Chapter 10 Posttest

Question 1

1. The middle layer of the heart wall that contains the atrial and ventricular muscle fibers necessary for contraction is the:
   A. Epicardium
   B. Pericardium
   C. Myocardium
   D. Endocardium

Answer 1

C

The thick, muscular middle layer of the heart wall that contains the atrial and ventricular muscle fibers necessary for contraction in the myocardium

Question 2

2. The _______ supplies the right atrium and right ventricle with blood
   A. Circumflex (Cx) artery
   B. Right coronary artery (RCA)
   C. Left main coronary artery
   D. Left anterior descending (LAD) artery

Answer 2

B

A branch of the right coronary artery supplies the right atrium and right ventricle with blood

Question 3

3. The contribution of blood that is added to the ventricles and results from atrial contraction is called
   A. Afterload
   B. Atrial kick
   C. Cardiac output
   D. Peripheral resistance

Answer 3

B

The flow of blood from the superior and inferior vena cava into the atria is normally continuous. About 70% of this blood flows directly through the atria and into the ventricles before the atria contract; this is called passive filling. When the atria contract add additional 10% to 30% of the returning blood is added to filling of the ventricles. This additional contribution of blood resulting from atrial contraction is called atrial kick. Afterload is the pressure or resistance against which the ventricles must pump to reject blood. Cardiac output is the amount of blood pumped into the aorta each minute by the heart; it is defined as the stroke multiplied by the heart rate. Peripheral resistance is the resistance to the flow of blood, determined by blood vessel, diameter, and tone of the vascular musculature.

Question 4

4. The right atrium receives deoxygenated blood from which of the following vessels?
   A. Aorta
   B. Coronary sinus
   C. Inferior vena cava
   D. Superior vena cava

Answer 4

B, C, D

The right atrium receives deoxygenated blood from the superior vena cava (which carries blood from the head and upper extremities), the inferior vena cava (which carries blood from the lower body), and the coronary sinus (which receives blood from the intracranial circulation).

Question 5

5. Which of the following are semilunar valves?
   A. Aortic
   B. Mitral
   C. Pulmonic
   D. Tricuspid

Answer 5

A, C

Pulmonic and aortic valves are semi lunar valves. Semi lunar valves prevent backflow of blood from the aorta and pulmonary arteries into the ventricles. The tricuspid and mitral valves are AV valves, separate the atria from the ventricles

Question 6

6. Stimulation of parasympathetic nerve fibers typically results in which of the following actions?
   A, constriction of coronary blood vessels
   B. Increased strength of cardiac muscle contractions
   C. Increased rate of discharge of Sinoatrial (SA) node
   D. Slowed conduction through the atrioventricular (AV) node

Answer 6

D

Parasympathetic (inhibitory) nerve, fiber supply, the SA node, atrial muscle, and the AV bundle of the heart by the vagus nerves. Parasympathetic stimulation has the following actions:
Slows the rate of discharge of the SA node
Slows conduction through the AV node
Decreases the strength of atrial contraction
Can cause a small decrease in the force of ventricular contraction

Question 7

7. Which of the following are primary branches of the left main coronary artery?
   A. Cx branch
   B. LAD branch
   C. Marginal branch
   D. Posterior descending branch

Answer 7

A, B

Left main coronary artery supplies, oxygenated blood to its two primary branches; the LAD, which is also called the anterior intraventricular artery, and the circumflex artery

Question 8

8. ________ cells are specialized cells of the electrical conduction system responsible for the spontaneous generation and conduction of electricle impulses,
   A. Working
   B. Contractile
   C. Pacemaker
   D. Mechanical

Answer 8

C

Cardiac cells have either a mechanical (contractile) or an electrical (pacemaker) function. Pacemaker cells are specialized cells of the electrical conduction system. Pacemaker cells also may be referred to as conducting cells or automatic cells. They are responsible for the spontaneous generation and conduction of electrical impulses.

Question 9

9. The absolute refractory period:
   A. Begins with the onset of the P wave and terminates with the end of the QRS complex
   B. Begins with the onset of the QRS complex and terminates at approximately the apex of the T wave
   C. Begins with the onset of the QRS complex and terminates with the end of the T wave
   D. Begins with the onset of the P wave and terminates with the beginning of the QRS complex

Answer 9

B

During the absolute refractory period, the cell with no response to further stimulation within itself. This means the mild cardio working cells contract, and the cells of the electrical conduction system cannot conduct an electrical impulse, no matter how strong the internal electrical stimulus. On the ECG, the absolute refractory period begins with the onset of the QRS complex and terminates at approximately the apex of the T wave.

Question 10

10. ST segment is measured form the:
    A,. End of the QRS to the end of the T wave
    B. Beginning of the QRS complex to end of the T wave
    C. End of the QRS complex to beginning of the T wave
    D. Beginning of the QRS complex to the beginning of the T wave

Answer 10

C

The portion of the ECG tracing between the QRS complex and the T wave in the ST segment. The term ST segment is used, regardless of whether the final wave of the QRS complex is an R or an S wave the segment represents the early part of repolarization of the right and left ventricles. The normal ST segment begins at the isoelectric line, extends from the end of the S wave, and curves gradually upward to the beginning of the T wave

Question 11

11. Which of the following states is true regarding the QT interval?
    A. The QT interval represents atrial depolarization, followed immediately by atrial systole
    B. The QT interval corresponds to atrial depolarization and impulse delay in the AV node
    C. The QT interval represents the ventricular systole.
    D. The QT interval represents the time from the initial depolarization of the ventricles to the end of the ventricular repolarization

Answer 11

D

The QT interval, measured from the beginning of the QRS complex to the end of the T wave, represents the time from initial polarization of the ventricles to the end of ventricular re-polarization

Question 12

12. Where is the positive electrode placed in lead III?
    A. Left arm
    B. Right arm
    C. Left leg/foot
    D. Right leg/foot

Answer 12

C

Lead III records the difference in electrical potential between the left leg (+) and the left arm (-) electrodes. In the lead III, deposit electrode is placed on the left leg, and the negative electrode is placed on the left arm

Question 13

13. A junctional escape rhythm occurs because of
    A. Severe chronic obstructive pulmonary disease
    B. Multiple irritable sites firing within the AV junction.
    C. Slowing of the rate of the heart primary peacemaker.
    D. Intrathoracic pressure changes associated with the respiratory cycle

Answer 13

C

Junctional escape beats and rhythms occur when the SA node fails to paste the heart or AV conduction fails

Question 14

14. How do you determine whether the atrial rhythm on an electrocardiogram tracing is regular or irregular?
    A. Compare QT intervals.
    B. Compare PR intervals.
    C. Compare P to P intervals
    D. Compare R to R intervals

Answer 14

C

To evaluate the rhythmicity of the atrial rhythm, the interval between two consecutive P waves is measured and compared to succeeding P to P intervals

Question 15

15. Which of the following ECG leads used to distinct electrodes, one of which is positive and the other negative?
    A. Lead I
    B. Lead II
    C. Lead V1
    D. Lead V6
    E. Lead aVF

Answer 15

A, B

A bipolar lead is an ECG lead that has a positive and negative electrode. Each lead records the difference in electrical potential (voltage) between two selected electrodes. Although ECG leads are technically bipolar, leads I, and II use two different electrodes, one of which is connected to the positive input of the ECG machine and the other to the negative input

Question 16

16. Leads II, III, and aVF view the hearts ______ surface?
    A. Lateral
    B. Anterior
    C. Inferior
    D. Inferobasal

Answer 16

C

Leads II, III, and aVF view the hearts inferior surface

Question 17

17. An ECG rhythm strip shows a ventricular rate of 46, a regular rhythm, a PR interval of 0.14 seconds, a QRS of 0.06 seconds, and one positive P wave before each QRS. This rhythm is.
    A. Sinus arrest.
    B. Sinus rhythm.
    C. SA block.
    D. Sinus bradycardia.

Answer 17

D

The rate of a sinus bradycardia is less than 60 bpm . R to R and P to P intervals are regular, P waves are positive in lead II, and one precedes each QRS complex. The PR interval is within normal limits and the QRS duration is 0.11 seconds or less unless is abnormally conducted

Question 18

18. In sinus arrhythmia, a gradual decreasing of the heart rate is usually associated with
    A. Expiration.
    B. Inspiration.
    C. Excessive caffeine intake.
    D. Early signs of heart failure.

Answer 18

A

In sinus arrhythmia , the heart rate increases gradually during inspiration (R to R intervals shorten) and decrease with expiration (R to R intervals lengthen).

Question 19

19. SA block is a disorder of impulse _______ and sinus arrest is a disorder of impulse _________
    A. Formation, conduction
    B. Conduction, formation

Answer 19

B

In SA block, which is also called sinus acid block, the peacemaker cells within the SA note initiate an impulse, but it is blocked as it exits the SA node; thus, SA block is a disorder of impulse conduction. Sinus arrest, which is also called sinus or SA arrest, is a disorder of impulse formation. In sinus arrest, the pacemaker cells of the SA node to initiate an electrical impulse for one or more beats resulting in absent PQRST complexes on the ECG

Question 20

20. Signs and symptoms experience during a tacky dysrhythmia are usually primarily related to
    A. Atrial irritability.
    B. Vasoconstriction
    C. Slowed conduction through the AV node
    D. Decrease ventricular filling time and stroke volume

Answer 20

D

The heart demand for oxygen increases as the heart rate increases. As the heart rate increases, there is less time for the ventricles to fill and less blood for the ventricles to pump out with each contraction, which can lead to decreased cardiac output. Because the coronary arteries fill when the ventricles are at rest, rapid heart rates decrease the time available for coronary artery filling. This decreases the blood supply. Chest discomfort can result the supplies of blood and oxygen to the heart are inadequate

Question 21

21. Which of the following are ectopic (latent) pacemakers?
    A. The SA node
    B. The ventricles.
    C. The AV junction
    D. The bundle branch.
    E. The right bundle branch.

Answer 21

B, C

The term ectopic, which means out of place, and latent are used to describe an impulse that originates from a source other than the SA node. Pacemaker sites include the cells of the AV junction and Purkinje fibers, although their intrinsic rates are slower than that of the SA node

Question 22

22. A wandering atrial pacemaker rhythm with a ventricular rate of 60 to 100 bpm may also be referred to as.
    A. Atrial flutter.
    B. Atrial fibrillation (AFib)
    C. Multi formed atrial rhythm.
    D. Multifocal atrial tachycardia.

Answer 22

C

Multi formed atrial rhythm is an updated term for the rhythm, formally known as wandering atrial pacemaker. With this rhythm, the shape and direction of the P waves vary, sometimes from beat to beat. The difference in the look of the P waves is a result of the gradual shifting of the dominant pacemaker between the SA node, the atria, and the AV junction. At pacemaker is associated with normal or slow rate and irregular P to P, R to R, and PR intervals because of the different sites of impulse formation

Question 23

23. The most common type of supraventricular tachycardia (SVT) is:
    A. Atrial flutter.
    B. Atrial tachycardia.
    C. AV re-entrant tachycardia (AVRT)
    D. AV nodal reentrant tachycardia (AVNRT)

Answer 23

D

AVNRT is the most common type of SVT

Question 24

24. Which of the following is true with regard to treatment of a symptomatic patient with AFib?
    A. With rate control, the patient remains in AFib, but the ventricular rate is reduced (controlled) to decrease acute symptoms
    B. With rate control, measures are taken (either pharmacological or electrical) to reestablish sinus rhythm

Answer 24

A

Two primary treatment strategies used to control symptoms associated with atrial fibrillation, rate control, and rhythm control. With rate control the patient remains in AFib, but the ventricular rate is controlled to decrease acute symptoms reduce signs of ischemia and reduce or prevent signs of heart failure from developing. With rhythm control sinus rhythm is reestablished

Question 25

25. In the onset or end of paroxysmal atrial tachycardia, or paracetamol, supraventricular tachycardia (PSVT) is not observed on the ECG, the dysrhythmia is called A. SVT. B. Sinus tachycardia. C. Junctional tachycardia. D. Multifocal atrial tachycardia.

Answer 25

A The term paroxysmal is used to describe a rhythm that starts or end suddenly. Atrio tachycardia that starts her and suddenly is called paroxysmal supraventricular tachycardia (PSVT), once called paroxysmal atrial tachycardia (PAT). PSVT may last for minutes, hours, or days. If the onset or end of PSVT is not observed on the ECG dysrhythmia is simply called SVT.

Question 26

26. Which of the following is the most common sustained dysrhythmia in adults? A. AFib B. Sinus bradycardia. C. Junctional rhythm. D. Ventricular tachycardia (VT)

Answer 26

A AFib is the most common sustain dysrhythmia in adults and it occurs because of altered alternativity in one or several rapidly firing sites in the atria or reentry involving one or more circuits in the atria

Question 27

27. Which of the following statements are true regarding premature atrial complexes (PACs) and premature junctional complexes (PJCs) when viewed in leads II, III, aVF? A. a PJC has a wide QRS complex B. PAC has a QRS complex. C. A P wave may or may not be present with a PJC. D. A P wave may or may not be present with a PAC E. A PAC has a positive P wave before the QRS complex F. PJC has a positive P wave QRS complex

Answer 27

B, C, E You can usually tell the difference between a PAC and a PJC by the P wave. A PAC typically has a positive P wave before the QRS complex in leads II, III, and aVF. A P wave may or may not be present with a PJC. If a P wave is present, it is inverted (retrograde) and may precede or follow the QRS. The QRS of the PC or PJC is similar in shape to those of the underlying rhythm (usually narrow) unless the early is abnormally conducted

Question 28

28. Which of the following are characteristics of wolf Parkinson’s white pattern? A. Delta waves B. Flutter waves C. Long PR interval D. Short PR interval E. Wide QRS complex F. Narrow QRS complex

Answer 28

A, D, E Care ECG findings with a Wolff-Parkinson-White pattern include a short PR interval, Delta wave, and wide QRS complex. a Delta wave is an initial slurred deflection at the beginning of the QRS complex that results from the initial activation of the QRS by conduction over the accessory pathway

Question 29

29. Which of the following ECG characteristics distinguishes atrial flutter from other atrial dysrhythmias? A. The presence of fibrillatory waves B. The presence of Delta waves before the QRS. C. Clearly identifiable P waves of varying size and amplitude. D. The “saw-tooth” or “picket fence” appearance of waveforms before the QRS

Answer 29

D In atrial flutter , atrial wave forms are produced that resembled the teeth of a saw or a picket fence; these are called flutter waves, which are best observed in leads II, III, aVF and V1

Question 30

30. When a junctional rhythm is viewed in lead II, where is the location of the P wave on the ECG if atrial depolarization and ventricular depolarization occurs simultaneously? A. Before the QRS complex B. Within the QRS complex. C. After the QRS complex.

Answer 30

B Is the AV junction pieces the heart the electrical impulse must travel in backward (retrograde) directions to the atria. If the atria depolarized before the ventricles, and inverted P will be seen before the QRS complex and the PR interval will usually measure 0.12 seconds or less. Interval is shorter than usual because an impulse that begins, and the junction does not have to travel as far simulate the ventricles. The atria ventricles polarize at the same time, a P we will not be visible because it will be hidden in the QRS complex. When the atria are depolarize after the ventricles, the P wave typically distort the end of the QRS complex and inverted P wave will appear after the QRS

Question 31

31. The usual rate of nonparoxysmal junctional tachycardia is A. 50 to 80bpm B. 80 to 120bpm C. 101 to 140bpm D. 150 to 300bpm

Answer 31

C Nonproxysmal (gradual onset) junctional tachycardia usually starts as an accelerated junctional rhythm, but the heart rate gradually increases to more than 100 bpm. Do usual ventricular rate for nonparoxysmal junctional tachycardia is 101 to 140 bpm. Paroxysmal junctional tachycardia, which is also known as focal or automatic, junctional tachycardia is an uncommon dysrhythmia that starts suddenly and that is often precipitated by a PJC. The ventricular rate for paroxysmal junction tachycardia is generally faster at a rate of 140 bpm or more.

Question 32

32. Junctional (or ventricular) complexes may appear early (before the next expected sinus beat) or late (after the next expected sinus beat). If the complex is early it is called a _________. If the complex is late it is called _________. A. Escape beat; premature complex B. Premature complex; escape beat

Answer 32

B Junctional (or ventricular) complexes may appear early (before the next expected sinus beat) or late (after the next expected sinus beat). If the complex is early, it is called a premature junctional (or ventricular) complex. The complex asleep it is called a junctional (or ventricular) escape beat. To determine if a complex is early or late you need to see at least two sinus beats in a row to establish the regularity of the underlying rhythm.

Question 33

33. Depending on the severity of the patients signs and symptoms, management of slow rhythms may require therapeutic interventions including A. Defibrillation B. Vagal maneuvers C. Administer atropine D. Administer adenosine E. Synchronized cardioversion

Answer 33

C The term symptomatic bradycardia is used to describe a patient who experiences signs and symptoms of hemodynamic compromise related to a slow heart rate. Treatment of a symptomatic bradycardia should include assessment of the patient’s oxygen saturation level and determining if signs of increased breathing effort are present. Supplemental oxygen if oxygen nation is inadequate and assist breathing ventilation is inadequate. Establish intravenous access and obtain a 12 lead ECG. Atropine, administered intravenously, is the drug of choice for symptomatic bradycardia. Reassess the patient response and continue monitoring the patient.

Question 34

34. Which statements are correct regarding junctional dysrhythmias? A. The QRS complex of a junctional rhythm is usually narrow B. A junctional rhythm is a potentially life threatening dysrhythmia C. The ventricular rhythm associated with a junctional rhythm is usually very regular D. A compensatory (incomplete) pause often follows a premature junction complex (PJC)

Answer 34

A, C Junctional skate beats and rhythms occur when the SA fails to paste, the AV junction fails. A junction rhythm starts from above the ventricles. The QRS complex is usually narrow and its rhythm is very regular. A noncompensatory (incomplete) often follow a PJC. The past represents the delay during which the SA node resets its rhythm for the next beat

Question 35

35. The term for three or more premature ventricular complexes (PVCs) occurring in a row at a rate of more than 100/min is A. A run of VT B. Ventricular trigeminy C. Ventricular fibrillation (VF) D. A run of ventricular escape beats

Answer 35

A Three or more sequential PVCs are termed a run or ab burst and three or more PVCs that occur in a row at a rate of more than 100 bpm or considered a run or VT

Question 36

36. PVCs that look alike in the same lead and begin from the same anatomic site (focus) are called _______ PVCs A. Uniform B. Isolated C. Multiform D. Interpolated

Answer 36

A PVCs that look alike in the same lead and begin from the same and atomic site (focus) uniform PVCs

Question 37

37. Which of the following dysrhythmias has QRS complexes that vary in shape and amplitude from beat to beat and appear to twist from upright to negative or negative to upright and back, resembling a spindle? A. AFib B. Monomorphic VT C. Idioventricular rhythm (IVR) D. Polymorphic ventricular tachycardia (PMVT)

Answer 37

D PMVT is characterized by QRS complexes that vary in shape and amplitude from beat to beat and appear to twist from upright to negative negative or negative to upright and back resembling a spindle. The ventricular rate is 150 to 300 bpm and typically 200 to 250bpm

Question 38

38. When a delay or interruption in impulse conduction from the atria to the ventricles occur as a result of a transient or permanent anotomic or functional impairment, the resulting dysrhythmia is called a A. SA block B. AV block C. Sinus arrest D. Bundle branch block (BBB)

Answer 38

B When a delay or interruption in impulse conduction from the atria to the ventricles occur as a result of a transient or permanent and atomic or functional impairment, the resulting dysrhythmia is called an AV block. A BBB is a disruption and impulse conduction from the bundle of his through either the right or left bundle branch to the purkinje fibers. With SA block, which is also called sinus exit block the pacemaker cells within the SA node initiate an impulse, but it is blocked as exits the SA node. Sinus arrest, the pacemaker cells of the SA node to initiate an electrical impulse for one or more beats resulting in absent PQRST complexes on the ECG

Question 39

39. Whenever the criteria for BBB have been met and lead V1 displays an rSR’ pattern, you should suspect a A. Left bundle branch block (LBBB) B. Right bundle branch block (RBBB)

Answer 39

B The rSR’ pattern is characteristic of RBBB and is sometimes referred to as an “M” or “rabbit ear” pattern

Question 40

40. The PR interval of a first degree AV block A. Is constant and less than 0.12 sec in duration B. Is constant and more than 0.20 sec in duration C. Is generally progressive until a P wave appears without a QRS complex D. Gradually decreases in duration until a P wave appears without a QRS complex

Answer 40

B A first degree AV block is present when there is a 1:1 relationship between P waves and QRS complexes and the PR interval is constant and more than 0.20 seconds duration (prolonged)

Question 41

41. Which of the following is an example of a complete AV block? A. First degree AV block B. Second degree AV block type I C. Second degree AV block type II D. Third degree AV block

Answer 41

D Second degree AV blocks are types of incomplete blocks because at least some of the impulse from the SA note are conducted to the ventricles. With third degree AV block, there is a complete block and conduction of impulses between the atria and the ventricles

Question 42

42. Identify the correct statements regrading 2:1 AV block A. The PR interval is constant B. The atrial rhythm is irregular C. The ventricular rate is twice the atrial rate D. Every other P wave is not followed by a QRS E. The level of the block is located within the SA node

Answer 42

A, D Second degree 2:1 AV block is characterized by P waves that are normal in size and shape but every other P wave is not followed by a QRS. The rate is twice to ventricular rate. Because there are no two PQRST cycles in a row from which chicken compare PR intervals, 2:1 AV cannot conclusively classified as type I or type II. to determine the type of block with certainty, it is necessary to continue close ECG monitoring of the patient until the conduction ratio of P waves to QRS complexes changes to 3:2, 4:3 and so on, which would enable PR interval comparison. With second degree AV block in the form of 2:1 AV block, the left of the block can be located within the AV note or within the his-purkinje system

Question 43

43. Which lead is probably the best to use when differentiating between RBBB and LBBB? A. II B. V1 C. V4 D. aVR

Answer 43

B Once the presence of BBB is suspected, an examination of V1 can reveal whether the block affects the right or left bundle branch

Question 44

44. The term capture, as it pertains to pacing, refers to A. A vertical line on the ECG that indicates the pacemaker has discharged B. The extent to which an artificial pacemaker recognizes intrinsic cardiac electrical activity C. A pacemaker response in which the output pulse is suppressed when an intrinsic event is sensed D. The successful conduction of an artificial pacemakers impulse through the myocardium, resulting in depolarization

Answer 44

D Capture refers to the successful conduction of an artificial pacemakers impulse through the myocardium, resulting in depolarization . A pacemaker spike is a vertical line on the ECG that indicates the pacemaker has discharged. Sensitivity is the extent to which an artificial pacemaker recognizes intrinsic cardiac electrical activity. Inhibition is a pacemaker response in which the output pulse is suppressed when an intrinsic event is sensed

Question 45

45. The 12 lead ECG only provides a ______ second view of each lead A. 1 B. 2.5 C. 4.5 D. 6

Answer 45

B The 12 lead ECG provides a 2.5 second view of each lead because it is assumed that 2.5 seconds is long enough to capture at least one representative complex. However, a 2.5 second view is not long enough to properly assess rate and rhythm so at least one continuous rhythm is usually included at the bottom of the tracing

Question 46

46. Although a right ventricular infarction (RVI) may occur by itself, it is more commonly associated with a ________ wall myocardial infarction (MI) A. Septal B. Lateral C. Inferior D. Anterior

Answer 46

C Although an RVI may occur by itself, it is more commonly associated with an inferior MI and it should be suspected when ECG changes suggesting an inferior infarction are seen

Question 47

47. Poor R wave progression is a phrase used to describe ?R waves that decrease in size from V1 to V4. This is often seen in an _____ infarction A. Inferobasal B. Anteroseptal C. Anterolateral D. Inferoposterior

Answer 47

B Poor R wave progression is ah phrase used to describe R waves that decrease in size from V1 to V4. This is often seen in an Anteroseptal infarction, but maybe normal variant and young person particularly in young women. Other causes of poor R progression include LBBB, hypertrophy and severe chronic obstruction pulmonary disease (particularly emphysema)

Question 48

48. A rapid, wide QRS rhythm associated with pulselessness, shock, or heart failure should be presumed to be A. VF B. VT C. AFib D. AVRT

Answer 48

B A rapid white QRS rhythm associated with pulse Ness , shock, or heart failure should be presumed to be VT.

Question 49

49. Which of the following characteristics of IVR? A. Ventricular rate 20 to 40bpm B. Rapid, chaotic rhythm with no pattern or regularity C. P waves may occur before, during, or after the QRS D. QRS complexes measure 0.12 sec or greater; atrial rate not discernible

Answer 49

A, D IVR, which is also called ventricular escape rhythm exists when three or more ventricular escape beats occur in a row at a rate of 20 to 40 bpm (the intrinsic firing rate of the purkinje fibers). QRS complexes scene in IVR because the impulse says begin in the ventricles bypassing the normal conduction pathway

Question 50

50. The first letter of a pacemaker identification code represents A. The chambers paced B. The chamber sensed C. The mode response D. Programmable functions

Answer 50

A The first letter of a pacemaker identification code identifies a heart chamber (or chambers) paced (stimulated). A pacemaker used to paste only a single chamber is represented by either A (atrial) or V (ventricular). A pacemaker capable of pacing in both chambers is represented by D (dual)