FIRST AID FOR THE USMLE
PRACTICE EXAMINATION 2026
QUESTIONS WITH ANSWERS
GRADED A+
1. What helps close a patent ductus arteriosus (PDA)?
• A) PGE1
• B) PGE2
• C) Indomethacin
• D) Alprostadil
• Correct ,,,,answer,,,: C) Indomethacin
• Rationale: Indomethacin, a prostaglandin inhibitor, helps close a
PDA by blocking the vasodilatory effects of PGE1 and PGE2.
Conversely, PGE1 and PGE2 are used to keep the PDA open in
ductal-dependent congenital heart diseases.
2. U waves on an ECG are caused by which condition?
• A) Hyperkalemia
• B) Hypokalemia, bradycardia
• C) Hypercalcemia
• D) Myocardial infarction
• Correct ,,,,answer,,,: B) Hypokalemia, bradycardia
, • Rationale: U waves are most commonly associated with
hypokalemia (low potassium levels) and bradycardia. They appear
as small deflections following the T wave and are best seen in the
precordial leads.
3. What murmurs are increased in the left lateral decubitus position?
• A) Aortic stenosis and pulmonic stenosis
• B) Mitral stenosis and mitral regurgitation; left-sided S3/S4
• C) Tricuspid regurgitation and VSD
• D) Pericardial friction rub
• Correct ,,,,answer,,,: B) Mitral stenosis and mitral regurgitation;
left-sided S3/S4
• Rationale: The left lateral decubitus position brings the heart closer
to the chest wall, making left-sided heart sounds and murmurs
(mitral valve sounds) more audible. This position is optimal for
auscultating mitral stenosis and regurgitation.
4. Contractility and stroke volume decrease with which of the
following?
• A) Increased cAMP
• B) β1-blockade, acidosis, hypoxia/hypercapnia, non-dihydropyridine
Ca2+ channel blockers
• C) Increased sympathetic stimulation
• D) Increased preload
, • Correct ,,,,answer,,,: B) β1-blockade, acidosis,
hypoxia/hypercapnia, non-dihydropyridine Ca2+ channel
blockers
• Rationale: Negative inotropic agents decrease contractility. β1-
blockers reduce cAMP; acidosis and hypoxia depress myocardial
function; non-dihydropyridine calcium channel blockers (verapamil,
diltiazem) reduce calcium influx, all decreasing contractility and
stroke volume.
5. Location of the pulmonic valve area for auscultation:
• A) Right 2nd intercostal space adjacent to sternum
• B) Left 2nd intercostal space adjacent to sternum
• C) Left 5th intercostal space, midclavicular line
• D) Left lower sternal border
• Correct ,,,,answer,,,: B) Left 2nd intercostal space adjacent to
sternum
• Rationale: The pulmonic area is located at the left 2nd intercostal
space along the sternal border. This is where pulmonic valve sounds
(S2 splitting, pulmonic stenosis, pulmonic regurgitation) are best
heard.
6. What sounds are best heard at the tricuspid area?
• A) Aortic stenosis and aortic regurgitation
• B) Pansystolic murmur: tricuspid regurgitation, VSD; Diastolic
murmur: tricuspid stenosis, ASD
, • C) Pulmonic stenosis and pulmonic regurgitation
• D) Pericardial knock
• Correct ,,,,answer,,,: B) Pansystolic murmur: tricuspid
regurgitation, VSD; Diastolic murmur: tronicuspid stenosis, ASD
• Rationale: The tricuspid area (left lower sternal border, 4th-5th
intercostal space) is optimal for auscultating right-sided heart
murmurs, including tricuspid regurgitation (pansystolic), VSD
(pansystolic), tricuspid stenosis (diastolic), and ASD.
7. What increases myocardial oxygen demand? (Mnemonic:
"myoCARDial")
• A) Increased Contractility, Increased Afterload, Increased heart
Rate, Increased Diameter (wall tension)
• B) Decreased contractility and afterload
• C) Decreased heart rate
• D) Vasodilation
• Correct ,,,,answer,,,: A) Increased Contractility, Increased
Afterload, Increased heart Rate, Increased Diameter (wall
tension)
• Rationale: Myocardial oxygen demand (MVO2) increases with
factors that increase cardiac work: enhanced contractility, elevated
afterload (pressure work), tachycardia, and increased ventricular
diameter (increased wall tension per Laplace's law).
8. What does the QRS complex represent on the cardiac cycle?
PRACTICE EXAMINATION 2026
QUESTIONS WITH ANSWERS
GRADED A+
1. What helps close a patent ductus arteriosus (PDA)?
• A) PGE1
• B) PGE2
• C) Indomethacin
• D) Alprostadil
• Correct ,,,,answer,,,: C) Indomethacin
• Rationale: Indomethacin, a prostaglandin inhibitor, helps close a
PDA by blocking the vasodilatory effects of PGE1 and PGE2.
Conversely, PGE1 and PGE2 are used to keep the PDA open in
ductal-dependent congenital heart diseases.
2. U waves on an ECG are caused by which condition?
• A) Hyperkalemia
• B) Hypokalemia, bradycardia
• C) Hypercalcemia
• D) Myocardial infarction
• Correct ,,,,answer,,,: B) Hypokalemia, bradycardia
, • Rationale: U waves are most commonly associated with
hypokalemia (low potassium levels) and bradycardia. They appear
as small deflections following the T wave and are best seen in the
precordial leads.
3. What murmurs are increased in the left lateral decubitus position?
• A) Aortic stenosis and pulmonic stenosis
• B) Mitral stenosis and mitral regurgitation; left-sided S3/S4
• C) Tricuspid regurgitation and VSD
• D) Pericardial friction rub
• Correct ,,,,answer,,,: B) Mitral stenosis and mitral regurgitation;
left-sided S3/S4
• Rationale: The left lateral decubitus position brings the heart closer
to the chest wall, making left-sided heart sounds and murmurs
(mitral valve sounds) more audible. This position is optimal for
auscultating mitral stenosis and regurgitation.
4. Contractility and stroke volume decrease with which of the
following?
• A) Increased cAMP
• B) β1-blockade, acidosis, hypoxia/hypercapnia, non-dihydropyridine
Ca2+ channel blockers
• C) Increased sympathetic stimulation
• D) Increased preload
, • Correct ,,,,answer,,,: B) β1-blockade, acidosis,
hypoxia/hypercapnia, non-dihydropyridine Ca2+ channel
blockers
• Rationale: Negative inotropic agents decrease contractility. β1-
blockers reduce cAMP; acidosis and hypoxia depress myocardial
function; non-dihydropyridine calcium channel blockers (verapamil,
diltiazem) reduce calcium influx, all decreasing contractility and
stroke volume.
5. Location of the pulmonic valve area for auscultation:
• A) Right 2nd intercostal space adjacent to sternum
• B) Left 2nd intercostal space adjacent to sternum
• C) Left 5th intercostal space, midclavicular line
• D) Left lower sternal border
• Correct ,,,,answer,,,: B) Left 2nd intercostal space adjacent to
sternum
• Rationale: The pulmonic area is located at the left 2nd intercostal
space along the sternal border. This is where pulmonic valve sounds
(S2 splitting, pulmonic stenosis, pulmonic regurgitation) are best
heard.
6. What sounds are best heard at the tricuspid area?
• A) Aortic stenosis and aortic regurgitation
• B) Pansystolic murmur: tricuspid regurgitation, VSD; Diastolic
murmur: tricuspid stenosis, ASD
, • C) Pulmonic stenosis and pulmonic regurgitation
• D) Pericardial knock
• Correct ,,,,answer,,,: B) Pansystolic murmur: tricuspid
regurgitation, VSD; Diastolic murmur: tronicuspid stenosis, ASD
• Rationale: The tricuspid area (left lower sternal border, 4th-5th
intercostal space) is optimal for auscultating right-sided heart
murmurs, including tricuspid regurgitation (pansystolic), VSD
(pansystolic), tricuspid stenosis (diastolic), and ASD.
7. What increases myocardial oxygen demand? (Mnemonic:
"myoCARDial")
• A) Increased Contractility, Increased Afterload, Increased heart
Rate, Increased Diameter (wall tension)
• B) Decreased contractility and afterload
• C) Decreased heart rate
• D) Vasodilation
• Correct ,,,,answer,,,: A) Increased Contractility, Increased
Afterload, Increased heart Rate, Increased Diameter (wall
tension)
• Rationale: Myocardial oxygen demand (MVO2) increases with
factors that increase cardiac work: enhanced contractility, elevated
afterload (pressure work), tachycardia, and increased ventricular
diameter (increased wall tension per Laplace's law).
8. What does the QRS complex represent on the cardiac cycle?
