Coupling of the Heart and Great Vessels
With infinite reservoir, output of heart is dependent on preload, afterload, and ionotropic state. Otherwise, the output is determined by how much blood can flow into the atria during diastole.
Ionotropic state and output of heart determine right atrial pressure. Right atrial pressure determines preload.
Mean circulatory filling pressure – Pmc – estimate of cardiovascular volume. Use central venous pressure, arterial pressure and cardiac output. Pressure in system is determined by capacitance and volume. Venous capacitance is 19X the arterial.
Only if you have pumping will there be a difference in volume between the two sides. If you decrease pumpin, you increase venous pressure.
Pressure is reduced as blood flows through the system.
Decreased vascular resistance causes greater cardiac output for any given filling pressure.
Combine vascular function and starling curve.
Increased resistance will lower venous return and cardiac output and central venous pressure. But it also raises the blood pressure (afterload) causing cardiac output to fall. The net result is decreased CO with little change in central venous pressure.
Cardiac failure will cause your body to increase volume, which will increase central venous pressure and CO.
Change in HR will decrease preload, increase afterload and increase contractility.
Negative pressure breathing will increase CO.
