There are a lot of things that can affect your resting heart rate. Let us break it up into physiological and pathological factors. So if you exercise a lot, your resting heart rate can be quite low. The normal heart rate is 60 to 100.
Less than 60 is a low heart rate, above 100 is a fast heart rate. Again, it depends if you are a very active person. Your heart rate tends to be on a lower range if you are those really active people; your heart rate can go as low as 40. So when we look at the heart rate, we got to look in terms of the context of the patient. So of course, that's the physiological aspect.
Next, we look at the pathological factors. We look at the medication. We check if patients are taking any core competent medication which suppresses heart rate like beta-blockers, or they have a hormonal disturbance like low thyroid functions such as hypothyroidism. Sometimes, these can give you a fast heart rate, or some electrolyte abnormality such as a lack of electrolytes like potassium.
The third pathological cause will be real conduction abnormalities. These patients can be diagnosed in different ways. Number one, let's say they have a slow heart rate. We will see whether they can mount to what we call a tachycardic response, so it means the heart rate can go up to a predetermined heart rate level, determined by us based on their age. We check if they can run with stress, then we know the low heart rate may not be anything significant.
The second test we can do is a Holter monitor, cardiac monitoring for at least 24 hours to see what is their heart rate range that is presented to you in the clinic, and when you do an ECG while you are 50, does your heart rate go even lower when you are sleeping at night because you are resting, whether there are any abnormal pauses or rhythms that the holter test can pick up over a 24 hours period. So, our holter can monitor up to 2 weeks in our clinic. Its an outpatient test so usually when we talk about holters, the monitor period can go as long as 2 weeks, but usually we monitor about 1-3 days.
