Harrison's 262: Deep venous thrombosis & pulmonary thromboembolism Flashcards
VTE (venous thromboembolism) encompasses:
1) DVT
2) PE
Along with MI & CVA, what is the third major cardiovascular cause of death?
venous thromboembolism!
What is the most dangerous, acute risk of DVT?
Pulmonary embolus
What are 2 chronic complications of VTE?
#Chronic thromboembolic pulmonary hypertension #Postphlebitic syndrome
What has Medicare stated re: VTE events after total hip or knee replacements?
They are unacceptable “never events” and hospitals cannot be reimbursed for expenses related to them.
What is post-phlebitic syndrome?
Delayed complication of DVT that causes the valves in leg veins to become incompetent. Veins exude interstitial fluid, legs swell, sometimes ulcerate.
Worst part? We can’t fix it.
What is chronic thromboembolic pulmonary hypertension?
Does what it says on the box: pulmonary hypertension left over after a PE. It is often disabling & causes breathlessness.
So what’s so bad about DVTs?
Venous thrombi get dislodged & embolize to the lungs, where they hang out in the pulmonary arterial circulation like little punks. If there’s a patent foramen ovale or atrial-septal defect, they might go ANYWHERE in the arterial circulation, which becomes a real pain in the butt.
How does a PE kill ya?
Progressive right heart failure!
Wait, a PE gives you right heart failure?
Yes! Pulmonary vascular resistance goes up, RV tension rises & causes dilation. RV contraction keeps on going during LV diastole, squishing the poor little LV, which can’t fill up properly with blood. Cardiac output goes down, cardiac perfusion begins to suck, ischemia happens, and POOF circulatory collapse. Dead.
True or false: PE pretty much looks like everything else.
True! PE is super hard to detect when it occurs concurrently with heart failure or pneumonia.
What’s a good blood test to start with for VTE?
D-dimer! If it’s abnormally high, go straight to imaging.
Physical findings in a DVT:
Mild DVT: mild palpation discomfort in calf
Massive DVT: HOLY CRAP YOUR LEG IS HUGE. Also painful palpation of femoral vein. They might not be able to walk because of pain.
Differential diagnosis for DVT
# Ruptured Baker's cyst # Cellulitis # Post-phlebitic syndrome/venous insufficiency
Differential for PE
# Pneumonia, asthma, or COPD # CHF # Pericarditis # Pleurisy, costochondritis, musculoskeletal pain # Rib fracture, pneumothorax # ACS # Anxiety (maybe you're freaking out 'cause you have a PE?) # TOLD YOU PE LOOKS LIKE EVERYTHING ELSE!
Non-imaging ways to test for DVT or PE
#D-dimer, which isn't very specific. #Elevated troponins re: RV microinfarction. This is a pretty late in the game sign, though. #ECG: "S1Q3T3 sign" S-wave in lead I, Q-wave in lead III, and inverted T-wave in lead III. Pretty specific, but not sensitive.
Non-invasive imagine for PE/DVT
#Venous ultrasound #Chest x-ray #Chest CT #Lung scan #MRI
Criteria for diagnosing acute DVT via ultrasound:
1) Lack of vein compressability (major criterion!)
2) Vein does not “wink” when compressed in cross section
3) Failure to appose walls of vein due to passive distention
What does a thrombus look like on ultrasound?
Homogenous with low echogenicity
What will the doppler flow look like on ultrasound re: DVT?
Normal response: calf compression augments Doppler flow signal & confirms vein patency proximal & distal to doppler
Abnormal response: flow is BLUNTED with calf compression
Invasive imaging for DVT/PE
#Pulmonary angiography #Contrast phlebography (but venous ultrasound has basically replaced this)
What is meant by “primary vs. secondary” therapy for PE?
Primary: Clot dissolution with thrombolysis or removal by embolectomy
Secondary: Anticoagulation or placement of an IVC filter
Primary therapy should be reserved for…
…high risk patients!
Who are these “high risk” PE folks?
They are hemodynamically unstable, have RV dysfunction or enlargement, or high troponins from RV infarct!
Does anticoagulation dissolve the clot?
Nope. It just keeps the clot from growing while it resorbs naturally.
What drugs might we use to do this anticoagulation thing?
Heparin (fractionated or unfractionated), which we would then overlap with warfarin until therapeutic INR (which is between 2 & 3) is reached.
One more time, the target INR for warfarin in DVT? Hmmmm?
2-3!
True or false: Acute DVT patients MUST be admitted to the hospital.
False! They can often be managed as outpatients if they can do the whole unfractionated heparin shot thing.
