A Swan-Ganz catheter permits evaluation of cardiac function by measuring:

• A. Pulmonary artery pressure and the pulmonary capillary wedge pressure
• B. Central venous pressure only
• C. Left atrial size on imaging
• D. Systemic arterial pressure variations

Answer: (A)

A Swan-Ganz catheter, or pulmonary artery catheter, is used to read the heart’s pressures from the right side and the pulmonary circulation to assess how well the heart is filling and pumping. The two key values it provides for evaluating cardiac function are the pulmonary artery pressure and the pulmonary capillary wedge pressure. The wedge pressure is obtained by inflating a balloon to temporarily occlude a small branch of the pulmonary artery; the pressure measured beyond that occlusion reflects the pressure in the pulmonary capillaries and, indirectly, the left atrial pressure. This gives a direct estimate of left-sided preload, which is crucial for understanding left ventricular filling and overall cardiac function. The other options don’t capture this specific role: central venous pressure can be measured, but it doesn’t assess left-sided pressures; left atrial size is determined by imaging like echocardiography; and systemic arterial pressure variations require an arterial line, not a pulmonary artery catheter.