Patent ID: 8882761

Claim:
A method of ablating a biological tissue surrounded by blood, comprising: providing an electrode having a first portion enclosed within an elongated housing of a catheter and a second portion exposed outside the catheter; the first portion being of a shape having a first surface area substantially larger than a second surface area of the second portion and being in fluid communication with a coolant for exchanging heat therewith; the second portion being of a shape having a protruding surface that when disposed to ablate a biological tissue is substantially covered by and in contact with the biological tissue while leaving a minimum surface area uncovered by the biological tissue and exposed to blood, the minimum surface area being less than 35% of the total second surface area of the second portion; disposing the second portion of the electrode against the biological tissue by introducing the catheter percutaneously into a heart chamber; cooling the electrode with the coolant at a rate which is an order of magnitude smaller than 30 ml/minute while minimizing blood coagulation; and supplying a predetermined amount of RF energy to create a lesion of a predetermined size to the biological tissue surrounded by blood.