A 45-year-old man with no contributory medical history presented with tachycardia, tachypnea, and hypoxemia. Computed tomography angiography demonstrated a massive pulmonary embolism (PE) with saddle emboli and cardiac strain with RV/LV ratio of 1.02. Ultrasound also revealed extensive deep vein thrombosis (DVT) of the left lower extremity.
PE or DVT with heavy clot burden carries significant risk, and standard of care includes anticoagulation, systemic thrombolysis, or catheter-directed thrombolysis. The case herein demonstrates how the FDA-approved mechanical thrombectomy devices (FlowTriever and ClotTriever) are alternative and innovative treatments for PEs and DVTs, respectively. These devices are capable of retrieving clots that are too large for standard thrombectomy catheters.
The FlowTriever was used to extract a clot that extended from the bifurcation of the main pulmonary artery to the bilateral pulmonary arteries, and to the lower lobar and segmental arteries. The device was advanced directly into the thrombus, where three expandable disks were deployed to disrupt the clot. The aspiration catheter was used to remove the disks, as well as the newly fragmented thrombi. There were 780 cc of blood and clots retrieved, and the most sizable thrombus measured
11 × 1.5 cm. The ClotTriever was used for the DVT, and post-procedure venogram showed optimally restored flow without the need for thrombolytics.
FlowTriever and ClotTriever can be utilized for patients who have a contraindication to fibrinolysis, have not had clot resolution despite medical therapy, and are not candidates for surgical thrombectomy. The FlowTriever and ClotTriever approach can resolve clot burden without the risks and complications associated with thrombolytic agents.
Key words: FlowTriever, ClotTriever, pulmonary embolism, deep venous thromboembolism
The prevalence of pulmonary embolism (PE)-associated deep venous thromboembolism (DVT) has been intensely studied and widely discussed in the literature. A meta-analysis from 1998 found concomitant DVT ranging anywhere from 10% to 93% in different PE studies, with a pooled estimate of 36%.1 More recent meta-analyses have shown a higher prevalence of concomitant DVT, with one publication reporting an overall occurrence of 56%,2 and another a rate of 70.6% in 428 consecutive PE patients who had been specifically screened for the disease.3 It is possible that the higher reported rates in recent years might be a consequence of greater physician awareness of concomitant DVT in general, and/or improved diagnostic algorithms and optimized triage efforts in certain institutions.
Importantly, one of the meta-analyses found that a parallel DVT diagnosis conferred an almost doubled risk for early mortality in PE.2 This association in a large patient set supports the idea that optimizing treatment for both presentations of venous thromboembolism (VTE) might be vital. This idea is further supported by research showing that approximately 90% of symptomatic PEs originate from venous clots of the lower extremities.4 Therefore, addressing a DVT present in an acute PE patient should lower the risk of PE recurrence. Of note, and in line with the prognostic value regarding mortality, DVT diagnosis has been suggested to optimize PE risk stratification by identifying patients who might require advanced treatment.5, 6
We present a case of both parallel VTE presentations that was treated with mechanical thrombectomy, using uniquely designated PE and DVT catheters. The patient, a 45-year-old man, presented to the emergency department (ED) with persistent dyspnea. He had a medical history of asthma and intravenous (IV) drug abuse, and he had visited the ED with comparable symptoms two days ago. At his earlier visit, he was discharged with treatment for asthma, as his acute disease presentation was assumed to be an exacerbation of his chronic condition. However, during the subsequent ED visit, he mentioned that sinus congestion, fever, chills, and non-productive cough had initially started two weeks ago. While some symptoms eventually resolved, his cough, dyspnea, and mild wheezing persisted, which prompted the additional ED visit. Dyspnea was present upon exertion, and he also reported orthopnea, while denying any history of chest pain, pressure, palpitation, or lightheadedness. As the patient had also stated that he had been active, with no recent travel or immobilization, there was no apparent cause for a potential VTE. The patient denied any occurrence of heart disease or spontaneous VTE in his history, or in his family history, though he reported that his mother had a history of cancer-related DVT.
During the initial evaluation, the patient was found to be hypoxic at 87% saturation on room air, which improved once he was placed on 2 L oxygen via nasal cannula. Additional diagnostic work-up revealed that he was tachycardic, with a heart rate of 110-120 beats/min, and tachypneic, with a respiratory rate of 24-28 breaths/min. Electrocardiogram (ECG) showed non-specific T wave changes in the inferior leads, but a chest x-ray was negative for any acute process, and further laboratory tests revealed elevated brain natriuretic peptide and D-dimer levels (1,291 pg/mL and 2,756 ng/mL D-DU, respectively) and elevated creatinine (1.5 mg/dL).
Further investigation included a nuclear perfusion study (V/Q scan), which is a two-part measurement assessing ventilation (V) and perfusion (Q) of the lung. The nuclear perfusion study relies on scintigraphy and medical isotopes to evaluate the circulation of air and blood within the lung, and a mismatch of those measurements can be suggestive of PE. We confirmed a significant V/Q mismatch in the patient (Figure 1), so he was started on an IV heparin drip to prepare him for PE intervention that was planned for the following morning.
The next day, the patient underwent computed tomography imaging and chest pulmonary angiography that confirmed the presence of an extensive PE. The patient had a large, acute saddle PE at the pulmonary artery (PA) bifurcation, which extended into both the left and right main PAs, as well as into most of the lower lobar and segmental PA branches bilaterally (Figure 2). In addition, imaging indicated right ventricular (RV) strain with a calculated RV/left ventricular (LV) ratio of 1.02, above the 0.9 clinically-relevant cutoff.7,8 The calculated PE severity index score was 95. We also performed venous Doppler ultrasound of both legs, and we diagnosed acute DVT in the entire system of the popliteal, posterior tibial, and gastrocnemius veins.
As a result of the patient’s symptoms, extensive clot burden, concomitant DVT, and unfavorable RV/LV ratio, we planned for right heart catheterization to allow for mechanical aspiration thrombectomy of the PAs with the FlowTriever Triever20 (T20) catheter (Inari Medical), which has been shown to be safe and effective in patients with acute, intermediate-risk PE.9 Right femoral vein access was achieved, and an angled pigtail catheter was tracked over a wire into the main PA. The T20 catheter was delivered via a 22 French (F) DrySeal sheath (Gore Medical), tracking over an .035-inch Amplatz Super Stiff guidewire (Boston Scientific). The T20 mechanism of action relies on controlled aspiration. The distal end of the catheter is positioned in the affected PA segment, adjacent to the clot. Next, a vacuum is manually created by pulling back a
60 cc, custom, large bore syringe that is attached to a side port tubing connector at the sheath. Once the vacuum is established, it can be released, extracting the thrombus via powerful suction through the T20 catheter into the syringe. We successfully extracted the large PE thrombus burden from the right and left main PAs in this patient, and post-PA angiography confirmed restored perfusion. The patient reported immediate improvement in respiration while still on the table. No thrombolytics were required for this procedure.
However, a post-thrombectomy ECG was suggestive of cardiomyopathy, and showed an ejection fraction of 30% to 35%, moderate to severe LV dysfunction, global hypokinesia, and mild concentric LV hypertrophy with an RV systolic pressure of 42.1 mm Hg. We had already diagnosed the presence of concomitant DVT via Doppler ultrasound, so we performed a lower extremity venogram the next day, which confirmed extensive DVT from the left common femoral vein reaching into the lower extremity below the knee. Because further embolization could be detrimental to the already compromised heart, we elected to remove the remaining proximal DVT.
We performed thrombectomy of the DVT using the ClotTriever device (Inari Medical), and balloon angioplasty of the left popliteal vein. The ClotTriever device comes with two components, a 13 F specialty sheath with an integrated funnel to ensure optimal clot capture, and the ClotTriever catheter. Left popliteal access was achieved, and the ClotTriever catheter was inserted through the ClotTriever sheath over a .035-inch guidewire and advanced beyond the thrombus. Once positioned, the ClotTriever catheter was unsheathed to deploy a coring element with an attached collection bag. The coring element functions by gaining wall apposition after it is manually deployed, in order to separate the clot from the vessel wall. Cored thrombus is collected in the integrated collection bag as the catheter is slowly pulled back towards the sheath. After initial pullback is completed, the catheter is collapsed and removed from the body. Once outside the sheath, collected clot is removed to prepare the device for another run. We were successful in extracting large amounts of organized clot via three ClotTriever pullbacks (Figure 3). A post-procedure venogram showed optimally restored flow without the need for thrombolytics.
Although the thrombotic obstruction was fully cleared, stenosis of the left common femoral vein and left external iliac vein, possibly indicative of May-Thurner syndrome, became apparent on intravascular ultrasound. As the patient had undergone back-to-back PE and DVT thrombectomy, we elected to place him on anticoagulation for now, and consider a stent placement in a future session. The patient tolerated both thrombectomy procedures well and was discharged on apixaban 10 mg every 12 hours for the first week post procedure, with plans to switch to 5 mg every 12 hours thereafter. Due to the newly diagnosed cardiomyopathy, and his likely diagnosis of May-Thurner syndrome, he was recommended for follow-up as an outpatient.
Four days after his discharge, the patient returned to the ED with complaints of increasing leg pain that he described as cramping and swelling in his left calf. He reported no respiratory issues. Doppler ultrasound was repeated and confirmed a recurrent acute DVT in the mid to distal femoral vein, also involving the popliteal, proximal tibial, gastroepiploic, and soleus veins of the left lower extremity. We planned for a repeated left lower extremity venogram and ClotTriever thrombectomy, this time followed by external iliac vein stent placement to treat the compression as the likely underlying cause of his recurrence. We also switched the anticoagulation regimen from apixaban to warfarin, with enoxaparin used as a bridge. After the compression was addressed, no further re-intervention was needed. No additional PE has occurred, and the patient has recovered nicely.
A patient with newly diagnosed cardiomyopathy presented with concomitant PE and DVT, a common and clinically relevant finding in PE, which conferred a higher mortality risk. We were successfully able to treat this patient. First, we extracted an extensive bilateral and saddle PE via the FlowTriever system in a single session. The patient tolerated the procedure well, reported an immediate improvement in respiration while still on the table, and had no respiratory problems five days post intervention. We were able to address the DVT the following day with the ClotTriever catheter, removing a significant amount of organized thrombus and fully restoring flow. Both procedures were performed without the use of thrombolytics, avoiding a possible 9.2% associated risk of major bleeding and 1.5% risk of intracranial hemorrhage.10
The patient was initially diagnosed with acute PE using a V/Q scan. V/Q scans, in addition to their value for PE diagnosis, can also reliably confirm the presence of residual pulmonary vascular obstruction after PE treatment, which has been associated with a multitude of adverse outcomes in patients.11-15 A V/Q scan is also useful in detecting chronic thromboembolic pulmonary hypertension,16 another potential consequence of residual clot following an acute PE. A growing body of evidence shows that residual clots have detrimental effects on long-term patient outcomes, and concomitant DVT confers an additional recurrence risk in PE. Given this evidence of risk, it was especially vital that we treated both presentations of VTE and aimed to remove the maximum amount of thrombus.
Due to the presence of May-Thurner compression, the patient required a repeated intervention with the ClotTriever catheter. The repeated intervention highlights the importance of adequately addressing potential underlying physiologic causes of venous thrombus in affected patients. Having two dedicated VTE devices at hand allowed us to treat both the PE and concomitant DVT effectively and restore flow without the need for thrombolytic therapy and the associated major bleeding risk.
Disclosure: The authors report no financial relationships or conflicts of interest regarding the content herein.
Manuscript submitted July 1, 2019; manuscript accepted, September 10, 2019.
Address for correspondence: Tanaz Salimnia, MD, Wayne State University School of Medicine, Ascension Providence Rochester Hospital, Department of Cardiology, Rochester, Michigan. Email: firstname.lastname@example.org
Acknowledgements: The authors would like to acknowledge Craig D. Markovitz, PhD, and Maureen Ostaf, PhD for their contributions to the preparation of the manuscript.
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