Heart valve replacement Flashcards
What are the indications for aortic valve replacement?
Symptomatic patients with severe aortic stenosis should undergo aortic valve replacement to increase long-term survival. What classifies symptoms warranting consideration for valve replacement are increased fatigability and syncope combined with the echocardiogram findings are consistent with severe symptomatic aortic stenosis (AS). On echocardiogram, symptoms (eg, angina, syncope, exertional dyspnea) typically occurs when aortic valve area decreases to ≤1 cm^2. Severe AS is defined as aortic jet velocity ≥ 4.0 m/sec or mean transvalvular gradient ≥ 40 mmHg. The onset of symptoms in severe AS is associated with a significant increase in mortality and is an indication for aortic valve replacement to improve long-term survival. The average survival following symptom onset is 2-3 years without valve replacement. The onset of symptoms (exertional dyspnea, angina, presyncope or syncope) in patients with severe AS is associated with a significant increase in mortality.
When is Percutaneous balloon aortic valvotomy indicated for aortic valve replacement?
Percutaneous balloon aortic valvulotomy is considered only as a bridge to surgical or transcatheter aortic valve replacement in patients with severe symptomatic AS. It is associated with high rates of procedural complications (eg, stroke, myocardial infarction, acute aortic regurgitation) and does not improve long-term prognosis in severe AS.
What are the two primary types of valve replacements in aortic stenosis?
Mechanical valves: Highly durable but require lifelong anticoagulation.
Bioprosthetic valves: Made from animal tissue, shorter lifespan but do not require anticoagulation.
Why are bioprosthetic valves preferred in patients age ≥ 65 years?
Shorter life expectancy reduces the need for valve reoperation due to wear.
Avoidance of lifelong anticoagulation reduces bleeding risks.
Why are mechanical valves often chosen for younger patients?
Greater durability (last >20 years).
Reduced need for multiple reoperations over the patient’s lifetime.
What are the main risks associated with mechanical valve replacement?
Higher risk of thrombosis.
Requires lifelong anticoagulation, increasing bleeding risk.
What are the primary benefits of bioprosthetic valves?
Do not require lifelong anticoagulation.
Lower bleeding risk.
What is the ONLY anticoagulation suitable for patients who have a mechanical valve?
Because of the inherent thrombogenicity of the implanted prosthetic material and abnormal flow conditions induced by a mechanical prosthetic valve, all patients require lifelong anticoagulation after valve implantation to prevent thrombotic valve dysfunction (ie, valve thrombosis) and thromboembolic events (eg, stroke). Currently, a vitamin K antagonist, warfarin is the only acceptable oral anticoagulation agent.
There is insufficient evidence to support the use of a direct-acting oral anticoagulant (eg, apixaban, rivaroxaban).
Why is INR higher for mitral valve replacement when compared to aortic valve replacement?
The thrombotic risk associated with a mechanical valve implanted in the mitral position is increased compared with the aortic position (possibly from differences in local hemodynamic effects on the valves); therefore, the recommended intensity of anticoagulation (eg, goal INR) is higher for valves in the mitral position. Other factors that increase mechanical valve thrombotic risk include an underlying hypercoagulable state, prior thromboembolism, presence of atrial fibrillation or left ventricular systolic dysfunction, and use of an old-generation (ball-in-cage) valve.
What is the target INR for patients with an aortic valve replacement?
The thrombotic risk for a mechanical prosthetic valve in the aortic position is relatively lower than for the mitral position; therefore, an INR goal of 2.0-3.0 is appropriate for a mechanical prosthetic valve in the aortic position as long as no other factors are present to increase thrombotic risk (atrial fibrillation, left ventricular systolic dysfunction, prior thromboembolism, presence of a hypercoagulable state, use of an old-generation ball-in-cage valve).
What is the target INR for patients with an mitral valve replacement?
All patients with a mechanical prosthetic valve in the mitral position require a higher target INR of 2.5-3.5.
What requires adjustments to warfarin therapy?
Many things, such as prescribing amiodarone.
What is the first-line treatment for severe symptomatic mitral stenosis (MS)?
Percutaneous balloon mitral valvotomy (PBMV) is preferred if there is no left atrial thrombus or significant mitral regurgitation.
When is mitral valve replacement (MVR) preferred over PBMV in MS?
MVR is preferred if PBMV is contraindicated due to left atrial thrombus, moderate/severe mitral regurgitation, or heavily calcified valves.
At what mitral valve area (MVA) does intervention become necessary?
Severe MS is defined as MVA ≤1.5 cm²; intervention is typically indicated when symptoms are present.
What are the indications for mechanical vs. bioprosthetic valves in MVR?
Mechanical valves (preferred in <65 years, require lifelong anticoagulation). Bioprosthetic valves (preferred in >65 years, no lifelong anticoagulation).
What anticoagulation is required for mechanical mitral valve replacement?
Warfarin with an INR goal of 2.5–3.5.
What are contraindications to PBMV in mitral stenosis?
Left atrial thrombus, moderate/severe mitral regurgitation, or extensive valve calcification.
When is mitral valve replacement considered during another cardiac surgery?
If a patient with severe MS is already undergoing CABG or aortic valve surgery.
What is the most common cause of mitral stenosis worldwide?
Rheumatic heart disease.
What are the primary symptoms of severe mitral stenosis?
Dyspnea, fatigue, atrial fibrillation, hemoptysis, and right heart failure symptoms.
Why does severe mitral stenosis cause atrial fibrillation?
Left atrial dilation due to increased pressure leads to electrical remodeling and AF.
