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Cardiac Arrhythmia (Arrhythmia)

An arrhythmia is a problem with the rate or rhythm of the heartbeat. During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm.

PubMed Health Glossary
(Source: NIH - National Heart, Lung, and Blood Institute)

Arrhythmia

An arrhythmia (ah-RITH-me-ah) is a problem with the rate or rhythm of the heartbeat. During an arrhythmia, the heart can beat too fast, too slow, or with an irregular rhythm.

A heartbeat that is too fast is called tachycardia (TAK-ih-KAR-de-ah). A heartbeat that is too slow is called bradycardia (bray-de-KAR-de-ah).

Most arrhythmias are harmless, but some can be serious or even life threatening. During an arrhythmia, the heart may not be able to pump enough blood to the body. Lack of blood flow can damage the brain, heart, and other organs.

Understanding the Heart's Electrical System

To understand arrhythmias, it helps to understand the heart's internal electrical system. The heart's electrical system controls the rate and rhythm of the heartbeat.

With each heartbeat, an electrical signal spreads from the top of the heart to the bottom. As the signal travels, it causes the heart to contract... Read more about Cardiac Arrhythmia NIH - National Heart, Lung, and Blood Institute

What works? Research summarized

Evidence reviews

Amiodarone for preventing sudden cardiac death

Sudden cardiac death (SCD) is an important cause of death nowadays. People at high risk (mainly with any sort of heart disease) die unexpectedly from cardiac causes, primarily from arrhythmia (an irregular heartbeat). The treatment of choice is a device called an implantable cardiac defibrillator (ICD), but it is not widely available in low‐ or middle‐income countries. Amiodarone, an antiarrhythmic medication, might reduce the occurrence of these events and could be an alternative when an ICD is not available.

Efficacy and safety of shen song yang xin capsule for cardiac arrhythmia: a systematic review

Bibliographic details: Hu H, Tang HQ, Li JH, Yang LL, Tang WJ, Zhou ZR.  Efficacy and safety of shen song yang xin capsule for cardiac arrhythmia: a systematic review. Chinese Journal of Evidence-Based Medicine 2011; 11(2): 168-173 Available from: http://www.cjebm.org.cn/oa/DArticle.aspx?type=view&id=201102010

Implantable cardioverter defibrillators for the treatment of arrhythmias and cardiac resynchronisation therapy for the treatment of heart failure: systematic review and economic evaluation

Study found that implantable cardiac defibrillators reduced all-cause mortality in people at increased risk of sudden cardiac death as a result of previous ventricular arrhythmias or cardiac arrest, remote myocardial infarction or ischaemic/non-ischaemic heart failure and LVEF ≤ 35%. Cardiac resynchronisation therapy reduced all-cause mortality and improved other outcomes in people with heart failure as a result of left ventricular systolic dysfunction and cardiac dyssynchrony when compared with optimal pharmacological therapy. The devices were cost-effective at a willingness-to-pay threshold of £30,000 when compared with optimal pharmacological therapy.

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Summaries for consumers

Amiodarone for preventing sudden cardiac death

Sudden cardiac death (SCD) is an important cause of death nowadays. People at high risk (mainly with any sort of heart disease) die unexpectedly from cardiac causes, primarily from arrhythmia (an irregular heartbeat). The treatment of choice is a device called an implantable cardiac defibrillator (ICD), but it is not widely available in low‐ or middle‐income countries. Amiodarone, an antiarrhythmic medication, might reduce the occurrence of these events and could be an alternative when an ICD is not available.

Epidural analgesia for heart surgery

The use of thoracic epidural analgesia (TEA) in heart surgery is controversial. TEA produces a high level of pain relief and may reduce some of the adverse effects that are associated with heart surgery. Along with these potential benefits of TEA there is a widespread fear that TEA could cause bleeding into the epidural space (haematoma). We have conducted a review of medical trials to compare the effect of general anaesthesia (GA) alone with GA in combination with epidural analgesia on major complications in patients undergoing elective heart surgery. We identified 5035 titles of which 31 publications met all the inclusion criteria. These 31 publications reported on a total of 3047 patients, 1578 patients with GA and 1469 patients with TEA as well as GA. The risks of death, heart attack and stroke were not statistically significant, however our analysis showed statistically significant reductions in the risk of arrhythmias and pulmonary complications. Despite this, our findings must be viewed with caution. Epidural analgesia in heart surgery remains controversial in the absence of a sufficiently large and statistical significant effect on mortality, stroke, or myocardial infarction and while the risks are unclear.

Perioperative increase in global blood flow to explicit defined goals and outcomes following surgery

Death and serious complications commonly occur following major surgery and are a significant public health problem. These outcomes might be prevented by using fluids and drugs to maintain the supply of oxygen and other nutrients to vital organs. Global blood flow, adjusted to maintain specific targets, might serve as a proxy in determining whether administered fluid and drugs maintain critical nutrient supply. In this Cochrane review of 31 studies conducted in 5292 patients undergoing major surgery, the use of fluids, with or without additional drugs, to achieve defined targets associated with increased total blood flow did not reduce mortality. There was a reduction in the number of patients with complications and the length of time patients stayed in hospital (by 1.2 days). However, the quality of the studies in this area was mediocre.

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Terms to know

Blood
A tissue with red blood cells, white blood cells, platelets, and other substances suspended in fluid called plasma. Blood takes oxygen and nutrients to the tissues, and carries away wastes.
Bradycardia
An abnormally slow heart rate. Thresholds for different age, gender, and patient populations exist.
Heart
The hollow, muscular organ that maintains the circulation of the blood.
Tachycardia
Rapid beating of the heart, usually defined as greater than 100 beats per minute.

More about Cardiac Arrhythmia

Photo of an adult

Also called: Cardiac dysrhythmia, Conduction disorder of the heart, Disorder of heart conduction, Disorder of heart rhythm, Irregular heartbeat

See Also: Palpitations, Atrial Fibrillation, Heart Block

Other terms to know: See all 4
Blood, Bradycardia, Heart

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