■ PERSPECTIVE
Nearly 6 million patients present to the emergency depart-
ment (ED) each year with complaints of chest pain, constitut-
ing 5% of all patients seen in EDs in the United States.1 Chest
pain is a symptom caused by several life-threatening diseases
and has a broad differential diagnosis. It is complicated by a
frequent disassociation between intensity of symptoms and
signs and seriousness of underlying pathology.
Epidemiology
The epidemiology of the critical diagnoses causing chest pain
varies widely. Acute coronary syndromes (ACS), aortic dissec-
tion, pulmonary embolism (PE), pneumothorax, pericarditis
with tamponade, and esophageal rupture are potentially cata-
strophic causes of chest pain. Due to its high incidence and
potential lethality, ACS is the most significant potential diag-
nosis in the ED. Of all deaths in the United States, 36% are
attributed to cardiovascular diseases; these account for approx-
imately 870,000 deaths per year.2 Historically, emergency phy-
sicians misdiagnose 3 to 5% of myocardial infarctions (MIs),
accounting for 25% of malpractice losses in emergency medi-
cine.3,4 Thoracic aortic dissection has an incidence of 0.5 to 1
per 100,000 population with a mortality rate exceeding 90% if
misdiagnosed. The true incidence of PE is unclear, with esti-
mates of 70 per 100,000. This equates to approximately 100,000
PE cases per year in the United States.5 Although the inci-
dence of tension pneumothorax is also unclear, the incidence
of spontaneous pneumothorax ranges from 2.5 to 18 per
100,000 total patients. The total incidence of esophageal
rupture is 12.5 cases per 100,000 persons. The true incidence
of pericarditis is unknown, but is diagnosed in 1 of every 1000
hospital admissions.6 Up to 5% of ED chest pain patients
without acute ST elevation MI may have pericarditis.7
Pathophysiology
Afferent fibers from the heart, lungs, great vessels, and esopha-
gus enter the same thoracic dorsal ganglia. Through these
visceral fibers, each organ produces the same indistinct quality
and location of pain. The quality of visceral chest pain varies
widely and is described as “burning,” “aching,” “stabbing,” or
“pressure.” Since dorsal segments overlap three segments
above and below a level, disease of a thoracic origin can
produce pain anywhere from the jaw to the epigastrium. Radi-
ation of pain is caused by somatic afferent fibers synapsing in
the same dorsal root ganglia as the thoracic viscera. This stimu-
lation can “confuse” the patient’s central nervous system
into misperceiving that the pain originates in the arms or
shoulders.
■ DIAGNOSTIC APPROACH
Differential Considerations
Due to the indistinct nature of visceral pain, the differential
diagnosis of chest pain is broad and includes many of the most
critical diagnoses in medicine and many nonemergent condi-
tions (Table 18-1).
Rapid Stabilization and Assessment
The initial questions are, “Must I intervene immediately?”,
and “What are the life-threatening possibilities in this patient?”
The answers are usually apparent within the first few minutes
after assessing the patient’s appearance and vital signs. One of
the critical diagnoses is tension pneumothorax. If a patient
presents with chest pain, respiratory distress, shock, and uni-
lateral reduction or absence of breath sounds, immediate
intervention with needle or tube thoracostomy is required.
Additionally, patients with severe derangements in vital signs
require stabilizing treatment during a search for the precipitat-
ing cause. Patients who present with respiratory distress
require immediate intervention and lead the emergency phy-
sician to consider a more serious cause of the pain (Fig. 18-1;
also see Chapter 17).
All patients, except those with obvious benign causes of
chest pain, must have an electrocardiogram (ECG) within
minutes of reporting their pain. This ECG should be read for
acute MI by the emergency physician as soon as it is com-
pleted. Patients with positive ECG findings and those consid-
ered at high risk are triaged directly to the treatment area and
monitored. Symptomatic derangements in vital signs are
addressed. If vital signs are stable, a focused history and physi-
cal examination are performed. Most patients also require a
chest radiograph to evaluate the chest pain. If a cardiac cause
is suggested and vital signs are stable, pain relief with nitro-
glycerin (0.4 mg sublingual every 3–5 minutes) may be appro-
priate. Aspirin (81–325 mg) is a consideration for patients
without hemorrhagic disorders, known allergies, or vascular
dissections. Clopidogrel (loading dose 300 mg) or other anti-
132
Chapter 18 Chest Pain
James E. Brown and Glenn C. Hamilton
