left-sided heart failure
Summary
Left-sided heart failure occurs when the left ventricle fails to pump blood effectively, leading to pulmonary congestion (due to backup into pulmonary circulation) and/or reduced systemic perfusion. It presents classically with dyspnea, orthopnea, paroxysmal nocturnal dyspnea, and pulmonary edema. Causes include ischemic heart disease, hypertension, and valvular disease.
Detail
Left-sided heart failure is classified into two main types based on ejection fraction: heart failure with reduced ejection fraction (HFrEF, systolic dysfunction, EF <40%) and heart failure with preserved ejection fraction (HFpEF, diastolic dysfunction, EF ≥50%). In HFrEF, impaired contractility (e.g., from MI, dilated cardiomyopathy) reduces stroke volume, activating compensatory neurohormonal mechanisms (RAAS, sympathetic activation) that initially help but ultimately worsen remodeling. In HFpEF, impaired ventricular relaxation/compliance (e.g., from hypertension, restrictive/hypertrophic cardiomyopathy) elevates filling pressures despite normal EF.
Pathophysiology: Left ventricular dysfunction increases left ventricular end-diastolic pressure, which backs up into the left atrium and pulmonary veins, causing pulmonary venous congestion, transudation of fluid into alveoli (pulmonary edema), and symptoms of dyspnea, orthopnea, and paroxysmal nocturnal dyspnea. Chronic pulmonary congestion can lead to pulmonary hypertension and secondary right-sided heart failure (cor pulmonale from left heart disease).
Key exam findings: S3 gallop (volume overload), S4 (stiff ventricle in HFpEF), bibasilar crackles, pulmonary edema on CXR (Kerley B lines, bat-wing pattern, cephalization of vessels), laterally displaced PMI (in dilated LV), and cool extremities/hypotension in severe forward failure.
Etiologies: Ischemic heart disease/MI, chronic hypertension, dilated/hypertrophic/restrictive cardiomyopathies, valvular disease (aortic stenosis/regurgitation, mitral regurgitation), myocarditis.
Diagnosis: Elevated BNP/NT-proBNP, echocardiography to assess EF and wall motion, chest X-ray showing pulmonary edema, and clinical exam.
Management: Diuretics for symptom relief, ACE inhibitors/ARBs, beta-blockers, and mineralocorticoid receptor antagonists for HFrEF (mortality benefit); SGLT2 inhibitors now used in both HFrEF and HFpEF. Treat underlying cause (revascularization, BP control, valve repair/replacement).
High-yield board point: Distinguish left-sided failure (pulmonary symptoms: dyspnea, orthopnea, crackles) from right-sided failure (systemic symptoms: peripheral edema, JVD, hepatomegaly, ascites). Left-sided failure is the most common cause of right-sided heart failure.
Sources
- First Aid for the USMLE Step 1
- Pathoma - Fundamentals of Pathology (Husain)
- Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine
- UpToDate: Heart Failure Pathophysiology and Diagnosis
Reviewed by AnkiBoss editorial — medical student review. Information here is for study reference only and is not medical advice. Spotted an error? Let us know.