Prosthetic Valves



Patients that have had a valve replacement will have a scar. Usually this will be a midline sternotomy scar straight down the middle of the sternum indicating a mitral or aortic valve replacement or CABG). Less commonly a right sided mini-thoracotomy incision can be used for minimally invasive mitral valve replacement surgery.

Bioprosthetic versus mechanical

Valves can be either replaced by a bioprosthetic or a metallic mechanical valve. “Porcine” bioprosthetic valves come from a pig.

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. The INR target range with mechanical valves is 2.5 – 3.5.

 

Types of Mechanic Heart Valves

Starr-Edwards valve

  • Ball in cage valve
  • Very successful but no longer being implanted
  • Highest risk of thrombus formation

Tilting disc valve

  • A single tilting disc

St Jude Valve

  • Two tilting metal discs
  • The two discs mean they are called bileaflet valve
  • Least risk of thrombus formation

Mechanical Heart Valves

Major Complications

  • Thrombus formation (blood stagnates and clots)
  • Infective endocarditis (infection in prosthesis)
  • Haemolysis causing anaemia (blood gets churned up in the valve)

Mechanical valves cause a click

  • A click replaces S1 for metallic mitral valve
  • A click replaces S2 for metallic aortic valve

Transcatheter Aortic Valve Implantation (TAVI)

This is a treatment for severe aortic stenosis, usually in patients that are high risk for an open valve replacement operation. It involves local or general anaesthetic, inserting a catheter in to the femoral artery, feeding a wire under xray guidance to the location of their aortic valve, then inflating a balloon to stretch the stenosed aortic valve and implanting a bioprosthetic valve in the location of the aortic valve.

Long term outcomes for TAVI are still not clear as it is a relatively new procedure. Therefore in younger, fitter patients open surgery is still the first line option.

Patient that have a TAVI do not typically require warfarin as the valve is bioprosthetic.

Infective Endocarditis

This occurs in around 2.5% of patients having a surgical valve replacement. The rate is slightly lower for TAVI at around 1.5%. Infective endocarditis in a prosthetic valve has quite a high mortality of around 15%. This is usually caused by one of three gram positive cocci organisms:

  1. Staphylococcus
  2. Streptococcus
  3. Enterococcus

Patients with prosthetic valves used to be advised to take antibiotics for routine dental procedures to protect against infective endocarditis. This is no longer the case.

 

Last updated November 2018
WordPress Theme built by Shufflehound. Copyright 2016-2020 - Zero to Finals - All Rights Reserved