ECG Questions

What change can occur on an ECG due to a coronary artery disease?

depressed ST segment and an inverted T wave

Q-T interval

The Q-T interval is the time interval from the beginning of the ventricular depolarization to the end of repolarization of the ventricles.

How high should the standardization mark be when the electrocardiogram is standardized?

10mm high and 2mm wide

How many leads are included in a standard electrocardiogram?

12

At what speed does the paper move while recording normal electrocardiogram?

25 mm/sec

What is the difference between a three-channel and a single-channel electrocardiograph?

A three channel can record the electrical activity of the heart through three leads simultaneously A single channel record only one lead at a time

What is the purpose of an interpretive capability?

Analyzes the recording as it being run with a built-in computer program.

Why should artifacts be eliminated if they occur in an ECG recording?

Because artifacts affects the quality of the recording making it difficult to manually measure the ECG cycle; can also cause a false positive result on an ECG that is analyzed by a computer.

Why does atrial repolarization not appear as a separate wave on the ECG cycle?

Because it occurs at the same time as ventricular depolarization.

Why is the baseline flat following the U wave?

Because no electrical activity is occurring.

Why must an electrolyte be used when recording an electrocardiogram?

Because the skin is a poor conduction the electrolyte is used between the electrode and the skin to facilitate the transmission.

What is the name of the device placed on the skin to pick up electrical impulses?

Electrode

What is the purpose of an EMR connectivity?

Electronic medical record- allow the ECG machine to be linked with the office computer system.

List examples of cardiac dysrhythmias.

Extra beats Abnormal rhythm Abnormal heart rate

What is the purpose of the standardization mark?

I shows voltage.

Standard leads

I, II, III Record differences between arm and legs. Considered bipolar leads Have 12 leads in an ECG

What is a lead, and what information does it provide?

Is a tracing of the electrical activity of the heart between two electrodes. Provides an electrical "photograph" of the heart's activity from a different angle to provide a thorough interpretation of the heart's activity.

List three possible causes of 60-cycle interference artifacts.

Lead wires not following the body contour Other electrical equipment in the room Wiring in the walls, ceiling or floors Improper grounding of the ECG

List three possible causes of wandering baseline.

Lose electrodes Dried out electrolyte Body creams, oils or lotions Excessive movement of the chest

What is the function of an electrode?

Measure and record the electrical activity generated by the heart and carried through the body. (Pick up the electrical impulses given off by the heart and conduct them through lead wires)

What is the cardiac cycle?

One complete heartbeat

List three possible causes of muscle artifacts.

Patient discomfort Patient movement Physical condition Apprehensive (anxious) patient

What is the function of an artifact filter?

Reduce artifacts when all else false but also affects the results.

How can you identify a muscle artifact on an electrocardiogram tracing?

Small, jagged peaks of various heights and large, erratic spikes

How many electrodes are usually used to take a 3-channel ECG?

Ten (10)

P wave

The P wave represents the electrical activity associated with contraction of the atria, or atrial depolarization.

P-R interval

The P-R interval represents the time interval from the beginning of the atrial depolarization to the beginning of the ventricular depolarization.

P-R segment

The PR segment represents the time interval from the end of the atrial depolarization to the beginning of the ventricular depolarization. It is the time needed for the impulse to be delayed at the AV node and then travel through the bundle of His and Purkinje fibers to the ventricles.

QRS Complex

The QRS complex represents the electrical activity associated with the contraction of the ventricles, or ventricular depolarization.

S-T segment

The ST segment represents the time interval from the end of the ventricular depolarization to the beginning of repolarization of the ventricles.

T wave

The T wave represents the electrical recovery of the ventricles, or ventricular repolarization. The muscle cells are recovering in preparation for another impulse.

What is the purpose of standardizing the electrocardiograph?

The purpose of standardizing the ECG is to enable a physician see the height of a standard deflection and whether the machine is properly calibrated.

When you are taking an electrocardiogram, which statement regarding the standard leads is true?

The standard leads are recorded from electrodes placed on the arms and legs.

Why is the R wave taller than the P wave on the ECG graph cycle?

The ventricles are larger than the atria and therefore require a long electrical stimulus to depolarize the ventricle.

When you are taking an electrocardiogram, what do the augmented leads measure?

The voltage potential at one extremity (right arm, left arm, or left leg)

List four uses of Holter monitor electrocardiography.

To assess the rate and rhythm of the heart during daily activities To evaluate patients with unexplained chest pain, dizziness, or syncope To discover intermittent cardiac dysrhythmias not picked up on a routine resting 12-lead ECG To detect myocardial ischemia To assess the effectiveness of antidysrhythmic medications To assess the effectiveness of a pacemaker.

What is the purpose of a teletransmission?

Transmit a recording performed at the medical office electronically to an ECG data interpretation site.

Precordial leads

V1, V2,V2, V3, V4, V5, V6 In front of the heart Record the voltage from the back to the front of the heart

Augmented leads

aVR(right), aVL(left), aVF(foot) Record two differences between 1 positive and 2 negatives electrodes Considered unipolar

What change can occur on an ECG due to a myocardial infarction?

larger Q wave and an elevated ST segment

What is the purpose of electrocardiography?

measures and provide a visual record of the electrical activity of the heart