GROSS ANATOMY

Detailed explanation-1: -This often occurs as a result of untreated high blood pressure. In this case, the chambers of the heart become thicker, having to work harder against high blood pressure. At first, the end-diastolic volume decreases because the thicker heart muscle squeezes more strongly.

Detailed explanation-2: -At all ages, ventricular output depends on end-diastolic volume. An increase in stroke volume or cardiac output occurs when end-diastolic volume is increased (the Frank-Starling relation).

Detailed explanation-3: -Stroke volume is the amount of blood ejected from the ventricle with each cardiac cycle. It can be readily calculated by subtracting the end-systolic volume from the end-diastolic volume. Multiplying the stroke volume by the heart rate yields the cardiac output, typically reported in liters per minute.

Detailed explanation-4: -A reduced stroke volume at the same end-diastolic volume results in reduced ejection fraction. If afterload is reduced by decreasing aortic pressure, the opposite occurs-stroke volume and ejection fraction increase, and end-systolic volume decreases (green loop in figure).