Emergency Medicine Q & A, 2009, Pg

Emergency Medicine Q & A, 2009, Pg


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therapy to achieve additional antihypertensive effects. Captopril is contraindicated in
patients with bilateral renal artery stenosis, since a reduction in systemic arterial pressure may lead to progressive
renal hypoperfusion.
60 Emergency Medicine Q & A: Pearls of Wisdom ...
42. The most important effect of digitalis therapy in heart failure is:
a. Controlling the ventricular response of atrial \ufb01brillation.
b. Controlling paroxysmal atrial tachycardia with block or accelerated junctional rhythms.
c. Improving myocardial contractility, thus attenuating symptoms of congestive heart failure.
d. Improving myocardial contractility to improve survival.
e. Improving myocardial contractility and slowing the heart rate in high-output heart failure.
The answer is a. Digitalis has been used for years to treat chronic CHF. Digitalis enhances contractility, reduces the
heart\u2019s sympathetic response and controls the ventricular response (improving diastolic \ufb01lling time) to atrial
\ufb01brillation. Paroxysmal atrial tachycardia and accelerated junctional rhythms are common arrhythmias seen in
digitalis toxicity.
43. A 60-year-old man describes the onset of palpitations 8 hours ago that woke him from sleep. He has a
history of hypertension and paroxysmal atrial \ufb01brillation (AF). On presentation, he is noted to have a heart
rate in the 140s with blood pressure of 110/60 mmHg. Pertinent physical \ufb01ndings include mild basilar
crackles in his lungs, an irregularly irregular rhythm, and a nondisplaced point of maximal intensity. His
medications include aspirin and an ACE inhibitor. ECG con\ufb01rms the presence of AF. Your next step is to:
a. Perform synchronized cardioversion immediately.
b. Start metoprolol at 5 mg intravenously until the heart rate is 100/min, and follow this with oral metoprolol at
50 mg twice daily.
c. Begin heparin drip and cardiovert.
d. Perform transesophageal echocardiography to rule out thrombus, then cardiovert with 360 J synchronized to the
R wave.
e. Start oral dofetilide, intravenous heparin, and admit for anticoagulation with warfarin.
The answer is b. While the other answers can be part of the clinical options to restore sinus rhythm, the most
important immediate step is to control the ventricular response and prevent possible hemodynamic compromise.
Starting a type I-C agent without an atrioventricular nodal blocking agent can lead to an even faster ventricular
response. If sinus rhythm can be restored within 48 hours of the onset of atrial \ufb01brillation, then most patients do
not need transesophageal echocardiography or heparinization prior to cardioversion; however, if concern exists
about the duration of AF and its frequency, start rate control and anticoagulation. The patient can be treated
conservatively and cardioverted after 4 weeks of therapeutic International Normalized Ratio (INR) or have a
transesophageal echo and cardioversion immediately. In both circumstances, anticoagulate the patient for 3\u20134
weeks after conversion to sinus rhythm.
44. Three drugs which have been shown to decrease mortality in patients suffering an acute myocardial
infarction with ST-segment elevation are:
a. Calcium channel blockers, aspirin, and heparin.
b. Fibrinolytic agents, beta-blockers, and heparin.
c. Fibrinolytic agents, nitrates, and beta-blockers.
d. Fibrinolytic agents, aspirin, and ACE inhibitors.
e. Nitrates, aspirin, and heparin.
... CHAPTER 3 Cardiovascular Emergencies 61
The answer is d. Calcium channel blockers have no role in the treatment of acute MI with ST elevation and
actually may be harmful in this setting. Fibrinolytics, aspirin, and ACE inhibitors have been shown to reduce
mortality rates. Beta-blockers reduce mortality in patients with ventricular dysrhythmias or anterior wall MI, but
actually increase cardiogenic shock and death in patients who are hypotensive or have inferior wall ischemia.
Nitrates are useful for symptomatic relief and preload reduction, but have not been shown to affect mortality.
Heparin offers theoretical bene\ufb01t, but does not affect mortality rates.
45. The best choice for treatment of ventricular \ufb01brillation in a patient with hypothermia is:
a. Procainamide.
b. Lidocaine.
c. Amiodarone.
d. Atropine.
e. Adenosine.
The answer is c. Procainamide is arrhythmogenic for patients with hypothermia and should not be used. Lidocaine
is less effective in patients with hypothermia, and atropine is indicated for bradyarrhythmias. Adenosine is indicated
for the treatment of supraventricular arrhythmias, but not ventricular \ufb01brillation in hypothermia. Amiodarone is
the drug of choice.
46. An EKG \ufb01nding that suggests a pacemaker abnormality is:
a. Pacer spike smaller than 5 mm.
b. Lack of P wave.
c. Right bundle-branch block.
d. Left bundle-branch block.
e. Paced QRS complexes independent of intrinsic atrial depolarization.
The answer is c. The pacer spike is a narrow de\ufb02ection that is usually less than 5 mm in amplitude with a bipolar
lead con\ufb01guration and usually 20 mm or more in amplitude with a unipolar lead. A wide QRS complex appears
immediately after the stimulus artifact. Depolarization begins in the right ventricular apex, and the spread of
excitation does not follow normal conduction pathways. Characteristically, a left bundle-branch block conduction
pattern is seen. A right bundle-branch pattern is abnormal and suggests lead displacement. In VVI pacing, the
paced QRS complexes are independent of intrinsic atrial depolarization if present (AV dissociation).
47. Choose the correct statement about the patient with a transplanted heart:
a. Heart rate does not increase with stress or exercise.
b. The electrocardiogram frequently shows two P waves.
c. Exogenous vasopressors do not work in a transplanted heart.
d. Most antihypertensive agents are ineffective in a transplanted heart.
e. Atropine is very effective in treating an atrioventricular block.
The answer is b. The transplanted heart maintains a rate of 100\u2013110/min without vagal parasympathetic tone.
The electrocardiogram typically demonstrates two P waves, with one wave from the native sinus node in the
posterior right atrium, which is left in place with its vena caval connections during surgery, and the second from the
donor sinoatrial node, which should conduct to the ventricles as usual with a normal PR interval. The heart rate
can increase with exercise or stress through the effects of endogenous catecholamines, up to 70% of maximum for
age. Exogenous pressor drugs work well in the transplanted heart. Antihypertensive agents can be used to treat
hypertension, even of crisis proportions, as in the nontransplant patient. Atropine is ineffective at increasing the
sinus node rate or relieving atrioventricular block.
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CHAPTER 4 Cutaneous Emergencies
Stephanie Barbetta, MD
1. In examining a patient suspected of being infested with body lice:
a. Eggs and lice are usually limited to the patient\u2019s body and are unlikely to be found on clothing or possessions.
b. Egg casings are often found attached to the hairs of the arms and legs.
c. Lice infestation is a super\ufb01cial problem and should not cause adenopathy or fevers.
d. Small pruritic erythematous spots on the skin are often found.
e. Furrows are pathognomonic.
The answer is d. Body lice and eggs are typically found on the inner surfaces of clothes in contact with the skin.
The bites are small pruritic erythematous spots. Scratch marks may aid the diagnosis. Systemic reactions to lice
feces and saliva, as well as pyogenic infections may lead to fever and regional lymphadenopathy. Egg casings are
eccentrically located and \ufb01rmly bound to terminal (thick) hair shafts. It is unusual to \ufb01nd lice on the \ufb01ne (vellus)
hair of the body. Furrows are characteristic of infestation by scabies mites.
2. A 23-year-old woman complains of dysuria and her urine is dipstick positive for leukocyte