Cardiac cycle Practice Questions

Question 1

A 75-year-old man presents to the emergency department after an episode of syncope while walking outside with his wife. His wife states that he suddenly appeared pale and collapsed to the ground. She says he remained unconscious for 1 minute. He says he noticed a fluttering in his chest and excessive sweating before the episode. He has type 2 diabetes mellitus, essential hypertension, and chronic stable angina. He has not started any new medications in the past few months. Vital signs reveal: temperature 37.0°C (98.6°F), blood pressure 135/72 mm Hg, and pulse 72/min. Physical examination is unremarkable. ECG shows an old bifascicular block. Echocardiogram and 24-hour Holter monitoring are normal. Which of the following is the best next step in the evaluation of this patient's condition?

Accepted Answer

Continuous loop recorder

Answer

Cardiac enzymes

Answer

Valsalva maneuver

Answer

Electroencephalography (EEG)

Answer

Tilt-table test

Question 2

A 62-year-old man comes to the physician for decreased exercise tolerance. Over the past four months, he has noticed progressively worsening shortness of breath while walking his dog. He also becomes short of breath when lying in bed at night. His temperature is 36.4°C (97.5°F), pulse is 82/min, respirations are 19/min, and blood pressure is 155/53 mm Hg. Cardiac examination shows a high-pitch, decrescendo murmur that occurs immediately after S2 and is heard best along the left sternal border. There is an S3 gallop. Carotid pulses are strong. Which of the following is the most likely diagnosis?

Accepted Answer

Aortic valve regurgitation

Answer

Tricuspid valve regurgitation

Answer

Mitral valve prolapse

Answer

Mitral valve regurgitation

Answer

Mitral valve stenosis

Question 3

During exercise, what is the primary mechanism for increased oxygen delivery to active muscles?

Accepted Answer

Increased cardiac output

Answer

Decreased blood viscosity

Answer

Increased hemoglobin affinity

Answer

Enhanced oxygen diffusion

Question 4

A 27-year-old man presents to the clinic for his annual physical examination. He was diagnosed with a rare arrhythmia a couple of years ago following an episode of dizziness. A mutation in the gene encoding for the L-type calcium channel protein was identified by genetic testing. He feels fine today. His vitals include: blood pressure 122/89 mm Hg, pulse 90/min, respiratory rate 14/min, and temperature 36.7°C (98.0°F). The cardiac examination is unremarkable. The patient has been conducting some internet research on how the heart works and specifically asks you about his own “ventricular action potential”. Which of the following would you expect to see in this patient?

Accepted Answer

Abnormal phase 2

Answer

Abnormal phase 4

Answer

Abnormal phase 0

Answer

Abnormal phase 3

Answer

Abnormal phase 1

Question 5

A 60-year-old male engineer who complains of shortness of breath when walking a few blocks undergoes a cardiac stress test because of concern for coronary artery disease. During the test he asks his cardiologist about what variables are usually used to quantify the functioning of the heart. He learns that one of these variables is stroke volume. Which of the following scenarios would be most likely to lead to a decrease in stroke volume?

Accepted Answer

Heart failure

Answer

Anxiety

Answer

Exercise

Answer

Pregnancy

Answer

Digitalis

Question 6

A 70-year-old Caucasian male visits your office regularly for treatment of New York Heart association class IV congestive heart failure. Which of the following medications would you add to this man's drug regimen in order to improve his overall survival?

Accepted Answer

Spironolactone

Answer

Furosemide

Answer

Amiloride

Answer

Acetazolamide

Answer

Hydrochlorothiazide

Question 7

A 21-year-old man presents to his physician for a routine checkup. His doctor asks him if he has had any particular concerns since his last visit and if he has taken any new medications. He says that he has not been ill over the past year, except for one episode of the flu. He has been training excessively for his intercollege football tournament, which is supposed to be a huge event. His blood pressure is 110/70 mm Hg, pulse is 69/min, and respirations are 17/min. He has a heart sound coinciding with the rapid filling of the ventricles and no murmurs. He does not have any other significant physical findings. Which of the following best describes the heart sound heard in this patient?

Accepted Answer

Third heart sound (S3)

Answer

Fourth heart sound (S4)

Answer

Opening snap

Answer

Second heart sound (S2)

Answer

Mid-systolic click

Question 8

You are interested in studying the etiology of heart failure reduced ejection fraction (HFrEF) and attempt to construct an appropriate design study. Specifically, you wish to look for potential causality between dietary glucose consumption and HFrEF. Which of the following study designs would allow you to assess for and determine this causality?

Accepted Answer

Cohort study

Answer

Cross-sectional study

Answer

Case series

Answer

Case-control study

Answer

Randomized controlled trial

Question 9

An 83-year-old male presents with dyspnea, orthopnea, and a chest radiograph demonstrating pulmonary edema. A diagnosis of congestive heart failure is considered. The following clinical measurements are obtained: 100 bpm heart rate, 0.2 mL O2/mL systemic blood arterial oxygen content, 0.1 mL O2/mL pulmonary arterial oxygen content, and 400 mL O2/min oxygen consumption. Using the above information, which of the following values represents this patient's cardiac stroke volume?

Accepted Answer

40 mL/beat

Answer

30 mL/beat

Answer

70 mL/beat

Answer

60 mL/beat

Answer

50 mL/beat

Question 10

A 73-year-old woman presents to clinic with a week of fatigue, headache, and swelling of her ankles bilaterally. She reports that she can no longer go on her daily walk around her neighborhood without stopping frequently to catch her breath. At night she gets short of breath and has found that she can only sleep well in her recliner. Her past medical history is significant for hypertension and a myocardial infarction three years ago for which she had a stent placed. She is currently on hydrochlorothiazide, aspirin, and clopidogrel. She smoked 1 pack per day for 30 years before quitting 10 years ago and socially drinks around 1 drink per month. She denies any illicit drug use. Her temperature is 99.0°F (37.2°C), pulse is 115/min, respirations are 18/min, and blood pressure is 108/78 mmHg. On physical exam there is marked elevations of her neck veins, bilateral pitting edema in the lower extremities, and a 3/6 holosystolic ejection murmur over the right sternal border. Echocardiography shows the following findings:

End systolic volume (ESV): 100 mL
End diastolic volume (EDV): 160 mL

How would cardiac output be determined in this patient?

Accepted Answer

(160 - 100) * 115

Answer

108/3 + (2 * 78)/3

Answer

(160 - 100) / 160

Answer

160 - 100

Answer

(100 - 160) * 115

Cardiac cycle

Study Resources

Lessons

Questions

Flashcards

Lessons

Phases of the cardiac cycle

Pressure-volume relationships

Heart sounds and their origin

Ventricular filling dynamics

Valve function during cardiac cycle

Electrical-mechanical coupling

Isovolumetric contraction and relaxation

Ventricular ejection physiology

Atrial contribution to cardiac function

Cardiac cycle in pathologic states

Diastolic function assessment

Systolic function assessment

Effects of heart rate on cardiac cycle

Practice Questions

Flashcards

About Cardiac cycle for USMLE

Lessons in Cardiac cycle

Master Cardiac cycle