In the context of tachycardia, how does it affect the duration of diastole and ventricular filling time?

In tachycardia, the heart beats at an accelerated rate, which leads to a shortened duration of the cardiac cycle. This reduction in cycle length primarily impacts diastole, the phase of the cardiac cycle when the heart muscle relaxes and the chambers fill with blood.

During tachycardia, the decreased time spent in diastole results in less time available for the ventricles to fill with blood between beats. Consequently, this leads to a reduction in preload, which is the amount of blood entering the ventricles before contraction. Preload is determined by venous return and the duration of diastole; with a shorter diastolic phase, there is insufficient time for optimal ventricular filling, which ultimately decreases the end-diastolic volume. Thus, the relationship established illustrates how increased heart rate can shorten the duration of diastole and consequently reduce preload.