Chest
Antithrombotic Therapy for Venous Thromboembolic Disease
Section snippets
Effective Regimens
Treatment regimens for DVT and PE are similar because the twoconditions are manifestations of the same disease process. Whenpatients with VTE are carefully studied, the majority of those withproximal DVT also have PE (symptomatic or asymptomatic) and viceversa. Furthermore, clinical trials in patients with DVT alonehave validated treatment regimens that are similar to regimens used inpatients with both DVT and PE and in patients known to have only PE.None of these studies established the
Thrombolytic Therapy
Thrombolytic agents dissolve thrombi by activating a zymogen, plasminogen, to the active agent, plasmin. Plasmin, when in proximityto a thrombus or a hemostatic plug, degrades fibrin to solublepeptides.191 Circulating plasmin also degrades solublefibrinogen and, to some extent, several other plasma proteins.Streptokinase, urokinase, and tissue plasminogen activator (alteplase[tPA]) are the thrombolytic agents currently approved for clinicaluse in VTE.
Both streptokinase and urokinase have
Inferior Vena Caval Procedures
The major rationale for inferior vena caval filters is thepresence of a contraindication or complication of anticoagulation in anindividual with or at high risk for proximal vein thrombosis of thelower extremity. Less frequent indications include recurrentthromboembolism despite adequate anticoagulation, massivehemodynamically pulmonary embolism, chronic recurrent embolism withpulmonary hypertension, and the concurrent performance of surgicalpulmonary embolectomy or pulmonary endarterectomy.
The
Pulmonary Embolectomy
Pulmonary embolectomy continues to be performed in emergencysituations when more conservative measures have failed. If it isattempted, there is general agreement that a candidate meet thefollowing criteria: (1) massive PE (angiographically documented ifpossible); (2) hemodynamic instability (shock) despite heparin andresuscitative efforts; and (3) failure of thrombolytic therapy or acontraindication to its use. Operative mortality in the era ofimmediately available cardiopulmonary bypass has
Catheter Transvenous Extraction or Fragmentation of Emboli
A cap device has been developed that fits over an 8.5Fdouble-lumen, balloon-tipped steerable catheter to permit suctionextraction of PE under fluoroscopy with ECG monitoring.243 In a series of 26 patients undergoing catheter embolectomy, extraction was successful in 23 patients, with a mortality rate of27%.244 Two patients subsequently underwent openembolectomy. Over the same time in the same institution, six patientshad open embolectomy for acute PE with a mortality of33%.244 A report of
Paradoxical Embolism
The frequency of stroke and systemic embolism that is associatedwith VTE remains unknown. The complication most frequently occursthrough a patent foramen ovale.249 Echocardiography is auseful diagnostic tool when paradoxical embolism issuspected.250 Patency of the foramen ovale should besuspected when stroke is cryptogenic or occurs in younger people.Thrombolytic therapy may be useful as acute therapy in some patientswith paradoxical embolism.251 Recently, percutaneousclosure of patent foramen
Chronic Pulmonary Thromboembolism and Pulmonary Hypertension
A few individuals with PE (probably < 2%) do not resolve theprocess and subsequently develop pulmonary hypertension. Althoughprimary pulmonary hypertension and chronic thromboembolic pulmonaryhypertension demonstrate similar histologic appearances in themicroscopic pulmonary vessels,253 in the latter condition, the primary disorder is most likely obstruction of macroscopicpulmonary arteries by unresolved, organized emboli.254 Ifthe obstructing lesions are sufficiently proximal,
Primary Pulmonary Hypertension
There continues to be interest in treating primary pulmonaryhypertension with antithrombotic or fibrinolyticagents,260, 261, 262 although to our knowledge, there have beenno randomized trials evaluating such therapies in this condition.However, the use of warfarin in patients who did not respond to calciumchannel blockers appeared to result in improvedsurvival.263 A prospective controlled study continues tobe needed to confirm this observation.
Recommendations 1. Treatment of VTE 1.1. Effective Regimens
- 1.1.1.
We recommend that patients with DVT or PE should be treatedacutely with LMW heparin, unfractionated IV heparin, oradjusted-dose subcutaneous heparin (all grade 1A).
- 1.1.2.
When unfractionated heparin is used, we recommend that the doseshould be sufficient to prolong the APTT to a range that corresponds toa plasma heparin level of 0.2 to 0.4 IU/mL by protamine sulfate or 0.3to 0.6 IU/mL by an amidolytic anti-Xa assay (grade 1C+).
- 1.1.3.
In comparison to unfractionated heparin, LMW heparin offers themajor
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