Controlled balloon deployment

Abstract

The methods and devices disclosed herein promote temporal control of balloon inflation patterns. The devices include a covering for a portion of the balloon that compresses the balloon portion during the inflation process. This enables the distal portion of a balloon to be inflated prior to the proximal portion of a balloon, creating a tapered shape at lower inflation pressures. This is especially useful during transvascular implantation procedures, as it prevents dislodgement of an implant mounted on the balloon. As inflation continues, pressure exerted on the balloon by the covering is overcome such that the proximal region of the balloon inflates, forming a shape with generally straighter sides than the tapered shape, thereby expanding the cardiovascular device.

What is claimed is: 
     
         1 . A controlled balloon deployment device including:
 a delivery catheter comprising a distal portion, the distal portion comprising a distal end;   a balloon configured to move through the delivery catheter and to be deployed beyond the distal end of the delivery catheter;   a cardiovascular device positioned around at least a portion of the balloon; and   a covering extending through the distal portion of the delivery catheter and over at least a portion of the balloon,   wherein a portion of the covering is positioned between an outer surface of the balloon and an inner surface of the cardiovascular device when the balloon is deployed beyond the distal end of the delivery catheter.   
     
     
         2 . The controlled balloon deployment device of  claim 1 , wherein the covering is an expandable sheath. 
     
     
         3 . The controlled balloon deployment device of  claim 2 , wherein the sheath comprises a polymer material. 
     
     
         4 . The controlled balloon deployment device of  claim 1 , wherein the covering has an increased opacity compared to the balloon. 
     
     
         5 . The controlled balloon deployment device of  claim 1 , wherein the cardiovascular device is a prosthetic heart valve, wherein inflation of the balloon causes the prosthetic heart valve to expand. 
     
     
         6 . The controlled balloon deployment device of  claim 1 , wherein the cardiovascular device is a stent. 
     
     
         7 . The controlled balloon deployment device of  claim 1 , wherein the covering extends through the distal portion of the delivery catheter and over a proximal portion of the balloon. 
     
     
         8 . The controlled balloon deployment device of  claim 1 , wherein in a partially inflated state, compressive forces provided on the portion of the balloon by the cover causes a distal region of the balloon to inflate before a proximal region of the balloon forming a tapered shape with an enlarged distal region,
 wherein in a fully inflated state, the balloon overcomes the compressive forces provided on the portion of the balloon by the cover such that the balloon has a shape with generally straighter sides than the tapered shape.   
     
     
         9 . The controlled balloon deployment device of  claim 1 , wherein in a partially inflated state, the balloon has a tapered shape,
 wherein in the tapered partially inflated state of the distal region of the balloon is larger than the proximal region of the balloon,   wherein in a fully inflated state the balloon has a shape with generally straighter sides than the tapered shape.   
     
     
         10 . The controlled balloon deployment device of  claim 9 , wherein the tapered shape extends under the cardiovascular device, wherein the cardiovascular device does not extend to a distal end of the balloon. 
     
     
         11 . The controlled deployment device of  claim 1 , further including:
 a balloon catheter configured to move through the delivery catheter, wherein the balloon is provided on the balloon catheter and configured to move through a distal end of the delivery catheter with the balloon catheter, a distal end of the balloon catheter is capped with a nosecone that abutting a distal end of the balloon.   
     
     
         12 . A method of controlling expansion of a balloon, the method comprising:
 flowing a fluid into the balloon;   compressing a proximal region of the balloon by exerting pressure on the proximal region of the balloon with a covering and an implantable cardiovascular device, thereby inflating a distal region of the balloon before the proximal region of the balloon to form a tapering shape with an enlarged distal region,   wherein a portion of the covering is positioned between an outer surface of the balloon and an inner surface of the cardiovascular device.   
     
     
         13 . The method of  claim 12 , further comprising:
 continuing to flow fluid into the balloon and overcoming the pressure on the proximal region of the balloon.   
     
     
         14 . The method of  claim 12 , further comprising:
 inflating the balloon into a shape with generally straighter sides than the tapered shape.   
     
     
         15 . The method of  claims 13 , wherein continuing the flow of fluid comprises progressively transitioning from flowing fluid into the distal region to flowing fluid into the proximal region. 
     
     
         16 . The method of  claim 12 , wherein flowing fluid into the balloon causes a rise in an inflation pressure,
 wherein inflating a distal region of the balloon before the proximal region of the balloon occurs at a first inflation pressure, and   wherein inflating the balloon into a shape with generally straighter sides than the tapered shape occurs at a second inflation pressure that is higher than the first inflation pressure.   
     
     
         17 . The method of  claim 16 , wherein the enlarged distal region of the balloon has a distal diameter that is larger than a proximal diameter of the proximal region of the balloon when the inflation pressure is from 0.5 to 4 atmospheres. 
     
     
         18 . The method of  claim 17 , wherein a ratio of the proximal diameter of the balloon to the distal diameter of the balloon is 0.85 or greater at inflation pressures over 2.5 atmospheres. 
     
     
         19 . The method of  claim 12 , wherein the cover includes a taper at its distal end, the taper flaring outwards from a longitudinal axis of the cover and extending under the cardiovascular device. 
     
     
         20 . The method of  claim 12 , further comprising:
 mounting the implantable cardiovascular device in a crimped configuration on the balloon before flowing the fluid into the balloon.