2 Heart Rate and Rhythm Assessment Free Online FlashCards

What time does each ECG grid square represent at 25 mm/s?

At a paper speed of 25 mm/s, each small square represents 0.04 seconds and each large square represents 0.20 seconds.

How do you estimate the rate from an irregular 10-second rhythm strip?

Count the QRS complexes in 10 seconds and multiply by 6. For 13 complexes, the average rate is about 78 beats/min.

What do equal R–R intervals indicate?

Equal R–R intervals indicate regular ventricular timing; visibly varying R–R intervals indicate irregular timing.

What does the PR interval measure, and what is its usual adult range?

The PR interval runs from the start of the P wave to the start of the QRS complex. The usual adult reference range is 0.12–0.20 seconds.

Which ECG waveform represents ventricular depolarization?

The QRS complex represents ventricular depolarization.

What is the common cutoff between narrow and wide QRS duration?

A QRS duration under 0.12 seconds is commonly described as narrow; 0.12 seconds or longer is wide.

What does a consistent P–QRS–T sequence suggest about the observed events?

A similar P wave followed by a QRS and then a T wave shows a consistent observed sequence of atrial and ventricular events. Describe the pattern shown rather than assuming more than the tracing supports.

What is a QT interval spanning 10 small squares, and what affects its interpretation?

At 25 mm/s, 10 small squares equal 0.40 seconds. Because QT varies with heart rate, interpret it with rate in mind, typically by considering QTc.

What features should a structured rhythm-strip assessment include beyond rate?

Assess P–P and R–R regularity, P-wave presence and consistency, whether each P is followed by a QRS, PR interval, QRS width and shape, and T-wave sequence and appearance.

Why is one R–R interval a poor rate estimate for an irregular rhythm?

A single R–R interval may not represent the average rate when intervals vary. Use a QRS count over a timed strip instead.

What electrical event does the P wave represent?

The P wave represents atrial depolarization.

What electrical event does the T wave represent?

The T wave represents ventricular repolarization.