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CONGESTIVE HEART FAILURE (CHF)

A Complete Exam-Oriented Clinical Teaching Guide

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1. DEFINITION

Exam tip: "Congestive" = fluid congestion from backup pressure. The heart fails forward (low output) AND backward (raised venous pressure).

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2. CAUSES (ETIOLOGY)

Common Causes

Important Risk Factors

• Hypertension (single most prevalent risk factor)
• Coronary artery disease / prior MI
• Diabetes mellitus
• Obesity
• Atrial fibrillation
• Valvular heart disease
• Alcohol abuse (alcoholic cardiomyopathy)
• Chemotherapy (anthracyclines - doxorubicin)
• Family history / genetic cardiomyopathy
• Sleep apnea

High-output failure (rare but examinable)

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3. TYPES / CLASSIFICATION

A. By Ejection Fraction (Most Clinically Used)

Key point: Normal EF is >60%. HFpEF is increasingly common, especially in elderly hypertensive women.

B. By Side of Failure

C. By Onset

• Acute HF - sudden onset (e.g., flash pulmonary edema after MI)
• Chronic HF - gradual onset with compensation

D. NYHA Functional Classification (Exam Favorite)

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4. PATHOPHYSIOLOGY

Step-by-Step Flowchart

Simplified Pathophysiology Flowchart

INITIAL MYOCARDIAL INJURY (MI, HTN, cardiomyopathy)
                ↓
    ↓ Cardiac Output (CO)
          ↙              ↘
↓ Carotid sinus          ↓ Renal blood flow
   firing                     ↓
      ↓                  ↑ Renin → ↑ Angiotensin II
↑ Sympathetic                  ↓
  discharge              ↑ Aldosterone → Na+ & H2O retention
      ↓                        ↓
↑ HR, ↑ Contractility    ↑ Preload (fluid overload)
↑ Vasoconstriction →                ↓
↑ Afterload                 Pulmonary & Systemic Congestion
                                     ↓
                     FURTHER ↓ in CO (vicious cycle)
                                     ↓
              Cardiac REMODELING (hypertrophy → dilation)
                                     ↓
               Myocyte apoptosis → Worsening failure

Why the Compensation Fails:

1. Sympathetic overstimulation → Beta-1 receptor downregulation → reduced response + arrhythmias
2. Angiotensin II → vasoconstriction + aldosterone release → more fluid retention = worse congestion
3. Cardiac hypertrophy → initially helps, but capillary density doesn't increase proportionally → ischemia of hypertrophied muscle → fibrosis → reduced function
4. Ventricular remodeling → pathological dilation → mitral regurgitation from papillary muscle displacement → further worsens function

Morphological Changes (Robbins Pathology):

• Left heart failure: LV hypertrophy + dilation, LA dilation, pulmonary edema, "heart failure cells" (hemosiderin-laden macrophages) in lungs
• Right heart failure: RV hypertrophy + dilation, hepatomegaly (nutmeg liver), peripheral edema, ascites, pleural effusions

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5. CLINICAL FEATURES

Left-Sided Heart Failure (Pulmonary Congestion)

• Tachycardia (compensatory)
• Displaced apex beat (cardiomegaly)
• S3 gallop (volume overload, most specific sign of systolic HF)
• S4 gallop (stiff ventricle, diastolic HF)
• Functional mitral regurgitation murmur (pansystolic)
• Bilateral basal crackles (fine, crepitations) - don't clear with coughing
• Cheyne-Stokes respiration (in severe HF)

Right-Sided Heart Failure (Systemic Venous Congestion)

Biventricular HF: All of the above combined

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6. KEY SYMPTOMS THAT SUGGEST THE DIAGNOSIS

Hallmark Symptom

Classic Clinical Triad (Exam):

1. Dyspnea (exertional, then at rest)
2. Orthopnea (needs 2-3 pillows to sleep)
3. Bilateral ankle edema

Classic Clinical Clues

• History of MI / HTN / valve disease
• S3 gallop on auscultation (most specific physical sign)
• Raised JVP + bilateral crackles + ankle edema = classic presentation
• Displaced apex beat (cardiomegaly)
• Hepatojugular reflux (HJR) - pressing on liver raises JVP

Red Flag Findings (Acute Decompensation)

• Pink frothy sputum = acute pulmonary edema (emergency!)
• SpO2 <90% on room air
• Resting tachycardia >120 bpm
• BP drop (cardiogenic shock)
• Altered mental status (cerebral hypoperfusion)
• Oliguria/anuria (renal failure from reduced perfusion)

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7. LABORATORY INVESTIGATIONS

Exam Pearl: BNP is the single most important blood test to order when CHF is suspected. It distinguishes cardiac dyspnea (high BNP) from pulmonary dyspnea (low/normal BNP).

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8. DIFFERENTIAL DIAGNOSIS

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9. SHORT CLINICAL CASES

Case 1 - Acute Decompensated Left HF

• Paroxysmal nocturnal dyspnea (woke at 2 AM) + orthopnea (3 pillows) = classic left HF
• Bilateral crackles + S3 = pulmonary congestion + volume overload
• CXR "bat-wing" = acute pulmonary edema
• BNP markedly elevated confirms cardiac cause
• Hypertension + prior MI = known risk factors and likely precipitant

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Case 2 - Right-Sided HF / Cor Pulmonale

• Heavy smoker + hyperinflated lungs = COPD
• COPD → pulmonary hypertension → RV strain → RV failure
• JVD + hepatomegaly + pitting edema = classic right HF triad
• No pulmonary edema / crackles = not primarily left-sided
• Elevated RVSP on echo confirms pulmonary hypertension

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10. TREATMENT

A. Non-Pharmacological Treatment

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B. Pharmacological Treatment

Treatment Summary by Stage

1. Sit patient upright + high-flow oxygen
2. IV Furosemide 40-80 mg stat
3. IV/sublingual Nitrates (reduces preload)
4. IV Morphine 2-4 mg (with caution)
5. Non-invasive ventilation (CPAP/BiPAP) if SpO2 <90%
6. If hypotensive + shock → IV Dobutamine/Norepinephrine

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11. CLINICAL PEARLS

• S3 gallop = "Ken-tuc-KY" rhythm = most specific auscultatory finding of systolic HF (volume overload). S4 = "TEN-nes-see" = diastolic dysfunction.
• BNP is synthesized in ventricular myocytes in response to wall stretch. It is a marker of wall stress, not just fluid.
• Never start a beta-blocker in acutely decompensated ("wet") HF - wait until the patient is "dry" (euvolemic). But never stop a beta-blocker in a CHF patient unless in cardiogenic shock.
• The CXR triad of HF: Cardiomegaly (CTR >0.5) + Kerley B lines (interstitial edema) + Cephalization of pulmonary vessels
• "Heart failure cells" = hemosiderin-laden alveolar macrophages = pathological sign of repeated pulmonary edema episodes
• Digoxin toxicity is worsened by hypokalemia (both compete at Na+/K+ATPase); always check potassium before giving digoxin
• SGLT2 inhibitors (dapagliflozin, empagliflozin) are now the 4th pillar of HFrEF treatment alongside ACE-i/ARNI + BB + MRA (2022 ESC Guidelines)
• ACE inhibitor causes DRY COUGH (bradykinin); ARBs do NOT (no bradykinin)
• Sacubitril/Valsartan MUST NOT be started within 36 hours of ACE inhibitor use (risk of angioedema)
• Spironolactone causes gynecomastia → switch to eplerenone

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12. COMMON DIAGNOSTIC MISTAKES

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13. 5-MINUTE REVISION SUMMARY

DEFINITION:
Heart unable to pump blood to meet body's demands → forward failure (low output)
+ backward failure (venous congestion)
           ↓
CAUSES:
IHD/MI (most common) → HTN → Valvular disease → Dilated CMP → Myocarditis → AF
           ↓
PATHOPHYSIOLOGY:
↓CO → ↑Sympathetic + ↑RAAS → ↑HR + ↑Preload + ↑Afterload + Remodeling
→ Vicious cycle → Cardiac hypertrophy → Fibrosis → Apoptosis → Worsening failure
           ↓
SYMPTOMS:
Left HF: DOE → Orthopnea → PND → Pink frothy sputum
Right HF: JVD, Pitting edema, Hepatomegaly, Ascites
Signs: S3 gallop, displaced apex, bilateral crackles, raised JVP
           ↓
INVESTIGATIONS:
BNP >400 (diagnostic) | Echo (gold standard - EF, wall motion)
CXR (cardiomegaly + Kerley B + bat-wing) | ECG (AF, LVH, Q waves)
K+, Na+, Creatinine, TFT | Troponin (if ACS suspected)
           ↓
TREATMENT (HFrEF - 4 pillars):
1. ACE-i or ARNI (Sacubitril/Valsartan) - anti-remodeling
2. Beta-blocker (Carvedilol/Bisoprolol) - anti-arrhythmic
3. MRA (Spironolactone) - anti-fibrotic
4. SGLT2-i (Dapagliflozin) - cardioprotective
+ Diuretics (Furosemide) for symptom relief
Acute: O2 + IV Furosemide + IV Nitrates + CPAP
           ↓
COMPLICATIONS:
Arrhythmias (AF, VF) → Sudden cardiac death
Cardiogenic shock | Pulmonary edema | Renal failure (Cardiorenal syndrome)
Liver failure (Cardiac cirrhosis) | Stroke (AF + LV thrombus)
Cachexia (cardiac cachexia - poor prognosis sign)

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Recent Evidence Update (PubMed 2025): A meta-analysis published in Circulation (PMID: 40884036, Berg DD et al., Nov 2025 - DAPA ACT HF-TIMI 68 trial) confirmed that dapagliflozin initiated in-hospital for acute heart failure reduces the composite of worsening HF or CV death at 30 days. SGLT2 inhibitors are now supported for initiation even in the acute/hospitalized setting, not just stable outpatients.

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