3 Ventricular Rhythms and Conduction Disorders Free Online FlashCards

What should you assess before interpreting an ECG rhythm?

Assess responsiveness, pulse, blood pressure, perfusion, breathing, and symptoms first; a rhythm label does not replace clinical assessment.

What are the normal PR and narrow-QRS thresholds?

A normal PR interval is $0.12$–$0.20\,\text{s}$. A QRS is narrow below $0.12\,\text{s}$ and wide at or above $0.12\,\text{s}$.

What ECG pattern identifies a premature ventricular complex?

A PVC is an early, wide, usually bizarre QRS without a preceding sinus P wave, often followed by a compensatory pause.

How does accelerated idioventricular rhythm compare with an escape rhythm and VT?

Accelerated idioventricular rhythm is a repeating ventricular rhythm faster than an escape rhythm but slower than most VT. It can be transient, including during reperfusion.

What is the key ECG pattern of monomorphic VT?

Monomorphic VT is usually a regular wide-complex tachycardia with a consistent QRS shape. In an adult, treat unexplained wide-complex tachycardia as VT until proven otherwise.

What distinguishes torsades de pointes, and how is sustained polymorphic VT shocked?

Torsades de pointes is polymorphic VT that appears to twist around the baseline and is associated with prolonged QT. Sustained polymorphic VT requires an immediate unsynchronized shock.

What is the immediate response to pulseless VT or VF?

Pulseless VT and VF require immediate CPR and unsynchronized defibrillation according to the current resuscitation algorithm.

What is generally indicated for unstable tachyarrhythmia with a pulse?

Unstable tachyarrhythmia with a pulse generally requires prompt synchronized cardioversion.

How does Mobitz I AV block progress?

In Mobitz I, the PR interval progressively lengthens until a P wave is not followed by a QRS; the cycle then repeats.

Can a 2:1 AV block pattern alone identify Mobitz I or II?

A 2:1 AV block means every other P wave is blocked. The pattern alone usually cannot distinguish Mobitz I from Mobitz II, so do not assign a type from it alone.

What ECG relationship defines third-degree AV block?

In complete AV block, P waves and QRS complexes occur independently, with no consistent PR relationship; a slower escape rhythm maintains ventricular activity.

What do capture and failure to capture look like on an ECG?

A pacing spike followed by the expected chamber response indicates capture. If a spike is not followed by the expected P wave or QRS, this is failure to capture.