The respiratory distress due to a heart failure is mainly due to the pumping weakness of the left heart (left heart failure ), which causes the lack of oxygen supply to the organs.
At first, shortness of breath occurs only under physical stress, but in the advanced stages of cardiac insufficiency, even at rest, or even in the case of cardiac stress relieving, shallow storage. If the latter is the case, the doctor speaks of orthopnea.
There are several mechanisms responsible for respiratory distress due to cardiac insufficiency:
On the one hand, the airway resistance (medical: Resistance ) increases, ie it costs more and more force to breathe a certain amount of air into the lungs, because the diameter of the small, leading to the alveoli airways (medically: bronchi and bronchioles ) decreases by the increased filling with tissue fluid. The narrowing of the bronchi may take on dimensions similar to an asthma attack.
This is then systematically referred to as "asthma cardiale", that is, asthma caused by the heart.
The most severe form of fluid accumulation is an immediate emergency requiring treatment with powerful diuretics: pulmonary edema.
On the other hand, in cardiac insufficiency, the skeletal structure of the lungs is altered in terms of increased connective tissue storage (medically: fibrosis ), as the increased stress on the heart due to the pumping weakness of the heart, activation of the sympathetic nervous system and the release of various messengers, inter alia from the kidney leads (eg Renin).
This and the catecholamine called messenger substances of the sympathetic nervous system in the long term for a reconstruction of the heart muscle cells and the very thin, thereby enabling gas exchange, membranes of the lungs.
The latter, as so-called alveolar membranes, constitute the basic building block of a lung bladder (Latin alveolus = blisters) and are essential for proper respiration.
Due to the increased number of messenger substances circulating in the blood, they thicken and store more connective tissue, which makes gas exchange in the lungs more difficult and thus leads to respiratory distress.