EKG Quiz 1 Chapters 1-4

Question 1

What do the pulmonary veins deliver? Blood to where?

Answer 1

Pulmonary veins are large veins that return oxygenated blood from the lungs to the left atrium. They are the ONLY veins that carry oxygenated blood.

Question 2

If a patient has chills, what type of tremor is being experienced?

Answer 2

Somatic tremor is a jittery pattern caused by patient’s tremors or by shaking wires.

Solutions: Offer a blanket or help the relax; make sure wires are not tangled or loose

Sometimes this artifact cannot be corrected such as patient with constant tremors from Parkinson’s disease.

Question 3

Define T waves

Answer 3

T wave represents ventricular repolarization. The normal T wave is broad and rounded. If there is a QRS complex, there MUST be a T wave after it. Any tissue that depolarizes must repolarize or else it will never depolarize again.

* T waves are the small bumps after a QRS complex*

Question 4

Explain the role of semilunar valves

Answer 4

Semilunar valves are 2/4 valves the heart has to prevent backflow of blood.

Semilunar valves separate a ventricle from an artery and have three half-moon shaped cusps. The two semilunar valves are:

1. pulmonic: valve located between right ventricle and pulmonary artery
2. aortic: valve located between left ventricle and aorta

Question 5

Know the phases of an action potential

Answer 5

In phase 4, cardiac cell is at rest. Electrically nothing is happening, this electrical silence is indicated by a flat line.

In phase 0 cardiac cell is stimulated as sodium rushes into the cell and potassium leaks out, resulting in a positive charge within the cell. The cell is now depolarized and the QRS complex spikes up.

Phases 1 and 2 are early repolarization. Calcium is released resulting in contraction. Phases 1 and 2 correspond with the ST segment of the EKG (ST segment is a flat line that follows the QRS and comes before the T wave). Technically phase 2 is called the plateau phase before waveform levels off.

Phase 3 is rapid repolarization after sodium and potassium return to normal places. Phase 3 corresponds with the T wave of an EKG. After repolarization, cardiac cell relaxes.

Question 6

Know the 3 types of augmented leads

Answer 6

Augmented Leads:

1. aVR: measures current traveling toward right arm; positive electrode on the right arm
2. aVL: measures current traveling toward left arm; this is a positve electrode on the left arm
3. aVF: measures current traveling through left foot/leg; this is a positve electrode on the left leg

Question 7

Know bipolar leads & their associated poles

Answer 7

Bipolar Leads are named because they require positive and negative pole:

1. Lead I: measures current traveling between right and left arms; right arm negative and left arm is positive
2. Lead II: measures current traveling between right arm and left leg; right arm is negative and left leg is positive
3. Lead III: measures current traveling between left arm and the left leg; left arm is negative and left leg is positive

*Right arm is ALWAYS NEGATIVE and left leg is ALWAYS POSITIVE. Note that left arm can be either positive eor negative depending on which lead being used*

Question 8

What is responsible for the sounds made by the beating heart?

Answer 8

Valve closure is responsible for the sounds made by the beating heart. The normal lub-dub of the heart is made not by blood flowing through the heart, but by the closing of the valves.

S1, the first heart sound, reflects closure of mitral and triscupid valves (AV valves); S2 the second heart sound reflects closure of aortic and pulmonic valves (Semilunar valves)

Between S1 and S2, the heart beats and expels its blood (called systole). Between S2 and next S1, heart rests and fills with blood (diastole)

Question 9

How do you check calibration?

Answer 9

Standardization: This checks the machine’s calibration. Throwing 1 millivolt of electricity into the EKG machine should cause the stylus (pen) to print out square wave 10mm high on the EKG paper.

Do not use a machine thats not calibrated properly

Question 10

Define relative refractory

Answer 10

Refractory means “resistant to”. There are three types:

1. absolute: cell cannot accept another impulse because it’s still dealing with the last one
2. relative: strong stimulus will result in depolarization
3. supernormal period: cardiac cell during this period is still hyper and doesn’t take much to set it off and running

Question 11

What is Einthoven’s law?

Answer 11

Einthoven’s law states that lead I + lead III = lead II

This means that height of QRS in lead I added to height off QRS in lead III will equal to the height of the QRS in lead II. Lead II should have tallest QRS. Einthoven’s law can determine if EKG is truly abnormal or if leads were inadvertently placed.