Durability of prosthetic heart valves

Area of Science:

• Biomedical Engineering
• Cardiovascular Research
• Materials Science

Background:

• Clinical heart valve prostheses undergo significant stress, necessitating robust fatigue testing.
• Understanding the correlation between accelerated in vitro testing and in vivo performance is crucial for device development.

Purpose of the Study:

• To evaluate the accelerated fatigue performance of various clinical heart valves.
• To compare in vitro fatigue results with in vivo clinical durability data.

Main Methods:

• Mechanical heart valves (both non-biological and tissue) were subjected to accelerated fatigue testing at 33-35 Hz and 37°C.
• Testing utilized physiological flow ranges and a closure pressure difference of 100 ± 25 mm Hg.
• Durability was assessed by the number of cycles to major fatigue failure.

Main Results:

• Significant fatigue was observed in mechanical valves, with cycle counts ranging from 60 to 973 million.
• The Lillehei-Kaster valve showed no discernible wear after 762 million cycles.
• In vitro wear patterns and sites accurately predicted in vivo component wear and fatigue locations for mechanical valves.

Conclusions:

• In vitro fatigue testing accurately predicts the in vivo performance and durability of mechanical heart valves.
• A significant discrepancy exists between in vitro and clinical data for tissue heart valves.
• Caution is advised regarding the extrapolation of in vitro results to predict the clinical durability of tissue valves.