EKG and Cardiac Rhythm Review

These flashcards cover key concepts related to EKG interpretation, heart rhythms, and important definitions.

What does an EKG record?

The electrical activity of the heart, not the mechanical squeeze.

What is a P wave in an EKG?

Atria depolarize.

What does the QRS complex indicate?

Ventricles depolarize.

What does the QT interval measure?

Total time from ventricular depolarization to ventricular repolarization.

How long is a normal PR interval?

0.12–0.20 seconds, equivalent to 3–5 small boxes.

What suggests wide QRS complexes?

Abnormal ventricular conduction, such as a bundle branch block.

What is normal sinus rhythm?

SA node controls the heart normally, with a rate of 60–100 bpm.

What characterizes sinus bradycardia?

Sinus rhythm with heart rate <60 bpm.

What is the difference between Mobitz I and Mobitz II?

Mobitz I shows progressive PR prolongation, while Mobitz II has fixed PR with intermittent dropped QRS.

What typically necessitates the use of a pacemaker?

Mobitz II, third-degree AV block, or symptomatic sinus bradycardia.

What ECG clue indicates right atrial enlargement?

Tall, peaked P waves in lead II.

What causes left axis deviation?

Conditions like left ventricular hypertrophy, right or inferior MI, and left anterior hemiblock.

How is heart rate calculated for irregular rhythms?

Using the 6-second method: count QRS complexes in 6 seconds and multiply by 10.

What indicates right bundle branch block in an EKG?

Wide QRS and rSR′ pattern in V1.

What is an important treatment for symptomatic sinus bradycardia?

Atropine.

What are the normal axis values in an EKG?

0° to +90° with a small allowance to roughly –15° to +105°.