Splitting of S2, also known as physiological split, normally occurs during inhalation because the decrease in intrathoracic pressure increases the time needed for pulmonary pressure to exceed that of the right ventricular pressure. A widely split S2 can be associated with several different cardiovascular conditions, including left bundle branch block, pulmonary stenosis, and atrial septal defect.
when is the second sound of the heartbeat produced
during inhalation