Lung Atelectasis also referred to as Atelectasis lung, occurs when a lung or its lobe partly or fully gives away (collapses) as a result of the shrinkage of the alveoli, which are the tiny air sacs, inside the lung. Lung atelectasis is a difficulty that affects the respiratory system after a surgery.
Any sudden and considerable dip in blood pressure observed after running, which does not return to near normal levels within 30 minutes or so, also indicates potential cardiac issues. An individual with their blood pressure constantly below 90/60 mmHg should consult a medical professional right away.
1 Normal blood pressure is when your blood pressure is lower than 120/80 mmHg most of the time.  High blood pressure (hypertension) is when your blood pressure is 140/90 mmHg or above most of the time.