• What Are Arrhythmias?
Overview Of Arrhythmias
Type Of Arrhythmias
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|What Are Arrhythmias?
Any abnormality in the rhythm or rate of your heartbeat is called an arrhythmia. They occur when the electrical impulses that regulate the timing of heartbeats (or contractions of the heart), do not work properly. They can range in severity from the incidental harmless skipped heart beat to life-threatening emergencies. During an arrhythmia, the heart can beat too slow, too fast or in an irregular manner. A heartbeat that is too slow is known as bradycardia and one that is too fast is tachycardia (both also come under the general term palpitations, although not all palpitations are caused by arrhythmias). If palpitations are noted and are not easily attributed to drinking too much coffee, emotional stress or strenuous exercise, a doctor should be consulted to rule out any possible underlying medical cause. While some arrhythmias may be a cause for worry, fortunately advances in treatment means that the prognosis is good in most cases. Millions of American's have arrhythmias but they are particularly common in older people with heart disease. About 2.2 million Americans have atrial fibrillation, the most common type of arrhythmia. Statistically, of all the types of arrhythmia, ventricular fibrillation is the most likely to cause sudden cardiac death (an estimated 335,000 every year, US). See Heart disease stats (America) and UK heart disease statistics, as well as what a regular heart beat looks like).
Heartbeat, Heart rate and Pulse. What's The Difference?
Causes of arrhythmias: Every second an electrical impulse starts in the right atrium of the heart (picture of heart) and travels through the heart, triggering one single heartbeat or contraction of the heart that pumps blood through the body. An arrhythmia occurs when this electrical signal is either blocked or delayed. The signal starts in the 'pacemaker' area of the heart (technically called the sino-atrial node, S-A node). The S-A node sends out an electrical signal prompting other cells in the heart to contract so that blood is pushed into ventricles. Another node, the atrio-ventricular or A-V node is prompted to stop the flow of blood, allowing the ventricles to fill with blood so that it can then be pumped out to the body. An arrhythmia occurs when these signals are interrupted. The most common causes for signals to fail include:
The following are typical symptoms of arrhythmia:
1. Underlying heart disease, in particular coronary heart disease (CHD).
There are quite a few different types of arrhythmias but they tend to fall into 4 main categories: (1) premature contractions, (2) supraventricular arrhythmias (fast heart rates), (3) ventricular arrhythmias and (4) bradyarrhythmias (slow heart rates):(1) Premature (Extra) Contractions
One of the most common types of arrhythmia, premature contractions, are usually quite harmless. Very often they do not cause symptoms, but if they do it may feel like a fluttering or sometimes a thump in the chest. They occur when the heart's chambers contract sooner than normal, breaking the regular heartbeat. Premature contractions do not require treatment and can be bought on by too much caffeine, exercise, stress or smoking.
(2) Supraventricular Arrhythmias
Atrial Fibrillation (AF)
Paroxysmal Atrial Tachycardia (PAT)
(3) Ventricular Arrhythmias
Ventricular Tachycardia (VT)
Bradycardia, or 'brady' are arrhythmias in which the heart beats slower than normal. A slow heart rate is strictly defined as 60 beats per minute (bpm). Medical problems do not however usually occur until heart rates fall below 40 bpm. Some people may have normally slow heart rates which are not considered dangerous, athletes in particular commonly have a bpm below 60. But in other people a slow heart rate may be due to a serious underlying condition. Certain drugs, particularly in the elderly, can cause bradycardia.
Arrhythmia diagnosis: If an arrhythmia is suspected the doctor’s first goal is to determine the type of arrhythmia present by ordering an ECG (also known as an electrocardiogram or EKG. An ECG is a simple and non-invasive test which records the electrical activity of the heart. As arrhythmias can come and go, it may be necessary to wear a miniaturized version of the ECG called a Holter Monitor for 24 hours. Other possible tests include an Event Monitor, echocardiogram, stress tests and electrophysicological testing. The latter involves threading tiny electrodes through the veins and into heart, a procedure which requires hospitalization and experienced cardiologists.
Arrhythmia treatment: Most arrhythmias can be treated with medication or surgical implants.
Arrhythmia prevention: The best prevention for arrhythmias is to reduce your risk of CHD (see CHD prevention). As smoking, caffeine intake and extremely low calorie intake increase the chances of developing arrhythmias in younger people (in particular), lifestyle changes in this area may also be necessary. Recent studies show that while stress and strong emotions (such as anxiety) may contribute to an episode of arrhythmia, it does not generally cause it. This can be comforting news to those diagnosed with the condition as it means that there is no need for family members or friends to walk on egg shells around them.
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