The invention relates to medicine, namely to products of medicinal purpose, and is designed for use in cardiosurgery during operations, directed cessation atrial fibrillation.To pistacea utility model is creation of device, which allows position clamp - ablyator without risk of perforation structures heart, arranged on the path of carrying out its lower branches.Purpose of the achieved by use of silicon tube as device for positioning clamp - ablyatora.Before making maneuver positioning clamp - ablyatora around left atrium lower its branch is inserted in the tubular conductor, preliminarily arranged behind the left atrium in area of left or right pulmonary veins. So, tubular conductor becomes extension of lower branches clamping - ablyatora. Result is complete elimination of from process positioning contact end branches clamping - ablyatora and heart tissue. Result is elimination of risk of perforation heart lower branches clamping - ablyatora.Application of the tubular guide at carrying out operations of radio-frequency fragmentation of left atrium by means of a clamp - ablyatora enables to decrease the risk of heavy intraoperative complications, to increase speed of and to improve the result of this type of operations.