Learn the Causes of Tachycardia

Normal Adult Heart Rate

The function of the heart is to ensure that oxygenated blood and glucose are supplied to the cells of the body and that carbon dioxide is removed from them. The carbon dioxide is removed from the body via the lungs as we exhale and oxygen is supplied when we inhale. The heart responds to increased or decreased oxygen demand by beating faster or more slowly, respectively. The heart rate is controlled by a group of cells in the heart called the sinus node. At rest, most adults will have a heartbeat of between sixty and 100 beats per minute. The rate is often slightly higher in women than in men and tends to be slower for athletes than sedentary members of society.

What Is Tachycardia And What May Cause It?

Tachycardia is a condition where the heart continues to beat at a higher rate than normal, despite the individual being at rest. This article will explore the causes of tachycardia and its potential consequences.

The heart consists of four chambers (two ventricles and two atria); blood enters at the top of the heart (into the left and right atria) and as it contracts, blood is pumped into the ventricles and out of the heart. As noted above, the heart rate is controlled by electrical signals produced by the sinus node. In tachycardia, the speed of the electrical signals sent to the upper or lower (or both) chambers of the heart increase, resulting in a faster heartbeat.

Tachycardia may produce no symptoms or problems, but the condition is associated with an increased risk of stroke and sudden cardiac arrest which may be fatal and perturbation of normal cardiac function, so it should always be investigated.

A number of different factors can lead to tachycardia and these include heart disease, congenital factors, heavy alcohol consumption, smoking, high caffeine intake, thyroid problems, medication, certain forms of illegal drug abuse, an imbalance of the body’s electrolytes or high blood pressure. The condition may also be idiopathic in origin (i.e. nobody can find a cause).

The Five Types of Tachycardia

There are five main types of tachycardia:

A). Atrial fibrillation is caused by chaotic electrical stimulation of the atria and may last from a few hours to days – treatment may be needed to resolve the condition. The electrical signals produce rapid, uncoordinated and inefficient contractions of the atria.

B). Atrial flutter is produced by a fast (250 to 350 BPM), regular pattern of electrical signals which cause weak atrial output. It may last from a few hours to days – treatment may be needed to resolve the condition. It may result from cardiac surgery (typically within the first week after surgery) and is often accompanied by atrial fibrillation.

C). Supraventricular tachycardia (SVT) is due to an (usually congenital) abnormality of the heart’s circuitry above the ventricles which causes the electrical signals to overlap. Episodes may last from a few seconds to several hours.

D). Ventricular fibrillation is a life-threatening condition whereby chaotic electrical signals cause the ventricles to quiver rather than pump. Unless a normal rhythm is quickly restored, death is inevitable. It tends to occur in people with an underlying heart condition or following serious trauma (including suffering a lightening strike).

E). Ventricular tachycardia is due to abnormal electrical signals being sent to the ventricles. The rapidly beating heart doesn’t allow the ventricles to fill completely, so the body doesn’t get the oxygen it needs. The condition is a medical emergency as it is life-threatening. It is often associated with heart disease and/or a previous heart attack.

These are the causes of tachycardia which can be a benign or a life-threatening condition depending on its exact cause. If you believe that you may be suffering from an unaccountably fast heart rate, contact your physician promptly.

References

  1. The heart: https://www.fi.edu/learn/heart/
  2. Tachycardia, The Mayo Clinic: https://www.mayoclinic.com/health/tachycardia/DS00929