What does Central Venous Pressure (CVP) estimate?

Central Venous Pressure (CVP) is a measurement that estimates the pressure in the thoracic vena cava near the right atrium, and it primarily reflects the preload, which is the volume of blood in the ventricles at the end of diastole. In the context of heart failure, monitoring CVP can provide valuable insights into the patient's fluid status and the filling pressures of the heart, which are crucial for the management of heart failure.

Preload is directly influenced by the volume of blood returning to the heart, and therefore, CVP serves as a useful indicator of this preload level. When interpreting CVP readings, a higher CVP often indicates excessive preload, which can lead to congestion, particularly in heart failure patients, while a lower CVP can suggest inadequate circulating volume.

The other options, while relevant to cardiac function, do not accurately describe what CVP estimates. Cardiac output measures the volume of blood the heart pumps per minute, right ventricular function pertains specifically to the performance of the right ventricle, and myocardial oxygen demand relates to the heart's metabolic requirements. Therefore, focusing on preload provides the most accurate interpretation of what CVP estimates in clinical practice regarding heart failure management.