During inspiration in a patient with cardiac tamponade, what happens to left ventricular preload and arterial pressure?

During inspiration in a patient with cardiac tamponade, what happens to left ventricular preload and arterial pressure?

• A. Increases
• B. Decreases
• C. No change
• D. Increases LV preload but decreases BP

Answer: (B)

In tamponade, inspiration causes a fall in left ventricular preload and arterial pressure due to ventricular interdependence under a rigid pericardial constraint. As you inspire, venous return to the right heart increases because intrathoracic pressure becomes more negative. The constricted pericardium prevents the heart from expanding outward, so the right ventricle fills more and pushes the interventricular septum toward the left ventricle. This septal shift reduces left ventricular filling, lowering LV preload. With less blood available to be ejected, the stroke volume drops and arterial pressure, especially systolic pressure, falls during inspiration, producing pulsus paradoxus. So, both LV preload and arterial pressure decrease during inspiration in cardiac tamponade.

In tamponade, inspiration causes a fall in left ventricular preload and arterial pressure due to ventricular interdependence under a rigid pericardial constraint. As you inspire, venous return to the right heart increases because intrathoracic pressure becomes more negative. The constricted pericardium prevents the heart from expanding outward, so the right ventricle fills more and pushes the interventricular septum toward the left ventricle. This septal shift reduces left ventricular filling, lowering LV preload. With less blood available to be ejected, the stroke volume drops and arterial pressure, especially systolic pressure, falls during inspiration, producing pulsus paradoxus. So, both LV preload and arterial pressure decrease during inspiration in cardiac tamponade.