Cardiac asthma (heart asthma) is the occurrence of the symptom complex of
- Shortness of breath (dyspnoea), in some cases severe shortness of breath, which improves in an upright position (orthopnoea),
- Nocturnal coughing and other asthmatic symptoms resulting from left heart failure with congestion of the lungs.
Causes: What causes cardiac asthma?
The cause of cardiac asthma is left heart failure (weakness of the left heart to deliver the blood volume required by the body in a required time) with backward failure and congestion of the lungs. This means that the weakness of the left heart‘s pumping action causes the blood to back up into the lung‘s upstream circulation, increasing the pressure in the pulmonary circulation vessels. This causes fluid and blood components (transudate) to escape from the pulmonary vessels into the alveoli. Secondarily, the bronchial tubes may become narrow (bronchial obstruction) and the symptoms of cardiac asthma may occur. A further increase in pressure in the pulmonary circulation leads to the formation of further transudate, which is coughed up as a foamy, reddish-coloured fluid; this results in acute pulmonary oedema.
Symptoms of cardiac asthma
As a consequence of the congestion of the lungs, the most common symptoms are nocturnal coughing, shortness of breath (dyspnoea) and severe shortness of breath with improvement in an upright position (orthopnoea). The symptoms are more pronounced at night or when lying down, because unlike in an upright position, gravity causes the pressure in the pulmonary circulation to rise. For this reason, patients can put their upper body on cushions at night to reduce the symptoms.
In extreme cases, cardiac asthma can develop into acute pulmonary edema with severe shortness of breath, a feeling of suffocation and foamy sputum. In addition to coughing attacks, as many people know from bronchial asthma, one of the main symptoms of cardiac asthma is shortness of breath. This becomes particularly severe and restrictive when coughing at night (“heart cough“) or under great stress.
The severe heart disease, which usually underlies all cardiac asthma, leads to a backlog of blood in the pulmonary circulation. This increased volume of blood in the lungs can enter the lungs as a result of the changed pressure conditions that are caused, resulting in reduced pulmonary ventilation and oxygen exchange. Coughing is one of the main symptoms of both bronchial and cardiac asthma.
Originally, coughing is a protective reflex of the body to eject possible foreign bodies that may obstruct ventilation when the lungs are less ventilated. In cardiac asthma, the backflow of blood into the pulmonary circulation leads to a constant transfer of fluid into the lung tissue. This fluid irritates the lungs and leads to the protective reflex of coughing.
Pulmonary oedema refers to the accumulation of water in the lungs. It can be caused by many different diseases, with heart disease being one of the most common causes of pulmonary edema. Due to the reduced pumping function in the presence of a heart failure, the blood backs up into the pulmonary circulation. Here, the increased blood volume increases the pressure on the small blood vessels directly adjacent to the lungs, which are responsible for oxygen exchange. This increased pressure leads to the transfer of fluid from the bloodstream into the lungs and thus to pulmonary oedema.