There are three main groups of prosthetic heart valves: mechanical valves, bioprosthetic valves, and homo- and autografts. Which prostheses are the most common? What are they made of and what are their main elements? Find out in this lesson presented by Samir Sulemane, a Senior Clinical Scientist and Echocardiography Expert at Royal Brompton and Harefield NHS Trust, UK.
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Echocardiography of prosthetic heart valves is much more demanding, both to perform and to interpret, compared to the assessment of native heart valves. Learn how to use tools such as 2D, 3D, and transesophageal echocardiography in order to become a skilled decision-maker who can confidently talk to any cardiologist or cardiac surgeon about your patient’s prosthetic valve problem.
Is your patient’s prosthetic valve in tip-top shape? Master echo to thwart complications and confidently assess their valves.
The heart has four valves, the pulmonary and tricuspid valves on the right, and the aortic and mitral valves on the left. Valvular heart disease occurs when one or more of the heart valves is damaged. If heart valve disease progresses to the point where medical treatment does not provide symptomatic relief, the patient may be recommended for surgery to repair or replace the valve. In this Medmastery lesson we'll cover the different types of prosthetic heart valves that are used for valve replacement.
The ideal prostheses should mimic the characteristics of a normal native valve, including excellent hemodynamics, implantability, and durability. It should also be highly resistant to platelet and thrombus deposition, structural wear and tear and mechanical failure. Unfortunately, this ideal prosthetic valve does not exist, and each of the current available ones has inherent limitations. Broadly speaking, prosthetic heart valves are divided into three groups.
The first group is mechanical valves made exclusively of synthetic materials. The second group consists of bioprosthetic valves, and includes stented, stentless and percutaneous ones. As the name indicates, stented bioprostheses are mounted on a frame or stent, while stentless valves have no stent, and are fixed with special glue. Percutaneous valves are made of bovine pericardium mounted in an expandable stent. The last group includes homografts and autografts.
Homografts are cryopreserved human aortic roots and valves, whereas autografts are harvested from the patient's own body. Currently, the most widely used prostheses are the mechanical, stented bioprosthetic and percutaneous valves. So this masterclass will mainly focus on these three. Mechanical and stented bioprostheses have three main components: the sewing ring, supporting frame or stent, and leaflets. The sewing ring allows the prostheses to be secured to the patient's tissue annulus.
It has a silicone band that supports tissue ingrowth to the surrounding anatomy. The supporting frame is composed of alloy or polymer materials that absorb some of the forces acting on the leaflets. The leaflets are made of carbon for mechanical valves, and tissue for bioprosthetic valves. And they can open and close to allow blood flow across the chambers. On the other hand, percutaneous valves are composed of a trileaflet bovine pericardial tissue valve mounted in an expandable stainless-steel stent. You will encounter patients with all different valve types, so the rest of this chapter will focus on differentiating between them with echocardiography. Let's get started.