Cardiac output determinants — MCQs

A 25-year-old male athlete undergoes a cardiopulmonary exercise test. As exercise intensity increases from rest to moderate levels, which of the following best describes the relationship between oxygen consumption and cardiac output?

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

A 45-year-old unconscious man is brought to the emergency department by a friend who witnessed him collapse. They were working in a greenhouse spraying the vegetables when the man started to complain of blurred vision and nausea. On the way to the hospital, the man lost consciousness and lost bladder continence. The patient’s vital signs are as follows: blood pressure 95/60 mm Hg; heart rate 59/min; respiratory rate 22/min; and temperature 36.0℃ (96.8℉). On examination, he is unconscious with a GCS score of 7. His pupils are contracted and react poorly to light. Lung auscultation reveals diffuse wheezing. Cardiac auscultation is significant for bradycardia. Abdominal auscultation reveals increased bowel sounds. A cardiac monitor shows bradycardia with grade 2 AV-block. Which of the following leads to the cardiac manifestations seen in this patient?

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?

Which factor most strongly influences coronary blood flow during exercise?

A 70-year-old male presents for an annual exam. His past medical history is notable for shortness of breath when he sleeps, and upon exertion. Recently he has experienced dyspnea and lower extremity edema that seems to be worsening. Both of these symptoms have resolved since he was started on several medications and instructed to weigh himself daily. Which of the following is most likely a component of his medical management?

Which neurotransmitter is primarily responsible for parasympathetic effects on heart rate?

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?

A 34-year-old male is brought to the emergency department by fire and rescue following a motor vehicle accident in which the patient was an unrestrained driver. The paramedics report that the patient was struck from behind by a drunk driver. He was mentating well at the scene but complained of pain in his abdomen. The patient has no known past medical history. In the trauma bay, his temperature is 98.9°F (37.2°C), blood pressure is 86/51 mmHg, pulse is 138/min, and respirations are 18/min. The patient is somnolent but arousable to voice and pain. His lungs are clear to auscultation bilaterally. He is diffusely tender to palpation on abdominal exam with bruising over the left upper abdomen. His distal pulses are thready, and capillary refill is delayed bilaterally. Two large-bore peripheral intravenous lines are placed to bolus him with intravenous 0.9% saline. Chest radiograph shows multiple left lower rib fractures. Which of the following parameters is most likely to be seen in this patient?

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?