Heart rate is one of the key elements used to gauge our heart health. It can simply be defined as the number of times our heart beats in a minute. A high heart rate due to temporary external factors including physical activity and stress is normal. But a persistently faster heartbeat is a cause for concern and requires medical intervention to diagnose or rule out any underlying heart condition.
Any anomaly in the heart could make the heart beat faster (tachycardia) or slower (bradycardia) than the regular rate. This condition of irregular heart rate is called arrhythmia.
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Decoding irregular heartbeats
Dr Kumar Kenchappa, Consultant-Interventional Cardiologist, Manipal Hospital Hebbal, Bengaluru, points out that the heart has four chambers. The two upper chambers are called atria, while the two lower chambers are called ventricles. Cardiac muscles in the four heart chambers contract as a result of the electrical impulses from the sino-atrial node (SA node) and ensure blood circulation in our body.
“The upper chamber arrhythmias are not dangerous, while the lower chamber arrhythmias are more serious and could even lead to death,” Dr Kenchappa adds.
The heart chambers are interconnected with valves that open and close when the muscles contract in sync to ensure unidirectional blood flow. The rate of contraction of these muscles is called heart rate (heartbeat) and the normal pattern of the electrical impulses from the SA node is called heart rhythm. Any changes in the heart rhythm results in the heart beating either slower or faster than the normal rate of 60 to 100 heart beats per minute.
Experts point out that these variations could affect people of all ages and can be caused by a wide range of factors, such as heart disease, high blood pressure, stress, medications, and genetics. The most common forms of arrhythmia leading to tachycardia are:
“Supraventricular tachycardia arises from the atrial chamber above the ventricles,” says Dr Amit Kumar Singhal, senior consultant, cardiology, Fortis Escorts hospital, Jaipur.
“In people with supraventricular tachycardia, the electrical signals that regulate the heartbeat are abnormal, causing the heart to beat faster than normal,” he adds.
In supraventricular tachycardia, the heart rate goes up to 160-170. “This condition is usually benign and not life-threatening. It can be easily treated with medication,” he adds.
But in extreme cases and for those with persisting bouts of supraventricular tachycardia, intense therapy might be required. The heart chambers will not be completely filled with blood due to the irregular heart beats and contraction. It could affect blood circulation.
“Ventricular tachycardia arises from the ventricles. They are riskier and more life-threatening”, says Dr Singhal.
Dr Kenchappa says, ventricular tachycardia is more common in people with existing heart disease, especially those above 35 years. The primary signs of ventricular tachycardia include frequent episodes of sudden unconsciousness, dizziness, nausea, and breathlessness. “Ventricular tachycardia can be life threatening, if not treated immediately,” he adds.
“Atrial flutter rises from the atria and usually contracts at a very rapid rate between 200 to 300 per minute, which can increase to the range of 300 to 450,” says Dr Singhal.
“Atrial flutter can be fatal as it can lead to a decrease in the heart’s ability to pump blood effectively affecting the cardiac pumping function,” he adds.
Dr Kenchappa says, “Compared to supraventricular tachycardia, atrial flutter is considered more serious.” Atrial flutter usually occurs with valvular dysfunction, he adds.
“Atrial fibrillation is the most common type of cardiac arrhythmia in the upper chamber. In this condition, the heart rate is usually fast,” says Dr Kenchappa. High blood pressure, underlying heart and lung disease, congenital heart disease and increased alcohol intake are all risk factors for atrial fibrillation.
“In atrial fibrillation, there is always a risk of developing brain stroke,” he adds.
He further adds that Non-Valvular Atrial Fibrillation (NVAF) is an increasingly common condition. It is commonly found in people who do not have valvular heart disease but still develop atrial fibrillation due to vascular conditions like hypertension. Non valvular atrial fibrillation could be a strong predictor of stroke in some people.
Ventricular fibrillation (VF)
Dr Singhal says, “Ventricular fibrillation is the most serious form of arrhythmia, in which the heart continues to beat but does not effectively contract.” The ventricles contract at a very rapid rate leading to a disruption in the blood supply. The most common signs of VF are exhaustion and loss of consciousness. Dr Singhal adds that it could occur with a severe heart attack or a cardiac arrest.
Early intervention is very important. Simple tests like ECG and Holter monitoring can diagnose irregular heart rate related complications. “If arrhythmias get treated early it could prevent further damage to the heart,” says Dr Kenchappa. A healthy diet and active lifestyle also helps us to keep our heart healthy.
Irregular heart rate, occurring frequently without any valid external reason could be a manifestation of an underlying cardiac condition. It is recommended to consult a medical expert for further examination. People already diagnosed with cardiac conditions especially those who have suffered heart attack or stroke should take these conditions seriously.