral artery was found in 0.9%, hypoplastic A1 segment in 17.6%, and congenital absence of A1 segment in 0.4% of patients. Fetal origin of the posterior cerebral artery was found in 37% of cases. Hypoplastic vertebral artery terminating as posterior inferior cerebellar artery was observed in 9 patients, while transversal anastomosis between vertebral arteries was seen in only 1 patient. Conclusions CTA precisely demonstrates the diversity of intracranial arterial variations, whose overall frequency in this study is similar to previous radiological reports. Furthermore, our results do not show significant association between the frequency of aneurysms and cerebral arterial anomalies.

Diffuse alveolar hemorrhage (DAH) is a life-threatening condition requiring urgent treatment. There are many different treatment-relevant causes of DAH, making the diagnostic approach to these patients complex and necessitating a multidisciplinary team. We report the case of a kidney transplant recipient in whom all diagnostic efforts did not reveal the cause of DAH, and only autopsy was able to establish an unexpected diagnosis., (© 2014 S. Karger AG, Basel.)

Objective: This study aimed to compare the angio-architecture of monochorionic placentas of spontaneous twin anaemia-polycythemia sequence (TAPS) with placenta of twin-to-twin transfusion syndrome (TTTS) with residual anastomoses after laser coagulation and placentas of uncomplicated monochorionic twin pregnancies., Methods: This case-control study compares the angio-architecture of monochorionic placentas of spontaneous TAPS (n = 12) with that of monochorionic placentas of TTTS treated by laser coagulation with residual anastomoses (TTTS + RA; n = 20) and placentas of monochorionic pregnancies without complications (n = 24), matched for gestational age. Placental sharing and angio-architecture were assessed by injection of colored dye., Results: The median diameter of the arterio-venous (AV) anastomoses in TAPS placentas was 2.26, 0.215 with TTTS + RA and 4.17 mm in normal monochorionic pregnancies (p < .03). The mean diameter of the arterio-arterial (AA) anastomoses in monochorionic placentas with spontaneous TAPS was 0.2 mm versus 0.15 mm in TTTS + RA and 2.0 mm in normal pregnancies, respectively (p < 0.03, p < 0.007). The number of AA anastomoses was lower with TAPS (0.3 versus 0.50 and 1, respectively, p < 0.015, p < 0.0001). Besides, unequal sharing was more frequent in TAPS as compared with monochorionic normal pregnancies (75% versus 29%, p = 0.03)., Conclusion: Age matched placentas of spontaneous TAPS are characterized by very small AV anastomoses and very few AA anastomoses of smaller diameter than placentas of monochorionic twins with TTTS or without obvious complications., (© 2013 John Wiley & Sons, Ltd.)

Rationale: Bronchopulmonary dysplasia (BPD) is the chronic lung disease of infancy that occurs in premature infants after oxygen and ventilator therapy for acute respiratory disease at birth. Despite improvement in current therapies, the clinical course of infants with BPD is often characterized by marked hypoxemia that can become refractory to therapy. Preacinar anatomic and functional communications between systemic and pulmonary vascular systems has been established in fetal lungs, but whether increased intrapulmonary anastomotic vessels or their failure to regress after birth contributes to hypoxemia in preterm infants with BPD is unknown., Objectives: We sought to find histologic evidence of intrapulmonary anastomotic vessels in lungs of patients who died of severe BPD., Methods: We collected lung tissues from fatal BPD cases and performed histology, immunohistochemistry, and high-precision three-dimensional reconstruction techniques., Measurements and Main Results: We report histologic evidence of intrapulmonary vessels that bridge pulmonary arteries and veins in the distal lungs of infants dying with severe BPD. These prominent vessels appear similar to "misaligned pulmonary veins" described in the lethal form of congenital lung disorder, alveolar capillary dysplasia., Conclusions: We found striking histological evidence of precapillary arteriovenous anastomotic vessels in the lungs of infants with severe bronchopulmonary dysplasia. We propose that persistence or expansion of these vessels after premature birth provides the anatomic basis for intrapulmonary shunt and hypoxemia in neonates with severe bronchopulmonary dysplasia and may play a significant role in the morbidity and mortality of BPD.

Introduction: Most monochorionic (MC) twin pregnancies have an uncomplicated course, but some develop severe complications including selective intrauterine growth restriction (sIUGR), twintwin transfusion syndrome (TTTS) and twin anemia-polycythemia sequence (TAPS). The underlying pathogenesis of these various complications is associated with the ubiquitous presence of vascular anastomoses in MC placentas., Methods: The aim of this study was to estimate the prevalence, number, size and localization of the anastomoses in sIUGR, TTTS and TAPS placentas compared to normal MC placentas using color dye injection. We excluded MC twin pregnancies treated with fetoscopic laser surgery or selective feticide., Results: A total of 235 placentas fulfilled the inclusion criteria: 126 normal MC, 47 TTTS, 46 sIUGR and 16 spontaneous TAPS. Median number of anastomoses in normal MC, sIUGR, TTTS and TAPS placentas was 8 (IQR: 4-12), 8 (IQR: 5-14), 7 (IQR: 5-11) and 4 (IQR: 3-5), respectively. The prevalence of arterio-arterial (AA) anastomoses in normal MC, sIUGR, TTTS and TAPS placentas was 96%, 98%, 47% and 19%, respectively. We found AV anastomoses to be evenly distributed along the vascular equator in all MC placentas except in TAPS cases, where anastomoses were mostly localized near the margin. We also found that, in sIUGR and TTTS placentas, AA anastomoses tended to be at the center of the placenta., Conclusion: The present study shows that the prevalence, size, number and localization of the various types of anastomoses differ between normal MC, sIUGR, TTTS and TAPS placentas., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Objective: To study the placental vascular distribution of monochorionic (MC) twins with twin-to-twin transfusion syndrome (TTTS) or birth weight discordance., Methods: Twenty-eight MC placentas were injected in Peking University Third Hospital between Feb. 2010 and Feb. 2011. The vascular distribution type (parallel, crossed, mixed and monoamniotic), the anastomosis of vessels and the placental sharing were recorded. The outcome of pregnancy and the placental characteristics of birth weight discordance (birth weight discordance≥20%) in non-TTTS MC twins were analyzed., Results: (1) The outcome of pregnancy: the miscarriage or gestational weeks of 28 MC twins were 20 to 38 weeks (median of 35 weeks). Six cases were TTTS, 3 of which received fetoscopic laser occlusion of communicating vessels (FLOC). There were 48 live births, with an average birth weight of (2036±623) g. (2) Type of placental vascular distribution:in the 28 MC placentas, number of parallel, crossed, mixed and monoamniotic type of placental vascular distribution were 4 (14%), 14 (50%), 6 (21%) and 4 (14%) cases, respectively. No parallel type was found in TTTS. There was no significant difference of vascular anastomosis or unequal placental sharing among the different placental vascular distribution types (P>0.05). (3) Characteristics of placental vascular distribution in birth weight discordance twins:there were 20 non-TTTS MC twin pregnancies, all of which got live births of both babies. Birth weight discordance equal to or more than 20% was found in 6 pairs of newborns, while birth weight discordance less than 20% was found in the rest 14 cases. Ratio of unequal placental sharing was significantly different between the two groups (P<0.01). There was no significant difference of umbilical cord insertion, placental vascular distribution and anastomosis in the two groups (P>0.01)., Conclusions: Vascular distribution type of MC twins might be related to TTTS. Unequal placental sharing is a risk factor of birth weight discordance in non-TTTS MC twins.

Introduction: Twin anemia-polycythemia sequence (TAPS) may occur in monochorionic twins either spontaneously or after laser surgery for twin-twin transfusion syndrome. Our aim was to analyze the placental angioarchitecture in spontaneous versus post-laser TAPS., Methods: We included all monochorionic twin placentas with spontaneous or post-laser TAPS injected at our center between 2002 and 2012. Placental angioarchitecture was evaluated using colored dye injection., Results: A total of 600 monochorionic placentas were injected during the study period of which 43 (7.2%) with TAPS (spontaneous TAPS, n = 16; post-laser TAPS, n = 27). Almost all anastomoses (96%; 119/124) were very small (diameter <1 mm) and the majority was localized near the placental margin. The median number of anastomoses per placenta was 4 (interquartile range (IQR): 3-5) in the spontaneous TAPS group and 2 (IQR: 1-3) in the post-laser TAPS group (p = 0.003). Arterio-arterial (AA) anastomoses were detected in 14.0% (6/43) of TAPS placentas and were all minuscule (diameter <1 mm). The rate of AA anastomoses in the spontaneous TAPS group and post-laser TAPS group was 18.8% (3/16) and 11.1% (3/27), respectively (p = 0.184)., Discussion: Spontaneous TAPS placentas have a significantly higher total number of anastomoses compared to post-laser TAPS placentas. Most anastomoses were localized near the margins of the placenta. Minuscule AA anastomoses were detected sporadically in both groups and the rate of AA anastomoses is slightly higher in the spontaneous TAPS group than in the post-laser group., Conclusion: Spontaneous TAPS placentas have a different placental angioarchitecture than post-laser TAPS placentas in terms of number and type of vascular anastomoses., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Purpose: To determine the feasibility of using ferumoxytol-enhanced magnetic resonance (MR) angiography to depict the vasculature of hemodialysis fistulas and improve image quality compared with nonenhanced time-of-flight (TOF) MR angiography., Materials and Methods: The study was institutional review board approved and was in compliance with HIPAA regulations. All participants provided written informed consent. TOF and first-pass ferumoxytol-enhanced MR angiography were performed in 10 patients with upper extremity autogenous fistulas. Ferumoxytol was administered as a bolus solution containing 430 μmol of elemental iron. A qualitative comparison was performed on maximum intensity projection images. Lumen depiction was evaluated by using a five-point scale. The uniformity of intraluminal signal intensity was measured as the ratio between the mean signal intensity of the entirety of the imaged fistula and its standard deviation. The contrast-to-noise ratio (CNR) between intraluminal signal and adjacent tissue was evaluated as a function of image acquisition time. Lumen depiction scores, luminal signal heterogeneity, and CNR efficiency were compared between TOF and ferumoxytol-enhanced MR angiography by using a Wilcoxon-Mann-Whitney test., Results: Flow artifacts were greatly reduced by the use of ferumoxytol-enhanced MR angiography. Ferumoxytol-enhanced MR angiography had significantly better performance than TOF MR angiography as measured with the following: lumen depiction scores in all segments (mean, 4.7±0.1 [standard error of the mean]; vs 3.0±0.3 for arterial inflow, 4.1±0.3 vs 1.9±0.3 for arterial outflow, 3.7±0.3 vs 1.8±0.2 for anastomosis, and 4.5±0.2 vs 2.1±0.2 for venous outflow; P<.001), intraluminal signal homogeneity (0.3±0.02 vs 0.4±0.06, P=.005), and CNR efficiency in the venous outflow (5.1±0.6 vs 2.5±0.4, P=.01)., Conclusion: This study demonstrates the feasibility of using ferumoxytol-enhanced MR angiography in imaging hemodialysis fistulas with consistently superior image quality compared with nonenhanced TOF MR angiography., (© RSNA, 2012)

We performed a matched case-control study to analyze the placental angioarchitecture, in particular the diameter of arterio-arterial (AA) anastomoses in monochorionic placentas from pregnancies with twin-twin transfusion syndrome (TTTS) compared to a control group of uncomplicated monochorionic placentas. Placental angioarchitecture was analyzed using colored dye injection. AA anastomoses were detected in 37% (14/38) of TTTS placentas versus 91% (209/228) in control placentas (p < 0.001). The median diameter of AA anastomoses in the group with and without TTTS was 1.9 mm and 2 mm, respectively (p = 0.711). In conclusion, our findings show that AA anastomosis occur less frequently in TTTS placentas, supporting the concept of the protective role of AA anastomoses in TTTS. However, the size of the AA anastomosis, when present, does not appear to influence the pathophysiology of the disease., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Purpose: Since certain surgical procedures still require a sitting or reverse Trendelenburg position, it remains important to evaluate the risk for paradoxical embolization. Intracardiac shunting, the most common cause being a patent foramen ovale, can be excluded by contrast-enhanced transesophageal echocardiography. There are, however, less described cases which result from patency of intrapulmonary functional arteriovenous anastomoses and lead to extra-cardiac paradoxical air embolism during anesthesia. We report a unique case to increase awareness of this real and potentially dangerous complication., Clinical Features: A 52-yr-old male was scheduled for resection of a tumour at the cerebellopontine angle. Preoperative evaluation excluded intracardiac shunts. During a craniotomy in the sitting position, recurrent venous air emboli entered the patient's right heart, leading to a sudden decline in end-tidal CO(2), an increase in PaCO(2), and a reduction of PaO(2). The exact source of surgical entrance could not be identified; therefore, the surgical wound was closed provisionally and the patient was repositioned supine to prevent further venous air emboli. During transition to the supine position, we observed clinically significant crossover of air into the left heart originating from the left pulmonary vein, as detected by transesophageal echocardiography. In all likelihood, the etiology was an opening of intrapulmonary right-to-left anastomoses. The patient recovered without neurological or pulmonary sequelae., Conclusion: In the presence of massive venous air emboli, intrapulmonary right-to-left paradoxical air emboli can occur while intraoperatively transitioning a patient from the sitting to the supine position.

Purpose: To evaluate the feasibility of using covered stents vs. bare stents in a model of central vein stenosis with an arteriovenous graft created to mimic the conditions in hemodialysis patients., Methods: In 7 mongrel dogs, an expanded polytetrafluoroethylene-covered nitinol stent was placed in one common iliac vein and a bare stent was placed in the contralateral vein. Arteriovenous grafts were created bilaterally between the common femoral artery and vein to induce endothelial damage. Neointima formation in the covered stents was compared to the bare stents at 12 weeks using microscopy and histochemical staining., Results: Two dogs were excluded due to thrombosis and infection of the arteriovenous grafts, but all stents in the remaining 5 dogs were patent. Smooth, complete neointimal coverage was observed on the inner surface of all the covered stents without intraluminal thrombus. In contrast, incomplete neointimal coverage was seen in all bare stents, with small focal thrombi adhering to the neointima on 3 bare stents. Focal nodular neointimal hyperplasia with denudation of the endothelium was observed in only 2 bare stents. Mean neointimal thickening was significantly greater in the covered stents. Eccentric neointimal thickening was observed at the inflow and outflow segments of both types of stents., Conclusion: Covered stents are technically feasible for the treatment of central vein stenosis, and they demonstrate complete, smooth neointimal coverage in normal central veins, but they also display greater neointimal thickening than bare stents.

An atypical case of abdominal vasculature, found in a 58-year-old woman is presented. The multidetector computed tomography angiogram revealed a large tortuous anastomotic vessel between the stem of the celiac trunk and the left colic artery, supplying branches for the left colon and pancreatic body and tail. We propose a simple embryological explanation for the development of this aberrant artery--the longitudinal ventral anastomosis, which connects the precursors of principal visceral arteries in a loop-like manner, loses its direct communication with the superior mesenteric artery but maintains its continuity above and below this level. This variation could pose a problem for radiological interpretation and affect surgical approaches to the aorta, left colon, and the pancreas., (Copyright © 2010 Wiley-Liss, Inc.)

Up to 21% of diamniotic-monochorionic twin pregnancies are complicated by severe birth weight discordance in the absence of twin-to-twin transfusion syndrome, a serious condition termed 'selective' birth weight discordance. While its pathogenesis remains incompletely understood, the development of selective intertwin growth discordance, related to fetal growth restriction of one twin, is generally attributed to aberrant placental characteristics. The aim of this study was to characterize the placental markers of selective birth weight discordance, with special emphasis on the choriovascular architecture. A prospective cohort of 319 consecutive diamniotic/monochorionic twin placentas was examined at Women and Infants Hospital between 2001 and 2009. After exclusion of placentas from pregnancies complicated by twin-to-twin transfusion syndrome (TTTS), monoamniotic, multiple and disrupted placentas, 216 placentas (36 birth weight (BW)-discordant and 180 BW-concordant) formed the subject of this study. Following dye injection, the anatomic characteristics and choriovascular anastomotic patterns of BW-discordant and BW-concordant placentas were compared. The BW-discordant placentas showed significantly higher frequencies of velamentous cord insertion (22% versus 8%, P < 0.001) and uneven placental sharing (56% versus 19%, P < 0.0001) compared with BW-concordant placentas. The frequencies of intertwin AA, VV and AV anastomoses, the net number of AV anastomoses, and the net cross-sectional area of AV anastomoses were similar in both groups. There was no correlation between the frequency of velamentous cord insertion and degree of placental sharing or patterns of choriovascular anastomoses in either group. In conclusion, velamentous cord insertion and uneven placental sharing are the two major placental determinants of selective birth weight discordance in diamniotic-monochorionic twins. The role of the intertwin anastomoses, even when unbalanced, is likely negligible. Elucidation of the mechanisms whereby velamentous cord insertion affects fetal growth may lead to more focused and effective therapeutic strategies for twin and singleton pregnancies complicated by dysregulated fetal growth., ((c) 2010 Elsevier Ltd. All rights reserved.)

Twin-to-twin transfusion syndrome (TTTS) is a multifactorial disorder that develops in 9-15% of diamniotic-monochorionic twin gestations. While the pathogenesis of TTTS remains poorly understood, unbalanced deep artery-to-vein (AV) anastomoses have traditionally been implicated in the gradual shift of blood from donor to recipient. The aim of this study was to define the placental markers of twin-to-twin transfusion syndrome, with special emphasis on the deep AV anastomoses. A prospective cohort of 284 consecutive diamniotic/monochorionic twin placentas was examined at Women and Infants Hospital between 2001 and 2008. Following exclusion of monoamniotic, multiple, disrupted and laser-treated placentas, 218 twin placentas (21 TTTS and 197 non-TTTS controls) formed the subject of this study. Placentas were injected with color-coded dyes. Anatomic characteristics and choriovascular anastomotic patterns of TTTS placentas were compared with non-TTTS controls. The TTTS placentas showed significantly higher frequencies of velamentous cord insertion, magistral vascular distribution patterns, uneven placental sharing, absence of AA anastomoses and presence of VV anastomoses. Deep AV anastomoses were identified in >or=95% of TTTS and non-TTTS placentas and were overall more abundant than previously reported. The total and net numbers of AV anastomoses were similar in both groups. However, the net cross-sectional area of AV anastomoses, which also takes into account the caliber of the vessels, was significantly smaller in TTTS placentas. There was no correlation between the direction of the AV imbalance and the twin donor/recipient status. In conclusion, TTTS has distinct placental characteristics, warranting their routine inclusion in the diamniotic-monochorionic placental pathology report. Our findings suggest imbalance of AV anastomoses is not required for the development for TTTS, although their presence, whether balanced or unbalanced, may contribute to the creation or perpetuation of the syndrome. Elucidation of the role of the various placental determinants in diamniotic-monochorionic twin gestations may lead to further refinement of therapeutic strategies., (Copyright 2009 Elsevier Ltd. All rights reserved.)

Monochorionic twin pregnancies are associated with increased perinatal morbidity and mortality. The vascular placental anastomoses in these pregnancies can cause severe complications. We describe a case of twin anemia-polycythemia sequence (TAPS) with an atypical placental angioarchitecture. During pregnancy serial ultrasound examinations of both twins revealed no amniotic fluid discordance and no abnormal Doppler ultrasound measurements (umbilical cord pulsatility index and middle cerebral artery peak systolic velocity). The twins, born at 33 + 3 weeks gestation after spontaneous onset of labour, were found to be anemic and polycythemic, respectively. Placental examination with colored dye injection showed, apart from small ateriovenous anastomoses, an arterio-arterial anastomosis. As arterio-arterial anastomoses have not been described in cases with spontaneous TAPS to date, it was postulated that such anastomoses carried a protective effect against the development of this complication., (2009 Elsevier Ltd. All rights reserved.)

Purpose: The purpose of this study was to analyze the angiographic (confocal scanning laser ophthalmoscopy technology) and corresponding (eye-tracked) spectral-domain optical coherence tomography (SD-OCT) features and to propose a classification for the progressive phases establishing retinal-choroidal anastomosis (RCA)., Methods: We reviewed all consecutive eyes with RCA that underwent Heidelberg Retina Angiograph angiography and tracked Spectralis SD-OCT at the University Eye Clinic of Creteil between September 2007 and March 2009., Results: Twenty-six eyes of 23 patients (8 men and 15 women, aged 70-88 years) showing RCA naïve to any treatment were included for analysis. In 6 of 7 eyes showing a discrete focal hyperfluorescence (focal staining), the corresponding (eye-tracked) SD-OCT scan showed a focal retinal pigment epithelium (RPE) erosion ("erosion sign") over a small, localized RPE elevation (which appeared filled with a hyperreflective material); in 7 of 8 eyes showing a typical "hot spot" in the late angiographic frames (focal leakage) and absence of a serosanguineous pigment epithelium detachment, the corresponding (eye-tracked) SD-OCT scan showed a focal RPE break leaving 2 free RPE flaps ("flap sign") at the level of a small, localized RPE elevation. In 10 of 11 eyes showing a typical hot spot in the late angiographic frames and presence of a serosanguineous pigment epithelium detachment, the corresponding (eye-tracked) SD-OCT scan showed, at the level of a large serosanguineous RPE detachment, a focal funnel-shaped RPE joining (kissing) an inverted focal funnel-shaped inner neuroepithelium ("kissing sign")., Conclusion: An early neovascularization (a discrete focal hyperfluorescence) arising from the choroid initially simply erodes the basement membrane/RPE (erosion sign; Phase 1) and later breaks the basement membrane/RPE (flap sign), infiltrating first into the outer retina forming an early RCA (Phase 2, a typical hot spot without a serosanguineous pigment epithelium detachment) and later into the inner retina (kissing sign) forming an established RCA (Phase 3, a typical hot spot with a serosanguineous pigment epithelium detachment).

The purpose of the study was to compare angiogenic response of isolated saphenous and epigastric arteriovenous bundles in avascular environment, in an in-vivo model. Saphenous and epigastric bundles of 20 rats were dissected and ligated distally. The bundles were implanted into silicone tubing to create a biologically neutral environment. Gross and histologic examination was performed at different intervals. No thrombus was detected in any of bundles prior to 24 hours. An adherent thrombus was seen at 24 hours in all ligated saphenous bundles; it persisted at three weeks with no evidence of neovascular sprouting. The ligated epigastric bundles remained patent with evidence of neovascular sprouting. The saphenous vessels are more likely to thrombose and do not show vascular proliferation when placed in an isolated environment, whereas the epigastric vessels are likely to remain patent and show vascular proliferation.

Background: Various types of revascularization surgery have been performed for moyamoya disease. Although the efficacies of these operations are well recognized, the optimal operative procedure remains undecided. In this report, we describe our modified surgical revascularization procedure for moyamoya disease and retrospectively analyze the results of such surgeries on six sides in six adult patients., Methods: Our operative procedure, combining direct and indirect bypasses, is a superficial temporal artery to middle cerebral artery anastomosis with encephalo-duro-myo-synangiosis. The encephalo-duro-myo-synangiosis is an indirect bypass combining the encephalo-duro- and encephalo-myo-synangioses. This operative procedure has been used routinely in adult patients since 2002., Results: Perioperative complications were noted in one of the six operations. This complication was transient and no attributive lesions were detected on CT or MRI. Revascularization was seen in cerebral blood flow studies in all patients, and the clinical outcomes were excellent or good. Effective neovascularization through the grafts was observed in all patients in follow-up angiographies., Conclusions: This operative procedure provides needed revascularization and prevents ischemic deficits. This modified procedure is useful for responding to subsequent additional ischemia in the area of the anterior cerebral artery and should be considered one of the optimal procedures for treating moyamoya disease.

Purpose: Implantation of vascular bundles into ischemic tissue as a means of revascularization has been performed for many decades, but there is considerable confusion regarding its clinical utility. We believe that the varying results quoted in the literature are a result of using bundles that are different from each other. We propose that vascular bundles are of 2 types: a parallel pipe type and an axial flap type. We propose that in rats, the femoral arteriovenous bundle represents a parallel pipe type and the epigastric bundle an axial flap type. We propose that if ligated and implanted into an isolated sterile environment, the parallel pipe type of vascular bundle will thrombose, whereas the axial flap type of bundle will remain patent and demonstrate neovascular sprouting., Methods: The study was carried out in 20 rats. Femoral and epigastric bundles were dissected, ligated with 10-0 nylon, and implanted into a tubing of sterile latex. The bundles were analyzed at various time intervals by both gross and histologic examination., Results: The femoral bundle did not demonstrate any arteriovenous cross-communication under magnification, confirming its status as a parallel pipe type. The epigastric bundle demonstrated a rich plexus of arteriovenous channels, confirming its status as an axial flap type. A distinct adherent thrombus was seen at 24 hours in all the ligated femoral bundles and was still present at 3 weeks; none of these demonstrated evidence of neovascular sprouting. The ligated epigastric bundles remained patent in all specimens with no evidence of thrombosis, and all demonstrated exuberant neovascular sprouting., Conclusions: Our experiment establishes that there are at least 2 distinct types of vascular bundles in the rat. It also indicates that parallel pipe type of vascular bundles implanted into latex tubing thrombose and do not demonstrate neovascularization. On the other hand, under the same circumstances axial flap bundles remain patent and demonstrate exuberant neovascularization.

Purpose: To investigate the natural history and visual outcome in eyes with untreated retinal angiomatous proliferation, a neovascular form of age-related macular degeneration., Methods: Fourteen consecutive white patients (11 women, 78%; mean age, 74 years) with 16 eyes affected by retinal angiomatous proliferation were prospectively followed-up without treatment by means of complete ophthalmologic examinations at regular intervals, including best-corrected visual acuity and dynamic fluorescein and indocyanine green angiography using a scanning laser ophthalmoscope., Results: The patients were observed for a mean of 20 months (range, 6-44 months). Mean visual acuity in the eyes with retinal angiomatous proliferation was 0.48 at the initial examination, decreased to 0.23 after 6 months, and was 0.19 at the final examination, with a mean decrease of 6 lines from baseline. In 13 eyes (81%), visual acuity deteriorated by 2 Early Treatment Diabetic Retinopathy Study lines or worse by the time of the 6-month examination, and 31% of the patients had experienced severe loss of vision; the remaining 3 eyes (19%) showed a relatively stable clinical course and visual acuity. By the time of the final examination, visual acuity had decreased to 0.1 or worse in 11 eyes (69%), and 5 of the 14 patients (36%) were legally blind. At the final examination, 10 eyes (62%) showed a subretinal fibrosis and 9 (56%) showed a retinal choroidal anastomosis., Conclusion: Retinal angiomatous proliferation is a distinct form of neovascular age-related macular degeneration with high vasogenic potential, having its own clinical course and visual prognosis. The poor visual outcome is because of the exudative nature of the retinal angiomatous proliferation, and progression to poor vision is common and rapid (within 3 months in faster cases, and within 1 year in slower cases). The treatment options for this type of neovascular lesion should be planned bearing in mind its unfavorable natural history.

Twin-to-twin transfusion syndrome (TTTS) is due to unbalanced inter-twin blood flow through placental vascular anastomoses. We present a TTTS-case treated with fetoscopic laser surgery that allowed us to calculate the net inter-twin blood flow. In the weeks following laser treatment, the ex-recipient developed severe fetal anemia and was treated with two intrauterine adult red cell transfusions (at 26 and 29 weeks' gestation, respectively). After birth, placental injection with color-latex identified a single residual arterio-venous anastomosis from the ex-recipient to the ex-donor. We measured the fetal and adult hemoglobin concentrations in the anemic fetus before and after both intrauterine transfusions, and in both twins at birth. On the basis of these measurements, we calculated the blood flow across the residual arterio-venous anastomosis and found it to be 5.8+/-1.5 mL/24h after the 1st transfusion and 11.4+/-2.9 mL/24h after the 2nd transfusion.