Treatments for Sudden Cardiac Arrests

The arrhythmias that occur when a Sudden Cardiac Arrest (SCA) occurs are: ventricular fibrillation (VF)/ventricular tachycardia (VT) the heart fails to pumps adequate amounts of blood, Asystole: the cessation of heart beats, or pulse less electrical activity (PEA): the heart should be producing a pulse, but is not.

In the case of VF/VT, defibrillation terminates the arrhythmia by depolarizing a critical mass of the heart muscle, thus allowing a normal sinus rhythm to be established. When the time to defibrillation is less than 2 minutes, the patient has an 80% chance of being successfully resuscitated. However, prolonged arrest intervals forces the body to deplete its stores of oxygen and high-energy adenosine triphosphate (ATP), nutrients necessary for re-establishing a normal perfusing rhythm. Consequently, a victims chance of surviving a SCA decrease by 10 to 15% for every minute of arrest with a dismal chance of resuscitation occurring at 10 minutes.



In the case of Asystole or PEA, the treatment is intravenous delivery of Epinephrine along with high quality CPR. Defibrillation is NOT used in these arrests as the problem lies in the response of the Myocardial tissue to electrical impulses.

Another approach that researchers have begun to embrace a concept first pioneered and published by Dr. James Niemann of Harbor-UCLA in 1992 where a period of CPR in animals prior to attempting defibrillation in prolonged was shown to improve outcomes. Recently, several large studies have been published that have demonstrated a significant increase in survival rates as a result of CPR prior to defibrillation in arrests of greater than four minutes.



Manual CPR was developed to prolong the treatment window of a person whose heart has stopped. The theory was that blood flow could be generated by physically pushing the sternum 1.5 to 2 inches into the chest, thereby compressing the chambers of the heart between the sternum and the spine. Trauma is almost always induced as the chest is subjected to a repetitive, focused force on the center of the sternum. The effectiveness of manual CPR is influenced by the following factors: location of the patient, the physical size and weight of both the patient and the rescuer, the training, experience and physical and emotional state of the rescuer. Under ideal conditions, manual CPR produces 15% of normal blood flow. Unfortunately, survival rates for those that recevive less than 15% are quite low.