Prosthetic Valves in PACES

First look for scars....

For a mitral valve replacement:
There is a midline sternotomy scar/lateral thoracotomy scar
There is a metallic S1 click representing closing of the prosthetic mitral valve
There is a metallic opening snap in diastole
S2 is normal

For an aortic valve replacement:
There is a midline sternotomy scar
S1 is normal and followed by an opening click of the prosthetic aortic valve
There is a metal prosthetic click instead of S2, representing closure of the aortic valve.

If the valve is bioprosthetic rather than metallic the heart sounds may be normal.



What types of valves do you know of?

• broadly, replacement valves are either mechanical prosthesis (ie made of man-made material) or bioprosthetic (ie either from human or animal source, most commonly porcine)
• mechanical prosthesis include bileaflet tilting discs (such as the St Jude), monoleaflet tilting disc (such as the medtronic hall) or ball and cage (Starr-Edward)
• bioprosthetic valves include porcine aortic valves, valves made from bovine pericardium and human cadaveric donations.
• more info here

How would you choose if a patient received a mechanical prosthesis or a bioprosthetic valve?

• decision made by informed patient, cardiologist and cardiac surgeon
• mechanical valve: lasts for longer but requires anticoagulation
• bioprosthetic valve: lifespan of around 10yrs but no need for anticoagulation
• based on these facts, European Society of Cardiology suggests:
• bioprosthetic valves in over 65s (for mitral valves) and over 70s (for aortic valves), for those at risk of haemorrhage/likely to have poor compliance with anticoagulation and for young women contemplating pregnancy
• mechanical prosthetic valve in everyone else, plus maybe the elderly already on long-term anticoagulation
• more info here

What would the target INR be for a mechanical prosthetic valve?

• depends both on the valve type and the patient-associated risk
• patient-associated risk factors include mitral or tricuspid valve replacements, AF, mitral stenosis, EF <35%, previous thromboembolism
• lowest risk valves include St Jude medical; highest include Starr-Edwards
• target INRs range from 2.5 to 4.
• more info here

What complications are associated with valve replacements?

• prosthetic valve thrombus - up to 5% per year - diagnose with TOE - treat with either surgery or thrombolysis
• infective endocarditis - highest risk in first 3 months and up to 3% in first year;  after 12 months risk falls to around 0.4% per year
• LVF
• haemolysis - usually mild, may require iron tablets
• bleeding due to anticoagulation
• more info from up-to-date - requires Athens