Cardiac arrest & Sudden cardiac death

Cardiac arrest & Sudden cardiac death

Cardiac arrest describe the sudden and complete loss of cardiac output due to asystole , ventricular tachycardia or ventricular fibrillation, or loss of mechanical cardiac contraction (pulsess electrical activity).

Cardiac arrest, also known as cardiopulmonary arrest or circulatory arrest, is the cessation of normal circulation of the blood due to failure of the heartto contract effectively. Medical personnel may refer to an unexpected cardiac arrest as a sudden cardiac arrest (SCA).A cardiac arrest is different from (but may be caused by) a heart attack, where blood flow to the muscle of the heart is impaired.

Sudden cardiac death is usually caused by a catastrophic arrhythmia and accounts for 25-30% of deaths from cardiovascular disease.

Common causes:

1.      Coronary artery disease (85%):

·         Myocardial ischemia.

·         Acute MI.

·         Prior MI with myocardial scarring.

2.      Structural heart disease (10%):

·         Aortic stenosis.

·         Hypertrophic cardiomyopathy.

·         Dilated cardiomyopathy.

·         Arrhythmogenic right ventricular dysplasia.

·         Congenital heart disease.

3.      No structural heart disease:

·         Long QT syndrome.

·         Brugada syndrome.

·         Wolf-Parkinson-White syndrome.

·         Adverse drug reactions (torsades de pointes)

·         Severe electrolyte abnormalities.

Etiology:

1.      Ventricular fibrillation (common):

·         MI or electrocution.

·         Myocarditis, cardiomyopathy.

·         Electrolytes imbalance (such as hypokalaemia)

·         Ventricular arrhythmias.

2.      Ventricular asystole:

·         Complete heart block.

·         Massive ventricular damage.

3.      Electromechanical dissociation:

·         Hypovolaemia.

·         Tension pneumothorax.

·         Cardiac rupture.

·         Massive pulmonary embolism.

Risk factors:

The risk factors for SCD are similar to those seen with coronary heart disease including:smoking, lack of physical exercise, obesity, diabetes, and family history.

Hs and Ts

Main article: Hs and Ts

"Hs and Ts" is the name for a mnemonic used to aid in remembering the possible treatable or reversible causes of cardiac arrest.

Hs

• Hypovolemia - A lack of blood volume
• Hypoxia - A lack of oxygen
• Hydrogen ions (Acidosis) - An abnormal pH in the body
• Hyperkalemia or Hypokalemia - Both excess and inadequate potassium can be life-threatening.
• Hypothermia - A low core body temperature
• Hypoglycemia or Hyperglycemia - Low or high blood glucose

Ts

• Tablets or Toxins
• Cardiac Tamponade - Fluid building around the heart
• Tension pneumothorax - A collapsed lung
• Thrombosis (Myocardial infarction) - Heart attack
• Thromboembolism (Pulmonary embolism) - A blood clot in the lung
• Traumatic cardiac arrest

Clinical features:

Symptoms:

1.      Loss of consciousness.

2.      Cessation of respiration.

3.      Coldness of the extremities.

Signs:           

1.      No pulse.

2.      No BP.

3.      No heart sound.

4.      Dilated fixed pupils.

5.      Death like appearance.

Principles of management of cardiac arrest:

1.      Maintenance of respiration.

2.      Maintenance of circulation.

3.      Treatment of underlying causes.

Management of cardiac arrest: First confirm the diagnosis. Next deliver a sharp blow to the center of the chest. If heart does not start immediately start basic life support.

[A]Basic life support (BLS): The management of collapsed patient requires prompt assessment and restoration of the airway, breathing and circulation with basic life support with the aim of maintaining the circulation until more definitive treatment with advance life support can be administered.

The ABC of basic life support:

(a)    Airway: Clear the airway of vomitus or debris, extend the neck and raised the chin.

(b)   Breathing:

·         Direct mouth to mouth breathing.

·         Indirect mouth to mouth breathing.

(c)    Circulation: Cardiac massage.

[B]Advances life support (ALS): ALS aims to restore the normal cardiac rhythm by defibrillation when the cause of cardiac arrest is due to tachyarrhythmia and or to restore cardiac output by correcting other reversible causes of cardiac arrest.ALS provides support to the circulation additional to BLS by administering i/v drugs and by passing an endotracheal tube to administer positive pressure ventilation.

v  Introduce endotracheal tube and ventilate the lung.

v  Obtain an ECG to determine the type:

a)      If cardiac arrest is due to ventricular fibrillation or pulseless ventricular tachycardia: Prompt defibrillate.

b)      If cardiac arrest is due to ventricular asystole:

·         If asystole is not confidently diagnosed: then the patient should be defibrillated.

·         If definite asystole: Treat without defibrillation by maintaining cardiopulmonary resusciatation.

Unresponsiveness?

↓

Shout for help

↓

Open airway

↓

Not breathing normally

↓

Call emergency services

↓

30 chest compressions

↓

2 rescue breath & 30 compressions

Fig: Algorithm for adult basic life support

Reference:

1.      Davidson’s Principle and Practice of Medicine, 21^st edition.

2.      Wikipedia the free encyclopedia.

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