Prosthetic Valves

• Less commonly, a right-sided mini-thoracotomy incision can be used for minimally invasive mitral valve surgery
• Mitral regurgitation is the second most common indication for valve replacement
• Replacement of the tricuspid valve is very rare
• Bioprosthetic valves have a limited lifespan of around 10 years
• Mechanical valves have a good lifespan (well over 20 years) but require lifelong anticoagulation with warfarin
• St Jude valves

  • Consist of two tilting metal discs, called bileaflet valves. Of the three mechanical valves listed, the St Jude valve has the smallest risk of thrombus formation
• Starr-Edwards valves


  • Feature a ball in a cage, the ball moves away from the opening to let blood through, then moves back against the opening to prevent blood from regurgitating through the valve. They are no longer used due to the high risk of thrombus formation
• Patients that have had a valve replacement will have a scar, usually a midline sternotomy scar straight down the middle of the sternum, indicating a mitral or aortic valve replacement or a coronary artery bypass graft (CABG)
• Severe pathology of the aortic or mitral valves may be an indication for surgical replacement of that valve
• Types of heart valve replacements

  • Bioprosthetic
  • Mechanical
• Aortic stenosis is the most common valvular heart disease and the most common indication for valve replacement surgery
• The INR target range with mechanical valves is 2.5 – 3.5 (higher than the 2 – 3 target for atrial fibrillation)
• It is possible to hear a click when auscultating the heart sounds in a patient with a mechanical valve: A click replaces S1 for metallic mitral valves
• Tilting disc valves


  • Feature a single tilting disc
• Porcine bioprosthetic valves come from a pig
• A click replaces S2 for metallic aortic valves
• It is possible to hear a click when auscultating the heart sounds in a patient with a mechanical valve
• Transcatheter Aortic Valve Implantation (TAVI)

  Treatment for severe aortic stenosis, usually in high-risk patients for open valve replacement operation. Involves local or general anaesthetic, inserting a catheter into the femoral artery, feeding a wire under x-ray guidance to the location of the aortic valve, inflating a balloon to stretch the stenosed aortic valve, and implanting a bioprosthetic valve in the location of the aortic valve
• Patients with a TAVI do not typically require warfarin as the valve is bioprosthetic
• Major complications of mechanical heart valves

  • Thrombus formation (blood stagnates and clots)
  • Infective endocarditis (infection in the prosthesis)
  • Haemolysis causing anaemia (blood gets churned up in the valve)
• Long-term outcomes for TAVI still need to be clarified as it is a relatively new procedure. Open surgery is still the first-line option in younger, fitter patients
• Mechanical valves

  • The St Jude valve has the smallest risk of thrombus formation
• A click replaces S1 for metallic mitral valves
• Infective endocarditis occurs in around 2.5% of patients having a surgical valve replacement. The rate is slightly lower for TAVI at about 1.5%. Infective endocarditis in a prosthetic valve has quite a high mortality of about 15%. This is usually caused by one of three gram-positive cocci organisms: Staphylococcus, Streptococcus, Enterococcus