Cryoablation catheter assembly, cryoablation system and method
A cryoablation catheter assembly is described. The assembly comprises (a) an inlet for receiving an input flow of refrigerant fluid, (b) a cryo-applicator, (c) a flow splitter configured to split the input flow into a therapeutic flow portion and a precooling flow portion, and (d) a precooling arrangement configured to precool the therapeutic flow portion and guide the precooled therapeutic flow portion towards the cryo-applicator, wherein the precooling arrangement comprises a heat exchanger configured to apply an adjustable precooling power from the precooling flow portion to the therapeutic flow portion. Furthermore, a cryoablation system and a method are described.
1 . A cryoablation catheter assembly, the assembly comprising:
an inlet for receiving an input flow of refrigerant fluid,
a cryo-applicator,
a flow splitter configured to split the input flow into a therapeutic flow portion and a precooling flow portion,
a precooling arrangement configured to precool the therapeutic flow portion and guide the precooled therapeutic flow portion towards the cryo-applicator,
wherein the precooling arrangement comprises a heat exchanger configured to apply an adjustable precooling power from the precooling flow portion to the therapeutic flow portion,
wherein the heat exchanger comprises a boiling chamber, a conduit configured to guide the precooling flow portion from the flow splitter to the boiling chamber, and a heat transfer structure in thermal contact with the boiling chamber and configured to guide the therapeutic flow portion,
wherein the conduit comprises a microtube having a flow impedance selected to maintain a ratio between the precooling flow portion and the input flow within a predetermined range, and
a closing structure is arranged between the conduit and the boiling chamber, the closing structure being configured to adjust a flow cross-section in dependency of temperature.
2 . The assembly according to claim 1 , wherein the microtube has a cross-sectional area of 0.1 mm 2 or less.
3 . The assembly according to claim 1 , wherein the microtube has a length of at least 5 mm.
4 . The assembly according to claim 2 , wherein the microtube has an inner diameter of 90 μm and a length of 40 mm.
5 . The assembly according to claim 1 , wherein the precooling arrangement comprises a temperature adjustment device configured to adjust the temperature of the precooling flow portion within the conduit.
6 . The assembly according to claim 5 , wherein the temperature adjustment device comprises an adjustable electric heating unit configured to heat the conduit.
7 . The assembly according to claim 5 , wherein the temperature adjustment device comprises an adjustable heating and cooling unit configured to selectively heat and cool the conduit.
8 . The assembly according to claim 5 , further comprising at least one temperature sensor arranged and configured to provide a temperature signal indicative of the temperature of the therapeutic flow portion, wherein the temperature adjustment device is configured to adjust the temperature of the precooling flow portion within the conduit in dependency on the temperature signal.
9 . The assembly according to claim 8 , wherein the at least one temperature sensor comprises a first temperature sensor arranged in or on the heat exchanger and adapted to sense a temperature of the precooled therapeutic flow portion leaving the heat exchanger, and/or wherein the at least one temperature sensor comprises a second temperature sensor arranged and adapted to sense a temperature of the precooling flow portion.
10 . The assembly according to claim 8 , wherein the at least one temperature sensor comprises a third temperature sensor arranged and adapted to sense a temperature of the therapeutic flow portion within the cryo-applicator.
11 . The assembly according to claim 8 , wherein the at least one temperature sensor comprises a fourth temperature sensor arranged and adapted to sense a temperature of the therapeutic flow portion leaving the cryo-applicator.
12 . The assembly according to claim 1 , wherein the heat transfer structure has an elongate shape and extends through the boiling chamber.
13 . The assembly according to claim 1 , wherein the heat exchanger is configured as a counter flow heat exchanger or as a parallel flow heat exchanger.
14 . The assembly according to claim 1 , further comprising a handle, wherein the precooling arrangement is arranged within the handle.
15 . A cryoablation system, the system comprising:
a cryoablation catheter assembly, said cryoablation catheter assembly comprising:
an inlet for receiving an input flow of refrigerant fluid, a cryo-applicator,
a flow splitter configured to split the input flow into a therapeutic flow portion and a precooling flow portion,
a precooling arrangement configured to precool the therapeutic flow portion and guide the precooled therapeutic flow portion towards the cryo-applicator,
wherein the precooling arrangement comprises a heat exchanger configured to apply an adjustable precooling power from the precooling flow portion to the therapeutic flow portion,
wherein the heat exchanger comprises a boiling chamber, a conduit configured to guide the precooling flow portion from the flow splitter to the boiling chamber, and a heat transfer structure in thermal contact with the boiling chamber and configured to guide the therapeutic flow portion, and
wherein the conduit comprises a microtube having a flow impedance selected to maintain a ratio between the precooling flow portion and the input flow within a predetermined range,
a console configured to supply a flow of refrigerant fluid to the inlet of the cryoablation catheter assembly,
wherein the console comprises a preconditioning unit configured to adjust a specific enthalpy of the refrigerant fluid to a predetermined value, and
a closing structure is arranged between the conduit and the boiling chamber, the closing structure being configured to adjust a flow cross-section in dependency of temperature.
16 . The system according to claim 15 , further comprising a controller configured to determine the predetermined value in dependency on at least one measured temperature.