The sinus node is the body’s own pacemaker – a collection of specialized cells in the heart which emits a regular electrical impulse that causes the heart to beat rhythmically.
Bradycardia is a heart rate that is slower than normal. Thus, sinus bradycardia is a slow heart rate that is caused by the malfunction of the sinus node.
The sinus node malfunction may be because the electrical impulse is blocked in the node, the sinus node momentarily stops or the signal alternates its speed.
Sinus bradycardia can occur normally and naturally under certain circumstances.
During sleep, normal children and adults can experience considerably lowered heart rates. Very fit people, like athletes, have a resting heart rate lower than average, as do some elderly people, though not for the same reasons.
None of these instances is due to any medical problems. However, if a lower heart rate is accompanied by symptoms such as dizziness or shortness of breath, it is considered a problem.
The normal heart rate is considered to be 60 to 100 beats per minute; a rate below 60 is considered to be bradycardia.
Mild bradycardia may not cause any noticeable symptoms, but when the heart rate drops below 50 beats per minute the heart may not be able to deliver sufficient blood to the body.
This causes symptoms that are similar to those associated with many heart problems, like faintness, weakness, chest pain, shortness of breath, palpitations and confusion.
There are some conditions and diseases that predispose people to sinus bradycardia. These include an under-active thyroid gland, aging, heart diseases and some medications.
Your doctor will want to identify possible causes and the type of bradycardia you have so that a suitable treatment can be implemented for you.
You will probably have an electrocardiogram and maybe a cardiac stress test to record your heart’s rhythm.
If nothing shows up in this test, you may have one of two types of portable ECG machines given to you to take home and wear for a 24 hour period to measure your heart rhythm for a longer time period.
Other tests may be given to see if you have any other underlying condition that might be causing your sinus bradycardia.
Mild cases of sinus bradycardia are usually monitored, especially if your symptoms are mild and are not upsetting you.
Any medications you have been on may be checked and monitored to make sure they are not causing your bradycardia. Underlying conditions, which might be contributing to your erratic heart beat, will be treated.
If your sinus bradycardia is more severe or the symptoms are troubling you, the treatment is usually an electronic pacemaker. This is implanted under the skin and takes the place of your sinus node, to the extent that is necessary, to correct your heart rate.