Disclosed is a completely implantable system that can detect the occurrence of a myocardial infarction, i.e., a heart attack, and automatically inject a thrombolytic and/or anti-thrombogenic agent into the bloodstream to promptly dissolve the thrombus that caused the myocardial infarction and prevent the formation of additional thrombi. It is well known that a myocardial infarction can be detected from a patient's electrocardiogram by noting an ST segment voltage deviation. Upon detection of a myocardial infarction, an ST segment deviation electronic detection circuit within the implanted device can produce an output signal that can cause a thrombolytic and/or anti-thrombogenic agent contained within an implanted, pressurized reservoir to immediately and automatically release medications into the patient's bloodstream. A patient warning system is also provided by an audio alarm or an electrical tickle within the human body indicating that a myocardial infarction has been detected. An externally located part of the system, in the form of a patient operated initiator, can be used to trigger the release of medication as soon as a first sign of a stroke has been detected in order to prevent damage to brain tissue that would be caused by that stroke. Thus the system can be used to prevent trissue damage from either a myocardial infarction or a stroke. The implanted system can also send a radio message to an externally located receiver that automatically dials an emergency rescue team to take the patient to a hospital for continuing treatment of a myocardial infarction or a stroke.