Heart valve prototype made from cattle tissue

Photomacrograph of a heart valve prototype made from cattle tissue. When a heart valve doesn't open or close properly this can disrupt blood flow or allow blood to leak, leading to heart valve disease. If a valve can't be repaired it may be replaced with either a mechanical or a tissue valve. Unlike with mechanical valves, tissue valves taken from cows, pigs or human donors, usually don't require lifetime anti-coagulant (blood thinner) treatment. Width of image is 4 cm.