They wouldn't be able to open and close correctly, resulting in backflow of blood.
Yes. That is 'the' function of the heart valves or for that matter valves.
the valves close
semilunar valves
You have the atrioventricular valves that are the valves separating each atrium from the ventricles. The right AV valve is the tricuspid valve, while the left AV valve is the bicuspid/mitral valve. There are also two valves that lead from the heart to the pulmonary and aortic arteries. These are the pulmonary and aortic valves. They are both semilunar valves because of their shape.
Plastic valves can be purchased from stores such as Pipestock and Halfords, dependent on what they are to be used for. Other car care stores can provide plastic valves as well.
The mitral and aortic valves may also be affected by deposits of calcium in the heart that occurs with aging. This can lead to thickening and leakage of heart valves. Heart attacks also can damage the mitral valve structures.
The valves of the heart become less pliant over time. Also, calcium deposits may develop on the valves, preventing them from sealing completely. this can result in mitral valve prolopse, mitral regurgitation and ultimately congestive heart failure.
The deposits on the leaflets of valves are called vegetations.
The valves, particularly the exhaust valves, will become damaged quite quickly
oil filled lifters no adjustment
Stuck valves are usually caused by a build-up of deposits.
If multivalvular disease is suspected or involved, different valves may be evaluated during surgery on one of the affected valves.
Normally when there is oil deposits on the spark plugs you need to have some work done on the valves, preferably the valve seals, but should do a complete valve job to make sure everything is at specs.
Evacuated
Sodium is a solid at room temperature and becomes a liquid at 97.5 degrees Celsius. Sodium cooled valves are exhaust valves in a cylinder head of an engine that open to release exhaust gasses that were formed due to combustion of fuel and air inside the cylinders and typically get very hot. The sodium cooled valves and exhaust valves filled with sodium inside, the sodium helps the valves be cooler than if they were just solid.
Premium Leaded Gasoline. If you run unleaded gas the valves will eventually wear out because the lead was a lubricant. The valves would need to be retrofitted to sodium filled or some other type that can survive without the lead.
The heart valves- the bicuspid and tricuspid valves- are there to prevent blood from back-welling into the atria after atrial systole (contraction). Once the atria have filled the ventricles of the heart with blood, the valves close- making the "heartbeat sound." The ventricles can then contract. If these valves didn't exist, then the blood would flow back into the atria, and you'd probably have a colossal heart attack and die. Isn't Biology a cheery subject?!