Cardiology Clinical Case / MCQS / Uworld for Usmle step 2 / case 3 with answer and explanation and references and Educational objective
A
52-year-old man comes to the emergency department with shortness of breath and
dry cough. The patient has been feeling weak over the last several days with
some dyspnea on exertion, which he attributes to work -related stress and
fatigue. Earlier this morning, he woke up with persistent breathing difficulty
that prompted him to come to the emergency department. The patient has a
history of mild intermittent asthma for which he occasionally uses an albuterol
inhaler. His family history is insignificant. The patient's temperature is 37.1
C (98.8 F), blood pressure is 117/72 mm Hg, pulse is 89/min, and respirations
are 18/min. Laboratory analysis reveals a markedly elevated serum brain
natriuretic peptide level. Which of the following clinical signs would best
correlate with this finding in this patient?
|
A Cyanosis B. Extremity edema C. Neck bruit D. Periumbilical bruit E. Third heart sound F. Wheezing |
Answer : E
Explanation :
This
clinical presentation - progressive dyspnea, fatigue, and elevated brain
natriuretic peptide (BNP) levels- is consistent with congestive heart failure
(CHF). BNP is a natriuretic hormone released from ventricular myocytes in
response to high ventricular filling pressures and wall stress in patients with
CHF. It is derived from the cleavage of the prohormone proBNP, which produces a
biologically active BNP and an inert N-terminal proBNP (NT-proBNP). Elevated
levels of circulating BNP or NT-proBNP correlate with the severity of left
ventricular systolic dysfunction. Conversely, normal values have a very high
negative predictive value for CHF as a cause of dyspnea and should prompt a
search for noncardiac causes of dyspnea.
The third
heart sound (S3) is a low-frequency diastolic sound produced by the passive
ventricular filling during early diastole; it is best heard over the cardiac
apex in the left lateral decubitus position. An abnormal S3 (louder and higher
pitch, S3 gallop) is commonly heard in patients with CHF due to left
ventricular systolic dysfunction (up to 99% specificity), and it correlates
with elevated left atrial and/or ventricular filling pressures and serum BNP
levels.
(Choice
A) Cyanosis can occur in patients with intrinsic lung disease or congenital
heart defects with right to left shunting (Eisenmenger syndrome). but it would
be rare in CHF unless there is marked hypoperfusion (eg, hypotension , cold and
clammy extremities) .Cyanosis would not correlate with BNP levels.
(Choice
B) Peripheral edema is one of the signs of CHF with volume overload; however,
compared to S3, it is less specific to the diagnosis of CHF and correlates less
closely with BNP levels. Peri pheral edema can be seen with several noncardiac
conditions, including inferior vena cava obstruction, cirrhosis, and lower
extremity venous insufficiency.
(Choice
C) Neck bruits can be present in patients with carotid artery stenosis.
(Choice
D) An abdominal or periumbilical bruit that lateralizes to one side can be
heard in patients with renal artery stenosis.
(Choice
F) Although wheezing can sometimes be heard in patients with a CHF exacerbation
due to bronchial wall edema, in general it is a sign of bronchial constriction
and is present in patients with asthma or chronic obstructive pulmonary disease
exacerbation. BNP levels are typically not elevated in patients with dyspnea
due to pulmonary or noncardiac causes.
Educational
objective:
Elevated
brain natriuretic peptide levels and an audible third heart sound are signs of increased
cardiac filling pressures and are noted in patients with congestive heart
failure due to left ventricular systolic dysfunction.
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