Red flags
- Acute breathlessness + chest pain - ACS, PE, dissection, tension pneumothorax
- Orthopnoea + PND + bibasal crackles + raised JVP - acute pulmonary oedema
- Sudden breathlessness + haemodynamic collapse - massive PE, tamponade, tension pneumothorax
- New murmur + breathlessness - acute valve failure (papillary muscle rupture, endocarditis)
- Breathlessness + hypotension + muffled heart sounds + raised JVP - tamponade (Beck's triad)
Differential by mechanism
Cardiac
- Acute decompensated heart failure (any cause - ischaemia, arrhythmia, valve disease, non-adherence)
- ACS (breathlessness as an anginal equivalent, especially in diabetics/elderly/women)
- Arrhythmia (fast AF, VT) causing reduced cardiac output
- Pericardial effusion/tamponade
- Acute severe valve lesion
Non-cardiac mimics - always keep on the list
- PE, pneumothorax, pneumonia, asthma/COPD exacerbation
- Anaemia, metabolic acidosis (compensatory tachypnoea), anxiety/hyperventilation
- Obesity, deconditioning
Focused history
- Onset (sudden vs gradual), exertional vs at rest, orthopnoea (pillows used), PND
- Associated chest pain, palpitations, cough/sputum/haemoptysis, fever, leg swelling
- Functional class (NYHA) and trajectory - useful both diagnostically and for monitoring known HF
- Known cardiac history, medication adherence, recent dietary/fluid indiscretion, recent medication changes (esp. NSAID, new negative inotrope)
- Risk factors for PE (immobility, malignancy, recent surgery, prior VTE)
Focused examination
- Vital signs including SpO2 and respiratory rate
- JVP - raised in cardiac causes
- Auscultation - bibasal crackles, S3, murmurs, wheeze (cardiac asthma can mimic bronchospasm)
- Peripheral oedema, hepatomegaly
- Signs of the non-cardiac mimics - calf swelling (PE), reduced air entry/hyperresonance (pneumothorax), consolidation (pneumonia)
Investigation strategy
First-line for all
- ECG - ischaemia, arrhythmia, prior infarct, low voltage/electrical alternans (effusion)
- CXR - pulmonary congestion, cardiomegaly, effusion, consolidation, pneumothorax
- BNP/NT-proBNP - useful negative predictive value to rule out cardiac cause when low; note confounders (obesity lowers, renal impairment/AF/age raise)
- FBE (anaemia), UEC, troponin if ACS possible
Directed further testing
- Echocardiogram - defines the cardiac mechanism (systolic/diastolic dysfunction, valve disease, effusion, RV strain)
- CTPA if PE likely
- ABG/VBG if severity assessment or acid-base contribution needed
Management
Acute decompensated heart failure
- Sit upright, oxygen if hypoxic, IV loop diuretic, IV nitrate if hypertensive and not hypotensive
- Non-invasive ventilation (CPAP) for significant respiratory distress/hypoxia unresponsive to initial therapy
- Identify and treat the precipitant - arrhythmia, ischaemia, infection, non-adherence, uncontrolled hypertension
- Once stable, optimise guideline-directed HF therapy (do not simply discharge on diuretic alone)
Other cardiac causes
- Tamponade - urgent pericardiocentesis
- Fast AF/VT causing breathlessness - rate/rhythm control or cardioversion per haemodynamic stability
- Acute valve failure - urgent cardiology/cardiothoracic referral
When the cause is non-cardiac
- Treat per the specific diagnosis (anticoagulation for PE, bronchodilators/steroids for exacerbation, antibiotics for pneumonia, transfusion for symptomatic anaemia)
Traps
- Treating "cardiac asthma" (wheeze from pulmonary oedema) with bronchodilators alone without recognising the underlying heart failure
- Relying on a single BNP without echo when the clinical picture is ambiguous
- Missing breathlessness as an anginal equivalent in diabetics, the elderly, and women who may not report classic chest pain
- Giving IV fluids reflexively to a breathless hypotensive patient without first excluding cardiogenic shock/tamponade
- Discharging decompensated HF on diuretics without addressing the precipitant or optimising background therapy
Talk track
1. Cardiac or not - JVP, BNP, and the CXR do most of the sorting
- "Raised JVP and congestion on CXR point strongly cardiac; a normal BNP argues against it."
2. Always ask what precipitated a decompensation
- "Arrhythmia, ischaemia, infection, non-adherence, or a new NSAID - treating the trigger prevents the next admission."
3. Acute pulmonary oedema has a specific bundle
- "Sit up, oxygen if hypoxic, IV diuretic, nitrate if the pressure allows, CPAP if they're still struggling."
4. Don't anchor on heart failure in a known HF patient
- "A known heart failure patient can still have a PE or pneumonia causing this episode."
5. Discharge planning means optimising therapy, not just clearing the fluid
- "Getting them dry is only half the job - GDMT optimisation is what keeps them out of hospital."
8 of 8 sections written · drafted 2026-09-13