SINUS BRADYCARDIA:My 26-year-old daughter has been told she has sinus bradycardia arrhythmia. What is this?
Arrhythmias are heart rhythm problems. They occur when the electrical impulses to the heart that co-ordinate heartbeats do not work properly.
This can result in the heart beating too fast (tachycardia) or too slow (bradycardia).
Normally the heart beats between 60 and 100 times per minute when resting. Athletes may have a resting heart rate of less than 60 beats per minute because their hearts are very efficient.
Arrhythmias are classified according to where they originate and whether the heart rate is fast or slow.
In this case “sinus” refers to the sinus node, the heart’s natural pacemaker which creates the normal regular heartbeat. “Bradycardia” means the heart rate is slower than normal.
The heart contracts when a small group of cells (the sinus node) in the right atrium send out an electrical impulse.
This causes the right and left atria to contract and the ventricles to fill with blood. The impulse then moves to the atrioventricular node.
From here the impulse travels through the ventricles, causing them to contract, pumping blood throughout the body.
The electrical impulses that cause the heart to contract follow a precise pathway.
Any interruption to these impulses can cause an arrhythmia.
What sort of interruption?
Sinus bradycardia may be caused by malfunction of the pacemaker (sinus node) and is known as a sick sinus.
While this may be caused by some drugs or an underactive thyroid gland, in most people the reason for it is unknown.
Alternatively, a blockage of the electrical pathways may interfere with the movement of electrical impulses throughout the heart.
Some people with sinus bradycardia experience no symptoms and the problem may only come to light during a routine examination. However, symptoms can include angina (chest pain), fatigue, dizziness and light-headedness.
Difficulties when exercising, palpitations, shortness of breath and fainting may also be experienced. Some sufferers report problems with concentration or confusion.
How is sinus bradycardia treated?
Where sinus bradycardia is found to have an underlying cause – hypothyroidism or a drug side effect – then that problem is treated first.
If no underlying cause is found, a pacemaker may be implanted.
This device replaces the job of the atrioventricular node. Placed under the skin, the device uses electrical pulses to prompt the heart to beat at a normal rate.
