Method for pre-stretching implantable biocompatible materials, and materials, and devices produced thereby

A method of pre-stretching pericardial tissue comprising:

• applying a tensioning force of between about 400 grams and about 1000 grams to the sheet of pericardial tissue;
• while applying the tensioning force, maintaining the sheet of pericardial tissue at a temperature of between about 30° C. and about 46° C.;
• and
• maintaining the sheet of pericardial tissue under tension until the elongation rate of the sheet is less than about 10% of an average initial elongation rate, where the average initial elongation rate is the elongation rate over the first hour in which tension is applied.

A method of forming a prosthetic valve, comprising:

• applying a tensioning force of between about 400 grams and about 1000 grams to the sheet of pericardial tissue;
• while applying the tensioning force, maintaining the sheet of pericardial tissue at a temperature of between about 30° C. and about 46° C.;
• maintaining the sheet of pericardial tissue under tension until the elongation rate of the sheet is less than about 10% of an average initial elongation rate, where the average initial elongation rate is the elongation rate over the first hour in which tension is applied;
• and
• attaching at least a portion of the sheet of elongated pericardial tissue to a frame.