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Cardiovascular

Heart Failure

HF High-yield Verified · Aug 2026

Heart failure is a clinical syndrome in which a structural or functional heart problem keeps the ventricles from filling with or ejecting enough blood to meet the body’s needs.

The single highest-yield cardiovascular disorder: it ties together preload and afterload, the RAAS, five drug classes, daily weights, and the classic decompensation scenario.

What’s going wrong in the body

The normal physiology, where it fails, and why the body’s compensation backfires.

01 A pump that can’t meet demand

Cardiac output is heart rate × stroke volume, and stroke volume depends on preload (how much blood fills the ventricle), afterload (the pressure it must pump against), and contractility (how forcefully it squeezes). Heart failure is any structural or functional problem that breaks this equation — the ventricle either can’t eject well or can’t fill well.

The ejection fraction (EF) tells you which problem dominates, and it drives both classification and treatment: HFrEF (reduced EF, ≤ 40%) is a weakened pump; HFpEF (preserved EF, ≥ 50%) is a stiff ventricle that resists filling; 41–49% is “mildly reduced.” A previously reduced EF that recovers above 40% is “improved” — the categories are a trajectory, not a life sentence.

02 The compensation that backfires

When cardiac output falls, the body responds exactly as it would to hemorrhage — and that is the tragedy of heart failure. The sympathetic nervous system fires: heart rate and contractility rise and vessels constrict. The kidneys, sensing poor perfusion, activate the renin–angiotensin–aldosterone system: angiotensin II constricts vessels further and directly drives myocardial hypertrophy and fibrosis, while aldosterone and vasopressin retain sodium and water.

Every arm of this response raises the failing heart’s workload: volume retention raises preload, vasoconstriction raises afterload, and catecholamines raise oxygen demand while chronically dulling the heart’s beta-receptor responsiveness. Overworked myocytes die and are replaced with fibrous tissue — remodeling — which drops output further and spins the cycle again. This vicious cycle is precisely why the mortality-reducing drugs are the ones that block compensation (ACE inhibitors, beta-blockers, aldosterone antagonists), not the ones that whip the heart harder.

The vicious cycle: compensation for low output raises the failing heart’s workload, which lowers output further.

03 Left-sided failure — blood backs into the lungs

When the left ventricle can’t empty, pressure backs up into the left atrium and the pulmonary veins behind it. Fluid is pushed out of pulmonary capillaries into the interstitium and alveoli — this is why left-sided failure is a breathing story: exertional dyspnea, a cough when lying down, crackles at the bases, and in florid decompensation, frothy or blood-tinged sputum.

Gravity explains the classic positional symptoms. Lying flat returns pooled venous blood from the legs to the chest, so congestion worsens within minutes (orthopnea — “how many pillows do you sleep on?”) or wakes the patient gasping after an hour or two (paroxysmal nocturnal dyspnea). An S3 gallop — blood tumbling into an overfilled, non-compliant ventricle — is one of the earliest and most significant exam findings.

04 Right-sided failure — blood backs into the body

The right ventricle pumps into the lungs, so when it fails, blood dams up in the systemic veins: distended neck veins (JVD), a congested tender liver, ascites, anorexia and nausea from bowel-wall edema, and dependent pitting edema in the ankles — or the sacrum of a bedbound patient.

The most common cause of right-sided failure is left-sided failure: chronically elevated pulmonary pressures become the afterload the right ventricle must fight until it, too, gives out. That is why most real patients present with a mixed picture — and why total-body fluid, tracked as daily weight, is the single most useful bedside number.

Backward failure: the left side congests the lungs; sustained lung pressure then breaks the right side, which congests the body.

Causes & risk factors

Modifiable factors are teaching targets — the patient can act on them.

Coronary artery disease / prior MI (leading cause) Hypertension modifiable Diabetes & metabolic syndrome modifiable Obesity modifiable Smoking modifiable Excess alcohol modifiable Valvular heart disease Cardiomyopathies & myocarditis Atrial fibrillation Thyroid disease Cardiotoxic drugs (e.g. some chemotherapy)

Signs & symptoms

Each finding tied to the mechanism that produces it — and the triage it calls for.

Dyspnea on exertion early Expected
Why: Congested lungs stiffen and gas exchange falls just as activity raises oxygen demand — usually the earliest complaint.
Fatigue & activity intolerance early Expected
Why: Low cardiac output shortchanges skeletal muscle; the body is perfusing core organs first.
S3 gallop early
Why: Blood decelerating into an overfilled, poorly compliant ventricle — one of the most significant and early exam findings of HF.
Orthopnea — needs pillows to sleep Hold & notify
Why: Lying flat returns pooled leg blood to the chest, sharply raising pulmonary congestion — one of the most specific HF symptoms (~89%). Ask "how many pillows?" — a rising number means worsening failure.
Paroxysmal nocturnal dyspnea Hold & notify
Why: Slow overnight redistribution of interstitial fluid into the circulation floods the lungs 1–2 hours into sleep — the patient wakes gasping.
Crackles (rales) at lung bases · recumbent cough Hold & notify
Why: Fluid transudated into alveoli pops open on inspiration; new or ascending crackles mean congestion is climbing.
Weight gain > 2–3 lb in a day or 5 lb in a week Hold & notify
Why: Overnight weight change is retained fluid, not fat — the earliest objective sign of decompensation and the reason daily weights are non-negotiable.
Jugular venous distention (JVD)
Why: Systemic venous pressure from a failing right heart is visible in the neck; hepatojugular reflux (sustained JVP rise > 4 cm) confirms it.
Dependent pitting edema (ankles; sacrum if bedbound) Expected
Why: Elevated venous pressure pushes fluid into the tissues wherever gravity pools it.
Hepatomegaly, early satiety, anorexia & nausea late
Why: The congested liver stretches its capsule and edematous bowel absorbs poorly — an underrecognized cause of weight loss and cachexia in advanced HF.
Nocturia Expected
Why: Lying down finally perfuses the kidneys well, so urine output rises at night — fragmenting sleep.
Pink, frothy sputum with severe breathlessness late Report immediately
Why: Alveoli flooding with protein-rich fluid — acute pulmonary edema, not "bad congestion." Sit the patient up and get help now.
New confusion or falling mental status late Report immediately
Why: The brain is losing perfusion — a low-output warning sign, and one of the findings that must be reported immediately.

Diagnostics

Test In this disorder Normal
BNP / NT-proBNP Runs high with renal failure, ACS, and age; low with obesity — trend the individual patient rather than comparing across patients Elevated, tracking severity. In acute dyspnea, BNP < 100 pg/mL or NT-proBNP < 300 pg/mL makes HF unlikely — the rule-out numbers to know StatPearls BNP < 100 pg/mL
Echocardiogram (LVEF) Initial modality of choice; also shows structure, wall motion, valves The defining test — ≤ 40% = HFrEF · 41–49% = mildly reduced · ≥ 50% = HFpEF AHA/ACC/HFSA 2022 —
Chest X-ray A clear film does not exclude HF Enlarged cardiac silhouette, basal edema, vascular congestion, Kerley B lines —
Electrolytes & renal function Trend with every diuretic or RAAS-blocker change K⁺ and creatinine move with treatment — diuretics waste potassium; ACE inhibitors/ARBs and MRAs retain it; creatinine rises in cardiorenal syndrome —
ECG May show prior infarction, chamber enlargement, conduction delay, or the atrial fibrillation that decompensated the patient —

Complications

Warning: Acute decompensation → pulmonary edema Report immediately
Sudden severe dyspnea, anxiety, crackles throughout, pink frothy sputum, plummeting SpO₂.
The nurse’s first moves are positional and fast: high-Fowler’s with legs dependent (drops preload), oxygen per protocol, rapid-acting IV diuretics as ordered, and an immediate provider/rapid-response call. Minutes matter.
Warning: Cardiogenic shock Report immediately
Pump failure so severe the organs hypoperfuse: falling BP, cool clammy skin, dropping urine output, confusion.
The end-stage of the vicious cycle — the compensations have nothing left to squeeze. Managed in critical care with inotropes and vasopressors (see the vasopressors class page).
Warning: Arrhythmias & sudden cardiac death Report immediately
Stretched, scarred myocardium is electrically unstable; atrial fibrillation is common and ventricular arrhythmias can kill.
This is why an ICD is offered for primary prevention at LVEF ≤ 35% (NYHA II–III) — and why any new irregular, very fast, or very slow rhythm gets reported.
Caution: Cardiorenal syndrome Hold & notify
The underperfused, venously congested kidney fails alongside the heart: creatinine climbs, urine output falls despite diuretics.
Falling urine output despite diuretic therapy is a report-now finding — it signals the treatment window is closing.
Caution: Thromboembolism
Blood pooling in dilated, poorly contracting chambers forms mural thrombi that can embolize to brain, kidneys, lungs, or limbs.
Part of why coexisting atrial fibrillation usually means anticoagulation.

Medications for this condition

Why each class is prescribed here — every card links to its full pharmacology page.

ACE Inhibitors First-line
Cardiovascular · lisinopril

Pillar 1 (RAS inhibition): blocks the angiotensin II arm of the vicious cycle — less vasoconstriction, less remodeling, proven mortality benefit. Guidelines now prefer an ARNI (sacubitril/valsartan) first-line; an ACE inhibitor or ARB fills the pillar when an ARNI can’t be used.
ARBs
Cardiovascular · losartan

The RAS-inhibition pillar for patients who can’t tolerate an ACE inhibitor (classically because of cough).
Beta-Blockers First-line
Cardiovascular · metoprolol

Pillar 2: blunts the sympathetic arm of the compensation cycle. Only three are evidence-based in HFrEF — carvedilol, bisoprolol, metoprolol succinate — started low and titrated slowly.
Potassium-Sparing Diuretics First-line
Renal · spironolactone

Pillar 3: the mineralocorticoid receptor antagonists (spironolactone, eplerenone) block aldosterone — less sodium retention and less fibrosis. Watch potassium.
Oral Antidiabetics First-line
Endocrine · metformin

Pillar 4: SGLT2 inhibitors reduce HF mortality and hospitalization whether or not the patient has diabetes — the newest pillar of guideline-directed therapy.
Loop Diuretics
Renal · furosemide

The congestion reliever: clears the volume overload behind the dyspnea and edema. Improves symptoms, not mortality — and wastes potassium, so pair every dose with the K⁺ trend.
Cardiac Glycosides (Digoxin) High-alert
Cardiovascular · digoxin

Digoxin: an add-on for persistent symptoms in HFrEF in sinus rhythm — helps symptoms and hospitalization, not survival. Narrow therapeutic index; know the toxicity picture.
Nitrates
Cardiovascular · nitroglycerin

Hydralazine + isosorbide dinitrate: the vasodilator combination with proven benefit in African American patients with NYHA III–IV HFrEF on guideline therapy.

Beyond medications

  • Sodium restriction — commonly 1,500–2,300 mg/day in patient instructions; the exact limit is provider-set. Fluid restriction (≈ 2 L/day) when prescribed.
  • Daily weight self-monitoring — same scale, every morning, after voiding, before breakfast; keep a written log.
  • Device therapy for selected HFrEF: ICD for primary prevention (LVEF ≤ 35%, NYHA II–III); CRT when the QRS is wide (≥ 150 ms, LBBB) at LVEF ≤ 35%.
  • Activity & rehab — regular tolerated activity and cardiac rehabilitation; deconditioning worsens symptoms.
  • Risk-factor work — smoking cessation, alcohol reduction, weight management, tight BP and glucose control.

Nursing considerations

The RN-specific layer — each action paired with the reason it matters.

Assessment & monitoring
Weigh daily — same scale, same time (morning, after voiding, before breakfast), similar clothing — and trend it.
Why: Overnight weight change is fluid, not fat. A 2–3 lb jump is the earliest objective sign of decompensation, days before crackles appear.
Keep strict intake & output; flag urine output that falls despite diuretics.
Why: Diuretic resistance with falling output signals cardiorenal decline — one of the report-immediately findings.
Auscultate lungs and heart each shift: track crackle height and listen for an S3.
Why: Ascending crackles chart the congestion rising; a new S3 is an early, significant sign of an overfilled ventricle.
Monitor rate, rhythm and SpO₂; report new irregularity, sustained tachycardia, or falling saturation.
Why: Remodeled myocardium is arrhythmia-prone, and uncontrolled tachycardia or hypoxia are report-now findings.
Track K⁺ and creatinine with every diuretic or RAAS-blocker change.
Why: Loop diuretics waste potassium while ACE inhibitors and MRAs retain it — the patient sits between two opposite electrolyte risks.
Treat any new confusion or lethargy as a perfusion problem until proven otherwise.
Why: Mental-status change in HF means the brain is not being perfused — a low-output red flag, not "just tiredness."
During an exacerbation
Sit the patient in high-Fowler’s (head of bed 60–90°) with legs dependent; apply oxygen per protocol.
Why: Upright positioning drops venous return (preload), maximizes chest expansion, and frees the diaphragm — the fastest preload reduction available without a drug.
Give IV diuretics as ordered and measure the response: urine output, weight, breath sounds, SpO₂.
Why: The response — not the dose — is the outcome; it steers the next order.
Cluster care and schedule rest between activities.
Why: Every exertion spends a limited cardiac output; pacing prevents demand from outrunning supply.
Fall precautions: orthostatic checks, assistance up, night lighting.
Why: Diuretics, vasodilators, beta-blockers and nocturia combine into a high fall risk.
Patient teaching (the discharge difference)
Call the provider for weight gain > 2–3 lb in a day or 5 lb in a week, worsening breathlessness, orthopnea (more pillows), new cough, or swelling.
Why: Patients who self-monitor catch decompensation days early — the difference between a med adjustment and a readmission.
Keep sodium within the prescribed limit (typically 1,500–2,300 mg/day); read labels — most salt is already in the food.
Why: Sodium holds water; every gram of it works directly against the diuretic.
Take the ACE inhibitor, beta-blocker, MRA and SGLT2 inhibitor even when feeling well — never stop them without the provider.
Why: These drugs extend life by blocking the compensation cycle, not by relieving symptoms — "feeling fine" is them working, not a reason to stop.
Take diuretics at the same time each morning — never right before bed.
Why: An evening dose trades sleep for bathroom trips; a consistent morning routine keeps diuresis predictable and adherence realistic.
Avoid NSAIDs, watch for infections, and never skip doses — the classic exacerbation triggers.
Why: Recent infection, missed medications, NSAID use, and salt binges are the most common precipitants of acute decompensation.
Stay as active as tolerated; use energy-conservation pacing rather than bed rest.
Why: Deconditioning shrinks the very reserve the failing heart depends on.

How a real nurse thinks

The clinical-judgment loop, worked for a typical presentation — reasoning, not reference.

  1. 1
    Recognize cues

    The cues that matter: 3 lb overnight weight gain, new orthopnea (recliner), RR 24 with SpO₂ 90%, bibasilar crackles, new cough — and a K⁺ of 3.3 on a loop diuretic. The mildly elevated BP and normal temperature are background noise here.

  2. 2
    Analyze cues

    The weight, orthopnea, crackles and hypoxia all point one direction: pulmonary congestion is worsening despite IV diuretics — decompensating left-sided failure. The hypokalemia is a second, separate problem: it is the furosemide working on the wrong ion, and it makes an already arrhythmia-prone heart more irritable.

  3. 3
    Prioritize

    Airway–breathing first: the SpO₂ of 90% with rising work of breathing outranks everything. The potassium is urgent but not before oxygenation. Sequence: position → oxygen → provider notification (congestion + K⁺ together) → medication decisions.

  4. 4
    Generate solutions

    Raise the head of bed to high-Fowler’s with legs dependent; apply O₂ per protocol; call the provider with a single SBAR covering both problems — anticipate potassium replacement and a diuretic/med review; keep strict I&O; recheck the weight to confirm.

  5. 5
    Take action

    Position and oxygenate immediately (no order needed to sit a patient up). Deliver the SBAR: *"3 lb overnight gain, new orthopnea, bibasilar crackles, SpO₂ 90% RA on IV furosemide — and this morning’s K⁺ is 3.3. Requesting evaluation, anticipate K⁺ replacement; please confirm you want the 0800 furosemide and cardiac meds given as scheduled."* Giving more loop diuretic on a K⁺ of 3.3 without replacement is the trap — clarify first, don’t independently hold the regimen.

  6. 6
    Evaluate

    Success looks like: SpO₂ recovering on the ordered oxygen, respiratory rate falling, urine output responding, tomorrow’s weight down, crackles receding, and a rechecked K⁺ back in range. No improvement — or any rhythm change — re-escalates immediately.

Scenario — you’re the nurse

Work each question before revealing the answer. Rationales explain the wrong options too.

Med-surg unit · 0715, just after handoff

A 68-year-old man admitted 2 days ago with a heart failure exacerbation. History: MI 3 years ago, HFrEF (LVEF 30%), hypertension. Orders include IV furosemide twice daily; home carvedilol and lisinopril are continued. Overnight report: "slept in the recliner — said he couldn’t breathe lying down. New dry cough."

0700 vitals — HR 102 · BP 148/88 · RR 24 · SpO₂ 90% on room air · T 37.0 °C
0600 weight — 84.2 kg (yesterday 82.8 kg → +1.4 kg / ~3 lb overnight)
Assessment — crackles at both bases; +2 pitting edema to ankles; alert and oriented
0600 labs — K⁺ 3.3 mEq/L · creatinine 1.1 mg/dL · BNP elevated
Due at 0800 — carvedilol, lisinopril, IV furosemide
Q1 Select all that apply
After handoff, which findings require follow-up? Select all that apply.
  1. A. Weight up 1.4 kg (~3 lb) since yesterday
  2. B. Blood pressure 148/88 mmHg
  3. C. Slept in the recliner because he "couldn’t breathe lying down"
  4. D. Temperature 37.0 °C
  5. E. Potassium 3.3 mEq/L
Reveal answer & rationale
Answer: A, C, E
The overnight weight jump is retained fluid — the earliest objective decompensation sign. New orthopnea means pulmonary congestion is rising. K⁺ 3.3 is below range on a potassium-wasting diuretic and raises arrhythmia risk. The BP is mildly elevated but stable and chronic (B), and 37.0 °C is normal (D) — neither demands action this morning.
Q2 Multiple choice
The weight gain, new orthopnea, bibasilar crackles and SpO₂ of 90% together most likely indicate:
  1. A. Expected findings for a patient receiving IV diuretics
  2. B. Worsening pulmonary congestion — the exacerbation is decompensating despite treatment
  3. C. A new pneumonia
  4. D. Anxiety-related hyperventilation
Reveal answer & rationale
Answer: B
The pattern — fluid weight + positional dyspnea + basal crackles + hypoxia — is the left-sided congestion story worsening despite therapy (B). On effective diuresis you expect weight *down* and breathing *easier*, so (A) is backwards. Pneumonia (C) typically brings fever and focal findings — his temp is 37.0 °C. Hyperventilation (D) doesn’t cause weight gain or crackles.
Q3 Put in order
Put the nurse’s first four actions in priority order:
  1. A. Notify the provider (SBAR: worsening congestion + K⁺ 3.3)
  2. B. Raise the head of bed to high-Fowler’s, legs dependent
  3. C. Apply oxygen per unit protocol
  4. D. Document assessment findings and continue routine care
Reveal answer & rationale
Correct order: B → C → A → D
Position first — it drops preload and eases breathing instantly and needs no order. Oxygen next for the SpO₂ of 90%. Then the SBAR call combining both problems. Documentation matters but never precedes stabilizing the patient. Calling before positioning (A first) leaves the patient hypoxic while you’re on the phone.
Q4 Multiple choice
IV furosemide is due at 0800 and this morning’s K⁺ is 3.3 mEq/L. The best nursing action is:
  1. A. Give the furosemide as scheduled — diuresis is the priority in an exacerbation
  2. B. Hold all 0800 medications until the provider rounds
  3. C. Notify the provider of the K⁺ before the dose and anticipate potassium replacement
  4. D. Encourage high-potassium foods and give the furosemide
Reveal answer & rationale
Answer: C
Furosemide wastes potassium, and 3.3 is already low — more diuresis without replacement invites arrhythmia, so the provider needs the lab before the dose (C). Giving it blindly (A) ignores the lab; dietary potassium (D) is far too slow to cover an IV diuretic. Holding *everything* (B) is also wrong — abruptly stopping the beta-blocker and ACE inhibitor removes the very drugs blocking the compensation cycle; the decision belongs to the provider, informed by your SBAR.
Q5 Multiple choice
Which finding on tomorrow’s 0600 assessment best indicates the interventions are working?
  1. A. The patient says he feels less anxious
  2. B. Weight down 1.1 kg with crackles now faint at the bases and SpO₂ 94% on room air
  3. C. Blood pressure decreased to 138/84 mmHg
  4. D. The patient slept through the night without voiding
Reveal answer & rationale
Answer: B
Effective decongestion shows up as the objective trio: weight down, lungs clearing, oxygenation recovering (B). Feeling calmer (A) and a modestly lower BP (C) are pleasant but nonspecific. Not voiding all night on IV diuretics (D) is the *opposite* of success — falling urine output despite diuretics is a report-immediately finding.

Common questions

What causes heart failure?
Common causes and risk factors include coronary artery disease / prior mi (leading cause), hypertension, diabetes & metabolic syndrome, obesity, smoking, and others.
What are the early signs of heart failure?
Early findings include Dyspnea on exertion, Fatigue & activity intolerance, S3 gallop.
Which findings should a nurse report immediately in heart failure?
Report immediately: Pink, frothy sputum with severe breathlessness, New confusion or falling mental status, Acute decompensation → pulmonary edema, Cardiogenic shock, Arrhythmias & sudden cardiac death. These signal deterioration that needs rapid intervention.
Which medications are used to treat heart failure?
Commonly prescribed drug classes include ACE Inhibitors, ARBs, Beta-Blockers, Potassium-Sparing Diuretics, Oral Antidiabetics, and others — each is covered in depth in the pharmacology course.
What is the difference between HFrEF and HFpEF?
Both are heart failure, but HFrEF (ejection fraction ≤ 40%) is a weak pump that can’t eject, while HFpEF (EF ≥ 50%) is a stiff ventricle that can’t fill. The four-pillar mortality drugs are proven in HFrEF; HFpEF management leans on the SGLT2 inhibitor, diuretics for congestion, and treating the causes (hypertension, AF).
What commonly triggers a heart failure exacerbation?
The classic precipitants are recent infection, missed medications, NSAID use, and increased salt intake. When a previously stable patient decompensates, ask about all four.

Sources

Reviewed by Hae Suk Lee, RN

Educational summary for nursing students. Scenarios are fictional teaching cases. Always verify against current guidelines and your institution's protocols before acting in practice. Not medical advice.