How fast or how slow the heart beats may indicate that a person has a heart condition. By Michael Lim

WHILE most people associate chest pain and shortness of breath with heart disease, those with abnormalities of the heart rhythm may experience fast or irregular heart beat, or dizzy spells which may eventually culminate in a fainting episode. Tragically, some may meet with sudden death if the problem is not detected earlier.

Dizzy spells may indicate heart problems

Patients with abnormal heart rhythms can be divided into two major categories. The first group consists of those whose heart is failing or there is failure of the transmission of electrical impulses in the heart. Those in this group will tend to develop dizzy or fainting spells and will usually require a pacemaker.

One of my patients, Mr A, falls into this group. He had been having episodes of dizzy spells lasting seconds for the past year and during the latest episode, he was admitted to a hospital after he had fainted. He was examined by brain specialists and heart specialists and was discharged after nothing abnormal was detected. His daughter was told that it may be all in the mind.

He saw me for a second opinion and after two days of monitoring, he was found to have episodes where the heart stopped beating for a few seconds. As his symptoms were transient and infrequent, it was not surprising that it was not easy to detect. A pacemaker was subsequently implanted for him to allow the heart to beat even when his own heart stopped beating spontaneously. Since then, he has had no more dizzy spells.

Fast heart beats may be potentially dangerous

The second group comprises those who have episodes of abnormally fast heart rhythms affecting the upper or lower heart chambers. In this group, the most dangerous rhythm is a condition called ventricular fibrillation (VF) in which electrical impulses fire off from multiple sites in the lower chambers of the heart at an extremely fast rate, resulting in the quivering of the lower chamber of the heart and the inability of the heart to pump blood.

The VF has to be converted back to a normal rhythm by administering an electrical shock to the heart with a machine called a defibrillator. If this is not achieved within minutes, the person will not survive or may end up with permanent brain damage.

VF is seen mainly in those who have damage to the heart, commonly due to a heart attack. It can also be due to a congenital condition. Another of my patients in his 40s, Mr B, first saw me for a routine checkup. His electrocardiogram (ECG) showed evidence of an uncommon abnormal heart pattern consistent with an inherited condition called Brugada syndrome which will predispose him to sudden death. He did not have symptoms but upon further questioning, he revealed that his father had died suddenly in his 40s.

A few weeks later, he developed abnormal heart rhythms which required the implantation of a pacemaker with the ability to convert a life threatening rhythm to normal (an automatic cardiac implantable defibrillator or AICD). This will reduce his risk of sudden death substantially.

Abnormal heart rhythms and stroke

There is a third group of patients who have both episodes of sudden fast heart rate and alternating episodes of failure of transmission of electrical impulses. Most commonly, these patients have electrical impulses firing off from multiple sites in the upper chambers of the heart at an extremely fast rate, resulting in quivering of the upper chambers of the heart (atrial fibrillation or AF) interspersed with episodes of extremely low heart rate.

These patients will also need a permanent pacemaker. However, the presence of AF will increase the risk of clot formation in the heart and if the clot travels to the brain, it can result in a stroke.

Detecting heart rhythm abnormalities

Among the abnormal heart rhythms, VF accounts for the large majority of life threatening heart rhythms and is the main mechanism of sudden cardiac death. Early detection of abnormal heart rhythms can prevent the development of serious complications.

A 12-lead electrocardiogram (ECG) is both inexpensive and useful for the detection of an abnormal electrical pattern due to an inherited rhythm abnormality. An ultrasound study of the heart can detect underlying damage to the heart muscle as a result of a heart attack, viral infection of the heart or an inherited heart muscle abnormality – all these conditions will increase the risk of VF.

Unfortunately, in the real world, these episodes of abnormal heart rhythms occur infrequently and transiently, making it difficult to detect. Doctors today have an entire array of detection devices which include handheld mobile ECG recording devices, mobile phones with ECG recording capabilities, wearable ECG monitoring devices and continuous ECG recorders to help them diagnose the type of abnormal heart rhythm.

Treatment choices

In most patients, the abnormal rhythm detected is usually innocuous and does not require any medication. Sometimes, something as easy as decreasing caffeine intake will suffice. I had a young patient who developed AF after drinking several cups of coffee during a conference to keep himself awake. He took my advice to stay away from caffeine and he did not have further recurrent episodes of AF.

For those with fast abnormal heart rhythms, medication will usually control the rhythm. Occasionally, special procedures such as the insertion of a special catheter into the heart chambers to ablate the focus or electrical circuit causing rhythm may be required.

While it may seem like a godsend to have AICD implanted for those with high likelihood of sudden death from VF, it is known that these patients develop anxiety and depression especially if they have had an electrical shock from the AICD. This is not to mention the high cost and social adjustments such as avoiding using mobile phones on same side, not standing near theft detector gates, and avoiding metal detection wands.

So, the next time you have recurrent dizzy spells or episodic fast heart rhythm, do not forget that it could be due to your heart.