Cardiac arrest

Introduction 
Sudden cardiac arrest is the sudden, unexpected loss of heart function, breathing and consciousness. Sudden cardiac arrest usually results from an electrical disturbance in the heart that disrupts its pumping action, stopping blood flow to the rest of the body.

Sudden cardiac arrest is different from a heart attack, which occurs when blood flow to a portion of the heart is blocked. However, a heart attack can sometimes trigger an electrical disturbance that leads to sudden cardiac arrest.

Sudden cardiac arrest is a medical emergency. If not treated immediately, it causes sudden cardiac death. With fast, appropriate medical care, survival is possible. Administering cardiopulmonary resuscitation (CPR) — or even just compressions to the chest — can improve the chances of survival until emergency personnel arrive.         (Uptodatecom, 2015)

Presentation
Signs & symptoms 

·         No pulse

·         No breathing

·         Loss of consciousness

Sometimes other signs and symptoms precede sudden cardiac arrest. These may include fatigue, fainting, blackouts, dizziness, chest pain, shortness of breath, weakness, palpitations or vomiting. But sudden cardiac arrest often occurs with no warning. (Mayoclinicorg, 2015)

Heart conditions that can lead to sudden cardiac arrest

·         Coronary artery disease. 

·         Heart attack. 

·         Enlarged heart (cardiomyopathy). 

·         Valvular heart disease. 

·         Congenital heart disease. 

·         Electrical problems in the heart. 

Risk factors

·         A family history of coronary artery disease

·         Smoking

·         High blood pressure

·         High blood cholesterol

·         Obesity

·         Diabetes

·         A sedentary lifestyle

·         Drinking too much alcohol (more than one to two drinks a day)

Other factors that may increase your risk of sudden cardiac arrest include:

·         A previous episode of cardiac arrest or a family history of cardiac arrest

·         A previous heart attack

·         A personal or family history of other forms of heart disease, such as heart rhythm disorders, congenital heart defects, heart failure and cardiomyopathy

·         Age — the incidence of sudden cardiac arrest increases with age, especially after age 45 for men and age 55 for women

·         Being male — men are two to three times more likely to experience sudden cardiac arrest

·         Using illegal drugs, such as cocaine or amphetamines

·         Nutritional imbalance, such as low potassium or magnesium levels

Investigations 

Electrocardiogram

Blood tests

Blood tests may include:

·         Cardiac enzyme test. Certain heart enzymes leak into your blood if your heart has been damaged by a heart attack.

·         Electrolyte test. A sample of your blood may also be tested for levels of electrolytes, such as potassium, calcium and magnesium. Electrolytes are minerals in your blood and body fluids that help create electrical impulses.

·         Drug test. 

·         Hormone test. Testing for hyperthyroidism may indicate this condition as the trigger for your cardiac arrest.

Imaging tests

·         Chest X-ray.  check the size and shape of your heart and its blood vessels.

·         Echocardiogram.  An echocardiogram can help identify whether an area of your heart has been damaged by a heart attack and isn't pumping normally or at peak capacity (ejection fraction) or whether there are valvular abnormalities.

·         Ejection fraction testing. 

·         Nuclear scan. (Heartorg, 2015)

Other tests

Other tests that are often done include:

·         Electrical system (electrophysiological) testing and mapping. 

·         Coronary catheterization (angiogram). 

Immediate action for survival.

CPR

Immediate cardiopulmonary resuscitation (CPR

Advanced care for ventricular fibrillation

Management

·         Drugs. Doctors use various anti-arrhythmic drugs for emergency or long-term treatment of arrhythmias or potential arrhythmia complications. A class of medications called beta blockers is commonly used in people at risk of sudden cardiac arrest. Other possible drugs include angiotensin-converting enzyme (ACE) inhibitors, calcium channel blockers or a drug called amiodarone (Cordarone).

As with any medication, anti-arrhythmic drugs may have potential side effects. For example, an anti-arrhythmic drug may cause your particular arrhythmia to occur more frequently — or even cause a new arrhythmia to appear that's as bad as or worse than your pre-existing condition.

·         Implantable cardioverter-defibrillator (ICD) An ICD is a battery-powered unit that's implanted near your left collarbone. One or more electrode-tipped wires from the ICD run through veins to your heart.

·         Coronary angioplasty

·         Coronary bypass surgery

·         Radiofrequency catheter ablation. This procedure may be used to block a single abnormal electrical pathway. In this procedure, one or more catheters are threaded through your blood vessels to your inner heart. They're positioned along electrical pathways identified by your doctor as causing your arrhythmia. Electrodes at the catheter tips are heated with radiofrequency energy. This destroys (ablates) a small spot of heart tissue and creates an electrical block along the pathway that's causing your arrhythmia. Usually this stops your arrhythmia.

·         Corrective heart surgery

·         Heart transplantation

(Uptodatecom, 2015)

References

Heartorg. 2015. Heartorg. [Online]. [28 April 2015]. Available from: http://www.heart.org/HEARTORG/Conditions/More/CardiacArrest/About-Cardiac-Arrest_UCM_307905_Article.jsp

Uptodatecom. 2015. Uptodatecom. [Online]. [27 April 2015]. Available from: http://www.uptodate.com/contents/overview-of-sudden-cardiac-arrest-and-sudden-cardiac-death

Uptodatecom. 2015. Uptodatecom. [Online]. [27 April 2015]. Available from: http://www.uptodate.com/contents/post-cardiac-arrest-management-in-adults

Mayoclinicorg. 2015. Mayoclinicorg. [Online]. [27 April 2015]. Available from: http://www.mayoclinic.org/diseases-conditions/sudden-cardiac-arrest/basics/symptoms/con-20042982