Methods and systems for treating ischemia

Abstract

Methods for treating total and partial occlusions employ a perfusion conduit which is penetrated through the occlusive material. Oxygenated blood or other medium is then perfused through the conduit in a controlled manner, preferably at a controlled pressure below the arterial pressure, to maintain oxygenation and relieve ischemia in tissue distal to the occlusion. In another aspect, interventional devices, such as stents or balloon catheters, are passed through the perfusion catheter to remove obstructions. Optionally, the occlusion may be treated while perfusion is maintained, typically by introducing a thrombolytic or other agent into the occlusive material using the perfusion conduit or by employing mechanical means to remove the obstruction. Such methods are particularly suitable for treating acute stroke to prevent damage to the cerebral tissue.

What is claimed is:  
     
         1 . A method of treating an ischemic bed downstream of an obstruction in a patient's cerebral arterial vasculature, comprising the steps of: 
 introducing a catheter into a patient, the catheter having a distal portion, a distal end and a lumen having at least one outlet;    advancing the catheter to an obstruction in an artery in the patient's cerebral vasculature;    passing the distal end of the catheter through the obstruction;    supplying an oxygenated medium downstream of the obstruction; and maintaining the pressure at the location downstream of the obstruction at a pressure lower than normal for a period of time so that the ischemic bed is not exposed to full arterial pressure.    
     
     
         2 . The method of  claim 1 , wherein: 
 the introducing step is carried out with the catheter having first means for sensing pressure at a position along the distal portion of the catheter;    the method further comprising the step of measuring the arterial pressure with the first pressure sensing means; and    the maintaining step being carried out by maintaining a selected pressure measured by the first pressure sensing means.    
     
     
         3 . The method of  claim 2 , further comprising: 
 perfusing the oxygenated medium through the lumen in the catheter at a rate to maintain the selected pressure.    
     
     
         4 . The method of  claim 2 , wherein: 
 the introducing step is carried out with the catheter having second means for sensing pressure, the second pressure sensing means being positioned proximal of the first pressure sensing means.    
     
     
         5 . The method of  claim 1 , wherein: 
 the passing step is carried out so that the catheter and obstruction maintain occlusion of the artery.    
     
     
         6 . The method of  claim 1 , further comprising the step of: 
 providing an expandable member on the catheter, the expandable member being expandable from a collapsed shape to an expanded shape;    expanding the expandable member at a position near or at the obstruction to occlude the artery to prevent the ischemic bed downstream of the occlusion to be exposed to full arterial pressure.    
     
     
         7 . The method of  claim 1 , wherein: 
 the perfusing step is carried out with the period of time being at least 5 minutes.    
     
     
         8 . The method of  claim 1 , wherein: 
 the perfusing step is carried out with the period of time being at least 2 hours.    
     
     
         9 . The method of  claim 1 , wherein: 
 the perfusing step is carried out with the period of time being at least 2 days.    
     
     
         10 . The method of  claim 1 , wherein: 
 the introducing step is carried out with the catheter having a maximum outer dimension of no more than 3.2 mm at a distal portion of the catheter, the distal portion extending for at least 10 cm from the distal end.    
     
     
         11 . The method of  claim 1 , further comprising: 
 advancing an obstruction removal device to the obstruction during the supplying step; and    removing the obstruction with the obstruction removal    
     
     
         12 . The method of  claim 11 , wherein: 
 the removing step is carried out with the obstruction removal device being a device selected from the group consisting of a mechanical disruption element, an RF electrode, an ultrasound transducer and a laser.    
     
     
         13 . The method of  claim 11 , wherein: 
 the obstruction removal device passes over the catheter and forms a lumen in a space between the obstruction removal device and the catheter.    
     
     
         14 . The method of  claim 12 , wherein: 
 the lumen is coupled to a source of liquid which is to be delivered to the obstruction.    
     
     
         15 . A method of accessing the cerebral vasculature, comprising the steps of: 
 providing a catheter having an expandable sidewall;    introducing the catheter into the cerebral vasculature in a collapsed position;    advancing the catheter to a site in the cerebral vasculature; and    expanding the sidewall to an expanded position.    
     
     
         16 . The method of  claim 14 , wherein the providing step is carried out with the catheter including a lumen having a cross-sectional area of at least 0.45 mm 2  along a length of 5 cm from a distal end of the lumen.  
     
     
         17 . The method of  claim 14 , wherein the providing step is carried out with the catheter having a y-arm connector coupled to the lumen and a hemostasis valve for receiving another catheter in the lumen.  
     
     
         18 . The method of  claim 14 , further comprising the step of: 
 advancing the catheter through an obstruction in the cerebral vasculature; and    infusing an oxygenated medium distal to the obstruction through a lumen in the catheter.    
     
     
         19 . The method of  claim 14 , wherein the expanding step is carried out with an outer dimension of the sidewall expanding at least 25% along a portion of the sidewall.  
     
     
         20 . The method of  claim 14 , further comprising the step of: 
 advancing another catheter through a lumen in the catheter.