1-26
1-26. ACUTE MYOCARDIAL INFARCTION
a. Acute myocardial infarction (AMI) results from an imbalance between oxygen demand and oxygen supply to the myocardium. In 90 percent of the cases of AMI, this imbalance is preceded by atherosclerosis and decreased blood flow in the coronary arteries. The inadequate blood flow results in decreased oxygen delivery to the heart muscle, which causes ischemia, injury, and death of a portion of the myocardium (infarction).
b. Myocardial infarctions are described as being anterior, inferior, or posterior, depending upon the location of the infarcted area of the heart muscle. Infarcts can be further classified as being transmural or non-transmural. A transmural infarct (Non Q-Wave MI) is one that involves damage to the full thickness of the myocardium. A nontransmural MI involves only a partial thickness of the muscle.
c. In the majority of patients with AMI, chest pain is the major presenting symptom. The pain is usually substernal and may radiate to the neck, shoulders, arms, or epigastric area. The pain is described as heaviness, constriction, burning, or similar to indigestion. It is important to remember, however, that there may be little or no pain present at all. AMI can be very subtle, and often difficult to distinguish from angina. In addition to chest pain, symptoms of MI include shortness of breath, diaphoresis, weakness, fatigue, anxiety, nausea, vomiting, abnormal blood pressure, and abnormal heart rate.
d. Pain, anxiety, and arrhythmias occur in the early stages of MI. Ventricular fibrillation is the greatest threat to life in the first hours after MI. Medical management includes ECG monitoring, bedrest to reduce the workload of the heart, and intravenous therapy. Medications include morphine to reduce pain and relieve anxiety, vaso-dialators, beta blocker, calcium channel blockers and lidocaine as antiarrhythmic therapy.
e. Nursing management of a patient with AMI is intensive in nature, requiring close monitoring of the patient's status and progress, along with concurrent patient education. The nursing staff works closely with the physician, physical therapist, and dietician to develop an individualized rehabilitation plan for the patient. This post myocardial infarction rehabilitation plan, often referred to as the "MI protocol," takes the patient from complete bed rest during the first days of his MI to discharge from the hospital several weeks later. The protocol is a plan of progressive, monitored "steps" of increased activity and exercise, accompanied by intensive patient education. The rehabilitation plan is implemented upon physician's orders once the patient's condition is stable. Rehabilitation is advanced by the physician, who bases his decisions upon daily review of the patient's status and the information recorded by the nursing staff. Important information regarding patient tolerance and acceptance of the rehabilitation process is obtained by the nursing staff and recorded in the patient's chart.
f. Nursing care is directed toward three major considerations: observation and prevention of further myocardial damage and complications, promotion of an environment that allows for maximum comfort and rest, and patient education to fully prepare the patient for discharge.
(1) Observation and prevention include the following nursing considerations:
(a) Frequent monitoring of the patient's vital signs and ECG.
(b) Observation for signs of impending heart failure by close monitoring of intake and output, daily weight, breathe sounds, and serum enzymes.
(c) Careful assessment and documentation of each episode of chest pain to include severity, duration, medication given, and relief obtained.
(2) Promotion of a restful and comfortable environment includes the following nursing considerations:
(a) Provide emotional support to reduce anxiety and stress.
(b) Orient the patient to the coronary care unit (CCU) routine and environment. Take time to explain procedures.
(c) Schedule patient care activities carefully to avoid interrupting the patient's sleep.
(3) Patient education is necessary to prepare the patient for resuming life outside the hospital setting. The following nursing considerations should be included:
(a) Promote compliance with prescribed medications, diet, and other treatment measures by thoroughly explaining the need for each and the possible consequences of noncompliance.
(b) Review all activity limitations and restrictions.
(c) Counsel the patient on the action that should be taken when he is confronted with chest pain or other symptoms.
