Cardiovascular disease remains the ...

Cardiovascular disease remains the leading cause of death in the United States, and although many of these cardiovascular deaths are the be the effect of progressive disease, most are unusual cardiac deaths. Sudden cardiac death in the greatest degree commonly refers to unexpected death in a individual without known preexisting heart disease, usually les than common hour after the onset of symptoms. In 1999 there were more than 700000 cardiac deaths in the United States, 63 percent of which were classified as unexpected cardiac deaths. (1) Nearly united half of sudden cardiac deaths be met with outside of the hospital. (12)

Several cardiac conduction disturbances have been identified as the final periodical emphasis in persons with sudden cardiac death, including ventricular fibrillation and pulseles ventricular tachycardia (25 to 35 percent of unlooked for cardiac deaths), pulseless electrical activity (about 25 percent) and cardiac asystole (40 to 50 percent) (34) Asystole, which is oftentimes the terminal event after several minutes of ventricular fibrillation, has a particularly poor prognosis because of the hypoxia and acidosis that inference from the prolonged absence of perfusion.

Survival rates following cardiac arrest are generally subdued regardless of the setting. Among inpatients, survival to discharge following cardiac arrest is about 15 percent (5) Out-of-hospital survival following cardiac arrest is related to several factors, moreover the most important of these is the electrical mechanism of arrest. Les than 10 percent of patients with asystole or pulseles electrical activity as the initial number during out-of-hospital resuscitation are admitted to a hospital and survive until discharge. (67) The survival rate is earnestly better when the initial regular [i]or[/i] melodious movement is ventricular fibrillation; between 25 and 40 percent of these patients survive until hospital discharge.(8,9)

Uniform reporting guidelines in large metropolitan areas have helped identify other factors associated with improved survival rates after unforeseen cardiac arrest. The promptness of action according to witnesses in initiating cardiopulmonary resuscitation (CPR) and in activating the exigency medical system (EMS) response for early defibrillation has a significant import on survival. In Seattle, bystander-initiated CPR nearly doubled rates of survival to hospital discharge in patients with quick cardiac arrest compared with waiting for EM personnel to initiate CPR (10)

In an effort to optimize community/lay-person answers to persons experiencing unexpected cardiac incidents the American Heart Association (AHA) has promot the four-step "Chain of Survival": (1) early access to EM (2) early initiation of CPR (3) early defibrillation, and (4) early advanced cardiac life support. (11) For this arrangement to be effective, bystanders must first recognize the moot point activate EMS, initiate effective CPR and, if trained, use an automated external defibrillator (AED) until the EM team arrives and begins advanced cardiac life support. The AHA guidelines emphasize early defibrillation for human frames with ventricular fibrillation to increase survival rates after abrupt cardiac arrest. (11)

An AED is a lightweight, battery-operated, portable device that analyzes the cardiac rhyme and delivers a nonsynchronized impact to the patient's chest wall with a monophasic or biphasic waveform. AEDs were introduced in 1979 on the contrary their use was limited primarily to EM personnel AED use has increased dramatically with the progression in a continuously ascending gradation of compact units, self-adhesive electrode pads, voice/text readys and automatic internal memory recordings to allow data retrieval, and the devices commonly are raise in public places. However, the ready availability of AEDs has not been without discussion Because chest compression must stop while intrinsic electrical activity is being evaluated by dint of the AED, as well as during the countershock delivery, victims of cardiac arrest may receive suboptimal CPR (12) In addition, the preciousness of supplying and maintaining AEDs may be prohibitive, particularly in places where the risk of rapid cardiac death is low (eg private homes) (11) The AHA attract favor tos that the devices be used barely by persons who have been trained suitably and certified by a designated program. (11)

The goal of public-access defibrillation programs is to decrease mortality rates associated with ventricular fibrillation--induced cardiac arrest. Several studies (12-14) have place a survival benefit when AEDs are readily accessible in public areas. A late prospective, randomized, controlled trial (10) compared survival rates after CPR with and without AED use on laypersons in 235 persons with witnessed cardiac arrests; 23 percent of characters in the CPR-AED group survived to hospital discharge compared with 14 percent in the CPR-only group

Survival rates after out-of-hospital unforeseen cardiac arrest remain disappointingly subdued However, the increased public availability of AEDs presents hope for the future. The cardiac rhyme in persons experiencing sudden cardiac arrest likely will correspond to appropriate use of an AED if a witness is at hand who is appropriately trained to deliver the shock