Heart Valve Replacement

Some pro's and con's related to prosthetic heart valve choice are detailed in the table below. These issues have been discussed in detail and referenced in the preceding and following paragraphs. Red text indicates the main points associated with each valve choice.

Pro for Replacement*			Con for Replacement*
Mechanical	Tissue	On-X Valve	Mechanical	Tissue	On-X Valve
Lifetime durability	50% or more of patients do not need blood thinner (anticoagulant)	Lifetime durability	Must take blood thinner (anticoagulant)	Up to 50% or more of patients eventually must take blood thinner (anticoagulant)	Must take blood thinner (anticoagulant) but it could be reduced for some patients.
Lower reoperation rates	Quiet-do not usually make noise	Lower reoperation rates	Make a clicking noise that is bothersome to some patients	Decreased survival rates	Many patients report not hearing the valve click
Better survival rates	Only homografts are efficient in small sizes	Better survival rates	Increased chance of bleeding	Repeat operation every five to fifteen years with associated risks, discomfort and recovery	Potential for reduced bleeding through patient self-testing of INR
Better efficiency in small sizes	----	Possibility of reduced blood thinner	----	Increased chance of bleeding for patients taking blood thinner	---
----	----	Best efficiency in small sizes	Can cause stroke	Can cause stroke	Can cause stroke
----	----	Lower complication rates	Scar tissue (pannus) ingrowth	Less efficient in small sizes	----
----	----	Quiet design	----	Scar tissue (pannus) ingrowth	----
----	----	Scar tissue ingrowth not observed

Red text indicates the main points associated with each valve choice.

Mechanical heart valves

Mechanical heart valves Pro's:

Last a lifetime when anticoagulation is well controlled and there are no related complications.
Reoperation rates are lower than those of tissue valves (Table 5).
Survival rates are better than tissue valves (Tables 3a and 3b).
More efficient functioning (hemodynamics) in small aortic sizes than stented tissue products (Table 8)
For the On-X heart valve, turbulence is reduced, pivots are washed thoroughly and the leaflets are protected. Result:
- Complication rates are lower
- Efficiency (hemodynamics) is the best in smaller sizes over other mechanical heart valves and most tissue heart valves (Tables 3-5 and Table 7).
- The only valve to offer leaflet guards to protect against pannus (scar tissue) ingrowth is the On-X valve.
- The On-X heart valve is quiet because of decreased turbulence and design advantages.
- There is the possibility of reduced anticoagulant.^57-60
- The On-X heart valve is the only valve with a government approved reduced anticoagulation clinical trial.⁶⁰

Mechanical heart valves Con's:

Fluctuations in anticoagulant medication level on the low side (INR less than 2) for older design valves can cause clots to form which can block valve motion (thrombosis) or can travel and cause damage to vital organs (brain:stroke, etc.)
Fluctuations on the high side (INR more than 3.5) can cause bleeding in vital organs such as the brain especially in patients over 70 years old.¹⁵
Pannus ingrowth can occur and block leaflet motion leading to thrombosis with conventional mechanical prostheses. On-X has leaflet guards to inhibit pannus ingrowth.
Valve noise can cause sleep disturbance

Stented tissue heart valves

Stented tissue heart valves Pro's:

As many as 50% of tissue heart valve recipients do not require anticoagulant medication for a lifetime but do have to take it for about three months after surgery.⁴⁷
Tissue heart valves are mostly quiet.

Stented tissue heart valves Con's:

Stented tissue valves wear out, calcify (build up calcium) and fail starting as early as five years postoperatively and extending through 15 years. The greatest period of decline starts at about 8 years (Figure 8).⁸
As many as 50% of tissue heart valve recipients are placed on anticoagulant medication for other medical conditions even though the valve does not require it.⁴⁷ For example, arrhythmia (irregular heart beat) may make anticoagulation necessary.¹⁵
Because of tissue heart valve failure starting at 8 years, as many as 3 or 4 operations could be required in a lifetime depending on patient age at the first operation. Reoperation risks increase with each valve surgery and with increasing age (Table 6).^{53, 54}
Unpleasant effects of cardiac surgery from cutting the breastbone (sternum) spreading the ribs, processing the blood in the heart-lung machine and manipulation of the internal tissue are pain which can last several weeks or longer, possible fatal complications, reduced activity for weeks/months, disruption of a normal lifestyle, etc. Repeat operations will increase risks and discomforts at a later age when the body is less able to cope with extensive manipulations. Conservatively, the valve lifetime should be longer than patient life-expectancy.
Pannus ingrowth occurs in tissue valves and can disturb valve function.¹¹

Stentless tissue heart valves

Stentless tissue heart valves are pig aortic roots (aortic valve and piece of aorta) that have been chemically treated and reinforced with a pliable exterior cuff.

Stentless tissue heart valves Pro's:

Lack of a stent (frame) opens up more area to blood flow giving better efficiency to the valve especially in small aortic sizes.^35,36,43
As many as 50% of tissue valve recipients do not require anticoagulant medication for a lifetime.⁴⁷
Tissue valves are mostly quiet

Stentless tissue heart valves Con's:

May not wear out as fast as stented tissue valves, but will do so eventually.⁸
May have central regurgitation if not positioned correctly during procedure.^35,36,43 Significant regurgitation (leakage) may cause physical limitations after surgery.
Required reoperation increases risks with each procedure and with advancing age.^53,54

Homografts

Homografts are human aortic roots that have been harvested from donors and deep frozen for preservation.

Homograft tissue heart valves Pro's:

Best efficiency of all valves on the market, tissue and mechanical.^62-64
As many as 50% of tissue heart valve recipients do not require anticoagulant medication for a lifetime.⁴⁷
Tissue heart valves are mostly quiet.

Homograft tissue heart valves Con's:

Limited availability due to small donor pool.
May have central regurgitation if not positioned correctly during procedure.^63,64 Significant regurgiation (leakage) may cause physical limitations after surgery.
Required reoperation increases risks with each procedure and with advancing age.^53,54
No valves for the mitral position.

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