Cath Lab Digest

Background
Multiple sequellae may occur after deep venous thrombosis (DVT), including acute limb symptoms such as swelling and pain, valvular damage and reflux leading to chronic symptoms, and, the most serious, pulmonary embolism and death. Venous thromboembolic disease, including both DVT and pulmonary embolism, is an under-diagnosed medical problem that results in high rates of significant patient morbidity and mortality. Conventional therapy consists of anticoagulation with heparin and warfarin in the setting of an acute DVT, which prophylaxes against clot propagation and pulmonary embolism, but does not relieve thrombus burden. The delayed complications of DVT, known as the post-phlebitic syndrome, are due to valvular damage from chronic thrombus and scarring.

Techniques aimed at venous valve preservation and restoration of venous patency should theoretically decrease venous hypertension, reducing the incidence and degree of post-thrombotic symptoms. The ability of interventions such as anticoagulation therapy, thrombolytic therapy, and surgical/ endovascular thrombectomy to restore venous patency, remove obstruction, and ultimately decrease the incidence and severity of reflux in a diseased extremity can be used to return patients to their normal way of life. Unfortunately, no therapeutic options or interventions to date have demonstrated superiority over anticoagulation. Consequently, anticoagulation remains the “gold standard” of care while new modalities are being evaluated.

Endovascular management utilizing percutaneous mechanical thrombectomy (PMT) alone or in combination with pharmacological thrombolytic agents is safe and effective in reducing thrombus burden. Along with possible preservation of venous valve function, inciting anatomic lesions may be treated simultaneously. However, the experience is limited. We advocate adjunctive measures, such as the addition of lytic agent to the PMT therapy, to increase the speed and efficacy of thrombus removal. We will present herein a novel technique of percutaneous mechanical thrombectomy with concomitant lytic therapy for the treatment of venous thrombotic disease with an example of successful use.

Case Presentation
A 53-year-old male presented to the emergency room with a two-day history of right lower leg swelling. He had just completed an eight-hour transatlantic flight four days prior to presentation. He described significant right calf and thigh swelling and pain. There was no significant past medical history and no recent trauma to his lower extremity. Physical examination revealed marked swelling of right lower extremity, involving the calf and the thigh, that was tender to touch. Venous duplex ultrasound revealed a large, echolucent density in the right common femoral vein, which was non-compressible, consistent with acute deep venous thrombosis (DVT). The thrombus extended proximally to the external and common iliac veins as well as distally to the superficial femoral and popliteal veins.

Percutaneous Mechanical Thrombectomy (PMT)
Relief of clot burden by directly extracting thrombus surgically or via lytic dissolution should hypothetically decrease the risk of pulmonary embolism and also that of post-thrombotic syndrome, which may lead to manifestations of chronic venous insufficiency. Primarily because of the bleeding risks of catheter-directed thrombolysis, PMT has emerged as an advantageous option for the treatment of acute DVT (<14 days). One of the PMT systems which have been shown to be effective in the removal of acute DVT is the AngioJet® (Possis Medical Inc, Minneapolis, MN) percutaneous mechanical thrombectomy system. The principle of this device is based on the Bernoulli principle, which creates high velocity saline jets that are directed backward from the tip of the device to outflow channels in a coaxial fashion. This generates a vacuum force that draws the thrombus into the catheter. One major advantage of this percutaneous treatment modality is that the thrombectomy catheter can be delivered through a small-bore introducer sheath (6 Fr), effectively reducing access site trauma and avoiding operative exposure required with the conventional Fogarty thromboembolectomy. A clinical study which evaluated the efficacy of the AngioJet system has demonstrated that such a mechanical thrombectomy system is effective in thrombus removal, venous patency restoration, and maintenance, and symptom relief.1 The Angiojet® rheolytic thrombectomy system is designed to produce an area of extremely low pressure at the catheter tip by controlled high velocity saline jets. Via this mechanism, thrombus surrounding the catheter tip is macerated and rapidly evacuated via an effluent lumen into a collection chamber.

Several authors have evaluated multiple PMT catheters in the treatment of DVT. However, to date, there is no prospective, randomized trial data available. In one review, Vedantham et al. used percutaneous mechanical thrombectomy with catheter-directed thrombolysis (CDT) for the treatment of lower extremity DVT (several devices tested included the Amplatz Thrombectomy Device, Microvena, White Bear Lake, MN; AngioJet, Possis Medical Inc, Minneapolis, MN; Trerotola Percutaneous Thrombectomy Device, Arrow International, Reading, PA; Oasis, Boston Scientific/Meditech, Natick, MA).2 Procedural success was achieved in 82%, with underlying culprit stenoses uncovered and stented in 15 patients (18 limbs). These authors reported substantial thrombus removal with the two techniques combined compared to either alone. Another group (Delomez), using only the Amplatz Thrombectomy Device, reported successful recanalization of the thrombosed segment in 83% of patients with proximal DVT.3 At 29.6 months follow-up, 10 patients had minimal symptoms relating to the episode and only one patient had developed post-thrombotic sequellae.