Left-Sided Heart Failure
Pathophysiology & Risk Factors
Left-sided heart failure means the left ventricle cannot move blood forward, so blood backs up into the lungs and produces pulmonary congestion. Two distinct subtypes drive it: systolic dysfunction (HFrEF), where the ventricle cannot squeeze (EF ≤ 40%), and diastolic dysfunction (HFpEF), where a stiff hypertrophied ventricle cannot relax and fill (EF ≥ 50%). Both raise left atrial and pulmonary capillary pressure, so both present with the same lung symptoms.
Subtype Compare
Systolic (HFrEF) vs Diastolic (HFpEF)
Systolic (HFrEF)
- Core defect
- Impaired contraction (can't squeeze)
- Ejection fraction
- Reduced ≤ 40%
- Typical patient
- Post-MI, dilated cardiomyopathy
- Gallop sound
- S3 (volume overload)
Diastolic (HFpEF)
- Core defect
- Impaired relaxation/filling (can't relax)
- Ejection fraction
- Preserved ≥ 50%
- Typical patient
- Elderly, chronic HTN, stiff hypertrophied ventricle
- Gallop sound
- S4 (stiff ventricle)
Signs & Symptoms
Diagnostics & Labs
Diagnostic
Monitor
Interventions & Priorities
Treatments & Medications
Patient Teaching
Clinical Pearl
LEFT = Lung congestion. Systolic can't SQUEEZE (EF ≤ 40%, S3); diastolic can't RELAX (EF ≥ 50%, S4) — only the echo EF tells them apart, not BNP.