The pathology of encephalic arteriovenous malformations treated by prior embolotherapy

Summary A pathologic study was undertaken of seven encephalic arteriovenous malformations, including five resected from one to seven days after balloon embolization, one resected 10 days after embolization with polyvinyl alcohol foam (PVA), and a large mesencephalic AVM in a patient who died eight weeks after a series of embolization procedures with PVA and silicone spheres. AVM's resected 6–7 days following balloon embolization showed focal mural and adventitial inflammatory infiltrates and parenchymal (i.e. non-vascular) necrosis of a large portion of one AVM. The AVM examined 7 days post-balloon embolization showed an intraluminal thrombus containing refractile particles surrounded by foreign body giant cells (FBGC's). The AVM removed 10 days after PVA embolotherapy showed mural and perivascular necrosis with infiltration by polymorphonuclear leukocytes. The single autopsy case showed FBGC's surrounding residual PVA, refractile particles deep within vascular walls, and marked mural thickening of AVM channel walls, changes that may represent a response to previous angionecrosis and inflammation at the time of embolization. These findings, the pathogenesis of which is discussed in detail, may help to explain some of the rare complications of iatrogenic embolotherapy with these materials, as well as providing evidence for the basis of their efficacy.Presented in part at the 63rd Annual meeting of the American Association of Neuropathologists, Seattle, Washington, June, 1987     

Influence of Agonist, Shear Rate, and Perfusion Time on Nitric Oxide Inhibition of Platelet Deposition

Nitric oxide (NO) is a physiological species involved in inhibition of platelet adhesion and aggregation. A novel NO delivery device was utilized to quantitatively assess the effects of gaseous NO on platelet deposition to agonist-coated biomaterials in the presence of a platelet suspension. Platelet deposition was evaluated as a function of agonist (collagen, fibrinogen, or IgG), shear rate (250, 500, and 750 s^–1), and perfusion time (5, 7.5, and 15 min). The minimal aqueous surface NO concentrations and fluxes necessary for significant inhibition of platelet deposition were quantified. Platelet deposition was completely inhibited at a gaseous NO exposure of 0.1 ppm, irrespective of the platelet agonist, shear rate, and perfusion time. The corresponding aqueous surface NO concentration was 0.09 nM at 250 s^–1 as predicted by a validated model. Surface fluxes ranged between 0.3 and 0.6 femtomoles cm^–2 s^–1. The results of this study are useful for establishing generalized guidelines (i.e., NO flux requirements in the presence of agonists, shear rate, and perfusion time) for the design and development of suitable biomaterials incorporating NO to reduce platelet deposition. Further studies incorporating blood, rather than platelet suspensions, are required to provide a more complete assessment of the required NO flux necessary to inhibit platelet deposition. © 2000 Biomedical Engineering Society. PAC00: 8717-d, 8719Tt     

Microembolization from a carotid mural thrombus detected by transcranial Doppler

Over the last few years, many authors have described the possibility of using transcranial Doppler to demonstrate the passage of microemboli in the cerebral arteries. We report the case of a 44-year-old woman with thrombotic diathesis and thrombocytosis who was admitted twice within a short period of time (one and a half months) to a neurological department because of multiple cerebral infarctions. On the occasion of the second admission, a colour-Doppler examination of the epiaortic vessels, which had previously been negative, showed a carotid lesion due to a mural thrombus and, on the same side as the carotid lesion, transcranial Doppler detected short-duration, high-intensity signals in the middle and anterior cerebral arteries, an expression of the passage of microemboli.As already described by other authors in similar clinical situations, our case confirms that transcranial Doppler can identify the passage of microemboli in the circle of Willis.

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Sommario Negli ultimi anni è stata descritta da molti autori la possibilità di dimostrare mediante Doppler transcranico il passaggio di microemboli nelle arterie cerebrali. Riportiamo il caso di una donna di 44 anni con diatesi trombotica e trombocitosi ricoverata per due volte, a breve distanza di tempo (un mese e mezzo), in ambiente neurologico per infarti cerebrali multipli. In occasione del secondo ricovero l'esame Color-Doppler dei vasi epiaortici, che era risultato negativo in precedenza, ha evidenziato una lesione carotidea riferibile a un trombo murale e al Doppler transcranico sono stati rilevati, omolateralmente alla lesione carotidea, segnali di breve durata ed alta intensità nelle arterie cerebrali media e anteriore, espressione di passaggio di microemboli.Come già descritto da alcuni autori in situazioni cliniche simili, il nostro caso conferma la possibilità di individuare, mediante Doppler transcranico, il passaggio di microemboli nel circolo cerebrale.

     

浅述肺动脉栓塞栓子来源

肺栓塞是临床常见的高病死率疾病，其起病急骤、进展迅速，是世界范围内主要的健康问题。肺栓塞栓子来源多样、发病机制复杂，不同栓子类型的肺栓塞其发病机制不尽相同，尤其是非血栓性肺栓塞较血栓性肺栓塞少见，在临床工作中容易漏诊、误诊，其发病机制尚不明确，除机械性阻塞外，可能还与栓子性质有关，这为临床医师及时明确诊断带来困难。本文现就肺栓塞各栓子来源及病理生理进行简要综述，旨在为临床医师对肺栓塞的早期预防及肺栓塞病因分析提供一定参考。     

A dumbbell thrombus entrapped in patent foramen ovale

A 75-year-old lady came to emergency room due to dizziness andpresyncopal attacks during exertion since two days prior toadmission. Transesophageal echocardiography revealed a thrombuslike mass in right atrium traversing patent foramen ovale andextending to left atrium. Spiral chest CT scan showed bilateralpulmonary thromboemboli. Operative and pathological findingsconfirmed the diagnosis.     

Cholesterol masses in association with spinal cord infarction due to intervertebral disc emboli

Summary The clinical and autopsy findings are presented from three dogs with spinal cord infarction. At autopsy firm gritty masses and cystic areas were present within the spinal cord. The masses contained numerous cholesterol clefts, collagen and reticulin fibres and were accompanied by a macrophage, giant cell and lymphocytic reponse. The cholesterol masses were present mainly in white matter. The ventral spinal artery or its branches as well as pial arteries contained fibrillary masses often covered by endothelial cells. The staining characteristics of these emboli suggested that they were fibro-cartilagenous and probably derived from the intervertebral discs. It is assumed that the cholesterol masses were formed from myelin breakdown products within infarcted areas.     

Fettembolie in der Milz

Zusammenfassung Fettembolie der Milz kommt relativ selten vor. Die Fettemboli liegen dabei einmal in den Zentralarterien und in deren Kapillaren im Bereich der Malpighischen Körperchen, dann wiederum in der roten Pulpa in arteriellen Kapillaren oder in den Sinus. Ein Teil der Fettropfen wird von monozytären Elementen aufgenommen. Das ist besonders dann zu beobachten, wenn der Verletzte einige Tage nach dem Trauma mit Beginn der Fettembolie im großen Kreislauf verstirbt. Ursache für das beschriebene Verteilungsmuster der Fetttropfen in der Milz sind offenbar Besonderheiten an der Strombahn der Milz in Form der Hülsenkapillaren, die aus den Pinselarteriolen hervorgehen und wahrscheinlich in diesem Abschnitt der Strombahn den Übertritt von Fettbestandteilen aus der Blutbahn ins Gewebe unmöglich machen.     

Prevalence of left atrial appendage pseudothrombus filling defects in patients with atrial fibrillation undergoing coronary computed tomography angiography

Background

Previous reports have shown that computed tomography (CT) is a useful, noninvasive test for detecting atrial thrombi. However, blood stasis in the left atrial appendage (LAA) of patients with atrial fibrillation (AF) may be a common cause for false-positive results.

Objectives

We retrospectively evaluated the prevalence of filling defects that may simulate thrombus in the LAA of patients with AF during routine coronary CT angiography (CTA).

Methods

The LAA of 7 patients with AF was studied for the presence of filling defects and compared with 250 healthy persons. LAA volume in the patients with AF was measured at 10 different cardiac phases and compared with 30 healthy patients.

Results

Of the 7 patients with AF studied with CTA, 5 were positive for LAA filling defects. Follow-up imaging studies, including transesophageal echocardiogram, contrast-enhanced magnetic resonance angiography, or delayed-CT, were negative for LAA thrombus. Of 250 patients without AF, CTA showed no evidence of LAA filling defects. Patients with AF had significantly larger LAA volumes at all cardiac phases measured compared with patients without AF (15.2 ± 6.93 mL compared with 6.85 ± 3.01 mL at atrial contraction [P = 0.0187], 17.4 ± 7.76 mL compared with 9.46 ± 3.43 mL at ventricular systole [P = 0.0351], and 14.5 ± 5.87 mL compared with 8.48 ± 3.10 mL at mid-diastole [P = 0.0341]). Compared with the healthy persons, the patients with AF showed reduced percentages of change in LAA volume when the atrial contraction phase was compared with other phases: 44.0% ± 25.6% compared with 16.5% ± 12.2% compared with ventricular systole (P = 0.0004) and 29.5% ± 23.7% compared with −1.63% ± 8.84% at mid-diastole (P < 0.0001).

Conclusions

Pseudothrombus filling defects are common in the LAA of patients with AF undergoing coronary CTA and should not be mistaken for real thrombus.     

Treatment of Branch Retinal Artery Occlusion With Transluminal Nd:YAG Laser Embolysis

The purpose of this paper was to report a successful treatment of transluminal Nd:YAG laser embolysis (NYE) for branch retinal artery occlusion (BRAO) with visible emboli. Two patients with acute, severe vision loss secondary to a branch retinal artery occlusion with visible emboli in one eye underwent NYE. A complete ocular examination was performed which included biomicroscopy of the posterior pole of the retina, intraocular pressure measurement, fundus color photographs, and fluorescein angiography (FA). After the NYE, the two patients showed dramatic improvements in best-corrected visual acuity, as well as, immediate and dramatic restorations in flow past the obstructed arteriole in FA. NYE is a treatment modality to be considered in patients with BRAO who present acutely with severe vision loss and a visible embolus.