Interventional Therapies for Acute Pulmonary Embolism: Current Status and Principles for the Development of Novel Evidence: A Scientific Statement From the American Heart Association

Pulmonary embolism (PE) represents the third leading cause of cardiovascular mortality. The technological landscape for management of acute intermediate- and high-risk PE is rapidly evolving. Two interventional devices using pharmacomechanical means to recanalize the pulmonary arteries have recently been cleared by the US Food and Drug Administration for marketing, and several others are in various stages of development. The purpose of this document is to clarify the current state of endovascular interventional therapy for acute PE and to provide considerations for evidence development for new devices that will define which patients with PE would derive the greatest net benefit from their use in various clinical settings. First, definitions and limitations of commonly used risk stratification tools for PE are reviewed. An adjudication of risks and benefits of available interventional therapies for PE follows. Next, considerations for optimal future evidence development in this field are presented in the context of the current US regulatory framework. Finally, the document concludes with a discussion of the pros and cons of the rapidly expanding PE response team model of care delivery.

Use of a Modified Cardiopulmonary Bypass Circuit for Suction Embolectomy with the AngioVac Device

The AngioVac suction cannula and circuit were designed for the percutaneous removal of soft thrombus and emboli in procedures requiring extracorporeal circulatory support. We describe a modification of the AngioVac suction catheter and cardiopulmonary bypass (CPB) circuit to effectively remove thrombus while maintaining the ability to rapidly initiate full CPBs during a medical crisis. This article will discuss the design concepts of the modified circuit as well as procedural protocols and considerations. The design modifications of incorporating an oxygenator, reservoir, and bridge allow for an increased flexibility that allows adaption to veno-venous extracorporeal membrane oxygenation or full CPB support when required for oxygenation or hemodynamic support.

Percutaneous Embolectomy of Serpentine Thrombus from the Right Atrium in a 51-Year-Old Man

Treatment of large, fresh thrombi in the vascular system can be challenging. AngioVac, a cardiopulmonary pump system, has been used to remove large thrombi and even some tumors by a percutaneous route. We report here a case of a 51-year-old man who presented with a large thrombus (7.5 × 1.5 cm) in his inferior vena cava, extending into his right atrium and right ventricle. Because the surgical risk was high, we attempted percutaneous embolectomy via the AngioVac aspiration system. We also review the literature concerning this emerging technique.

Erfolgreiche lokale Katheterfragmentation und Thrombolyse bei akuter Lungenembolie in der frühen postoperativen Phase nach Pankreaskopfresektion

Pulmonary embolism in the early postoperative period is characterized by high morbidity and mortality. Systemic application of thrombolytic agents during this time is contraindicated; operative thrombectomy also has a high mortality rate. We report a case of successful local lysis in combination with catheter fragmentation of a massive two-sided pulmonary embolism diagnosed on the 4th postoperative day after pylorus-preserving duodenopancreatectomy for distal carcinoma of the common bile duct. Thrombolysis was performed in three sessions by a combination of catheter-supported interventional fragmentation of the thrombus with local rt-PA lysis. There were no bleeding complications or disturbances of anastomotic healing. The patient was discharged from the hospital on the 23rd postoperative day after changing anticoagulation to a vitamin K antagonist. The case presented demonstrates the possibility of local lysis in combination with interventional methods as a therapeutic option for pulmonary embolism in the early postoperative period as an alternative to surgical strategies.

Design and development of mechanical embolic protection devices

Carotid angioplasty and stenting (CAS) is rapidly becoming an acceptable alternative to carotid endarterectomy in many patients. Much of the success of CAS is credited to advances in equipment dedicated to this minimally invasive approach. Lower profile delivery systems, tapered stent designs and most importantly, development of mechanical cerebral embolic protection devices (EPDs) have contributed to a reduction in periprocedural neurological complications that now rival results of carotid endarterectomy. Despite a lack of level one evidence in support of EPDs, a meta-analysis as well as two recent institutional reports of CAS with and without EPDs suggest a reduced stroke risk when a mechanical protection device is incorporated as part of the procedure. Since the original description by Theron and colleagues, embolic protection systems are markedly improved in ease of use and effectiveness. The three primary groups of EPDs are distal balloon occlusion, distal filtration and proximal occlusion. Although the ideal EPD has yet to materialize, this review provides insight into current design systems and the accompanying strengths and weaknesses of each.

Hybrid procedures for acute limb ischemia

The most efficient treatment for acute arterial embolism is operative embolectomy using Fogarty's balloon catheter, especially if a single large artery is involved. Unfortunately, although the early surgical success of arterial thromboembolectomy often seems acceptable, the early clinical outcome still remains unsatisfactory. This may be related to the incomplete restoration of perfusion (i.e., residual thrombus in distal vessels not reached by the balloon catheter thromboembolectomy), propagation of residual thrombi or presence of underlying steno-occlusive lesions. In such a situation a meticulous intraoperative assessment of the adequacy of clot removal is decisive. Residual thrombus, chronic atherosclerotic disease and even vessel injuries secondary to balloon catheter passage can be corrected by endovascular techniques (hybrid procedures). The combination of surgical and endovascular options may overcome the limitations that characterize the traditional approach, and it is likely that in the future many treatments will be a mix of techniques that can be performed by vascular surgeons in the operating room or in a dedicated endovascular suite. This review article summarizes the hybrid treatment options for acute arterial occlusion caused by either embolism or local thrombosis.

Mechanical thrombectomy with the Solitaire AB device in large artery occlusions of the anterior circulation: a pilot study

BACKGROUND AND PURPOSE

To describe the safety and effectiveness of a self-expanding and fully retrievable stent (Solitaire AB; ev3 Inc, Plymouth, MN) in revascularization of patients with acute ischemic stroke.

METHODS

Prospective, single-center study of 20 patients with an acute ischemic stroke attributable to a large artery occlusion of the anterior circulation within the first 8 hours from symptoms onset (median National Institutes of Health Stroke Scale, 19 [interquartile range, 15-23]). The occlusion site was middle cerebral artery in 12 patients, proximal internal carotid artery/middle cerebral artery tandem occlusion in 3 patients, and terminus internal carotid artery in 5 patients. Thrombectomy was used as rescue therapy in 2 patients who were refractory to intra-arterial plasminogen activator, and in 3 patients in whom successful recanalization with the MERCI retriever was not achieved.

RESULTS

Successful revascularization defined as thrombosis in cerebral ischemia grade 2b or 3 was achieved in 18 of 20 (90%) treated vessels, and 16 patients showed immediate restoration of flow after stent deployment. The mean number of passes for maximal recanalization was 1.4, and the median (quartiles) time from groin puncture to recanalization was 50 (38-71) minutes. No case required adjuvant therapy after deployment of the embolectomy device. No significant procedural events occurred. Symptomatic intracranial hemorrhage was found in 2 (10%) patients, 4 (20%) patients died during the 90-day follow-up period, and 45% of patients showed good functional outcome at 3 months (modified Rankin Scale score <or=2).

CONCLUSIONS

These results suggest that the Solitaire AB device can rapidly, safely, and effectively retrieve clots from the middle cerebral artery and terminus internal carotid artery within 8 hours from symptoms onset.

Idiopathic lingual artery aneurysm: CT findings and endovascular therapy. A case report

SUMMARY

We describe a 65-year-old woman with an asymptomatic idiopathic lingual artery aneurysm which is suspected to be congenital. We review the literature on external carotid artery branch aneurysms, diagnostic evaluation and discuss treatment options for the various types and the specific chosen in the case presented.

Upper limb ischaemia - a single centre experience

INTRODUCTION

This paper reviews the epidemiology, aetiology and management of upper limb ischaemia in a series of 8 patients presenting to a tertiary referral centre over a 4-year period and the review of the pertinent literature.

MATERIALS AND METHODS

Details of patients admitted to Tan Tock Seng Hospital (TTSH) due to critical ischaemia of the upper limbs were obtained from admission summaries through the Computerised Patient Support System (CPSS) and operative notes through LOTUS.

RESULTS

There were 8 patients who presented with upper limb ischaemia excluding trauma and iatrogenic causes over the last 4 years. All patients underwent embolectomy. One patient had an amputation post-embolectomy. Our short-term results were encouraging with 7 patients who were well enough to be discharged. One patient had a massive brainstem stroke and was discharged home for comfort care at the request of the family.

CONCLUSION

Careful physical examination and history taking, prompt recognition of upper limb ischaemia and active approach to management in the form of embolectomy are crucial in obtaining a good outcome and reducing the risk of late disabling effects.

Percutaneous interventions for pulmonary embolism

Venous thromboembolism and pulmonary embolism (PE) is the third most common cardiovascular disease and a leading cause of death in the US. There are many risk factors related to PE. Traditional treatments are anticoagulation, systemic thrombolysis, and surgical thrombectomy. More recently, several minimally invasive procedures were introduced, which includes catheter-directed thrombolysis, percutaneous embolectomy, embolus fragmentation techniques, pulmonary artery stent placement or association of two or more of those techniques. In the present study the Authors review the role of the different techniques for the treatment of PE, and provide some guidelines and indications for treatment. The most popular devices and techniques are described in detail, and the efficacy of the techniques is discussed.

Acute [corrected] stroke thrombolysis: an update [corrected]

Acute stroke therapy took a major step forward in 1996 after the approval of Intravenous (IV) tissue plasminogen activator (t-PA) by the US Food and Drug Administration for patients presenting within 3 hours of the onset of stroke symptoms. Since that time, there have been considerable advances in imaging techniques as well as the advent of devices to help in the management of acute stroke patients. As a result, the arsenal to treat acute stroke has grown, and the field of stroke as a subspecialty of neurology has emerged. Despite these advances, only 3% to 8% of eligible patients with acute stroke in the United States are administered thrombolytics.(1) We herein review the use of thrombolytics in stroke and provide an overview of the imaging advances, new devices, and recent trials that are shaping modern stroke therapy. Finally, we provide a practical approach to the management of acute stroke, specifically for the practicing cardiologist, who may encounter stroke during cardiac catheterization, post myocardial infarction (MI), and in a variety of other settings.

Endovascular reperfusion therapy in acute ischaemic stroke

OBJECTIVES

Endovascular reperfusion therapy in acute ischaemic stroke comprises a number of pharmacological and mechanical procedures. Mechanical embolectomy offers the promise of efficacious treatment for patients in whom pharmacological thrombolysis is contraindicated or might be ineffective. The purpose of this review is to outline endovascular reperfusion therapy in acute ischaemic stroke with focus on mechanical embolectomy.

MATERIALS & METHODS

Data on endovascular reperfusion therapy were acquired through searches in MEDLINE 1990-2006 by cross referencing relevant key words.

RESULTS

Mechanical embolectomy works well on large-volume proximal occlusions for which there was previously no effective treatment. Early safety trials are promising, efficacy in terms of recanalisation is substantial, and both safety and efficacy is expected to improve with further advances in technology.

CONCLUSIONS

Intravenous thrombolysis with tPA revolutionised acute stroke treatment a decade ago. Endovascular reperfusion therapy now offers the promise of a second revolution, expanding the number of patients eligible and the time window open for specific stroke treatment.

Embolectomy in a rabbit acute arterial occlusion model using a novel electromechanical extraction device

A prototype endovascular electromechanical clot-extraction device was fabricated using a combination of shape memory polymer and shape memory nickel-titanium alloy (nitinol). Five embolic vascular occlusions were created in 4 rabbits by injecting thermally coagulated blood through a 4F catheter in the common carotid artery. Angiography immediately after clot injection showed complete or partial occlusion of the common carotid artery. Posttreatment angiography showed complete (2/5), partial (2/5), or no (1/5) restoration of blood flow.

Middle cerebral artery stenting for acute ischemic stroke after unsuccessful Merci retrieval

OBJECTIVE

Intracranial stenting has been used in the treatment of ischemic stroke caused by acute intracranial vessel occlusion after unsuccessful recanalization with the Merci retriever. We describe our early experience with this technique.

METHODS

Patients who had intra-arterial therapy for acute ischemic stroke with concomitant use of the retriever between February 1, 2005 and May 2, 2006 were identified from our endovascular database. Cases in which recanalization was not achieved with the retriever and in which stenting was attempted as a secondary means of mechanical recanalization were retrospectively reviewed.

RESULTS

Ten patients with unsuccessful Merci retrieval underwent intracranial stenting. The average admission National Institutes of Health Stroke Scale score was 16.4. Occlusions were located in the middle cerebral artery (six extended into M2 branches). Four patients received intra-arterial reteplase (two prestent, one preretriever and poststent, and one poststent). Eptifibatide was administered immediately before stenting in every patient. Successful recanalization (thrombolysis in myocardial infarction 2 or 3) was achieved in nine out of 10 patients. Complications included an extradural perforation with arteriovenous fistula. Six patients had intracranial hematoma and/or subarachnoid hemorrhage; there were four deaths. The six surviving patients experienced at least a 6-point National Institutes of Health Stroke Scale improvement at discharge, although only one had a modified Rankin Scale score of 2 or less.

CONCLUSION

Angiographic recanalization has been associated with improvement in clinical outcome after acute cerebral ischemia. Recanalization is not always achieved using the Merci retriever. We found that stenting after unsuccessful Merci retrieval resulted in a high rate of angiographic success. Further research into refining indications and optimizing outcome is warranted.

Catheter-tip embolectomy in the management of acute massive pulmonary embolism

Three catheter interventional techniques are currently available for removing or fragmenting pulmonary emboli: aspiration thrombectomy, fragmentation, and rheolytic thrombectomy. The investigators systematically reviewed all available published research related to the use of catheter-tip devices in patients with pulmonary emboli. Pooled data showed that clinical success with the Greenfield catheter occurred in 72 of 89 patients (81%) when used alone and in 19 of 19 patients (100%) when used in combination with thrombolytic agents. Fragmentation with standard catheters used alone (without thrombolytic agents) was reported in only 3 patients. Clinical success with standard angiographic catheters occurred in 15 of 21 patients (71%) when used in combination with systemic thrombolytic agents and in 115 of 121 patients (95%) when used with local infusions of thrombolytic agents. Data for the Amplatz catheter, the rheolytic Angiojet catheter, and the Hydrolyser catheter when used alone were sparse or absent. Clinical success when used in combination with thrombolytic agents occurred in 6 of 6 patients (100%) with the Amplatz catheter, in 20 of 23 patients (87%) with the Angiojet catheter, and in 19 of 20 patients (95%) with the Hydrolyser catheter. Minor bleeding at the insertion site among all patients, with and without thrombolytic agents, occurred in 29 of 348 patients (8%), and major bleeding at the insertion site occurred in 8 of 348 patients (2%). One patient experienced perforation of the right ventricle with the Greenfield catheter. None reported perforation of a pulmonary artery. In conclusion, all the devices analyzed in this study appear to be useful in the management of acute massive pulmonary emboli.

Experimental model evaluation of filter trapping after embolectomy using the Merci system: supplemental technique for Merci retrieval procedure

Examination of embolectomy using the Merci Retrieval System using experimental stroke models demonstrated that aspiration is not adequate to remove larger clots. The effectiveness of filter trapping was examined using the same models. A silicone model of the carotid artery system with model blood clot was incorporated in a laboratory pulsatile flow system. Embolectomy was performed using the Merci Retrieval System. Any clot not evacuated through the balloon guide catheter was trapped with a distal protection filter device developed for cervical stenting. The clot could not be sucked into the guide catheter by the recommended procedures in nine of 15 trials. Trapping failed in only one trial, in which the clot passed through a gap between the edge of the filter orifice and the inner model lumen. A clot was withdrawn to the catheter tip trapped across the edge of the orifice frame in one trial, and a very large clot was trapped across the filter orifice in two trials. Even clots made by the same method showed variation in properties, especially hardness, which may affect the effectiveness of aspiration. The aspiration procedure recommended for the Merci Retrieval System did not remove the large clots formed by embolectomy. The trapping procedure using a filter device without an orifice frame was effective to solve this problem.

Preclinical testing of a new clot-retrieving wire device using polyvinyl alcohol hydrogel vascular models

INTRODUCTION

Cerebral embolism is the principal cause of cerebral infarction. Recently, mechanical embolectomy has been proposed as an effective method. We performed a preclinical evaluation of a new mechanical clot-retrieving wire.

METHODS

This clot-retrieving wire consisted of three nitinol loops at the tip of a microguidewire. These three loops could be collapsed into a 0.018-inch wire compatible microcatheter. Each loop was 8 mm long and 3.5 mm wide. For simulation, polyvinyl alcohol (PVA) vascular anatomical models of the human carotid (eight models) and vertebrobasilar (three models) circulation were constructed. A pulsatile flow circulation system was used. Embolic clots were produced using pig blood plasma. The microcatheter and the microguidewire were advanced beyond the clot. The wire was then exchanged for the retrieving wire. The microcatheter was then pulled slightly back to open the loops. The clot was then caught by withdrawal of the system. Once caught, the clot was retrieved to the guiding catheter tip. We investigated the following points: ease of device deployment, clot capture ability, clot removal against blood flow and removal of the clot out of the introducer system.

RESULTS

A total of 104 procedures were performed in 11 PVA models and evaluated. The drop rate was 19%. We succeeded in partial and total recanalization in 51.0% of the procedures (53/104) within 30 minutes.

CONCLUSION

This new clot-retrieving wire could be useful for mechanical clot extraction in stroke.

Endovascular mechanical clot retrieval in a broad ischemic stroke cohort

BACKGROUND AND PURPOSE

Our aim was to describe an expanded experience with endovascular mechanical embolectomy in a broad group of patients, including those not meeting entry criteria for the MERCI multicenter trials.

METHODS

We performed an analysis of all patients with ischemic stroke treated with the Merci Clot Retrieval Device at a single academic center outside of the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) trials.

RESULTS

Twenty-four patients were treated with the device. Nine were MERCI trial ineligible: 4 received intravenous (IV) tissue plasminogen activator (tPA), 1 received IV tPA and was younger than 18 years of age, and 4 had time-to-treatment of longer than 8 hours. Mean age was 64 years (range, 14-89 years; 42% women). Median National Institutes of Health Stroke Scale (NIHSS) score was 21 (range, 11-30). Median symptoms-to-procedure-start time was 303 minutes (range, 85-2385 minutes). Recanalization (Thrombolysis in Myocardial Infarction, 2-3) was achieved in 15/24 (63%). In device-only patients, recanalization occurred in 10/16. In patients who failed IV tPA undergoing rescue embolectomy, recanalization was achieved in 4/5. Three patients unresponsive to device therapy received rescue intra-arterial tPA/abciximab; recanalization was achieved in 2/3. Recanalization was achieved in 3/4 patients in whom treatment was started longer than 8 hours after symptom onset. Asymptomatic hemorrhage occurred in 38%; symptomatic hemorrhage, in 8%. Three device fractures occurred; none worsened clinical outcome. In-hospital mortality was 17%; 90-day mortality, 29%. Good 90-day functional outcome (modified Rankin Scale, <or=2) was achieved by 25% (6/24).

CONCLUSIONS

Endovascular mechanical embolectomy is an effective means of achieving revascularization in patients with acute ischemic stroke, including patients with late treatment start and intravenous tPA failure. Device-based therapy achieved recanalization in nearly two thirds of patients and good clinical outcomes in one fourth, with symptomatic hemorrhage in less than one tenth.

Merci Retriever in acute stroke treatment

The Merci Retriever is a device used for mechanical clot extraction in cerebral arteries. It obtained US FDA clearance in August 2004 for recanalization of cerebral arteries in acute stroke. Previously, intravenous recombinant tissue plasminogen activator administered within 3 h from symptom onset was the only other FDA-approved treatment in acute stroke. Stroke from large brain artery occlusion, which has the highest morbidity and mortality rate, is inefficiently treated with intravenous recombinant tissue plasminogen activator and has a high likelihood of hemorrhagic complication. In the multicenter prospective Mechanical Embolus Removal in Cerebral Ischemia trial that led to FDA clearance, the Merci Retriever achieved 48% vessel recanalization when used within 8 h of stroke onset, and resulted in lower morbidity and mortality in revascularized patients. Clinical efficacy trials are needed to determine the place of this device in the treatment of stroke patients.

Evaluation of Merci Retriever by Experimental Modeling

The Merci Retriever is the first device for mechanical embolus removal in patients with cerebral ischemia. Use of the device was evaluated using experimental models. Three stroke model systems were created: silicone embolism model with flow system, pig embolism model, and silicone-pig tortuous artery model. The series of extraction procedures (capture, retrieval, and aspiration) was examined in the models under flow control. Coagulated blood clot was adopted as embolic material, to simulate embolic stroke of the carotid or middle cerebral arteries. Retrieval of the clot was successful in only one of six trials in the silicone model of the carotid artery, as the clot easily worked free from the helical tip. Aspiration was successful in three of the six trials. Retrieval was successful in two of four trials in the middle cerebral artery and aspiration was successful in two. Retrieval was successful in all five trials in the pig embolism model, and three of five trials in the silicone-pig tortuous artery model. The Merci Retriever does not always retain the embolism, and the helix tends to distort in acute or rough lumen. Aspiration is not always successful.

Catheter-based recanalization techniques for acute ischemic stroke

Recent advances in endovascular interventional therapies have revolutionized the management of acute ischemic stroke. For patients who present with occluded circle of Willis vessels, timely and successful arterial recanalization is the best predictor of clinical improvement. Diagnostic neuroimaging has advanced noninvasive tools--namely, transcranial Doppler, CT angiography, and MR angiography--to screen individuals with acute neurologic syndromes rapidly for arterial occlusion, and hence to exclude from treatment those who are unlikely to benefit from or could be harmed by arterial recanalization strategies. Intra-arterial thrombolysis has been proven to be of benefit in large clinical trials. Moreover, the US Food and Drug Administration has recently approved the use of a mechanical clot retrieval device for acute embolic stroke, and a number of other similar strategies are under various stages of investigation. This article reviews the diagnostic and interventional approach to the management of large vessel embolic stroke.

AngioJet rheolytic thrombectomy versus local intrapulmonary thrombolysis in massive pulmonary embolism: a retrospective data analysis

PURPOSE

To compare the efficacy of full-dose local intrapulmonary thrombolysis (LIT) versus AngioJet rheolytic thrombectomy (ART) in the treatment of massive pulmonary embolism.

METHODS

A retrospective review was conducted of 8 consecutive patients (5 women; mean age 66.0+/-5.9 years, range 56-74) who underwent LIT with high-dose intrapulmonary urokinase (4400 IU/kg over 10 minutes followed by a 2000-IU/kg/h infusion) and a subsequent 6 consecutive patients (4 men; mean age of 59.2+/-17.0 years, range 26-69) who underwent ART plus adjunctive low-dose urokinase infusions (100,000 IU) until hemodynamic recovery was achieved. Pre and postprocedural Miller scores were calculated, and relative Miller score improvement, total urokinase doses, and duration of therapy were compared.

RESULTS

Hemodynamic stability was restored in all 8 LIT patients and in 5 (83%) of the 6 ART patients; 1 (16.7%) patient died during the ART procedure due to recurrent MPE. In the LIT group, the mean Miller score prior to intervention was 17.38+/-2.67, which was reduced to 6.13+/-1.46 after the intervention (p<0.0001) compared to scores of 18.83+/-2.86 and 6.83+/-2.79, respectively, in the ART group (p<0.0001). The mean urokinase dose was 2.07+/-0.44 million IU in the LIT group versus 0.70+/-0.36 million IU in the ART group (p<0.0001). The mean duration of therapy was 11.45+/-2.94 hours in the LIT group versus 3.37+/-1.41 hours in the ART group (p<0.0001). No significant difference in relative Miller score improvement was observed.

CONCLUSION

By accelerating the fragmentation of thrombus, ART plus adjunctive low-dose urokinase seems to be more rapidly effective compared to LIT. ART achieves both rapid cardiovascular relief and reduces the dose of thrombolytic agent necessary in patients with massive pulmonary embolism.

Mechanical Embolectomy

Mechanical embolectomy in acute ischemic stroke employs the use of novel endovascular devices to revascularize occluded intracerebral arteries. Devices like the Merci Retiever and other endovascular snares, laser thrombectomy and rheolytic/obliterative microcatheters, intracranial balloon angioplasty and stenting, and intra-arterial and transcranial ultrasound-enhanced chemical thrombolysis are intended to improve tissue rescue and diminish reperfusion hemorrhage while broadening the population eligible for therapy. Patient selection with MRI- and CT-based stroke protocols can detect tissue at risk and may obviate the classic limitations of the stroke therapeutic time window. These devices are being developed and modified at a rapid pace, requiring mounting endovascular expertise, and are being used successfully alone or in conjunction with chemical thrombolysis with relative safety.

The Incidence of Emboli during Cardiac Surgery: A Histopathologic Analysis of 2297 Patients

OBJECTIVE

Manipulation of the atherosclerotic aorta during cardiac surgery is assumed to cause embolization, which can contribute to adverse outcomes. Recently, as a result of worldwide trials deploying the Embol-X intraaortic filter during cardiac surgery, such emboli were captured and processed for histopathologic analysis.

METHODS

Filters with a pore size of 120 microns were placed in 2297 patients who underwent the following operations: coronary artery bypass grafting (CABG) (70%), valve (17%), combination CABG/valve (11%), and other (2%).

RESULTS

The filters captured at least one embolus in 98% of the patients. An average of 8.3 particles was captured per filter (range of 0-74). The surface area of the emboli was on an average 5.8 mm2 (range of 0-188 mm2). Histologic analysis of the captured particles indicated that in 79% of the filters fibrous atheromata were noted, in 44% there were platelets and fibrin, 8% had red blood cell thrombus, 3% had fibro-fatty/adventitial tissue, 2% had other material including cartilage, myocardium, lung, suture, and a teflon pledget. Of the patients enrolled, 1569 were high-risk. The average number of particles captured in the high-risk patients was 8.5 versus 5.8 for the low- to moderate-risk patients (P < .0001). Concomitantly,there was an increase in the embolic burden between the higher- and lower-risk patients (surface area 6.6 vs. 4.0 mm2, P < .0001).

CONCLUSION

These data show the ubiquitous incidence of emboli during cardiac procedures. Intraaortic filtration should reduce adverse outcomes as was demonstrated for the high-risk patients in this study. Aortic manipulation during cardiac surgery can cause embolization and increase morbidity. The use of an intraaortic filter can decrease the embolic burden. We now report the histopathologic analysis of these emboli.

[Treatment of acute myocardial infarction due to embolism by a thromboaspiration catheter]

Although rare, coronary embolism poses a therapeutic problem. Thromboaspiration is an elegant alternative to implantation of a stent. The place of stenting in acute myocardial infarction depends on the results of randomised trials. The authors report the case of a 69 year old woman who presented with an apico-lateral infarction probably due to a coronary embolism after postoperative thrombosis of a mechanical mitral valve prosthesis. The authors performed a percutaneous revascularisation by thromboaspiration with a good result.

MERCI 1: a phase 1 study of Mechanical Embolus Removal in Cerebral Ischemia

BACKGROUND AND PURPOSE

To report the result of the Mechanical Embolus Removal in Cerebral Ischemia (MERCI) 1 study, a phase 1 trial to evaluate the safety and efficacy of mechanical embolectomy in the cerebral vasculature.

METHODS

MERCI 1 enrolled 30 patients in 7 US centers. Main inclusion criteria were: National Institutes of Health Stroke Scale score (NIHSS) > or =10; treatment performed within 8 hours from symptoms onset and contra-indication to intravenous thrombolysis; no large hypodensity on computed tomography; and occlusion of a major cerebral artery on the angiogram. Safety was defined by the absence of vascular injury or symptomatic intracranial hemorrhage. Efficacy was assessed by recanalization rate and clinical outcome at 1 month. Significant recovery was defined as 30-day modified Rankin of 0 to 2 in patients with baseline NIHSS 10 to 20 and 30-day modified Rankin of 0 to 3 in patients with baseline NIHSS >20. The procedures were performed with the Merci Retrieval System, a system specially designed for intracranial embolectomy.

RESULTS

Twenty-eight patients were treated. Median NIHSS was 22. Median time from onset to completion of treatment was 6 hours and 15 minutes. Successful recanalization with mechanical embolectomy only was achieved in 12 (43%) patients, and with additional intra-arterial tissue plasminogen activator in 18 (64%) patients. There was one procedure related technical complication, with no clinical consequence. Twelve asymptomatic and no symptomatic intracranial hemorrhages occurred. At 1 month, 9 of 8 revascularized patients and 0 of 10 nonrevascularized patients had achieved significant recovery.

CONCLUSIONS

This phase 1 study shows that cerebral embolectomy with the Merci Retriever was safe and that successful recanalization could benefit a significant number of patients, even when performed in an extended 8-hour time window.

Thrombectomy for Acute Internal Carotid Thrombosis: Five Thrombectomy Devices Compared

OBJECTIVE

To test the safety and efficiency of commercially available thrombectomy catheters in clearing simulated internal carotid artery (ICA) thrombosis.

DESIGN

Comparative in vitro study.

MATERIALS AND METHODS

A model of the ICA was filled with human thrombus, the 'circle of Willis' back pressure was set at either 10 or 30 cm of water. Five thrombectomy devices (Hydrolyser, Clot Buster, Acolysis System, AngioJet and Fogarty embolectomy catheter) were compared for (i) efficiency at removing thrombus, (ii) pressure changes at the tip of each device, and (iii) distal embolisation by flow cytometry.

RESULTS

Thrombus clearance was greatest with the AngioJet (median 95%, range 92-97%) and least with the Acolysis System (median 34%, range 12-50%). The Clot Buster and Hydrolyser were safest as they produced only negative tip pressures, the AngioJet and Balloon catheter produced positive and negative pressures risking distal embolisation. The Acolysis system produced no pressure change during use. Distal embolisation (of particles between 5 and 40 microm diameter) was greatest with the Fogarty balloon catheter at 10 cm water (P<0.05) and least with the Hydrolyser and Clot Buster.

CONCLUSION

Balloon embolectomy for ICA thrombosis risks further embolic cerebral damage. The Hydrolyser and the Clot Buster show the greatest promise for ICA thrombectomy.

An update on bronchial blockers during lung separation techniques in adults

Techniques for one-lung ventilation (OLV) can be accomplished in two ways: The first involves the use of a double-lumen endotracheal tube (DLT). The second involves blockade of a mainstem bronchus (bronchial blockers). Bronchial blockade technology is on the rise, and in some specific clinical situations (e.g., management of the difficult airway during OLV or selective lobar blockade) it can offer more as an alternative to achieve OLV in adults. Special emphasis on newer information for the use of Fogarty embolectomy catheter as a bronchial blocker, the torque control blocker Univent, and the wire-guided endobronchial blocker (Arndt blocker) is included. Also this review describes placement, positioning, complications, ventilation modalities, and airflow resistances of all three bronchial blockers. Finally, the bronchial blockers can be used in many cases that require OLV, taking into consideration that bronchial blockers require longer time for placement, assisted suction to expedite lung collapse, and the use of fiberoptic bronchoscopy. The current use of bronchial blockers, supported by scientific evidence, dictates that bronchial blockers should be available in any service that performs lung separation techniques.

Fluoroscopy-assisted dual-catheter thromboembolectomy: a new technique useful in patients with embolization to arteries of disproportionate diameters

Distal embolization is a complication of aortoiliac aneurysm repair. Fluoroscopy-assisted catheter thromboembolectomy is useful in removing popliteal and tibial emboli from the femoral approach. Concomitant presence of aortoiliac and popliteal aneurysms, a known association, may present a difficult challenge to embolus extraction. Currently available embolectomy catheters large enough for thrombus extraction from a popliteal aneurysm are too large for safe tibial artery cannulation, and tibial balloon catheters cannot be enlarged sufficiently to transfer the thrombus through the aneurysmal popliteal segment. We treated a patient who embolized to his popliteal aneurysm and distal tibial circulation following aortoiliac aneurysm repair. A fluoroscopy-assisted dual-catheter technique was used to extract the thrombus through the femoral approach, eliminating the need for direct popliteal or tibial exploration. This technique uses two balloon catheters of graduated size, maneuvered concurrently under fluoroscopic guidance into the tibial and popliteal circulation. The smaller tibial catheter is inflated, and thrombus is withdrawn into the popliteal segment. The larger popliteal balloon catheter is then inflated distal to the smaller catheter, and both catheters are withdrawn simultaneously to deliver the clot through the femoral arteriotomy. This technique can be useful for successful balloon catheter extraction of thrombus via remote access, in an arterial system with variable diameter, eliminating the need for direct popliteal or tibial exploration.

Peripheral arterial applications of percutaneous mechanical thrombectomy

Various devices have been introduced for the purpose of percutaneous mechanical thrombectomy (PMT). These devices show promise as a valuable treatment option in acute arterial thrombotic occlusions, in addition to the gold-standard surgical method, the Fogarty balloon embolectomy, and local fibrinolysis therapy. Local fibrinolytic therapy cannot be used in the presence of contraindications, and can be time-consuming in limb threatening situations. Surgical intervention can also result in intimal vessel wall injury and is of limited value in infrageniculate occlusions. In this review, currently available PMT devices for peripheral arterial applications will be introduced, and their advantages, drawbacks and finally the reported clinical experience with these devices will be presented.

Treatment of basilar artery embolism with a mechanical extraction device: necessity of flow reversal

BACKGROUND AND PURPOSE

The success of local fibrinolysis in vertebrobasilar thromboembolism depends on the volume and composition of the clot. Since thrombolysis can also be time consuming and cause bleeding, we investigated the feasibility of a mechanical clot retraction device based on a nitinol basket advanced through a microcatheter.

METHODS

Five patients with acute embolism of the basilar artery who presented with progressive stroke and impaired consciousness were included in a multicenter study (Neuronet Evaluation in Embolic Stroke Disease [NEED]). In 3 patients flow reversal was induced with the use of silicone balloons or coaxial catheters. Three patients required additional fibrinolysis.

RESULTS

The device failed to retrieve the clots in our first 2 patients with distal basilar artery embolism. After successful recanalization by local fibrinolysis, both patients survived, 1 disabled and 1 with little residual impairment. In the next 3 patients the anterograde flow in the basilar artery was reversed during the short retraction period by temporarily blocking the vertebral or subclavian arteries. Two of these patients were completely recanalized by solely mechanical means; the third patient needed additional fibrinolysis before also being recanalized. All 3 patients survived: 1 remained disabled, 1 had almost a full recovery, and 1 became asymptomatic the day after the procedure.

CONCLUSIONS

Mechanical thrombus extraction seems to be a feasible method for preventing infarction by rapid, complete, and safe recanalization of the basilar artery. We recommend the use of flow control to support retrieval of the thrombus (which the proximal flow would otherwise keep in place like a cork) and to protect the distal vessels from embolization by fragments.

[Thrombectomy and embolectomy using the adherent clot catheter]

The efficacy of the Adherent Cloth Catheter is demonstrated on the three above described cases. The different mechanism of function on contrary to the classic Fogarty Catheter enables us to remove the older, strongly adherent thrombus from prothesis, artery or vein. The catheter is a functional instrument not only for vascular surgery, but also for invasive angiology.

Acute ischemia of the upper extremity: long-term results following thrombembolectomy with the Fogarty catheter

OBJECTIVE

In 1962, the procedure of arterial thrombembolectomy with the Fogarty catheter was established. Numerous studies have been published studying thrombembolectomies of the lower extremities. Limited information, however, is available following thrombembolectomy of the upper extremity after arterial occlusion. The aim of the present study, therefore, was to determine long-term results (3-5 years after thrombembolectomy) following thrombembolectomy of the upper extremity with the Fogarty catheter in a large retrospective clinical study.

DESIGN

In the present study, 251 patients were encountered. Over a period of 20 years, 283 thrombembolectomies with the Fogarty catheter were performed on the upper extremity at the surgical department of the University of Munich.

MAIN OUTCOME MEASUREMENTS

The appearance of local and general complications in the postoperative phase, as well as long-term results, were evaluated.

RESULTS

The results indicate that general complications - i.e., cardiac insufficiency, cerebral ischemia, etc. - occurred in 18 patients (7.2%). Local complications - i.e., wound infection, persistence of ischemia, or hematoma - were evident in 51 patients (20.3%). Re-occlusion following thrombembolectomy was found in 21 patients (8.8%). The affected extremity had to be amputated in five cases (2.0%), and 14 patients (5.6%) died during the postoperative phase. As a result of multimorbidity of the patients and average age at the time of surgery (73 years), 40% of the patients had died before the date of examination. Nonetheless, 111 patients of the 117 living patients showed no complaints or minor coldness and pain following heavy exercise.

CONCLUSIONS

The results of the present study indicate that, in most cases, thrombembolectomy with the Fogarty catheter represents a successful surgical method for the acute treatment of arterial occlusion of the upper extremity.

Comparison of three mechanical thrombus removal devices in thrombosed canine iliac arteries

PURPOSE

To assess and compare intimal and medial vascular damage caused by three mechanical wall-contact thrombectomy devices: Fogarty embolectomy catheter, Arrow-Trerotola peripheral thrombectomy device, and MTI-Castañeda over-the-wire brush.

MATERIALS AND METHODS

Bilateral external iliac arteries of 15 canines were thrombosed before mechanical thrombolysis. Ten thrombosed arteries were randomly assigned to receive each device. Animals were sacrificed immediately, and histologic assessment of endothelial and medial damage in the vessels was performed.

RESULTS

The vascular damage found with all devices extended into the tunica media. The Fogarty embolectomy catheter and the Arrow-Trerotola device caused significantly more damage than the Castañeda brush.

CONCLUSION

All devices caused lesions extending into the media. Previous research has shown that the extent and depth of the vascular lesion may be contributing factors in promoting early atherosclerotic and accelerated hyperplastic intimal and medial changes. These findings warrant further study of these devices in an atherosclerotic model with longer follow-up.

Transvenous Catheter Embolectomy

Transvenous pulmonary embolectomy was first described in 1969 by Greenfield and associates who designed a special catheter for the aspiration of thrombi in the pulmonary circulatory system. This technique was applied in 64 patients with massive pulmonary embolism (PE) with a 70 to 72% survival rate. However, it is difficult to implement and has not gained widespread acceptance. More recently, several other catheter devices have been used in patients with PE. The total number of patients reported does not exceed 100. Relative angiographic improvement varies between 10 and 49%, but hemodynamic improvement is not observed or not measured in most patients and mortality varies between 9 and 30%. Fibrinolysis was associated with mechanical thrombectomy in 54% of the patients, making the results difficult to interpret. Transvenous pulmonary embolectomy remains an experimental procedure and should been attempted only in the very few patients with PE, uncontrolled cardiogenic shock, and absolute contraindication to fibrinolytic treatment. Animal models are required to compare the different devices available.

Transcatheter snare removal of acute middle cerebral artery thromboembolism: technical case report

OBJECTIVE AND IMPORTANCE

We describe the case of a patient in whom a snare designed for the removal of foreign bodies was successfully used to retrieve a thromboembolism from the middle cerebral artery. This technique can be used to reestablish blood flow when maximal pharmacological therapies have failed.

CLINICAL PRESENTATION

A 38-year-old man with scrotal squamous cell carcinoma presented with the abrupt onset of left hemiparesis and numbness. Computed tomography of the head showed no hemorrhage or hypodensity, and right middle cerebral artery thrombosis was suspected.

INTERVENTION

Cerebral angiography demonstrated a near-total occlusion of the right middle cerebral artery at the M1-M2 junction. The administration of intra-arterial urokinase, systemic heparin, and systemic abciximab, and mechanical maceration failed to lyse the clot. A 4-mm goose-neck snare was guided through a microcatheter, and the clot was snared and withdrawn. Immediate postoperative angiography demonstrated the reconstitution of normal flow. Pathological examination of the snared material was consistent with clot. By postoperative Day 5, the patient had regained full strength, except for the fingers of the left hand, which remained moderately weak. Computed tomography demonstrated a right insular and extreme capsular infarct.

CONCLUSION

To our knowledge, this is the first reported use of a snare to remove clot in the setting of thromboembolic stroke. As the use of intra-arterial thrombolysis increases, transcatheter snare removal of pharmacologically resistant clot may be considered as a salvage strategy.