Lecture 25 - Venous Thromboembolism Part 4

what is an example of a patient case where they are at high risk of thrombosis but anticoagulants are contraindicated

someone who just had major bleeding e.g. intracranial hemorrhage, GI bleed AND the have a blood clot

what is an inferior vena cava filter

inserted into inferior vena cava → catch clots that might embolize of might be headed to lungs

only used for DVT patients (cannot be used for PE → already past that point)

what are the effects of inferior vena cava filters

Reduce the risk of fatal PE in the short-term

Increase the risk of DVT in the long term

Presence of a permanent IVC filter may require long-term anticoagulation – foreign body in vasculature

what is post thrombotic syndrome

DVT complication

Destruction of back-flow valves, poorer circulation – chronic changes

Occurs in nearly one-third of patients within 5 years after unprovoked DVT

what are s/s of post thrombotic syndrome

Pain

Edema

Hyperpigmentation

Eczema

Varicose collateral veins

Venous ulceration

Severe PTS can lead to intractable, painful venous leg ulcers requiring on-going nursing and medical care

how do pain symptoms of post thrombotic syndrome compare to DVT

PTS: ‘not as bad as when I had the clot’, ‘worse after I’ve been on my feet’, ‘dull ache’

DVT: ‘just like the first time’, ‘worst it has ever been’

how do swelling symptoms of post thrombotic syndrome compare to DVT

PTS: Usually will decrease after feet are elevated (above level of the heart), gets worse as leg is used / day evolves

DVT: Present at all times

how does the appearance of post thrombotic syndrome compare to DVT

PTS: Chronic changes

DVT: Red, Warm

how is PTS managed

leg elevation (45 degrees - above heart)

compression stockings

Start in ~ 1 month, wear during waking hours

when should patients avoid leg elevation and compression stockings

arterial insufficiency, intermittent claudication, uncontrolled heart failure, infection in area covered by stocking

what are the benefits of compression stockings

symptomatic improvement only

does NOT reduce PTS or have reduction in outcomes

what is Chronic Thromboembolic Pulmonary Hypertension (CTEPH)

Serious complication of PE

Thromboemboli may fail to resolve and organize into fibrotic deposits, permanently occluding pulmonary arteries

• pulmonary arteries become more narrow and pressure increases → increases pressure of right ventricle

Right heart failure can frequently occur

what are s/s of Chronic Thromboembolic Pulmonary Hypertension (CTEPH)

Initial phase of disease often asymptomatic and followed by progressive dyspnea and hypoxemia

Progressive condition associated with mortality rates of 4–20%

what is the main purpose of treating an existing clot

applies to DVT and PE

Must treat with quick acting anticoagulant at full therapeutic dosing

Most effective strategy is to prevent VTE

what is the main setting where VTE prophylaxis is used

Primarily in hospitalized setting

Surgical (& medical) population (most common = orthopedic surgeries)

Consider for every hospitalized patient

when is VTE prophylaxis not indicated

patient fully mobile

length of stay less than 72 hours

minor surgery

age less than 60 years

when is VTE prophylaxis contraindicated

active bleeding

thrombocytopenia

severe hypertension

bleeding disorder

what are options for VTE prophylaxis

tinzaparin

enoxaparin

fondaparinux

rivatoxaban

apixaban

unfractioned heparin

what drug for VTE prophylaxis may be used in orthopedic population

rivaroxaban

which VTE prophylaxis drugs are not used in a general surgery population or a general medicine population

rivaroxaban

apixaban

what is Superficial Thrombophlebitis or Superficial Vein Thrombosis (SVT): Treatment

PRN use of topical NSAIDs, compresses (warm & cool), compression stockings

Therapeutic Anticoagulation x3 months (certain criteria)

Prophylactic Anticoagulation with rivaroxaban 10mg daily or fondaparinux 2.5mg daily (certain criteria)

what are criteria for therapeutic anticoagulation x 3 months for Superficial Thrombophlebitis or Superficial Vein Thrombosis (SVT)

Concomitant VTE

SVT within 3cm saphenofemoral junction (SFJ) or saphenopopliteal junction (SPJ) → clot is really close to where it connects to deep vein

what are criteria for prophylactic anticoagulation x 45 days for Superficial Thrombophlebitis or Superficial Vein Thrombosis (SVT)

SVT > 5cm long that is 3cm away from SFJ or SPJ

If severe symptoms or risk for extension (consider)

is the mitral or aortic valve more thrombogenic

mitral valve → more complex

mitral valve surgeries are riskier, worse long term outcomes compared to aortic valve surgeries

what are common reasons for valve replacement surgery

Stenosis

Stenosis

Prolapse

what is stenosis

mechanical obstruction to blood flow, net result of reduced valve orifice area

Mitral, Aortic

what is regurgitation

backward flow of blood, ‘leaky’ valve, may be called “insufficiency”

Mitral, Aortic

what is prolapse

to fall or slip down

Mitral

what are the 2 types of valves that can be implanted

Bioprosthetic (Tissue)

Prosthetic (Mechanical)

what is a bioprosthetic (tissue) valve

from a pig

Less durable, up to 30% failure rate at 10-15 years

Less thrombogenic

less ideal for younger patients → will need to replace

what is a prosthetic (mechanical) valve

3 generations: Ball cage, single leaflet, double leaflet

More durable

More thrombogenic → need to be on warfarin

why are valves thrombogenic

Tissue injury with implantation (highest risk in first 3 months)

Stasis of blood in the atria / ventricle

Presence of foreign body unable to combat clotting (not living tissue capable of releasing tPA, etc.)

Shear force of blood flow across the valve

what medication class might be used for Bioprosthetic Valves

Anticoagulant for some, antiplatelet long-term

what is prescribed after a mechanical heart valve is inserted

warfarin for all

antiplatelet (ASA) often co-administered

Do NOT use DOACs for those with mechanical heart valves

what is prescribed after a tissue valve is inserted

Antiplatelet alone vs. Warfarin for 3 months followed by Antiplatelet

what is prescribed if a bioprosthetic aortic valve is inserted

ASA 50-100 daily

what is prescribed after a bioprosthetic mitral valve is inserted

warfarin x 3 months (INR 2-3) then ASA

what is prescribed after a mechanical aortic valve is inserted

warfarin (INR 2-3)

sometimes cross-over with LMWH until warfarin is therapeutic

what is prescribed after a mechanical mitral valve is inserted

warfaring (INR 2.5-3.5)

sometimes cross-over with LMWH until warfarin is therapeutic

when might chronic anticoagulation therapy need to be interrupted

invasive procedure or surgery wherein bleeding will occur if anticoagulated

how should warfarin be managed if patients need surgery

Must hold warfarin 5 days prior to procedure, then will take ≥ 4 days following procedure to achieve therapeutic anticoagulation

Depending on risk of thrombosis may need to use LMWH (subcutaneously) given the delay with warfarin and hence time with sub-therapeutic anticoagulation

how should DOACs be managed if patients need surgery

No need for bridging with LMWH, simply hold / restart DOAC (~4 days off total)

where can you check to find out if a procedure is considered high bleed risk

Thrombosis Canada Procedure Bleeding Risk

how should warfarin be re-started after it was held

give dose at 1.5 maintenance dose for 3 days then assess INR (given delay in onset)

LMWH dosing as per pre-procedure, acknowledging quick onset, to stop once INR target achieved

how should DOACs be restarted after being held

start once hemostasis intact

when considering anticoagulants, is a clot risk or bleed risk considered more important

clot risk

True or False?

UFH, LMWH and fondaparinux are indirect anticoagulants because they bind to antithrombin to then go onto reduce the activity of clotting factors in the circulation; they act quickly because they affect clotting factors in the circulation.

True