Pulmonary thromboembolism treatment by percutaneous clot aspiration: case report

Abstracts

Massive pulmonary thromboembolism is an important cause of mortality. Its main cause of death is the failure of the right ventricle, due to the high resistance to its outflow, and the patient survival, on these cases, depends on prompt recanalization of the pulmonary arteries. Anticoagulation, use of thrombolytics and pulmonary embolectomy represent established therapeutic options to different clinical scenarios of pulmonary thromboembolism. Nowadays, Interventional Radiology represents an alternative to treat patients with massive pulmonary thromboembolism and contra-indications to thrombolytics, and is a less invasive option compared to embolectomy. The authors reported a case of a patient with massive pulmonary thromboembolismand contra-indication to thrombolysis, who was submitted to percutaneous clot aspiration of the pulmonary arteries, and discussed the main mechanisms of endovascular techniques of pulmonary thromboembolism treatment.

Pulmonary embolism; therapeutics; suction; thrombosis; vascular patency

O tromboembolismo pulmonar (TEP) maciço é uma importante causa de mortalidade. A principal causa de óbito é a disfunção do ventrículo direito, provocada pela alta resistência ao seu fluxo de ejeção, e a sobrevida do paciente, nessas situações, depende da pronta desobstrução das artérias pulmonares. A anticoagulação, o uso de trombolíticos e a embolectomia pulmonar representam opções terapêuticas consolidadas para diferentes cenários clínicos de TEP. A Radiologia Intervencionista representa hoje uma alternativa terapêutica para pacientes com TEP maciço e contraindicação ao uso de trombolíticos, sendo uma escolha menos invasiva do que a embolectomia. Os autores relataram um caso de paciente com TEP maciço e contraindicação à trombólise, a qual foi submetida a aspiração percutânea dos trombos das artérias pulmonares, e discutiram os principais mecanismos de técnicas endovasculares para tratamento de TEP.

Embolia pulmonar; terapêutica; sucção; trombose; desobstrução vascular

CASE REPORT

Pulmonary thromboembolism treatment by percutaneous clot aspiration – case report

Adenauer Marinho de Oliveira Góes Junior^I; Fabricio Mascarenhas^I; Guilherme de Souza Mourão^II; Henrique Elkis^II; Marco Antônio Pieruccetti^II

^IVascular surgeon; Trainee at the Service of Interventional Radiology and Endovascular Surgery of Hospital Paulistano, São Paulo (SP), Brazil

^IIInterventional radiologist; Endovascular surgeon at Hospital Paulistano, São Paulo (SP), Brazil

Correspondence

ABSTRACT

Massive pulmonary thromboembolism is an important cause of mortality. Its main cause of death is the failure of the right ventricle due to the high resistance to its outflow, and the patient survival, in these cases, depends on prompt recanalization of the pulmonary arteries. Anticoagulation, use of thrombolytics and pulmonary embolectomy represent established therapeutic options to different clinical scenarios of pulmonary thromboembolism. Nowadays, Interventional Radiology represents an alternative to treat patients with massive pulmonary thromboembolism and contra indications to thrombolytics, and is a less invasive option compared to embolectomy. The authors reported a case of a patient with massive pulmonary thromboembolismand contra-indication to thrombolysis, who was submitted to percutaneous clot aspiration of the pulmonary arteries, and discussed the main mechanisms of endovascular techniques of pulmonary thromboembolism treatment.

Keywords: Pulmonary embolism, therapeutics, suction, thrombosis, vascular patency.

Introduction

Pulmonary embolism (PE) is the blockage of pulmonary arteries or their branches by a thrombus that often originates in the deep venous system, breaks free, and, by crossing the right cavities of the heart, reaches the pulmonary circulation^1,2.

Acute PE is associated with high morbidity and mortality rates, especially during hospitalization³. Some records indicate that the hospital mortality rate for patients with massive PE is above 30%¹. The main mechanism that causes deaths is right ventricular dysfunction, and patients' survival depends on rapid recanalization of pulmonary arteries and on reduction of right ventricular ejection fraction resistance⁴. Patients with massive pulmonary embolism (PE), hemodynamic instability and right ventricular dysfunction present a poor prognosis, therefore thrombolytic therapy is indicated².

When these agents can not be used, surgical thrombectomy is an alternative technique⁵. Percutaneous procedures are additional therapeutic options for patients who present contraindication to thrombolysis, besides being an alternative to surgery^1,5.

Case report

A 51-year-old female patient with arterial hypertension underwent craniotomy with exeresis of an arachnoid cyst of the posterior fossa.

On the 13^rd postoperative day (PO), she presented with dyspnea. Upon physical examination, she was tachypneic and presented crepitant rales at bilateral pulmonary auscultation.

She was admitted to the Intensive Care Unit (ICU) and received noninvasive ventilatory support with oxygen mask; however, the pulse oximetry indicated desaturation when support was removed. The patient had arterial hypotension, but vasoactive drugs were not necessary. Chest radiography revealed diffuse pulmonary edema.

On the same day, transthoracic echocardiogram demonstrated "... heart rate at 120 bpm, moderate dilatation of the right heart chambers, moderate impairment of the right ventricular function, systolic pressure of the pulmonary artery estimated in 60 mmHg", and the conclusion was "pulmonary hypertension; moderate impairment of the right ventricular systolic function; moderate tricuspid regurgitation".

Helical CT scan of the chest with contrast (Figures 1 and 2) showed "... restrictive filling determined by intraluminal thrombi distally involving the right pulmonary artery, thus determining apparent blockage of the artery and its main branches.... restrictive filling determined by intraluminal thrombi involving the left pulmonary artery bifurcation, thus promoting apparent blockage of its main branches..."

Between the 13^rd and the 14^th postoperative days, there were no significant clinical changes. Color flow Doppler ultrasonography showed great saphenous vein thrombophlebitis and popliteal vein thrombosis, both on the left. On the 15^th PO day, the ICU medical team contacted the service of Interventional Radiology.

The patient was referred to the hemodynamics room, where pulmonary arteriography was performed by percutaneous puncture of the right common femoral vein (Seldinger's Technique), as well as a selective catheterization of the pulmonary artery trunk, right and left pulmonary arteries by a 5F pigtail catheter, which revealed patent pulmonary artery trunk with slightly increased caliber, occlusive thrombi in both pulmonary arteries, and reduction of pulmonary parenchymal perfusion (Figure 3 and 4).

Through a hydrophilic guide wire, the diagnostic catheter and the introducer sheath (5F) were removed, a 10F sheath was placed and an Aspirex^® catheter (Straub Medical) was inserted through it (Figure 5). Mechanical thrombectomy and aspiration of thrombus' fragments of the pulmonary arteries were performed.

Pulmonary arteriography revealed reduction in the number of occlusive thrombi on the pulmonary arteries, and improvement of bilateral pulmonary perfusion (Figures 6 and 7). A vena cava filter was placed on the infrarenal portion of the inferior vena cava.

Dyspnea and oxygen saturation improved and the patient was sent back to the ICU. On the day after, the follow-up echocardiogram showed "... regular sinus rhythm, heart rate of 90 bpm, moderate increase in the right chambers, moderate right ventricular systolic dysfunction, systolic pressure of 37 mmHg in pulmonary artery...", with diagnosis of "moderate pulmonary hypertension". The patient had a good recovery without intercurrences.

Discussion

The PE is an important cause of morbidity and mortality in the general population, with an estimated incidence of 0.5 per 1,000 people^1,6.

According to the extension and duration of the blockage, it may be categorized as acute, subacute and chronic. The acute form may be classified as massive or moderate when it causes, respectively, an obstruction of more or less than 50% of the pulmonary arterial bed⁷. The subacute form is characterized by multiple small and medium emboli that occur within weeks. When the obstructive process is not resolved and the embolus becomes attached to the vein wall, the embolism is categorized as chronic⁷.

Nearly 11% of the PE untreated patients have a fatal outcome in the first hour after the disease onset⁷. Until the third month, 15% of the patients die^1,6 and 4% of the acute cases develop secondary pulmonary hypertension⁸. With regard to PE with cardiogenic shock, the mortality rate reaches 70% in some studies¹. The prevention of this disease must be done, but, after its establishment, it should be promptly diagnosed and treated.

The initial therapeutic approach aims at clinical and hemodynamic stability². In massive PE, the purposes are: to promote rapid thrombolysis, to improve the performance of the right ventricle, to avoid recurrences and to decrease the risk of developing chronic pulmonary hypertension¹. The endovenous administration of unfractioned heparin is the most common approach, also demonstrably effective and indicated for all forms of PE^2,9.

The death of massive PE patients is caused by cardiogenic shock as a consequence of pulmonary arterial blockage^4,10. The survival rate depends on the rapid recanalization of the pulmonary arteries and on the reduction of resistance to the right ventricle ejection fraction⁴.

Patients with hemodynamic instability and right ventricular dysfuntion⁶, characterizing massive PTE have the worst prognosis, so thrombolytic drugs are indicated². These drugs may be administered via the endovenous approach or through a catheter placed on the pulmonary artery¹¹. Its use promotes a faster thrombolysis and reduction of the pulmonary hypertension in comparison to the isolated use of heparin. However, hemorrhagic complications are more frequent⁹. Among its absolute contraindications, we can mention recent intracranial surgery¹¹.

Pulmonary embolectomy was first used by Trendelenburg in 1908, albeit without success. Currently, this procedure is performed through median sternotomy aided by extracorporeal circulation¹¹, being indicated for massive PE with contraindications for thrombolytic therapy or for patients who do not respond to thrombolysis and remain unstable. The mortality rate disclosed by some case series varies from 10.3 to 56.4%^2,11.

Percutaneous treatments may be used when thrombolytic drugs are prescribed⁵, being considered alternatives for surgical treatment^1,3 especially in cases of high surgical risk^9,10. Percutaneous catheter interventions aim to reduce pulmonary vascular resistance, thus reducing resistance to the right ventricular ejection fraction and improving the cardiac debt⁵.

Some techniques do not require specific devices and use diagnostic catheters such as the conventional "pigtail", or little modified, aiming at mechanical fragmentation of the thrombus, which may or may not be associated with local infusion of thrombolytic drugs^1,4,5,10,11.

The first percutaneous system created over 30 years ago specifically for the treatment of massive pulmonary embolism is the Greenfield Embolectomy Device (Boston Scientific^®). Since then, many options have become available, such as: Hydrolyser Catheter (Cordis^®), Angiojet Rheolytic Thrombectomy System (Possis^®), Oasis Catheter (Boston Scientific^®), Amplatz Thrombectomy Device (Microvena^®), Impeller Basket Device and Rotable Pigtail Catheter (Cook^®), Kensey device (Dow Corning), Straub Rotarex System^® and Aspirex^® (Straub Medical), which was employed in this case, among others^3,9,11.

Endovascular therapy function through many techniques or combinations of techniques, e.g., aspiration of the thrombus through sheaths or guiding catheters, fragmentation of the thrombus by means of catheters, angioplasty balloons, guide wires, maceration by high-speed rotational catheters, fragmentation and aspiration through hydrodynamic catheters, and pulmonary artery stenting^5,9,11. Whatever method is used, the endovascular techniques aim at unblocking the pulmonary artery trunks by aspiration or fragmentation and dispersion of the thrombi to peripheral arteries^2,9,10,11. The fragmentation of a central thrombus and the displacement of its fragments to the peripheral portion result in increased area of unblocked transverse section in the pulmonary arterial tree, because arteries measuring 1 mm in diameter have twice the area of the transverse section in comparison to those of the trunk arteries^1,4,11. In patients with severe right ventricular dysfunction, it may result in hemodynamic improvement. Besides that, the increase of total thrombus surface promoted by the percutaneous fragmentation accelerates the pharmacological or spontaneous lysis^1,4,10,11.

The Aspirex device (Straub Medical^®) is a rotational catheter that exerts a negative pressure through an aspiration system in "L", macerating the thrombus and removing it by aspiration. The device is connected to an engine that generates a 40,000 rpm frequency. The catheter is, then, introduced on a 0.018 guide wire and advanced to the proximal portion of the pulmonary artery occlusion or wherever a major number of thrombi is found; then, it is operated³.

The indications currently accepted as to the use of percutaneous techniques include arterial hypotension (systolic <90 mmHg or a drop <40 mmHg), cardiogenic shock, cardiopulmonary resuscitation, right ventricular dysfunction, precapillary pulmonary hypertension, alveolar-arterial oxygen gradient >50 mmHg and clinically significant pulmonary embolism with contraindication for thrombolytic therapy³.

The angiographic results of the interventional procedures are not important: the procedure must be concluded after obtaining improvement of hemodynamic parameters regardless of the presence of residual thrombi revealed by the control arteriography⁵.

Two published meta-analyses point out success rates of 71% with the use of various percutaneous techniques for treating PE, increasing to 90% when associated with catheter-guided thrombolysis³.

Among the reported complications, one can mention right ventricle perforation, tricuspid failure, significant bleeding in the vascular access and mechanical hemolysis. The mortality rate varies from 0 to 25%³.

Final comments

The bibliographical references state that the percutaneous interventions represent the only alternative therapy to the detriment of surgical embolectomy in massive PE patients with contraindications to thrombolytic therapy.

There are data in literature that assure the efficacy and safety of these devices. However, this promising therapeutic modality requires further studies to have its place established in the algorithms for PE treatment. Because of the significant potential for complications, its use should be restricted to patients with massive PE.

References

• 1. Barbosa MAO, Oliveira DC, Barbosa AT, et al. Tratamento do tromboembolismo pulmonar maciço por fragmentação percutânea do trombo. Arq Bras Cardiol. 2007;88:279-84.
• 2. Sociedade Brasileira de Cardiologia. Diretriz de embolia pulmonar. Arq Bras Cardiol. 2004;83:2-8.
• 3. Eid-Lidt G, Gaspar J, Sandoval J, et al. Combined clot fragmentation and aspiration in patients with acute pulmonary embolism. Chest. 2008;134:54-60.
• 4. Schmitz-Rode T, Janssens U, Duda SH, Erley CM, Günther RW. Massive pulmonary embolism: percutaneous emergency treatment by pigtail rotation catheter. Journal of the American College of Cardiology. 2000;36:375-80.
• 5. Kucher N, Goldhaber SZ. Mechanical catheter intervention in massive pulmonary embolism: proof of concept. Chest. 2008;134:2-4.
• 6. Wan S, Quinlan DJ, Agnelli G, Eikelboom JW. Thrombolysis compared with heparin for the initial treatment of pulmonary embolism: a meta-analysis of the randomized controlled trials. Circulation. 2004;110:744-9.
• 7. Jatene FB, Bernardo WM. Isquemia pulmonar embólica: aspectos clínicos e experimentais. Rev Assoc Med Bras. 2003;49:342-8.
• 8. Sociedade Brasileira de Pneumologia. Hipertensão pulmonar tromboembólica. J Bras Pneumol. 2005;31:S28-S31.
• 9. Uflacker R. Terapêutica no tromboembolismo pulmonar. In: Carnevale FC. Radiologia intervencionista e cirurgia endovascular. 1Ş ed. Rio de Janeiro: Revinter; 2006. p. 409-34.
• 10. Tajima H, Murata S, Kumazaki T, Nakazawa K, Abe Y, Komada Y, et al. Hybrid treatment of acute massive pulmonary thromboembolism: mechanical fragmentation with a modified rotating pigtail catheter, local fibrinolytic therapy, and clot aspiration followed by systemic fibrinolytic therapy. AJR. 2004;183:589-95.
• 11. Murad H, Murada FF. Embolia pulmonar: tratamento cirúrgico. In: Brito CJ. Cirurgia vascular: cirurgia endovascular angiologia. 2Ş ed. Rio de Janeiro: Revinter; 2008. p. 1716-26.

Publication Dates

• Publication in this collection
  09 Feb 2011
• Date of issue
  Sept 2010

History

• Received
  17 Nov 2009
• Accepted
  26 May 2010