ARRHYTHMIAS
What is it?
Arrhythmias are normal rhythm changes of the heart.
In arrhythmias we can perceive and record rhythm or rate changes of the heart. The normal heartbeat rate is between 60 and 100 cycles, or beats, per minute. In children, these levels are usually higher. In heartbeat rate changes, the beats present timing changes from the time elapsing between one beat and the other. Minor changes in these intervals may be considered normal. Changes in heartbeat rate or in the conductance of impulse can be lethal (sudden death), symptomatic (syncopes, dizziness, palpitations) or can be asymptomatic.
Arrhythmias can be asymptomatic or symptomatic, depending on its intensity and on the patient's clinical condition. Ailing hearts can tolerate less well an arrhythmia that would likely be asymptomatic in a healthier heart.
Certain arrhythmias may be assessed by the physician when performing the clinical examination. The most precise way to demonstrate and record an arrhythmia by electronic means, from electrocardiograms, to portable monitors, to Intensive Care Unit equipments. Additionally, there are biotelemetry monitors, in which patients are outfitted with a small recording device to their bodies, transmitting the signs, via radio frequency, to central monitors. Classification of arrhythmias according to the frequency of the heartbeat:
Tachycardia
When the heart beats more than 100 beats per minute in the adult patient. When that happens as a response to physical stress it is considered normal and, after a few minutes, this number should be back to a normal frequency. When the tachycardia persists or is manifested at rest, it can be a sign of some pathologic alteration. It is recommended to consult with your doctor. It should be noted that tachycardia is not synonymous with heart attack.
Bradycardia
It is a condition in which the heart beats less than 60 beats per minute. This may be considered normal in individuals showing good physical condition. However, with cardiac rates below 60 beats per minute, albeit transitory, a cardiologist should be consulted.
Classification of arrhythmias according to rhythm changes
Heartbeats are normally originated in a focus located in the right auricle, designated sinus node. The electric stimuli therein generated spread over to a node located at the junction of the auricles. There, the conductance of the stimulus is retarded somewhat (so that the auricles are able to contract before the ventricles), from whence the stimulus follows towards the ventricles through a conducting systems having two bundles, one for each ventricle, causing their contraction, which is called systole. The period of time in which the heart is not in contraction is designated diastole – it is the relaxing period of the cardiac muscle.
Normal cardiac stimuli are produced in the sinus node located in the right auricle and trigger heart contractions, beats, called systoles. When this node is not active, due to any ailment, for example, many other heart cells located in different parts of the heart can originate electric stimuli capable of triggering heartbeats. These latter heartbeats are designated extrasystoles, which can occur even when the sinus node is active. The individuals affected are not always aware of the arrhythmias caused by extrasystoles.
Extrasystoles may be originated in the auricles, ventricles, as well as in the sinus and atrioventricular nodes, which can surpass and prevail over the stimuli normally generated therein. Extrasystoles are normally followed by a more prolonged relaxation period (diastole). Extrasystoles can be unifocal or multifocal, depending on the different sites in which they are originated
Extrasystoles are not always a sign of heart disease; however, when they are perceived it is advised to consult with a cardiologist. Extrasystoles usually occur randomly in relation to normal systoles. In case of regularity, an extrasystole occurring after each normal systole, this is called bigeminy. If they always occur after two normal systoles, this is called trigeminy. Extrasystoles may occur sporadically; an occurrence of up to ten per minute is not always considered a sign of heart disease.
Fibrillation
It can be auricular and ventricular, depending on the site of origin of the heartbeats. Auricular fibrillation is the most commonly encountered chronic arrhythmia, in which impulses may have a rate of up to 600 beats per minute. Of these impulses only a few can cause contractions of the ventricles; such an elevated rate would not be compatible with the life expectancy of people affected. On the other hand, ventricular fibrillation is more severe, since it is tolerated only when it has a short duration. The heart is not capable of maintaining an efficient circulation if the cardiac rate is too elevated. It can be treated with medication or with cardioversion
Auricular Flutter
It is an arrhythmia in which the ectopic focus of the auricles is originated from 250 to 350 impulses per minute, and in which of every two, three or four impulses one passes on to the ventricles. The treatment may be via medication or cardioversion.
Cardiac arrest
it happens when the heart ceases to contract. If it lasts for a short duration it will likely go unnoticed; if it lasts longer, it may cause dizziness, syncope and even sudden death. When the heart stops beating for a few minutes, alterations are triggered in the organs most sensitive to the lack of oxygen. Of these, the most sensitive is the nervous system. Thus, the heart may return, spontaneously or by means of medical procedures, to its activity. However, neurological alterations already established will likely be irreversible.
Palpitations
Feeling one's heartbeats is called palpitations. Normally, the heartbeats is not perceived or felt by people. In certain stressing or strenuous situations , we may perceive that the heart 'is beating' in the chest or neck, what is not necessarily a sign of a disease.
Likewise, individuals affected by extrasystoles may be aware or not of their occurrence. The best way to record an arrhythmia is by means of an electrocardiogram.