What is it?
Myocardial infarction (MI) (ie, a heart attack) is the irreversible death (necrosis) of the secondary heart muscle due to prolonged lack of oxygen supply (ischemia).
Signs and symptoms
Patients with MI can have the following symptoms in the days before the event:
- Chest discomfort
- Intense and constant chest pain for 30-60 minutes. It is usually described as a feeling of substernal pressure that can also be characterized as compression, pain, burning, or even acute.
In some patients, the symptom is epigastric, with a sensation of indigestion or fullness and gas.
The patient’s vital signs can demonstrate the following:
The patient’s heart rate often increases with a sympathetic adrenal surge. The pulse may be irregular due to ventricular ectopia, an accelerated idioventricular rhythm, ventricular tachycardia, fibrillation or atrial flutter or other supraventricular arrhythmias; Bradyarrhythmias may be present.
In general, the patient’s blood pressure is initially elevated due to peripheral arterial vasoconstriction as a result of an adrenergic response to ventricular dysfunction and pain.
However, with a Myocardial Infarction in the right ventricle or severe left ventricular dysfunction, it would generate hypotension. The respiratory rate may increase in response to pulmonary congestion or anxiety. Coughing, wheezing, can produce foamy sputum.
The medical check-up is essential to avoid a possible myocardial infarction, by means of:
- The laboratory studies.
Laboratory tests used in the diagnosis of myocardial infarction include the following:
The ECG is the most important tool in the initial evaluation and triage of patients in whom an acute coronary syndrome (ACS) is suspected, such as myocardial infarction. Confirmation of the diagnosis is approximately 80% of the cases.
For individuals with high probability or confirmed acute myocardial infarction, coronary angiography can be used to definitively diagnose or rule out coronary artery disease.
For patients with chest pain, prehospital care includes the following:
- Intravenous access, supplemental oxygen, pulse oximetry.
- The immediate administration of aspirin.
- Nitroglycerin for active chest pain, sublingually or by sprinkling.
- Telemetry and prehospital ECG, if available.
Emergency service and hospital care
Initial stabilization of patients with suspected myocardial infarction and ongoing chest pain should include administration of sublingual nitroglycerin if patients have no contraindications to it.