Download Chemistry Problem Solving Drill

USMLE Step 1 - Problem Drill 15: Cardiovascular System
Question No. 1 of 10
Instructions: (1) Read the problem statement and answer choices carefully, (2) Work the problems
on paper as needed, (3) Pick the answer, and (4) Review the core concept tutorial as needed.
1. This type of heart murmur, whose phonocardiogram is shown Below, is heard
best at the left lower sternal border at the third and fourth intercostal space with
the patient sitting up, leaning forward and fully exhaled.
Question #01
(A) Mitral stenosis
(B) Patent ductus arteriosus (PDA)
(C) Aortic stenosis
(D) Tricupsid regurgiation
(E) Aortic regurgitation
A. Incorrect!
Mitral Stenosis is heard best with the bell in the left lateral decubitus position.
B. Incorrect!
Patent Ductus Arteriosus (PDA) is heard best at the left first and second intercostal
space.
C. Incorrect!
Aortic stenosis is heard best at the second intercostal space.
Feedback
D. Incorrect!
Tricupsid regurgiation is heard best at the left lower sternal border and and is
characterized by a holosystolic (high-pitched) murmur.
E. Correct!
Aortic regurgitation is heard best at the left lower sternal border at the third and
fourth intercostal space with the patient sitting up, leaning forward and fully
exhaled.
Auscultation is helpful in the management of many heart diseases. Aortic
regurgitation is heard best at the left lower sternal border at the third and fourth
intercostal space with the patient sitting up, leaning forward and fully exhaled.
Diastolic (high-pitched) decrescendo murmur often associated with LVH. Widened
pulse pressure, bisferious pulse, Traube sign, Quincke sign and Corrigan pulse may
be seen with chronic aortic insufficiency.
Solution
(E)Aortic regurgitation
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Question No. 2 of 10
Instructions: (1) Read the problem statement and answer choices carefully, (2) Work the problems
on paper as needed, (3) Pick the answer, and (4) Review the core concept tutorial as needed.
2. Ultrasound of a female fetus reveals coarctation of the aorta. What is a likely
cause of this congenital cardiac defect?
Question #02
(A) Marfan’s syndrome
(B) Turner’s syndrome
(C) Down’s syndrome
(D) 22q11 syndrome
(E) Wolff-Parkinson White syndrome
A. Incorrect!
A congenital cardiac defect associated with Marfan’s syndrome is aortic
insufficiency.
B. Correct!
A congenital cardiac defect associated with Turner’s syndrome is coarctation of the
aorta.
C. Incorrect!
Congenital cardiac defects associated with Down’s syndrome are ASD, VSD, or AV
septal defect.
Feedback
D. Incorrect!
Congenital cardiac defects associated with 22q11 syndrome are truncus arteriosus
or tetralogy of Fallot.
E. Incorrect!
In Wolff-Parkinson White syndrome an accessory atrioventricular connection is
present.
Different disorders can contribute to congential cardiac defects. A congenital cardiac
defect associated with Turner’s syndrome is coarctation of the aorta.
(B)Turner’s syndrome
Solution
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Question No. 3 of 10
Instructions: (1) Read the problem statement and answer choices carefully, (2) Work the problems
on paper as needed, (3) Pick the answer, and (4) Review the core concept tutorial as needed.
3. The __________ is an index of ventricular contractility.
Question #03
(A) Preload
(B) Ejection fraction
(C) Cardiac output
(D) Pressure gradient
(E) Afterload
A. Incorrect!
The preload is the ventricular end diastolic volume (EDV).
B. Correct!
The ejection fraction (EF) is an index of ventricular contractility.
C. Incorrect!
Cardiac output is stroke volume x heart rate.
Feedback
D. Incorrect!
The pressure gradient is the difference in the pressure between the beginning and
the end of the vessel.
E. Incorrect!
The afterload is the mean arterial pressure.
The ejection fraction (EF) is an index of ventricular contractility. It is calculated
using the following formula:
EF = SV/EDV = EDV-ESV /EDV
EF is normally greater than 55%.
(B)Ejection fraction
Solution
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Question No. 4 of 10
Instructions: (1) Read the problem statement and answer choices carefully, (2) Work the problems
on paper as needed, (3) Pick the answer, and (4) Review the core concept tutorial as needed.
4. As shown below, ____ of the cardiac cycle is the rapid filling period just after the
mitral valve opening.
Question #04
(A) Phase
(B) Phase
(C) Phase
(D) Phase
(E) Phase
1
2
3
4
5
A. Incorrect!
Phase 1 of the cardiac cycle, isovolumetric contraction, is the period between mitral
valve closure and aortic valve opening during which the highest O2 consumption
occurs.
B. Incorrect!
Phase 2 of the cardiac cycle, systolic ejection, is the period between the aortic valve
opening and closing.
C. Incorrect!
Phase 3 of the cardiac cycle, isovolumetric relaxation, occurs between the time when
the aortic valve closes and the mitral valve opens.
Feedback
D. Correct!
Phase 4 of the cardiac cycle is the rapid filling period just after the mitral valve
opening.
E. Incorrect!
Phase 5 of the cardiac cycle, reduced filling is the period just before the mitral valve
closes.
The cardiac cycle is described as one complete sequence of contraction and
relaxation and can be divided into 5 phases. Phase 4 is the rapid filling period just
after the mitral valve opening.
Solution
(D)Phase 4
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Question No. 5 of 10
Instructions: (1) Read the problem statement and answer choices carefully, (2) Work the problems
on paper as needed, (3) Pick the answer, and (4) Review the core concept tutorial as needed.
5. The factors determining autoregulation of the ____ are local metabolites including
O2, adenosine and NO.
Question #05
(A) Heart
(B) Brain
(C) Kidneys
(D) Lungs
(E) Skin
A. Correct!
The factors determining autoregulation of the heart are local metabolites including
O2, adenosine and NO.
B. Incorrect!
The factors determining autoregulation of the brain are local metabolites including
CO2.
C. Incorrect!
The factors determining autoregulation of the kidneys are myogenic and
tubuloglomerular feedback.
Feedback
D. Incorrect!
The factor determining autoregulation of the lungs is hypoxia.
E. Incorrect!
The factor determining autoregulation of the skin is sympathetic stimulation.
Various organs of the body are capable of maintaining the blood pressure through
autoregulation. Each one has its own mechanism of doing so. The factors
determining autoregulation of the heart are local metabolites including O2,
adenosine and NO.
(A)Heart
Solution
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Question No. 6 of 10
Instructions: (1) Read the problem statement and answer choices carefully, (2) Work the problems
on paper as needed, (3) Pick the answer, and (4) Review the core concept tutorial as needed.
6. ECG of a 54 year old man reveals a constant PR interval followed by a nonconducted P wave. Which if the following diagnoses fits this scenario?
Question #06
(A) First degree AV
(B) Second degree AV B Mobitz type I
(C) Second degree AV Mobitz type II
(D) Third degree AV
(E) Wenckebach AV
A. Incorrect!
First degree AV block is characterized by a PR interval that is prolonged for more
than 0.2 secs.
B. Incorrect!
Second-degree AV B Mobitz type I block is characterized by a progressive
lengthening of the PR interval followed by a non conducted P wave leading to a
dropped QRS complex.
C. Correct!
Second Degree AV Mobitz Type II block is characterized by a constant PR interval
either normal or prolonged followed by a non conducted P wave.
Feedback
D. Incorrect!
Third Degree AV Block is characterized by independent atrial and ventricular activity.
E. Incorrect!
Wenckebach AV block is another name for second-degree AV B Mobitz type I block.
AV Block describes a group of disorders associates with conduction disturbances
within the AV junctional tissue. The conduction disturbance can be partial (first or
second degree) or complete (third degree).
Second Degree AV Mobitz Type II block is characterized by a constant PR interval
either normal or prolonged followed by a non conducted P wave. The QRS complex is
usually quite wide and it is often found as 2:1 block where there are 2 P waves to 1
QRS response.
Solution
(C)Second degree AV Mobitz type II
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Question No. 7 of 10
Instructions: (1) Read the problem statement and answer choices carefully, (2) Work the problems
on paper as needed, (3) Pick the answer, and (4) Review the core concept tutorial as needed.
7. Blood analysis of a 38 year old woman reveals elevated cholesterol, suggesting
hyperlipidemia. You also notice the presence of ____, which are plaques or nodules
composed of lipid laden histocyes in the skin, particularly the eyelids.
Question #07
(A) Artheromas
(B) Xanthomas
(C) Tendinous xanthoma
(D) Corneal arcus
(E) Arcus senilis
A. Incorrect!
Atheromas are plaques in the walls of the blood vessels.
B. Correct!
A sign of hyperlipidemia is the presence of xanthomas, which are plaques or nodules
composed of lipid laden histocyes in the skin, particularly the eyelids.
C. Incorrect!
Tendinous xanthomas are lipid deposits in the tendon, particularly the Achilles
tendon.
Feedback
D. Incorrect!
Corneal arcus is a deposit of lipid in the cornea seen as a ring around the cornea.
E. Incorrect!
Arcus senilis is another name for corneal arcus.
Hyperlipidemia can be signalled by various other conditions including xanthomas,
which are plaques or nodules composed of lipid laden histocyes in the skin,
particularly the eyelids.
(B)Xanthomas
Solution
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Question No. 8 of 10
Instructions: (1) Read the problem statement and answer choices carefully, (2) Work the problems
on paper as needed, (3) Pick the answer, and (4) Review the core concept tutorial as needed.
8. You are rounding at the hospital when you are urgently called into a room and
asked to examine an infant. When you enter the room you immediately notice that
despite the baby being awake, and rooting for food it is cyanotic in color.
Respirations look comfortable and oxygen administration does not seem to be
helping the situation. As you examine the baby you notice that while the precordium
is quiet, a mild RV heave is present. A chest x-ray is ordered which shows a bootshaped heart. This baby has ____, which is the most common form of cyanotic
congenital heart disease.
Question #08
(A) Transposition of the great vessels
(B) Coarctation of the aorta
(C) Teratology of fallot
(D) Eisenmenger’s syndrome
(E) Patent ductus arteriosus
A. Incorrect!
In transposition of the great vessels the chest radiograph shows narrowing at the
base of the heart in the region of great vessels. Right atrial enlargement, RVH and
occassionally niventricular hypertrophy.
B. Incorrect!
With coarctation of the aorta symptoms include high blood pressure in the upper
extremities and low blood pressure in the lower extremities. Chest x-ray changes
may include notching on the lower ribs, left ventricular hypertrophy, and dilatation
of the aorta proximal to the stricture.
C. Correct!
This baby has Teratology of fallot, which is the most common form of cyanotic
congenital heart disease.
Feedback
D. Incorrect!
In Eisenmenger’s syndrome uncorrected VSD, ASD or PDA leads to progressive
pulonary hypertension. As pulmonary resistance increases, the shunt reverses from
L to R to R to L causing cyanosis. Patients usually have a history or murmur or
cyanosis during infancy.
E. Incorrect!
In Patent ductus arteriosus there is a widened pulse pressure and loud S2. A
continuous murmur may be heard over the left pulmonary area and thrill is
common. While echocardiography/Doppler is helpful, the lesion is best visualized by
MRI, CT or contrast angiography.
Solution
Teratology of Fallot is the most common form of cyanotic congenital heart disease.
The patients with TOF is typically a blue baby. There is usually a history of exercise
intolerance and squatting during childhood. Worsening cyanosis also occurs during
exercise because of the associate systemic vasodilation and increased right to left
shunt. Physical examination reveals cyanosis and less frequently clubing. The
precordium is generally quiet, although a mild RV heave may be present. The
intensity and duration of the pulmonic flow murmur vary with the degree of PS. P2 is
usually absent. Patients that have classic Blalock-Taussig shunt , anastomosis of the
subclavian to the side of the pulmonary artery will have an absent pulse in the
ipsilateral arm and a continuous murmur as long as the shunt is patent and
functioning properly.P waves are usually normal. Chest radiograph shows a classic
boot shaped heart in severe cases without left to right shunt, LV enlargement and
post stenotic pulmonary artery dilatation in milder cases.
(C)Teratology of fallot
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Question No. 9 of 10
Instructions: (1) Read the problem statement and answer choices carefully, (2) Work the problems
on paper as needed, (3) Pick the answer, and (4) Review the core concept tutorial as needed.
9. You are starting your patient on an antihypertensive drug for their elevated blood
pressure. You know from the patient’s history that they have at times trouble with
hypoglycemia. With this in mind you plan to avoid prescribing ____ as you do not
want to take a chance that the side effects of the new medicine will further
contribute to their hypoglycemia problems.
Question #09
(A) Hydralazine
(B) Minoxidil
(C) Nitroprusside
(D) Verapamil
(E) Diazoxide
A. Incorrect!
Side effects associated with Hydralazine are nausea, headache, lupus-like syndrome,
reflex tachycardia, angina, and salt retention.
B. Incorrect!
Side effects associated with Minoxidil are hypertrichosis, pericardial effusion, reflex
tachycardia, angina, and salt retention.
C. Incorrect!
A side effect associated with Nitroprusside is cyanide toxicity.
Feedback
D. Incorrect!
Side effects associated with verapamil are dizziness, flushing, nausea, constipation
and AV block.
E. Correct!
You want to avoid prescribing Diazoxide as an associated side effect is
hypoglycemia.
Vasodilators produce dilatation of the blood vessels and include ACE inhibitors,
nitrates as well as direct acting vasodilators. Direct acting vasodilators act
predominantly in the arterioles reducing peripheral resistance and producing a fall in
blood pressure. A side effects associated with Diazoxide is hypoglycemia.
Solution
(E)Diazoxide
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Question No. 10 of 10
Instructions: (1) Read the problem statement and answer choices carefully, (2) Work the problems
on paper as needed, (3) Pick the answer, and (4) Review the core concept tutorial as needed.
10. ____ is frequently used to prevent ventricular tachycardia.
Question #10
(A) Amiodarone
(B) Verapamil
(C) Diltiazem
(D) Sotalol
(E) Dofelitide
A. Correct!
Amiodarone is frequently used in the prevention of ventricular tachycardia.
B. Incorrect!
Verapamil is primarily used to manage supra-ventricular tachycardia.
C. Incorrect!
Diltiazem is primarily used for supraventricular arrhythmias including rate control in
atrial fibrillation.
Feedback
D. Incorrect!
Sotalol is used in the maintenance of sinus rhythm in patients with atrial fibrillation.
E. Incorrect!
Dofelitide is used in the maintenance of sinus rhythm in patients with atrial
fibrillation.
Class III drugs prolong the refractory period of the myocardium, thus suppressing
re-entrant rhythms. Amiodarone is the first agent in this group. It prolongs the
cardiac action potential and increases the refractory period making it a useful agent
in ventricular and supraventricular dysrhythmias. It is used in the prevention of
ventricular tachycardia and is preferred over bretylium in most settings.
Solution
(A)Amiodarone
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