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[A new embolic material: super absorbent polymer (SAP) microsphere and its embolic effects].

SAP-Microsphere (sodium acrylic acid-vinyl alcohol copolymer) has the ability to absorb fluids within a few minutes and increase its diameter. Its diameter can also be calibrated. The diameters in ionic contrast material and human serum are 2.1 and 3.5 times larger, respectively, than the original size. It can pass through a microcatheter with an ionic contrast material, and swells at the occluding point into the desired size. It can be recognized under fluoroscopy due to its absorption of contrast material. A total of 10 rabbit kidney embolizations were done followed by resection in 1-14 weeks. Recanalization was absent in all cases. No adhesion to the perirenal tissue was found. Limited reactive change in endothelial cells was found at one week. No changes in the smooth muscle layer were found at any time during the study. Limited infiltration of neutrophil cells was found in perivascular tissue within a period of one week. SAP-Microspheres maintained their spherical shape during a 14-week period. Extensive fibrosis and calcification were found after 4 weeks. SAP-Microspheres are promising as an embolic agent to obtain satisfactory results of embolization therapy.

Absorption↗

Hepatic embolization through extrahepatic collateral pathways after hepatic arterial embolization for the hepatocellular carcinoma.

Extrahepatic collateral pathways developing after repeated transcatheter arterial embolization (TAE) for hepatocellular carcinoma (HCC) make therapeutic arterial embolization for recurrent lesions extremely difficult. TAE was performed through the collateral pathways using a sophisticated micro-catheter with good trackability and pushability and a coaxial system. Twenty-three TAEs were undertaken through the collateral pathways in 13 patients with recurrent HCC who had extrahepatic collateral pathways after the previous hepatic arterial TAE. There were 69 extrahepatic collateral pathways, with partially obstructed hepatic arteries. On the average, three feeding arteries were seen in the liver. The main extrahepatic collateral pathways were the inferior phrenic artery and epicholedocal artery, 18 vessels and 29 vessels, respectively, accounting for about 80% of the total collateral pathways. TAEs were successful in all cases and the number of embolized vessels was 2.1 on average. The average time of the first collateral TAE after the initial conventional hepatic arterial TAE was 2.3 years. Excellent prognosis was observed with a one-year survival rate of 77% and 3-year survival rate of 38% after the collateral TAE. We consider that collateral TAE for recurrent HCC with obstruction of the hepatic artery is the procedure of choice, is technically feasible, and provides better prognosis for the patients.

Adult↗

Onyx, a new liquid embolic material for peripheral interventions: preliminary experience in aneurysm, pseudoaneurysm, and pulmonary arteriovenous malformation embolization.

PURPOSE: To describe our preliminary experience with a new liquid embolization agent, Onyx, in peripheral interventions. METHODS AND RESULTS: We successfully treated two peripheral aneurysms (one in an internal iliac artery, one in a thoracic collateral artery of an aortic coarctation), two peripheral pseudoaneurysms (one in a lumbar artery, one in a renal artery), and one pulmonary arteriovenous malformation. CONCLUSION: Onyx is a promising alternative embolic material for peripheral interventions. It can be combined with coils in selected cases, and balloon catheters can be effectively used during slow injection of embolic material to control flow and protect the aneurysm neck.

Aged↗

Therapy for unresectable hepatocellular carcinoma: review of the randomized clinical trials-I: hepatic arterial embolization and embolization-based therapies in unresectable hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is common worldwide and frequently fatal. Despite the availability of potentially curative therapies for localized HCC, most patients have unresectable tumor, either at presentation or recurrence. We reviewed 18 randomized trials investigating hepatic arterial embolization-based therapies. Therapy for unresectable HCC is difficult, both because of advanced stage at presentation and accompanying liver dysfunction. Clinical investigations in HCC have been impaired by heterogeneity of enrolled subjects, limited sample sizes and uncertainties regarding optimal mechanisms of delivering therapy. Despite initial reports which suggested limited benefit to hepatic artery embolization-based treatment, more recently published, well-conducted studies demonstrate a survival benefit conferred by hepatic artery chemoembolization. Chemoembolization likely confers a benefit greater than that associated with embolization without chemical agents. There is limited evidence and consensus regarding optimal choice and dosage of chemical agents utilized for hepatic artery chemoembolization.

Antineoplastic Agents↗

A study of embolizing materials for chemo-embolization therapy of hepatocellular carcinoma: antitumor effect of cis-diamminedichloroplatinum(II) albumin microspheres, containing chitin and treated with chitosan on rabbits with VX2 hepatic tumors.

As an effective therapy for hepatocellular carcinoma, hepatic arterial chemo-embolization therapy has been widely used, and many embolizing materials have been extensively investigated. In the present study, we prepared various types of cis-diamminedichloroplatinum(II) (CDDP) albumin microspheres using chitin and chitosan, both of which have attracted considerable attention as new non-toxic biological polymer materials having favorable characteristics such as immune adjuvant activity, biological compatibility, and biodegradation. Hepatic artery of rabbit hepatic cancer models, which had transplanted VX2 tumors, were embolized with various types of microspheres. The anti-tumor effects and tumor-targeting of the microspheres, and the effects of the microspheres administration on the hepatic tissue were investigated. As a result, anti-tumor activity of the microspheres was increased by the addition of chitin-containing or chitosan treated materials; tumor growth rates of chitin addition and chitosan treated groups were approximately 160% and 120%, respectively, and were significantly lower than that of the non-treatment groups with a rate of approximately 580%. However, complete inhibition of tumor growth might have been impossible. Anti-tumor activity was increased by the addition of chitin-containing or chitosan treated materials. Whereas the growth inhibitory effect was insufficient, in order to potentiate anti-tumor activity, higher CDDP contents and sustained release of CDDP at a high level from microsphere and so on should be essentially improved for the near future. The CDDP level in hepatic tissue following the administration of microspheres was increased by adding chitin to the microspheres or by treating the microspheres with chitosan.(ABSTRACT TRUNCATED AT 250 WORDS)

Albumins↗

Embolic cerebral ischemia in carotid surgery: a model for human embolic stroke?

BACKGROUND: If carotid endarterectomy (CEA) is a clinical model of embolic stroke, then it should be possible to determine the relevance of embolus size and of the total quantity of embolic material (embolus load) for ischemic stroke. MATERIAL/METHODS: Thirty-one patients underwent a total of 33 CEAs. Diffusion weighted imaging (DWI) was performed on the day before and after CEA. A new hyperintense signal on the postoperative DWI was considered a new ischemic lesion. Intraoperatively detected microembolic signals (MES) were quantified (in cm) by multiplying embolus velocity by the embolus presence within the Doppler sample volume. With this relative index, emboli were classified into small (<0.56 cm), medium-sized (0.56-1.12 cm) and large (1.12-1.70 cm). RESULTS: For each category of embolus size, embolus load (in cm/minute) was expressed as the sum of all quantified emboli divided by minutes of CEA duration. By logistic regression analysis, the occurrence of a new ischemic lesion was related to an embolus load with medium-sized emboli (without lesion, 0.029 cm/minute; with lesion, 0.157 cm/minute; p=0.018), and with large emboli (without lesion, 0.015; with lesion, 0.055; p=0.038), but not to an embolus load with small emboli or the largest embolus per CEA. CONCLUSIONS: The leading reason for cerebral ischemia in CEA is multiple embolism with emboli of medium and large size. This conceptual model may also apply to carotid artery disease.

Brain Ischemia↗

[Amniotic fluid embolism: successful evolution course after uterine arteries embolization].

A 28-year-old woman, G3P3, who was otherwise healthy and had taken no medication and had no known allergy, was admitted to our hospital for delivery after a normal pregnancy. An epidural catheter was inserted for analgesia and labour was induced with oxytocin. Two hours later, she suffered a sudden cardiac arrest. She was immediately treated and, since a normal cardiac rhythm and a blood pressure of 90 mmHg has been obtained 30 minutes later, a 3750 g child was delivered by caesarean section. Soon after delivery, a life-threatening uterine haemorrhage appeared, due to DIC. Evolution was favourable, after bilateral uterine arteries embolization had been performed. The diagnosis of amniotic fluid embolism was established by the clinical course, the absence of local cause and the presence of a large number of amniotic cells in the mother's peripheral blood. Tryptase blood concentration was normal in the mother's blood.

Adult↗

Pulmonary embolism following embolization of an arteriovenous malformation.

The case of a 12-year-old girl who suffered a severe intracranial bleed secondary to a large arteriovenous malformation (AVM) is described. Following investigation the appropriate treatment was considered to be embolization of the AVM, under general anaesthesia, using N-butyl cyanoacrylate (NBCA). During the procedure acute desaturation and pulmonary oedema occurred secondary to accidental pulmonary embolization with NBCA. The management of the procedure and subsequent clinical course is reported and available literature reviewed.

Anesthesia, General↗

[Cerebral-cardiac embolism. Cerebrovascular-cardiac embolic stroke].

The diagnosis of cerebral cardioembolism requires, apart from evidence of an embolic cardiopathy, a cause-effect relation to be established between the potential cardioembolic source and the occurrence of ischemic stroke. There are several arguments in favour of this reaction, namely the neurologic aspects put forward both clinicians and neuroimaging professionals, as well as the generalization of cardiologic diagnostic techniques for the etiologic investigation of ischemic stroke. Importance should be given to primary prevention of embolic cardiopathies. Oral anticoagulation should be administered in all situations where an advantage has been established when compared to antiaggregation or placebo. Cooperation between the different health structures and the different specialties probably depends on the changes in the prevalence of cerebral cardioembolism.

Embolism↗

The bedside investigation of pulmonary embolism diagnosis study: a double-blind randomized controlled trial comparing combinations of 3 bedside tests vs ventilation-perfusion scan for the initial investigation of suspected pulmonary embolism.

BACKGROUND: We sought to determine whether using combinations of 3 bedside tests (7-variable clinical model, non-enzyme-linked immunosorbent assay D-dimer test, and alveolar dead-space fraction) to exclude pulmonary embolism (PE) before diagnostic imaging was as safe as a standard strategy of starting with ventilation-perfusion (V/Q) scan. METHODS: In this double-blind, randomized, controlled equivalency trial, patients were randomized to initial bedside tests or to initial V/Q scan without bedside tests. Patients assigned to the bedside test group had a sham V/Q scan performed if at least 2 of 3 bedside test results were negative; otherwise, they underwent an actual V/Q scan. Further diagnostic management was determined by a blinded physician after V/Q scan. The primary outcome measure was recurrent venous thromboembolic events during 3 months among patients who were not taking anticoagulant agents after the initial investigations were completed. RESULTS: Four hundred fifty-eight consecutive adults with suspected PE were eligible for the study; 398 of 399 consenting and randomized patients completed the study. The follow-up venous thromboembolic event rate was 2.4% in the bedside test group vs 3.0% in the V/Q scan group (P = .76). Pulmonary embolism was excluded in 34% (67/199) of the bedside test group patients with at least 2 negative results on 3 bedside tests vs 18% (35/199) excluded using only the 7-variable clinical model and the D-dimer test. CONCLUSION: Excluding PE with at least 2 negative results on 3 bedside tests safely eliminates the need for diagnostic imaging in 34% of patients with suspected PE.

Adult↗

Resection of hepatocellular carcinoma after transcatheter arterial embolization. Reevaluation of the advantages and disadvantages of preoperative embolization.

Hepatocellular carcinomas (HCCs) were resected in eight patients who had preoperative transcatheter arterial embolization (TAE) and in 25 patients without preoperative TAE. Three patients in the former group had ruptured HCCs before operation. Two of the former group and three of the latter group were found to have recurrences after a follow-up of 1 1/2 years. Although preoperative TAE resulted in significantly increased tumor necrosis, it increased the risk of gangrenous change of the gallbladder, induced adhesion of the hepatoduodenal ligament, and was not effective in reducing operative blood loss or operative time if the vessel selected for TAE was inadequate. Pathologic examination revealed tumor emboli still existing in the intrahepatic veins. Daughter nodules and capsular invasion by tumor cells were not affected by TAE. Transcatheter arterial embolization seems to be effective in controlling bleeding from ruptured HCC prior to staged resection of the tumor.

Adult↗

Closure of an iatrogenic aortocoronary arteriovenous fistula: transcatheter balloon embolization following failed coil embolization and salvage of coils that migrated into the coronary venous system.

We report a 50-year-old patient with successful percutaneous closure of a large inadvertent surgical aortocoronary arteriovenous fistula (shunt flow: 1.8 L/min). With initial embolization of multiple coils, no lasting occlusion of the large fistula could be achieved. Above that, two coils migrated into the coronary venous system. Following rescue of the migrated coils through a retrograde coronary sinus approach, the fistula was occluded using a detachable balloon. Follow-up angiograms confirmed successful closure of the fistula. In contrast to coil embolization, use of a detachable balloon seems to be the appropriate technique for percutaneous closure of such fistulas.

Arteriovenous Fistula↗

A case of paradoxical embolism "in situ" associated with massive pulmonary embolism: role of echocardiography.

A 49-year-old man was admitted in transfer for further management of a pulmonary embolism (PE) and possible mitral valve vegetation. Transthoracic echocardiography performed at our institution showed evidence of right ventricular (RV) enlargement and dysfunction. Within the right atrium was a serpentine mobile thrombus which traversed the interatrial septum at the level of the fossa ovalis and extended into the left atrium to the level of the anterior mitral valve leaflet. Because of the patient's dyspnea, RV dysfunction, and large clot burden, thrombolytic therapy was considered and would have been administered had the thrombus in situ not been identified. In light of the thrombus in situ and the concern about possible systemic embolization with thrombolytic therapy, the patient underwent successful surgical thrombectomy. This case highlights the importance of echocardiography in the management of patients with PE. We believe that all patients should undergo echocardiography prior to receiving thrombolytic therapy for pulmonary emboli. Careful interrogation of the interatrial septum for the presence of a thrombus in situ is warranted. Thrombectomy should be considered in individuals with PE who have a thrombus in situ.

Coronary Thrombosis↗

Effects of pulmonary gas embolism on circulation and respiration in the dog. V. Effect of changing breathing gas composition on pulmonary gas embolization.

It was found in previous investigations that during venous gas infusion at low rates (1--5 ml/min-1) circulatory and respiratory variables reached a constant level after about 10--15 min. The present study demonstrates that this steady state can be disturbed by changing the composition of the breathing gas mixture. Alteration from air to 21% O2 in helium rapidly increased the embolic effects up to a maximum within 1.5--2 min; in the next 5--8 min the circulatory and respiratory variables returned to their previous levels during air breathing. Reverse effects occurred when changing from 21% O2 in helium to air. Similar phenomena were seen after switching from air to pure oxygen and from 21% O2 helium to pure oxygen. However, the extent of the circulatory and respiratory changes differed depending on the composition of the respective alternating breathing gas mixtures and on the initial embolic level as determined by infusion rate and kind of infusion gas. Gas movements between intravascular bubbles and alveolar space might be responsible for these changes.

Animals↗

Frequent embolization in peripheral angioplasty: detection with an embolism protection device (AngioGuard) and electron microscopy.

PURPOSE: To evaluate the deliverability and protection capabilities of an embolism protection filter in angioplasty of peripheral arteries. METHODS: The Angioguard emboli capture guidewire system was applied in 11 patients with femoropopliteal lesions (6 stenoses, 3 occlusions, 2 controls). Data on lesion crossing, flow deceleration and macroembolization were recorded. Filter membranes were evaluated with scanning electron microscopy (SEM). RESULTS: System delivery was successful in all patients. Primary lesion crossing was feasible in four of six stenoses; predilatation was required in two of six. Marked flow deceleration was recorded in six patients. Emboli next to the filter were detected in each patient with concentric plaques, but could not reliably be removed with the filter. Downstream macroembolization was also present in all patients with concentric stenoses, but in none with chronic occlusion. None of the patients had clinical signs of ischemia. SEM analysis demonstrated only small particles on control group filters and non-obliterating fibrinous conglomerates on filters used in chronic occlusion. Substantial obliteration was seen on several filters used in stenotic lesions. CONCLUSION: Microembolization of fibrin aggregates is a common incident in balloon angioplasty of femoropopliteal stenoses. Macroembolization occurred more frequently than previously reported. The use of embolism protection filters aided in the detection but not in the removal of larger emboli.

Aged↗

Effects of intravenous urokinase versus alteplase on total pulmonary resistance in acute massive pulmonary embolism: a European multicenter double-blind trial. The European Cooperative Study Group for Pulmonary Embolism.

Twelve centers participated in a double-blind study in which 63 patients with angiographically documented acute massive pulmonary embolism were randomly assigned to treatment with either urokinase (4,400 U/kg as an intravenous bolus infusion, then 4,400 U/kg per h over 12 h; n = 29) or alteplase (10 mg as an intravenous bolus infusion, then 90 mg over 2 h) followed by heparin (n = 34). The primary objective was to compare the resolution of pulmonary embolism as judged by the change in total pulmonary resistance over the initial 2 h. Further objectives were to evaluate the changes in total pulmonary resistance over the next 10 h and the degree of angiographic resolution at 12 to 18 h. At 2 h, total pulmonary resistance decreased by 18 +/- 22% in the urokinase group and by 36 +/- 17% in the alteplase group (p = 0.0009). Continuous monitoring of pulmonary artery mean pressure, cardiac index and total pulmonary resistance revealed that these variables improved faster in the alteplase group, with consistently significant intergroup differences from 30 min up to 3 to 4 h. After 12 h, the decrease in total pulmonary resistance was 53 +/- 19% in the urokinase group compared with 48 +/- 17% in the alteplase group and the reduction in the angiographic severity score was 30 +/- 25% compared with 24 +/- 18%, respectively, with no significant intergroup differences. Bleeding was equally frequent in the two treatment groups, except that more urokinase-treated patients experienced hematomas at puncture sites.

Double-Blind Method↗