Pulmonary embolism occurs when a blood vessel in the lung is suddenly obstructed, disrupting blood flow and oxygen exchange. This can manifest as acute shortness of breath, palpitations, cough, and occasionally hemoptysis (bloody sputum). When a major pulmonary artery is affected, patients may experience severe chest pressure and syncope (fainting). If the clot is located in a vessel near the chest wall, a pleuritic chest pain may develop, often described as a sharp, stabbing sensation exacerbated by deep inspiration. In the presence of these symptoms, pulmonary embolism should always be considered in the differential diagnosis. Blockage of both main pulmonary arteries is a critical condition that can lead to sudden cardiac arrest and death, making it important to distinguish from a myocardial infarction (heart attack).