Heart rhythm disturbances

When the communication of electrical signals from the anterior chambers to the heart chambers is temporarily or permanently interrupted, it leads to a quite slow or sometimes irregular heart rhythm. The most common symptoms are fatigue, shortness of breath, dizziness and loss of consciousness (syncope). If the conduction disturbance is the result of a treatment with medication, it is often preventable. If it is not, then an implanted pacemaker is necessary.

In the heart's anterior chamber, fast electrical impulses are formed that temporarily override the heart rhythm and make the heart beat a regular 140-190 beats per minute. The heart rhythm disturbance starts and stops abruptly. Sometimes, the periods come quite frequently. The heart rhythm disorder is usually brief and most likely without causing problems, and does not required treatment. For prolonged and extremely troubling episodes, medication treatment or even ablation may be indicated.

An ablation is necessary if the rapid heart rate is frequent, causes many symptoms, and medication for heart rhythm disorders does not work well or is not desired. The chance of a successful ablation of this heart rhythm disturbance is somewhat lower than for other supraventricular tachycardias.

This heart rhythm disturbance can only occur if an extra conduction pathway is present in the AV node. In this case, the electrical current may remain circulating in the junction between the anterior chambers and the chambers. This results in the rapid and simultaneous contraction of the anterior chambers and chambers.

Patients experience strong palpitations, a sense of tightness in their throat, dizziness sometimes, and rarely lose consciousness.

The preferred treatment is an ablation of the extra conduction pathway in the AV node. The chance of a permanent AV block (and thus the need for a pacemaker implant) after the ablation of an AV nodal tachycardia is 0.5%.

Wolff Parkinson White syndrome is a congenital defect, with an extra electrical connection, in addition to the AV node, between the atria and the ventricles. In certain circumstances, this 'accessory' conduction pathway can lead to a 'circle tachycardia' (re-entry tachycardia): an electrical impulse will continue circulating in a circuit made up of the anterior chambers, the AV node, the chambers and the accessory bundle.

If an atrial fibrillation occurs, the atrial impulses are also transmitted to the chambers very rapidly using the accessory bundle. This can lead to a life-threatening atrial or ventricle fibrillation.

An accessory bundle qualifies for electrophysiological testing or possible ablation:

• in case of a tachycardia
• in case of a syncope
• in case the accessory bundle keeps transmitting with high heart rates
• with at-risk professions

Rapid but regular electrical circuits in the anterior chambers can arise around the atrioventricular valves, around the exit of the pulmonary veins and around (surgical) scarring. Whether or not they cause symptoms depends on the velocity with which the electrical impulses are transmitted to the ventricles over the AV node.

The treatment of atrial flutter has the following three goals:

1. prevent heart failure by optimising the ventricular response to the atrial flutter
2. prevent clot formations in the heart, thereby reducing the risk of heart attack and stroke
3. repair the sinus rhythm This can be achieved through medication, an electrical cardioversion or an ablation.

Atrial fibrillation (AF) is one of the most common heart rhythm disorders. They are created by rapid impulses from the pulmonary veins that end up in the left atrium, where they circulate in total chaos, causing the atria to ‘flutter’. Whether or not it causes symptoms depends on the velocity with which the electrical impulses are transmitted to the chambers over the AV node.

The treatment for atrial fibrillation has three goals:

1. prevent heart failure by optimising the ventricular response to the atrial fibrillation
2. prevent clot formations in the heart, thereby reducing the risk of heart attack and stroke Medications can help reduce the blood's capacity to coagulate.
3. repair the sinus rhythm This can be achieved through medication, an electrical cardioversion or an ablation.

Ventricular tachycardia happens when there is rapid electrical activity in the heart muscle. Although this heart rhythm disturbance occurs in a normal heart, it is usually caused by a previous heart attack or by heart muscle disease. Due to the rapid and uncoordinated contraction of the ventricles, blood cannot be circulated efficiently. A ventricular tachycardia can turn into a life-threatening ventricular fibrillation.

The patient usually experiences sudden dizziness or loss of consciousness. Treatment may consist of medication, a cardioversion, an ablation or implantation of a defibrillator.

Ventricular fibrillation is total electrical chaos in the heart’s ventricles. This chaotic activity stops the heart's pumping function. This leads to cardiac arrest. Ventricular fibrillation usually occurs with sudden damage to the heart muscle, such as heart attack.

Ventricular fibrillation can be treated with an external defibrillator during resuscitation (chest compression, ventilation). Recurrent cardiac arrest can be prevented by implanting aninternal defibrillator.

Extra systoles are redundant heartbeats that disturb the normal heart rhythm of the pacemaker cells (sinus node). The cells that generate the extra systoles can be located in the atrium or in a ventricle. Most extra systoles are unpleasant rather than dangerous. Sometimes, though, they can be early symptoms of serious heart disease. They are usually palpable as a (perceptible) short interruption of the heartbeat, followed by a harder beat.

Extra systoles are only treated with medication if they are extremely uncomfortable for the patient. Ventricular extra systoles are sometimes considered for ablation if they are numerous (a minimum of 30% of the total number of heartbeats), such that they lead to heart failure or if there are complaints of the heart pounding.

Brugada syndrome is a congenital condition with an increased risk of sudden cardiac death. If one of the parents is a carrier of the gene, there is a one in two chance that a child will have the syndrome. The incidence varies from five to 50 per 10,000.

The syndrome can manifest itself through dizziness, sudden fainting or even sudden death, even at a younger age. The condition is characterised by an abnormal electrocardiogram, which is sometimes only detected after provocative testing.

Symptomatic patients must be protected with an implanted internal defibrillator.

A fatty wall or fibrosis of the wall of the right ventricle makes it more susceptible to ventricular tachycardia, which can lead to palpitations, dizziness, syncope, heart failure and even sudden death.

The condition is hereditary and follows a progressive trajectory with symptoms first arising during adolescence. The incidence is estimated at 1 per 5000, and is higher among athletes.

The diagnosis is made based on multiple measures: electrocardiogram, Holter monitor, medical imaging using electrocardiography and MRI and a biopsy that can show tissue degeneration.

Treatment consists of medication, ablation and protective treatment by implanting an internal defibrillator.

Long QT syndrome includes conditions characterised by an abnormality in the electrocardiogram: a lengthened interval between the QRS wave and the end of the T wave. The root cause is an abnormal influx of electrolytes to the heart cells, which makes them susceptible to life-threatening heart rhythm disorders, such as ventricular tachycardia or fibrillation.

The condition can be inherited as a genetic condition or it may develop as a result of using certain medication.

If the cause cannot be managed, the implantation of a defibrillator should be considered.