Shortness of breath and increasingly
impaired function are typical in patients with pulmonary hypertension.
They are often unable to climb even ten steps and simple daily tasks become
insurmountable challenges. Frequently, the cause is a constriction
of the pulmonary arteries. This reduces the amount of oxygen transported and
results ultimately in oxygen deficiency. The lungs are where gases are exchanged
between the blood and the air inhaled into the body. Oxygen is taken up and
enriches the red blood cells. During physical exertion, the arteries dilate so
that every heartbeat can transport enough blood containing the oxygen the
body needs from the lungs. One reason for the arteries dilating in this way is a
messenger substance formed as the end product of a biochemical reaction chain
triggered by nitric oxide in the arterial walls. This reaction chain is
disrupted in patients with pulmonary hypertension and arterial dilation thus
worsens increasingly. In addition, the walls of the arteries thicken,
constricting the passageways for the blood. Eventually the amount of blood
passing through the lungs is insufficient to ensure an adequate
supply of oxygen to the body and the patient experiences shortness of breath.
As a result, the heart tries to pump more blood through the lungs. This increases
pulmonary blood pressure to as much as ten times its normal value, yet without
achieving adequate oxygen throughput.