What is it about ?
The heart is made up of two upper chambers (the atria) and two lower chambers (the ventricles). The heart muscle (myocardium) contracts under the influence of an electrical stimulus. This electric current originates in the sinus node, a collection of cells found in the right atrium. From the sinus node, current travels to the heart muscle through a special electrical conduction system. A second node (atrioventricular node), located between the atrium and the ventricle, connects the nerves in the atrium with those in the ventricles.
When the current reaches the muscle of the ventricles, they contract. Normally, the heart beats between 60 and 100 times per minute. If the heart rate is over 100 beats per minute, it is called tachycardia.
In supraventricular tachycardia , the increased heart rate is caused by stimuli from a point in the atrium that is not the sinus node. The electric current originates in the wall of the atria or what is called the atrioventricular node. This heart rhythm disorder is unique in that the abnormal current is returned each time to its place of origin and that it follows, so to speak, continuously in a closed circuit. This circuit occurs from the atrium or atrioventricular node.
How to recognize it?
The person usually suffers from palpitations, and the heart rate increases. Usually, supraventricular tachycardia starts and ends suddenly. It can last a few seconds or manifest itself in a prolonged crisis.
The heart rate is always regular and is usually between 140 and 220 beats per minute. The increased rhythm of the heart causes an unpleasant sensation.
Sometimes more vague symptoms can also occur, such as dizziness or nausea .
How is the diagnosis made?
Your doctor will first do a physical examination by feeling your pulse and examining your heart. This will already allow him to determine whether the heart rate is regular or irregular.
The main diagnostic test is the ECG (electrocardiogram), which is a video of the heart. To be able to detect an abnormality and evaluate it, the doctor must do an ECG at the time of a seizure. This is not obvious. This is why it is sometimes necessary to monitor the activity of the heart over a longer period ( Holter recording ). The doctor then applies a small ECG machine to the chest to record the activity of the heart for 24 or 48 hours.
What can you do ?
Ask your GP for advice if you experience palpitations, especially if you feel unwell. Some heart rhythm disturbances are dangerous; you should therefore always have an ECG so that the correct diagnosis can be made. In the event of an abnormality on the ECG, the general practitioner will most often refer you to a cardiologist.
If supraventricular tachycardia is diagnosed, and the seizures are short and do not come back too often, you can try to stop the seizure yourself. Breathe deeply and then exhale forcefully with your mouth and nose closed. This is the Valsalva maneuver, the one you use to unblock your ears when you’re on a plane.
What can your doctor do?
Treatment is tailored to the underlying condition. Medicines that slow the heart rate can sometimes control the heart rhythm disorder . In acute, life-threatening cases, the drugs should be administered by infusion under supervision in the hospital.
If the problem is due to the presence of an accessory pathway in the heart’s impulse conduction system, it may be removed . This involves destroying the accessory pathway at the origin of the heart rhythm disorder , under general anesthesia. This is done through a catheter introduced through the groin or arm and pushed into the atrium of the heart.
You can also treat with cardioversion , which delivers an electric shock delivered by a defibrillator, to return the heart rate to normal. It is especially used when the heart rhythm disorder is associated with another rhythm disorder ( atrial fibrillation ).
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