HPR1050241 Basic EKG Interpretation

Question 1

Epicardium

Answer 1

The outermost layer of the heart wall, forming part of the pericardium and providing a protective surface

Question 2

Endocardium

Answer 2

The thin, smooth, innermost layer that lines the heart chambers and covers the valves

Question 3

Myocardium

Answer 3

The thick, muscular middle layer responsible for the heart’s pumping action

Question 4

Pericardium

Answer 4

The double-walled sac that surrounds and protects the heart

Question 5

Mitral Valve

Answer 5

The valve between the left atrium and left ventricle that allows oxygenated blood to flow into the left ventricle

Question 6

Bicuspid Valve

Answer 6

Another name for the mitral valve, located between the left atrium and left ventricle

Question 7

Tricuspid Valve

Answer 7

The valve between the right atrium and right ventricle that allows deoxygenated blood to flow into the right ventricle

Question 8

Pulmonary Valve

Answer 8

The valve between the right ventricle and the pulmonary artery that controls blood flow into the lungs

Question 9

Ventricular Depolarization

Answer 9

The electrical activation of the ventricles that produces the QRS complex

Question 10

Atrial Repolarization

Answer 10

The electrical recovery of the atria, hidden within the QRS complex

Question 11

Atrial Depolarization

Answer 11

The electrical activation of the atria that produces the P‑wave

Question 12

Ventricular Repolarization

Answer 12

The electrical recovery of the ventricles that produces the T‑wave

Question 13

P‑wave

Answer 13

The ECG waveform representing atrial depolarization

Question 14

T‑wave

Answer 14

The ECG waveform representing ventricular repolarization

Question 15

QRS Complex

Answer 15

The ECG waveform representing ventricular depolarization

Question 16

PR interval

Answer 16

The time from the start of atrial depolarization to the start of ventricular depolarization, representing conduction through the atria, AV node, and His Purkinje system

Question 17

Sinoatrial (SA) node

Answer 17

The heart’s natural pacemaker that initiates the electrical impulse causing atrial depolarization

Question 18

Internodal pathways

Answer 18

Specialized conduction fibers that carry the impulse from the SA node through the atria to the AV node

Question 19

Atrioventricular (AV) node

Answer 19

The conduction gateway that delays the impulse to allow the atria to empty before sending it to the ventricles

Question 20

Bundle branches (Left and Right)

Answer 20

Pathways that carry the electrical impulse down the interventricular septum toward each ventricle

Question 21

Purkinje fibers

Answer 21

Fine conduction fibers that rapidly distribute the impulse through the ventricles to trigger coordinated contraction

Question 22

Polarization

Answer 22

The resting state of a cardiac cell when the inside is negatively charged and no electrical activity is occurring

Question 23

Depolarization

Answer 23

The activation of a cardiac cell when sodium enters and the cell becomes more positively charged

Question 24

Repolarization

Answer 24

The recovery phase when the cell returns to its resting negative charge after depolarization

Question 25

Na+

Answer 25

Sodium ion that moves into the cell during depolarization to create electrical activation

Question 26

K+

Answer 26

Potassium ion that moves out of the cell during repolarization to help restore the resting state

Question 27

Intrinsic rate

Answer 27

The natural firing rate of a cardiac pacemaker cell when it is not influenced by any external stimulation or autonomic input

Question 28

Sinoatrial (SA) node (intrinsic rates)

Answer 28

The primary pacemaker of the heart with an intrinsic rate of 100 to 120 beats per minute

Question 29

Atrioventricular (AV) node (intrinsic rates)

Answer 29

The backup pacemaker with an intrinsic rate of 40 to 60 beats per minute

Question 30

Purkinje fibers (intrinsic rates)

Answer 30

The ventricular pacemaker cells with an intrinsic rate of 20 to 40 beats per minute

Question 31

Sinus Rhythms

Answer 31

Normal rhythms that originate from the SA node with consistent P waves and regular conduction

Question 32

Segments and Intervals

Answer 32

Measured portions of the ECG that show timing of depolarization and repolarization within the cardiac cycle

Question 33

Junctional Rhythms

Answer 33

Rhythms that originate in the AV junction with absent or inverted P waves and a rate of 40 to 60 beats per minute

Question 34

Idioventricular Rhythms

Answer 34

Slow ventricular rhythms that originate in the ventricles with wide QRS complexes and a rate of 20 to 40 beats per minute

Question 35

Atrial Flutter

Answer 35

Atrial rhythm with rapid organized atrial activity producing sawtooth flutter waves

Question 36

Wandering Atrial Pacemaker

Answer 36

Atrial rhythm where the pacemaker site shifts between atrial locations causing varying P wave shapes

Question 37

Atrial Fibrillation

Answer 37

Chaotic atrial rhythm with no identifiable P waves and an irregularly irregular ventricular response

Question 38

Atrial Ectopy

Answer 38

Premature atrial beats that occur early and produce abnormal P wave shapes

Question 39

Junctional Ectopy

Answer 39

Premature beats that originate in the AV junction with absent or inverted P waves

Question 40

Ventricular Ectopy

Answer 40

Premature ventricular beats with wide bizarre QRS complexes that occur early

Question 41

What are the 4 characteristics or properties of cardiac cells? Give a brief definition of each and what cells they pertain to.

Answer 41

1. Automaticity The ability of a cardiac cell to generate its own electrical impulse without external stimulation Pertains to: Pacemaker cells (SA node, AV node, Purkinje fibers) 2. Excitability (Irritability) The ability of a cardiac cell to respond to an electrical stimulus Pertains to: All cardiac cells, both pacemaker and myocardial 3. Conductivity The ability of a cardiac cell to receive an impulse and pass it along to the next cell Pertains to: All cardiac cells, especially conduction pathway cells (SA node → Purkinje system) 4. Contractility The ability of myocardial cells to shorten and contract when stimulated Pertains to: Myocardial (muscle) cells, not pacemaker cells

Question 42

Three phases of the cardiac action potential: Polarization

Answer 42

Resting membrane potential, no electrical activity K+ flows into cell (this refers to maintaining the resting state)

Question 43

Three phases of the cardiac action potential: Depolarization

Answer 43

Stimulation of cardiac muscle cells Na+ flows into the cell P wave and QRS complex shown on the EKG

Question 44

Three phases of the cardiac action potential: Repolarization

Answer 44

Na+ influx stops Membrane potential returns to resting level T wave shown on the EKG