10 USMLE Cardiology Questions with Answers and Explanations (Set 2)

These 10 USMLE cardiology practice questions (Set 2) cover murmurs, atrial fibrillation, chest pain work-up, endocarditis in IV drug users, hypertensive emergency, bradycardia, right ventricular infarction, SVT, pulmonary embolism and atrial myxoma. Each question includes the correct answer and an explanation.

Written by Dr. Ray Makar, MD, author of the Repeated USMLE Questions eBook series.

Prefer video? Watch daily USMLE case questions on MedFocus by Dr. Ray on YouTube.

How to use this page: read the question, pick your answer, then tap Show Answer and Explanation.

Questions

Question 1. An 18 year-old student visits her physician for a routine physical examination. She has no complaints. Physical examination is unremarkable except for a mid-systolic click followed by a late systolic murmur heard at the lower left sternal border and apex. The murmur duration increases in standing and shortens with squatting. Electrocardiogram (ECG) shows no abnormalities. Which of the following is the most likely diagnosis of this condition?

A- Mitral stenosis
B- Aortic stenosis
C- Mitral valve prolapse
D- Tricuspid regurgitation
E- Dilated cardiomyopathy

The only diagnosis that matches the described murmur is mitral valve prolapse. Patients with MVP are usually asymptomatic and only diagnosed accidently or due to progress to mitral regurgitation. Normal ECG findings support this diagnosis. Mitral valve prolapse is confirmed by echocardiography.
The correct answer is C

 

Question 2. A 57 year-old man presents to the ER complaining of sudden dizziness and heart racing for 2 hours. He is a CEO of a big corporation and those symptoms started during a stressful meeting. At first, he felt irregular heartbeats and ignored it but he felt dizzy soon after and his staff drove him to the ER. There is NO chest pain, shortness of breath or loss of consciousness. His vital signs are temp 97.8 F, Pulse 138/min and irregular, blood pressure 107/60 and oxygen saturation is 96% on room air. His ECG shows irregular irregularity with absence of P waves. What is the appropriate treatment to improve his symptoms in this current situation?

A- Metoprolol
B- Aspirin
C- Heparin
D- Cardioversion
E- Refer to cardiologist

This is most probably a case of atrial fibrillation. The next appropriate step of action is to improve the rate in order to improve the symptoms as the question specifies it. The drug of choice to improve the rate is metoprolol. The patient may need cardioversion later in the process but it is not the appropriate first step and the patient condition needs to be stable before taking any further action.
The correct answer is A

 

Question 3. A 45-year old man presents to the emergency room complaining of breathing difficulty, palpitations, dizziness and chest pain for 15 minutes. He is a new employee at the hospital. He was waiting for a meeting when he experienced these symptoms. He had 3 similar episodes during the past 3 months but they resolved spontaneously. His medical and surgical histories are unremarkable. He has no family history of cardiac disease or sudden death. On examination, he is anxious, vital signs are within normal limits and heart and chest examinations are normal. What is the next step of management for this patient?

A- Assurance and send him home for the rest of the day
B- 12-Lead ECG, random blood glucose and thyroid panel
C- Psychotherapy and alprazolam
D- Call cardiology department and prepare for PCI

Any case of chest pain in middle aged or old male patients is considered heart attack until proved otherwise. ECG is the next step and glucose and thyroid panel to exclude other causes of dizziness.
The correct answer is B

 

Question 4. A 40-year-old man with a long history of intravenous drug addiction presents to the emergency room complaining of fever, anorexia, malaise, shortness of breath, cough and chest pain for 2 days. On physical examination, temperature is 102.7 F, Pulse is 110/min. and blood pressure is 110/66. Irregular erythematous nodules are seen on his hands and feet. Which of the following is most likely valvular lesion associated with this infection?

A- Mitral valve stenosis
B- Mitral valve regurgitation
C- Tricuspid valve regurgitation
D- Aortic valve stenosis
E- Pulmonic valve stenosis

This patient most likely has infective endocarditis, a common complication of intravenous drug addiction. It is caused by staphylococcus infection due to multiple uses of same injection by addicts. Tricuspid regurgitation is the most common valvular lesion related to staph infection. It is characterized by pansystolic murmur, high pitched and loudest in the 4th intercostal space in the parasternal region. Mitral valve involvement is more likely related to subacute bacterial endocarditis which is mainly caused by streptococcal infection.
The correct answer is C

 

Question 5. A 48-year old man presents to the emergency room with severe headache and blurred vision. His blood pressure is 230/140. Ophthalmologic examination reveals blurred optic discs with indistinct margins. An intravenous drip of nitroprusside is started. What is the mechanism of action of this medication?

A- Alpha adrenergic antagonist
B- Beta adrenergic antagonist
C- Ganglion blocker
D- ACE inhibitor
E- Direct smooth muscle vasodilator

This is a case of hypertensive emergency and should be admitted to intensive care unit (ICU). Nitroprusside is the first line treatment in this condition. Nitroprusside is a direct smooth muscle vasodilator. It works directly on the large arteries to lower systolic blood pressure. This patient has to be continuously monitored to avoid sudden severe drop of blood pressure which can lead to ischemic injuries and death.
The correct answer is E

 

Question 6. A 62-year-old woman visits her physician for a routine physical examination. She has a long history of lower back pain and she takes ibuprofen as needed. She also takes levothyroxine for hypothyroidism. She exercises daily for 30 minutes and follows a regular diet. On examination, her pulse is 45/min. Holter monitor reveals a regular pulse ranging from 40-80 pulse/min. Her thyroid-stimulating hormone is within normal limits. What is the best management for this patient at this point?

A- Reassurance and follow up visits
B- Repeat Holter monitor examination
C- Perform exercise stress test
D- Pacemaker implantation
E- Refer to a cardiologist

This patient has sinus bradycardia with no symptoms. She exercises daily with no complaints. The best management at this point is reassurance and follow up visits to recheck for any new symptoms. Pacemaker is only implanted in case of symptomatic bradycardia.
The correct answer is A

 

Question 7. A 48-year-old man with a long history of type 1 diabetes and hypertension develops sudden chest pain and dizziness. On examination, pulse is 110, blood pressure is 80/50, no pulsus paradoxus, lungs are clear and jugular veins are dilated. ECG shows sinus tachycardia with ST elevation in leads II, III and AVF. What is the best next step of action?

A- IV fluids stat
B- IV heparin
C- Sublingual glyceryl nitrate (GTN)
D- IV dobutamine
E- IV calcium gluconate

This patient is in shock due to right ventricular infarction as a part of inferior MI diagnosed by clinical findings and ECG. Immediate IV fluids are crucial for this patient. GTN is contraindicated as it leads to dilation of blood vessels and worsening his hypotension. IV dobutamine is used if fluids failed to improve shock. Other options are not considered the best next step of action.
The correct answer is A

 

Question 8. A 22-year-old man presents to the emergency room complaining of sudden onset of shortness of breath and palpitation for 2 hours. He had similar episodes in the past which resolved by breath holding. His past medical, surgical and family histories are unremarkable. He takes no medication. ECG reveals supraventricular tachycardia. Carotid massage on the right side fails to stop the attack. What is the most likely next step in management?

A- Try carotid massage on the left side
B- IV procainamide
C- IV adenosine
D- IV succinylcholine
E- IV lidocaine

Paroxysmal supraventricular tachycardia is the most common arrhythmia with a rapid heart rate. If regular non-pharmacological procedures as breath holding, Valsalva maneuver or carotid massage fail, IV adenosine is the first drug of choice to reverse this attack.
The correct answer is C

 

Question 9. A 75-year-old man develops sudden onset of shortness of breath at the orthopedic department. He was admitted for suspected pathological fracture of femur 3 days ago. On examination, his pulse is 122, blood pressure 90/60, respiratory rate 34/min and oxygen saturation is 92%. Lung sounds are clear bilaterally. Heart rhythm is regular with no murmurs or gallops. What is the appropriate immediate step to improve this patient’s condition?

A- Intravenous injection of broad spectrum antibiotics
B- Intravenous injection of heparin
C- Subcutaneous injection of epinephrine
D- Electric cardioversion
E- Call the cardiology attendant

This is a case of pulmonary embolism characterized by dyspnea, hypotension and tachycardia. The age of the patient and the fracture are important risk factors. Immediate IV injection of heparin is mandatory on this situation and could be lifesaving.
The correct answer is B

 

Question 10. A 58-year-old man presents to the clinic with sudden weakness of his right arm. He also complains of progressive difficulty breathing on exertion, palpitations and a low grade fever during the last month. Examination reveals elevated jugular venous pressure, a loud S1 and mid-diastolic rumbling murmur heard at the apex. Transesophageal echocardiography (TEE) confirms the diagnosis. What is the most likely diagnosis?

A- Atrial thrombus
B- Atrial myxoma
C- Left ventricular wall aneurysm
D- Vegetative valvular lesions

This is most likely a case of atrial myxoma which causes a mid-diastolic murmur heard at the apex. Tumor causes low grade fever and neurologic deficits due to emboli. TEE is diagnostic. Atrial thrombus causes sudden dyspnea and palpitation and more progressive. Other options lead to different presentations.
The correct answer is B

 

High-yield points from this set

  • Mid-systolic click with a late systolic murmur that gets longer on standing = mitral valve prolapse.
  • Stable atrial fibrillation with a fast rate: rate control with a beta-blocker such as metoprolol.
  • Any adult with chest pain needs a 12-lead ECG and cardiac enzymes first.
  • IV drug use endocarditis most often affects the tricuspid valve.
  • Hypertensive emergency with papilledema: IV nitroprusside (direct arterial and venous vasodilator).
  • Asymptomatic sinus bradycardia in a fit person needs only reassurance.
  • Inferior MI with hypotension, clear lungs and distended neck veins = RV infarction: give IV fluids, avoid nitrates.
  • SVT not stopped by vagal maneuvers: IV adenosine.
  • Sudden dyspnea and hypotension after a fracture with clear lungs = pulmonary embolism: start heparin.
  • Mid-diastolic rumble, fever and embolic stroke = left atrial myxoma.

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