Myocardial infarction

Myocardial infarction (MI) (ie, heart attack) is the irreversible death (necrosis) of heart muscle secondary to prolonged lack of oxygen supply (ischemia).


Overview

Practice Essentials

Myocardial infarction (MI) (ie, heart attack) is the irreversible death (necrosis) of heart muscle secondary to prolonged lack of oxygen supply (ischemia).

Acute myocardial infarction, reperfusion type. In this case, the infarct is diffusely hemorrhagic. There is a rupture track through the center of this posterior left ventricular transmural infarct.

The mechanism of death was hemopericardium.

Signs and symptoms

Patients with typical MI may have the following prodromal symptoms in the days preceding the event (although typical STEMI may occur suddenly, without warning):
*Fatigue


*Chest discomfort


*Malaise



Typical chest pain in acute MI has the following characteristics:
*

Intense and unremitting for 30-60 minutes

Retrosternal and often radiates up to the neck, shoulder, and jaw and down to the ulnar aspect of the left arm

Usually described as a substernal pressure sensation that also may be characterized as squeezing,

* aching, burning, or even sharp.


In some patients, the symptom is epigastric, with a feeling of indigestion or of fullness and gas



The patient’s vital signs may demonstrate the following in MI:


The patient’s heart rate is often increased secondary to a high sympathoadrenal discharge.


The pulse may be irregular because of ventricular ectopy, an accelerated idioventricular rhythm, ventricular tachycardia, atrial fibrillation or flutter, or other supraventricular arrhythmias; bradyarrhythmias may be present

In general, the patient's blood pressure is initially elevated because of peripheral arterial vasoconstriction resulting from an adrenergic response to pain and ventricular dysfunction.

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