Rapid Review·Cardiovascular
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Valvular Heart Disease
T1Must knowProsthetic Heart Valves
Focus on
Mechanical valves last forever and need warfarin forever (INR 2–3 aortic, 2.5–3.5 mitral or with risk factors; never a DOAC); bioprosthetic valves wear out in 10–15 years but need no long-term anticoagulation. Prosthetic dysfunction is heart failure, a new murmur, an embolus, hemolysis or fever — echo it, and remember every prosthetic valve gets endocarditis prophylaxis.
Key takeaways
Choosing the prosthesis
Mechanical valve
lasts a lifetime but needs lifelong anticoagulation.Bioprosthetic valve
needs anticoagulation for only 3 months but degenerates, so it may need replacing every 10 years.| Mechanical | Bioprosthetic | |
|---|---|---|
| Who | Under 50 for an aortic valve, under 65 for a mitral valve; already anticoagulated; high risk for a repeat operation | 65 or older; high bleeding risk; pregnant or planning pregnancy |
| Advantage | Long lifespan | Anticoagulation for only 3 months |
| Disadvantage | Lifelong anticoagulation | Short lifespan (sclerotic degeneration, about 10 years) |
Anticoagulation
Every mechanical valve
needs lifelong anticoagulation to prevent valve thrombosis and thromboembolism (stroke).Warfarin is the only acceptable oral agent
direct oral anticoagulants lack evidence.Target international normalized ratio (INR) 2.5 to 3.5
for a mitral valve, an aortic valve with a risk factor, or an old-generation aortic valve.- Risk factors: atrial fibrillation, left ventricular dysfunction, prior thromboembolism, a hypercoagulable state.
Target INR 2.0 to 3.0
for an aortic valve without risk factors; some new-generation aortic valves accept a lower target.Why mitral is higher
the mitral position carries the higher thrombotic risk, hence the higher target.Aspirin
add low-dose aspirin only for another strong indication (severe coronary disease).Prosthetic valve dysfunction
Paravalvular leak
regurgitation around the valve from dehiscence off the annulus.- More often with mechanical valves, from annular degeneration or endocarditis.
Transvalvular regurgitation
regurgitation through the valve.- More often with bioprosthetic valves, from cusp degeneration or thrombus that stops closure.
Obstruction
a thrombus or a cusp that fails to open.Presentation
heart failure, thromboembolism, a new murmur, and a macroangiopathic hemolytic anemia.Diagnosis and treatment
echocardiography confirms it and surgical replacement treats it.Prosthetic valve thrombosis
Cause
usually inadequate anticoagulation of a mechanical valve, which clots far more readily than a bioprosthesis.Classic case
a patient with a mechanical mitral valve who stops anticoagulation and develops dyspnea with bibasilar crackles has valve thrombosis.Presentation
usually obstruction (mimicking stenosis), rarely regurgitation, with a new murmur and heart failure.Where the clot goes
a left-sided (mitral or aortic) thrombus embolizes systemically.- Transient ischemic attack, stroke, myocardial infarction, bowel or limb ischemia.
- A tricuspid thrombus causes pulmonary embolism.
Diagnosis
transthoracic echocardiography shows the thrombus and the dysfunction.Treatment
anticoagulation (heparin); immediate surgery for severe heart failure or a large thrombus.A 45-year-old with a mechanical mitral valve stopped warfarin two weeks ago and now has dyspnea, bibasilar crackles and a new murmur. What is the diagnosis, and what INR range should he have been kept in?
Prosthetic valve thrombosis from inadequate anticoagulation, presenting as obstruction with heart failure. Confirm with transthoracic echocardiography; treat with heparin, and immediate surgery for severe heart failure or a large thrombus. A mechanical mitral valve needs INR 2.5 to 3.5 on warfarin.
How it's tested
A 45-year-old with a mechanical mitral valve and no other risk factors — target INR: 2.5–3.5 (mitral position); an aortic mechanical valve alone would be 2.0–3.0.
A mechanical-valve patient is switched from warfarin to apixaban for convenience: wrong — DOACs are contraindicated with mechanical valves.
A 72-year-old woman with a bioprosthetic aortic valve, sinus rhythm: aspirin alone; no long-term warfarin.
Dyspnea, a new systolic murmur and anemia with schistocytes, high LDH and low haptoglobin five years after mitral replacement: paravalvular leak with mechanical hemolysis — TEE, then repair.
Fever and a new paravalvular jet two months after valve replacement: prosthetic valve endocarditis — blood cultures, TEE, vancomycin + rifampin + gentamicin, and surgery.
Which valve for a 28-year-old woman who wants children: bioprosthetic (or repair) — mechanical valves need warfarin, which is teratogenic.
Go deeper
Guidelines: 2020 ACC/AHA Valvular Heart Disease Guideline — Prosthetic Valves
Related Step 2 pages: Prosthetic Heart Valves, Infective Endocarditis, Aortic Stenosis, Mitral Regurgitation, Coronary Artery Bypass Grafting
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