Heart failure

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Heart failure

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USMLE® Step 1 style questions USMLE

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 76-year-old woman presents to the emergency department for evaluation of increased lower extremity swelling and shortness of breath. The patient has had progressive lower extremity swelling over the past several weeks to the point where she can no longer fit into her normal shoe size. In addition, she can no longer walk half a city block before becoming short of breath. Past medical history includes hypertension, diabetes, and a deep vein thrombosis after a long flight ten years ago. The patient has been smoking one pack of cigarettes per day for thirty-five years. Temperature is 36.1°C (97.0°F), pulse is 78/min, respirations are 16/min, blood pressure is 156/92 mmHg, and O2 is 90% on room air. Physical examination demonstrates a loud P2, jugular venous distension, faint bilateral end-expiratory wheezing, and 2+ pitting edema in the bilateral lower extremities. A chest X-ray is obtained and shown below. Which of the following best describes the pathophysiology of this patient’s lower extremity findings?  


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ACE inhibitors p. 628

heart failure p. 316

Angiotensin II receptor blockers p. 628

heart failure p. 316

β -blockers p. 245

heart failure p. 316

Cardiomyopathy p. 315

heart failure with p. 316

Diastole

heart failure and p. 316

Diuretics

heart failure p. 316

Dyspnea

heart failure p. 316

Edema

heart failure and p. 316

Fatigue

heart failure and p. 316

Heart failure p. 316

ACE inhibitors for p. 628

acromegaly p. 341

acute tubular necrosis with p. 620

amiodarone p. 327

angiotensin II receptor blockers p. 628

aortic regurgitation as precursor p. 296

associations p. 733

atrial septal defect p. 303

β -blockers for p. 245, 327

B-type natriuretic peptide in p. 299

calcium channel blockers p. 361

carcinoid syndrome p. 586

cardiac glycosides for p. NaN

chronic ischemic heart disease p. 308

contractility in p. 290

diabetic ketoacidosis p. 355

disopyramide p. 326

dobutamine for p. 241

dopamine for p. 241

Ebstein anomaly p. 302

ejection fraction in p. 290

ESR in p. 210

fludrocortisone and p. 360

hydralazine for p. 320

hypertension p. 304

hypertension treatment in p. 320

hypertensive emergency and p. 304

jugular venous pulse in p. 293

loop diuretics for p. 624

MI p. 309

Paget disease of bone p. 468

pleural effusion p. 699

potassium-sparing diuretics p. 627

pulmonary hypertension p. 697

pulse pressure in p. 290

readmissions with p. 276

renal failure causing p. 620

shock caused by p. 320

in sleep apnea p. 697

systolic vs diastolic p. 290

thiazides for p. 627

ventricular septal defect p. 303

Hydralazine p. 323

heart failure p. 316

Hypertension p. 304

heart failure p. 320

Loop diuretics p. 624

for heart failure p. 316

Myocardial infarction (MI) p. 308

heart failure caused by p. 316

Peripheral edema

heart failure p. 316

Pulmonary edema

heart failure p. 316

Spironolactone p. 627, 663, 673, 676

for heart failure p. 316

Thiazide diuretics

heart failure p. 316

Transcript

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Content Reviewers

Heart failure’s used to describe 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.

Congestive heart failure affects millions of people around the world and since it means that the body’s needs are not being met, it can ultimately lead to death.

Part of the reason why so many people are affected by heart failure, is that there are a wide variety of heart diseases like ischemia and valvular disease that can impair the heart’s ability to pump out blood and—over time—can ultimately cause the heart to fail.

Alright, first up is systolic heart failure, kind of a mathematical way to think this one is that the heart needs to squeeze out a certain volume of blood each minute, called cardiac output, which can be rephrased as the heart rate (or the number of beats in a minute) multiplied by the stroke volume (the volume of blood squeezed out with each heart beat).

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

For example, in an adult the heart might beat 70 times per minute and the the left ventricle might squeeze out 70ml per beat, so 70 x 70 equals a cardiac output of 4900 ml per minute, which is almost 5 liters per minute.

So notice that not all the blood was pumped out right?

And the stroke volume is only a fraction of the total volume.

The total volume might be closer to 110 ml, and 70ml is the fraction that got ejected out with each beat, the other 40ml kind of lingers in the left ventricle until the next beat, right?

In this example, the ejection fraction would be 70ml divided by 110 ml or about 64%, a normal ejection fraction is around 50-70%, between 40-50% would be considered borderline, and anything about 40% or less would indicate systolic heart failure because the heart is only squeezing out a little blood each beat.

Sources

  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. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "The Impact of Frailty and Comorbidities on Heart Failure Outcomes" Cardiac Failure Review (2022)
  6. "Effects of Digoxin in Heart Failure (HF) With Reduced Ejection Fraction (EF)" Cureus (2022)
  7. "Advanced heart failure: guideline‐directed medical therapy, diuretics, inotropes, and palliative care" ESC Heart Failure (2022)
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