Preclinical in vivo testing of a rotational mechanical thrombolytic device

Managing Arrow-Trerotola Percutaneous Thrombolytic Device Complications

Dialysis access interventions are frequently performed by interventional radiologists. Several commercially available percutaneous thrombolytic devices can help restore patency to thrombosed arteriovenous access circuits. The Arrow-Trerotola Percutaneous Thrombolytic Device is one such device, and has a long track record of safe and effective use. However, like any medical device, complications can occur during its use. This article describes three complications and associated management strategies utilizing fundamental interventional radiology techniques of balloon tamponade, stent placement, and snare mediated foreign body retrieval.

Vascular injury caused by mechanical thrombectomy in porcine arteries: AKónya eliminator device versus Arrow-Trerotola percutaneous thrombolytic device

PURPOSE

To compare vascular injuries induced by a nonrotational thrombectomy device equipped with an adjustable basket (the AKónya Eliminator [AKE] device) and the Arrow-Trerotola percutaneous thrombolytic device (PTD) in porcine external iliac arteries (EIAs).

MATERIALS AND METHODS

The EIAs of nine domestic pigs underwent simulated thrombectomy with the AKE after the diameter of the basket had been adjusted to the vessel's diameter and with the PTD after motor activation. Three animals were euthanized immediately after treatment (group 1, acute), three after 1 week (group 2, subchronic), and three after 6 weeks (group 3, chronic). Vessel diameters were measured angiographically at four anatomic locations at the three time points. A histologic grading system was established to quantify the degree of vascular injury and lumen compromise. Four other EIAs were treated with an "oversized" AKE basket and followed for 6 weeks.

RESULTS

Histologically, the acute lesions in the AKE-treated vessels were more superficial than those in the PTD-treated vessels. In group 2, two of three PTD-treated arteries occluded, and their subchronic injuries were more serious than those in the AKE-treated arteries. In group 3, all AKE-treated arteries remained patent, but one of the PTD-treated vessels occluded, and the lumen sizes of the PTD- and AKE-treated arteries differed significantly. After 6 weeks, there was no significant difference between arteries treated with the PTD and those treated with the oversized AKE in terms of diameter or histologic grading.

CONCLUSIONS

The adjustable basket and hand-controlled operation of the AKE were significantly less injurious to the arterial wall than the constant-size PTD basket operated at 3,000 rpm. Damage produced by the oversized AKE basket was similar to that produced by the PTD.

Percutaneous Venous Thrombectomy Using the Arrow-Trerotola Percutaneous Thrombolytic Device (PTD) with Temporary Caval Filtration: In Vitro Investigations

PURPOSE

To evaluate the size and quantity of downstream emboli after thrombectomy using the Arrow-Trerotola Percutaneous Thrombolytic Device (PTD) with or without temporary filtration for extensive iliofemoral and iliocaval thrombi in an in vitro flow model.

METHODS

Iliocaval thrombi were simulated by clotted bovine blood in a flow model (semilucent silicone tubings, diameter 12-16 mm). Five experimental set-ups were performed 10 times each; thrombus particles and distribution were measured in the effluent. First, after retrograde insertion, mechanical thrombectomy was performed using the PTD alone. Then a modified self-expanding tulip-shaped temporary vena cava stent filter was inserted additionally at the beginning of each declotting procedure and removed immediately after the intervention without any manipulation within or at the filter itself. In a third step, the filter was filled with thrombus only. Here, two experiments were performed: Careful closure within the flow circuit without any additional fragmentation procedure and running the PTD within the filter lumen, respectively. In the final set-up, mechanical thrombectomy was performed within the thrombus-filled tubing as well as in the filter lumen. The latter was closed at the end of the procedure and both devices were removed from the flow circuit.

RESULTS

Running the PTD in the flow circuit without filter protection led to a fragmentation of 67.9% (+/-7.14%) of the clot into particles < or =500 microm; restoration of flow was established in all cases. Additional placement of the filter safely allowed maceration of 82.9% (+/-5.59%) of the thrombus. Controlled closure of the thrombus-filled filter within the flow circuit without additional mechanical treatment broke up 75.2% (+/-10.49%), while additional mechanical thrombectomy by running the PTD within the occluded filter led to dissolution of 90.4% (+/-3.99%) of the initial clot. In the final set-up, an overall fragmentation rate of 99.6% (+/-0.44%) was achieved.

CONCLUSIONS

The combined use of the Arrow-Trerotola PTD and a temporary vena cava stent filter proved to be effective for even large clot removal in this experimental set-up.

Applications of percutaneous mechanical thrombectomy in pulmonary embolism

Percutaneous mechanical thrombectomy (PMT) has matured into a reliable and valuable therapeutic tool in acute vascular diseases. PMT devices are designed to achieve rapid clearance of acute occlusion in large arteries and veins. This article provides a summary of cumulated experience on pulmonary embolism (PE) treatment with PMT devices. PMT devices are a heterogeneous group of devices that uses different forms of energy. Most of the devices do not totally eliminate thrombus rather fragment in small particles. The rationale of PMT is based on the rapid relief of central pulmonary obstruction. PMT in massive PE provides efficacious and safe debulking of centrally located thrombus in PE, lowering pulmonary artery pressures and improving hemodynamics and blood oxygenation. This results in lowering mortality if compared with natural history of PE, and reduced procedure time if compared with pharmacological thrombolysis. The clinical indications for percutaneous intervention in PE are discussed in the text.

Low-power transverse ultrasonic treatment of portal vein thrombosis in an animal model

PURPOSE

The authors have recently developed a small-diameter, thin, flexible ultrasonic catheter device that permits the removal of thrombus by low-power transverse ultrasonic cavitation energy. In this study, the authors sought to determine whether this device could be used to eliminate portal vein thrombosis in an animal model.

MATERIALS AND METHODS

In five anesthetized pigs, a total of six occlusions of the left portal vein were achieved with use of autologous clot with (n = 2) or without (n = 4) thrombin injection (250 U) introduced via a 7-F transhepatic catheter/sheath system. Angiographic examination documented complete occlusion of this vessel. The 75-cm-long, 21-gauge ultrasonic catheter (Resolution) was introduced into the clot under angiographic guidance via the transhepatic sheath. Transverse-wave ultrasonic energy was then delivered from the distal 5 cm of the probe at 3.5 W +/- 10% power for up to 6 minutes. Repeat angiographic studies were performed to document patency. After the procedure, gross and histopathologic examinations were performed.

RESULTS

Restoration of patency of the main left portal vein was documented in all cases at angiography, with no evidence of residual clot fragments in the major branches. However, side branches demonstrated small thrombotic plugs on pathologic examination. No complications such as perforation of the vessel adjacent to the active ultrasonic tip were encountered. Virtually all thrombolysis was documented to occur within the first minute of energy application. At gross pathologic examination, there was no evidence of damage to the portal vein, and histopathologic examination demonstrated minimal intimal disruption without damage to the media.

CONCLUSIONS

This preliminary animal study suggests the feasibility of a percutaneous transhepatic approach to the treatment of portal vein thrombosis with use of low-power ultrasonic cavitation energy. With further study, this method may have potential for the treatment of thrombotic disease, thereby offering novel therapy to patients with thrombotic vascular occlusions.

Current options in the diagnosis and management of acute limb ischemia

Acute limb ischemia occurs due to a sudden decrease in the blood flow to a limb, resulting in a potential threat to the viability of the extremity. Unfortunately, the threat is not only to the limb, but these patients are also at high risk for death. Limb hypoperfusion results in systemic acid-base and electrolyte abnormalities that impair cardiopulmonary and renal function. Successful reperfusion may result in the release of highly toxic free radicals, further compromising these critically ill patients. Therapeutic choices are often few and patient expectations are not always realistic. The management of acute limb ischemia requires a thorough understanding of the anatomy of the arterial occlusion and the open surgical and percutaneous options for restoring limb perfusion. Priorities for the diagnosis and effective management of these critically ill patients are provided.

Prototype percutaneous thrombolytic device: preclinical testing in subacute inferior vena caval thrombosis in a pig model

PURPOSE

To develop an animal model of subacute inferior vena caval (IVC) thrombosis and apply this model in evaluating the safety and efficacy of a prototype percutaneous thrombolytic device for restoring patency.

MATERIALS AND METHODS

In 11 pigs, a stent with a ligature in the middle was placed in the IVC. Thrombin was injected to induce thrombosis. Hemostasis was achieved by using an occlusion balloon. The stent was ligated to prevent thrombus migration. Five to 8 days after thrombus induction, the ligature was broken and the stent fully deployed. In 10 animals, thrombectomy was performed by using the percutaneous thrombolytic device. A vena caval filter was inserted at the beginning of each declotting procedure. Thrombus removal percentage was estimated and pulmonary angiograms obtained to detect embolism before and after thrombectomy. The IVC was analyzed histologically. To determine thrombus composition, one animal was sacrificed without thrombectomy. Concerning procedural safety, failure of the stent delivery system, stent migration, and venous perforation due to balloon inflation and the stent placement or thrombectomy procedure were evaluated.

RESULTS

Thrombus creation was successful in all animals. Fragmentation led to 75%--100% thrombus removal with flow restoration in all cases. There were no episodes of stent delivery failure, stent migration, or venous perforation. No significant pulmonary embolism was observed. In one case, a vessel dissection was identified at histologic examination.

CONCLUSION

In this animal model of IVC thrombosis, the percutaneous thrombolytic device is effective and safe for clot removal.

Contemporary treatment of thrombosed hemodialysis grafts

Maintaining hemodialysis grafts remains a difficult problem. Before the early 1990s, graft declotting was usually performed in the surgical suite. Percutaneous declotting has been evolving since the mid-1980s. Initially, a low-dose thrombolytic infusion of streptokinase through a single catheter was used. Crossing catheters with a higher-dose infusion of urokinase was then introduced. This technique was modified with the adjunctive use of pharmacomechanical techniques with the use of compliant balloons and the adjunctive use of heparin. The advent of the "lyse-and-wait" technique provided a simpler and quicker way to declot thrombosed grafts by using urokinase, with similar outcomes. Since the removal of urokinase from the market, multiple mechanical devices have been used with similar success. Recent reports concerning the use of newer-generation thrombolytic agents report similar outcomes, with a reduction in total cost.

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.

The use of mechanical thrombectomy devices in the management of acute peripheral arterial occlusive disease

A number of percutaneous mechanical thrombectomy devices are currently being used or undergoing clinical evaluation for the treatment of acute and chronic limb-threatening ischemia. Preliminary studies on the safety, efficacy, and device limitations have spurred an interest in percutaneous techniques for thrombus debulking as stand-alone therapy or an adjunct to pharmacologic thrombolysis. The devices have various mechanisms or combinations of mechanisms to optimize thrombus removal. Efficacy of thrombus removal is balanced by the propensity for vessel wall damage and distal embolization, especially for wall-contact devices (Arrow-Trerotola device and Cragg and Castañeda brushes). Initial experience in hemodialysis graft occlusion has subsequently moved on to peripheral arterial occlusions. Although the U.S. Food and Drug Administration has approved eight mechanical thrombectomy devices (MTDs) for use in thrombosed hemodialysis grafts, only the AngioJet LF140 is currently approved for use in peripheral arterial occlusive disease. Nevertheless, numerous clinical articles and abstracts have reported the "off-label" use of MTDs in the management of limb-threatening ischemia. A description of the eight MTDs and a review of the current literature on use of MTDs for acute peripheral arterial occlusive disease are provided.

Massive pulmonary embolism: treatment with the hydrolyser thrombectomy catheter

PURPOSE

To assess the efficacy of clot removal with use of the Hydrolyser thrombectomy catheter in acute massive pulmonary embolism (PE).

MATERIALS AND METHODS

Eleven patients (eight women, three men) with a mean age of 61 (range, 37-79) years with acute massive PE underwent percutaneous mechanical thrombectomy (PMT) with use of the Hydrolyser. In four patients with no contraindication, fibrinolysis was performed with use of urokinase at low doses after thrombectomy.

RESULTS

Ten patients (90.91%) recovered from massive PE and were discharged within 11 days. The Urokinase Pulmonary Embolism Trial angiographic severity indexes (mean +/- SD) were 14.7 +/- 2.6 and 7.5 +/- 2.7, respectively, before and after thrombectomy (P < .001). Partial arterial pressures of O2 increased from 72.8 mm Hg +/- 16.4 to 93.5 mm Hg +/- 5.6 (P < .005). Pulmonary artery pressure decreased from 45.5 mm Hg +/- 14.2 to 29.5 mm Hg +/- 13.6 after thrombectomy (P < .0001). Calculated by semiquantitative computed analysis, PMT with use of the Hydrolyser removed 74.06% of thrombus +/- 13.46%. One patient developed self-limited hemoptysis immediately after thrombectomy. One patient died during the procedure secondary to PE.

CONCLUSION

PMT with use of the Hydrolyser is effective and safe in massive PE, resulting in improved hemodynamics and blood oxygenation and decreased pulmonary artery pressure. It offers an alternative to fibrinolysis and surgical thrombectomy.

Mechanical thrombolysis of thrombosed hemodialysis native fistulas with use of the Arrow-Trerotola percutaneous thrombolytic device: our preliminary experience

PURPOSE

To evaluate the feasibility of use of the Arrow-Trerotola percutaneous thrombolytic device (PTD) in the treatment of thrombosed hemodialysis native fistula occlusions.

MATERIALS AND METHODS

Ten patients with native fistula occlusion underwent mechanical thrombolysis with use of the PTD. The standard PTD was used in seven patients and the over-the-wire device was used in three patients. Major outcomes of our study included procedure time, clinical success, complication rate, and 3- and 6-month patency rates.

RESULTS

The technical success rate was 100% and the clinical success rate was 90% (9 of 10). In all 10 cases, the procedure was associated with angioplasty. There were no major complications. The mean time of successful procedures was 126.1 minutes. The 3- and 6-month primary patency rates were 70% and 60%, respectively; the assisted primary patency rate at 6 months was 80%.

CONCLUSION

The PTD is an effective mechanical device for percutaneous treatment of thrombosed hemodialysis access. Our clinically successful initial experience with the PTD shows that the technique is rapid and safe for treatment of native fistula occlusions.

Modified use of the arrow-trerotola percutaneous thrombolytic device for the treatment of thrombosed hemodialysis access grafts

PURPOSE

To assess the safety and efficacy of using the Arrow-Trerotola percutaneous thrombolytic device (PTD) as the sole means of mechanical thrombolysis in hemodialysis access grafts, including in situ treatment of the arterial plug.

PATIENTS AND METHODS

Fifty consecutive patients (22 women, 28 men; mean age, 58 years; mean graft age, 29 months), in whom mechanical thrombolysis of a thrombosed hemodialysis access graft using the PTD was planned, were included in the study. In all patients, the PTD was used to treat the arterial plug in situ at the arterial anastomosis, instead of using a Fogarty catheter to reposition the plug, as indicated in the PTD product labeling. Prospective data collection included demographic information, technical details of the procedure, immediate outcomes, and complications. Patients were followed for 3 months using definitions and data forms that were identical to those used in the original clinical trial of the PTD. A sample of procedures drawn from the PTD clinical trial database (n = 54) served as control.

RESULTS

Immediate technical patency was 100%. Complications included arterial embolization (6% versus 2% control; P = NS; all successfully treated with backbleeding); venous rupture (6% versus 2% control; P = NS); and sepsis (n = 1), probably due to occult graft infection. Adjunctive therapy with an Adherent Clot catheter was needed in two procedures (4%). Three month patency using life-table analysis was 42% (versus 39% control; P = NS). The number of subsequent interventions (surgical/percutaneous) to the arterial limb of the graft did not differ from the PTD trial, and no native arterial stenoses were detected during the follow-up period.

CONCLUSIONS

The PTD is safe and effective when used as the sole means of mechanical thrombolysis of hemodialysis grafts. Treating the arterial plug in situ with the PTD eliminates the need for a Fogarty or Adherent Clot catheter in 96% of procedures. A slight increase in arterial embolic complications was observed but these were easily treated with backbleeding.

Evaluation of a modified arrow-trerotola percutaneous thrombolytic device for treatment of acute pulmonary embolus in a canine model

PURPOSE

Massive pulmonary embolus (PE) is often rapidly fatal. Surgical thrombectomy has a mortality rate as high as 74%. Multiple percutaneous methods have been tested with limited success. The purpose of this study was to evaluate the Arrow-Trerotola percutaneous thrombolytic device (PTD) for (i) the ability to clear pulmonary embolus and (ii) the effect on normal pulmonary vasculature. These were tested in a canine model.

MATERIALS AND METHODS

Iatrogenic unilateral massive PEs were created in nine canines. These PEs were then treated with the PTD. The device was also activated in the normal pulmonary artery. Immediately after treatment, six animals were killed. Three animals were allowed to recover and underwent pulmonary arteriography 1 month later to evaluate pulmonary hypertension, stenosis, or occlusion; they were then killed. Autopsy specimens were evaluated for histologic evidence of acute or chronic vascular injury.

RESULTS

Acutely, the PTD effectively thrombolysed the PE in all animals. Histologically, there was moderate intimal injury, but no evidence of pulmonary artery disruption. There was one device failure. One month after treatment, there was no radiographic evidence of pulmonary stenosis at device activation sites, no pulmonary hypertension, and only mild histologic evidence of scar formation.

CONCLUSION

In preliminary animal testing, the PTD is safe and effective for treating large central pulmonary emboli. Human clinical trials are warranted.

New thrombolytic brush catheter in thrombosed polytetrafluoroethylene dialysis grafts: preclinical animal study

PURPOSE

To assess the safety, efficacy, endothelial changes, and risks of pulmonary embolic events after the use of a new thrombolytic brush catheter in mature thrombosed polytetrafluoroethylene (PTFE) dialysis grafts in an animal model.

MATERIALS AND METHODS

Loop configuration PTFE grafts were implanted in the femoral vessels of 12 canines 4 weeks before mechanical thrombosis was performed. The thrombus was allowed to consolidate for 24 hours in 10 animals, 72 hours in one animal, and 7 days in one animal. Standard percutaneous criss-cross catheter access was performed, and a soft, low-speed, brush (6 mm in diameter), aided by 250,000 U of periprocedural urokinase, was utilized for thrombolysis. The native vessels, just distal to the anastomosis, and lungs were evaluated macro- and microscopically.

RESULTS

Thrombolysis was complete in all grafts with the exception of a small segment between the crossing of the access vascular sheaths. The total thrombolysis time ranged from 8 to 12 minutes; this included 5 minutes of pulse-spray lacing. No difference in thrombolysis time was found with regard to the age or amount of thrombus. Minimal endothelial changes were noted and no evidence of acute pulmonary embolus was found on necropsy or histologic studies.

CONCLUSION

This method offers a simple, safe, and efficient means of recanalization of thrombosed PTFE dialysis grafts in this canine model.

Acute and delayed outcomes of mechanical thrombectomy with use of the steerable Amplatz thrombectomy device in a model of subacute inferior vena cava thrombosis

PURPOSE

To study the efficacy and delayed outcome of mechanical thrombectomy with the Amplatz thrombectomy device (ATD) in an experimental model of subacute inferior vena cava (IVC) thrombosis.

MATERIALS AND METHODS

Mechanical thrombectomy was performed in 23 dogs with subacute infrarenal IVC thrombosis (6-15 days old). Heparin was administered during thrombectomy in all procedures (activated clotting time > or = 300 sec). Thirteen animals were killed immediately after thrombectomy, and the remaining 10 were allowed to survive for up to 1 month with no anticoagulation therapy.

RESULTS

Venographic patency of the IVC was restored in all animals, although residual mural thrombus remained in nine dogs (< 20% narrowing in seven, 20%-30% narrowing in two). No histopathologic evidence of mechanical wall disruption attributed to mechanical thrombectomy was seen. However, foci of organizing residual thrombus with associated transmural phlebitic changes with round-cellular infiltration were present in all acute specimens, including those appearing clear at venography. Venography at 1 week or 1 month after thrombectomy showed IVC rethrombosis in eight dogs (80%) who were not receiving anticoagulants. During mechanical thrombectomy, a small increase in mean pulmonary artery pressure occurred, with a corresponding decrease in systemic arterial oxygen saturation. No acute emboli were noted on the post-thrombectomy pulmonary angiograms. However, histopathologic examination of acutely explanted lungs in 11 animals showed arteriolar microemboli (100-500 microm) in four.

CONCLUSION

Mechanical thrombectomy with use of the ATD can effectively clear subacute IVC thrombus. However, rethrombosis is common and may be due to the high prevalence of phlebitis and residual thrombus. Anticoagulation may need to be continued after successful thrombectomy to prevent progression of residual thrombus and allow mural phlebitic changes to subside.