The main symptoms of heart failure are also known as cardiac insufficiency:
- Shortness of breath (medical: dyspnoea) and
- Edema, i.e. the accumulation of fluid in the tissue
Breathlessness in connection with heart failure
The shortness of breath caused by cardiac insufficiency is mainly due to the weakness of the left heart pumping (left heart failure), which results in a reduced supply of oxygen to the organs. Initially, shortness of breath occurs only under physical exertion, but in the advanced stages of heart failure it can also occur at rest or even when the heart is placed flat and relieved. If the latter is the case, the physician speaks of orthopnea.
Several mechanisms are responsible for the shortness of breath caused by heart failure: On the one hand, the resistance of the airways (medical term: resistance) increases, i.e. it takes more and more effort to breathe a certain amount of air into the lungs, because the diameter of the small airways leading to the pulmonary alveoli (medical term: bronchi and bronchioles) decreases due to the increased filling with tissue fluid. The constriction of the bronchi can take on dimensions similar to an asthma attack. This is then systematically referred to as “cardiac asthma“, i.e. asthma caused by the heart.
The most severe form of fluid accumulation is an emergency requiring immediate treatment with highly effective diuretic drugs: pulmonary edema. On the other hand, the basic structure of the lung is also altered in the sense of increased connective tissue storage (medically: fibrosis), since the increased load on the heart associated with the pumping weakness of the heart leads to an activation of the sympathetic nervous system as well as to the release of various messenger substances from the kidneys (e.g. renin). This and the messenger substances of the sympathetic nervous system, known as catecholamines, ensure long-term reconstruction of the heart muscle cells and the very thin membranes of the lungs, which enable gas exchange.
As so-called alveolar membranes, the latter are the basic building blocks of a pulmonary alveoli (lat. alveolus = vesicle) and are essential for proper breathing. Due to the increased amount 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 breathing difficulties.
