What is cardiac asthma?

What is cardiac asthma?

Cardiac asthma is a disease directly related to the heart and in particular to heart failure. Its symptoms mimic those of bronchial asthma, which can be confusing. In reality, this condition occurs in patients already suffering from heart failure. It is an advanced stage of left-sided heart failure or even pulmonary oedema. Most of the time, it occurs in elderly subjects, in whom there is no previous history of bronchial asthma.

Why is it likened to bronchial asthma?

The diagnosis of cardiac asthma, or pseudo-asthma, is initially based on a clinical picture: cough, dyspnoea and wheezing (whistling sounds that can be heard with a stethoscope caused by the narrowing of the small airways in the lungs). Respiratory symptoms, which manifest as an asthma attack, are in fact caused by congestive heart failure.

Bronchial asthma, on the other hand, is an inflammatory disorder of the respiratory tract (bronchi and bronchioles), characterised by reversible airflow obstruction. Asthma manifests itself through episodes of coughing, wheezing and dyspnoea.

In cardiac pseudo-asthma, patients dealing with shortness of breath attribute their symptoms to lung damage, whereas the very origin of dyspnoea is based on heart failure.

Indeed, dyspnoea is one of the leading symptoms of heart failure.

Why does heart failure cause respiratory symptoms?

It is important to know that blood carries the oxygen that is essential for the proper functioning of the organs in the human body. During heart failure, the heart is unable to perform its role as a cardiac pump and therefore does not send enough blood to the organs. It loses its muscular strength and can no longer contract sufficiently. As a result, the heart is not able to ensure a blood flow that can fulfil the organs' needs in oxygen (O2). This leads to a vicious circle: the heart tries to compensate for the body's needs by increasing its heart rate (beats per minute) and blood flow. 

However, these efforts can cause harmful consequences, such as cardiac hypertrophy (the heart muscle grows and the cardiac tissue becomes fibrous and less elastic) or ventricular dilatation (enlargement of the ventricular walls to accommodate sufficient blood). This increased workload and changes in the heart's morphology worsen the damage over time.

Indeed, heart failure causes lung congestion: the heart pump is inefficient, blood accumulates and stagnates in the heart chambers. Because of the excess pressure, blood infiltrates into the lungs, which become engorged with blood. It is therefore the presence of water in the lungs that causes this respiratory discomfort. 

In some cases, acute pulmonary oedema can occur if the pseudo-asthma attack is sudden, accompanied by rapid breathing (polypnoea), excessive sweating and high blood pressure. This is a medical emergency, where the patient is in a state of respiratory distress and needs to sit down. At this stage, water has filled the pulmonary alveoli.

To go further: we talk about left-sided or right-sided heart failure, depending on the ventricular involvement. In fact, the heart is made up of two chambers: a right ventricle and a left ventricle. Right-sided heart failure occurs after left-sided heart failure.

Symptoms

Dyspnoea, the first sign of heart failure

Initially, breathing difficulties occur during exertion (when the body's needs increase, the heart cannot adapt), until they occur in a state of rest (the patient has trouble performing normal movements without feeling discomfort). The New York Heart Association (NYHA) Functional Classification is commonly used to monitor the impact of heart failure on a patient and assess the severity of the dyspnoea:

• Class I: dyspnoea upon out-of-the-ordinary exertions: no discomfort in everyday life; 
• Class II: dyspnoea upon significant exertion: slight discomfort in everyday life;
• Class III: dyspnoea upon minor exertion: marked discomfort in everyday life (no problem while at rest);
• Class IV: constant dyspnoea, both at rest and during exertion: discomfort even at rest, restricting the patient's living space to the home or even the bedroom.

Other respiratory symptoms such as shortness of breath, cough and wheezing are present. As water enters the pulmonary bronchi, they tend to shrink, so the passage of air makes a characteristic wheezing sound as the patient breathes in and out.

Fatigue

The heart is not able to supply the body with the energy it needs, causing chronic fatigue in the patient. The organs and muscles are not fuelled with enough glucose (sugar) and oxygen.

Oedemas (abnormal tissue swelling due to excess liquid)

The presence of oedema should alarm the patient: swelling may appear in the lower limbs or even in the neck and/or around the liver in the case of right-sided heart failure. They reflect cardiac pump's difficulty to circulate blood throughout the body.

Treating heart failure

Heart failure is a chronic condition that often occurs as a result of another cardiovascular disease (coronary heart disease, valvular heart disease, high blood pressure, etc.). It cannot be cured but many treatments can stabilise it. Treatment for cardiac asthma is not the same as care for bronchial asthma. It is not the same physiopathological mechanism.

The importance of lifestyle and dietary measures

The therapeutic strategy is based on the severity of symptoms and the functional impact of heart failure on the vital organs, meaning the kidneys, lungs, liver, etc.

The discovery of heart failure is not necessarily accompanied by the introduction of medication.

To begin the following measures are put in place:

• A low-salt diet is essential, as high blood pressure can worsen the condition;
• Following this, stabilisation of the underlying case of high blood pressure is vital if it exists;
• Stopping alcohol intake, especially if the damage to the heart is due to alcohol abuse;
• Stopping smoking, which is the number one cardiovascular risk factor (causing atherosclerosis) and the number one enemy of the arteries;
• Regular physical exercise,
• A healthy and balanced diet.

Only then can a treatment be recommended, depending on the patient's profile.

Treatment usually includes 3 types of medication:

• Diuretics - increase the elimination of salt and water via the urine in order to relieve some of the workload on the heart
• ACE inhibitors - reduce the heart's workload by dilating the veins and arteries and decreasing blood volume
• Beta blockers - drugs that reduce the heart's workload by slowing the heart rate

Monitoring is put in place to assess the effectiveness of the treatments and how the patient tolerates them. Associations or modifications may be made as needed.

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