(b)Thrombolytics are reserved for patients who are hemodynamically
unstable.(c, d, and e)Any of these diagnostic studies should be performed
to confirm the diagnosis of PE. Because significant time may elapse until
the study is performed, and there is a risk that the clot will propagate, anti-
coagulant therapy should be initiated.
42.The answer is c.(Rosen, pp 1092-1096.)This patient has a ventricular
tachycardiadefined by a QRS complex greater than 120 msand a rate
greater than 100 beats per minute.Ventricular tachycardia is the result of
a dysrhythmia originating within or below the termination of the His bundle.
Most patients with ventricular tachycardia have underlying heart disease.
Treatment begins with assessing whether or not the patient is stable. If the
patient shows signs of instability, such as hypotension or altered mental sta-
tus, then cardioversion should be performed. However, if the patient is sta-
ble, medications can be administered to treat the dysrhythmia. Amiodarone,
a class III antidysrhythmic that has pharmacologic characteristics of all four
classes, is considered a first-line agent in treating ventricular dysrhythmias.
(a)Digoxin, a cardiac glycoside, has positive inotropic effects on the
heart and slows conduction through the AV node. It should not be used to
treat ventricular dysrhythmias. (b)Diltiazem, a CCB, acts on the AV node to
slow cardiac conduction and will not treat ventricular tachycardia. In addi-
tion, it can lead to hypotension in patients with ventricular tachycardia sec-
ondary to its peripheral dilatory effects. (d)Adenosine, an ultrashort-acting
AV nodal blocking agent, is typically used to treat supraventricular tachy-
cardias. (e)Bretylium is no longer available in the United States as it has a
poor safety profile.
43.The answer is c.(Rosen, pp 1011-1015.)The patient exhibits unstable
angina, which is defined as new-onset angina, angina occurring at rest lasting
longer than 20 minutes, or angina deviating from a patient’s normal pattern.
Unstable angina is considered the harbinger of an acute MI and, therefore,
should be evaluated and treated aggressively. Unstable angina is one of the
three diagnoses that make up ACS, the other two being stable angina and
acute MI (ST or non–ST elevation). Patients may be pain-free and have nega-
tive cardiac biomarkers with unstable angina. In general, unstable angina is
treated with oxygen, aspirin, clopidogrel, low molecular weight or unfrac-
tionated heparin, and further risk stratification in the hospital.
(a)Variant or Prinzmetal angina is caused by coronary artery vasospasm at
rest with minimal coronary artery disease. It is sometimes relieved by exercise
46 Emergency Medicine