When heart valve disease progresses to the point that treatment by medicine does not provide relief from symptoms, a physician may recommend surgery to repair or replace the valve.1 If the heart valve cannot be repaired, a decision must be made as to what type replacement valve should be used. Typically, the choice is between a carbon-based mechanical valve and a tissue valve. The physician and patient will choose the type of valve while taking into account the risks and benefits, the patient’s overall condition, and preference.2,3
Tissue Heart Valves
Tissue heart valves (sometimes called “bioprosthetic” valves) are harvested from pig heart valves (porcine) or from the sac surrounding the heart of a cow (bovine). These tissues are treated and neutralized so that the body will not reject them. Some tissue valves are mounted on a frame or stent; while others are used directly (stentless).
The primary advantage of tissue valves is that they usually do not require long-term blood thinner therapy (e.g. warfarin). These medications reduce the rate at which blood clots are formed which can cause stroke or embolism, while creating an increase in risk of bleeding events. For most tissue valve patients, taking an aspirin a day is sufficient therapy.3 However, approximately 1/3 of patients with a tissue valve do not benefit from this, because they have a blood thinner requirement for other heart or vascular conditions.4
One of the objectives of a valve replacement procedure is to restore enough blood flow through the valve to the rest of the body to allow patients to maintain their active lifestyle.3 The more the blood flow is restricted through the valve for a patient, the more it may limit the possible level of activity (Figs. 1,2). Heart valve replacement with tissue valves can restore blood flow3,5-9 that may allow patients to return to a relatively normal lifestyle.
The primary disadvantage of tissue valves is their tendency to wear out and require replacement, especially in patients ≤ 65 years old (Fig. 3).10,11 The lifetime of tissue valves significantly depends on the patient’s age at the time of the valve replacement surgery. For patients less than 65 years old, some aortic tissue valves begin to fail after only 5 years10 and some mitral tissue valves begin to fail as early as 4 years after implant11. For patients greater than 65 years old, some tissue valves fail after 7 to 10 years.10 Risk factors that may increase the likelihood of failure include: “[…] conditions affecting calcium metabolism or when calcium containing chronic drug therapies are used, including children, adolescents, young adults, and patients on a high calcium diet or maintenance hemodialysis.”12
Fig. 3, Image of calcified aortic tissue valve that is worn out.
Homograft Valve (Ross Procedure)
The Ross Procedure is an option for younger patients who need aortic valve replacement.3 Unlike other aortic valve replacement procedures, the Ross procedure does not use a mechanical valve or a tissue valve taken from an animal. The Ross Procedure consists of two main steps.
- The first step is to replace a patient’s damaged aortic valve with his or her own pulmonary valve (autograft). Substituting the patient’s own pulmonary valve for the aortic valve is the only replacement valve that is truly alive and potentially able to last a normal lifetime without blood thinners or further surgery.13
Unlike other replacement valves, pulmonary autografts have been shown to grow with the rest of the body in young children.13
- The second step of the Ross Procedure is to replace the removed pulmonary autograft with a new pulmonary valve, typically a pulmonary homograft valve from a human donor.
There are newer methods of processing pulmonary homograft valves for the Ross Procedure that allow the tissue to perform better than standard processed tissues. SynerGraft® is one such new patented decellularization technology for processing human tissue. For instance, a comparison of Ross patients who received the CryoValve SynerGraft Pulmonary Human Heart Valve vs. standard processed pulmonary homografts at 10 years showed that patients who received standard processed pulmonary valves had 10% more incidences of valve explants due to failure, and 12% more re-interventions/reoperations compared to those who received the SynerGraft Pulmonary Human Heart Valve.14
If you are interested in the Ross Procedure and its unique ability to return patients to a normal life expectancy, ask your doctor about it and about the CryoValve SynerGraft Pulmonary Human Heart Valve.15 While Ross Procedures are not commonly performed by most surgeons, your surgeon can refer you to another surgeon who frequently performs this procedure.
See a short animated video of the Ross Procedure: Click Here to view video
Mechanical Heart Valves
The most widely used mechanical valves are made from pyrolytic carbon, which has been used for over 30 years in heart valve design. Most mechanical heart valves are bileaflet, meaning that they have two carbon “leaflets” to control the blood flow to a single direction.16
The primary advantage of mechanical valves is the likelihood of lasting a patient’s lifetime without the need for another valve operation because the valve has worn out.3,17 Mechanical valves have excellent blood flow performance3,18-21 which may benefit patient’s quality of life and ability for exercise.
A drawback of mechanical valves is the risk associated with the requirement for life long blood thinner (warfarin) therapy. However, when properly managed, rates are relatively low for both bleeding and clotting.3 Patients will need to determine their ability and desire to comply/maintain their blood thinner therapy and lifestyle requirements (e.g., regular blood tests, daily medications, and following a consistent consumption of leafy greens).3
Mechanical valves can sometimes be heard when opening and closing. The sound level varies with the patient. Among those noticing it, the sound can be reassuring,22 for others the sound can be disturbing.23
On-X Mechanical Heart Valves
The On-X Aortic Valve is a newer generation heart valve made of a unique material and design characteristics compared with earlier generations of mechanical heart valves. The On-X Aortic Valve is the only mechanical valve with FDA and CE approval as being clinically proven safe with significantly less blood thinner (warfarin).18,† The American Heart Association guidelines state that less blood thinner may be reasonable for patients with the mechanical On-X Aortic Valve.3 In a prospective randomized clinical trial, On-X Aortic Valve patients with a reduced blood thinner dose† had > 60% fewer bleeding events without an increase in risk of stroke.18 The On-X Aortic Valve, as a mechanical heart valve, has a much lower risk of reoperation than tissue valves, with the additional benefit of less bleeding risk than other mechanical aortic valves because of the significantly lower amount of blood thinner required.3,†
If you are under the age of 70 years and need aortic valve replacement, ask your doctor about the On-X Aortic Valve, the only mechanical valve that is both likely to last a lifetime3,17 and safer with less blood thinner.18 ,†
†After 3 months standard therapy. See On-X Prosthetic Heart Valve Instructions for Use.18
A patient’s choice regarding whether to receive a mechanical or tissue heart valve replacement involves weighing between the major advantages and disadvantages of both valve types.3 The ultimate goal of many patients is to improve their quality of life while minimizing risk. The patient’s life expectancy after valve replacement should also be considered during this decision. Some studies report mechanical valve patients may have a survival advantage compared with tissue valves patients in the 50-69 years age group; whereas in other studies, survival after valve replacement was not different for mechanical or tissue valve patients.24-26 The final choice is reached differently for each patient as many factors are considered with the guidance of his or her physician. See Table 1 to review the differences in valve durability, blood thinner, and patient survival after heart valve replacement.
Table 2: Tissue vs. Mechanical Heart Valve – Valve Lifetime, Blood Thinner, Bleeding Risk, and Survival.
|Mechanical Valve||Tissue Valve||Summary|
|All ages: Likely to last a lifetime.||Patients ≤ 65 years: Aortic valve failure as early as 5 years. Mitral valve failure as early as 4 years. ¥||Mechanical valves are likely to last a lifetime, but tissue valves have a risk of wearing out especially in patients ≤ 65 years.|
||Daily lifelong blood thinner medication.
|Short term blood thinner medication (3 to 6 months) with potential for lifelong requirement due to other conditions.
|Mechanical valves require blood thinner. Up to 1/3 of tissue valves may require blood thinner.
On-X Aortic Valve is the only mechanical valve FDA and CE approved requiring significantly less blood thinner.*
||From one study by Glaser et al., long-term survival was significantly better in patients aged 50 to 69 years who had a primary isolated aortic valve replacement with a mechanical valve than with a tissue valve. From one study by Goldstone et al., patient survival was significantly better at 15 years after implant for mechanical mitral valve patients up to 70 years of age compared with biologic (tissue) valve patients. (See Figs. 4, 5 below for graphical representation).|
¥ The average time before aortic tissue valve failure is 14.5 years with a standard deviation of 4.4 years.10 The average time before mitral tissue valve failure is 11.8 years.11
+ Aspirin is recommended for mechanical valves and is considered reasonable for tissue valves.3
* After 3 months standard therapy. See On-X Prosthetic Heart Valve Instructions for Use.18
Fig. 4. Long-term survival was significantly better in patients aged 50 to 69 years who had a primary isolated aortic mechanical valve replacement than with a tissue valve.24
Fig. 5. Patient survival was significantly better at 15 years after implant for mechanical mitral valve patients up to 70 years of age compared with biologic (tissue) valve patients.26
BV = Bioprosthetic (Tissue) Aortic Valve, MV = Mechanical Aortic Valve
- American Heart Association, Options and Considerations for Heart Valve Surgery. heart.org/heartvalvesurgery
- American Heart Association, Options for Heart Valve Replacement. heart.org/heartvalvereplacement
- Nishimura R et al., Circulation. 2017;135:e1159-95.
- Briffa N and Chambers J, Circulation. 2017;135:1101–3.
- Edwards Life Sciences Carpentier-Edwards PERIMOUNT Magna Pericardial Aortic Bioprosthesis Model 3000TFX Aortic Instructions for Use.
- Edwards Life Sciences Carpentier-Edwards PERIMOUNT Magna Ease Pericardial Aortic Bioprosthesis Model 3300TFX Instructions for Use.
- Edwards Life Sciences Carpentier-Edwards PERIMOUNT Theon Mitral Pericardial Aortic Bioprosthesis Model 6900PTFX Instructions for Use.
- Medtronic Mosaic Porcine Bioprosthesis with Cinch Advanced Implant System Instructions for Use.
- St. Jude Medical Trifecta Valve Instructions for Use.
- Wang M et al., Ann Thorac Surg 2017;104:1080-7.
- Kaneko T et al. J Thorac Cardiovasc Surg 2014; 147:117-26.
- Edwards LifeSciences. Surgical aortic pericardial valves. edwards.com/aortic-pericardial, downloaded on 07/05/2017.
- Stelzer. Complex Surgical Repair and Reconstruction of the Aortic Valve and Root. www.ps4ross.com/ross-procedure
- CryoLife Data on File – CryoValve® SG Pulmonary Human Heart Valve Post-Clearance Study.
- David TE. Circulation 2009;119;207-9.
- Rajashekar P. J Pract Cardiovasc Sci 2015;1:289-93.
- van Geldorp M et al., J Thorac Cardiovasc Surg. 2009;137:881-6.
- On-X Prosthetic Heart Valve Instructions for Use.
- St. Jude Medical Physician’s Manual Mechanical Heart Valve.
- CarboMedics Prosthetic Heart Valve Instructions for Use.
- Medtronic Open Pivot Heart Valve Instructions for Use.
- CryoLife interview with Mischel S., an On-X Mitral Valve recipient, 2016. Data on file.
- Korteland N et al., Interact CardioVasc Thorac Surg 2016 Jun;22:723-8.
- Glaser N et al., Euro Heart J. 2016;37:2658-67.
- Zhao DF et al., Ann Thorac Surg 2016;102:315–27.
- Goldstone AB et al. N Engl J Med 2017;377:1847-57.