Comparison of a new recirculation thrombectomy catheter with other devices of the same type: in vitro and in vivo evaluations

Molecular magnetic resonance imaging of deep vein thrombosis using a fibrin-targeted contrast agent: a feasibility study

PURPOSE

To evaluate the value of a fibrin-specific MR contrast agent (EP-2104R; EPIX Pharmaceuticals) for detection of deep vein thrombosis (DVT) and monitoring of percutaneous intervention for treatment.

MATERIALS AND METHODS

In 6 domestic swine, DVT was induced in an iliac/femoral vein using an occlusion-balloon catheter and subsequent injection of thrombin. The occluded vessels were recanalized by mechanical thrombectomy using a Fogarty catheter and an Arrow rotating thrombectomy device. Magnetic resonance imaging of the pelvis and lung was repeated 4 times (before and after DVT induction, after contrast agent administration, and after intervention) using a 1.5-T whole-body XMR system (ACS-NT, Philips Medical Systems, Best, NL). The visualization of the thrombi and contrast-to-noise ratio (CNR) was assessed.

RESULTS

EP-2104R allowed selective visualization of thrombi with accurate determination of the extent of DVT with high contrast (CNR: 65.3 +/- 17.2). After intervention, dislodged thrombus fragments were selectively visualized in the lung (CNR: 27.9 +/- 9.3).

CONCLUSIONS

Molecular magnetic resonance imaging using fibrin-specific MR contrast agent EP-2104R allowed for selective visualization of DVT and monitoring of percutaneous intervention.

A porcine deep vein thrombosis model for magnetic resonance-guided monitoring of different thrombectomy procedures

PURPOSE

To establish a porcine model of deep iliac vein thrombosis, which allows monitoring of thrombectomy and thrombolytic procedures by magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Deep iliac vein thrombosis was induced in 12 domestic swine using an occlusion-balloon catheter and subsequent injection of thrombin distal to the occluded vessel site. Thrombosis induction was successfully achieved in all animals after 1 hour as verified by MRI. In addition, x-ray fluoroscopy was performed for comparison. Subsequently, thrombectomy was performed using a Fogarty catheter, an Arrow-Trerotola percutaneous thrombolytic device as well as electrical discharge-induced shock waves. The latter procedure was carried out with and without additional administration of Actilyse. MRI and x-ray fluoroscopy were repeated to monitor therapy.

RESULTS

After successful thrombosis induction within the deep iliac veins in all cases, thrombus material could be completely removed using the Fogarty catheter and the Arrow-Trerotola percutaneous thrombolytic device, whereas electrical discharge-induced shock wave failed to recanalize the occluded vessel even if additional Actilyse was administered. The actual burden of thrombotic material could be reliably visualized using MRI.

CONCLUSIONS

A porcine model of deep iliac vein thrombosis model is presented, which permits reliable visualization of thrombotic material. This model might be a useful tool to compare different thrombectomy devices or to evaluate the effectiveness of new thrombolytic approaches.

Comparison of AngioJet Rheolytic Pharmacomechanical Thrombectomy versus AngioJet Rheolytic Thrombectomy in a Porcine Peripheral Arterial Model

INTRODUCTION

Rheolytic thrombectomy using the AngioJet catheter for arterial thrombosis has been shown to be effective in restoring blood flow. Additional infusion of thrombolytic agents via the AngioJet catheter results in combined rheolytic pharmacomechanical thrombolysis (PMT), which further enhances thrombectomy efficacy. However, the histologic response to rheolytic PMT therapy remains unclear. This study compares the acute and chronic vessel wall response and hemolysis due to conventional AngioJet rheolytic thrombectomy (RT) and AngioJet PMT in the porcine peripheral arterial model.

METHODS

A total of 19 juvenile pigs were divided into acute and chronic groups. In the acute group (n = 6), bilateral common carotid, femoral, and iliac arteries ranging from 3 to 6 mm in diameter were randomized to the control RT group or to PMT therapy. Vessels were analyzed 4 days following interventions. In the chronic group (n = 5), bilateral common carotid, femoral, and iliac arteries ranging from 3 to 6 mm in diameter were randomized to the control RT group or to PMT therapy. Vessels were analyzed at 30 days following interventions. Hemolytic evaluation was performed in additional eight pigs, which were randomized to either RT or PMT intervention.

RESULTS

In the acute group, similar histologic injury grades were noted between the RT- and PMT-treated femoral and iliac vessels. Endothelial denudation in the RT and PMT vessels were 43% and 39% (NS), respectively. Vessels with intact internal elastic lamina (IEL) in the RT and PMT groups were 54% and 57% (NS), respectively. In vessels < 4 mm in diameter, fractured IEL in the AT and PMT groups occurred in 23% and 27% (NS), respectively. The degrees of smooth muscle cell (SMC) loss were similar for the RT- and PMT-treated vessels (45% and 40%, respectively; NS). In the chronic group, no differences were seen between the RT and PMT groups with respect to endothelial denudation, IEL fracture rate, or SMC loss. Similar degrees of medial thickening or intimal hyperplasia were noted in the RT and PMT groups (49% and 43%, respectively; NS). No difference in hemolytic effect was noted in the treatment groups.

CONCLUSIONS

AngioJet rheolytic pharmacomechanical thrombectomy treatment incurs an equivalent safety profile in medium-caliber peripheral arteries when compared to rheolytic thrombectomy treatment. No difference in hemolytic reaction occurred in either group. The observed clinical efficacy of rheolytic pharmacomechanical thrombectomy does not result in untoward vessel injury compared to conventional rheolytic thrombectomy therapy.

How thrombus model impacts the in vitro study of interventional thrombectomy procedures

RATIONALE AND OBJECTIVES

Numerous experimental models are used to investigate the effectiveness of thrombectomy devices. We aimed to study the systematic effects of different in vitro thrombus models on the results of experimental thrombectomy and examined how thrombi formed in vitro and ex vivo differ.

METHODS

Three variables involved in human in vitro thrombogenesis were investigated: spontaneous or thrombin-induced clotting, age (1 or 5 days old), and storage temperature (4 degrees C or 21 degrees C). The fibrin content of in vitro and fresh or old ex vivo thrombi was measured by histologic studies. Ten experiments were performed with each of 8 different in vitro thrombus types using (1) ultrasound thrombolysis, (2) Oasis thrombectomy, (3) Amplatz thrombectomy, and (4) Straub-Rotarex catheters. Thrombus weight was measured after standardized treatment.

RESULTS

The fibrin content was markedly lower in all in vitro than in fresh and old ex vivo thrombi. In vitro thrombus type had no impact on the effectiveness of ultrasound thrombolysis and Amplatz thrombectomy. Thrombogenesis type affected Oasis and Straub-Rotarex catheter use. Storage temperature had a systematic impact on the outcome of Oasis thrombectomies.

CONCLUSION

The fibrin content of in vitro thrombi differs substantially from that of fresh and old ex vivo human thrombi. Experimental conditions may systematically impact experimental evaluation of thrombectomy procedures. In vitro thrombi with thrombin-induced thrombogenesis should be favored for use in thrombectomy experiments.

Noninvasive Extracorporeal Thrombolysis Using Electrical Discharge-Induced Shock Waves

RATIONALE AND OBJECTIVES

Many thrombectomy approaches have been developed for the treatment of venous thrombosis; however, no reference standard exists at this time. The aim of this study was to evaluate the efficacy of the transcutaneous application of electrical discharge-induced shock waves for thrombolysis in an in vitro model.

METHODS

Shock waves were applied on a thrombus positioned in a plasma-containing silicon tube using 2 different energy flux densities (0.53 and 2.26 mJ/mm). Depending upon the specific experiment, the thrombus was slightly moved to mimic pulsatory motions or/and additional Actilyse was added. Plasma samples were taken to determine the d-dimers before and after the application of shock waves.

RESULTS

Energy of 0.53 mJ/mm was insufficient for thrombolysis whereas the energy of 2.26 mJ/mm yielded a removal rate of up to 76.4% when the thrombus was slightly moved during the procedure. The amount of d-dimers correlated well with the addition of Actilyse. However, this did not affect the removal rate significantly.

CONCLUSION

The results demonstrate the potential of electrical discharge-induced shock waves for thrombolysis.

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.