Myocardial infarction (Table 5) is caused by abrupt anoxia to a portion of the heart resulting in myocardial tissue necrosis. Anoxia results from conditions that lead to the formation of atherosclerotic plaques. In later stages, atherosclerotic plaques may become disrupted and contribute to thrombus formation. Atherosclerotic plaques and thrombi impair blood flow to large and medium-sized arteries of the heart. History of cardiovascular diseases, diabetes mellitus, and cerebrovascular disease increases the overall risk of perioperative MI.
Table 5. Myocardial Infarction.
Prevention:
Identify at-risk patient
Reduce anxiety
Ensure profound local anesthesia
Use local anesthetic agents containing a vasoconstrictor congruent with the patient’s functional capacity
Signs and symptoms:
Severe substernal chest pain lasting longer than 3 to 5 minutes
Radiates to the arms, neck, shoulders, or jaw
Weakness, dizziness, light-headedness
Nausea and/or vomiting
Dyspnea, tachypnea, or apnea
Pale or ashen skin (especially around the face)
Diaphoresis
Cool, clammy skin
Hypotension
Systolic blood pressure <90 mm Hg
Tachycardia (over 100 beats/minute)
Palpitation
Emergency response:
Place patient in an upright or semi-reclining position
Notify EMS
Administer oxygen
6 L/min by nasal cannula
Encourage patient to chew an adult aspirin, 325 mg, unless otherwise contraindicated
Monitor vital signs
If at any time the patient becomes unresponsive, no normal breathing, and no palpable pulse consider the diagnosis of cardiac arrest
Immediate CPR and defibrillation congruent with current recommendations
Nota bene:
Signs of recovery: pain is subsiding, vital signs returning to baseline values
Signs of deterioration: pain persists, vital signs unstable, altered mentation (loss of consciousness)
Signs and symptoms of MI vary from mild, vague discomfort to cardiogenic shock with an overall mortality rate to greater than 80%
Patient denial may minimize symptoms and elderly and diabetic patients have a higher incidence of silent MI characterized by vague symptoms of shortness of breath, epigastric distress, hypotension, and altered mental state
More than 60 days should elapse after a MI before elective noncardiac procedures, e.g., elective dental care
Recent MI, defined as having occurred within 6 months of noncardiac surgery, is an independent risk factor for perioperative stroke
