The heart refills during the release phase of chest compressions.

• A. False
• B. During systole
• C. Only during inhalation
• D. True

Answer: (D)

During chest compressions, the heart refills during the release (decompression) phase because the chest recoil lowers intrathoracic pressure and pulls blood back into the heart. This passive venous return increases end-diastolic filling, so the next compression ejects more blood. Complete chest recoil is essential to maximize venous return and overall CPR effectiveness. Filling isn’t driven by the active compression or by inhalation; it mainly happens when the chest springs back up after each push.