Cardiac Cycle

PV Loops

• External work is the work of ejecting blood from the heart and is given by:

$$\begin{array}{rlr}{W}_{\text{external}}& =\int P\cdot dV+K{E}_{\text{ejected blood}}& \\ & \approx \int P\cdot dV& (K{E}_{\text{ejected blood}}\approx 0\text{ for heart at rest})\end{array}$$

Preload

• The point of MV closure moves to the right resulting in:
  • Increased stroke volume
  • Both systolic and diastolic blood pressure increase, but systolic increases more thereby increasing pulse pressure

Afterload

Contractility

Compliance