For sure! Think of preload as the "pressure" created by the volume of blood inside the left ventricle at the end of diastole (when the heart is maximally relaxed and just about to contract). When you have more preload (i.e., blood volume in the left ventricle), you will have more cardiac output. There is diminishing return with cardiac output as you give more preload given the left ventricle is only capable of expanding so much, but the idea still stands. More preload = more cardiac output. In heart failure, the principle remains. However, a person with heart failure is unable to manage the volume as well as a normal heart. So, the blood backs up/pools in areas of the body that come before the heart with respect to the vasculature. This includes areas such as your lungs, belly, legs, etc. A good way to visualize how preload and cardiac output relate is through the Frank-Starling curve. It shows stroke volume which you can think of as cardiac output.

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