Cardiac Mechanics Simulator Tutorial

Exercise Set 1

III. The Frank-Starling Law of the Heart

Otto Frank (circa 1890) is credited with the seminal observation that peak ventricular pressure increases as the end-diastolic volume is increased. This observation was made in an isolated frog heart preparation in which ventricular volume could be measured with relative ease. Around the mid 1910's, Starling and coworkers observed a related phenomenon, which they presented in a manner that was much more useful to physiologists and ultimately to clinicians. They measured the relationship between ventricular filling pressure (related to end-diastolic volume) and cardiac output.

The observations of Frank and of Starling form one of the basic concepts of cardiovascular physiology: Cardiac performance (its ability to generate pressure or to pump blood) increases with preload. However, factors other than preload are important for determining cardiac performance: ventricular contractility and afterload properties. Both of these factors can influence the Frank-Starling Curves.

1. Use the "Filling Pressure" slider to vary preload, and then plot the relationship of EDV and CO. Plot at least 5 different points. This curve will represent the ^+baseline^+ Starling curve.

2. Change ventricular contractility and generate a new Starling curve. How do the two curves differ?

3. Return contractility back to baseline and now change ventricular afterload. How does afterload affect the Starling curve?

Filling Pressure Threshold for Elastance/MAP effect is off. Was set to 50.0