The evolution of prosthetic heart valves Introduction Since its first use in 1952 the practise of prosthetic heart valves has risen dramatically. Around 65,000 heart valves are repaired or replaced annually in the United States alone [1]. The demand for better performing, more efficient heart valves is ever increasing. Since the 1950’s over 80 different models for prosthetic heart valves have been developed [2]. In this report I will be reviewing some of the more well-known designs and how they have evolved and changed to give us the designs we have today, and what we might expect to see in the future. Anatomical Background The human heart consists of four chambers, the left and right atria and the left and right ventricles. The heart also has four valves, as shown in Figure 1. The primary function of the heart valves is to ensure blood flow in only one direction by preventing back flow. However certain diseases or complications can cause the heart valves to malfunction, preventing the heart from operating efficiently. Epidemiology of valvular diseases Diseases affecting the heart valves will result in either: Regurgitation – Regurgitation occurs when the heart valve closes incompletely causing the valve to leak and allow back flow of the blood. Stenosis – Stenosis occurs when the valve does not open completely, causing the blood flow to be restricted. Both of these malfunctions could have major consequences if not properly addressed such as heart failure, stroke, sudden cardiac arrest or blood clots [3]. In such cases the valve would need repair or complete replacement. Evolution of prosthetic heart valves Before the 1950’s the need for prosthetic heart valves was recognised but was out of reach of scientists. However, ... ... middle of paper ... ...ge success, with very good durability, hemocompatibility, small bulk and uniform design. The durability was down to the material pyrolyte being used and the low levels of structural complications. Superior haemodynamic properties and the uniform design allowed the valve to be relatively good at resisting thrombus formation due to the minimisation of flow disruption, although anticoagulation therapy was still required. Bio-prosthetic heart valves In the mid to late 1960s an entirely new type of prosthetic heart valve was introduced, the bioprosthetic heart valve. Instead of purely synthetic materials, bioprosthetic heart valves consist of biological tissue, sometimes a combination of biological and synthetic materials are used. There are many types of bioprosthetic heart valves, the main categories include: Homograft valves – These are valves taken from cadavers,
Transcatheter aortic valve replacement or TAVR is the latest technology used principally for the treatment of aortic stenosis, a condition in which one of the major valves of the heart, the aortic valve, becomes tight and stiff, usually as a result of aging (3). Since many patients who need aortic valve replacement for aortic stenosis are too sick to undergo major valve replacement surgery, they are unable to get the treatment they need. With the transcatheter aortic valve, this issue is bypassed because this valve can be implanted in the heart by accessing the patient’s heart through an artery in the groin. The valve can be inserted through a wire that can be pushed to the heart and the old valve is simply pushed to the side when the new valve is implanted. This technology has been in use in the US with Edwards’ Sapiens valve since 2011 and has saved the lives of many patients with aortic stenosis (4). Medtronic’s CoreValve uses similar technology and has won patent fights in Europe and has been in use internationally. However, within U.S., Medtronic has not been...
Some advantages of the Total Artificial Heart include: 9.5 L/min of increased blood flow through both ventricles, faster bridge-to-transplant, and it eliminates complications caused by a diseased heart, such as kidney and liver failure. (“Syncardia”) “The first Total Artificial Heart implant was performed in Richmond, Va. on April 4, 2006 by a cardiac surgery team at VCU (Virginia Commonwealth University) in the Pauley Heart Center”(Lepley p.1). The major point to remember is that this is a mechanical heart that totally replaces a person’s own heart.
Wand, O., Prokupetz, A., Grossman, A., & Assa, A. (2011). Natural history of mitral valve prolapse in military aircrew. Cardiology, 118(1), 50-4. doi:http://dx.doi.org/10.1159/000324313
The thickening of the muscle cells do not necessarily have to change the size of the ventricles, but can narrow the blood vessels inside the heart. Hypertrophic cardiomyopathy can be grouped into two categories: obstructive HCM and non-obstructive HCM. With obstructive HCM, the septum (the wall that divides the left and right sides of the heart) becomes thickened and blocks the blood flow out of the left ventricle. Overall, HCM usually starts in the left ventricle. HCM can also cause blood to leak backward through the mitral valve causing even more problems. The walls of the ventricles can also become stiff since it cannot hold a normal amount of blood. This stiffening causes the ventricle to not relax and entirely fill with
With this improvement, Dr. Willem J. Kolff, the head of the artificial developmental program at the University of Utah, and Dr. William DeVries, the head cardiac surgeon at the University of Utah, decided to take this device further. They wanted to develop a heart based on the heart tested in farm animals, to place into a human. This was done with the help of Dr. Robert Jarvik who developed the Jarvik-7. This device was made of plastic and aluminum. With all that they had accomplished, the staff at the University of Utah’s artificial development program still had to wait 2 years before they found the right candidate for the project.
The Burden of the disease is high with a prevalence of 3.4% 2. With the progressive nature of the disease and the increased severity of the symptoms made the surgery the gold standard for symptomatic AS patients ,however up to 30% of cases are considered too high risk for classical valve replacement surgery and remain untreated and experiencing poor prognosis . Fortunately , with the introduction of TAVR its offer a valuable option for the inoperable or at high risk of surgery patients3..the annual eligible candidate for this procedure expected to be 27,000 in 19 European countries and North America according to recent meta-analysis an...
Prosthetic heart valve replacement is performed in several hundred thousand patients per year worldwide and is recommended for many patients with severe valvular heart disease. Bioprosthetic heart valves and mechanical heart valves are the two major valve types. Mechanical valves are more durable than bioprosthetic valves but require lifelong anticoagulant therapy with vitamin K antagonists (warfarin) due to persistent risk of thrombosis and stroke. Warfarin has a narrow therapeutic window and requires frequent monitoring such as international normalized ratio (INR) and restrictions on food, drugs and alcohol. Due to limitations of warfarin many patients prefer bioprosthetic valve replacement rather than a mechanical valve, despite the risk of premature valve failure and repeated valve replacement surgery with bioprosthesis.1 Warfarin works by inhibiting coagulation factors II, VII, IX and X, as well as proteins C and S and hence reduces synthesis of active clotting factors.4
Prosthetics (pronounced prahs-THEH-tiks) is the branch of medicine that deals with the artificial replacement of a missing body part. A prosthesis (pronounced prahs-THEE-sis) is the general term for the artificial part itself that replaces the body part usually lost to disease or injury. Prosthetics has a long history, and recent design advances that use battery power and new lightweight composite materials are making prostheses better and easier to use.
The heart is divided into two halves, which are further divided into four chambers: the left atrium and ventricle, and the right atrium and ventricle. Each chamber on one side is separated from the other, by a valve, and it the closure of these valves that produce the “lubb-dubb” sound so familiar to us.
The materials in prosthetic limbs have always evolved along side technology, usually changing for the better. Prior to the development of electronics and plastics,
that can be implanted along with stent grafts during endovascular repair (US Fed News, 2006).
The main topic of this essay will be about the in-depth research into medical prosthetics
the heart ventricles during diastole. At the time of the cardiac cycle during diastole the valves between the two
Aortic stenosis is a narrowing of the aortic valve. The aortic valve is a gate-like structure that is located between the lower left chamber of the heart (left ventricle) and the blood vessel that leads away from the heart (aorta). When the aortic valve is narrowed, it does not open all the way. This makes it hard for the heart to pump blood into the aorta and causes the heart to work harder. The extra work can weaken the heart over time and may lead to heart failure.
Heart disease can take many forms. The form of heart disease I am focusing on is coronary disease. Different arteries supply different areas of the heart with oxygenated blood. If one or more of these arteries become narrowed or clogged as a result of coronary artery disease, or atherscelorosis the artery cannot fully supply the part of the heart it is responsible for. The heart is an effective pump only when good blood supply is maintained to all heart muscles.