The case of Abbokinase and the FDA: the events leading to the suspension of Abbokinase supplies in the United States

Review: High temperature short time treatment of cell culture media and feed solutions to mitigate adventitious viral contamination in the biopharmaceutical industry

Events of viral contaminations occurring during the production of biopharmaceuticals have been publicly reported by the biopharmaceutical industry. Upstream raw materials were often identified as the potential source of contamination. Viral contamination risk can be mitigated by inactivating or eliminating potential viruses of cell culture media and feed solutions. Different methods can be used alone or in combination on raw materials, cell culture media, or feed solutions such as viral inactivation technologies consisting mainly of high temperature short time, ultraviolet irradiation, and gamma radiation technologies or such as viral removal technology for instance nanofiltration. The aim of this review is to present the principle, the advantages, and the challenges of high temperature short time (HTST) technology. Here, we reviewed effectiveness of HTST treatment and its impact on media (filterability of media, degradation of components), on process performance (cell growth, cell metabolism, productivity), and product quality based on knowledge shared in the literature.

Intrapleural Tissue Plasminogen Activator for Traumatic Retained Hemothorax

Objective: To describe the efficacy, safety, dosing regimen, and administration technique of intrapleural alteplase for the treatment of retained hemothorax. Data Sources: A PubMed, EMBASE, and Google Scholar search (January 2000 to February 2019) was conducted with the search terms intrapleural, fibrinolytic, fibrinolysis, alteplase, tissue plasminogen activator, and hemothorax. Study Selection and Data Extraction: Articles were included if they described the use of intrapleural alteplase in adult patients with a retained hemothorax; single patient case reports and abstracts were excluded. Data Synthesis: A total of 6 retrospective reviews and 1 meta-analysis were identified for inclusion. A variety of dosing strategies have been defined for the administration of intrapleural alteplase ranging from 6 to 100 mg, volume of fluid from 50 to 120 mL of normal saline, and the number of total doses has ranged from 1 to 8 over the treatment course. A majority of studies showed a greater than 80% success rate and less than 7% bleeding rate. Relevance to Patient Care and Clinical Practice: Because of the paucity of data for use of alteplase in retained hemothorax and administration of a high-risk medication, this review provides dosing and administration recommendations based on reported safety and efficacy. Conclusion: Administration of intrapleural alteplase should be considered in patients with retained hemothorax as an alternative to surgical intervention. In contrast to intrapleural alteplase administration for other indications such as empyema, higher doses and volumes of alteplase are recommended for retained hemothorax.

Efficacy, safety, and cost of thrombolytic agents for the management of dysfunctional hemodialysis catheters: a systematic review

Approximately 100,000 patients begin hemodialysis each year in the United States. Although an arteriovenous fistula or graft is the preferred method for long-term vascular access during hemodialysis, as these types of vascular access are the most reliable, approximately 30% of patients require the use of catheters to continue hemodialysis. Tunneled, cuffed hemodialysis catheters are discouraged for permanent vascular access because of their high rates of infection, morbidity and mortality, and thrombotic and technical complications. These catheters have a short functional life span and require medical intervention, often thrombolytic therapy, to treat the catheter malfunction. No thrombolytic agent is specifically indicated for the management of occluded hemodialysis catheters. Thus, we performed a systematic review to critically evaluate all available studies that examined the efficacy, safety, and cost of thrombolytic therapy for the management of dysfunctional hemodialysis catheters. Studies were included if they reported efficacy in a specific proportion of affected dysfunctional hemodialysis catheters; reported the proportion of patients experiencing an adverse outcome (especially bleeding); and described the type of catheter used, dose of thrombolytic agent, administration protocol, dwell time, definition of treatment success, time to follow-up for study end points, and sample size. Eighteen studies met the inclusion criteria. The mean ± SD success rate in clearing dysfunctional hemodialysis catheters was greatest with reteplase at 88 ± 4%, followed by alteplase at 81 ± 37% and tenecteplase at 41 ± 5%. Adverse effects associated with the use of these thrombolytic agents administered at low doses were extremely rare. No serious adverse bleeding events attributed to thrombolytic therapy were reported in any of the trials. Aliquotted reteplase from vials for intravenous use was the least costly thrombolytic agent. Thus, at centers that use high volumes of thrombolytics for dysfunctional hemodialysis catheters, reteplase is the thrombolytic agent of choice.

Clinical utility of novel agents in the treatment of central venous catheter occlusion

Central venous catheter (CVC) occlusion occurs frequently and remains a significant clinical problem in patients with cancer receiving infusional or intravenous chemotherapy. Thrombotic occlusions frequently limit the benefits of potentially curable cytotoxic agents by interrupting the delivery of infusion of chemotherapy, intravenous medication, nutritional support, and blood products, as well as the frequent acquisition of venous blood samples for laboratory testing. Urokinase has been used as a thrombolytic agent for dysfunctional occluded CVCs, but the alterations in manufacturing practice prompted the Food and Drug Administration to suspend further production of urokinase in 1999. Although streptokinase had a potential as a thrombolytic agent in place of urokinase, the risk of life-threatening anaphylaxis associated with this agent prompted researchers to look for newer agents to dissolve CVC occlusions. Several novel thrombolytic agents are currently being evaluated as a potential treatment for patients with CVC occlusions and acute or chronic peripheral arterial occlusions. Alfimeprase, a recombinant fibrinolytic zinc metalloprotease, has shown promising clinical utility in blood clot lysis in patients with CVC occlusions and peripheral arterial occlusions. Based on the encouraging data, alfimeprase has received orphan drug designation from the Food and Drug Administration and the Committee for Orphan Medicinal Products of the European Medicines Agency for the evaluation of acute peripheral arterial occlusions as a potential indication. Other novel thrombolytic agents such as alteplase and reteplase are undergoing clinical evaluation for their utility in restoring the function of occluded CVCs. The clinical potency of these novel agents and their ongoing clinical trials are discussed briefly herein.

Intrapleural r-tPA in association with low-molecular heparin may cause massive hemothorax resulting in hypovolemia

The use of intrapleural instillation of recombinant tissue plasminogen activator (r-tPA) in the treatment of pleural infection may increase pleural fluid drainage associated with a clinical and imaging improvement, leading to a faster resolution. The use of r-tPA is generally well tolerated. Here we report 2 cases of massive pleural hemorrhage resulting in life-threatening hypovolemia, in 2 patients treated with intrapleural r-tPA for a pleural infection, who were simultaneously receiving systemic anticoagulation (1 therapeutic, the second prophylactic) with low-molecular weight heparin. It appears that the decision of treating pleural infection with r-tPA in patients receiving therapeutic or prophylactic systemic anticoagulation must be well balanced and in case of association of these compounds, close monitoring is necessary.

Transient intradural catheter lysis in a patient with a diffuse and elongated subdural hematoma of the spine due to trauma. Case report

The often extended and elongated configuration of a diffuse subdural hematoma of the spine makes it impossible to completely evacuate with common neurosurgical approaches. The authors describe the complete evacuation of a diffuse subdural hematoma of the entire spine due to trauma in a patient who suffered myelopathy and paraplegia in succession, by using transient subdural catheter lysis. After the patient underwent a partial hemilaminectomy at T7-8 and L2-3 using a lateral transmuscular approach, a 15 cm-long intraventricular catheter was inserted at each hemilaminectomy site and connected to an external ventricular drainage system in a procedure lasting 1 hour. Subsequently, 5000 IU of urokinase was applied four times daily for 30 minutes each time over the next 5 days. Two months later, the patient presented with spastic paraparesis Manual Muscle Test Grade 4/5. Magnetic resonance (MR) imaging revealed no catheter-related complications. The authors conclude from this case that transient catheter lysis may be an effective and gentle method to treat diffuse and elongated subdural hematomas of the spine due to trauma. A larger series needs to be analyzed, however, to address the indications and limitations of the technique compared with conventional open surgery. Such evaluation should include serial MR imaging and electrophysiological examination.

Synthesis, regulation and production of urokinase using mammalian cell culture: a comprehensive review

Urokinase, a serine protease, catalyzes the conversion of plasminogen to plasmin, which is responsible for dissolution of clots in blood vessels. It is an important drug for treatment of thromboembolic disease. Production of urokinase by mammalian cell culture has the following important steps: synthesis, regulation and secretion. Production and accumulation of this product in a bioreactor is a real challenge for biochemical engineers. Considerable information at molecular level needs to be understood for production of urokinase in order to correlate different parameters, which in turn can maximize the productivity. This information will be highlighted in this review. Moreover, urokinase production is a product-inhibited process. Therefore, in situ urokinase separation strategy is required to operate a bioreactor at its maximum urokinase formation rate. Integrated urokinase production and isolation processes developed recently will also be discussed briefly in this review.

Intrapleural Tissue Plasminogen Activator for Complicated Pleural Effusions

BACKGROUND

This study is aimed at evaluating the safety and efficacy of intrapleural tissue plasminogen activator (TPA) for complicated pleural effusions, including posttraumatic hemothorax.

METHODS

Data were retrospectively collected from hospitalized patients over a 4-year period (1999-2003) who were treated with intrapleural TPA after failing drainage by tube thoracostomy. Pre- and post-TPA imaging studies were reviewed and scored by a blinded radiologist.

RESULTS

Forty-one consecutive patients with 42 effusions were identified with the following indications: 6 traumatic hemothoraces (14%), 22 loculated pleural effusions (52%), 2 line-associated hemothoraces (5%), and 12 empyemas (29%). Nine patients (22%) required operative drainage including two with posttraumatic hemothoraces. All patients managed nonoperatively demonstrated radiographic improvement after TPA administration. One patient (2.4%) developed hematuria, requiring transfusion. No trauma patient required TPA-related blood transfusion and no deaths were attributable to TPA therapy.

CONCLUSION

Intrapleural TPA administration appears safe for use in complicated pleural effusions and may decrease the need for operative intervention.

Reteplase with or without Abciximab for Peripheral Arterial Occlusions: Efficacy and Adverse Events

PURPOSE

To retrospectively evaluate reteplase in thrombolysis of peripheral arterial occlusion (PAO).

MATERIALS AND METHODS

Forty limbs in 36 patients were treated with reteplase (0.5 U/h) with or without abciximab (bolus and 12-hour infusion). Twenty-four occlusions were in bypass grafts and 16 were in native arteries. Nineteen patients were treated with reteplase alone and 21 patients were treated with reteplase and abciximab. Chart review provided data from procedures and follow-up at 30 days and 6 months. Multivariable, analysis of variance, and Student t test comparisons of results and complications were performed.

RESULTS

Reteplase infusions averaged 31 hours in duration (range, 12-72 hours). The technical success rate was 80%. The clinical success rates were: immediate, 80%; 30-day, 65%; and 6-month, 45%. Major bleeding complications occurred in 20% of cases and intracranial hemorrhage occurred in 2.5%. The 6-month amputation-free survival rate was 78%. Major, minor, and lack of complications were statistically associated with mean decreases in fibrinogen levels from baseline of 72%, 46%, and 15%, respectively (P =.000013). Complications were not associated with length of infusion or use of abciximab (P =.77). Patients with grafts accounted for 89% of the major complications (eight of nine; P =.009) and had worse clinical success immediately (71%), at 30 days (50%), and at 6 months (21%; P =.002, P =.003, P =.00001).

CONCLUSIONS

There was significant fibrinogen depletion with use of reteplase for PAO. The percent decrease in fibrinogen level correlates with lack of complications and incidence of minor and major complications. Abciximab use did not increase the complication rate. Thrombolysis of grafts is associated with increased incidence of complications and worse outcomes compared with thrombolysis of native arteries.

Controlled gamma-irradiation mediated pathogen inactivation of human urokinase preparations with significant recovery of enzymatic activity

Human sources of urokinase have led to the contamination of in-process lots of commercially available material with human pathogens. Effective pathogen inactivation of urokinase preparations can be achieved through the use of gamma-irradiation. Additionally, the presence of a free radical scavenger (ascorbate) and the control of temperature have resulted in maintenance of the enzymatic activity of urokinase without a significant effect on the pathogen inactivation properties of gamma-irradiation. In this study we have optimized the conditions during gamma-irradiation to achieve inactivation of porcine parvovirus by 5 logs and vaccinia virus to levels below the limits of detection, while maintaining 92% of urokinase activity. Product specific optimization of gamma-irradiation has the potential to provide effective pathogen inactivation while maintaining substantial functional activity for many therapeutic proteins.

Central venous catheter occlusion and thrombosis

Central venous catheters are widely used in children with critical illness and chronic disease. These devices are often essential in the delivery of medications and intravenous fluids and in hemodynamic monitoring. Central venous catheter occlusion and thrombosis are common problems in patients using these devices. This article reviews the background, pathophysiology, and incidence of catheter occlusion and catheter-related thrombosis. Diagnostic, preventive, and treatment strategies, along with future research directions, are addressed.

Catheter-directed thrombolytic therapy in peripheral artery occlusions: combining reteplase and abciximab

OBJECTIVE

The goal of this study was to assess the safety and efficacy of combination therapy consisting of the third-generation plasminogen activator reteplase and the glycoproteins IIb and IIIa platelet receptor antagonist abciximab for thrombolysis in peripheral artery occlusive disease. This two-center experience focused on immediate thrombolytic success, thrombolysis time, complication rate, and 30-day patency rate.

SUBJECTS AND METHODS

Fifty patients with arterial occlusive disease (age range, 40-96 years; mean age, 69 years) were prospectively enrolled at two centers. Eighteen patients (36%) had native artery thromboses, and 32 patients (64%) had graft thromboses. Catheter-directed intraarterial thrombolytic infusion of reteplase (average dose, 0.51 U/hr; range, 0.25-1 U/hr) was combined with IV infusion of abciximab (bolus, 0.25 mg/kg of body weight; 12-hr infusion, 0.125 microg/kg of body weight per minute). Nontherapeutic heparin (100-400 U/hr) was given intraarterially during the thrombolytic infusion.

RESULTS

Complete thrombolysis was achieved in 89% of the patients with native artery occlusions and 94% of the patients with graft occlusions for an overall rate of 92%. The average thrombolysis time was 20.7 hr (range, 4-41 hr) with a mean reteplase dose of 12.1 U (range, 2-23 U). Major hematoma occurred in 12% of the patients, with an average blood transfusion of 3.1 U of packed RBC (range, 1-11 U), and correlated to increased thrombolysis time and dose. No intracranial hemorrhage occurred. The 30-day primary patency rate was 92%. Two patients (4%) underwent amputation, including one major amputation (2%), within 30 days of thrombolysis.

CONCLUSION

The combination of reteplase and abciximab in catheter-directed arterial thrombolysis is feasible and effective. Results of this combination therapy suggest acceptable thrombolysis times and doses with tolerable complication rates. Which patient group might benefit the most from combination therapy and the long-term results of combination therapy still need to be determined.

The safety, efficacy, and pharmacoeconomics of low-dose alteplase compared with urokinase for catheter-directed thrombolysis of arterial and venous occlusions

PURPOSE

The purpose of this study was to compare the efficacy, complications, and costs associated with low-dose (<2 mg/h) alteplase (tissue plasminogen activator [t-PA]) versus urokinase for the catheter-directed treatment of acute peripheral arterial occlusive disease (PAO) and deep vein thrombosis (DVT).

MATERIALS AND METHODS

A retrospective review was performed during sequential time periods on two groups with involved extremities treated with either t-PA with subtherapeutic heparin (TPA group) or urokinase with full heparin (UK group) at a single center. Treatment group characteristics, success rates, complications, dosages, infusion time, and costs were compared.

RESULTS

Eighty-nine patients with 93 involved limbs underwent treatment (54 with DVT, 39 with PAO). The treatment groups were statistically identical (TPA: 45 limbs; 24 with DVT, 53.3%; 21 with PAO, 46.7%; UK: 48 limbs; 30 with DVT, 62.5%; 18 with PAO, 37.5%). The overall average hourly infused dose, total dose, infusion time, success rates, and cost of thrombolytic agent were as follows (+/- standard deviation): TPA, 0.86 +/- 0.50 mg/h, 21.2 +/- 15.1 mg, 24.6 +/- 11.2 hours, 89.4%, $466 +/- $331; and UK, 13.5 +/- 5.6 (10(4)) U/h, 4.485 +/- 2.394 million U, 33.3 +/- 13.3 hours, 85.7%, $6871 +/- $3667, respectively. Major and minor complication rates were: TPA, 2.2% and 8.9%; and UK, 2.1% and 10.4%, respectively. No statistical differences in success rates or complications were observed; however, t-PA was significantly (P <.05) less expensive and faster than urokinase.

CONCLUSION

Low-dose t-PA combined with subtherapeutic heparin is equally efficacious and safe compared with urokinase. Infusions with t-PA were significantly shorter and less expensive than those with urokinase.

Recombinant tissue plasminogen activator (alteplase) for restoration of function to occluded central venous catheters in pediatric patients

PURPOSE

To evaluate the safety and efficacy of alteplase for restoring function to occluded central venous catheters in a pediatric population.

PATIENTS AND METHODS

A phase III, open-label, single-arm, multicenter trial was performed in 995 adult and pediatric patients with dysfunctional nondialysis catheters and ports. This report is a subset analysis of subjects between 2 and 18 years of age (N = 122) who were enrolled in the study. Alteplase (2 mg/2 mL) was instilled into the dysfunctional catheter lumen and assessed at 30 and 120 minutes. Subjects weighing > or =30 kg received 2 mL of alteplase; subjects <30 kg received 110% of the internal lumen volume (not exceeding 2 mL). Alteplase dosing was repeated once after 120 minutes if the catheter remained dysfunctional. The primary safety endpoint was the rate of intracranial hemorrhage (ICH) within 5 days of treatment.

RESULTS

The overall efficacy following up to two instilled doses of alteplase was 87%. In 70 patients (57%), restoration of catheter flow occurred by 30 minutes following a single dose of alteplase. Restoration of function was related to the duration of occlusion (P = 0.04). For catheters with occlusions of 0, 1 to 14, and >14 days duration, the efficacy was 91%, 78%, and 60%, respectively. Success was independent of the patient's age, sex, body weight, CVC type, or catheter age. There were no cases of death, ICH, major bleeding episodes, or embolic events attributable to treatment.

CONCLUSIONS

An alteplase regimen of up to two 2-mg doses is safe and effective for restoration of function to occluded central venous catheters in a pediatric population.

Initial experience with the combination of reteplase and abciximab for thrombolytic therapy in peripheral arterial occlusive disease: a pilot study

PURPOSE

To report the efficacy of catheter-directed thrombolysis with a combination of a thrombolytic agent (reteplase) and a glycoprotein (GP) IIb/IIIa platelet receptor antagonist (abciximab) in peripheral arterial occlusive disease.

MATERIALS AND METHODS

Fifteen patients with lower extremity arterial thromboses (age range, 40-96 y; mean, 73 y) were prospectively enrolled in a protocol approved by the Institutional Review Committee. Nine patients had native arterial occlusions, three (33%) of whom had subacute symptoms (>14 d) and one of whom had chronic symptoms (>3 mo). Four patients had acute arterial graft thromboses. Two patients with lower extremity bypass grafts presented with subacute limb ischemia. All patients received catheter-directed infusion of reteplase (0.5 U/h) in combination with intravenous administration of abciximab (0.25-mg/kg bolus followed by 0.125 microg/kg/min infusion) for 12 hours without systemic heparinization. The thrombolytic success was studied by Doppler ultrasonography (US) and angiography.

RESULTS

Complete thrombolysis and clinical success was achieved in 14 of the 15 patients (93%). One patient with unsuccessful thrombolysis underwent major amputation. The mean thrombolysis time per Doppler US procedure was 6.8 hours (range, 2-30 h). Angiographic patency was achieved at a mean of 17.5 hours (range, 4-36 h) corresponding to a mean dose of reteplase of 8.8 U. The mean increase in ankle-brachial index was 0.52 (range, 0-0.9). No major hemorrhagic complications occurred. The 30-day primary patency rate was 93%.

CONCLUSION

The combination of reteplase and abciximab in catheter-directed arterial thrombolysis is feasible and effective. This combination therapy pilot study suggests short thrombolysis times and minimal adverse effects in catheter-directed thrombolytic therapy for peripheral arterial occlusive disease.

Weight-based rt-PA thrombolysis protocol for acute native arterial and bypass graft occlusions

PURPOSE

To determine technical success and complications with weight-adjusted dosing of recombinant tissue plasminogen activator (rt-PA) for arterial and bypass graft occlusions.

MATERIALS AND METHODS

During an 8-month period, prospective data were collected on patients undergoing catheter-directed thrombolysis. Retrospective review of all medical charts and blood bank data were performed for confirmation. All patients underwent a standard weight-adjusted protocol for catheter-directed thrombolysis. Thrombolytic therapy with rt-PA (0.2 mg/mL) was defined as low-dose when 0.02 mg/kg/h rt-PA was used and high-dose when 0.04 mg/kg/h of rt-PA was used. Low-dose heparin therapy was used. Total infusion time, total dose, and hourly rate of dose were calculated. Technical success, defined as complete removal of all clot without surgical intervention, complications, and frequency of transfusions were tabulated.

RESULTS

A total of 35 patients underwent catheter-directed thrombolysis with rt-PA, including a total of 21 bypass grafts (60%) and 14 native arteries (40%). Mean age was 57 years (+/- 22.5; range, 3 mo to 83 y). Average rate of heparin infusion was 472.8 U/h (+/- 227). Success rates for graft thrombolysis were 90% (18 of 21). Success rates for native vessels were 79% (11 of 14). In patients who underwent only a low-dose protocol, the transfusion rate was 15% and major complications were 10%. In patients with a combined low-dose/high-dose administration, the transfusion rate was 46% and major complications were 13%. Overall success rate and major complication rates were 86% (30 of 35) and 11% (four of 35), respectively. Frequency of transfusions was 37% (13 of 35; mean, 2.8 U).

CONCLUSION

Although weight-adjusted dosing for rt-PA provides a high efficacy of relieving ischemia, the rate of complications, especially bleeding, seems excessive in comparison to historical experience with urokinase. Administration of short-term high doses of rt-PA did not appear to have any beneficial effect. Further investigation with lower dosing and concentration should be considered.

Safety and efficacy of alteplase for restoring function in occluded central venous catheters: results of the cardiovascular thrombolytic to open occluded lines trial

PURPOSE

To evaluate the safety and efficacy of alteplase (TPA) for restoring function to occluded central venous catheters (CVCs).

PATIENTS AND METHODS

The study design was a phase III, open-label, single-arm multicenter trial. Subjects with occluded, nondialysis CVCs were enrolled. All subjects received a 2-mg dose of TPA within the dysfunctional catheter lumen that was allowed to dwell for 30 to 120 minutes. Functionality was tested at 30 and 120 minutes. If the CVC remained obstructed at 120 minutes, a second 2-mg TPA dose was allowed to dwell for 30 to 120 minutes. The primary safety end point was the rate of intracranial hemorrhage (ICH) within 5 days of treatment, and serious adverse events were recorded up to 30 days.

RESULTS

Nine hundred ninety-five patients received treatment (female, 562; male, 433; mean age, 50.7 years; range, 2 to 91 years). CVCs treated were as follows: single (26%), double (39%), or triple (6%) lumen catheters or ports (29%). The primary end point was 0% ICH within 5 days. There were no cases of death, major bleeding episodes, or embolic events attributable to treatment. Flow was successfully restored in 52% and 78% of CVCs at 30 and 120 minutes after one dose, and 84% and 87% at 30 and 120 minutes after a second dose, respectively. Restoration of flow was 86%, 93%, 90%, and 79%, for single, double, and triple lumen catheters and ports, respectively. Estimated 30-day catheter patency was 74%.

CONCLUSION

A regimen of up to two 2-mg doses of TPA is safe and effective for the restoration of flow to occluded central venous catheters.

Nonlocalized lower gastrointestinal bleeding: provocative bleeding studies with intraarterial tPA, heparin, and tolazoline

PURPOSE

The purpose of this study was to assess the efficacy and safety of provocative mesenteric angiography with tissue plasminogen activator (tPA), heparin, and tolazoline in patients with nonlocalized lower gastrointestinal (LGI) bleeding. Results were examined to assess the clinical impact of the study on patients who had positive or negative results from elective provocative bleeding studies.

MATERIALS AND METHODS

Seventeen provocative bleeding studies for occult LGI bleeding were performed in 16 patients, nine of whom were women, aged 44-79 years. All patients had negative results from previous endoscopic and angiographic studies. Patients' requirements for blood transfusion ranged from 6 to 69 units. Studies were performed electively. Blood group matching and cross-matching were performed for all patients. To provoke bleeding, a combination of intravenous heparin, intraarterial tolazoline, and intraarterial tPA was used. Doses used included 3,000-10,000 U heparin, 25-100 mg intraarterial tolazoline, and 10-50 mg intraarterial tPA (mean, 20.3 mg). Duration of follow-up was 3-34 months.

RESULTS

Seventeen elective provocative studies were performed in 16 patients with occult LGI bleeding, leading to provoked bleeding in six patients (37.5%). In addition, two previously undiagnosed vascular abnormalities were diagnosed, which did not bleed during provocation. Therefore, an abnormality was identified in eight of 16 patients (50%) overall. There were no procedural complications encountered during or after any of the 17 procedures. In six patients in whom bleeding was successfully provoked, four bleeding episodes occurred in the large bowel and two occurred in the small bowel. Five of the positively provoked patients had a previously positive tagged red cell scintigraphic study. Three patients had superselective embolization at the time of provoked bleeding. Two were treated with estrogen therapy, and one patient was treated palliatively. Five of these six patients required no further therapy for LGI bleeding. Ten patients (including two with vascular abnormalities) did not bleed during the provoked study with tPA. Follow-up of the group of eight patients with completely normal study results ranged from 3 to 34 months in duration, and during the follow-up period, five patients experienced repeated bleeding and one had no further bleeding. One patient was diagnosed with an ileal vascular lesion during subsequent intraoperative enteroscopy and underwent surgical resection. One patient was lost to follow-up.

CONCLUSION

Intraarterial provocative mesenteric angiography with heparin, vasodilator, and tPA identified the site of bleeding in 37.5% of patients in our study group and contributed to treatment in 50%. This small study indicates that the procedure appears to be safe, with no complications encountered in this series. Larger prospective studies are needed to fully assess the safety and efficacy of the technique and to optimize the pharmacologic protocol and patient selection.