Lab4 ECG Part I

Comprehensive flashcards covering the principles of electrocardiogram, including wave identification, lead placement, paper measurements, and cardiac physiology.

Which scientist named the prominent waves (P, Q, R, S, T) of the electrocardiogram alphabetically?

Einthoven

What are the two distinct phases of the cardiac cycle?

Systole and Diastole

What activity occurs in the atria and ventricles during the systole phase?

They contract and empty of blood.

What happens during the diastole phase of the cardiac cycle?

This is the relaxation phase when the heart chambers refill with blood.

What electrical event is represented by the P wave?

Depolarization of atria

What mechanical event is triggered by the depolarization of the atria?

Atrial contraction/systole

What electrical event does the QRS complex reflect?

Depolarization of ventricles

What mechanical event results from the depolarization of the ventricles?

Ventricular contraction/systole

Which components of the ECG reflect the repolarization of the muscle fibers in the ventricles?

The ST segment and the T wave

During which phase of the heart's mechanical cycle does ventricular repolarization occur?

Ventricular diastole

In the electrical sequence of events, what occurs immediately after SA node depolarization?

Atrial depolarization

What occurs after the AV node-His bundle transit in the sequence of cardiac electrical events?

RB and LB depolarization (R and L Bundle)

What is the final electrical event in the sequence before ventricular contraction?

Right and Left ventricle depolarization

How is the ECG stylus deflected if the cardiac current flows in the same direction as the axis of the lead?

Strongly upward from the baseline

What happens to the stylus deflection if current flows obliquely to the axis of the lead?

It is deflected less strongly upward, varying with the angle the vector makes with the axis.

What is the result on an ECG tracing if the current flow is perpendicular to the lead axis?

There is no deflection (no upward or downward movement) of the stylus.

How does the stylus respond when current flow is in the opposite direction to the axis of the lead?

It is deflected strongly downward.

What happens to the stylus if current flows obliquely in the opposite direction to the lead axis?

It is deflected less strongly downward, with depth varying by the angle.

What is the deflection of the stylus when there is no current flow?

There is no deflection of the stylus.

What is the term for the resting state of the myocardial wall where no electrical activity occurs?

Polarization

How is the state of polarization recorded on an ECG strip?

As a straight line

Which process results in the contraction of the simulated heart muscle?

Depolarization

What is the term for heart muscle cells returning to a resting state?

Repolarization

How is the P wave typically described in terms of its appearance on an ECG?

It is the first deflection from the baseline, typically smooth and rounded.

Is the repolarization of the atria normally recorded on a standard ECG strip?

No

What is the PR segment defined as?

The return to the baseline after atrial contraction

What time period is represented by the PR interval?

The time from the beginning of atrial contraction to the beginning of ventricular contraction

Which complex reflects the completion of cardiac depolarization?

QRS complex

Why is the QRS complex recorded as a more significant electrical activity than the P wave?

Because it reflects the contraction of the ventricles which involves more muscle mass.

What time period does the ST segment reflect?

The time between the end of ventricular contraction and the beginning of ventricular recovery

Which specific wave represents ventricular recovery?

T wave

What duration is measured by the QT interval?

The time between the beginning of the QRS complex through the T wave

On ECG paper, what time duration corresponds to a distance of $1\,mm$?

$$0.04\,sec$$

On ECG paper, what time duration corresponds to a distance of $3\,mm$?

$$0.12\,sec$$

On ECG paper, what time duration corresponds to a distance of $4\,mm$?

$$0.16\,sec$$

On ECG paper, what time duration corresponds to a distance of $5\,mm$ (one large square)?

$$0.20\,sec$$

What voltage is represented by a vertical height of $10\,mm$ on ECG paper?

$$1\,mV$$

What vertical height represents $0.5\,mV$ or $5\,mm$ on ECG paper?

$$5\,mm$$

What total horizontal distance represents $1\,sec$ on an ECG strip?

$$25\,mm$$

How many electrodes (sensors) are used to record a standard 12-lead ECG?

Ten

Where are the ten sensors distributed on the patient's body?

Two on the arms, two on the legs, and six on the chest.

What is the purpose of placing electrodes at specific locations?

To record the heart's electrical activity from different angles and planes.

Which component of the machine carries cardiac electrical impulses and magnifies them?

The leads carry the impulses into an amplifier.

In what physical position is a patient usually placed for a standard 12-lead ECG?

Supine position

List the three bipolar limb leads.

Leads I, II, and III

List the three augmented voltage leads.

aVR, aVL, and aVF

List the six chest or precordial leads.

V1 through V6

In which anatomical plane do all the limb leads lie?

Frontal plane

In which anatomical plane do the chest leads circle the heart?

Transverse plane

Where is the RA electrode placed?

On the right arm, avoiding thick muscle.

Where is the LA electrode placed?

In the same location as the RA, but on the left arm.

Where is the RL electrode placed?

On the right leg, lateral calf muscle.

Where is the LL electrode placed?

In the same location as the RL, but on the left leg.

Where is lead V1 positioned?

In the fourth intercostal space just to the right of the sternum.

Where is lead V2 positioned?

In the fourth intercostal space just to the left of the sternum.

Where is lead V3 positioned?

Between leads V2 and V4.

Where is lead V4 positioned?

In the fifth intercostal space in the mid-clavicular line.

Where is lead V5 positioned?

Horizontally even with V4, in the left anterior axillary line.

Where is lead V6 positioned?

Horizontally even with V4 and V5 in the midaxillary line.

What is the term for leads that look at the heart from the front around to the left side and are unipolar?

Precordial leads

According to international agreement, how much should the stylus deflect when the standardization button is depressed?

$$10\,mm$$

What are the dimensions of a correctly recorded standardization mark?

$2\,mm$ wide and rectangular

Why is international standardization of the ECG machine necessary?

So that an ECG can be interpreted in the same way anywhere in the world.

What is the usual recording speed for a standard ECG?

$$25\,mm/sec$$

Why might a technician adjust the sensitivity standards on an ECG machine?

To ensure the QRS complex fits properly onto the ECG paper.

Which patient demographic information must be labeled on the ECG?

Full name, gender, and age.

What clinical information regarding the timing and treatment must be labeled on an ECG?

Date and time of ECG, and a list of all medications and/or supplements.

Which precordial leads provide a view in the sagittal plane?

V1-V6

Which precordial leads are positioned over the left ventricle?

V5 and V6

What type of waves are typically seen in leads V5 and V6?

Tall R waves

Which precordial leads are positioned over the right ventricle (RV)?

V1-V3

What type of waves are the rule for leads V1-V3?

Deep S waves

What mnemonic is used to remember the placement of limb leads?

RIDE OUR GREEN BIKE

What is the anatomical term for the notch at the top of the sternum?

Manubrial notch

What is the Slight horizontal ridge or elevation on the sternum called?

Angle of Louis (sternal angle)

What two parts of the sternum join at the Angle of Louis?

The manubrium and the body of the sternum.

Which rib articulates with the sternum at the Angle of Louis?

The second rib

Where is the second intercostal space located?

Immediately below the second rib.

From which space are the third and fourth intercostal spaces located during lead placement?

The second intercostal space

Based on the Angle of Louis, where is lead V1 positioned?

In the fourth intercostal space just to the right of the sternum.

What is the process for placing V2 after V1 is located?

Find the corresponding intercostal space on the left side of the sternum.

Which electrode is skipped temporarily during the placement sequence of V1-V4?

V3

In which anatomical line is V4 placed at the 5th intercostal space?

Left midclavicular (left sagittal) line

Where is electrode V3 placed once V2 and V4 are in position?

Directly between V2 and V4.

At what level is V5 placed relative to V4?

At the same level as V4, at the anterior axillary line.

Which anatomical line is used to position lead V6?

Midaxillary line

What action usually needs to be taken with the patient's arm to place V6?

The arm usually needs to be moved to access the midaxillary spot.

According to the mnemonic, which limb corresponds to 'RIDE'?

Right upper limb (Right wrist/shoulder)

According to the mnemonic, which limb corresponds to 'OUR'?

Left upper limb (Left wrist/shoulder)

According to the mnemonic, which limb corresponds to 'GREEN'?

Left lower limb (Left ankle)

According to the mnemonic, which limb corresponds to 'BIKE'?

Right lower limb (Right ankle)

How many sensitivity standards can most ECG machines select from?

Three

What should the operator do if the ECG signals are noisy or flat after starting monitoring?

Check the leads again.

What electrical structure carries signals to the left atrium?

Bachmann's bundle

What are the final branch-like fibers of the electrical conduction system in the ventricles?

Purkinje fibers