Disadvantages

Artificial Heart Valves

Within 10 years of preliminary heart valve replacement
50-60% of patients will face problems like prosthesis - associated problems requiring re-operation
Several problems occurred like:
Valve-related complication (thromboembolism, thrombosis, and secondary anticoagulation-related haemorrhage)
Endocarditis and structural dysfuntion (failure or degeneration of the prosthetic biomaterials)
Nonstructural dysfunction during surgical implantation (perivalvular leak and biological integration or tissue overgrowth
Clinically available valve prosthesis represent nonviable structure and lack the potential to grow, repair and remodel

Different materials has different properties that need to be adapt into human environment. Click on the related subtopic to know more:
Polymer based scaffolds tissue-engineered heart valve
Natural tissue-engineered heart valve
Mechanical artificial heart valve

Polymer Based Scaffolds Tissue-Engineered Heart Valve

Trileaflet polymeric heart valve

Polymeric heart valve fabricated from polyurethane/polysiliconeurethane

Tissue-Engineered Heart Valve
Tissue-engineered heart valve used polyesters

Thicker, stiffer, and less pliable than the native valves
Heart valve produced from polylactic acid showing slower degrading due to the addition of a methyl group compared to polyglycolic acid
Artificial heart valve produce from polyglycolic acid more susceptible to degradation by hydrolysis which results in a more rapid loss in mechanical properties

Molecular structure of polylactic acid (left) and polyglycolic acid (right)

Tissue-engineered heart valve used thermoplastic polyesters

Molecular structure of polyhydroxyalkanoate

Tissue-engineered heart valve used polyhydroxyoctanoate

The polyhydroxyoctanoate scaffold was still present after 24 weeks and was not sufficiently replaced by neotissue
May enhance host-tissue reactions
An increase in inner diameter and lenght was seen
Due to dilatation of the construct and not growth
Not a confluent endothelium for surface over the leaflet

Tissue-engineered heart valve used poly-4-hydroxybutyrate

Molecular structure of poly-4-hydroxybutyrate

Limited vivo cellular growth
In vitro seeding techniques have resulted in incomplete re-cellularization without evidence of extracellular matrix repair or remodelling
Accelerated calcification and tissue breakdown at various positions on the valve
Ectopic calcification as cellular remnants due to presence of cellular remnants left in the tissue
Subvalvular calcification, inflammatory reaction and an increased thickening of the valve leaflets
Period to expand the cell population, and harvesting diseased cells or cells from geriatric patients may not be an suitable transplantation source
The occurrence of acute valvular malfunction
Mechanical malfunction due to alteration of the poppet or thrombosis of the valve
Alteration in the poppet consist of ball variance, disc variance and wearing of the poppet
Deformities of the poppet have been detected in the aortic and mitral valves
Thrombosis of the valve restricts the poppet movement, thus results in dysfunction
Tissue valve (porcine, bovine, equine) is predictable to last between 10 to 15 years
The other disadvantage is the bioposthetic valve are not as resilient as mechanical valves:
Young patient may need another heart valve replacement to sustain his or her life after 10 to 15 years of first implant

Tissue-engineered heart valve generated from human marrow stromal cells

A typical porcine heart valve

Blood thinners or anticoagulant, Coumadin need to be used by patients
Some patients' bodies intolerant to Coumadin
The valves are too loud and noisy:
A "clicking" noise can be heard as the valve opens-and-closes in the heart
Small annulus sizes and for patients with atrial fibrillation need anticoagulation
Greater severity of hemolysis was found in patients with mechanical ball valve
The occurrence of hemolysis was higher whenever a bileaflet valve was implanted either in aortic and mitral position
In addition to the complexity of the insertion technique of jeopardizing the integrity of a normal right ventricular outflow tract, thereby putting two valves at risk, which could also risk the patients' lives