ECG

What Is The Normal QRS Duration

0.06 to 0.12 Seconds

When Does A Widened QRS Occur

Can occur with conditions where the impulse formation occurs in the ventricles, such as premature ventricular complexes (PVC) and ventricular tachycarida.

What Are Prolonged PR Intervas Associated With

First degree AV blocks and with digoxin toxicity; indicates that the impulse is delayed as it passes through the AV node

How Is The T Wave Measured

Follows the QRS complex and the ST segment. Normally is rounded and smooth.

What Is The Importance Of PR Interval For ECG Interpretation

Helps signal the presence of a conduction delay disturbance such as an AV blcok

What Does A Peaked T Wave Indicate

Hyperkalemia

What Is The Q Wave

If the first deflection is negative, it is called a Q wave. Not everyone has Q waves

What Is The Importance Of The QRS Complex

Interpretation is critiical because of its impoprtance in feflecting ventricular myocardial cell activity. The QRS complex represents ventricular depolarization. so ventricular contraction can be assumed

What Are Short PR Intervals Associated With

Junctional rhythms and indicate that the impulse originated in an area other than the SA node

Where Is The P Wave Located And What Does It Look Like

Located before the QRS complex; Normally upright and rounded; Should be upright in lead II

How Is The PR Interval Measured

Measured from beginning of P wave to beginning of QRS complex.

How Is The QRS Complex Measured

Measured from the beginning of the complex to the end of the complex

How Is The ST Segment Measured

Measured from the end of the S wave to the beginning of the T wave. The deflection should be isoelectric, but may vary 1mm or less

What Does An Inverted T Wave Indicate

Myocardial Ischemia

What Is The PR Interval Duration

Normal Duration is 0.12 to 0.20 seconds

When Do QRS Configuration Variations Occur

Occur with intraventricular conduction delays (IVCD) such as bundle branch blocks

What Do Heavily Notched T Waves Indicate

Pericarditis in adults, but are normal in children

What Does The ST Segment Represent

Represents the time between ventricular depolariation and repolarization (diastole).

What Does A P Wave Represent

Represents time for the passage of the electrical impulse through the atrium causing atrial depolarization (contraction).

What Does The T Wave Represent

Represents time for ventricular repolarization

What DoesThe QRS Complex Represents

Represents time taken for depolarization (contraction) of ventricles (systole).

What Does The PR Interval Represent

Represents time taken for impulse to spread through the atria, AV node and bundle of His, the bundle branches, and Purkinje fibers, to a point Immediately preceding ventricular contraction. This is the time from the beginning of atrial depolarization to the beginning of ventricular depolarization

What Does A ST Segment Depression Indicate

Segment depression (2mm or more below the baseline) may indicate an old myocardial ischemia. Other changes may be seen with pericarditis, pulmonary emboli and electrolyte distrubances.

What is The S Wave

The first negative deflection after the R wave

What Is The R Wave

The first positive deflection. Often is the first waveform after the PR interval

What Is The Importance Of The T Wave

The peak of the T wave represents the vulnerable period of repolarization. This is the period of time when the ventricles are most susceptible to extra stimuli

What Is The Importance Of The P Wave For ECG Interpretation

The presecne of a Pwave indicates that the impulse originated in either the SA node, the atria, or the AV junction tissue. If the P wave is normal, it is referred to as a sinus P wave, meaning that it originated in the SA node.