Comparison of Aspiration Catheters with Modified Standard Catheters for Treatment of Large Pulmonary Embolism Using an In-vitro Patho-Physiological Model

Purpose The presented in-vitro study provides a comparison of various catheters for mechanical treatment of large-burden pulmonary embolism (PE) under standardized conditions, using a new test rig. Dedicated aspiration catheters (JETi®, Penumbra Indigo®, Aspirex®) were compared with standard catheters (Pigtail, Multi-Purpose, Balloon Catheter) applied for embolus fragmentation. Materials and Methods Emboli prepared from porcine blood were washed into the test rig which consists of anatomical models of the pulmonary artery (PA) and of the right heart in combination with a pulsatile drive system. For all catheters, the duration of the recanalization procedure and the weight percentage (wt%) of the remaining, removed and washed-down clot fractions were evaluated. For aspiration catheters, the aspirated volume was measured. Results All catheters achieved full or partial recanalization. The aspiration catheters showed a significantly (p < 0.05) lower procedure time (3:15 min ± 4:26 min) than the standard fragmentation catheters (7:19 min ± 4:40 min). The amount of thrombus removed by aspiration was significantly (p < 0.001) higher than that by fragmentation, averaging 86.1 wt% ± 15.6 wt% and 31.7 wt% ± 3.8 wt%, respectively. Nonetheless, most of the residue was fragmented into pieces of ≥ 1 mm and washed down. Only in 2 of 36 tests, a residual thrombus of 11.9 wt% ± 5.1 wt% remained in the central PA. Conclusion Comparison under standardized in-vitro patho-physiological conditions showed that embolus fragmentation with standard catheters is clearly inferior to aspiration with dedicated catheters in the treatment of large-burden PE, but can still achieve considerable success. Level of Evidence No level of evidence, experimental study.

Abstract 1122‐000072: Mechanical Thrombectomy for Cerebral Venous Sinus Thrombosis in the setting of APL

Introduction : 28 year‐old woman with newly diagnosed acute promyelocytic leukemia (APL) undergoing chemotherapy with tretinoin and arsenic trioxide developed new onset headache and binocular diplopia. Neurologic exam was significant for bilateral papilledema and bilateral abducens nerve palsies. MR venogram showed incomplete opacification of the right and left transverse sinuses consistent with thrombosis. Therapeutic dose enoxaparin was started and she was taken to the neuroangiography suite. Methods : The left internal jugular vein was catheterized, and the microcatheter was advanced to the opacified left sigmoid sinus. A stent retriever was then deployed and suction thrombectomy was performed, with improvement of the filling defect. Next, the right internal jugular vein was catheterized and the right sigmoid sinus was accessed. Suction thrombectomy was performed, but due to residual thrombus, a stent retriever was deployed in the right transverse sinus and suction thrombectomy was reattempted, with improved recanalization. Results : Patient returned to the unit and continued therapeutic enoxaparin. Three days post‐procedure, she developed worsening headache and syncope. She was again taken to neuroangiography suite and the RIJ vein was again catheterized. Venogram after advancing the catheter to the right sigmoid sinus showed multiple filling defects in the proximal right transverse sinus. The catheter was advanced to the sigmoid sinus and a stent retriever was introduced; multiple attempts were made to remove the thrombus. Follow‐up venogram showed significant improvement in recanalization. The LIJ vein was then catheterized and venogram was performed, showing worsening filling defect in the left sigmoid sinus. A stent retriever was deployed in the left transverse sinus and suction thrombectomy was performed, however there was still significant residual thrombus. Suction thrombectomy, another stent retriever attempt and finally balloon angioplasty were then performed with some improvement of patency.. Follow‐up CTV 5 days post‐procedure showed stable venous sinus filling defects. Patient reported gradual improvement of headaches and was transitioned to apixaban. On follow‐up evaluation 3 months post‐procedure, patient reported resolution of headaches and diplopia. Conclusions : CVST is generally treated with systemic anticoagulation based on data from two randomized trials, however, ISCVT showed that 13% still decline on anticoagulation. Data regarding the safety and efficacy of MT for CVST is lacking, as well as data regarding patient selection. Our initial decision to treat with MT was due to involvement of posterior fossa and signs of increased intracranial pressure, which are potential prognostic factors for clinical decline with anticoagulation alone from ISCVT. Our patient was initially treated with therapeutic enoxaparin, however developed neurologic deterioration, so she was taken back to the neuroangiography suite. This case report illustrates an example of successful utilization of endovascular therapy for CVST in a patient with acute neurologic deterioration, with good neurologic outcome following recanalization

Micro-CT-Based Quantification of Extracted Thrombus Burden Characteristics and Association With Angiographic Outcomes in Patients With ST-Elevation Myocardial Infarction: The QUEST-STEMI Study

Background: Angiographic detection of thrombus in STEMI is associated with adverse outcomes. However, routine thrombus aspiration failed to demonstrate the anticipated benefit. Hence, management of high coronary thrombus burden remains challenging. We sought to assess for the first time extracted thrombotic material characteristics utilizing micro-computed tomography (micro-CT).Methods: One hundred thirteen STEMI patients undergoing thrombus aspiration were enrolled. Micro-CT was undertaken to quantify retrieved thrombus volume, surface, and density. Correlation of these indices with angiographic and electrocardiographic outcomes was performed.Results: Mean aspirated thrombus volume, surface, and density (±standard deviation) were 15.71 ± 20.10 mm3, 302.89 ± 692.54 mm2, and 3139.04 ± 901.88 Hounsfield units, respectively. Aspirated volume and surface were significantly higher (p &lt; 0.001) in patients with higher angiographic thrombus burden. After multivariable analysis, independent predictors for thrombus volume were reference vessel diameter (RVD) (p = 0.011), right coronary artery (RCA) (p = 0.039), and smoking (p = 0.027), whereas RVD (p = 0.018) and RCA (p = 0.019) were predictive for thrombus surface. Thrombus volume and surface were independently associated with distal embolization (p = 0.007 and p = 0.028, respectively), no-reflow phenomenon (p = 0.002 and p = 0.006, respectively), and angiographically evident residual thrombus (p = 0.007 and p = 0.002, respectively). Higher thrombus density was correlated with worse pre-procedural TIMI flow (p &lt; 0.001). Patients with higher aspirated volume and surface developed less ST resolution (p = 0.042 and p = 0.023, respectively).Conclusions: Angiographic outcomes linked with worse prognosis were more frequent among patients with larger extracted thrombus. Despite retrieving larger thrombus load in these patients, current thrombectomy devices fail to deal with thrombotic material adequately. Further studies of novel thrombus aspiration technologies are warranted to improve patient outcomes.Clinical Trial Registration: QUEST-STEMI trial ClinicalTrials.gov number: NCT03429608 Date of registration: February 12, 2018. The study was prospectively registered.

Optical Coherence Tomography-Based Patient-Specific Residual Multi-Thrombus Coronary Plaque Models with Fluid-Structure Interaction for Better Treatment Decisions: A Biomechanical Modeling Case Study

Intracoronary thrombus from plaque erosion could cause fatal acute coronary syndrome (ACS). A conservative anti-thrombotic therapy has been proposed to treat ACS patients in lieu of stenting. It is speculated that the residual thrombus after aspiration thrombectomy would influence the prognosis of this treatment. However, biomechanical mechanisms affecting intracoronary thrombus remodeling and clinical outcome remain largely unknown. In vivo optical coherence tomography (OCT) data of a coronary plaque with two residual thrombi after anti-thrombotic therapy were acquired from an ACS patient with consent obtained. Three OCT-based FSI models with different thrombus volumes, fluid-only and structure-only models were constructed to simulate and compare the biomechanical interplay among blood flow, residual thrombus and vessel wall mimicking different clinical situations. Our results showed that residual thrombus would decrease coronary volumetric flow rate by 9.3%, but elevate wall shear stress (WSS) by 29.4% and 75.5% at Thrombus 1 & 2, respectively. WSS variations in a cardiac cycle from structure-only model were 12.1% and 13.5% higher at the two thrombus surfaces than those from FSI model. Intracoronary thrombi were subjected to compressive forces indicated by negative thrombus stress. Tandem intracoronary thrombus might influence coronary hemodynamics and solid mechanics differently. Computational modeling could be used to quantify biomechanical conditions under which patients could receive patient-specific treatment plan with optimized outcome after anti-thrombotic therapy. More patient studies with follow-up data are needed to continue the investigation and better understand mechanisms governing thrombus remodeling process.

Impacts on Thrombus and Chordae Willisii During Mechanical Thrombectomy in the Superior Sagittal Sinus

The anatomical structures of the superior sagittal sinus (SSS) are usually damaged during mechanical thrombectomy (MT), and MT procedure could lead to new thrombosis in the sinuses. However, the mechanism remains unclear. We aimed to investigate the risks of embolism and assess the damage to chordae willisii (CW)-associated MT using a stent passing across the thrombus. A contrast-enhanced in vitro model was used to mimick MT in the SSS. The thrombus was removed with a stent. The emboli generated during the procedure were collected and measured. The residual thrombus area after the MT was measured by J Image software. The damage of CW was evaluated by an endoscope. Three procedural experiments were carried out on each cadaveric sample. The average numbers of visible emboli particles in experiments 1, 2, and 3 were 11.17 ± 2.17, 9.00 ± 2.07, and 5.00 ± 2.96, respectively. The number of large size particles produced by experiment 1 was significantly higher than that of the other experiments. The thrombus area measured after experiment 3 was larger than that of experiments 1 and 2. The number of minor damage cases to CW was 55 (90.16%), and there were six serious damage cases (9.84%). The use of stent resulted in no significant increase in damage to CW after the three experimental procedures. A large amount of thrombi particles was produced during MT, and multiple MT procedures on the same sample can increase residual thrombus area. Moreover, the stent caused minor damages to the CW in SSS.

Optical coherence tomography imaging after endovascular thrombectomy for basilar artery occlusion: report of 3 cases

Studies evaluating individuals for endothelial injury after endovascular thrombectomy (EVT) have been done by means of retrieved human thrombus, MR vessel-wall imaging, and animal histopathological studies. These techniques have limitations, because MR imaging has insufficient spatial resolution to directly visualize endothelium, and histopathological examinations are performed ex vivo and are unable to provide real-time patterns of injury. The purpose of the current study was to obtain in vivo intraluminal imaging after EVT by using optical coherence tomography (OCT), examining for evidence of endothelial injury in real time.Three consecutive patients with acute basilar artery occlusion underwent OCT imaging immediately after EVT. There were no complications and adequate images were obtained for all patients. Anatomical features of the vessel wall were discernible, including intima, media, adventitia, and internal/external elastic lamina. Basilar artery thick concentric plaque fibrosis was present, causing outward remodeling and loss of the internal/external lamina in certain regions. Evidence of significant residual thrombus was also visible, with mostly red thrombus present despite complete angiographic revascularization. The residual thrombus was not visible on CT, MR, or cerebral angiography and could certainly cause ongoing function-limiting strokes with occlusion of adjacent vital basilar perforators after EVT.