Ventricular Fibrillation and Pulseless Ventricular Tachycardia

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Ventricular fibrillation (VF) and pulseless ventricular tachycardia (VT) are life-threatening cardiac rhythms that result in ineffective ventricular contractions. VF (Figure 24) is a rapid quivering of the ventricular walls that prevents them from pumping. The ventricular motion of VF is not synchronized with atrial contractions. VT (Figure 25) is a condition in which the ventricles contract more than 100 times per minute. The emergency condition, pulseless VT, occurs when ventricular contraction is so rapid that there is no time for the heart to refill, resulting in undetectable pulse. In both cases, individuals are not receiving adequate blood flow to the tissues. Despite being different pathological phenomena and having different ECG rhythms, the ACLS management of VF and VT are essentially the same. Resuscitation for VF and pulseless VT starts with the BLS Survey.

An AED reads and analyzes the rhythm and determines if a shock is needed. The AED is programmed to only prompt the user to shock VF and VT rhythms. The machine does not know if the individual has a pulse or not. This is the primary reason you should not use an AED in someone with a palpable pulse. ACLS responses to VF and pulseless VT within a hospital will likely be conducted using a cardiac monitor and a manual defibrillator. Thus, the ACLS provider must read and analyze the rhythm. Shocks should only be delivered for VF and pulseless VT. Likewise, antiarrhythmic drugs and drugs to support blood pressure may be used.

Rules for Ventricular Fibrillation (RF)

ACLS Ventricular Fibrillation rhythm

Figure 24

Regularity There is no regularity shape of the QRS complex because all electrical activity is disorganized.
Rate The rate appears rapid but the disorganized electrical activity prevents the heart from pumping.
P Wave There are no P waves present.
PR Interval There are no PR Interval present.
QRS Complex The ventricle complex varies

Table 5

Rules for Ventricular Tachycardia

(Regular/Rapid Wide Complex Tachycardia)

ACLS Ventricular Tachycardia rhythm

Figure 25

Regularity R-R intervals are usually, but not always, regular. RATE
Rate The atrial rate cannot be determined. Ventricular rate is usually between 150 and 250 beats per minute.
P Wave QRS complexes are not preceded by P waves. There are occasionally P waves in the strip, but they are not associated with the ventricular rhythm.
PR Interval PR interval is not measured since this is a ventricular rhythm.
QRS Complex QRS complex measures more than 0.12 seconds. The QRS will usually be wide and bizarre. It is usually difficult to see a separation between the QRS complex and the T wave.

Table 6

Rules for Torsades De Pointes

(Irregular Wide Complex Tachycardia)

ACLS Torsades de Portes Rhythm

Figure 26

Regularity There is no regularity.
Rate The atrial rate cannot be determined. Ventricular rate is usually between 150 and 250 beats per minute.
P Wave There are no P waves present.
PR Interval There are no PR intervals present.
QRS Complex The ventricle complex varies.

Table 7

Take Note

VF and pulseless VT are both shockable rhythms. The AED cannot tell if the individual has a pulse or not.

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