Technology

A number of agents have shown significant effect on cardiac function and cause disorders related to arrhythmia. Some of the chemicals have a potential to cause bradycardia, the slowing of the heart rhythm, while others can cause tachycardia, the quickening of the heart rhythm. Vaughan (1992) points out that agents such as caffeine, amphetamine, cocaine, psychotropics, beta blockers and sympathomimetics have exhibited potential effects on the heart rate both in vivo and in vitro. Conditions such as temperature can also cause significant changes on the heart rate. This paper will examine examples of other causes of arrhythmia and relate the causes to the effect on the heart rate. The consequence of arrhythmia can either be detrimental or beneficial to the heart function and these effects can be transient or long-term effect depending on the cause.

The human heart is made up of four chambers consisting of two auricles and two ventricles which contract in a coordinated and a precise manner. Heart contraction is initiated with an electrical impulse with the SA (sinoartrial) node acting as a natural pacemaker. This signal then leaves the SA node to enter the upper chambers or auricles. From the auricles, the signal enters the AV (artriolventriclular) node and then through the lower chambers of the heart (ventricles). However, mistakes may occur along the pathway resulting to arrhythmic (bradycardia or tachycardia) conditions (Vaughan, 1992). Interruption in the energy conduction in cardiac cells can lead to bradycardia, a reduced heart rate. A fast heart rate can result from defect ventricles, a condition called ventricular tachycardia.   Supraventricular tachycardia causes the fibrillation of the atria and AVNRT (atriventricular nodal reentry tachycardia). Vaughan (1992) identifies that  arrhythmia can be blamed on several agents such as caffeine, amphetamines, beta blockers, cocaine, sympathomimetics and psychotropic agents to be responsible for arrhythmia. Supraventricular arrhythmias can be a lifelong problem and can impact the lifestyle of the afflicted patient and family and friends. However, with the advent of radiation technology, radiofrequency ablation greatly replaces the lifelong dependency on drug therapy.

Agents such as calcium channel blockers and beta blockers have been employed in reducing the pace of the heart while anti-arrhythmic drugs raise the heart rate significantly to the normal pace. Tachycardia is mistaken to the increase in cardiac output. This concept, in theory, may be conceived as tachycardia being an activator of the heart. However, tachycardia is a serious life threatening condition which is indicative of high blood pressure. Attempts by drug abusers to gulp dozes of cardiac activators are risky and can complicate the entire cardiac system.