Cardioprotection by organs in stress or distress

Several studies now suggest that the myocardium can be protected by forms of stress other than myocardial ischemia. These include stimuli which stress the heart but do not lead to ischemia (stretch ventricular pacing) and stimuli which cause distress (ischemia) in organs other than the heart. Since ischemia in remote organs such as kidney (14), brains (15), skeletal muscle (16) and liver (17) can also precondition these organs, it is clear that several forms of stress or distress are capable of triggering processes which protect the organ subjected to the stimulus as well as other organs. It would thus appear that ischemic myocardial preconditioning may be merely one aspect of a general phenomenon that results in organ protection. Future investigations should therefore aim to unravel the mechanisms leading to organ protection which may then be pharmacologically exploited. It is also important to keep in mind, however, that not all forms of (di)stress (myocardial hibernation (4), smoking (18) result in myocardial protection. Finally, these newly recognized protective stimuli may, in addition to problems with infarct size determination in patients as outlined elsewhere (19, 20), be confounding factors in finding definitive proof for the occurrence of ischemic myocardial preconditioning in man.