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Right Atrial Vacuum-Assisted Thrombectomy: Single-Center Experience
Abstract: Background. Right heart thrombus in the absence of structural heart disease, atrial fibrillation, or intracardiac catheter is rare. It typically represents a thrombus migrating from the venous system to the lung, known as thrombi-in-transit, and can lead to a life-threatening pulmonary embolism. The optimal therapy for thrombi-in-transit remains controversial. We report our experience using percutaneous removal of right heart thrombus using vacuum aspiration. Methods. Patients with right atrial mass who were hemodynamically stable and underwent vacuum thombectomy using the AngioVac system (AngioDynamics) at our institution were included in this analysis. Between December 2012 and August 2014, a total of 7 patients (2 men, 5 women) with a mean age of 51.5 years (range, 20-83 years) underwent right atrial thrombectomy. Data during the procedure and follow-up period were collected and analyzed. Results. All patients were hemodynamically stable before the procedure. The procedure was considered successful in 6 patients. All patients survived through hospitalization. No periprocedural bleeding, stroke, or myocardial infarction occurred. One patient developed cardiogenic shock after the procedure that required extracorporeal membrane oxygenation support for <24 hours. There was no recurrent venous thromboembolism at a mean follow-up of 9 months. Conclusion. Vacuum-assisted thrombectomy can be a potential treatment option for hemodynamically stable patients with large right-sided intracardiac thrombus who are not surgical candidates.
J INVASIVE CARDIOL 2016;28(5):196-201
Key words: percutaneous retrieval, right heart thrombus, suction cannula, AngioVac, pulmonary embolism
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Thrombi-in-transit represents a right heart thrombus that is traveling from the venous system to the lung.1 It is usually rare and can be life threatening, particularly when associated with pulmonary embolism (PE).2-4 The optimal therapy for thrombi-in-transit remains controversial. Retrospective studies indicate that PE patients with free-floating intracardiac thrombus are at the highest risk for mortality and have the greatest benefit from surgery, as opposed to treatment with anticoagulation alone.5,6 Furthermore, thrombolytic therapy has been described as a treatment modality; however, its use is somewhat limited due to the known risk of significant hemorrhage (overall 22%, with up to 3% intracranial hemorrhage) and suggested risk of distal embolization.5 The AngioVac cannula (AngioDynamics) has been approved by the United States Food and Drug Administration in 2009 for venous drainage during extracorporeal bypass for removal of soft thrombus or embolic material. A number of recent case reports have demonstrated its utility for vacuum thrombectomy in retrieval of material from the right heart.7-9 In this series, we report our experience using the AngioVac system for removal of right heart thrombus.
Methods
Study population. Between December 2012 and August 2014, patients with right atrial thrombus where vacuum-assisted thrombectomy was used at Lenox Hill Heart and Vascular Institute of New York-North Shore Long Island Jewish Health System were reviewed. The inclusion criteria were a thrombus in the right atrium and/or right ventricle diagnosed by echocardiography (Figure 1) and/or computed tomography scan (Figure 2) and systolic blood pressure ≥90 mm Hg in patients who were deemed not suitable for surgical thrombectomy. Procedures were performed as a collaborative effort between cardiology, cardiothoracic surgery, and cardiac anesthesia using the heart-team approach. Data collected from the medical records included demographic information, medical history, clinical presentation and indications, procedural variables, in-hospital outcomes, and follow-up.
System description. The AngioVac cannula is designed for the removal of undesirable intravascular material. It is a 22 Fr coil-reinforced cannula with a balloon-actuated, expandable, funnel-shaped distal tip that can be advanced percutaneously or via surgical cutdown coupled with a circuit and a filter. The cannula is connected to a circuit resembling a cardiopulmonary bypass system, where a pump generates suction, filters the blood, and returns it via reinfusion (inflow) cannula.
Procedure description. All procedures were performed under general anesthesia. The outflow cannula was inserted in the common femoral vein or the internal jugular vein; the femoral or internal jugular vein was punctured and serially dilated to accommodate a 26 Fr Gore DrySeal sheath (W.L. Gore & Associates). The 22 Fr AngioVac cannula and its dilator were inserted into the sheath over an Amplatz Super Stiff 0.035˝ wire (Cook Medical) and advanced to the right atrium under echocardiographic and fluoroscopic guidance (Figure 3).
Additional access in the contralateral common femoral vein was obtained and the reinfusion (inflow) cannula (16-20 Fr Fem Flex II; Edwards Lifesciences) was inserted. The AngioVac circuit was then completed with a filter to collect the aspirated thrombus. Priming and thorough de-airing were performed. Anticoagulation was maintained throughout with intravenous heparin titrated to an activated clotting time of >250 seconds. The extracorporeal circuit was then activated and blood circulated in a veno-venous fashion: blood was suctioned from the patient via the AngioVac cannula, circulated through a centrifugal pump with flow rates of 3 L/minute (2500-4000 rpm), then returned directly to the patient via the inflow cannula. The AngioVac cannula was placed close to the intravascular debris or clot and then repeatedly advanced and withdrawn to suction the thrombus (Figure 4).2,10 Hemodynamic status was monitored closely. Aspirant was collected in a filter trap and sent for cytologic and microbiologic analysis. At the case completion, vascular closure was achieved at both cannulation sites using a mattress technique.
Definitions. Procedure success occurred when: (1) the mass disappeared on transesophageal echocardiography without hemodynamic instability; and (2) there was a lack of major complications such as cardiac perforation, pericardial tamponade, cerebral vascular accident, or death. Shock was defined as low blood pressure requiring vasopressor to maintain the systolic blood pressure >90 mm Hg, submassive pulmonary embolism as presence of pulmonary embolism with systolic blood pressure ≥90 mm Hg and evidence of right heart strain and/or elevated troponin-T level, right heart strain as the presence of right ventricular dilatation or hypokinesis on transthoracic echocardiography, elevated troponin-T level as troponin-T level >0.01 ng/mL, and cerebrovascular accident (CVA) as a transient or permanent focal neurological deficit occurring after procedure. Bleeding was defined according to the Bleeding Academic Research Consortium (BARC) definition (Table 1).11
Results
The AngioVac system was used in 7 patients (2 men, 5 women) with a mean age of 51.5 years (range, 20-83 years) (Table 2). The clinical presentation was dyspnea (3/7), chest pain (1/7), and palpitation (5/7). Inferior vena cava mass, acute PE, and catheter-associated thrombus were present in (3/7), (2/7), and (2/7) of the cases, respectively (Table 3). In 4 cases, the mass extended from the right atrium into the right ventricle. Submassive pulmonary embolism was present in 2 out of 7 patients. Femoral access was used for outflow (AngioVac) cannula insertion in 6 patients and internal jugular vein in 1 patient. In 2 cases, the AngioVac cannula was advanced across the tricuspid valve for PE extraction.
Resolution of symptoms and the right atrial thrombus on echocardiography were achieved in 6 out of 7 patients (Figure 5). Extraction of the right atrial thrombus failed in 1 patient despite the multiple attempts including switching the vacuum cannula from right common femoral vein to the right internal jugular vein. This patient underwent a surgical thrombectomy and the thrombus appeared to be adherent to the atrial wall. Furthermore, small filling defects were noticed in the main pulmonary arteries on angiography after extraction of the mass in 2 out of 7 cases. Due to technical challenges, it was difficult to advance the cannula and extract the pulmonary emboli. In all 7 patients, pathological examination of the mass obtained during extraction revealed thrombus material.
One patient with submassive PE in which the thrombus extended into the lobar pulmonary artery received adjunctive thrombolytic agents through the catheter after thrombectomy. None of the patients received systemic intravenous thrombolysis. Five patients received blood transfusion during the procedure to achieve hematocrit level of 28%. Since the risk of venous thromboembolism (VTE) recurrence was thought to be high in 4 patients due to their comorbidities (ie, malignancy, recurrent VTE, and immobility due to heart failure), inferior vena cava filters were inserted. The other 3 patients did not receive inferior vena cava filter (1 patient already had a filter prior to the procedure for recurrent VTE and the other 2 patients had a catheter-associated thrombus).
The procedure was considered successful in 6 patients (Table 4). A major complication occurred in 1 patient who developed cardiogenic shock that required extracorporeal membranous oxygenation for <24 hours. There were no complications related to the procedure (ie, access hematoma, dissection, perforation of venous structures, or cardiac perforation). None of the patients had postprocedural hematocrit drop that required transfusion (4 patients with BARC type 0 and 3 patients with BARC type 1). There were no in-hospital mortalities. Average hospitalization was 20 days (range, 4-54 days). All patients received unfractionated heparin after the procedure and bridged to warfarin with international normalized ratio goal of 2-3; no patient required supplemental oxygen at discharge. Four patients were discharged to rehabilitation facility, 1 patient was discharged to hospice facility due to the poor prognosis of metastatic lung cancer, and 2 patients were discharged home.
Follow-up. Four patients were in New York Heart Association functional class I, 1 patient was in class II, and 1 patient was in class III during clinical follow-up (9 ± 4 months). One patient died from metastatic lung cancer 2 months after discharge. None of the patients were rehospitalized for recurrent venous thromboembolism during the follow-up period. All patients were on anticoagulation therapy and none of the patients were on supplemental oxygen during the follow-up period.
Discussion
Right-sided heart thrombi can develop directly within the right heart or from embolization of peripheral venous system that lodge in right heart structures in transit to the lungs. Type A thrombi with a worm-like shape are extremely mobile, frequently move back and forth through the tricuspid orifice, and may cause cardiovascular collapse when entrapment occurs. They are relatively rare and can be seen in 4%-18% of patients presenting with acute PE.6,12,13 All of our patients presented with type A thrombus. Patients with type A thrombi have a very poor prognosis, with high early mortality rates of 44% with severe and often fatal PEs.14,15 Type B thrombi, on the other hand, attach to the atrial or ventricular wall, indicating that they are probably of local origin.12 Mobile right heart thrombi causing acute PE require urgent aggressive therapy, but current management strategy remains an area of uncertainty. Thrombolytic therapy can be considered for some patients, but carries a 22% risk of major hemorrhage.5 In addition, thrombolytic therapy should be used with caution with large mobile thrombi, as the risk of fragmentation and embolization is high.16 The American Heart Association recommends surgical removal of the atrial clot if it is associated with massive PE. However, multiple medical comorbidities may prohibit the operative management; percutaneous catheter-directed therapy (PCDT) is subsequently recommended in patients with massive PE and contraindication for thrombolysis; however, no guidelines address PCDT as an option for isolated right atrial thrombus with or without submassive PE.17 Vacuum thrombectomy using the AngioVac suction cannula is an attractive modality, allowing complete en bloc removal of the right atrial thrombus and potentially avoiding a high-risk surgical procedure.
In our series, right atrial thrombus was documented in 5 cases and catheter-associated thrombus in 2 cases. They were all deemed to be high risk for surgical intervention. The use of the device resulted in successful complete evacuation of the offending mass in 6 cases. The patient outcomes were favorable despite their comorbidities, with 100% surviving to the end of their hospitalization. There were technical challenges with the use of the AngioVac catheter when used in extracting pulmonary emboli due to the size, stiffness of the catheter, and lack of steerability.18 Our series has several limitations. It is a single-center, retrospective experience, with no control group, a small sample size, and a study group including only hemodynamically stable patients.
Conclusion
In patients with mobile right heart thrombus who are not candidates for surgical intervention, this case series demonstrates the safety and feasibility of the AngioVac system for the complete en bloc removal of the thrombus. More data with larger sample size and longer follow-up are needed to clarify the appropriate patient selection for this procedure and the feasibility of vacuum-assisted thrombectomy as the first-line treatment for patients with right atrial thrombus.
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From the 1Cedars Sinai Heart Institute, Los Angeles, California; 2Lenox Hill Heart and Vascular Institute, New York, New York; and 3Hackensack University Medical Center, Hackensack, New Jersey.
Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. The authors report no conflicts of interest regarding the content herein.
Manuscript submitted October 21, 2015, provisional acceptance given November 2, 2016, final version accepted November 5, 2016.
Address for correspondence: Carlos E. Ruiz, MD, PhD, FACC, FESC, MSCAI, Professor of Cardiology in Pediatrics and Medicine, Director of the Structural and Congenital Heart Center, 30 Prospect Avenue, 5 Main, Room 5640, Hackensack, NJ 07601. Email: cruizmd@gmail.com
