When hearts go haywire

Heart rhythm problems occur when the electrical impulses that coordinate heartbeats don’t work properly, causing the heart to beat too fast, too slow or irregularly. Photo: Shutterstock

After a long day at work, you’re finally home and have had your dinner.

You sit comfortably next to your freshly-lit scented candles, eagerly turning the pages of your long-awaited read.

Then suddenly it strikes. This disturbing feeling across your chest that feels like your heart is racing.

Taught by an old friend, you manage to count your pulse. An estimated 150 beats a minute!

This is the fifth time this month you’re having this. What is actually happening to your body?

Palpitation is a common presentation to the doctor, and frequently to the cardiologist. But what does it indicate?

Our heart rate is controlled by a system that runs autonomous-ly, which simply means that we cannot control it.

For instance, when we are anxious, the rate can accelerate up to 160 beats a minute, while during sleep, it could go as low as 50 beats a minute.

This describes the physiologi-cal response of our heart to our body’s needs and is completely natural. However, when our heart rate changes unexpectedly, it can mean otherwise.

This article will cover the commonest cause of tachycardia (which means fast heart rate) – supraventricular tachycardia, known in short as SVT.

It is usually caused by an abnormal conducting pathway (wire) in the heart.

Given the right timing and trigger, it can turn into a short-circuit loop that accelerates the heart beat up to 200 beats a minute.

This abnormal loop will take over the heart’s natural heart rate, rendering it no longer autonomous.

Imagine that your heart is an aquarium pump that usually runs 60-100 cycles a minute.

If you were to accelerate the pump to 200 cycles a minute, the pump might fail and the water system might clog up, causing spillover and leakage.

The same goes for our heart. If you experience an SVT, you will be predisposed to fainting spells, and even heart failure, especially if you have an underlying abnormal heart structure.

These abnormal pathways can either be something inborn, which means that you have it since birth, or something that gets acquired later in life.

I’m sure that you have heard stories about friends being declined for a job as a pilot because the ECG (electrocardio-gram) appears abnormal, despite him being young and healthy, forcing him to get his heart checked or the condition rectified before further inter-views can be arranged.

This is a classic example of an inborn extra wire in the heart, which is discovered during a routine screening test.

This group of patients will have to undergo further investi-gation in order to determine the risk this may carry.

Not uncommonly, SVT could also be due to an abnormal “firing” due to an “irritable” area of heart at the cellular level. We call this atrial tachycardia.

Why does this happen?

It is usually due to an imbalance in the ion-pump system in the heart cells, leading to abnormal beats that “escape” into the conduction system.

Typically, it is worse during stress or exercise, but can occasionally happen even while the body is resting.

This tachycardia can be perceived as frequent missed heart beats.

Not uncommonly, this can cause difficulty in measuring blood pressure or heart rate using commercial measuring machines due to the irregular heart rate, which will mess with the machine’s algorithm.

I know of a friend who actually changed his blood pressure monitoring device twice, thinking that it was faulty, only to find out later that it was in fact due to his under-lying abnormal heart rhythm.

SVT is easily treated and cured by radiofrequency ablation (RFA).

This is a procedure where a metal-tipped catheter is used to locate the source of the tachy-cardia.

Once found, a local heating process is used to render the “culprit area” non-irritable or non-conductive.

The whole procedure is to aim for cure.

It has a high success rate and low recurrence for SVT.

Other than RFA, selected patients can be put on medica-tion, especially if the frequency of attacks is low and minimally symptomatic.

But again, it all depends on the type and severity of the SVT.

If the SVT caused you to faint and fall, then it has to be treated aggressively via RFA.

This is to reduce the risk of complications, which may ensue during the next episode.

Alternatively, for those who do not wish to be dependent on oral medications, RFA could also be a good option as a first-line therapy in suitable cases.

I have seen patients who go in and out from the hospital emer-gency department to receive their “usual” intravenous medi-cation to terminate the SVT episodes, not realising the availability of a procedure that can essentially cure the condition.

Don’t let your palpitations limit your daily life.

Consult your healthcare provider to learn more about treatment options.

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Dr Choy Chun Ngok is a consultant cardiologist and electrophysiologist. For further information, e-mail [e-mail]. The information provided is for educational and communication purposes only and it should not be construed as personal medical advice. Information published in this article is not intended to replace, supplant or augment a consultation with a health professional regarding the reader’s own medical care. The Star disclaims all responsibility for any losses, damage to property or personal injury suffered directly or indirectly from reliance on such information.