Unusual cause of acute right ventricular dysfunction: rapid progression of superior vena cava aneurysm complicated by thrombosis and pulmonary thromboembolism

Aneurysms of the major thoracic veins are rare. They are usually asymptomatic and thus treated conservatively. We report an extremely rare case of rapidly progressing superior vena cava (SVC) aneurysm complicated by thrombosis and acute pulmonary thromboembolism (PTE) with right ventricular dysfunction. Thrombolytic therapy for hemodynamically significant acute PTE was harmful to the patient in the present case, because it induced further thrombosis and mobilization of the thrombi within the aneurysm, subsequently causing de novo PTE. Surgical aneurysmectomy combined with pulmonary artery embolectomy would be a treatment of choice in patients with SVC aneurysm complicated by acute PTE.

Hughes-Stovin syndrome

Hughes-Stovin Syndrome (HSS) is a very rare clinical disorder characterized by thrombophlebitis and multiple pulmonary and/or bronchial aneurysms. Less than 40 published cases of HSS have been described in English medical literature so far. The exact etiology and pathogenesis of HSS is unknown; possible causes include infections and angiodysplasia. HSS has also been considered as a variant of Behcet's disease (BD). Patients with HSS usually present with cough, dyspnea, fever, chest pain and haemoptysis. The management of HSS can either be medical or surgical. Medical management includes the use of steroids and cytotoxic agents. Cyclophosphamide, in particular, is a favored therapeutic agent in this regard. Antibiotics have no proven role in HSS while anticoagulants and thombolytic agents are generally contraindicated due to an increased risk of fatal hemorrhage. However, their use may be considered with great care under special circumstances, for instance, intracardiac thrombi or massive pulmonary embolism. For cases of massive hemoptysis due to large pulmonary aneurysms or those with lesions confined to one segment or one lung, lobectomy or pneumectomy can be carried out. However, surgical risks merit serious consideration and must be discussed with the patient. Transcatheter arterial embolization has emerged as a less invasive alternative to surgery in selected cases of HSS. Overall, patients with HSS have a poor prognosis and aneurysmal rupture is the leading cause of death. However, early diagnosis and timely intervention is crucial in improving the prognosis. There is a need to clearly elucidate the genetic, etiologic and pathologic basis for HSS in the future. Although most of the evidence put forward to refute the role of an infectious agent in the etiology and pathogenesis of HSS is based on negative blood and other body fluid cultures, more robust objective assessment is needed through the use of electron microscopy or 16 sRNA studies. The development of better therapeutic agents is also needed to address and prevent the serious consequences arising from pulmonary arterial aneurysms seen in BD and HSS. Also, the issue of anticoagulation in these patients is challenging and requires further deliberation.

MicroRNA-26a is a novel regulator of vascular smooth muscle cell function

Aberrant smooth muscle cell (SMC) plasticity has been implicated in a variety of vascular disorders including atherosclerosis, restenosis, and abdominal aortic aneurysm (AAA) formation. While the pathways governing this process remain unclear, epigenetic regulation by specific microRNAs (miRNAs) has been demonstrated in SMCs. We hypothesized that additional miRNAs might play an important role in determining vascular SMC phenotype. Microarray analysis of miRNAs was performed on human aortic SMCs undergoing phenotypic switching in response to serum withdrawal, and identified 31 significantly regulated entities. We chose the highly conserved candidate miRNA-26a for additional studies. Inhibition of miRNA-26a accelerated SMC differentiation, and also promoted apoptosis, while inhibiting proliferation and migration. Overexpression of miRNA-26a blunted differentiation. As a potential mechanism, we investigated whether miRNA-26a influences TGF-β-pathway signaling. Dual-luciferase reporter assays demonstrated enhanced SMAD signaling with miRNA-26a inhibition, and the opposite effect with miRNA-26a overexpression in transfected human cells. Furthermore, inhibition of miRNA-26a increased gene expression of SMAD-1 and SMAD-4, while overexpression inhibited SMAD-1. MicroRNA-26a was also found to be downregulated in two mouse models of AAA formation (2.5- to 3.8-fold decrease, P < 0.02) in which enhanced switching from contractile to synthetic phenotype occurs. In summary, miRNA-26a promotes vascular SMC proliferation while inhibiting cellular differentiation and apoptosis, and alters TGF-β pathway signaling. MicroRNA-26a represents an important new regulator of SMC biology and a potential therapeutic target in AAA disease.

Open or laparoscopic nephrectomy and extracoroporeal repair of complicated renal artery aneurysms: techniques for renal salvage

Renal artery aneurysm is an infrequently seen disease. The most feared symptom is rupture, which is often rapidly fatal. Indications for intervention include size, intractable symptoms and pregnancy. Many cases are managed by endovascular techniques; however, very complex cases often are referred to the urologist. We report our experience with the rarely used technique of renal artery aneurysms repair comprised of nephrectomy, extracorporeal vascular reconstruction with aneurysmectomy, and autotransplant.

Three-band decomposition analysis of wall shear stress in pulsatile flows

Space-time patterns of wall shear stress (WSS) resulting from the numerical simulation of pulsating hemodynamic flows in semicoronal domains are analyzed, in the case of both regular semicoronal domains and semicoronal domains with bumpy insertions, mimicking aneurysm-like geometries. A new family of cardiovascular risk indicators, which we name three-band diagrams (TBDs), are introduced, as a sensible generalization of the two standard indicators, i.e., the time-averaged WSS and the oscillatory shear index. TBDs provide a handy access to additional information contained in the dynamic structure of the WSS signal as a function of the physiological risk threshold, thereby allowing a quick visual assessment of the risk sensitivity to individual fluctuations of the physiological risk thresholds. Due to its generality, TBD analysis is expected to prove useful for a wide host of applications in science, engineering, and medicine, where risk assessment plays a central role.

Application of one-compartmental bio-metric blood loss calculations with transfused blood volume taken into account after aneurysmectomy

Blood loss can be measured directly and indirectly. The latter reflects blood loss through the assessment of hemoglobin level. Thus aim of this study was to determine the applicability of the drop in hemoglobin levels blood loss calculation when transfused blood volume is taken into account on the patients who underwent aneurysmectomy and to estimate whether this model is applicable on geriatric population. In this study, 14 patients were included and their blood loss was calculated based on hemoglobin concentration. Linear correlation (y = 0.18467 + 1.19315·x) with high correlation coefficient (r = 0.90809) was found between calculated and collected blood loss only if transfused blood volume was taken into account. The coefficient of the regression slope for the blood volume measured during surgery and the calculated blood loss in eight patients ≤65 years (y = 0.90866 + 0.86296·x) and six patients >65 years (y = 0.0299 + 1.32707·x) did not show any significant difference. The applicability of the indirect measurement of surgical blood loss, when transfused blood volume was taken into account, was demonstrated in both populations, in the age of 65 and less and in the age over 65 years after aneurysmectomy.

Optimal filter framework for automated, instantaneous detection of lesions in retinal images

Automated detection of lesions in retinal images is a crucial step towards efficient early detection, or screening, of large at-risk populations. In particular, the detection of microaneurysms, usually the first sign of diabetic retinopathy (DR), and the detection of drusen, the hallmark of age-related macular degeneration (AMD), are of primary importance. In spite of substantial progress made, detection algorithms still produce 1) false positives-target lesions are mixed up with other normal or abnormal structures in the eye, and 2) false negatives-the large variability in the appearance of the lesions causes a subset of these target lesions to be missed. We propose a general framework for detecting and characterizing target lesions almost instantaneously. This framework relies on a feature space automatically derived from a set of reference image samples representing target lesions, including atypical target lesions, and those eye structures that are similar looking but are not target lesions. The reference image samples are obtained either from an expert- or a data-driven approach. Factor analysis is used to derive the filters generating this feature space from reference samples. Previously unseen image samples are then classified in this feature space. We tested this approach by training it to detect microaneurysms. On a set of images from 2739 patients including 67 with referable DR, DR detection area under the receiver-operating characteristic curve (AUC) was comparable (AUC=0.927) to our previously published red lesion detection algorithm (AUC=0.929). We also tested the approach on the detection of AMD, by training it to differentiate drusen from Stargardt's disease lesions, and achieved an AUC=0.850 on a set of 300 manually detected drusen and 300 manually detected flecks. The entire image processing sequence takes less than a second on a standard PC compared to minutes in our previous approach, allowing instantaneous detection. Free-response receiver-operating characteristic analysis showed the superiority of this approach over a framework where false positives and the atypical lesions are not explicitly modeled. A greater performance was achieved by the expert-driven approach for DR detection, where the designer had sound expert knowledge. However, for both problems, a comparable performance was obtained for both expert- and data-driven approaches. This indicates that annotation of a limited number of lesions suffices for building a detection system for any type of lesion in retinal images, if no expert-knowledge is available. We are studying whether the optimal filter framework also generalizes to the detection of any structure in other domains.

Evaluation of the grading performance of an ensemble-based microaneurysm detector

In this paper, results of a diabetic retinopathy screening experiment are presented which is based solely on the findings of a microaneurysm detector. For this purpose, an ensemble-based algorithm developed by our research group was used; this provided promising results in our earlier experiments. At its best, the 1200 image of the Messidor database is classified by this detector with a sensitivity of 96%, a specificity of 51% and achieved an AUC of 0.87. As anticipated, larger microaneurysm counts are recognized with higher level of certainty. Therefore, this approach might be expected to have good performance in relation to the severity of the disease.

Blood flow computation in phase-contrast MRI by minimal paths in anisotropic media

In this paper, anisotropic Fast Marching is employed to compute blood flow trajectories as minimal paths in 3D phase-contrast MRI images. Uncertainty in the estimated blood flow vectors is incorporated in a tensor which is used as metric for the anisotropic Fast Marching. A flow connectivity distribution is computed simultaneously to the Fast Marching. Based on the connectivity distribution the most likely flow trajectories can be identified. Results are presented for several PC MRI data sets and the capability of the method to indicate uncertainty of the flow trajectories is shown.

Dynamic effects on the formation and rupture of aneurysms

Dynamic analysis of an axially stretched arterial wall with collagen fibers distributed in two preferred directions under a suddenly applied constant internal pressure along with the possibility of the formation and rupture of aneurysm are examined within the framework of nonlinear dynamics. A two layer tube model with the fiber-reinforced composite-based incompressible anisotropic hyper-elastic material is employed to model the mechanical behavior of the arterial wall. The maximum amplitudes and the phase diagrams are given by numerical computation of the differential relation. It is shown that the arterial wall undergoes nonlinear periodic oscillation and no aneurysms are formed under the normal condition. However, an aneurysm may be formed under such abnormal conditions as the stiffness of the fibers is deduced or the direction of the fibers is oriented towards the axial direction. Furthermore, the possibility for the rupture of aneurysm is discussed with the distribution of stresses.

Development of a new experimental model of saccular aneurysm by intra-arterial incubation of papain in rabbits

INTRODUCTION

Experimental saccular aneurysms can be created with surgical techniques of the arterial wall or by injecting pancreatic elastase. Papain is an enzyme with properties similar to those of elastase, and it has not been tested for this purpose. The objective of this study was to determine whether papain produces saccular aneurysms.

METHODS

Eleven New Zealand white rabbits (1.9-3.0 kg) were divided into two groups: group I (n = 8)-papain, and group II (n = 3)-sham. The animals underwent surgical exposure of the neck; the right common carotid artery was used as the test and the left common carotid artery as the control. On the 21st day after surgery, animals were sacrificed for removal of the arteries, measurements, and histological analysis. We determine formation of aneurysm to occur when the test artery dilated compared to the control.

RESULTS

There was no aneurysm formation in the sham group. The papain group showed aneurysm formation in all cases (100%). The average diameter of the aneurysms was 3.8  ± 1.4 mm and the average length was 16.7  ±  6.0 mm. The histological analysis showed a destruction of the elastic fibers in 100% of cases, mild inflammation in 62.5%, intimal fibrosis in 50%, endothelial injury in 100%, and thrombosis in 100% of cases.

CONCLUSION

Papain was capable of forming aneurysms with histological characteristics similar to those of elastase-induced aneurysms; however, a comparative study is necessary to determine whether the papain is superior to elastase in the production of experimental saccular aneurysms.

Optimal algorithm for automatic detection of microaneurysms based on receiver operating characteristic curve

Microaneurysms (MAs) are the first manifestations of the diabetic retinopathy (DR) as well as an indicator for its progression. Their automatic detection plays a key role for both mass screening and monitoring and is therefore in the core of any system for computer-assisted diagnosis of DR. The algorithm basically comprises the following stages: candidate detection aiming at extracting the patterns possibly corresponding to MAs based on mathematical morphological black top hat, feature extraction to characterize these candidates, and classification based on support vector machine (SVM), to validate MAs. Feature vector and kernel function of SVM selection is very important to the algorithm. We use the receiver operating characteristic (ROC) curve to evaluate the distinguishing performance of different feature vectors and different kernel functions of SVM. The ROC analysis indicates the quadratic polynomial SVM with a combination of features as the input shows the best discriminating performance.

Gradient estimation revitalized

We investigate the use of a Fourier-domain derivative error kernel to quantify the error incurred while estimating the gradient of a function from scalar point samples on a regular lattice. We use the error kernel to show that gradient reconstruction quality is significantly enhanced merely by shifting the reconstruction kernel to the centers of the principal lattice directions. Additionally, we exploit the algebraic similarities between the scalar and derivative error kernels to design asymptotically optimal gradient estimation filters that can be factored into an infinite impulse response interpolation prefilter and a finite impulse response directional derivative filter. This leads to a significant performance gain both in terms of accuracy and computational efficiency. The interpolation prefilter provides an accurate scalar approximation and can be re-used to cheaply compute directional derivatives on-the-fly without the need to store gradients. We demonstrate the impact of our filters in the context of volume rendering of scalar data sampled on the Cartesian and Body-Centered Cubic lattices. Our results rival those obtained from other competitive gradient estimation methods while incurring no additional computational or storage overhead.

Superior mesenteric artery aneurysm: an uncommon disease with potentially serious complications

Superior mesenteric artery aneurysms (SMAAs) are visceral arterial aneurysms that can result from a variety of conditions. About half of SMAAs are mycotic and occur subsequent to infective endocarditis. The clinical presentation of SMAA is nonspecific, and some patients may be asymptomatic while others may report mild to severe abdominal pain. Herein, we present a case of a 53-year-old man who presented to the emergency department with abdominal pain 5 months after receiving medical treatment for infective endocarditis. CT scan demonstrated an aneurysm in the superior mesenteric artery and a splenic infarct. The patient underwent surgical excision with an uneventful recovery. Although rare, SMAAs are associated with a high risk of death secondary to rupture. They are difficult to detect through physical examination and the history is usually nonspecific. In this report we discuss the etiology of SMAA, diagnostic work-up and treatment options aiming for early diagnosis and management of this potentially fatal condition.

[Three cases of retinal arterial macroaneurysm on the optic disc]

BACKGROUND

Retinal arterial macroaneurysm typically involves the second order arterioles and is relatively uncommon on the optic disc. Here, we present three cases of retinal arterial macroaneurysm.

REPORT OF CASES

Case 1 was a 56-year-old woman, Case 2 was a 78-year-old man, and Case 3 was an 86-year-old man. In Cases 1 and 3, the fundus could not be observed visually at the time of initial examination because of vitreous bleeding. Retinal arterial macroaneurysm was revealed during vitrectomy. In Case 2, retinal arterial macroaneurysm was found on the optical disc along with a retinal hemorrhage which disappeared without any treatment. In all three cases, visual acuity was normal after treatment.

CONCLUSIONS

Since retinal arterial macroaneurysm on the optical disc may be overlooked when treating vitreous bleeding in cases where the cause is not known, we believe that retinal arterial macroaneurysm should be taken into consideration as a possible underlying cause. While photocoagulation of retinal arterial macroaneurysm on the optic disc is infrequently used to, localized photocoagulation retinal arterial macroaneurysm on the optic disk is considered to be difficult. We are of the opinion that progression should be observed carefully till the macroaneurysm is absorbed.

Aneurysm of the petrous portion of the internal carotid artery at the foramen lacerum: anatomic, imaging, and otologic findings

Aneurysms of the petrous portion of the internal carotid artery (ICA) are rare. Their etiology is usually congenital, traumatic, or mycotic. Depending on the size and location of the aneurysm, the direction of its growth, and the specific adjacent structures involved, patients may or may not present with signs and symptoms. When signs and symptoms do manifest, they may include headaches, epistaxis, a vascular retrotympanic mass with hemotympanum and/or otorrhagia, pulsatile tinnitus, hearing loss, vertigo, and Horner syndrome or Raeder paratrigeminal neuralgia. We describe the imaging aspects of the case of a 27-year-old man who presented with a 5-day history of unilateral symptoms secondary to a lesion located in the area of the right foramen lacerum. The lesion proved to be an aneurysm of the petrous portion of the ICA. We discuss the anatomic, imaging, and otologic aspects of ICA aneurysms in this location.

Use of multi-detector computed tomographic angiography in the diagnosis of a parapharyngeal aneurysm in a 6-week-old foal

Multidetector-row computed tomographic contrast angiography (MDCTA) is routinely employed to investigate vascular masses in human patients but, to date, the use of this technique to investigate an aneurysmal mass has not been reported in an equine case. The potential of MDCTA to investigate a right-sided parapharyngeal mass in a 6-week-old Thoroughbred foal was therefore investigated. A 4-slice helical computed tomography scanner was used on a superficial, firm, ovoid mass yielding arterial blood on fine needle aspiration. MDCTA enabled identification of the vessels involved thus assisting in forming a diagnosis based on the morphology of the lesion and aided surgical planning. Histology confirmed the presence of mural thrombus and calcification within the smooth muscle wall consistent with a true aneurysm. MDCTA provided additional information to conventional imaging in this case of vascular masses of the head and neck. The technique therefore has the potential to improve diagnosis and assist in the management of such lesions.

[Angiomatoid fibrous histiocytoma: report of 5 cases with review of literature]

OBJECTIVE

To study the clinicopathologic features, immunophenotype and differential diagnosis of angiomatoid fibrous histiocytoma (AFH).

METHODS

The clinicopathologic features of 5 cases of AFH were analyzed. Immunohistochemical study was carried out and the literature was reviewed.

RESULTS

There were a total of 3 males and 2 females. The average age of patients was 21.4 years old. The average duration of symptoms was 13 months. The patients primarily presented with a slowly enlarging painless deep dermal or subcutaneous mass. The mass was located in the head and neck region in 3 cases, elbow in 1 case and foot in 1 case. The patients underwent complete resection of the tumor, with no adjuvant chemotherapy and/or radiotherapy given. During a period of follow up for 10 to 29 months, all of them had no recurrence or distant metastasis. Gross examination showed that the tumor was well-circumscribed and had a grey-colored cut surface, with focal hemorrhagic cystic changes. The average tumor dimension was 1.9 cm. Histologically, the tumor was composed of histiocytoid or spindly cells arranged in nodular pattern. Fibrillary neuropil-type intercellular material was identified in all cases and a fibrous pseudocapsule surrounded by lymphocytes and plasma cells was demonstrated in 3 cases. Immunohistochemical study showed that all of them were positive for vimentin and negative for S-100 protein, pan-cytokeratin, CD34 and CD31. Three of the cases expressed desmin and CD68. Two cases were epithelial membrane antigen and CD99-positive.

CONCLUSIONS

AFH is a rare tumor of intermediate malignant potential. Definitive diagnosis requires thorough histologic examination and clinical correlation. Immunohistochemistry is also helpful for diagnosis and differential diagnosis. Wide local excision with post-operative follow up is the main modality of treatment.