about 13 mm sec 0 5 in sec in a clinical trial on a human heart the laser was set to provide about 35 mj mm 2 at a rate of about 30 hz with a feed rate of about 0 95 mm sec i e advancing the fiber at approximately 1 25 thousandths if an inch per pulse typically a healthy heart has a wall thickness of 10 15 mm a diseased heart may be as thick as 40 mm measured from the outer surface of the epicardium to the inner wall of the myocardium at a minimum the laser ablation device 10 and control assembly should be capable of advancing the optical fiber 18 through a stroke having a length at least as great as the thickness of the heart being treated alternately it is possible to create channels in the myocardium from within the heart by introducing the laser fiber into the patient 39 s vasculature or through an opposing heart wall and directing the fiber tip to the desired location see for example u s pat no 5 389 096 to aita et al in this approach once the fiber is properly placed controlled advancement of the fiber can be achieved as described above however with this approach the fiber preferably will not penetrate the epicardium referring now to fig6 8 laser fiber 18 and fiber advancing mechanism 12 fig1 can also be used to perform laser angioplasty during the laser angioplasty procedure the optical fiber 18 is inserted into a blood vessel 62 such that the distal end 60 of the optical fiber 18 is positioned adjacent a plaque obstruction 64 fig6 as is.