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USMLE Step 1Cardiovascular physiologyEP 09 of 16

HFrEF vs HFpEF on the pressure-volume loop

HFrEF vs HFpEF comes down to which curve moves: a flatter ESPVR breaks emptying, a steeper EDPVR breaks filling. Both raise end-diastolic pressure and can congest the lungs.

  • 5:33 video
  • 3 min read
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  • Published 9 Nov 2026
Video lesson · 5:33 · Watch on YouTubeSeries: Pressure–Volume Loops & Cardiac Physiology · @medservatory
Chapters (8)
By the end of this lesson

Contrast the mechanisms of heart failure with reduced versus preserved ejection fraction using ESPVR and EDPVR changes on the pressure–volume loop.

The short version

  1. HFrEF is a problem of emptying: the ESPVR flattens, the loop shifts right, and the ejection fraction is 40% or less.
  2. HFpEF is a problem of filling: the EDPVR steepens (up and to the left), end-diastolic volume is normal or low, and the ejection fraction is 50% or more.
  3. Ejection fraction is stroke volume divided by end-diastolic volume, so in HFpEF it can look normal because both shrink together.
  4. An ejection fraction of 41–49% is mildly reduced.
  5. Both types raise end-diastolic pressure, which backs up through the left atrium into the lungs and can cause breathlessness.

HFrEF vs HFpEF: same symptoms, different curves

Two patients climb one flight of stairs and stop, breathless, with swollen ankles. One has an ejection fraction of 35%; the other, 62%. Both have heart failure.

HFrEF vs HFpEF is answered on the pressure–volume loop by asking which of two curves has moved: the ESPVR or the EDPVR.[1][4]

The two curves and the ejection fraction

  • ESPVR (end-systolic pressure–volume relationship): the highest pressure the ventricle can generate at each volume. Its slope tracks contractility.[1]
  • EDPVR (end-diastolic pressure–volume relationship): the filling pressure at each volume. Steeper means stiffer.[1]
Ejection fraction
EF = stroke volume / end-diastolic volume

Stroke volume = EDV − ESV.[1]

Normal ventricle (teaching model)
  1. EDV 120 mL, ESV 50 mL
  2. SV = 120 − 50 = 70 mL
  3. EF = 70 / 120 ≈ 58%

HFrEF on the pressure-volume loop: the ESPVR flattens

An infarct or a dilated cardiomyopathy costs the ventricle muscle. Contractility falls, so the ESPVR flattens.[1][2]

End-systolic volume rises: less blood leaves and more is left behind. The next beat fills on top of that leftover, so end-diastolic volume rises too, and so does end-diastolic pressure. Over months, remodelling shifts the whole loop to the right.[1][2]

HFrEF in the teaching model
  1. EDV about 170 mL, ESV about 125 mL
  2. SV = 170 − 125 = 45 mL
  3. EF = 45 / 170 ≈ 26%
  4. End-diastolic pressure about 25 mm Hg

The problem is emptying, and the ejection fraction is 40% or less.[4]

HFpEF on the pressure-volume loop: the EDPVR steepens

Now the same breathlessness, but the muscle squeezes well. Years of high blood pressure can thicken and stiffen the wall (hypertrophy and fibrosis), which steepens the EDPVR and shifts it up and to the left. The ESPVR is not the main problem.[1][3]

Filling now costs far more pressure. In our teaching model, to reach 105 mL the stiff ventricle needs about 25 mm Hg, where a normal one needs about 7. End-diastolic volume ends up a little low, and stroke volume falls to about 60 mL. The direction of each change is supported by[1][3]; the numbers are illustrative.

HFpEF in the teaching model
  1. EDV 105 mL, SV about 60 mL
  2. EF = 60 / 105 ≈ 57%
  3. EF stays normal because SV and EDV shrank together

The problem is filling, and the ejection fraction is 50% or more.[4]

Ejection fraction cut-offs and the shared congestion

HFrEF vs HFpEF at a glance
HFrEFHFpEF
ProblemEmptyingFilling
Curve that movesESPVR flatter; loop shifts rightEDPVR steeper, up and to the left
End-diastolic volumeRaisedNormal or low (105 vs 120 mL in the model)
Ejection fraction40% or less50% or more
End-diastolic pressureHighHigh

An ejection fraction of 41–49% is mildly reduced (heart failure with mildly reduced EF).[4]

Both types share a high end-diastolic pressure. It backs up through the left atrium into the lungs, which is the breathlessness.[1]

Practice question

Original · USMLE style
Your turnQB-MS-S1-CARD-009-01

A 68-year-old woman has had hypertension for 20 years. She reports exertional dyspnea, orthopnea and leg edema. Echocardiography shows a thick-walled, small left ventricle with normal valves. Cardiac catheterization shows:

Results
LV end-diastolic volume82 mL
LV end-systolic volume28 mL
LV end-diastolic pressure30 mm Hg
Compared with a normal ventricle, which of the following combinations best describes her left ventricular pressure-volume relationships?
Pick one option. Your answers stay on this device.

Common questions

What is the difference between HFrEF and HFpEF?

HFrEF is a problem of emptying: the ESPVR flattens and the ejection fraction is 40% or less. HFpEF is a problem of filling: the EDPVR steepens and the ejection fraction is 50% or more.

What does ESPVR measure?

The highest pressure the ventricle can generate at each volume. Its slope tracks contractility.

What does a steeper EDPVR mean?

A stiffer ventricle: more pressure is needed to reach any given filling volume.

Why can the ejection fraction be normal in HFpEF?

Ejection fraction is stroke volume divided by end-diastolic volume. In HFpEF both shrink together, so the ratio changes very little.

What ejection fraction is mildly reduced?

41–49%, between HFrEF (40% or less) and HFpEF (50% or more).

Transcript

Read the full narration, by chapter615 words

0:00Two breathless patients, one diagnosis

Two patients climb one flight of stairs and stop, breathless, with swollen ankles. One has an ejection fraction of 35%. The other, 62%. Both have heart failure. How? By the end of this lesson, you'll contrast HF r EF and HF p EF by what moves on the pressure–volume loop: the ESPVR, or the EDPVR.

0:26The two curves: ESPVR and EDPVR, and EF = SV / EDV

The ESPVR, top left, is the highest pressure the ventricle can generate at each volume. Its slope tracks contractility. The EDPVR, bottom right, is the filling pressure at each volume. Steeper means stiffer. And ejection fraction is just stroke volume divided by end-diastolic volume. Our normal ventricle: end-diastolic volume 120 mL, end-systolic volume 50, stroke volume 70, ejection fraction 58%.

1:00HFrEF: the ESPVR flattens

First, the ESPVR. An infarct, or a dilated cardiomyopathy, has cost the ventricle muscle. Contractility falls, so the ESPVR flattens. End-systolic volume rises. Less blood leaves, and more is left behind. The next beat fills on top of that leftover, so end-diastolic volume rises too, and so does end-diastolic pressure. In our model: end-diastolic volume about 170 mL, end-systolic volume about 125, stroke volume 45, ejection fraction about 26%, and end-diastolic pressure about 25 millimetres of mercury. Over months, remodelling shifts the whole loop to the right. That is HF r EF. The problem is emptying, and the ejection fraction is 40% or less.

1:58HFpEF: the EDPVR steepens

Now the other curve. Same breathlessness, but this time the muscle squeezes well. Years of high blood pressure thicken and stiffen the wall. That steepens the EDPVR, shifting it up and to the left. The ESPVR is not the main problem. But filling now costs far more pressure. To reach 105 mL, our stiff ventricle needs about 25 millimetres of mercury, where a normal one needs about seven. So end-diastolic volume ends up a little low, and stroke volume falls to about 60. Ejection fraction? Sixty over 105: about 57%. Normal, because stroke volume and end-diastolic volume shrank together. That is HF p EF. The problem is filling, and the ejection fraction is 50% or more.

2:55EF cut-offs and the shared congestion

In between, 41 to 49, is mildly reduced. Both share a high end-diastolic pressure. It backs up through the left atrium into the lungs: the breathlessness.

3:08Practice question

Your turn. Pause to work it out. A 68-year-old woman has 20 years of hypertension, exertional dyspnea, orthopnea and leg edema. Echo shows a thick-walled, small left ventricle. Catheterization: end-diastolic volume 82 mL, end-systolic volume 28, and left ventricular end-diastolic pressure 30 mm Hg. Compared with normal, which combination best describes her pressure–volume relationships? A: flatter ESPVR, EDPVR shifted right. B: flatter ESPVR, EDPVR shifted up and left. C: ESPVR unchanged, EDPVR shifted down and right. D: ESPVR unchanged, EDPVR shifted up and left. E: steeper ESPVR, EDPVR unchanged.

4:13Answer: wrong options first

Stroke volume is 54, so the ejection fraction is about 66%: preserved. A is out: a flatter ESPVR means a low ejection fraction. B is out for the same reason. C is out: down and right means more compliance, so a low filling pressure. E is out: an unchanged EDPVR at 82 mL would give a low pressure, not 30. The answer is D. A good ejection fraction means the ESPVR is not the problem, and a high pressure at a small volume means a stiff EDPVR shifted up and to the left.

4:55Recap and next lesson

Quick recap. One: HF r EF is a flatter ESPVR. The loop shifts right, and the ejection fraction is 40% or less. Two: HF p EF is a stiffer EDPVR. Filling pressure rises, volume is small, and the ejection fraction is 50% or more. Three: both raise end-diastolic pressure, so both cause pulmonary congestion. Next, we leave the heart and follow the pressure into the vessels: blood pressure, resistance and Poiseuille's law.

Sources

Numbers in the text, e.g. [1], point here
  1. Klabunde RE. CV Physiology: Pathophysiology of Heart Failure (hf003); Ventricular Systolic Dysfunction (HFrEF) (hf005); Ventricular Diastolic Dysfunction (HFpEF) (hf006); Combined Systolic and Diastolic Dysfunction (hf007); Pulmonary Capillary Wedge Pressure (hf008); Ventricular Pressure-Volume Relationship (cf024). cvphysiology.com/heart-failure/hf003 · cvphysiology.com/heart-failure/hf005 · cvphysiology.com/heart-failure/hf006 · cvphysiology.com/heart-failure/hf007 · cvphysiology.com/heart-failure/hf008 · cvphysiology.com/cardiac-function/cf024
  2. Bastos MB et al. Invasive left ventricle pressure–volume analysis. Eur Heart J 2020;41(12):1286–1297. pmc.ncbi.nlm.nih.gov/articles/PMC7084193/
  3. Omote K, Verbrugge FH, Borlaug BA. Heart failure with preserved ejection fraction: mechanisms and treatment strategies. Annu Rev Med 2022. pmc.ncbi.nlm.nih.gov/articles/PMC9002335
  4. American College of Cardiology. Ten Points to Remember: 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure (EF categories). acc.org/latest-in-cardiology/ten-points-to-remember/2022/03/29/19/53/2022-aha-acc-hfsa-heart-failure-guideline-gl-hf

The practice question is original and its patient is synthetic. Every fact is checked against the sources above in independent accuracy reviews. Always follow your local guidelines and your own laboratory’s ranges.

Image credits. Illustrations: Servier Medical Art (smart.servier.com), CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/), adapted (recoloured, outlined): systolic heart failure, diastolic heart failure, cardiac hypertrophy, pulmonary edema. Pressure–volume loops, charts, number line and all handwriting are drawn in code (original). Previous: Cardiac Output and the Fick Principle · Next: Blood Pressure, Resistance and Poiseuille's Law

Corrections. None so far. Spotted an error? Email info@medservatory.com with the lesson code MS-S1-CARD-009.

For exam study only, not medical advice. Read the medical disclaimer.

In this series

Playlist on YouTube
← Previous · EP 08Fick principle: how to calculate cardiac output
  1. EP 01Pressure-volume loop explained: four phases, four valve events5:00
  2. EP 02Preload on the pressure-volume loop: EDV, stroke volume and the EDPVR5:04
  3. EP 03Afterload on the pressure-volume loop4:49
  4. EP 04Contractility on the pressure-volume loop: the ESPVR explained5:17
  5. EP 05Wiggers diagram explained: the cardiac cycle step by step5:30
  6. EP 06The Frank-Starling curve: preload, inotropy and heart failure4:44
  7. EP 07Aortic stenosis vs mitral regurgitation on the pressure-volume loop5:41
  8. EP 08Fick principle: how to calculate cardiac output5:07
  9. EP 09HFrEF vs HFpEF on the pressure-volume loop5:33
  10. EP 10Poiseuille's law and vascular resistance: why arterioles matter5:15
  11. EP 11Venous return and cardiac function curves: where they cross5:11
  12. EP 12The baroreceptor reflex: from stretch to vagal and sympathetic output5:17
  13. EP 13Myocardial oxygen supply and demand: why tachycardia causes ischaemia4:50
  14. EP 14Unstable angina vs NSTEMI vs STEMI: from plaque to ACS4:50
  15. EP 15Antianginal drugs: nitrates, beta blockers, calcium channel blockers4:56
  16. EP 16Complications of myocardial infarction, by timeline4:59