Cardiac Output and Venous Return

TIPS:

• Right Atrial Contraction or Pressure (RAC) is the same in the follow cases: Normal = Hemorrhage = Exercise.
• If RAC increases by Cardiac Faillure or Blood Transfusion.

Excellent Explanation !!! Thank you!!!

Q1: An 36 years-old athlete has a sudden ventricular fibrillation during the exercise. What occur with the right atrial contraction  (RAC) and the mean systemic filling pressure (MSFP) one minute before and one minute after ventricular fibrillation?. *Note: RAC is the same that RAP (right atria pressure).

A1: Explanation:

• Normal (not exercising): RAC = 2 ; MSFP = 7
• Before 1 minute AF (Exercising): RAC = 1 ; MSFP = 9
• After 1 minute AF (Cardiac faillure) patient exercising: RAC = (MSFPexercising - RACexercising = 9 - 1 = 8; the RAC needs to increase +8 mmHg to achieve the MSFP during the exercise because the ventricle stopped to pump to keep the MSFP = 9. 
• After 1 minute AF (Cardiac faillure) patient not-exercising: RAC = (MSFPnormal - RACnormal = 7 - 2 = 5; the RAC needs to increase +5 mmHg to achieve the MSFP during the exercise because the ventricle stopped to pump to keep the MSFP = 7. In cardiac faillure always the RAC will increase to compensate. *(See Kaplan Qbank Step1, Question OL597 to practice it).