What are the signs and symptoms of left-sided heart failure?

Left-sided heart failure causes fluid to back up into the lungs, producing pulmonary symptoms. Key signs include dyspnea on exertion, orthopnea which is difficulty breathing when lying flat, paroxysmal nocturnal dyspnea where the patient wakes at night gasping for air, crackles or rales on lung auscultation, cough with frothy pink-tinged sputum in severe cases, fatigue, tachycardia, and S3 heart sound also called a ventricular gallop. Chest X-ray shows pulmonary congestion.