Ventricular Fibrillation and role of Cardiopulmonary resuscitation

Posted by e-Medical PPT Sunday, May 5, 2013
What is SCD ( Sudden Cardiac Death ) ?
SCD must be defined carefully
Sudden cardiac death is defined as unexpected death, occurring within 1 hour from the onset of symptoms, that is not directly attributable to other factors.
It is the leading cause of mortality in industrialized nations, accounting for 12% of all natural deaths and 50% of all deaths attributable to cardiovascular disease

The immediate cause leading to the final common pathway of total hemodynamic collapse is most frequently ventricular tachycardia (VT) and ventricular fibrillation (VF); asystole, pulseless electrical activity, aortic rupture, and cardiac tamponade account for the remainder

-The proximate events leading to these fatal ventricular arrhythmias result from a wide spectrum of underlying disease states, mediated by physiologic and environmental triggers.

What is VF ?
VF is the primary cause of sudden cardiac death (SCD). Ventricular fibrillation (VF) is the most commonly identified arrhythmia in cardiac arrest patients.
I is a rapidly fatal rhythm and if resuscitation is not begun within 5 to 7 minutes , death is virtually  certain .
 The heart consequently immediately loses its ability to function as a pump.

As the initial reentrant pattern of excitation breaks up into multiple smaller wavelets, the level of disorganization increases.
 Sudden loss of cardiac output with subsequent tissue hypoperfusion creates global tissue ischemia; brain and myocardium are most susceptible.
If the fibrillatory waves are large the arrhythmia is described as course ventricular fibrillation.
Fibrillation waves which are greater than 3mm in height
Course VF indicates a more recent onset and is more likely to be reversed by defibrillation alone
If the fibrillatory waves are small the arrhythmia is described as fine ventricular
Fibrillation waves which are smaller than 3mm in height.
Fine VF indicates the arrhythmia has been present longer and may, before require drug therapy first, then defibrillationre the arrhythmia  can be reversed. Fine reversed.
 Fine ventricular fibrillation can progress to asystole if left untreated.

What is VT( ventricular tachycardia )
An arrhythmia originating in an ectopic focus in the bundle, Purkinje network, or ventricular myocardium
Series of wide QRS complexes firing at a rapid rate (minimum of three or more consecutive premature ventricular contractions)
Impulses originating from ventricular tissue do not produce P

What is Asystole ?
Asystole is the absence of electrical activity in the myocardium. “Flat line” possible causes : - Power off - Lead not attached - Lead selection -Fine VF (Rare) -asystole

How do you Confirm the Rhythm in Asystole ?
Confirm rhythm in two leads
Always check your leads are attached

Should you Defibrillate Asystole ?
Be sure to check in two leads that the rhythm is not “Fine” VF. - In this case you would follow the V-Fib algorithm
No evidence that defibrillation is beneficial
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