Inhibition of platelet activation, aggregation and/or adhesion by hypothermia
View Patent ↗A method for treating acute coronary syndromes (i.e., unstable angina or non-Q-wave MI) or transient ischemic attacks in a human or animal patient by placing a heat exchange apparatus in the patient=s vasculature and using that heat exchange apparatus to cool the patient to a temperature (e.g. 30-36_C) at which platelet inhibition (i.e., inhibition of platelet activation and/or aggregation and/or adhesion) occurs. Anti-shivering drugs or anesthesia may be administered to patients whose body temperature is cooled below that patient=s shivering threshold (typically approximately 35.5 C). If it is determined that platelet inhibition is no longer desirable, such as when the patient is about to undergo a surgical or interventional procedure wherein bleeding could be problematic, the hypothermia-induced platelet inhibition may be rapidly reversed by using the intravascular heat exchange apparatus to re-warm the patient=s body to normothermia or near normothermia.
1. A method for inducing and subsequently reversing platelet inhibition in a human or veterinary patient prior to the patient undergoing surgery or another invasive medical procedure known to cause bleeding, said method comprising the steps of:
a) placing an intravascular heat exchange apparatus having a heat exchange surface within the vasculature of the patient; and,
b) using the intravascular heat exchange apparatus to cool at least a portion of the patient's body to a temperature at which platelet inhibition occurs for a reversible platelet inhibition time period;
c) using the intravascular heat exchange apparatus to warm at least a portion of the patient's body to a temperature at which the platelet inhibition is reversed and no longer occurs; and, thereafter,
d) performing, on the patient, a surgery or another invasive medical procedure known to cause bleeding.
2. A method according to claim 1 wherein diagnostic testing is performed during the reversible platelet inhibition time period.
3. A method as in claim 1 wherein the reversible platelet inhibition time period is less than 4 hours.
4. A method according to claim 1 wherein at least the portion of the patient's body in which platelet inhibition is desired is cooled to a temperature below approximately 36° C. but greater than approximately 30° C.
5. A method according to claim 4 wherein the temperature is between approximately 32° C. and approximately 34° C.
6. A method according to claim 1 wherein the intravascular heat exchange device is an elongate flexible catheter that comprises a heat exchanger.
7. A method according to claim 6 wherein the heat exchanger of the catheter comprises less than the full length of the catheter that becomes inserted in the patients vasculature.
8. A method according to claim 1 wherein the heat exchange apparatus is placed in the patient's venous vasculature.
9. A method according to claim 8 wherein the heat exchange apparatus is placed in the patient's vena cava.
10. A method according to claim 9 wherein the heat exchange apparatus is placed in the patient's inferior vena cava.
11. A method according to claim 9 wherein the heat exchange apparatus is placed in the patient's superior vena cava.
12. A method according to claim 1 wherein at least one surface projection is formed on the heat exchanger to increase the effective heat exchange surface area of the heat exchanger.
13. A method according to claim 12 wherein the at least one surface projection comprises a fin.
14. A method according to claim 13 wherein said fin comprises a raised area on at least a blood-contacting surface of the heat exchanger.
15. A method according to claim 13 wherein said fin comprises a ridge.
16. A method according to claim 13 wherein said fin comprises a bulge.
17. A method according to claim 1 further comprising the step of:
removing the heat exchange apparatus from the patient's body.
18. A method according to claim 1 wherein the method is carried out in a patient who has been diagnosed with unstable angina.
19. A method according to claim 1 wherein the method is carried out in a patient who has been diagnosed with non-Q wave myocardial infarction.