Thrombolysis versus Thrombectomy in Acute Deep Vein Thrombosis

Gerard J O'Sullivan

Interv Cardiol. 2011;3(5):589-596.

Abstract and Introduction

Abstract

Deep vein thrombosis (DVT) is a significant health problem, leading to the hospital admission of over 250,000 Americans each year. Its most serious acute complication, namely pulmonary embolus, kills approximately 100,000 each year, and is the third most common cardiovascular related mortality after myocardial infarction and stroke. Chronic leg problems following DVT include leg heaviness, tiredness, cramping and ulceration. These are termed the post-thrombotic syndrome. The current standard therapy of anticoagulation has changed little over 50 years. It does not remove or destroy thrombus, relying instead on the bodies own fibrinolytic mechanisms to do so. DVT needs to be more accurately categorized on an anatomical basis, and for a variety of reasons, the area of most importance is the iliofemoral region. The rationale for active, rather than passive, thrombus removal relies on multiple observations that, by doing so improves luminal patency, restores valvular function and has the potential to reduce the severity of post-thrombotic syndrome. Techniques for thrombus removal include catheter-directed thrombolysis, mechanical thrombectomy and various combinations of both (pharmacomechanical catheter-directed thrombolysis). There are no direct trials comparing these different forms of treatment. Each has shown reasonable efficacy as detailed in the literature below.

Introduction

Acute deep vein thrombosis (DVT) is a major health issue causing approximately 300,000–600,000 new cases per annum in the USA.^[101] Venous thromboembolism accounts for more deaths than the total combined mortality of breast cancer, road traffic accidents and AIDS combined.^[101] It is the third most common cause of cardiovascular mortality after myocardial infarction and cerebral vascular accidents. Apart from the initial symptoms, which may be severe and progress to phlegmasia cerulea dolens, there is the risk of pulmonary embolic disease that can be life threatening. The chronic subsequent leg problems of leg swelling, pain, ulceration and so on are termed the 'post-thrombotic syndrome' (PTS).

Conventional management of acute DVT is based upon one trial from 1960 and several subsequent observational trials.^[1–3] It has changed little over that time. This consists of immediate anticoagulation (AC) with heparin or, more recently, low-molecular-weight heparin (LMWH) followed by 3 months of oral AC. However, neither of these treatments offers significant fibrinolytic activity, relying instead on the body's own urokinase.

Acute DVT refers to symptoms less than 14 days.

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Next Section

Table 1. Medical–surgical interventions to treat deep vein thrombosis.
Approaches	Indications for DVT	Technical purpose	Considerations	Ref.
Systemic anticoagulation	Accepted conservative gold standard for all DVT	Prevents further propagation of thrombus or PE	Does not physically attack thrombus; bleeding rate 2–4%. When treated with anticoagulant alone, patients with iliofemoral DVT continue to have high incidence of chronic painful edema (75%) and venous claudication (40%)	[4]
Systemic thrombolysis	No indication for isolated DVT Useful in PE	Accelerates thrombus lysis indiscriminately throughout body	Major bleeding rate is risky and extremely variable. High dependency monitoring needed over hours or days	[8]
Surgical thrombectomy - open venous - balloon	Cases refractory to less invasive interventions	Removes thrombus	Invasive; requires general anesthesia; may delay stenting; slower mobilization and longer recovery post-surgery; experience limited to a few centers	[11]
CDT - simple - ultrasound-assisted (EKOS Endowave®)	Serious DVT and/or PE	Directs iv. thrombolytic agent physically within thrombosed area	ICU monitoring 24–72 (average 48 h); lytic agent migrates systemically; potential hemorrhage; major bleeding rate 5–11% US-aided: CDT time is reduced to median 22 h and bleeding rate to 3.8%	[24,36]
Percutaneous mechanical thrombectomy (Trerotola and Angiojet®)	When thrombolytics are absolutely contraindicated	Removes thrombus with action of rotary, scraping, or high-powered water jets	Potential vein wall damage and hemolysis	[26]
Pharmacomechanical thrombolysis (Angiojet®)	Single-session treatment of DVT	High-powered water jets increase action of iv. thrombolytic agent directed to the site of the thrombus	Potential hemolysis; proximal to heart has been occasionally associated with microemboli and bradycardia systemic release of lytic agent	[22]
Isolated pharmacomechanical thrombolysis (Trellis)	Single-session treatment of DVT	Macerating wire increases action of iv. thrombolytic agent directed to the site of the thrombus	Isolates lytic agent, restricting systemic release requires an 8F sheath, so cannot really be used below mid calf; has a small-caliber aspiration lumen	[44,46]

Box 1. Accelerated thrombus removal mechanisms.
*Rotational Mechanical* A fragmentation cage pulled through the vein macerates and strips thrombus from the vein walls (Trerotola Arrow; PA, USA)[26] *Isolated pharmacomechanical thrombolysis* Balloons largely confine the treatment area, where a thrombolytic agent is dispersed through thrombus with a rotating wire (Trellis, Covidien; CA, USA) [44,46] *Bernoulli's principle effect* High-powered jets fragment the thrombus into microscopic pieces (Angiojet ® , Medrad Interventional/Possis; PA, USA) [22] *US-assisted catheter-directed thrombolysis* US waves partially fragment thrombus that can be attacked by a thrombolytic agent (EndoWave™/EkoSonic ® , Ekos ® , WA, USA) [36]

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