1. A catheter (20) made with the possibility of irrigation ablation of tissue (40) with an open loop, said catheter comprising a distal tip (22), comprising: an ablation device (15) capable of ablation of tissue； - an irrigation hole ( 21)； and - an ultrasonic transducer (5), configured to transmit and / or receive ultrasonic waves； wherein the ultrasonic transducer is located behind or inside the irrigation hole of the catheter to allow irrigation fluid to flow out of the irrigation hole and to allow transmission and / or reception of ultrasonic waves through an irrigation hole. 2. A catheter according to claim 1, in which the distal tip (22) comprises a plurality of irrigation holes (21 ', 21 "). 3. A catheter according to claim 1, in which the distal tip (22) comprises a plurality of ultrasonic transducers (5', 5" ).four. The catheter according to claim 3, in which at least a subset of the plurality of ultrasonic transducers (5 ', 5 ") is individually addressed. 5. The catheter according to claim 3, in which the number of ultrasonic transducers (5', 5") is equal to or less than the number of irrigation holes (21 ', 21 "). 6. A catheter according to claim 2 or 3, in which each ultrasound transducer (5', 5") is located behind or inside the corresponding irrigation hole (21 ', 21 "). 7. The catheter according to claim 1, in which the diameter of the irrigation hole (21) is larger than the diameter of the ultrasonic transducer (5). er according to claim 3, in which many ultrasonic transducers (5 ', 5 ") are provided with a common material (60) of the ultrasonic substrate. The catheter according to claim 2, in which the ablation device (15) determines a region on the distal1. Катетер (20), выполненный с возможностью ирригационной абляции ткани (40) с незамкнутым контуром, причем упомянутый катетер содержит дистальный наконечник (22), содержащий:- устройство (15) для абляции, выполненное с возможностью абляции ткани；- ирригационное отверстие (21)； и- ультразвуковой пре
