The rise in pressure begins simultaneously with ventricular depolarization (the QRS). When the right ventricle pressue is measured from a pulmonary artery catheter, the distance between the catheter tip and the transducer produces a delay between the QRS and the appearance of the rise in ventricular pressure (note the red line).
With a sinus rhythm,
a small pressure rise in the right ventricular pressure occurs as the atrial
contracts and increases the ventricular volume. This pressure rise
is identified by the blue arrow.