Cardiac arrest

Definition :

                Cardiac arrest describes the sudden and complete loss of cardiac output due to abnormal electrical activity such as  asystole (absence of ventricular contraction),ventricular tachycardia or fibrillation or loss of mechanical cardiac contraction (pulse less electrical activity)

Normal mechanism :

                The heart has an electrical system that controls the rate and rhythem of the heartbeat.If there is a problem in the electrical signaling of the heart it beats uncontrolabley and in unrhythemic pattern called arrhythemia.

                             A common arrhythmia associated with cardiac arrest is ventricular fibrillation. Ventricular fibrillation means that the heart’s lower chambers suddenly start beating chaotically(confused manner) and don’t pump blood

Epidimiology :

              The lifetime risk of cardiac arrest is three times more in Men then in Women

Etiology :

Coronary artery disease (85%) :            

• Acute Myocardial infarction
• Myocardial ischemia

Structural heart disease (10%) :

• Aortic stenosis
• Hypertrpertrophic cardiomyopathy
• Dilated cardiomyopathy
• Congenital heart disease

No structural heart disease (5%) :

•    Long QT syndrome (problem in pores on surface of heart muscle cell cause                   disorders in electrical activity)    
•    Brugada syndrome (genetic disorder-abnormal electrical activity)
•    adverse drug rections
•    Sever electrolyte imbalance
•     intense physical activity (trigger adernaline release -trigger cardiac arrest in patient with heart problems )

Non cardiac reversible cause :

Mnemonic for reversible causes

"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 increased or decreased potassium can be life-threatening.
• Hypothermia – A low core body temperature
• Hypoglycemia or Hyperglycemia – Low or high blood glucose

Ts

• Tablets or Toxins such as drug overdose
• Cardiac Tamponade – Fluid building up 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 - due to blunt or penetrating injury

 Risk factors :

• Aged persons
• being men
• people with ischemic heart disease diagnosed
• History of arrhythemias
• drug or alcohol abuse
• heart failure patients                                

Pathophysiology :

Cardiac arrest VS Heart attack :

Clinical feauture :

• Loss of conciousness
• Loss of pulse
• Loss of breathing

some peoples may experience warning signs such as 

• feel dizy or light headdedness
• Chest pain
• shortness of breath
• nausea (feeling sick in stomach) or vomiting

while most of cardiac arrest occurs suddenly

Diagnosis :

            Sudden cardiac arrest (SCA) happen with or without worning signs and it requires emergency treatement.

             SCA is often diagnosed after it happens to rule out the cause

1.ECG : 

• Shows evidence of heart damage due to ischemic heart diseases
•  shows signs of previous or current heart attack
  

2.Echocardiography:

• identify areas of poor blood flow
• identify areas of heart muscle not working
  

3.Multiple gatedacqiuistion test (MUGA) :

• Small amount of radioactive substance is injected into a vein and travel to heart
• the substance release energy which can detected by camera outside the body and make pictures
• it helps to find how well the ventricles pumping out

4.MRI :

• to look for the structure and function of the heart
• gives detailed pictuere of heart

MRI OF POST MYOCARDIAL INFARCTION

5. CARDIAC CATHETRAZATION:

                        this procedure is used to diagnose and treat or remove blokage.

in coronary artery

                             

 6. BLOOD TEST:

                to examine level of potassium and magnesium in blood (they are important in heart electrical signaling)

Treatment :

When a patient with suspected cardiac arrest is encountered, the ABCDE approach to management should be fallowed 

A-  Airway maintence 

B-  Breathing (mouth to mouth) 

C- maintenence of Circulation (Chest compression)

D- Disability management(In resuscitated patient for assessment of neurological      management) 

E- Exposure (removal of cloths to enable defibrillation)

Defibrillation :

                        Defibrillation is a technique used in emergency medicine to terminate ventricular fibrillation or pulseless ventricular tachycardia. It uses an electrical shock to reset the electrical state of the heart so that it may beat to a rhythm controlled by its own natural pacemaker cells.

1.BASIC LIFE SUPPORT : (outside hospital)

                The term basic life support(BSL) refers to encompasses manover that aim to maintain a low level of circulation untill health care professionals arives.

Add AED-Automated external defibrillator
 shockable rhythms (ventricular fibrillation/pulseless ventricular tachycardia (VF/pVT)) 
 non-shockable rhythms (asystole and pulseless electrical activity (PEA)

3.ADVANCED LIFE SUPPORT : (in hospital)

        Its aim to restore normal cardiac rhythem by defibrillation

        First the patient is attached to defribrillator or monitor

        treatment is intiated based on clinical findings   

 

4.POST CARDIAC ARREST TREATMENT :

                        Stabilize the patient

                        treating reversible cause (Hs and Ts)

5.CHAIN OF SURVIVAL :

4.LONGTERM MANAGEMENT:

            

                Drugs: betablockers ,ACE inhibitor,Calcium channel blockers

5.SURGERY :

   

    -Coronary angioplasty:

• A coronary angioplasty is a procedure used to widen blocked or narrowed coronary arteries (the main blood vessels supplying the heart).
• The term "angioplasty" means using a balloon to stretch open a narrowed or blocked artery.

    -Coronary bypass surgery :

            A coronary artery bypass graft (CABG) is a surgical procedure used to treat coronary heart disease.It diverts blood around narrowed or clogged parts of the major arteries to improve blood flow and oxygen supply to the heart.

    -Cardiac ablation :

            Cardiac ablation is a procedure to scar or destroy tissue in your heart that's allowing incorrect electrical signals to cause an abnormal heart rhythm

        -Corrective heart surgery: in case of heart abnormality such as congenital heart diseases,aortic stenosis

Prevention:

Implantable cardioverterdefribillator (ICD)

• reduces the chances of dying from a second SCA. An ICD is surgically placed under the skin in your chest or abdomen. The device has wires with electrodes on the ends that connect to your heart's chambers. The ICD monitors your heartbeat.
• If the ICD detects a dangerous heart rhythm, it gives an electric shock to restore the heart's normal rhythm