Arrhythmia

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By Medifit Education

ARRHYTHMIA

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ARRHYTHMIA DEFINITION

Heart rhythm problems (heart arrhythmias) occur when the electrical impulses that coordinate your heartbeats don’t work properly, causing your heart to beat too fast, too slow or irregularly.

Heart arrhythmias (uh-RITH-me-uhs) may feel like a fluttering or racing heart and may be harmless. However, some heart arrhythmias may cause bothersome — sometimes even life-threatening — signs and symptoms.

Heart arrhythmia treatment can often control or eliminate fast or irregular heartbeats. In addition, because troublesome heart arrhythmias are often made worse — or are even caused — by a weak or damaged heart, you may be able to reduce your arrhythmia risk by adopting a heart-healthy lifestyle.

 

ARRHYTHMIA CAUSES

The electrical impulses that cause the heart to contract must follow a precise pathway for it to work properly. Any interruption to these impulses can result in arrhythmia. The human heart consists of four chambers – the chambers on each half of the heart form two adjoining pumps, with the atrium (upper chamber) and the ventricle (lower chamber).

When a heartbeat occurs the less muscular and smaller atria contract and fill the relaxed ventricles with blood. The contraction starts when a small group of cells in the right atrium (the sinus node) send an electrical impulse which causes the right and left atria to contract. The impulse then moves to the atrioventricular node (at the center of the heart) on the pathway between the atria and ventricles. From here the impulse leaves the atrioventricular node, travels through the ventricles, causing them to contract and pump blood – this blood pumps throughout the body.

For a person with a healthy heart the process works properly and he/she should have a heart rate of between 60 and 100 beats per minute when resting. The fitter you are the lower your resting heart rate. Olympic athletes, for example, will usually have a resting heart rate of less than 60 beats per minute because their hearts are very efficient.

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ARRHYTHMIA PATHOPHYSIOLOGY

Cardiac arrhythmias are ambiguous symptoms. Intracardiac as well as extracardiac alterations may be responsible. There is little direct information from the ECG concerning their pathophysiological mechanism. Bradycardic as well as tachycardic arrhythmias can be the result of two different fundamental disturbances: alterations of impulse formation (automaticity) or alterations of impulse conduction. Either one of these, or both of them acting together, may be responsible for the arrhythmia. Tachycardias due to disturbances of impulse formation may be brought about by enhanced firing of regular pacemakers (sino-atrial node, av-node, ventricular conduction system), by abnormal automaticity occurring in ordinary atrial or ventricular myocardium, or by triggered activity due to early or delayed afterdepolarizations. Bradycardic disturbances of impulse formation are primarily concerned with sino-atrial nodal function. Bradycardic conduction disturbances mainly impair sinoatrial or atrioventricular propagation causing partial or total conduction block. Tachyarrhythmias due to disturbances of conduction are generated by re-entry of excitatory waves either along anatomically preformed pathways or around functional obstacles (refractory zones) with excitable gaps being more or less pronounced. On the cellular level, altered activities of ionic channels or transport systems play a significant part. Such changes are caused by: alterations of electrolyte composition (potassium, sodium, calcium), acidosis or alkalosis, autonomic and hormonal influences, membrane active metabolites (long-chain acylcarnitine, lysophosphatidylcholine), drugs (class I and III antiarrhythmics, cardiac glycosides) and poisons. In disturbances of conduction other aspects like geometry of pathways or cable properties (anisotropic conduction, coupling resistances between cells) are of particular significance.

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ARRHYTHMIA SYMPTOMS

Many arrhythmias cause no signs or symptoms. When signs or symptoms are present, the most common ones are:

  • Palpitations (feelings that your heart is skipping a beat, fluttering, or beating too hard or fast)
  • A slow heartbeat
  • An irregular heartbeat
  • Feeling pauses between heartbeats

More serious signs and symptoms include:

  • Anxiety
  • Weakness, dizziness, and light-headedness
  • Fainting or nearly fainting
  • Sweating
  • Shortness of breath
  • Chest pain

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ARRHYTHMIA DIAGNOSIS

To diagnose a heart arrhythmia, your doctor will review your symptoms and your medical history and conduct a physical examination. Your doctor may ask about — or test for — conditions that may trigger your arrhythmia, such as heart disease or a problem with your thyroid gland. Your doctor may also perform heart-monitoring tests specific to arrhythmias. These may include:

  • Electrocardiogram (ECG). During an ECG, sensors (electrodes) that can detect the electrical activity of your heart are attached to your chest and sometimes to your limbs. An ECG measures the timing and duration of each electrical phase in your heartbeat.
  • Holter monitor. This portable ECG device can be worn for a day or more to record your heart’s activity as you go about your routine.
  • Event monitor. For sporadic arrhythmias, you keep this portable ECG device available, attaching it to your body and pressing a button when you have symptoms. This lets your doctor check your heart rhythm at the time of your symptoms.
  • Echocardiogram. In this noninvasive test, a hand-held device (transducer) placed on your chest uses sound waves to produce images of your heart’s size, structure and motion.

If your doctor doesn’t find an arrhythmia during those tests, he or she may try to trigger your arrhythmia with other tests, which may include:

  • Stress test. Some arrhythmias are triggered or worsened by exercise. During a stress test, you’ll be asked to exercise on a treadmill or stationary bicycle while your heart activity is monitored. If doctors are evaluating you to determine if coronary artery disease may be causing the arrhythmia, and you have difficulty exercising, then your doctor may use a drug to stimulate your heart in a way that’s similar to exercise.
  • Tilt table test. Your doctor may recommend this test if you’ve had fainting spells. Your heart rate and blood pressure are monitored as you lie flat on a table. The table is then tilted as if you were standing up. Your doctor observes how your heart and the nervous system that controls it respond to the change in angle.
  • Electrophysiological testing and mapping. In this test, doctors thread thin, flexible tubes (catheters) tipped with electrodes through your blood vessels to a variety of spots within your heart. Once in place, the electrodes can map the spread of electrical impulses through your heart. In addition, your cardiologist can use the electrodes to stimulate your heart to beat at rates that may trigger — or halt — an arrhythmia. This allows your doctor to see the location of the arrhythmia and what may be causing it.

 

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ARRHYTHMIA TREATMENT

A variety of drugs are available to treat arrhythmias. These include:

  • Antiarrhythmic drugs. These drugs control heart rate and include beta-blockers.
  • Anticoagulant or antiplatelet therapy. These drugs reduce the risk of blood clots and stroke. These includewarfarin (a “blood thinner”) or aspirin. Another blood thinner called Pradaxa (dabigatran) was approved in 2010 to prevent stroke in people withatrial fibrillation.
  • Because everyone is different, it may take trials of several medications and doses to find the one that works best for you.

By Medifit Education

www.themedifit.in