What is an arrhythmia and what types are there?
As the name suggests, an arrhythmia is a disturbance in the normal rhythm of the heart.
There are 3 types of arrhythmias:
- Bradyarrhythmias or bradyarrhythmias: in which the heart rhythm is slower than normal, producing symptoms of dizziness. Syncope (transient loss of consciousness) or asphyxia.
- Tachycardias: in which the heart rate is much higher than normal.
- Atrial fibrillation: a very common type of arrhythmia that can manifest as bradycardia or tachycardia, producing an irregular heart rhythm.
How is an arrhythmia diagnosed?
The diagnosis of an arrhythmia is made by a simple baseline Electrocardiogram (ECG) or by a 24-48 hour Holter ECG recording.
There are some arrhythmias that have a repetitive and very short duration of presentation (between several seconds and a few hours), which prevent the patient from accessing a health service to have an ECG performed. In this case, real-time ECG recorders are useful. The most commonly used is the subcutaneous Holter, which is a small device that is implanted under the skin and continuously records the electrocardiogram, detecting and recording any arrhythmia automatically or manually by patient activation. In recent years, devices associated with smartphones and smart watches, capable of recording an ECG strip and storing it for later viewing by the cardiologist, are gaining acceptance. They have already been accepted by the main clinical practice guidelines as useful and reliable instruments for the diagnosis of any arrhythmia.
Pacemakers are one of the treatments for arrhythmias. What are they for and how do they work?
Pacemakers are the definitive treatment for bradycardias. They generally consist of a generator with a battery and circuitry that allows different programming and sends electrical impulses through one or more wires that are inserted in different parts of the heart to achieve cardiac contraction.
What is the risk of a patient with a pacemaker suffering a new arrhythmia or heart failure?
Pacemakers are very reliable devices that last between 8 and 10 years, after which they must be replaced due to battery depletion.
Once a pacemaker has been implanted, it is highly unlikely that the patient will suffer bradycardia due to device malfunction.
Should the implantation site of pacemakers be changed?
Classically, pacemakers have been implanted in the right ventricle, producing a non-physiological contraction of the heart that over time can result in a deterioration of cardiac function. More than 20 years ago, we demonstrated that it was possible to implant pacemakers in the normal conduction system of the heart, producing a contraction similar to the natural one and avoiding this long-term deterioration of the contraction force. Therefore, we recommend pacemaker implantation in the conduction system (His bundle) and this is our standard practice.
How are tachycardias treated?
Most tachycardias are treated today by cardiac catheterization and ablation. Basically, it consists of introducing electrodes into the heart and identifying the focus or circuit of the tachycardia. Once the focus has been identified, it is eliminated by the application of radiofrequency heat, although elimination by cold freezing (cryoablation) is also possible.
Ablation success is greater than 95% in most tachycardias. In the case of atrial fibrillation, the success rate is 65% and it is not uncommon to have to repeat the procedure.