Heart failure

1. THE 2-MINUTE PHYSIOLOGY (Rapid Pathophysiology)

Acute heart failure (AHF) is a clinical syndrome driven by elevated intracardiac pressures and/or depressed cardiac output due to structural or functional cardiovascular abnormalities. It represents a sudden, life-threatening imbalance between myocardial oxygen supply and demand, frequently precipitating acute respiratory failure.

For the emergency provider, AHF is classically divided into two distinct pathophysiological phenotypes:

• The Vascular Phenotype (Sympathetic Crashing Acute Pulmonary Edema): Characterized by a dramatic, abrupt onset (<1 week) driven by severe hypertension and massive sympathetic overdrive. This causes profound systemic vasoconstriction (increased afterload), forcing a rapid redistribution of fluid from the venous beds into the pulmonary circulation, causing "flash" alveolar edema without significant total body fluid overload.
• The Cardiac Phenotype (Gradual Fluid Accumulation): Driven by progressive pump failure, leading to a gradual accumulation of total body fluid, systemic venous congestion, and peripheral edema over days to weeks.

2. THE BEDSIDE ACTION PLAN (Rapid ER Management)

• Immediate Stabilization & Airway: Place the patient upright. If the patient has severe dyspnea or pulmonary edema, immediately initiate Noninvasive Positive Pressure Ventilation (NIPPV, e.g., BiPAP or CPAP). NIPPV rapidly decreases the work of breathing, decreases venous return (preload), and decreases left ventricular afterload, frequently avoiding the need for endotracheal intubation.
• Hemodynamic Management (Vascular Phenotype/Hypertensive):
• Target a ~25% reduction in systolic blood pressure (SBP).
• Nitroglycerin: Start with 0.4 mg sublingual x 1–5 doses, then rapidly transition to a high-dose continuous IV nitroglycerin infusion to achieve profound venodilation and arterial afterload reduction.
• Diuretics: Administer an IV loop diuretic (e.g., Furosemide 20–40 mg IV, or 1 to 2.5 times the patient's home oral daily dose).
• Hemodynamic Management (Cardiogenic Shock/SBP < 90 mm Hg):
• Strictly avoid vasodilators and aggressive IV fluid boluses if pulmonary congestion is present.
• Initiate Norepinephrine as the first-line vasopressor.
• Add an inotrope like Dobutamine (or Milrinone if the patient is chronically on beta-blockers) to improve forward flow.

3. THE DIAGNOSTIC GRID (Differential Diagnosis & Workup)

• "Can't-Miss" Differential Diagnoses:
• Acute Coronary Syndrome (ACS): A primary trigger for new-onset AHF and cardiogenic shock.
• Pulmonary Embolism (PE): Can mimic heart failure with dyspnea, hypoxia, and right heart strain.
• Aortic Dissection: Can cause acute aortic regurgitation and heart failure.
• COPD/Asthma Exacerbation: Wheezing can occur in AHF ("cardiac asthma") and perfectly mimic primary pulmonary disease.
• Prioritized Diagnostic Workup:
• Natriuretic Peptides: BNP or NT-proBNP. A BNP < 100 pg/mL effectively rules out AHF, while > 500 pg/mL strongly rules it in. NT-proBNP utilizes age-adjusted cutoffs (> 450 pg/mL for < 50 yrs; > 900 for 50–75 yrs; > 1800 for > 75 yrs).
• Cardiac Biomarkers: Serial high-sensitivity troponins are mandatory to rule out ACS as the precipitating cause.
• Comprehensive Panel: CBC, basic metabolic panel (evaluate for cardiorenal syndrome via BUN/Creatinine), electrolytes, and TSH.

4. THE VISUAL BOARD (ECG / POCUS / Imaging)

• Point-of-Care Ultrasound (POCUS - The Gold Standard):
• Lung Ultrasound (LUS): Perform an 8-point exam. The presence of $\ge$3 B-lines (hyperechoic stripes extending > 15 cm from the pleura, erasing A-lines) in at least 2 of 4 lung zones per hemithorax is highly specific for AHF.
• Cardiac/IVC: Look for a hypokinetic/dilated left ventricle (reduced EF) and a plethoric inferior vena cava (IVC > 2 cm with < 50% inspiratory collapse) indicating severe venous congestion.
• 12-Lead ECG: Look for STEMI, dynamic ischemic ST-T wave changes, new Left Bundle Branch Block (LBBB), or dysrhythmias (e.g., rapid Atrial Fibrillation) that could precipitate the failure.
• Chest Radiography (CXR): Look for cardiomegaly, pleural effusions, interstitial edema, cephalization of vessels, and Kerley B lines.

5. THE SCORING MATRIX (Risk Stratification & Guidelines)

• Validated Tools: The Ottawa Heart Failure Risk Scale and the MEESSI-AHF Score are utilized to predict 7-to-30 day mortality and guide disposition.
• High/Moderate Risk (Admit to ICU/Step-down): Cardiogenic shock, respiratory failure, hemodynamically unstable arrhythmias, concurrent ACS, requirement of IV vasodilators in the ED, persistent hypoxia, elevated troponin, or new renal/hepatic dysfunction. De novo AHF (first-time presentation) must be admitted for comprehensive evaluation.
• Low Risk (Consider ED Discharge): SBP > 160 mm Hg without hypertensive emergency, few comorbidities, normal troponin, unchanged renal/hepatic function, high diuretic efficiency in the ED, symptom resolution, and guaranteed outpatient follow-up in $\le$ 7 days.

6. THE DANGER ZONE (Pitfalls & Critical Actions)

• Cognitive Trap (The "Cardiac Asthma" Misdirection): Misdiagnosing AHF as a COPD or asthma exacerbation because the patient is wheezing. Auscultated wheezing is highly common in AHF and is neither sensitive nor specific enough to differentiate the two clinically without POCUS.
• Cognitive Trap (The Fluid Bolus Reflex): Reflexively administering a 30 mL/kg crystalloid fluid bolus to a hypotensive patient. If the patient is in cardiogenic shock with pulmonary edema, IV fluids will catastrophically worsen respiratory failure.
• Cognitive Trap (Inotropes for Everyone): Initiating inotropes (e.g., dobutamine) in AHF patients who have low blood pressure but lack signs of true cardiogenic shock. Routine use of inotropes outside of true shock increases mortality.
• Critical Action: Recognize the vascular, sympathetically driven phenotype early and aggressively treat the afterload (hypertension) with high-dose IV nitrates to prevent intubation.

7. MCQ MASTERCLASS (Written Exam Tips)

• Buzzwords: "B-lines" (pulmonary edema on ultrasound), "De novo AHF" (requires admission), "Kerley B lines", "Orthopnea" (dyspnea in recumbent position).
• Classic Distractor (The Hypotensive Resuscitation): A patient presents with crushing chest pain, BP 72/50, and diffuse rales. The distractor option will suggest "Bolus 30 mL/kg of crystalloid fluid." Explanation: This is cardiogenic shock with pulmonary edema. Fluids are contraindicated. The correct answer is to initiate Norepinephrine.
• Classic Distractor (The Beta-Blocked Patient): A patient on chronic metoprolol presents in cardiogenic shock. A distractor will offer "Initiate Dobutamine." Explanation: Beta-blocked patients will not respond adequately to a beta-agonist like dobutamine. You must select Milrinone (a phosphodiesterase-3 inhibitor).

8. THE BOARDROOM SCRIPT (OSCE & Oral Board Tips)

• The Initial Approach: "This patient is presenting in severe respiratory distress with hypoxia and hypertension, highly concerning for acute heart failure—specifically the vascular, sympathetically driven phenotype. I will immediately place the patient upright, apply continuous cardiac monitors, and initiate Noninvasive Positive Pressure Ventilation (BiPAP) to decrease the work of breathing, preload, and afterload."
• Executing the Resuscitation: "To rapidly identify the etiology, I am performing an 8-point bedside lung ultrasound to look for diagnostic B-lines, and a cardiac echo to assess the ejection fraction and IVC. Because their blood pressure is significantly elevated, I am ordering sublingual nitroglycerin followed immediately by a continuous IV nitroglycerin infusion, targeting a 25% reduction in systolic blood pressure, along with IV Furosemide."
• Diagnostic Closure & Disposition: "I am ordering a 12-lead ECG and serial high-sensitivity troponins to rule out acute coronary syndrome as the precipitant, alongside an NT-proBNP and basic metabolic panel. Given the requirement for IV vasodilators and NIPPV in the ED, this patient has high-risk features and will require admission to a step-down or intensive care unit."