Cryotherapy Methods for Treating Vessel Dissections and Side Branch Occlusion

Abstract

The present invention provides cryotherapy treatment of dissections in a blood vessel of a patient. The present invention further provides cryotherapy treatment of side branch occlusion in a bifurcated blood vessel. One method for treating potential or existing dissections in a blood vessel comprises cooling the blood vessel to a temperature and for a time sufficient to remodel the blood vessel such that dissections of the blood vessel are reduced. Another method for treating side branch occlusion in a bifurcated blood vessel, the bifurcated blood vessel having a side branch and a main branch, the main branch having plaque disposed thereon, comprises cooling an inner surface of the main branch to a temperature and for a time sufficient to inhibit plaque shift from the main branch into the side branch.

1 . A cryotherapy delivery system comprising:
 a cryotherapy catheter comprising a catheter body, the catheter configured to deliver a cryogenic fluid from a proximal end of the catheter body toward a distal end of the catheter body; and   a controller configured to:
 control a rate of flow of the cryogenic fluid, in response to a measured temperature received via a sensor, to cool an inner surface of a main branch of a bifurcated blood vessel having plaque disposed thereon to a temperature and for a time sufficient to inhibit plaque shift from the main branch into a side branch of the bifurcated blood vessel, 
 wherein the cooling time is in a range from about 1 second to less than about 20 seconds, and wherein the cooling temperature of the inner surface of the main branch is in a range from about −3° C. to about −15° C. 
   
     
     
         2 . The system of  claim 1 , wherein the main branch is an artery. 
     
     
         3 . The system of  claim 1 , wherein the plaque comprises a combination of calcium, fat, and lipids. 
     
     
         4 . The system of  claim 1 , wherein the side branch is subject to occlusion by plaque shift from the main branch into the side branch as a result of treatment of plaque in the main branch. 
     
     
         5 . The system of  claim 4 , wherein the treatment of plaque in the main branch comprises balloon angioplasty. 
     
     
         6 . The system of  claim 5 , wherein the cooling step is performed before, during, and/or after balloon angioplasty. 
     
     
         7 . The system of  claim 6 , wherein the side branch is at least partially stenosed. 
     
     
         8 . The system of  claim 7 , wherein the treatment of stenosis in the side branch comprises balloon angioplasty. 
     
     
         9 . The system of  claim 8 , wherein the main branch and the side branch are treated simultaneously or sequentially. 
     
     
         10 . The system of  claim 1 , wherein the cooling step alters mechanical properties of the plaque so that plaque shift from the main branch to the side branch is inhibited. 
     
     
         11 . The system of  claim 10 , wherein the cooling step solidifies the plaque so that it is less amorphous. 
     
     
         12 . The system of  claim 11 , wherein the plaque solidification is enhanced by the formation of a temporary ice cap on an orifice of the side branch. 
     
     
         13 . A cryotherapy delivery system comprising:
 a cryotherapy catheter comprising a catheter body, the catheter configured to deliver a cryogenic fluid from a proximal end of the catheter body toward a distal end of the catheter body; and   a controller configured to control a rate of flow of the cryogenic fluid, in response to a measured temperature received via a sensor, to cool a blood vessel lumen defined by a blood vessel wall, with a balloon, to a temperature and for a time sufficient to remodel the blood vessel such that an existing dissection of the blood vessel wall is reduced.   
     
     
         14 . The system of  claim 13 , wherein cooling the vessel lumen tacks or re-attaches existing vessel dissections into the blood vessel wall. 
     
     
         15 . A cryotherapy delivery system comprising:
 a cryotherapy catheter comprising a catheter body, the catheter configured to deliver a cryogenic fluid from a proximal end of the catheter body toward a distal end of the catheter body; and   a controller configured to control a rate of flow of the cryogenic fluid, in response to a measured temperature received via a sensor, to cool an inner surface of a blood vessel having an existing dissection with the balloon to a temperature and for a time sufficient to tack or re-attach a flap of tissue of the dissection to a blood vessel wall of the blood vessel.   
     
     
         16 . The system of  claim 15 , wherein the cooling time is in a range from about 10 seconds to about 60 seconds, and wherein the cooling temperature of the inner surface of the blood vessel is in a range from about −3° C. to about −15° C. 
     
     
         17 . The system of  claim 15 , wherein the blood vessel is an artery. 
     
     
         18 . The system of  claim 15 , wherein the dissection comprises flaps, residual plaque, or pieces of tissue resulting from fissuring or tearing of the blood vessel wall or plaque thereon. 
     
     
         19 . The system of  claim 15 , wherein the dissection at least partially blocks the blood vessel. 
     
     
         20 . The system of  claim 15 , wherein the dissection limits blood flow.