Method of laser cutting pericardial tissue for use with an implantable medical device
A method of cutting material for use in an implantable medical device employs a plotted laser cutting system. The laser cutting system is computer controlled and includes a laser combined with a motion system. The laser precisely cuts segments out of source material according to a predetermined pattern as designated by the computer. The segments are used in constructing implantable medical devices. The cutting energy of the laser is selected so that the cut edges of the segments are melted to discourage delamination or fraying, but communication of thermal energy into the segment beyond the edge is minimized to avoid damaging the segment adjacent the edge.
1. A method of creating an implantable medical prosthesis, comprising:
providing a sheet of pericardium, wherein the pericardium has at least two tissue layers;
cutting a segment of tissue out of the sheet of pericardium with a laser beam;
said cutting comprising operating a laser at a power and pulse rate such that said beam welds the layers of the pericardium together along a laser cut edge;
wherein the laser is operated in a pulsed manner, supplying between about 0.005-0.5 joules of laser energy per pulse, with a laser spot size of about 0.002-0.005 inches in diameter, thereby producing a laser cut edge without significantly burning the pericardium adjacent the cut edge.
2. The method of claim 1 , wherein the pericardium tissue comprises equine pericardium.
3. The method of claim 1 , wherein the laser beam power and pulse rate are selected so that there is substantially no discoloration of the pericardium along the cut edge.
4. The method of claim 1 , wherein the prosthesis comprises a heart valve, said cutting comprising cutting a plurality of segments of tissue out of the sheet of pericardium with the laser beam and attaching the cut segments to one another to form the valve.
5. The method of claim 1 , comprising moving the laser beam at a cutting speed of about 1 inch per second and a pulse rate of about 1000 pulses per inch.
6. The method of claim 5 , wherein the laser beam supplies between about 0.005-0.02 joules of laser energy per pulse.
7. The method of claim 1 , wherein the laser beam operates at a wavelength of about 10.6 microns.
8. The method of claim 1 , wherein the laser beam operates at a wavelength of about 2.7-3.0 microns.
9. The method of claim 1 , wherein the laser energy is about 0.0075 joules per pulse and a laser spot diameter of about 0.003 inches.