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« on: April 20, 2017, 02:40:55 PM »
Myocardial infarction (MI) (ie, heart attack) is the irreversible death (necrosis) of heart muscle secondary to prolonged lack of oxygen supply (ischemia). Approximately 1.5 million cases of MI occur annually in the United States.
Signs and symptoms
Patients with typical MI may have the following symptoms in the days or even weeks 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
Substernal, and often radiates up to the neck, shoulder, and jaw, and down 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 (tachycardic) 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
However, with right ventricular MI or severe left ventricular dysfunction, hypotension and cardiogenic shock can be seen
The respiratory rate may be increased in response to pulmonary congestion or anxiety
Coughing, wheezing, and the production of frothy sputum may occur