A new thrombectomy catheter device (AngioJet) for the disruption of thrombi: An in vitro study

Angiojet System Used in the Treatment of Submassive Pulmonary Embolism: A Case Report of Two Patients

Background

Massive or submassive pulmonary embolism (PE) carries a high mortality. Percutaneous mechanical thrombectomy using the Angiojet system is accepted for the treatment of PE. Here, we reported two submassive PE cases who were treated with the Angiojet system successfully, to provide some advice for the therapy of submassive PE.

Method

Two patients with suffocation were admitted to our hospital. One patient was accompanied by lower blood pressure (20% lower than basal blood pressure) and higher pulmonary artery pressure (89 mmHg); the other patient had larger right ventricular transverse diameter (46 mm), decreased left ventricular end diastolic anteroposterior diameter (34 mm), and higher heartbeats (107 heartbeats per minute). Pulmonary artery computed tomography angiography showed bilateral pulmonary embolism.

Result

The Angiojet system with a high-pressure jet spray pattern (urokinase 25 wiu + sodium chloride injection 50 ml) was used. Intravascular thrombolysis by urokinase (100 wiu/day for 1 day) was done after being back in the ward. And low molecular weight heparin was used in hospitalization, and rivaroxaban was used after discharge. Both patients were treated successfully. However, the level of platelet was significantly lower in one patient after Angiojet system usage and recovered to the preoperative level the next day. Another patient suffered from bradyarrhythmias during the usage of Angiojet, and bradyarrhythmias disappeared when the Angiojet system stopped. Pulmonary embolism was cured after 3 months in both patients.

Conclusion

Angiojet could be a simple, safe, and well-tolerated treatment for massive or submassive PE. And hematocrit, platelet, kidney function, and heart rhythm should be monitored during perioperation.

Experimental Evaluation of the Effectiveness of Aspiration-Based Techniques to Treat Different Types of Acute Thromboembolic Occlusions in the Femoropopliteal Vascular System Using an In Vitro Flow Model

PURPOSE

In this in vitro study, the effectiveness and safety of four aspiration-based techniques for thrombectomy are evaluated for three types of thrombi in a flow model simulating the femoropopliteal segment.

MATERIAL AND METHODS

Red, white, and mixed thrombi were produced in a standardized manner and used to simulate occlusion of a superficial femoral artery using a pulsatile flow model. Four techniques were compared: aspiration alone, aspiration + stent retriever, exposing thrombus to laser by an excimer laser system and a laser catheter + aspiration, and aspiration + mechanical fragmentation by a separator. Rate of first-pass recanalization, embolic events, and number of embolized fragments > 1 mm were compared.

RESULTS

Aspiration alone, stent retriever, laser, and separator differed in rates of first-pass recanalization (53.3%; 86.6%; 20%; and 100%) and embolic events (40%; 93.3%; 73.3%; and 60%). Number of embolized fragments was lowest with aspiration and higher with separator, laser, and stent retriever. Rates of first-pass-recanalization (75%; 75%; and 45%) and embolic events (65%; 60%; and 75%) differed for red, white, and mixed thrombi. The mixed thrombus caused the highest number of embolized fragments, which was particularly high using the stent retriever.

CONCLUSION

Additional use of mechanical techniques significantly enhances the effectiveness of thrombectomy but simultaneously provokes more embolism. Laser seems to negatively alter the structure of a thrombus and thus diminishes the effectiveness, while provoking embolism. All techniques had lowest effectiveness, but highest embolism with the mixed thrombus. This was particularly striking when a stent retriever was used with the mixed thrombus.

For Whom the Bubble Grows: Physical Principles of Bubble Nucleation and Dynamics in Histotripsy Ultrasound Therapy

Histotripsy is a focused ultrasound therapy for non-invasive tissue ablation. Unlike thermally ablative forms of therapeutic ultrasound, histotripsy relies on the mechanical action of bubble clouds for tissue destruction. Although acoustic bubble activity is often characterized as chaotic, the short-duration histotripsy pulses produce a unique and consistent type of cavitation for tissue destruction. In this review, the action of histotripsy-induced bubbles is discussed. Sources of bubble nuclei are reviewed, and bubble activity over the course of single and multiple pulses is outlined. Recent innovations in terms of novel acoustic excitations, exogenous nuclei for targeted ablation and histotripsy-enhanced drug delivery and image guidance metrics are discussed. Finally, gaps in knowledge of the histotripsy process are highlighted, along with suggested means to expedite widespread clinical utilization of histotripsy.

Percutaneous rheolytic mechanical thrombectomy in thrombosed direct intrahepatic portosystemic shunt: Report of two cases

We report two patients with Budd-Chiari syndrome, who underwent direct intrahepatic portosystemic shunt complicated by shunt thrombosis. Percutaneous AngioJet mechanical thrombectomy in combination with manual catheter aspiration and balloon disruption of the residual clot was successful, restoring patency of the thrombosed shunt.

Experimental model of large pulmonary embolism employing controlled release of subacute caval thrombus in swine

PURPOSE

To develop a catheter-based model of large pulmonary embolism (PE) in swine based on in situ venous thrombus formation.

MATERIALS AND METHODS

Ten Yorkshire swine underwent transjugular implantation of a retrievable inferior vena cava (IVC) filter. A thrombin and collagen mixture was injected into a confined space created by two balloons inflated proximal and distal to the IVC filter. Animals were left to survive for 7 days ± 3 to allow thrombus to organize in situ. The caval thrombus was released on transcatheter retrieval of the IVC filter and embolized into the main and branch pulmonary arteries. The severity of PE was scored based on digital subtraction angiography with the Miller index. At necropsy, thrombi were recovered and analyzed histopathologically.

RESULTS

Large PE was induced in all animals (Miller index score of 15 ± 5). Two animals developed saddle embolus with bilateral pulmonary artery occlusion, and five developed proximal occlusion of the left or right pulmonary artery. Nevertheless, no animal exhibited significant hemodynamic compromise. Large tubular thrombi were explanted in the size range of 5-10 cm long and 0.5-1 cm wide. Histologic analysis indicated an organized thrombus with infiltration of white blood cells and fibrin deposition.

CONCLUSIONS

Large caval thrombi can be formed in vivo and released at a predetermined time to induce large PE in a large animal model. This may help in the development and testing of new therapeutic approaches for PE.

Coronary thrombectomy, technical comparison of two systems on a laboratory bench: the impact of bends, angles and thrombus age

AIMS

Despite the results of recent randomised studies, the systematic use of aspiration techniques in ST-elevation myocardial infarction has not been included in the new guidelines. To date, there have been very few bench tests of the different systems and the aim of our study was to test two catheters on different models of arteries with thrombi at six and 12 hours.

METHODS AND RESULTS

The test apparatus consisted of 3 mm diameter glass tubes of 150 mm in length. The thrombi were left for either six or 12 hours and ten models of tubes were used: straight, with a single bend and with two bends. Two types of catheters were tested: the Export® aspiration catheter (EAC) and the Proxis® embolic protection system (PES). The main assessment criterion was total thrombectomy. Total thrombectomy was achieved in only 55.3% of the tests and no difference appeared between the two systems. Total thrombectomy was achieved more frequently with 6-hour thrombi than with 12-hour thrombi for the two techniques, 62.5% vs. 42.5% (p = 0.018) and 67.5% vs. 48.7% (p = 0.025) for EAC and PES catheter, respectively. In contrast, total thrombectomy was more frequent in straight tubes and in tubes with a single bend than in tubes with double bends, respectively for EAC (64% vs. 44.8%, p = 0.028) and for PES (85.9% vs. 35.4%, p < 0.001).

CONCLUSIONS

The use of thrombectomy in the invasive management of acute coronary syndromes is growing. Our work on a "laboratory bench" reveals important technical differences. In consequence, in clinical practice, we speculate that the catheter system must be chosen according to both the artery anatomy and the delay between chest pain and PCI.

Large tube section is the key to successful coronary thrombus aspiration: Findings of a standardized bench test

Thrombus removal by aspiration is one of the adjunctive techniques used to avoid embolization during PCI for acute myocardial infarction. Numerous devices are now available, but little is known about the mechanical rationale used in comparing them. The aim of the present study was to determine parameters to obtain optimal thrombus aspiration (TA). Heparin- and antiplatelet-free blood samples were aspirated into 3 mm diameter standardized glass tubes to create a 30 mm long thrombus. Thrombus formation took place at room temperature over a period of 6 or 12 hr. Various catheters were tested using a variable vacuum device: three with right-angle distal tip (0.038'', 0.067'', and 0.070'') and one with a beveled distal (length of the beveled, 0.054''; inner diameter catheter, 0.040''). The single endpoint was complete thrombus aspiration. A total of 103 TAs were presented for the four catheters. For 6- or 12-hr-old thrombus for a given catheter, there was no significant difference in vacuum pressure required to succeed TA (P = 0.47). For 6- or 12-hr-old thrombus, the larger the contact area is, the lower the pressure needed to aspirate the thrombus. Moreover, a beveled distal tip length (0.054'') does not make it possible to succeed TA at a lower pressure. The main factor for successful TA for thrombi > or = 6 hr is inner diameter and not immediate thrombus contact area.

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.

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.

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

RATIONALE AND OBJECTIVES

To compare a new 7 Fr. Helix thrombectomy catheter with Amplatz thrombectomy devices (ATD) with respect to clot fragmentation efficiency, hemolytic potential, and risk for vascular trauma.

MATERIALS AND METHODS

Particle size was evaluated following the maceration of 8-to-10-day-old clots, each weighing 6 +/- 0.01 g. The clots were macerated using devices of various sizes, including the 7-Fr. Helix thrombectomy catheter, the 7-Fr. over-the-wire (OTW), 8-Fr. ATD and the 6-Fr. ATD. The number of particles by weight was quantified. The 7-Fr. Helix and the 8-Fr. ATD were tested in the native iliac vein of six dogs without presence of clots. Blood samples were obtained before, during, and at 1, 3, 6, 24, and 48 hours after the procedure, to monitor the hemolytic effects. The treated iliac veins were examined histologically.

RESULTS

Most of the clot was fragmented into particles <10 microm. The mean percentage by weight of the original clot that remained as particles larger than 10 microm was 1.59% in the 7-Fr. Helix group. This was significantly less than 3.10% with the 6-Fr. ATD, 2.57% with 7-Fr. OTW and 2.44% in the 8-Fr. ATD group (<0.01). In vivo results showed a higher plasma free hemoglobin (PFH) level starting 5 minutes after initiating the ATD activation, reaching its peak after completion of the activation, and declining afterward, with return to the baseline at 24 hours. The haptoglobin level tended to decline slightly at 10 minutes, reaching its lowest level at 24 hours, and starting to recover at 48 hours. A similar pattern of PFH and haptoglobin changes was found in both groups. There were no significant differences regarding hemolytic effect of the two tested devices. No significant changes of creatinine were observed for up to 48 hours after procedures. Focal microthrombosis was seen in two sites of two vessels treated with the 7-Fr. Helix and a focal injury of a venous valve was noted in the 8-Fr. ATD group. The media and internal elastic lamina (IEL) were intact in all cases.

CONCLUSION

The newly designed 7-Fr. Helix is more effective in fragmentation in vitro clots than the 6 Fr. ATD, 7-Fr. OTW and the 8-Fr. ATD. The 7-Fr. Helix and the 8-Fr. ATD produced hemolytic effects, but they appeared to be tolerated by the animals. The in vivo results indicated that the 7-Fr. Helix appears to be as safe as the 8-Fr. ATD.

Angiographic outcome after intracoronary X-Sizer helical atherectomy and thrombectomy: first use in humans

The objective of this study was to evaluate the early angiographic outcome in the first human subjects who underwent intracoronary atherectomy and thrombectomy using the X-Sizer helical cutting and aspiration system. Percutaneous coronary interventions in patients with thrombo-occlusive disease or friable degenerative saphenous vein grafts are associated with considerable periprocedural morbidity and mortality, predominantly related to microscopic distal embolization. X-Sizer catheter system is a novel atherectomy and thrombectomy device that consists of a helix cutter connected to a handheld motor drive unit and a vacuum collection chamber for aspiration of excised atheroma, thrombus, and debris. Quantitative coronary angiography was obtained in 14 patients before and after X-Sizer extraction atherectomy with adjunctive balloon angioplasty and stenting. Thirteen native coronary arteries and one saphenous vein graft were treated. Mean preprocedural reference vessel diameter was 3.06 +/- 0.66 mm. There were 71.4% AHA/ACC type B2 and C lesions. Preprocedural thrombus was present in nine patients and total occlusion in 64% of cases. Minimal luminal diameter was increased from 0.29 +/- 0.47 mm to 1.32 +/- 0.64 mm, a gain of 1.04 +/- 0.69 mm after atherectomy. Final total gain was 1.47 +/- 0.61 mm. Mean diameter stenosis was reduced from 89.3% to a final residual stenosis of 14.4%. Postatherectomy distal embolization occurred in one patient who had heavy preprocedural thrombus burden. No episodes of perforation, distal coronary spasm, abrupt closure, or slow/no-reflow occurred. The angiographic analysis of the first cohort of human subjects suggests that X-Sizer helical atherectomy is a feasible method of removing occlusive tissue or thrombus in coronary artery disease with a low angiographic complication rate. A large-scale randomized phase II clinical trial is underway to determine the ultimate safety and efficacy of this device in thrombo-occlusive native coronary arteries and saphenous vein grafts.