Ventricular filling occurs in how many phases?

Ventricular filling occurs in two primary phases during the cardiac cycle: early rapid filling and diastasis, followed by atrial contraction which contributes to the final phase of ventricular filling. The early rapid filling phase occurs due to the pressure gradient between the atria and ventricles when the ventricles are relaxed. This allows blood to flow passively into the ventricles. The second phase, diastasis, is a period of relative stability where the filling slows down as the pressures in the atria and ventricles begin to equalize. Following this, atrial contraction pushes additional blood into the ventricles, completing the filling process. Understanding these phases is crucial for interpreting echocardiograms and assessing diastolic function.