Method for Reducing Myocardial Infarct by Application of Intravascular Hypothermia

Abstract

Methods and apparatus for preventing myocardial infarction, or lessening the size/severity of an evolving myocardial infarction, by cooling at least the affected area of the myocardium using an intravascular heat exchange catheter. The heat exchange catheter may be inserted into the vasculature (e.g., a vein) and advanced to a position wherein a heat exchanger on the catheter is located in or near the heart (e.g., within the vena cava near the patient's heart). Thereafter, the heat exchange catheter is used to cool the myocardium (or the entire body of the patient) to a temperature that effectively lessens the metabolic rate and/or oxygen consumption of the ischemic myocardial cells or otherwise protects the ischemic myocardium from undergoing irreversible damage or infarction.

What is claimed is: 
     
         1 . A method of limiting or preventing infarction of myocardial tissue in a patient who is suffering from cardiac ischemia, said method comprising the steps of:
 (A) inserting a heat exchange catheter into the vasculature of the patient;   (B) using the heat exchange catheter to lower the patient's body temperature to a hypothermic temperature;   (C) maintaining the hypothermic temperature for a period of time; and   (D) causing or allowing the patient's body temperature to return to normothermia.   
     
     
         2 . A method according to  claim 1  wherein the organ or tissue is cooled to a temperature below 37° C. but not below 30° C. 
     
     
         3 . A method according to  claim 1  wherein the organ or tissue is cooled to a temperature below 37° C. but not below 32° C. 
     
     
         4 . A method as in  claim 1  wherein the organ or tissue is cooled to a temperature below 37° C. but not below 34° C. 
     
     
         5 . A method according to  claim 1  wherein the hypothermic temperature is maintained until the cardiac ischemia has been alleviated. 
     
     
         6 . A method according to  claim 5  wherein the hypothermic temperature is maintained until the cardiac ischemia has been alleviated by one or more ischemia-alleviating treatment selected from; a) administration of anti-ischemic medication; b) performance of angioplasty, stenting, atherectomy or other catheter-based coronary intervention and c) performance of coronary artery bypass or other coronary revascularization surgery. 
     
     
         7 . A method according to  claim 1  wherein the heat exchange catheter is positioned to cool blood flowing through the subject's inferior vena cava. 
     
     
         8 . A method according to  claim 1  wherein the heat exchange catheter is positioned to cool blood flowing through the subject's superior vena cava. 
     
     
         9 . A method according to  claim 1  wherein Step B comprises cooling the entire body of the subject. 
     
     
         10 . A method according to  claim 1  wherein the heat exchange catheter has an elongate catheter shaft and a heat exchange region located on a portion of the catheter shaft that becomes inserted into the patient's vasculature. 
     
     
         11 . A method according to  claim 10  wherein the heat exchange region has a helical configuration. 
     
     
         12 . A method according to  claim 10  wherein the heat exchange region has a bellows-shaped surface. 
     
     
         13 . A method according to  claim 10  wherein the heat exchange region has a right spiral region, a left spiral region and a bellows shaped region located between the right spiral region and left spiral region. 
     
     
         14 . A method according to  claim 10  wherein the heat exchange region comprises a heat exchange balloon through which heat exchange fluid is circulated. 
     
     
         15 . A method according to  claim 14  wherein the heat exchange balloon has a helical configuration. 
     
     
         16 . A method according to  claim 15  wherein the heat exchange balloon comprises a plurality of tubular balloon lobes wound helically about a portion of catheter. 
     
     
         17 . A method according to  claim 1  wherein heat exchange of about 220 Watts occurs during Step B.