Which condition is a cause of an acquired murmur?

A. Pus in the pleural space: This describes empyema, a condition in which infection leads to pus accumulation in the pleural space. Empyema is commonly associated with bacterial pneumonia, lung abscess, or thoracic surgery and requires drainage and antibiotic therapy. It does not cause the lung collapse seen in pneumothorax.

B. Collapse of small airways: While airway collapse can occur in conditions like bronchiolitis or atelectasis, it is not the defining feature of pneumothorax. Pneumothorax specifically involves air leaking into the pleural space, which disrupts the negative pressure necessary for lung expansion and results in partial or complete lung collapse.

C. Blood in the chest cavity: This describes hemothorax, a condition in which blood accumulates in the pleural space due to trauma, ruptured blood vessels, or certain medical conditions. Unlike pneumothorax, which involves air in the pleural space, hemothorax requires different management, including drainage with a chest tube and possible fluid resuscitation.

D. Air in the pleural space: Pneumothorax occurs when air enters the pleural space, causing a loss of negative pressure and leading to lung collapse. This can result from chest trauma, spontaneous rupture of alveoli, underlying lung disease, or mechanical ventilation. Symptoms may include sudden chest pain, dyspnea, and decreased breath sounds on the affected side.

A. Cardiac failure: While cardiac failure can lead to changes in heart function, it does not directly cause an acquired murmur. Murmurs are typically due to valvular or structural abnormalities rather than being a direct consequence of heart failure.

B. Coronary artery disease (CAD): CAD can lead to ischemic heart disease and may contribute to heart failure but is not typically associated with the development of an acquired murmur. It does not directly create new murmurs; rather, it can exacerbate existing heart conditions.

C. Congenital malformation: Congenital malformations are structural heart defects present at birth and are classified as congenital causes of murmurs rather than acquired. These murmurs result from anatomical abnormalities rather than changes occurring after birth.

D. Rheumatic fever: Rheumatic fever is an acquired condition that can cause damage to the heart valves, leading to the development of valvular insufficiency or stenosis. These changes can produce an acquired murmur as a result of the inflammation and scarring of the heart valves following the infection.