Heart failure: Pathology review

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Heart failure: Pathology review




Heart failure: Pathology review

USMLE® Step 1 questions

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USMLE® Step 1 style questions USMLE

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A 74-year-old woman presents to her primary care physician for evaluation of shortness of breath. Over the past several weeks, the patient has been using three to four pillows to prop herself up to sleep at night. Past medical history includes hypertension, diabetes, hyperlipidemia, and myocardial infarction with stent placement. Temperature is 37.0°C (98.6°F), pulse is 78/min, respirations are 18/min, blood pressure is 148/82 mmHg, and O2 saturation is 97% on room air. Physical examination demonstrates an additional low frequency heart sound heard just after S2. Which of the following best describes the underlying pathophysiology of this cardiac finding?  


On the cardiology ward, there were two people who had been admitted to the hospital repeatedly.

The first one is 70 year old Lidia, who had a myocardial infarction about 3 years ago.

She presents with fatigue, and dyspnea.

She says that she usually wakes up at night because of shortness of breath, but using more pillows when sleeping helps relieve it somewhat.

On examination, she has pitting edema in her legs and on auscultation, an S3 sound is heard.

The other person is 81 year old Richard who has been a smoker for the past 50 years.

He is also experiencing fatigue, and has pitting edema, but on further examination, there’s also jugular venous distention and hepatomegaly.

Okay, so, both these individuals suffer from heart failure.

Heart failure is a clinical syndrome used to describe the inability of the heart to pump enough blood or a point at which the heart can’t supply enough blood to meet the body’s demands.

This can happen in two ways, either the heart’s ventricles can’t pump blood hard enough during systole, called systolic heart failure, or not enough blood fills into the ventricles during diastole, called diastolic heart failure.

In both cases, blood backs up into the lungs, causing congestion or fluid buildup, which is why it’s also often known as congestive heart failure, or just CHF.

Alright, first up is systolic heart failure.

One way to think about this is that the heart needs to squeeze out a certain volume of blood each minute, called cardiac output, which can be calculated as the heart rate multiplied by the stroke volume.

The heart rate is pretty intuitive, but the stroke volume is a little tricky.


  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Heart failure" Lancet (2005)
  4. "Evaluation and Management of Right-Sided Heart Failure: A Scientific Statement From the American Heart Association" Circulation (2018)
  5. "2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines" J Am Coll Cardiol (2013)

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