Nature of the pain in Heart Attack

The pain of Acute Myocardial Infarction is variable in intensity: in most patients it is severe and in some instances intolerable. The pain is prolonged, usually lasting for more than 30 minutes and frequently for a number of hours.
The discomfort is described as constricting, crushing, oppressing or compressing; often the patient complains of a sensation of a heavy weight or a squeezing in the chest.
Although the discomfort is typically described as choking, viselike or heavy pain, it may also be characterized as a stabbing, knifelike, boring, or burning, spreading frequently to both sides of anterior chest, with predilection for the left side.

Often the pain radiates down the ulnar aspect of the arm, producing a tingling sensation in the left wrist, hand, and fingers.
Some patients note only a dull ache or numbness of the wrist in association with severe substernal or precordial discomfort.
In some instances the pain of Acute Myocardial Infarction may begin in the epigastrum and stimulate a variety of abdominal disorders, a fact that often causes MI to be misdiagnosed as "indigestion".
In other patients the discomfort of Acute Myocardial Infarction radiates to the shoulders, upper extremities, neck, jaw, and interscapular region, again usually favoring the left side.
In patients with pre-existing angina pectoris, the pain of infarction usually resembles that of angina with respect to location.
However, it is generally much more severe, lasts longer, and is not relieved by rest and nitroglycerin.

In some patients, especially elderly, Acute Myocardial Infarction (Heart Attack) is manifested clinically not by chest pain but rather by symptoms of acute left ventricular failure and chest tightness or by marked weakness or frank syncope.
These symptoms may be accompanied by diaphoresis, nausea, and vomiting.
The pain of Acute Myocardial Infarction may have disappeared by the time the physician first encounters the patient (or the patient reaches the hospital), or it may persist for many hours.
Opiates - in particular morphine - usually relieve the pain.
Both angina pectoris and the pain of Acute Myocardial Infarction are thought to arise from nerve endings in ischemic or injured, but not necrotic, myocardium.

Thus, in MI, stimulation of nerve fibers in an ischemic area of myocardium surrounding the necrotic central area of infarction probably gives rise of the pain.
Pain often disappears suddenly and completely when blood flow to the infarct territory is restored. In patients in whom reocclusion occurs after thrombolysis, pain recurs if the initial reperfusion has left viable myocardium.
Thus, what has previously been thought of as the "pain of infarction", sometimes lasting for many hours, probably represents pain caused by ongoing ischemia.
The recognition that pain implies ischemia and not infarction heightness the importance of seeking ways to relieve the ischemia, for which pain is a marker.
This finding suggests that the clinician should not be complacent about ongoing cardiac pain under any circumstances.

Updated: January, 27 2010 08:42:51

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