37.The answer is e.(Roberts and Hedges, pp 283-285.)The patient’s ECG
reveals third-degree complete heart block.It is a disorder of the cardiac-
conduction system, where there is no conduction through the AV node.
This may occur secondary to MI, drug intoxication, infection, or infiltrative
diseases. On the ECG complete heart block is represented by QRS com-
plexes being conducted at their own rate and independent of the P waves.
Individuals with second-degree type II or third-degree complete heart
block are considered unstable. External pacing padsshould be placed on
them, followed by a transvenous pacer if their BP is unstable. They may
require a permanent pacemaker for irreversible complete heart block.
(a)Clearly this patient has an unstable rhythm and should not be dis-
charged home. (b)The patient should receive aspirin and have cardiac bio-
markers obtained, however, the ABCs must be followed and the patient’s
rhythm is currently unstable. (c)Placement of the magnet over the pace-
maker turns off the sensing function of the pacemaker and temporarily con-
verts the pacemaker from the demand mode to a fixed-rate mode at a rate
typically of 70. This assesses whether the pacing function is intact and the
pacing stimulus can capture the myocardium. There is no evidence in this
patient’s medical history that she has a pacemaker. (d)Holter monitoring
and echocardiogram are generally used to continuously monitor a patient’s
rhythm and cardiac function. This patient will likely undergo rhythm- and
function-assessment as an inpatient.
38.The answer is d.(Burnette, 2006.)Often young people are afraid to
disclose a history of drug use. Cocaineis well-known to cause acute MI in
young,otherwise healthy individuals. Patients with cocaine-related MI
often have fixed atherosclerotic lesions. Although these lesions may them-
selves be of clinical significance, cocaine-induced elevations in pulse and BP
increase myocardial work. The additional metabolic requirements that result
may convert an asymptomatic obstruction into one of clinical significance.
Cocaine use combined with ethanol consumption produces cocaethylene, a
longer-acting and more toxic by-product.
(a)Although cigarette smoking is a major risk factor for CAD, this
individual would not develop enough plaque after only 3 months. The
patient has no other cardiac risk factors. He puts himself at much greater
risk if he continues to smoke cigarettes. (b)If his grandfather or father had
a heart attack at age 40 or younger, there would be concern about his fam-
ily history. A heart attack in a related family member at age 80 is not a risk
44 Emergency Medicine