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PubMed1992

Reduction of infarct volume and mortality by thrombolysis in a rat embolic stroke model.

BACKGROUND AND PURPOSE: Thrombolytic therapy with recombinant tissue plasminogen activator was tested in a rat embolic stroke model. METHODS: The rat carotid territory was embolized with arterial-like microthrombi formed under pressure. Hemispheric cerebral blood flow before and after embolization was measured by the intraarterial Xenon-133 injection method. Fifteen minutes after embolization, 24 rats were treated with 3 mg/kg or 10 mg/kg tissue plasminogen activator, and 27 were treated with saline. Carotid angiography displayed the rate of occlusion of the cerebral arterial supply before and after treatment. Brains were fixed and evaluated neuropathologically and infarct volume was measured. RESULTS: Cerebral blood flow was reduced 70-86% after embolization. The comparison of pretreatment and posttreatment angiography showed significant (p = 0.0005) reperfusion in the treated rats. Thrombolytic therapy significantly reduced the infarct volume from 55.1% to 24.4% of embolized hemisphere volume (p = 0.007) and increased the survival rate from 0.48 to 0.96 (p = 0.0004). Fifty-three percent of the embolized rats recanalized completely after thrombolytic treatment and developed almost no infarction (median volume 2.8%), and all survived. No hemorrhagic complications were observed. CONCLUSIONS: Early thrombolytic therapy induced recanalization and reduced mortality and infarct volume after embolic stroke in this model.

Animals↗
PubMed1994

The effect of velocity on the appearance of embolic signals studied in transcranial Doppler models.

BACKGROUND AND PURPOSE: Transcranial Doppler ultrasound can be used to detect circulating cerebral emboli. Recent studies have demonstrated that embolus size is significantly related to both the relative intensity increase and duration of an embolic signal. This may allow information about embolus size to be obtained by analysis of Doppler embolic signals. However, theoretically duration will be inversely related to velocity, and therefore velocity may need to be accounted for if information on embolus size is to be derived from the duration of Doppler embolic signals. METHODS: The relation between velocity and both relative intensity increase and duration of embolic signal was investigated in an in vitro flow model, a sheep carotid artery model, and in patients with prosthetic heart valves. The same standard transcranial Doppler ultrasound machine was used for all studies. Embolic signals resulting from 99 glass microspheres (size, 210 to 250 microns) were studied in the in vitro model, as were those from 64 glass microspheres (size, 105 to 150 microns) in the sheep model. Embolic signals recorded from the six middle cerebral arteries of three patients with prosthetic cardiac valves were also studied. RESULTS: There was a significant (P < .001) inverse relation between velocity and duration of high-intensity signal (in vitro model, r = -.82; sheep model, r = -.43); the exact relations were described using best-fit equations. Correlation coefficients for this relation in patients varied between -.30 and -.55. There was also an unexpected significant positive relation between velocity and intensity in the sheep model (r = .44, P < .001) but not in the in vitro model (P > .05). This relation was also seen in some, but not all, patients. CONCLUSIONS: When the duration of embolic signals is used to provide information about the relative size of an embolus, the velocity of the embolic signal should be taken into account. A relation between velocity and relative intensity increase was found in the sheep model and in some patient recordings. It is suggested this relation may result from greater power being supplied to emboli traveling at higher velocities in the center of the vessel; this may occur under certain recording conditions.

Animals↗
PubMed1967

Physiologic studies of the pulmonary capillary bed after barium sulfate embolization.

22 anesthetized dogs were given a barium sulfate suspension intravenously in a dose sufficient to double mean pulmonary artery pressure. 10 sec breath-holding carbon monoxide diffusing capacity (D(LCO10)) was measured before and after this standard embolization in each dog. No post-embolic decrease in D(LCO10) was observed. In the study of this apparent paradox, it was found that the potential for further increase in D(LCO10) during exercise remained after embolization. During rest prolongation of breath holding to 60 sec decreased CO absorption significantly more in the embolized than in the nonembolized dogs. While D(LCO10) was not affected by standard barium embolization, oxygen diffusing capacity was clearly decreased. The bronchial collateral circulation did not participate in preventing a D(LCO10) decrease after embolization since surgical interruption of the bronchial circulation did not alter the response to barium. Microscopic examination of lung sections taken after standard embolization showed plugging of precapillary vessels in the 40-50 mu range. These studies suggest that acute precapillary embolic obstruction of vessels of this size interferes remarkably little with CO absorption over short periods of time, probably because of continued CO absorption in portions of the capillary net distal to the sites of impaction. The remarkable anastomotic nature of this capillary network with multiple sources of access possibly provides the anatomic basis for this observation. This study demonstrates a clear dissociation between acute changes in pulmonary vascular resistance and D(LCO10)-both during rest and exercise.

Animals↗
PubMed2004

Fractionated stereotactic radiotherapy for the treatment of large arteriovenous malformations with or without previous partial embolization.

OBJECTIVE: Despite the success of stereotactic radiosurgery, large inoperable arteriovenous malformations (AVMs) of 14 cm(3) or more have remained largely refractory to stereotactic radiosurgery, with much lower obliteration rates. We review treatment of large AVMs either previously untreated or partially obliterated by embolization with fractionated stereotactic radiotherapy (FSR) regimens using a dedicated linear accelerator (LINAC). METHODS: Before treatment, all patients were discussed at a multidisciplinary radiosurgery board and found to be suitable for FSR. All patients were evaluated for pre-embolization. Those who had feeding pedicles amenable to glue embolization were treated. LINAC technique involved acquisition of a stereotactic angiogram in a relocatable frame that was also used for head localization during treatment. The FSR technique involved the use of six 7-Gy fractions delivered on alternate days over a 2-week period, and this was subsequently dropped to 5-Gy fractions after late complications in one of seven patients treated with 7-Gy fractions. Treatments were based exclusively on digitized biplanar stereotactic angiographic data. We used a Varian 600SR LINAC (Varian Medical Systems, Inc., Palo Alto, CA) and XKnife treatment planning software (Radionics, Inc., Burlington, MA). In most cases, one isocenter was used, and conformality was established by non-coplanar arc beam shaping and differential beam weighting. RESULTS: Thirty patients with large AVMs were treated between January 1995 and August 1998. Seven patients were treated with 42-Gy/7-Gy fractions, with one patient lost to follow-up and the remaining six with previous partial embolization. Twenty-three patients were treated with 30-Gy/5-Gy fractions, with two patients lost to follow-up and three who died as a result of unrelated causes. Of 18 evaluable patients, 8 had previous partial embolization. Mean AVM volumes at FSR treatment were 23.8 and 14.5 cm(3), respectively, for the 42-Gy/7-Gy fraction and 30-Gy/5-Gy fraction groups. After embolization, 18 patients still had AVM niduses of 14 cm(3) or more: 6 in the 7-Gy cohort and 12 in the 5-Gy cohort. For patients with at least 5-year follow-up, angiographically documented AVM obliteration rates were 83% for the 42-Gy/7-Gy fraction group, with a mean latency of 108 weeks (5 of 6 evaluable patients), and 22% for the 30-Gy/5-Gy fraction group, with an average latency of 191 weeks (4 of 18 evaluable patients) (P = 0.018). For AVMs that remained at 14 cm(3) or more after embolization (5 of 6 patients), the obliteration rate remained 80% (4 of 5 patients) for the 7-Gy cohort and dropped to 9% for the 5-Gy cohort. A cumulative hazard plot revealed a 7.2-fold greater likelihood of obliteration with the 42-Gy/7-Gy fraction protocol (P = 0.0001), which increased to a 17-fold greater likelihood for postembolization AVMs of 14 cm(3) or more (P = 0.003). CONCLUSION: FSR achieves obliteration for AVMs at a threshold dose, including large residual niduses after embolization. With significant treatment-related morbidities, further investigation warrants a need for better three-dimensional target definition with higher dose conformality.

Adult↗
PubMed1991

Pulmonary embolism. Efficacy of D-dimer and thrombin-antithrombin III complex determinations as screening tests before lung scanning.

The aim of the study was to evaluate if D-dimer and thrombin-antithrombin III complex determinations in patients with clinically suspected pulmonary embolism create a discrimination between patients to be further investigated with lung scanning and those who should be investigated for other diseases mimicking pulmonary embolism. The Data-Fi Dimertest Latex Assay, MAbCO Dimertest EIA, and TAT EIA were performed in 100 consecutive patients (26 percent outpatients) who were sent to our institution for lung scanning by their attending physicians because of clinically suspected pulmonary embolism. The D-dimer Latex Assay was positive (greater than 500 ng/ml) in 12 (48.0 percent) of 25 patients with high probability of pulmonary embolism and in one (11.1 percent) of nine with intermediate probability, respectively. Only one patient (1.5 percent) with a normal scan had a positive latex assay, presumably due to inapparent bleeding after a computed tomographic (CT)-guided liver biopsy. Referring to 120 ng/ml as upper limit of normal (mean +/- 2 SD of healthy controls), the D-dimer enzyme immunoassay (EIA) was positive in 21 (84.0 percent) of 25 patients with high probability, in six (66.7 percent) of nine patients with intermediate probability, and in 40 (60.6 percent) of 66 patients with normal/low probability of pulmonary embolism, respectively. The TAT EIA was positive (greater than mean +/- 2 SD of healthy controls = 3.53 ng/ml) in 18 (72.0 percent) of 25 patients with high probability, in five (55.6 percent) of nine patients with intermediate probability and in 16 (24.2 percent) of 66 patients with normal/low probability of pulmonary embolism. A normal result in one of these hemostaseologic tests did not predict a low probability of pulmonary embolism after lung scanning. Thus, it is not justified to exclude patients with clinically suspected pulmonary embolism from further investigation by lung scanning because of a normal result in one of these tests.

Adult↗
PubMed1995

Anticoagulation in the prevention and treatment of pulmonary embolism.

The anticoagulant agents commonly used in prevention and treatment of pulmonary embolism are unfractionated heparin, and more recently, low molecular weight heparins, and oral anticoagulants. Unfractionated heparin is the drug of choice for prophylaxis and short-term treatment of pulmonary embolism. Oral anticoagulants are used for prophylaxis in high risk patients and in long-term treatment of pulmonary embolism. Independent overview analysis of clinical trials in elective surgery showed a 60 to 70% reduction in the incidence of fatal pulmonary embolism in heparin-treated patients when they were compared with placebo-treated patients. Low dose heparin has also been shown to be effective in reducing venous thromboembolism after myocardial infarction and other serious medical disorders. In high risk patients prophylaxis with low molecular weight heparins or adjusted doses of unfractionated heparin is recommended. The objectives of treating patients with pulmonary embolism are to prevent death, to reduce morbidity from the acute event, and to prevent thromboembolic pulmonary hypertension. These objectives are achieved by the administration of heparin followed by oral anticoagulants. Heparin is generally administered for 7 to 10 days and is followed by oral anticoagulants. Although widely used and effective in the prevention and treatment of pulmonary embolism, unfractionated heparin has some pharmacological limitations. Heparin presents an aspecific "nonfunctional" binding to plasma proteins such as fibrinogen, factor VIII, vitronectin, and fibronectin. This aspecific binding limits the anticoagulant effect of unfractionated heparin and, is responsible for the heparin resistance observed in some patients with pulmonary embolism as well as of the high intersubject variability of the heparin-induced anticoagulant effect. Antithrombotic agents, such as low molecular weight heparins and pure thrombin inhibitors (hirudin and its analogues), do not specifically bind to plasma protein and they will probably improve the efficacy and practicality of the treatment of pulmonary embolism.

Anticoagulants↗
PubMed1989

Recurrent pulmonary embolism. A prospective study.

We have prospectively studied a series of 121 consecutive patients with venous thromboembolism (38 with pulmonary embolism, 83 with venous thrombosis of the lower extremities) searching for recurrences of pulmonary embolism despite adequate heparin therapy. A baseline ventilation-perfusion lung scan was obtained initially in every patient, whether the original diagnosis was pulmonary embolism or venous thrombosis. Repeat chest roentgenograms and lung scans were obtained routinely at eight days of heparin treatment. The primary trial endpoints were a finding of a clinically apparent recurrent pulmonary embolism, or laboratory evidence of subclinical pulmonary embolism. Eight items of clinical and laboratory information were recorded at admission and then correlated with the lung scan results. Recurrences were seen in seven of 38 patients with an original diagnosis of pulmonary embolism, and in five of 83 patients admitted because of venous thrombosis (p = 0.034). Recurrences were also more frequent in patients with a free-floating thrombus on venography (p = 0.014). The risk of new defects in patients with venous thrombosis and without free-floating thrombus was 3.05 percent, venous thrombosis with free-floating thrombus, 13.33 percent; patients with pulmonary embolism without free-floating thrombus, 11.42 percent; and with free-floating thrombus, 38.67 percent. Venography seems thus mandatory in patients with pulmonary embolism, as it recognizes a subgroup of patients at a high risk of recurrences.

Adult↗
PubMed1991

Acute pulmonary embolism triggered by the act of defecation.

Pulmonary embolism associated with the act of defecation has not been previously well described. Recently, we reported our experience with four patients who presented to us over a 12-month period with syncope, near syncope, or sudden death following the act of defecation. In all four cases, acute pulmonary embolism was shown to be the etiology of the defecation-associated events. A retrospective chart review of all patients with the diagnosis of pulmonary embolism at our institution over a three-year period yielded five additional patients with the diagnosis of defecation-associated pulmonary embolism. These nine patients accounted for 6.8 percent of all patients with a discharge diagnosis of pulmonary embolism seen at our institution during the three-year study period. Six of the nine patients died from their defecation-associated pulmonary embolism. These six deaths accounted for 25 percent of all deaths from pulmonary embolism seen at our institution during the study period. Based on our experience, we suggest that the act of defecation may trigger the development of acute pulmonary embolism in some patients with deep vein thrombosis.

Acute Disease↗
PubMed2005

Embolic activity subsequent to injection of the internal mammary artery with papaverine hydrochloride.

BACKGROUND: Neurologic injury is a rare yet devastating outcome of coronary artery bypass grafting surgery. Mechanisms producing both focal and global neurologic injuries include embolization, cerebral hypoperfusion, and hypotension. In this present study, we report an association between variations in the treatment of the internal mammary artery with the detection of cerebral embolic signals. METHODS: An intensive intraoperative neurologic and physiologic monitoring approach was implemented to associate discrete processes of clinical care with the concurrent detection of cerebral embolic signals, cerebral hypoperfusion, and hypotension. The method of treating the left internal mammary artery was tracked among 68 patients undergoing isolated coronary artery bypass grafting. Cerebral embolic signals were counted within 3 minutes of the treatment of the left internal mammary artery. RESULTS: Among a series of 68 patients undergoing isolated coronary artery bypass grafting, 22 were not treated with papaverine. Of those treated, 12 received injection intraluminally and 28 had a topical application. Embolic signals were noted concurrently among 7 patients receiving injection of papaverine. No embolic signals were noted among patients who were treated topically. CONCLUSIONS: We report an association between the injection of papaverine hydrochloride and cerebral embolic signals. Our findings suggest that adoption of topical applications of papaverine hydrochloride may offer opportunities to reduce a portion of cerebral embolic signals in the setting of coronary artery bypass grafting.

Cerebrovascular Circulation↗
PubMed2002

Correlation of thrombophilia and hypofibrinolysis with pulmonary embolism following total hip arthroplasty: an analysis of genetic factors.

BACKGROUND: The increased thromboembolic risk associated with total hip arthroplasty is multifactorial. We assessed whether the prevalence of abnormalities shown by newer genetic screening tests for thrombophilia and hypofibrinolysis was higher in patients in whom pulmonary embolism had developed after total hip arthroplasty than it was in matched control patients. METHODS: Fourteen patients with documented pulmonary embolism after total hip arthroplasty and fourteen matched control patients who had undergone total hip arthroplasty without any clinical indication of thromboembolism were evaluated for risks of thrombophilia and hypofibrinolysis. Functional tests of hemostasis included evaluations of prothrombin time; activated partial thromboplastin time; levels of fibrinogen, serum homocysteine, protein C and S, and antithrombin III; activated protein-C resistance; and dilute Russell viper venom time. Molecular genetic testing was performed for factor-V Leiden, prothrombin promoter G20210A, methylenetetrahydrofolate reductase C677T, plasminogen activator inhibitor-1 4G/4G, and platelet glycoprotein IIb/IIIa A1/A2 or A2/A2 mutations. RESULTS: The total number of genetic thrombophilic abnormalities identified was higher in the pulmonary embolism group (twenty-four abnormalities) than in the control group (fifteen abnormalities). Only patients with pulmonary embolism were found to have heterozygosity or homozygosity for the prothrombin G20210A mutation (four of fourteen patients; p = 0.05 compared with the control group) and a decreased antithrombin-III level (three of thirteen patients; p = 0.10 compared with the control group). Patients with pulmonary embolism were much more likely than control patients to have at least one thrombophilic abnormality: seven of fourteen patients with pulmonary embolism had a low antithrombin-III level or the prothrombin G20210A gene mutation compared with none of the fourteen in the control group (Fisher exact test, p < 0.01). The presence of the prothrombin G20210A gene mutation was significantly correlated with pulmonary embolism (r = 0.41, p = 0.03), as was the presence of least one abnormality (a low antithrombin-III level or the presence of the prothrombin G20210A gene mutation) (r = 0.58, p = 0.001). CONCLUSIONS: Genetic thrombophilia and hypofibrinolysis were more frequent in patients who had had pulmonary embolism after total hip arthroplasty than in those who had not. The presence of multiple genetic thrombophilic polymorphisms, particularly prothrombin G20210A and antithrombin III, rather than any single genetic prothrombotic abnormality, appears to signal an increased thromboembolic risk in patients undergoing total hip arthroplasty. Future refinements and availability of these tests will likely allow preoperative identification of patients with an increased genetic predisposition for thromboembolism.

Arthroplasty, Replacement, Hip↗
PubMed2002

Combined embolization and microsurgery for cerebral arteriovenous malformation.

Thirty-seven of 396 patients with arteriovenous malformations (AVMs) were treated by preoperative embolization and surgical excision in our medical center between 1991 and 1997. The AVMs were Spetzler-Martin grade I in six, grade II in 11, grade III in 12, grade IV in four, and Grade V in four. A total of 69 embolization procedures were performed using estrogen alcohol and polyvinyl acetate as liquid embolization materials. AVM grades improved following embolization in 10 patients. Three hemorrhages occurred several days after the final embolization, probably due to hemodynamic stress on the unoccluded perforating feeders or drainer occlusion. Surgical resection was performed under guidance of intraoperative digital subtraction angiography. Although the AVMs were excised totally in one stage with no major neurological deficits, normal perfusion pressure breakthrough occurred in a patient with prominent collateral circulation of the AVM which developed after the main feeder embolization. Preoperative staged embolization with estrogen alcohol and polyvinyl acetate is effective to expand the surgical indication and to achieve complete resection of difficult AVMs. Direct surgery should be performed as soon as possible if hemodynamic changes are observed following embolization.

Adolescent↗
PubMed2006

Acute pulmonary embolism: correlation of CT pulmonary artery obstruction index with blood gas values.

OBJECTIVE: The purpose of our study was to investigate the relation between the pulmonary artery obstruction index assessed with helical CT and impairment in blood gases in patients with acute pulmonary embolism. SUBJECTS AND METHODS: Helical CT pulmonary angiography was performed in 78 patients who were suspected of having acute pulmonary embolism and selected as being free of underlying cardiopulmonary disease. Findings consistent with acute pulmonary embolism were observed in 34 patients. The severity was assessed by the pulmonary artery obstruction index, defined as Sigma (n x d), where n is the number of segmental arteries occluded and d is the degree of obstruction. Spearman's rank correlation coefficients were used to assess the correlation between the index of arterial obstruction and arterial partial pressure of oxygen (Pao(2)); alveolar-arterial difference in partial pressure of oxygen (Pao(2)-Pao(2)); arterial partial pressure of carbon dioxide (Paco(2)); and arterial oxygen saturation (Sao(2)). The statistical difference of the arterial blood gas values between the two groups of patients (those with and those without pulmonary embolism) was evaluated using the Mann-Whitney U test. Blood gases were comparatively evaluated below and above different index values (from 40% to 70%) and different Paco(2) values (25, 30, and 35 mm Hg) as possible indexes of embolism severity using the same test. The level of significance was set at 95% (p = 0.05). RESULTS: The values of Pao(2), Sao(2), and Paco(2) were significantly lower (p = 0.024, p = 0.0062, and p = 0.000075, respectively) and the values of Pao(2)-Pao(2) were significantly higher (p = 0.0169) in the pulmonary embolism group than in the no-pulmonary-embolism group. A significant correlation was observed between the obstruction index and Pao(2) (r = -0.33, p = 0.05), Paco(2) (r = -0.34, p = 0.05), Pao(2)-Pao(2) (r = 0.39, p = 0.02), and Sao(2) (r = -0.35, p = 0.04). Using cutoff values for the pulmonary artery obstruction index of 40%, 50%, 60%, and 70%, we observed that Paco(2) and Pao(2)-Pao(2) differed significantly between above and below the 40% (p = 0.018 and p = 0.03), 50% (p = 0.0087 and p = 0.029), and 60% (p = 0.005 and p = 0.003) cutoffs. Pao(2) differed significantly for the cutoff values of 60% (p = 0.03) and 70% (p = 0.004). The same was observed for Sao(2) at 60% (p = 0.05) and 70% (p = 0.03). Comparisons for Paco(2) showed that a value of 30 mm Hg significantly separates levels of the pulmonary artery obstruction index (p = 0.002), with 78% sensitivity and 82% specificity indicating a pulmonary artery obstruction index greater than 50%. CONCLUSION: In patients with acute pulmonary embolism but no other underlying cardiopulmonary disease, the severity of the pulmonary arterial tree obstruction assessed using the CT obstruction index is significantly correlated to the blood gas values. The strongest correlation was observed between the index and the Pao(2)-Pao(2). Furthermore, a Paco(2) value of 30 mm Hg or less is highly suggestive of an obstruction index of more than 50% of the arterial bed.

Adult↗
PubMed1988

Arterial embolization of adrenal tumors: results in nine cases.

Adrenal arterial embolization was performed in nine patients, four with inoperable adrenal cortical carcinoma and five with metastatic adrenal tumors. Embolic agents used were polyvinyl alcohol foam (Ivalon) in seven patients, stainless steel coils in four, ethanol in three, and surgical gelatin (Gelfoam) in two. In eight patients, embolization was performed for palliation, either to decrease tumor bulk (all patients), suppress tumor hormonal function (three patients), or relieve pain (four patients). One patient had an embolization to facilitate subsequent adrenalectomy. In four patients in whom it was possible to assess the effect of embolization on tumor bulk by follow-up CT, a striking reduction in size has occurred in one, the lesions remained stable in size for 12 months in two, and the tumor continued to increase in size in the fourth. A striking reduction in the production of the cortisol for 12 months was seen in two of three patients with Cushing syndrome. This reduction was considered due at least in part to embolization. Adrenal embolization resulted in effective palliation of pain in three of four patients and may have contributed to palliation in the fourth. Apart from a hypertensive episode in one patient, the cause of which was unclear, no serious side effects occurred. Adrenal arterial embolization may play an effective role without serious side effects in palliation of pain and reduction of hormone production in inoperable adrenal lesions.

Adrenal Gland Neoplasms↗
PubMed1994

Partial splenic embolization for the treatment of chronic idiopathic thrombocytopenic purpura.

OBJECTIVE: The purpose of this study was to assess the effectiveness of partial splenic embolization in the treatment of chronic idiopathic thrombocytopenic purpura. SUBJECTS AND METHODS: Twenty-six patients with chronic idiopathic thrombocytopenic purpura underwent partial splenic embolization and were followed up for 6-61 months. The condition was refractory to steroids in 20 of 26 patients. The other six patients, in whom a response to steroids was shown, could not be withdrawn from steroid therapy because their platelet counts decreased with any decrease in steroid dose. Five of 26 patients underwent splenectomy after partial splenic embolization, and the other patients were followed up without medical treatment until platelet counts decreased below 3 x 10(10)/l. The therapeutic effect of partial splenic embolization was defined on the basis of the platelet count at the last follow-up after partial splenic embolization: complete response, greater than 10 x 10(10)/l; partial response, 5 x 10(10)/l to 10 x 10(10)/l; and no response, less than 5 x 10(10)/l without medication. RESULTS: Partial splenic embolization brought a complete response in seven (33%) of 21 patients, a partial response in eight (38%), and no response in six (29%). In four of five patients, who later underwent splenectomy, response to partial splenic embolization was coincident with the response to splenectomy. No serious complications occurred, but minor complications such as abdominal pain, fever, and nausea were observed in most patients. CONCLUSION: This study suggests that partial splenic embolization might be useful as an alternative to splenectomy in the treatment of chronic idiopathic thrombocytopenic purpura.

Adult↗
PubMed1995

Pulmonary arteriovenous malformations: results of treatment with coil embolization in 53 patients.

OBJECTIVE: The purpose of this study was to determine the effects of percutaneous transcatheter coil embolization of pulmonary arteriovenous malformations on arterial oxygen saturation, pulmonary gas exchange, anatomic right-to-left shunt, and lung function and to assess the complications of the procedure. SUBJECTS AND METHODS: Fifty-three patients were included in the study: 42 (79%) had associated hereditary hemorrhagic telangiectasia. Nineteen (36%) had neurologic problems compatible with paradoxical embolization. During 102 separate embolization procedures, all malformations with feeding vessels > or = 3 mm in diameter were embolized with steel coils. Arterial oxygen saturation at rest and on exercise and the intrapulmonary right-to-left shunt fraction (99mTc-macroaggregate injection), forced expiratory volume in 1 sec, vital capacity, diffusing capacity for carbon monoxide, and transfer coefficient were measured before and after embolization. Complications of the procedure were recorded and investigated. RESULTS: Before treatment, all patients had hypoxemia in the supine posture (SaO2, 89 +/- 1% [standard error of the mean]), which fell a further 6% (absolute) on standing. Mean values for transfer coefficient and diffusing capacity for carbon monoxide were reduced, at 85 +/- 3% and 78 +/- 3% (predicted value), respectively. After embolization, the mean values for supine and erect SaO2 rose to 94 +/- 1% and 93 +/- 1%. Transfer coefficient increased by a mean of 5.4% of predicted value. The mean shunt fraction fell from 23 +/- 2% preembolization to 9 +/- 1% postembolization. In 102 procedures, there were 18 complications, 12 mild, two moderate, and four potentially serious (systemic coil embolization in two patients, cerebrovascular accident [transient], and myocardial puncture), but there were no lasting sequelae. CONCLUSION: Our results show that coil embolization is an effective and well-tolerated method for treatment of pulmonary arteriovenous malformations. Improvements in pulmonary gas exchange and lung function and a decrease in right-to-left shunting occurred after treatment. The procedure was well tolerated and had a low complication rate.

Adolescent↗
PubMed1999

Clinical validity of helical CT being interpreted as negative for pulmonary embolism: implications for patient treatment.

OBJECTIVE: The purpose of our study was to assess the clinical usefulness of helical CT findings that are interpreted as negative for pulmonary embolism. MATERIALS AND METHODS: One hundred twenty-six patients underwent 132 helical CT examinations and 352 patients underwent ventilation-perfusion scanning for suspected acute pulmonary embolism over a 17-month period at a single institution. Findings from clinical follow-up at a minimum of 6 months were assessed, with a special focus on the presence of recurrent thromboembolism and mortality in 78 consecutive patients in whom helical CT findings were interpreted as negative for pulmonary embolism and anticoagulant therapy was not administered (group I). During the same 17-month period, 46 patients underwent ventilation-perfusion scanning that was interpreted as normal (group II), and 132 patients underwent ventilation-perfusion scanning that was interpreted as showing a very low to low probability for pulmonary embolism (group III). Patients in groups II and III did not undergo helical CT or pulmonary angiography and did not receive anticoagulant therapy. However, clinical follow-up was solicited. Patients from groups II and III were used as control subjects. RESULTS: Nine patients in group I died, one of whom was found to have a microscopic pulmonary embolism at autopsy. In group II, four patients died, none of whom were shown to have a missed or recurrent pulmonary embolism. Of the 18 patients in group III who died, three had a recurrent or missed pulmonary embolism (mean interval, 9 days), and two were found to have deep vein thrombosis on sonography of the leg (mean interval, 12 weeks). Negative predictive values for helical CT, normal lung scanning, and low-probability ventilation-perfusion scanning were 99%, 100%, and 96%, respectively (p = .299). CT provided either additional findings or an alternate diagnosis in 42 (53.8%) of the 78 patients in whom helical CT findings had been interpreted as negative for pulmonary embolism. CONCLUSION: A helical CT scan can be effectively used to rule out clinically significant pulmonary emboli and may prevent further investigation or unnecessary treatment of most patients.

Adult↗
PubMed2001

Uterine artery embolization for the treatment of adenomyosis: clinical response and evaluation with MR imaging.

OBJECTIVE: This study was performed to evaluate the MR imaging appearance and clinical response of patients undergoing uterine artery embolization for the treatment of menorrhagia due to adenomyosis. MATERIALS AND METHODS: A retrospective review of 15 patients with adenomyosis and menorrhagia who underwent uterine artery embolization was performed. The diagnosis of adenomyosis was based on established MR imaging criteria. Clinical response was assessed at a minimum of 3 months after embolization. Follow-up MR imaging was performed 6 months after embolization. RESULTS: Of the 15 patients in this study, five had diffuse adenomyosis without evidence of uterine fibroids, one had focal adenomyosis without evidence of uterine fibroids, and the remaining nine had adenomyosis with one or more fibroids. At follow-up, 12 (92.3%) of the 13 patients reported significant improvement in presenting symptoms and quality of life. One patient continued experiencing menorrhagia, and one patient experienced amenorrhea during the 5 months of follow-up after embolization. MR imaging in nine patients, performed at a mean of 5.9 months after embolization, revealed significant reductions in median uterine volume (42%), median fibroid volume (71%), and mean-junctional-zone thickness (11 mm; 33%; p < 0.5). Six of the nine patients had subendometrial regions of decreased T2 signal intensity after embolization. CONCLUSION: Uterine artery embolization is a promising nonsurgical alternative for patients with menorrhagia and adenomyosis. Significant improvement in presenting symptoms and in quality of life is associated with decreases in uterine size and junctional zone thickness. Larger prospective studies are needed to establish the safety and efficacy of this procedure for patients with adenomyosis.

Arteries↗
PubMed2001

Gadolinium-enhanced MR imaging in the evaluation of uterine fibroids treated with uterine artery embolization.

OBJECTIVE: The purpose of this study was to determine whether tumor volume reduction can be predicted by the infarction rate of uterine fibroids as seen on gadolinium-enhanced MR images obtained immediately after uterine artery embolization. MATERIALS AND METHODS: In our study, 36 women with symptomatic uterine fibroids successfully underwent uterine artery embolization. Unenhanced and enhanced MR imaging was performed before the procedure and repeated at 1 week, 4 months, and 1 year after the procedure. We retrospectively reviewed enhanced MR images of uterine fibroids after uterine artery embolization. At 4 months after uterine artery embolization, we compared the rate of tumor volume reduction in patients with completely infarcted dominant fibroids with the rate of tumor volume reduction in patients with partially infarcted fibroids. RESULTS: Enhanced MR images obtained 1 week after uterine artery embolization revealed that 100% infarction rates of the dominant uterine fibroids were achieved in 33 women (92%), and 70--90% infarction rates were seen in the remaining three (8%). They also revealed that of a total of 204 fibroids in these patients, 100% infarction was achieved in 199 fibroids (98%). Enhanced MR images obtained 4 months after uterine artery embolization showed that tumor volume reduction of the completely infarcted dominant fibroids (n = 23) was 60% +/- 18%, whereas that of the partially infarcted fibroids (n = 5) was 35% +/- 27% (p = 0.0367). CONCLUSION: Gadolinium-enhanced MR imaging is a useful diagnostic technique for uterine fibroids after uterine artery embolization because it assesses the degree of infarction in the embolized fibroids, which corresponds to the subsequent tumor volume reduction.

Adult↗