Bradycardia is an arrhythmia, an alteration of the heart rhythm, characterised by a heart rate lower than usual and, in most cases, is not pathological. There are two types of arrhythmias: fast (tachycardias) and slow (bradycardias or bradyarrhythmias). The Spanish Heart Foundation reports that bradycardias are usually asymptomatic and do not require treatment. Still, when they manifest and produce symptoms -some very disabling- they can be successfully treated with the implantation of a pacemaker.
“In general, it is accepted that a heart rate below 60 beats per minute is bradycardia, although he clarifies that, probably, “if we use the cut-off point of 50, we would find an environment in which bradycardia has more pathological significance”.
Bradycardia occurs when there is a failure in the heart’s electrical system. The impulses originate in the right atrium (in the sinus node) or are transmitted to the rest of the heart (in the atrioventricular node and branches). When the point where the impulses begin fails, we speak of sinus node disease. When what is altered are the structures that conduct the impulse from the atria to the ventricles, we say of the atrioventricular block.
it is a frequent problem that mainly affects older people, although in rare cases it can also appear in young people or children.”
An American study by the Centers for Disease Control and Prevention (CDC) in 2011 estimated the frequency of this condition in 15.2% of men and 6.9% of women. It must be stressed that the percentage of the population has a heart rate below 60 beats per minute, which in many cases is not relevant from a medical point of view.
When it comes to pathological bradycardia, “by far the most frequent cause is the ageing of the heart. “most of the pathological bradycardias that will require the implantation of a pacemaker usually appear in older people, in whom the ageing of the heart causes cells specialised in the generation or conduction of electrical impulses also grow old, degenerate and stop doing their function”. Therefore, the most critical risk factor is advanced age.
Generally, the failure occurs in the heart itself and can have different causes:
- The progressive degeneration of the cardiac electrical system (the most frequent).
- After a heart attack or inflammation of the heart (myocarditis)
- After heart surgery, congenital disabilities (in children).
- But it can also be due to causes other than the heart, such as:
- Taking some medications that slow the heart rate.
- Poor function of the thyroid gland.
- Sleep apnea.
- Potassium or calcium disorders
“It can be expected in older people, as long as it does not produce symptoms. It can also appear generally in people with intense and regular physical exercise.
Many bradycardias are asymptomatic. When they cause symptoms, the most frequent are:
Dizziness or fainting (loss of consciousness)
The heart stops but then starts beating again. This affects blood circulation in the brain, causing dizziness or loss of consciousness, that is, syncope.
In this case, the heart does not stop pumping, but since it has stopped doing it with the normal frequency, when the affected person makes some effort, the heart cannot respond to the increased demand for blood from the tissues. Consequently, there is fatigue, a feeling of suffocation and even a feeling of pressure in the chest.
Jiménez comments that there is a type of pathological bradycardia, an atrioventricular block, “which can cause the heart to stop beating, but temporarily for a few seconds, but permanently, and can cause sudden death .” In these cases, it is necessary to act as soon as possible, “ensuring that there is a stable electrical activity of the heart and maintained over time.”
Other manifestations, such as confusion, memory loss, or difficulty breathing, may also be other manifestations.
The best way to prevent bradycardia is to promote heart health through a healthy lifestyle. These are some of the most important aspects of keeping cardiovascular risk factors at bay
- Do physical exercise regularly.
- Follow a healthy and balanced diet with low sugar, salt and fat content and rich in vegetables, legumes, fruit and whole grains.
- Avoid overweight and obesity.
- Monitor blood cholesterol levels.
- Control blood pressure to avoid hypertension.
- No smoking.
- Limit alcohol.
- Do not use drugs.
Taking the pulse can reveal the existence of a slow heart rate, but a clinical evaluation is necessary to determine its true extent.
First, the symptoms (syncope, dizziness, fatigue, heart failure), the patient’s medical history, the drugs he takes or has taken and whether he has any structural heart disease will be assessed.
Secondly, it is necessary to carry out complementary examinations, such as an electrocardiogram, chest X-ray and blood tests with renal function and electrolytes.
There is no specific drug for bradycardia. “The most important thing is to identify the causes that can produce it, especially if they are causes other than the heart that can be corrected, such as the intake of some drugs or problems with the thyroid gland,” says Rubio. If the cause lies in the heart itself, “the most common is having to implant a pacemaker. It is the most indicated treatment for this pathology, “which also works very well in selected patients,” adds Jiménez
The pacemaker is an electronic device that stimulates the heart and causes it to beat at the rate considered appropriate. It is implanted under the collarbone through a small incision. It generally consists of an electrical impulse generator (the pacemaker itself) and a lead. Still, about five years ago, the first leadless pacemakers began to be implanted, the use of which has been progressively spreading.
Follow-up of asymptomatic patients
Patients with bradycardia considered pathological but without symptoms “should be followed up by a doctor regularly to prevent them from beginning to present symptoms one day. Among the most valuable measures to monitor these patients are periodic electrocardiograms or Holter monitoring, a method of recording the heart’s rhythm for 24 hours.
Sometimes it may be necessary to do a stress test to see the behaviour of the cardiac electrical system during exercise. “For example, If anomalies of the sinus node, the atrioventricular node or the branches are detected, the follow-up must be closer to avoid complications”, indicates Rubio.
The most important symptoms are dizziness or fainting spells, which may appear before other serious problems. “For example, If a patient has them, he should see a doctor as soon as possible, especially if he is elderly or has a heart condition. Uncorrected extreme bradycardia can be fatal if not corrected in time,” warns the cardiologist.