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PubMed2002

The rehabilitation of clinical assessment for the diagnosis of pulmonary embolism.

Pulmonary angiography is the gold standard for diagnosis of segmental pulmonary embolism, but no longer for subsegmental pulmonary embolism because the inter-observer agreement for angiographically documented subsegmental pulmonary embolism is only 60%. A normal rapid ELISA VIDAS D-dimer test result and a normal perfusion scan exclude pulmonary embolism with a negative predictive value of >99%, irrespective of clinical score. The positive predictive value for pulmonary embolism of a high probability VP-scan compared to pulmonary angiography is 87% indicating that 13% of patients with a high probability VP-scan do not have pulmonary embolism. The combination of a negative CUS, a low clinical score, and a non-diagnostic VP-scan safely excludes pulmonary embolism. Patients with a non-diagnostic VP-scan, a negative CUS, but a moderate to high clinical score are candidates for pulmonary angiography. The positive predictive value of helical spiral CT is >95 to 99%. The combination of a negative CUS, a low clinical score, and the presence of a clear alternative diagnosis is predicted to safely exclude pulmonary embolism. Helical spiral CT detects all clinical relevant pulmonary emboli and a large number of alternative diagnoses in symptomatic patients with a non-diagnostic or a high-probability VP-scan. The negative predictive value during 3 months followup after a negative spiral CT for pulmonary embolism in 4 retrospective studies and 1 prospective management study was >99%. Only a small group of patients (1-2%) with a non-diagnostic spiral CT are candidates for pulmonary angiography. Therefore, it is predicted that the spiral CT will replace both VP-scanning and pulmonary angiography to safely exclude or diagnose pulmonary emboli in patients with suspected pulmonary embolism.

Angiography↗
PubMed2006

[Preoperative and palliative embolization of renal cell carcinomas: follow-up of 49 patients].

PURPOSE: To evaluate the influence of preoperative and palliative embolization of renal cell carcinomas on survival, intra- and post-operative procedures, and symptom control for palliative and preoperative indications. MATERIALS AND METHODS: 56 patients who underwent renal cell carcinoma embolization from 1981 to 1999 were included in this retrospective study. RESULTS: 24 women and 32 men were included (mean age 59.4 years). Complete follow-up data was available for 49 patients. 42 patients underwent preoperative embolization at different tumor stages (pT1: 1 patient, pT2: 6, pT3 a: 4, pT3 b: 19, pT3 c: 2, pT4: 5). 14 patients underwent palliative embolization (T1: 0 patients, T2: 5, T3: 4, T4: 4). Indications for preoperative embolization were bleeding of the renal tumor in 6 cases -- non-recurrent bleeding reported, flank pain in 4 patients -- 3 of 4 patients had no further symptoms, recurrent tumor embolization in 1 patient, and 2 patients who wanted to be treated without symptoms. The mean survival time of preoperative embolized patients was 3.1 +/- 5.11 years with a 5-year survival rate of 50 %. The mean survival time of palliative embolized patients was 0.67 +/- 0.76 years with initial metastases (n = 7) and 2.33 +/- 2.40 without metastases (n = 6). CONCLUSION: Palliative embolization of renal cell carcinomas is a safe therapeutic method to treat advanced renal cell carcinomas allowing control of symptoms such as hematuria and flank pain in more than 90 % of our cases. Preoperative embolization yields a patient survival time comparable to that of patients at earlier tumor stages and is dependent on the metastases.

Angiography↗
PubMedDate not supplied

Prophylactic and emergent arterial catheterization for selective embolization in obstetric hemorrhage.

Treatment of obstetric hemorrhage by the selective embolization of damaged pelvic vessels under fluoroscopy holds promise as an alternative to surgical intervention. Unfortunately, the effectiveness of selective embolization is often compromised by its use in emergent settings following the failure of primary operative approaches. Therefore we compared the efficacy of prophylactic versus emergent catheter placement for selective embolization in nine patients with or at risk for obstetric hemorrhage. In four patients with acute obstetric hemorrhage catheterization and embolization was carried out following the failure of initial medical and surgical approaches. In five patients determined to be at risk for intrapartum hemorrhage based on sonographic findings, catheters were inserted into the hypogastric vessels prior to elective cesarean delivery. Three of these five patients subsequently required selective embolization. In comparison to patients undergoing selective embolization following prophylactic catheter placement, patients in the emergent group all had a coagulopathy at the time of embolization, sustained substantially greater blood loss, and had an increased rate of postpartum complications. Finally, there was a significant reduction in total embolization time and therefore in radiation exposure in patients undergoing prophylactic catheter placement prior to selective embolization. These data support the conclusion that in patients determined to be at risk for intrapartum or postpartum hemorrhage the prophylactic placement of catheters allows for selective embolization in a hemodynamically intact patient with stable coagulation indices, theoretically reducing the risk of maternal morbidity and possibly mortality.

Adult↗
PubMed1998

Role of echocardiography in systemic arterial embolism. A review with recommendations.

The ability of echocardiography to diagnose sources of embolism and the role of the examination in the prediction of thromboembolism are reviewed. In addition, the yield of transthoracic (TTE) and transoesophageal echocardiography (TEE) is analysed in patients with suspected embolism and guidelines are proposed for performing echocardiography in this setting. In general, echocardiography is reliable for diagnosing sources of embolism and this applies in particular to TEE in the case of atrial, valvular, and aortic abnormalities. However, the method is useful for predicting embolism in a few cases only. There is a substantial risk in the event of mobile or protruding thrombi, but screening for these and other markers of thromboembolism seems to be unproductive in most groups of risk patients. Yet, in the presence of atrial fibrillation, echocardiography may be helpful in defining patients with an otherwise normal heart and low risk of embolism--and in defining the relatively rare patient with a clinically low-risk profile but moderate-to-severe left ventricular systolic dysfunction and a high risk of embolism. TEE-guided conversion of atrial fibrillation without weeks of preceding anticoagulation may prove useful, after further investigation. The risk of embolism in relation to the size and mobility of valvular vegetations has remained controversial. In patients with suspected recent embolism, TTE results in less than 5% new therapeutic consequences. In those with a normal TTE, the yield of TEE seems to be equally low. We therefore recommend a selective strategy: TTE and TEE can be omitted when a cardiac source of embolism appears from the clinical setting and in most patients with an obvious predisposition to cerebrovascular disease. However, in the latter cases TTE should be performed if indicated by the clinical situation, e.g. in the presence of fever and murmur. TTE is also recommended when there are no obvious markers of primary vascular disease. To preclude very rare sources of embolism (e.g. atrial thrombi despite sinus rhythm), supplementary TEE is recommended in younger patients in whom primary vascular disease is very unlikely. The diagnosis by TEE of common conditions such as atrial septal aneurysms and patent foramen ovale cannot, however, be taken as proof of the mechanism of a systemic arterial occlusive event; thus it is difficult to change therapy on the basis of such diagnoses.

Algorithms↗
PubMed1998

Doppler estimation of portal blood flow after percutaneous transhepatic portal vein embolization.

OBJECTIVE: To elucidate changes in portal blood flow (PBF) after percutaneous transhepatic portal vein embolization and their possible association with hypertrophy of the nonembolized hepatic segments. SUMMARY BACKGROUND DATA: The increase in PBF of the nonembolized hepatic segments after embolization is presumed to trigger hypertrophy of these segments. However, changes in PBF after embolization have not been investigated, and their extent remains unknown. METHODS: The authors prospectively measured PBF velocity, using color Doppler ultrasound, in 21 patients without cirrhosis who underwent embolization of the right portal vein or the right portal vein plus the left medial portal branch. Liver hypertrophy was assessed with a volumetric study using computed tomography. RESULTS: The PBF velocity significantly increased, from 11.1+/-3.6 cm/sec before embolization to 20.1+/-7 cm/sec 1 day after embolization. Subsequently, the velocity gradually decreased, but it remained significantly elevated until postembolization day 14. The volume of the nonembolized segments significantly increased from 370+/-141 cm3 to 488+/- 145 cm3. The hypertrophy rate (cm3/day) of the nonembolized segments after embolization correlated closely with the extent of increase in the PBF velocity, expressed as the velocity on day 1 divided by the velocity before embolization. The hypertrophy rate had a significant correlation with the absolute value of the PBF velocity on day 1, but its correlation coefficient was low. No significant correlations were observed between the hypertrophy rate and other clinical variables. CONCLUSIONS: The hypertrophy rate of nonembolized hepatic segments after embolization is predictable from the extent of the increase in the PBF velocity. This can be estimated easily and noninvasively with Doppler ultrasound 1 day after embolization.

Adult↗
PubMed1995

Pulmonary artery diastolic-occlusion pressure gradient is increased in acute pulmonary embolism.

OBJECTIVE: To assess the pulmonary artery (PA) diastolic-occlusion (wedge) pressure gradient in patients with acute pulmonary embolism and to evaluate this variable's diagnostic utility. DESIGN: Retrospective, clinical review. SETTING: Intensive care and cardiac catheterization units of a university medical center. INTERVENTIONS: None. PATIENTS: A series of 19 acute pulmonary embolism patients with concurrent right heart catheterization. Control groups consisted of 19 age-, sex-, and heart rate-matched critically ill controls who also underwent right heart catheterization, eight patients suspected of having pulmonary embolism who had negative pulmonary angiography and concurrent right heart catheterization, and 255 patients with a primary diagnosis of coronary artery disease who underwent right heart catheterization at the time of left heart catheterization. MEASUREMENTS AND MAIN RESULTS: Initial hemodynamics (systolic, diastolic, and mean systemic and pulmonary arterial pressures, occlusion pressure, PA diastolic-occlusion pressure gradient, cardiac output, systemic and pulmonary vascular resistances) were compared between cohorts. Other than differences in the PA diastolic-occlusion pressure gradients, no significant differences were identified between cohorts. Pulmonary embolism patients were found to have increased PA diastolic-occlusion pressure gradients (10 +/- 5 vs. 3 +/- 2 mm Hg for the critically ill controls [p < .0002], and 4 +/- 4 mm Hg for the coronary artery disease cohort [p < .0005]). However, no significant difference in PA diastolic-occlusion pressure gradient values was identified when patients with proven pulmonary embolism were compared with patients in whom pulmonary embolism was clinically suspected yet not confirmed by angiograms (10 +/- 9 mm Hg; NS). For three of 19 pulmonary embolism patients, no occlusion pressure could be obtained due to an inability to wedge the balloon tip; 13 of 16 patients had PA diastolic-occlusion pressure gradients of > or = 8 mm Hg. In the pulmonary embolism cohort, PA diastolic-occlusion pressure gradient correlated well with pulmonary vascular resistance (r2 = .50; p < .05), but not with cardiac output or heart rate. CONCLUSION: In the large number of patients with right heart catheters in whom the question of pulmonary embolism is raised, an increased PA diastolic-occlusion pressure gradient (especially > or = 8 mm Hg) may provide a clue to the diagnosis of pulmonary embolism, but is not specific for this diagnosis.

Acute Disease↗
PubMed1997

Arterial embolization is a rapid and effective technique for controlling pelvic fracture hemorrhage.

OBJECTIVE: To review the success rate of embolization in stopping hemorrhage for unstable patients with severe pelvic fractures, to calculate the time to achieve embolization, and to determine the yield from angiography. DESIGN: Retrospective review of patients admitted to a Level I trauma center with pelvic fractures during a 5-year period. MATERIALS AND METHODS: Charts were reviewed for Injury Severity Score, age, blood pressure, prothrombin time/partial thromboplastin time, pelvic fracture type, mortality, time to reach the angiography suite, time to achieve embolization, and mechanism of injury. MEASUREMENTS AND MAIN RESULTS: Of 806 patients admitted with pelvic fractures, 35 underwent pelvic angiography, and 15 (1.9%) required embolization. Embolization was successful for all patients. No deaths resulted from ongoing hemorrhage. Angiography yield in initially unstable patients was 64%. The mean age and initial hemodynamic instability were significantly greater in nonsurvivors. The time from arrival in the trauma bay to arrival in the angiography suite ranged from 50 to 1,140 minutes, and the time spent in the angiography suite performing embolization ranged from 50 to 140 minutes, with an average time of 90 minutes. Patients who were embolized within 3 hours of arrival had a significantly greater survival rate. CONCLUSION: Only a small percentage of patients with pelvic fractures require embolization, but when it is used, embolization can be 100% effective. Age, time to achieve embolization, and initial hemodynamic instability appear to be important factors in survival.

Adolescent↗
PubMed2000

Mortality after successful transcatheter arterial embolization in patients with unstable pelvic fractures: rate of blood transfusion as a predictive factor.

BACKGROUND: To determine the factors predictive of mortality in patients with unstable pelvic fractures after successful transcatheter arterial embolization. METHODS: A retrospective study of pelvic fractures between May of 1995 and April of 1998 was performed. Of 507 patients, 17 who were unstable underwent embolization. The success rate of embolization and the mortality rate after successful embolization were reviewed. Predictive factors (contrast medium extravasation, initial blood pressure, Injury Severity Score, timing of external fixation, time to angiography, volume of blood transfusion, rate of blood transfusion) of the final outcome were statistically analyzed. RESULTS: Embolization was 100% effective in stopping pelvic hemorrhage. The mortality of patients treated successfully with embolization was 17.6%. Among the predictive factors analyzed, only the rate of blood transfusion before embolization, 11.3 +/- 11.0 units/h (death) versus 3.2 +/- 1.9 units/h (survival) showed statistical significance with an odds ratio of 1.62 (95% confidence interval, 1.07-2.46). CONCLUSION: The success rate of embolization was 100% in stopping arterial hemorrhage of unstable pelvic fractures. The survival rate after successful embolization was 82.4%. Patients who had rapid blood transfusion before embolization had a poor final outcome. The risk of dying increased by 62% for every 1 unit/h increase of transfusion rate.

Adolescent↗
PubMed1999

Embolization of rolandic cortex arteriovenous malformations.

OBJECTIVES: To evaluate the safety and efficacy of preradiosurgical and presurgical embolization of arteriovenous malformations (AVMs) involving the rolandic cortex. METHODS: Seventeen consecutive patients with rolandic AVMs seen during a 31-month period (December 1994-July 1997) were evaluated. All patients underwent superselective sodium amobarbital testing to determine any changes in the results of the neurological examinations before undergoing embolization. In 16 of 17 patients (94.1%), somatosensory evoked potentials augmented physical examinations. Patients were embolized with N-butyl cyanoacrylate (Histoacryl; B. Braun, Melsungen, Germany) and iophendylate (Ethiodol; Savage Labs, Melville, NY). Rigid control of the mean arterial pressure (65-75 mm Hg) was maintained in all patients for 24 to 48 hours after embolization. RESULTS: Twenty-three embolization sessions were performed in 17 patients (mean, 1.5 sessions/patient), and a total of 40 feeding arteries were embolized. Two patients were unable to undergo embolization because of positive results of the amobarbital testing despite repeated attempts to reposition a microcatheter in the AVM circulation. In one case, somatosensory evoked potentials and the results of the physical examination were both positive; in the other case, only the somatosensory evoked potentials were used (in a pediatric patient under general anesthesia). All patients with AVMs that were embolized experienced a significant size reduction of their lesions (range, 20-95%; mean, 63%). There were no permanent complications. Four procedures (10% of the procedures, 23% of the patients) resulted in minor transient neurological deficits, with patients' conditions returning to baseline. Thirteen patients subsequently underwent radiosurgery, three underwent surgical resection, and one underwent combined surgery and radiosurgery. Complete obliteration of the lesions has been achieved in four patients to date (three who underwent surgery and one who underwent radiosurgery), with the remainder undergoing further follow-up. CONCLUSION: When properly evaluated before treatment, rolandic AVMs can be embolized with a high success rate (measured by completed embolization and size reduction) and a low complication rate.

Adolescent↗
PubMed1999

Embolization of cerebral arteriovenous malformations with cellulose acetate polymer: a clinical, radiological, and histological study.

OBJECTIVE: A cellulose acetate polymer (CAP) solution was hypothesized to be useful for the embolization of arteriovenous malformations (AVMs). To investigate this possibility, we analyzed the clinical, radiological, and histological results of patients with AVMs embolized by using a CAP solution. METHODS: We reviewed the cases of 11 patients with AVMs treated by embolization before surgical resection. We used two types of CAP solutions, CAP-M and CAP-L, which are mixtures of 250 mg of solid CAP and 1800 or 2250 mg of bismuth trioxide dissolved in 5.5 or 7.0 ml of dimethyl sulfoxide, respectively. After the embolization procedure, percent reduction of the nidus volume was measured, and thereafter, the clinical course and computed tomographic scans and/or magnetic resonance imaging scans were evaluated. All patients underwent surgical resection 1 to 51 days after embolization. Resected specimens were stained for light microscopic examination. RESULTS: Thirty-nine feeding vessels were embolized. The reduction rate of the nidus volume ranged from 20% to nearly 100%. Transient and persistent ischemic deficits occurred in three patients and one patient, respectively, and there were no hemorrhagic complications. All AVMs but one were completely resected by surgery. The embolized AVMs were soft enough to be easily cut and retracted. The histological examinations disclosed no or mild inflammatory reactions within 2 weeks after embolization. The internal elastic lamina was preserved in every case. Recanalization through the cast of the CAP mass was not observed until 51 days after embolization. CONCLUSION: CAP solution is a safe and useful embolic agent for AVMs.

Adult↗
PubMed2000

Effects of a mixture of a low concentration of n-butylcyanoacrylate and ethiodol on tissue reactions and the permanence of arterial occlusion after embolization.

OBJECTIVE: Cyanoacrylates are the most commonly used liquid embolic agents. For embolization of arteriovenous malformations, a mixture of a low concentration of n-butylcyanoacrylate (NBCA) and Ethiodol (Savage Laboratories, Melville, NY) has been recommended for deeper penetration of the nidus. Dilution of NBCA, however, might result in different degrees of tissue reaction and might influence the permanence of vessel occlusion, with an increased risk of vessel recanalization. We compared tissue reactions induced by different NBCA/Ethiodol mixtures and analyzed the permanence of their embolic effects. METHODS: NBCA was diluted with Ethiodol to prepare the following standard solutions: Mixture A, low concentration (NBCA/Ethiodol ratio of 20:80); Mixture B, high concentration (50:50). The study was designed in two parts, because tissue reactions after embolization are considered to be a combination of foreign body reactions to solidified material and reactions to the injured blood vessel. Foreign body reactions were studied by intramuscularly injecting both glue mixtures into the backs of 18 rats. Specimens were obtained at various times after implantation. Immunohistochemical analysis and esterase staining were used to detect macrophages and neutrophils, respectively. The densities of these inflammatory cells were calculated and statistically compared. To study the degree of vascular wall injury and the permanence of embolic effects, the renal arteries in 48 rabbits were embolized with NBCA Mixture A or B. Six specimens for each group were obtained at various times after embolization. RESULTS: There was no significant difference in foreign body reactions between groups treated with Mixtures A and B, at any time. However, the macrophage density was larger for both groups at 3 months versus 3 days and for the group treated with Mixture B at 3 months versus 2 weeks. There was no difference in the degree of vessel wall injury. None of the embolized vessels demonstrated evidence of recanalization. CONCLUSION: The low concentration of NBCA induced a tissue response similar to that of the high-concentration form. Embolized vessels exhibited no greater incidence of recanalization. Therefore, embolization of arteriovenous malformations with diluted NBCA may be safe.

Animals↗
PubMed2003

Validity of index of suspicion for pulmonary embolism after hip arthroplasty.

Pulmonary embolism after total hip arthroplasty is problematic, and intravenous heparin treatment in the absence of pulmonary embolism carries risk. Algorithms for treating pulmonary embolism often cite clinical index of suspicion as a basis for initiating intravenous heparin, but most information regarding variables to predict pulmonary embolism originate from studies of patients rather than only from patients who had arthroplasty. We studied the hypothesis that a more homogenous subpopulation, patients who had total hip arthroplasty, may have findings more accurately predictive of pulmonary embolism. One hundred fifty records of patients who had total hip arthroplasty who were suspected of having pulmonary embolism and who were evaluated for pulmonary embolism were assessed. Complaints, physical findings, heparinization status, and test results were analyzed with univariate and multivariate assessments to determine predictors of pulmonary embolism. No significant differences were found between patients with or without pulmonary embolism regarding subjective complaints, physical examination, blood gas results, electrocardiogram findings, radiographs of the chest, and imaging of the veins of the legs. All attempts to model these variables into an index of suspicion that accurately predicted pulmonary embolism were unsuccessful. We advise adherence to established treatment algorithms rather than clinical suspicion when deciding whether to initiate heparin therapy.

Aged↗
PubMed2005

Comparison of 3 clinical models for predicting the probability of pulmonary embolism.

Two clinical models have been described to predict the probability of pulmonary embolism: the Canadian (or Wells) model, and the Geneva model. A third model has been developed recently at our institution (the Pisa model). We compared the performance of the 3 models in 215 consecutive patients with suspected pulmonary embolism. The clinical probability predicted by the models was categorized as low, intermediate, or high. In all patients, pulmonary angiography was used as the reference diagnostic standard. In patients with pulmonary embolism, the extent of pulmonary embolization was assessed on the lung scan as an index of disease severity. The prevalence of pulmonary embolism was 43.3%, and the median extent of pulmonary embolization at diagnosis was 39.8% (range, 4.5%-75.3%). The proportions of patients categorized as having low, intermediate, or high probability were, respectively: 12%, 60%, and 28%, for the Geneva model; 30%, 55%, and 15%, for the Wells model; 37%, 37%, and 26% for the Pisa model. The frequencies of pulmonary embolism in the low, intermediate, and high probability categories were, respectively: 50%, 39%, and 49% for the Geneva model; 12%, 54%, and 64% for the Wells model; 5%, 42%, and 98% for the Pisa model. Among patients with pulmonary embolism, there was a strong, positive relation between clinical probability predicted by the Pisa model and the extent of pulmonary embolization. The Pisa model proved more accurate than the 2 other models. It may be useful to physicians in defining precisely the pretest probability of pulmonary embolism.

Adolescent↗
PubMed2006

Should pulmonary embolism be suspected in exacerbation of chronic obstructive pulmonary disease?

BACKGROUND: The cause of acute exacerbation of chronic obstructive pulmonary disease (COPD) is often difficult to determine. Pulmonary embolism may be a trigger of acute dyspnoea in patients with COPD. AIM: To determine the prevalence of pulmonary embolism in patients with acute exacerbation of COPD. METHODS: 123 consecutive patients admitted to the emergency departments of two academic teaching hospitals for acute exacerbation of moderate to very severe COPD were included. Pulmonary embolism was investigated in all patients (whether or not clinically suspected) following a standardised algorithm based on d-dimer testing, lower-limb venous ultrasonography and multidetector helical computed tomography scan. RESULTS: Pulmonary embolism was ruled out by a d-dimer value <500 microg/l in 28 (23%) patients and a by negative chest computed tomography scan in 91 (74%). Computed tomography scan showed pulmonary embolism in four patients (3.3%, 95% confidence interval (CI), 1.2% to 8%), including three lobar and one sub-segmental embolisms. The prevalence of pulmonary embolism was 6.2% (n = 3; 95% CI, 2.3% to 16.9%) in the 48 patients who had a clinical suspicion of pulmonary embolism and 1.3% (n = 1; 95% CI, 0.3% to 7.1%) in those not suspected. In two cases with positive computed tomography scan, the venous ultrasonography also showed a proximal deep-vein thrombosis. No other patient was diagnosed with venous thrombosis. CONCLUSIONS: The prevalence of unsuspected pulmonary embolism is very low in patients admitted in the emergency department for an acute exacerbation of their COPD. These results argue against a systematic examination for pulmonary embolism in this population.

Aged↗
PubMed2005

Chitin-based embolic materials in the renal artery of rabbits: pathologic evaluation of an absorbable particulate agent.

PURPOSE: To prospectively evaluate the tissue reaction to and the embolic effect and absorption of chitin and chitosan microspheres and polyvinyl alcohol (PVA) in the renal artery of rabbits. MATERIALS AND METHODS: This experiment was performed in accordance with regulations on animal care and experiments. Thirty-six New Zealand white rabbits were divided into four groups according to the materials (PVA, chitin particles, and chitosan particles, and chitosan microspheres; diameter, 150-250 microm) used for embolization of the right renal artery. A rabbit from each group was sacrificed 1 and 3 days and 1, 2, 4, 8, 16, 24, and 32 weeks after embolization. Gross and microscopic pathologic findings were examined with hematoxylin-eosin, Masson trichrome, and Victoria blue staining. RESULTS: Gross pathologic findings were examined, and swelling of embolized kidneys was observed 1 and 3 days after embolization, whereas shrinkage of the embolized kidneys was consistently seen after 2 weeks, with a hard consistency and nodular surfaces being noted. At histologic analysis, chitosan microspheres filled the lumen more compactly than did other particles. With PVA, a large amount of capillary formations occurred within the embolized arteries, whereas chitin particles and chitosan microspheres showed a lower rate of capillary formation. The shape of all embolic materials remained intact until week 8, at which time the materials gradually decreased in size and number. The chitosan particles and the chitosan microspheres were absorbed around weeks 16 and 24, respectively. CONCLUSION: Chitosan microspheres have great potential as a new embolic material since they block blood vessels more compactly with a lower rate of capillary formation. This material is biocompatible, and it is absorbed 24 weeks after embolization.

Angiography↗
PubMed1998

Life-threatening primary postpartum hemorrhage: treatment with emergency selective arterial embolization.

PURPOSE: To prospectively evaluate the efficacy and safety of emergency selective arterial embolization in the management of intractable primary postpartum hemorrhage. MATERIALS AND METHODS: Twenty-seven consecutively seen women with life-threatening primary postpartum hemorrhage underwent uterine embolization. In all cases, hemostatic embolization was performed because of intractable hemorrhage that could not be controlled with vaginal packing and administration of uterotonic drugs. The mean hemoglobin level before embolization was 7.48 g/dL +/- 2.39 (74.8 g/L +/- 23.9) (1 standard deviation). Hysterectomy performed in two patients before embolization failed to stop the bleeding. RESULTS: Angiography revealed extravasation in nine patients and spasm of the branches of the internal iliac artery in five. The procedure consisted of embolization of uterine (n = 46), vaginal (n = 5), or ovarian (n = 2) arteries or anterior division of internal iliac arteries (n = 8). Immediate disappearance or dramatic diminution of external bleeding was observed in all cases. Two patients needed repeated embolization the next day. No major complication related to embolization was found. In one patient with placenta accreta, delayed hysterectomy was necessary. Normal menstruation resumed in all women except the two who underwent hysterectomy. One woman became pregnant after embolization. CONCLUSION: Emergency arterial embolization is a safe and effective means of control of primary postpartum hemorrhage. The procedure obviates high-risk surgery and allows maintenance of reproductive ability.

Adult↗
PubMed2003

Ebselen, a seleno-organic antioxidant, is neuroprotective after embolic strokes in rabbits: synergism with low-dose tissue plasminogen activator.

BACKGROUND AND PURPOSE: It has been proposed that antioxidants and spin-trap agents may be neuroprotective after acute ischemia stroke. Although the antioxidant ebselen is currently in clinical trials, little is known about the effectiveness of ebselen, which has glutathione peroxidase-like and anti-inflammatory properties in embolic stroke models. Therefore, we determined the effects of ebselen when administered alone or with the thrombolytic tissue plasminogen activator (tPA), the only Food and Drug Administration-approved pharmacological agent for the treatment of stroke. METHODS: Male New Zealand White rabbits were embolized by injection of a suspension of small blood clots into the middle cerebral artery via a catheter. Five minutes after embolization, ebselen (10 to 50 mg/kg) was infused intravenously. Control rabbits received infusions of the vehicle required to solubilize ebselen. In additional rabbits, ebselen (20 mg/kg) was administered 60 minutes after embolization, either alone or in combination with tPA (0.9 or 3.3 mg/kg tPA). Behavioral analysis was conducted 24 hours after embolization, allowing determination of the effective stroke dose (P50) or clot amount (mg) that produces neurological deficits in 50% of the rabbits. RESULTS: A drug is considered neuroprotective if it significantly increases the P50 compared with the vehicle-treated control group. The P50 of controls 24 hours after embolization was 1.35+/-0.30 mg. Rabbits treated 5 minutes after embolization with 10, 20, or 50 mg/kg ebselen had P50 values of 2.12+/-0.56, 2.82+/-0.75 (P<0.05), and 0.49+/-0.54 mg, respectively. A significant neuroprotective effect was observed with the 20-mg/kg dose, but not if there was a 60-minute delay before administration (P50=1.69+/-0.32 mg). When tPA (3.3 mg/kg) was infused 60 minutes after embolization and ebselen (20 mg/kg) was injected at either 5 (P50=2.98+/-0.18 mg) or 60 (P50=3.60+/-0.79 mg) minutes, there was no additional neuroprotective effect compared with tPA alone (P50=3.38+/-0.55 mg). However, if ebselen (20 mg/kg) was administered concomitantly with low-dose tPA (0.9 mg/kg) 60 minutes after embolization, the P50 was 3.52+/-0.73 mg (P<0.05), indicating a synergistic effect of the drug combination because neither alone was effective (P50=1.69+/-0.32 and 1.54+/-0.36 mg, respectively). CONCLUSIONS: This study indicates that ebselen may be neuroprotective when administered shortly after an embolic stroke, but the time- and dose-response analyses suggest that it has a narrow therapeutic window. Nevertheless, ebselen may be beneficial if administered concomitantly with a thrombolytic because it significantly enhanced the neuroprotective activity of low-dose tPA.

Animals↗
PubMed2000

Evaluation of new online automated embolic signal detection algorithm, including comparison with panel of international experts.

BACKGROUND AND PURPOSE: The clinical application of Doppler detection of circulating cerebral emboli will depend on a reliable automated system of embolic signal detection; such a system is not currently available. Previous studies have shown that frequency filtering increases the ratio of embolic signal to background signal intensity and that the incorporation of such an approach into an offline automated detection system markedly improved performance. In this study, we evaluated an online version of the system. In a single-center study, we compared its performance with that of a human expert on data from 2 clinical situations, carotid stenosis and the period immediately after carotid endarterectomy. Because the human expert is currently the "gold standard" for embolic signal detection, we also compared the performance of the system with an international panel of human experts in a multicenter study. METHODS: In the single-center evaluation, the performance of the software was tested against that of a human expert on 20 hours of data from 21 patients with carotid stenosis and 18 hours of data from 9 patients that was recorded after carotid endarterectomy. For the multicenter evaluation, a separate 2-hour data set, recorded from 5 patients after carotid endarterectomy, was analyzed by 6 different human experts using the same equipment and by the software. Agreement was assessed by determining the probability of agreement. RESULTS: In the 20 hours of carotid stenosis data, there were 140 embolic signals with an intensity of > or =7 dB. With the software set at a confidence threshold of 60%, a sensitivity of 85.7% and a specificity of 88.9% for detection of embolic signals were obtained. At higher confidence thresholds, a specificity >95% could be obtained, but this was at the expense of a lower sensitivity. In the 18 hours of post-carotid endarterectomy data, there were 411 embolic signals of > or =7-dB intensity. When the same confidence threshold was used, a sensitivity of 95.4% and a specificity of 97.5% were obtained. In the multicenter evaluation, a total of 127 events were recorded as embolic signals by at least 1 center. The total number of embolic signals detected by the 6 different centers was 84, 93, 108, 92, 63, and 78. The software set at a confidence threshold of 60% detected 90 events as embolic signals. The mean probability of agreement, including all human experts and the software, was 0.83, and this was higher than that for 2 human experts and lower than that for 4 human experts. The mean values for the 6 human observers were averaged to give P=0.84, which was similar to that of the software. CONCLUSIONS: By using the frequency specificity of the intensity increase occurring with embolic signals, we have developed an automated detection system with a much improved sensitivity. Its performance was equal to that of some human experts and only slightly below the mean performance of a panel of human experts

Algorithms↗