|Year : 2018 | Volume
| Issue : 2 | Page : 81-87
Catheter-based management of pulmonary embolism
Bishav Mohan1, Shibba Takkar Chhabra1, Amit Verma1, Hasrat Sidhu2, Abhishek Goyal1, Bhupinder Singh1, Naved Aslam1, Gurpreet Singh Wander1
1 Department of Cardiology, Dayanand Medical College and Hospital, Unit Hero DMC Heart Institute, Ludhiana, Punjab, India
2 Department of Medicine, Dayanand Medical College and Hospital, Ludhiana, Punjab, India
|Date of Web Publication||10-Sep-2018|
Dr. Bishav Mohan
Department of Cardiology, Dayanand Medical College and Hospital, Unit Hero DMC Heart Institute, Ludhiana, Punjab
Source of Support: None, Conflict of Interest: None
Background: Pulmonary embolism (PE) is a major cause of mortality and morbidity. Forty-four percent of patients would not have gotten intravenous (IV) thrombolysis due to contraindications or delay. Catheter-directed thrombolysis with fragmentation has been shown to improve short-term and long-term outcomes in acute high-risk patients of pulmonary embolism. Methodology: Patients presented de nova with massive pulmonary embolism or with subacute pulmonary embolism. Some presented with failed thrombolysis from other centers. Results: Our experience from these patients shows that a policy of mechanical thrombus breakdown with a 5F multipurpose or pigtail catheter followed by a urokinase infusion can achieve satisfactory results. Fifty patients with acute were treated with thrombolysis with or without mechanical breakdown. There was 96% event-free survival. With subacute PE, using a mechanical breakdown plus IV thrombolysis, there was fall in pulmonary arterial pressures (PAPs) with 100% 6-month event-free survival. In seven patients with failed thrombolysis, this strategy leads to fall in PAPs and 100% survival at 2 years. Conclusions: Various catheter-based techniques are available which can be used in combination with thrombolysis to achieve good results. Surgery should be considered if the catheter-based techniques fail.
Keywords: Catheter-based management, mechanical breakdown, pulmonary thromboembolism
|How to cite this article:|
Mohan B, Chhabra ST, Verma A, Sidhu H, Goyal A, Singh B, Aslam N, Wander GS. Catheter-based management of pulmonary embolism. J Pract Cardiovasc Sci 2018;4:81-7
|How to cite this URL:|
Mohan B, Chhabra ST, Verma A, Sidhu H, Goyal A, Singh B, Aslam N, Wander GS. Catheter-based management of pulmonary embolism. J Pract Cardiovasc Sci [serial online] 2018 [cited 2019 Feb 19];4:81-7. Available from: http://www.j-pcs.org/text.asp?2018/4/2/81/240964
| Introduction|| |
Pulmonary thromboembolism (PE) is a major cause of mortality, morbidity, and hospitalization. 3.17 lakh deaths were reported in six countries of the European Union in 2004. Fifty-nine percent of deaths were resulting from that remain undiagnosed during life. Only 7% of patients were correctly diagnosed before death. Thirty-day all-cause mortality is 9%–11% and 3 months is 8.6%–17%. Thirty-four percent of cases present as sudden cardiac death. In this article, we review the world literature and also present our data.
PE is not uncommon but has a clinically variable presentation ranging from asymptomatic to massive PE. Massive PEs are characterized by >50% pulmonary arterial (PA) compromise, leading to right ventricular (RV) failure, circulatory collapse, hypotension, and/or shock. Mortality rate without treatment of massive PE is approximately 30%, usually within the first few hours of the initial event.
The goal of therapy in patients presenting with massive PE is rapid recanalization of PAs with thrombolysis or embolectomy, to decrease RV afterload and reverse RV failure and shock, decrease the risk of recurrence, and prevent chronic thromboembolic pulmonary hypertension. Intravenous (IV) thrombolytic therapy is the first-line treatment in patients with high-risk PE presenting with cardiogenic shock and/or persistent arterial hypotension. A substantial proportion of patients, however, may not be eligible for IV thrombolysis because of major contraindications. Surgical embolectomy is an alternative therapeutic option in patients in whom thrombolysis is absolutely contraindicated or has failed. However, a number of experienced tertiary care centers with around-the-clock availability of emergency surgical embolectomy are limited. Percutaneous catheter embolectomy or mechanical fragmentation of proximal PA clots followed by local thrombolytic therapy may be considered as a very attractive alternative to surgical embolectomy and systemic thrombolysis because of their capacity to establish pulmonary blood flow rapidly. Reports have shown that mechanical fragmentation combined with local thrombolysis is a good therapeutic option for restoring pulmonary flow and decreasing PA pressure, with comparable short-term outcomes to systemic thrombolysis.
The general principle of relieving obstruction rapidly and restoring pulmonary blood flow is logical, with the aim of improving cardiac output and returning the patient to a hemodynamically stable state. While achieving several goals including improved RV function, reduced length of stay, reduced risk of chronic thromboembolic pulmonary hypertension, improved quality of life, and improved mortality with catheter-based approaches would be ideal, at present, randomized trial data are inadequate to demonstrate these.
Evidence-based consensus statements have offered recommendations for the use of novel catheter-based approaches for reducing clot burden but have been limited by the limited number of controlled trials.,,
It is important to clarify terminology. The term “catheter-based therapy” (CBT) refers to the use of any of several devices and techniques in the PA with or without low-dose thrombolytic therapy.
The term “catheter-directed thrombolysis” (CDT) refers to the infusion of thrombolytics into PA through an infusion catheter with multiple exit ports, placed into PA, preferably into the embolus.
Pharmacomechanical thrombolysis refers to low-dose thrombolysis combined with additional mechanical measures (i.e., more than simply direct intraembolic infusion) such as fragmentation to aid in eliminating the emboli.
A recent analysis of the National Inpatient Sample database indicates that utilization of CBT has increased since 2010. It was shown based on a propensity-matched analysis of a cohort of 352 in patients with PE who underwent CBT compared to 352 in patients who had systemic thrombolysis that the in-hospital mortality rate was approximately 10% which was significantly lower than the rates for systemic thrombolysis (20%). There were very low rates of intracranial hemorrhage (ICH) (0.28%) and no ICH after 2010. This was, however, at the expense of higher rates of acute renal failure requiring hemodialysis and higher cost. The gradually decreasing major bleeding rates may reflect increasing experience and use of lower doses of thrombolytic agents with newer catheter-based devices.
The data available and clinical experience with certain techniques strongly suggest that there can be beneficial and that these approaches should continue to be pursued.
Why consider a catheter-based approach to acute pulmonary embolism?
The proportion of unstable PE patients receiving systemic thrombolytic therapy in the United States appeared to decrease from 40% in 1999 to 23% in 2008. The reasons for this decrease may relate to the continued concern regarding devastating bleeding complications, particularly ICH, as well as the results of recent studies, suggesting relative safety and efficacy of CBT. Unfortunately, as effective as systemic thrombolysis can be, the incidence of major bleeding and ICH is clearly higher than with anticoagulation alone. This persisting obstacle together with advances in surgical techniques and catheter technology has prompted alternate treatment options, including lower dose systemic fibrinolysis, surgical embolectomy, and a number of catheter-based approaches. In spite of several promising studies suggesting the improved safety and acceptable efficacy of lower doses of systemic thrombolytic agents, for example, 50 mg of IV tissue-type plasminogen activator (tPA), an acceptable reduction in the risk of major bleeding and ICH has not been satisfactorily proven.
The pulmonary embolism thrombolysis trial was a major effort to better characterize the efficacy and safety of IV thrombolysis in intermediate-risk PE. Unfortunately, while the primary endpoint was met, the overall mortality was exceedingly low in both treatment arms and the ICH rate, while low was clearly higher than when only anticoagulation was given. These results suggested that if therapy beyond anticoagulation was to be pursued further, it should be done in a lower risk manner. Catheter-directed therapy, with or without low-dose thrombolysis, is one potential answer.
Potential indications for catheter-based therapy
High-risk PE with mild hypotension or intermediate-risk PE with more severe degrees of RV dysfunction and positive biomarkers and/or more severe hypoxemia are feasible scenarios for CBT. Given the low risk for major complications, it is reasonable to consider CBT, in patients with massive PE who have been reasonably stabilized and with contraindications to systemic thrombolysis and in patients on the more severe end of the intermediate-risk spectrum (patients with severe RV dysfunction by echocardiography and positive biomarkers). Other special subgroups include failed thrombolysis, thrombolysis with PE after 7–10 days, severely compromised patients, age >65 years. The potential advantages of a catheter-based procedure include the use of either no thrombolytic agent or low-dose thrombolysis, thus offering the possibility of more rapidly reducing the clot burden with what appears to be a reduced risk of major bleeding including ICH.,
Which catheter-based therapeutic options have been utilized?
Several percutaneous catheter-based techniques have been utilized for the treatment of high-risk and intermediate-risk PE as shown in [Table 1] and [Figure 1].
|Figure 1: (a-i) Various devices that have been utilized to treat acute pulmonary embolism are shown.|
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Catheter-directed, low-dose thrombolysis
Although anticoagulation with heparin alone has little effect on improvement of RV size and performance within the first 24–48 h, the extent of early RV recovery after low-dose CDT appears comparable to that of after standard-dose systemic thrombolysis. Bleeding complications appear to occur less frequently with CDT than with full-dose systemic thrombolysis, and thus, this procedure has been commonly performed in patients with intermediate- and high-risk PE with relative contraindications to systemic thrombolysis. The thrombolytic agent is infused into PA, with or without ultrasound assistance in an attempt to deliver it within the embolism. Thrombolytic agents are usually administered as a continuous infusion, and a bolus may be considered at the time of catheter placement in patients who are hemodynamically unstable or appear to be worsening. Many of these studies have suggested improvement but without comparison of anticoagulation arms. There is no standard thrombolytic agent, infusion duration, or drug dose utilized in CDT although tPA has been most commonly utilized, and approximately 20 mg of tPA has been delivered over approximately 12–24 h in larger studies.,,
We looked at our experience with CDT and presented the data here.
| Methodology|| |
Patients presenting to our hospital with acute/subacute pulmonary embolism were taken up for thrombolysis or CDT with fragmentation.
Anticoagulation is initiated in all PE patients unless it is contraindicated. When CBT is considered, IV heparin is often utilized since it has a short half-life and is reversible. Rapid access to the cardiac catheterization or interventional radiology laboratory is crucial, if more critically ill PE cases are to be considered. Preparation and PA access are similar but not identical for the various CBT options.
After giving local anesthesia, 6F sheath is introduced in the femoral vein for procedure. The 6F standard pigtail catheter is used to obtain initial pulmonary angiography for confirmation of massive pulmonary embolism [Figure 2]. Mechanical recanalization of thrombus is done with a multipurpose catheter followed by fragmentation and thrombus suction with 6F pigtail. After ensuring flow across affected PA, urokinase (UK) in dose of 4400 IU/kg body weight is given intralesionally over 10 min and followed by 2200 IU/kg/h for 12 h through a pigtail catheter kept in PA with maximum thrombus burden.
|Figure 2: Pulmonary angiography. (a) Total cutoff of right pulmonary artery; (b) mechanical breakdown and intrapulmonary urokinase administration; (c) postprocedural pulmonary angiography revealing restoration of pulmonary flow in right pulmonary artery and its branches.|
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| Results|| |
Fifty patients came for primary care with pulmonary embolism [Table 2]. Their mean age was 47 ± 12 years. They were treated with mechanical thrombus breakdown with a 5F pigtail followed by a UK infusion. The hemodynamics are shown in [Table 2], and the pulmonary pressure reduced with a rise in systemic pressure. Two patients had early death, two needed an inferior vena cava (IVC) filter, one had late death, and one had a late pulmonary embolism.
|Table 2: Acute pulmonary embolism: Patients coming for primary care (n=50)|
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In patients with subacute pulmonary embolism [Table 3], n = 8], a multipurpose catheter was used for thrombus breakdown and suction followed by thrombolysis.
|Table 3: Subacute pulmonary embolism: Patients presenting after 2 weeks (n=8)|
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In patients with failed thrombolysis [Table 4], n = 7], the protocol was similar with the use of a multipurpose catheter followed by a UK infusion.
|Table 4: Acute pulmonary embolism: Patients with failed thrombolysis in shock (n=7)|
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| Discussion|| |
CDT with fragmentation has been shown to improve the short-term and long-term outcomes in acute high-risk patients of pulmonary embolism as shown from the study from our center. In our patient population, 44% of patients would not have been able to receive IV thrombolysis due to contraindications [Table 2].
Patients with massive pulmonary embolism presenting subacutely (>2 weeks) have high mortality, and older clots in these patients may be less amenable to thrombolysis with increased likelihood of recurrence and thromboembolic pulmonary hypertension, and if not responding, they are candidates for surgical thromboembolectomy [Table 3]. Postprocedurally, patients documented significant improvement in hemodynamic parameters with 100% survival at 30-day and 6-month follow-up. This modality appears to be a promising alternative to high-risk surgical procedures in such patients.
The subgroup of patients of massive pulmonary embolism who were treated with IV thrombolysis but failed to respond to the treatment poses a therapeutic challenge in view of high-risk bleeding and mortality during surgery. Mechanical thrombosuction and intraembolus lysis in such patients have been shown to be a promising alternative strategy [Table 4].
In acute pulmonary embolism, recanalization should be done using a pigtail followed by thrombosuction and lysis using thrombolytic agent [Figure 3].
For older organized clot, increased clot surface by mechanical fragmentation followed by thrombolysis causes increased velocity of thrombolysis as shown in [Figure 4].
|Figure 4: Schematic drawing demonstrating the effect of mechanical fragmentation of a total occlusive central thrombus in the pulmonary artery, before (a) and after (b) mechanical fragmentation and dispersion of the smaller clots into the peripheral branches of the pulmonary artery. Fragmentation and distal dispersion are likely to reduce pulmonary arterial pressure and increase total pulmonary perfusion.|
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The thrombolytic agent, UK, specifically catalyzes the cleavage of the Arg-Val bond in plasminogen to form plasmin which breaks down the fibrin polymers of blood clots. Among the plasminogen activators, UK provides a superior alternative for the simple reasons of it is more potent as compared to t-PA and nonantigenic by virtue of its human origin, unlike streptokinase. UK has direct catalytic activity against fibrinogen and renders it less clottable by thrombin by releasing fibrinopeptide B, a potent chemoattractant. Henceforth, they concluded that UK may participate in processes extending beyond fibrinolysis, a property which might especially be relevant in our patients with subacute PE and relatively older thrombus in process of organization. Moreover, in a randomized controlled multicenter trial of recombinant tissue plasminogen activator (rt-PA) versus UK in the treatment of acute pulmonary embolism, it was found that despite rapid clot lysis at 2 h by rt-PA, at 24 h, both drug regimens had produced equally good reperfusion. Furthermore, in terms of cost and availability in developing nations, UK might be a preferred option.,
Ultrasound-facilitated, catheter-directed therapy
The low-dose CDT technique with the most controlled supportive clinical trial data involves a local, slow infusion of a thrombolytic agent through low-profile catheters placed in the obstructed PA using the high-frequency low-power EkoSonic ultrasound technique, that is, ultrasound-facilitated CDT; ultrasound exposure causes a reversible disaggregation of uncross-linked fibrin fibers, which may create additional binding sites and facilitate the thrombolytic effect. Furthermore, ultrasound pressure waves may increase thrombus penetration of thrombolytic drugs by “acoustic streaming.”
The 5.2F infusion catheter contains three lumens with one for the inner ultrasound cable, one for the drug infusion, and one for the coolant (normal saline). Most commonly, an ultrasound/infusion catheter is placed in each lung. A commonly used tPA dose is 0.5–1.0 mg/h per catheter. The total tPA dose is typically between 12 and 24 mg, delivered over 12–24 h. A low-dose, weight-based heparin infusion is continued during the thrombolytic infusion, with a target partial thromboplastin in the low therapeutic range (e.g., 40–60 s). The coolant is infused at approximately 35 mL/h. The ULTIMA trial showed that in PE patients at intermediate risk, a standardized ultrasound-assisted CDT regimen was superior to anticoagulation with heparin alone in reversing RV dilatation at 24 h, without an increase in bleeding complications. Similarly, the SEATTLE II trial showed that ultrasound-facilitated, catheter-directed, low-dose fibrinolysis decreased RV dilation, reduced pulmonary hypertension, decreased anatomic thrombus burden, and minimized ICH in patients with acute massive and submassive PE. This is the only catheter-based therapy technique studied in a randomized controlled trial and the Food and Drug Administration approved specifi cally for the treatment of acute pulmonary embolism.
Several aspiration techniques have been employed and can be attempted using regular 8F or larger guide catheters or more specialized catheters. The earliest experience was obtained with a 10F Greenfield suction embolectomy catheter. The device allowed extraction of the centrally located emboli using sustained suction with a large syringe. The device proved effective but was somewhat cumbersome based on the requirement for a surgical cutdown for access and the need to retrieve the device and the emboli as a unit. Manual suction embolectomy has been utilized alone or as an adjunct to other techniques. The guide catheter is advanced into the embolism in the right or left PA. Suction is applied with a 20–50 mL syringe, while the catheter is moved slowly back and forth over several centimeters within the clot.
The AngioVac cannula is a 22F venous catheter that removes emboli utilizing a centrifugal pump and venous reinfusion cannula with the latter minimizing blood loss. The device is Food and Drug Administration (FDA) approved for the “removal of undesirable intravascular material” including fresh, soft thrombi, or emboli. The AngioVac catheter consists of a balloon-expandable, funnel-shaped distal tip, which improves removal of large emboli from the right heart chambers or proximal PAs.
Simple catheter fragmentation procedures fragmentation of emboli is a relatively simple and rapid technique and does not require complex resources. The theory is that by mechanically disrupting occlusive proximal emboli into smaller fragments, improved peripheral flow can be achieved. This has been successfully achieved by manually rotatiing a pigtail catheter or by employing a balloon angioplasty catheter.
Repeated injections of saline into large proximal emboli have been performed analogously to catheter fragmentation. A more formal approach has employed a high-pressure saline jet generating a pressure gradient through Bernoulli's principle, enabling the dissolution and removal of emboli.
This device the AngioJet also permits the local injection of thrombolytic agents by the “power-pulse” spray technique, forcing the drug into the emboli. Massive hemoptysis, renal failure, and death from bradycardia and apnea have been reported. This resulted in a black box warning from the FDA for the use of AngioJet in acute PE.,
Catheter-directed extraction embolectomy
The FlowTriever device is a catheter-based mechanical device for percutaneous endovascular retrieval of emboli and is intended for the use in the proximal (lobar and main) PA system. The device is composed of the FlowTriever catheter with an integral self-expanding wireform consisting of three nitinol disks, an aspiration guide catheter, and a retraction aspirator. Clinical improvement may result from both clot extraction and improved perfusion through penetrating the emboli. The device is intended for the use without thrombolytic agents, but thrombolytics (and contrast dye) can be infused through the aspiration guide catheter. Successful use of the FlowTriever device in a critically ill massive PE patient who failed systemic thrombolysis has been reported.
Catheter-based therapy: Complications
There are several potential complications of CBT techniques for acute PE. Some involve access to the right heart and PAs, and manipulation of catheters once access is accomplished. These include major access site bleeding, significant arrhythmias, PA dissection or perforation, pericardial tamponade, worsening hypoxemia and hemodynamics, recurrent PE, and distal clot embolization. Others may relate to the specific procedure, such as hemolysis/hemoglobinuria, as described earlier with rheolytic therapy.
Maintenance of anticoagulation postintervention is critical to prevent recurrent clot formation. However, patients who have had a recent catheter-based intervention are at the risk of access site bleeding. One strategy to potentially reduce bleeding risk is to hold the heparin drip for 1–2 h after sheath removal and then restart without a bolus. Oral anticoagulation or low-molecular-weight heparin (LMWH) can be initiated once clinical evaluation. However, no guidelines indicate when or how anticoagulants should be initiated post-CBT, especially if thrombolytic agents have been administered. We suggest heparin alone for the first 24–48 h postintervention with initiation of a DOAC or warfarin subsequently (or LMWH in active cancer patients). Both the American and the European guidelines do not recommend routine use of IVC filters in patients with PE.,,
What do consensus statements say?
The American Heart Association, the European Society of Cardiology, and the American College of Chest Physicians, all offer recommendations for the use of catheter-based approaches to acute PE [Table 5].
|Table 5: Recommendations for the use of catheter-based approaches to acute pulmonary embolism|
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| Conclusions|| |
CBT of acute PE is an evolving subject. All procedures are not the same, and the preferences are often based on local resources and expertise. We would recommend continued efforts at rapid diagnosis and referral to an experienced team for risk stratification. Direct embolus dissolution and/or clot removal without thrombolysis may be better options for patients who either cannot receive thrombolysis or cannot wait for a slower thrombolytic infusion to take effect. Although some centers have reported favorable outcomes with surgical embolectomy as the first-line management of intermediate- and high-risk PE, we believe that with our personal experience, this should be reserved for patients with massive PE and shock, who have contraindications to thrombolysis, who have failed other treatments, or who have concomitant intracardiac thrombus or paradoxical embolus.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]