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Heart Attack (MI) is one of the most
common life-threatening diseases. In the United States, it is the number one cause of
death. When a patient is having chest pain, this may indicate the presence of an MI and it
requires an immediate visit to the ER (emergency room). Although chest pain may indicate a
heart attack, other possible causes of chest pain can occur (select "Chest Pain"
in the health topics menu for more information).
Symptoms
Symptoms include chest discomfort that builds in intensity, eventually becoming severe and
unrelenting. The pain frequently lasts for 30 minutes or more and is usually located in
the region of the sternum, precordium, or epigastrium. Pain is usually characterized as
constricting, crushing, oppressing, or compressing but may be stabbing, boring,
knife-like, or burning. The discomfort often spreads to engulf both sides of the anterior
chest, with predilection for the left side. Pain of MI may radiate down the inner aspect
of the left arm, to the left or both shoulders, or to the jaw or interscapular region, or
both. Some patients with MI may have minimal or no chest discomfort. Patients are likely
to complain of associated feelings of weakness, cold perspiration, dizziness, palpitation,
and a sense of impending doom. In many individuals, the discomfort of MI is confused with
that of indigestion.
Diagnosis
1. Typical changes in the ECG are often seen in the case of an MI. However, MI can occur
in the absence of electrocardiographic changes.
2. Laboratory tests employed include:
(1) Creatine phosphokinase (CK).
(2) Glutamic-oxaloacetic transaminase (GOT).
(3) Lactic dehydrogenase (LDH).
(4) Newer serum tests.
Typical changes in the above are characteristic of an MI.
3. Echocardiography may be useful.
4. Radionuclide techniques are occasionally employed.
5. Cardiac catheterization and angiography. Patients with acute MI may undergo cardiac
catheterization under certain conditions.
6. The diagnosis of MI is made when patients meet the criteria indicated in one of the
following categories:
(1) Chest pain associated with development of characteristic changes in
ECG. The diagnosis is confirmed by obtaining one or more abnormal serum enzyme
determinations. The MB fraction of CK is the preferred enzyme.
(2) Chest pain associated with characteristic serum enzyme elevations.
(3) Atypical symptoms such as indigestion, syncope, shortness of
breath, or unusual fatigue associated with characteristic ECG changes and serum enzyme
abnormalities.
(4) Typical or atypical symptoms (as just noted) in association with
characteristic ECG or imaging changes.
Treatment
a. Thrombolytic therapy. There are presently substances that dissolve the clot in an MI.
However, prompt treatment is required since otherwise they have no effect. Typical
examples of these substances are streptokinase, urokinase, and tissue plasminogen
activator (TPA).
b. Anticoagulants. Anticoagulants (in particular heparin) are commonly used in patients
with acute MI. Aspirin has been shown to also be effective in preventing recurrence of MI
as well as preventing its occurrence in patients with unstable coronary artery disease.
c. Agents to reduce infarct size. A number of different agents have been shown to reduce
infarct size in experimental animals and clinical trials. The most important of these
agents are the beta-blockers.
d. Angiotensin converting-enzyme (ACE) inhibitors (i.e., captopril, enalapril, etc.) are
effective in managing left ventricular failure and have been shown to increase long-term
survival in patients with reduced left ventricular function (ejection fraction <40%)
following MI.
e. Analgesics. Morphine, hydromorphone (Dilaudid), and meperidine (Demerol) are opiate
analgesics that can be employed to relieve the discomfort of MI.
f. Sedation. Anxiety, like ischemic discomfort, activates the sympathetic nervous system
with potentially deleterious effects on the infarcted heart. Patients with acute MI should
be sedated.
g. Stool softeners and laxatives.
h. Diuretics. Patients who develop evidence of left ventricular failure following MI may
be candidates for diuretic therapy.
i. Digitalis. The use of digitalis glycosides in patients with acute MI is controversial.
j. Oxygen. In an effort to correct arterial hypoxia, which commonly occurs in patients
with MI, most coronary care units routinely administer supplemental inspiratory oxygen.
k. Activity. Current ambulation schedules for postinfarction patients are considerably
more liberal than earlier programs. Patients with uncomplicated MI (absent or short-lived
arrhythmias, left ventricular failure, pericarditis, etc.) may begin ambulation by day 3
after infarction. They can be discharged from the hospital in 5-7 days. Patients with
complicated MI remain in the hospital for 2 weeks or longer. Sexual activity between
familiar partners does not require marked increases in left ventricular work. Hence,
moderate sexual activity may be resumed a few days after patients are discharged from the
hospital.
l. Environmental and psychological support. Three psychological mechanisms occur commonly
in post-MI patients: anxiety, denial, and depression.
m. Pacemakers. These may be indicated for rhythm control when certain complications of an
MI occur.
n. Cardioversion. Electric reversion is reserved for arrhythmias that are so serious as to
require immediate termination or for arrhythmias that fail to respond to the
administration of antiarrhythmic medication.
o. Postinfarction rehabilitation. The objective of postinfarction rehabilitation is the
restoration of the individual's physiological, social, and vocational status.
p. Associated medical disorders. Hypertension, diabetes mellitus, and various forms of
hyperlipidemia commonly accompany coronary artery disease and MI. These conditions should
be sought and appropriate diagnostic and therapeutic measures instituted.
q. Specific complications following acute myocardial infarction should be treated.
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