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ALU 301 > Chapter 7- Introduction to Electrocardiography and Cardiac Arrhythias > Flashcards

Chapter 7- Introduction to Electrocardiography and Cardiac Arrhythias Flashcards

1
Q

What is the most commonly used non-invasive diagnostic cardiac test worldwide?

A

EKG

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2
Q

What is the purposed of the cardiovascular system

A

to meet the O2 demands of the body and to transport waste products away from tissues for excretion.

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3
Q

What conditions must be met for the heart to function effectively?

A
  1. contraction of the muscle cells must occur at regular intervals and be synchronized
  2. Ventricular contractions must be forceful
  3. Heart valves must be competent, allowing only one-directional flow of blood
  4. the ventricles must fill adequately during diastole.
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4
Q

The heart is made up of two catergories of specialized cardiac cells- what are they?

A
  1. myocardial cells- generate the contractile force necessary to propel blood
  2. pacemaker cells- provide electrical stimulus necessary to initiate contraction of the myocardial cells in a coordinated manner and at appropriate intervals.
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5
Q

Describe the conduction system

A

composed of pacemaker cells and is responsible for initiating and transmitting the electrical impulse required to stimulate contractions of the myocardial cells.

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6
Q

What are the 4 components of the conduction system?

A
  1. Sinoatrial Node (SA node)
  2. Atrioventricular Node (AV node)
  3. The bundle of HIS
  4. The purkinje fibres.
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7
Q

define the SA node

A

located superior and posterior wall of Rt. Atrium

  • spontaneously initiates each electrical impulse and governs the physiologic HR.
  • pulse generated travels from SA through inter-nodal pathways to the AV node.
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8
Q

Define the AV node

A

located at AV junction
- impulse comes in and prior to being transmitted to the bundle of HIS its delayed to allow the valves to open, and ventricular wall to relax/atria to contract.

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9
Q

Define the Bundle of HIS

A

located in the septum and divides into Rt bundle branch and Lt bundle branch. Lt bundle branch then divides into anterior and posterior fascicles.&raquo_space; this allows for electric impulse to be rapidly transmitted

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10
Q

Define the Purkinje fibres

A

network of conducting strands that lie beneath the ventricular endocardium
- They conduct the impulse to the myocardial cells.

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11
Q

Define the voltage process across cell membranes using action potential, depolarization, contraction, repolarization.

A

ions (Na+, K+ and Ca++) move across cell membranes. When resting cells are in an electrcial-balanced state, the action potential is the voltage change that occurs across the cell membrane during the cardiac cycle as a result of electrolyte exchanges. depolarization happens when the electrical activation of myocardial cells due to the spread of an electric pulse. Contraction is the mechanical event that occurs after depolarization. Repolarzation is the action of which the cell returns to the resting state.

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12
Q

What is seen on an electrocardiogram?

A

voltage between two points on the body surface and its changes over time d/t events of the cardiac cycle.

it measures the electric current, direction and magnitude and rate of impulse.

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13
Q

Standardized technique for EKGs have been developed using specialized graphic paper and standard paper speeds and amplitudes. Define this.

A

the width of each square = interval time, large [] are 0.2 seconds and small [] are 0.04seconds. Hight of each square is voltage. Large [] is 0.5mv (or 5mm) and small [] is 0.1mv (or 1mm).

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14
Q

limb leads are formed by placing electrodes on or near the Rt and Lt arms and Lt leg. What are the two types of limb- leads?

A
  1. bipolar leads - utilize one +ve and one -ve electrode and leads 1,2,3.
  2. Unipolar leads- just one positive electrode, augmented leads, since voltage is amplified by EKG machine during recording. Leads include: AVR, AVL, and AVF.
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15
Q

What are Percordial (Chest) Leads?

A

unipolar leads - pt lie in horizontal plane perpendicular to both the chest and to the frontal plane of the limb leads.
- Leads: V1 thought V6, across the chest.

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16
Q

When reading Wave-forms and intervals of an EKG. What is the P wave?

A

represents atrial depolarization

  • usually rounded, 3 mm by 0.11 seconds (h x w)
  • upright in leads 1,2, AVF, and V4, V5, V6.
  • negative in AVR and possibly negative in V1.
  • can fall below and above baseline in leads 3, AVL, V1, V2, V3.
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17
Q

When reading Wave-forms and intervals of an EKG. What is the PR interval?

A
  • measured from P to QRS complex.
  • time required for depolarization of the atrial to the onset of depolarization of the ventricles.
  • 0.12 to 0.20 sec.
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18
Q

When reading Wave-forms and intervals of an EKG. What is the QRS complex.

A

ventricular depolarization

  • Q is initial downward deflection
  • R wave is the first upright (+ve deflection)
  • S wave is a -ve deflection (second negative deflection is Q wave is negative or first negative deflection that occurs after an R wave)
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19
Q

What is an abnormal Q characteristics?

A

duration of 0.04 seconds and depth of 25%

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20
Q

When reading Wave-forms and intervals of an EKG. How long is the QRS interval?

A

<0.10 second

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21
Q

What is an abN QRS interval characteristic?

A

duration of 0.10-.11 seconds is a Incomplete BBB.

duration >0.12 seconds is a complete BBB or intraventricular conduction abN

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22
Q

When reading Wave-forms and intervals of an EKG. What is the ST segment?

A

horizontal, isoelectric segment that represents the completion of ventricular depolarization/start of ventricular repolarization.

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23
Q

What is an abN ST segment?

A

depression of 1mm or grater = cardiac pathology

Slight displacement = possible normal variant.

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24
Q

When reading Wave-forms and intervals of an EKG. What is the T wave?

A

ventricular repolarization, same direction as QRS complex.

slightly rounded and Asymetric with smooth takeoff

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25
Q

What are abnormal T -wave characteristics?

A

minor, flat T waves
abnormal inverted (major) T waves
» Could be a cardiac etiology but can also be non-cardiac in nature.

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26
Q

When reading Wave-forms and intervals of an EKG. What is the QT interval?

A

total time required for both depolarization and repolarization fo the ventricles.

  • measured from start QRS complex to end of T wave.
  • normal = 0.35 to 0.45 seconds.
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27
Q

When reading Wave-forms and intervals of an EKG. What is the U wave?

A

small deflection following T wave.

- significance is unknown.

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28
Q

What is a normal heart rate?
What is bradycardia?
What is Tachycardia?

A

60-100 bpm
<60 bpm
>100 bpm

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29
Q

What factors can affect heart rate?

A
  1. age
  2. fitness level
  3. illness
  4. medications
  5. body temperature.
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30
Q

What are two methods for determining an approximate heart rate?

A
  1. count number of bold large squares between two QRS complexes,
  2. 6-second method: 6 seconds on EKG is 30 bold squares. count the number of QRS complexes in a 6-second trip and multiply by 10 &raquo_space; better method for determining irregular heart rates.
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31
Q

What controls the impulse rate of the heart?

A

SA node is primary pace maker at impulse rate of 60-100x/min
back-up pacemaker in AV node is rated at 45-50bmp, and back-up in the ventricles rated at 35-45bpm.

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32
Q

What is the EKG criteria for sinus rhythm ?

A
  1. HR 60-100 bpm
  2. P waves: are identical and normal looking, occur in regular rhythm, exhibit a constant PR interval of 0.12-0.20 sections
  3. P wave is followed by a QRS complex.
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33
Q

define arrhythmia

A

variation from the normal rhythm of the heart, encompassing abnormalities of rate, regularity, site of impulse origin, and sequence of activation.

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34
Q

What is atrial arrhythmia?

A

occurs as a result of an ectopic impulse generated in the atria but not by the SA node.

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35
Q

define the term Supra-ventricular?

A

above the ventricle and used to describe some atrial arrhythmias.

36
Q

What is a Premature Atrial Contraction (PAC)?

A

results from an ectopic impulse that originates in the atria outside of the SA node.

  1. impulse occurs prior to next expected sinus impulse
  2. P wave morphology is abN s/t path of impulse is off of impulse pass from SA node
  3. PR interval is inconsistent d/t distance from the site of the ectopic impulse to the AV node is different than that of the SA node to the AV node.
37
Q

What are some common causes for PACs?

A

stress
Caffeine
alcohol
- they’re usually benign.

38
Q

What are Premature Junctional contractions?

A

Much like PACs except the impulse comes from the AV nodal junction.
P wave can be inverted with short PR intervals or embedded in the QRS complex.
- benign findings

39
Q

What is a wandering atrial pacemaker?

A

condition in which pacemaker impulses originate from two or more sites in the SA node, atrial or AV junction.

  • discharged at 45-100 bpm.
  • P wave will vary depending on site, rhythm is irregular but QRS complex is normal
  • usually benign
40
Q

What is Atrial Tachycardia?

A

sudden onset of rapid rhythm originating from ectopic foci in the atria and outside of SA note.

41
Q

There are many types of Atrial Tachycardia, and they differ with regards to what 7 characteristics?

A
  1. morphology of P wave
  2. atrial rate
  3. AV conduction
  4. duration of the arrhythmia
  5. hemodynamic consequence
  6. electrophysiolgic mechanism
  7. Etiology.
42
Q

What causes Atrial tachycardias?

A 
idiopathic 
Valvular disease
CAD
pulmonary disease
medication
abnormal accessory pathways in the conduction system 
Alcohol/ Caffeine
43
Q

What are some complications that can arise from Atrial tachycardia and what is the treatment?

A

can lead to sxs of SOB, CP, dizziness and syncope. Can lead to sxs of congestive heart failure
- tx is to restore sinus rhythm.
Rx beta-blockers, anti-arrhythmics drugs, CA+ blockers, and digoxin.
ablation,

44
Q

What is the most common arrhythmia?

A

Atrial Fibrillation

  • A supraventricular arrhythmia characterized by the chaotic, rapid discharge of impulses from multiple ectopic foci in the atria.
  • Ventricular rate is slower than rapid atrial rate.
  • Can be proxysmal or chronic
45
Q

AF is irregularly irregular rhythm. What would you see on the EKG?

A
  1. irregular r-r intervals
  2. loss of P waves
  3. Fine, fibrillatory waves on baseline
  4. QRS complex that usually si normal, except when ventrical conduction is abN
  5. ST-T wave abnormalities that can be due to abnormal repolarization, rate-induced ishemia or Rx effects.
46
Q

What causes AF?

A 
age 
valvular and congential heart disease 
cardiomyopathy 
sick sinus syndrome 
hypertension
pulmoary disease
alcohol use
hyperthyroidism 
idiopathic causes.
47
Q

What are some complications asscoiated with AF?

A
  1. embolic stroke- incomplete emptying of atria causes pooling of blood = possible thrombi
  2. ischemia, infraction, and congestive heart failure d/t incompleting emptying of the atria, reduced filling of ventricles and inadequate emptying of the ventricules during systole
48
Q

How is AF treated?

A

Treat for Cause
Rx: Calcium channel blockers, beta blockers, antiarrhythmics or digoxin - help restore/maintain sinus rhythm or to control ventricular responses.
anti-platelet drugs to mitigate stroke risk.
ablation of focal triggers of AF.
pacemaker

49
Q

What is Atrial Flutter?

A

supraventricular dysrhythmia characterized by appearance of sawtooth-shaped flatter waves (250-350 bpm)
cause and tx are similar to AF.

50
Q

What is a Premature ventricular contraction (PVC)?

A

Occurs as a result of an early impulse discharging from an extopic focus in the ventricle

  • in a healthy person its usually one-off benign
  • if frequent or sequential, they can cause impaired CV function.
51
Q

What are the EKG characteristics of a PVC?

A
  1. impulse is early
  2. there is no P wave
  3. QRS complex is wide and abN d/t impulse originating from a different side and travelling different paths
  4. there is often a compensatory pause before the nromal rhythm picks back up
52
Q

How is the significance of a PVC determined?

A
  1. frequency - number of PVC’s per minute
  2. Pattern
  3. morphology : unifocal vs mutifocal
  4. presence during exercise (increase # s/t stress is suspicious for CV disease)
  5. Proximity to the previous T wave.
53
Q

What are the different types of PVC patterns?

A

bigeminty (every other beat is PVC)
trigemity (3rd beat) couplet: Two sequential PVS
triplet: 3 sequential PVC
Ventricular tachycaria: >3 PVCs in a row. if <30s its non-sustained, and converts spontaneously, if greater than 30s its called sustained.

54
Q

PVCs can be idiopathic, but what are 8 other significant causes?`

A
  1. myocardial ischemia/injury
  2. dilated or hypertrophic cardiomyopathy
  3. mitral valve prolapse
  4. hypoxia from any cause
  5. medications
  6. stimulants
  7. illicit drugs
  8. electrolute imbalances
55
Q

Are there sxs with PCS?

A 
only when theyre more frequent or complex:
palitations
CP 
SOB 
dizziness
syncope
56
Q

What is an implantable cardiac defibrillator (ICD)

A

device that senses when heart develops VT or VF and provides appropriate voltage to defibrillate the heart to convert rhythm back to normal.

57
Q

What is Sick Sinus Syndrome (SSS) ?

A

condition characterized by periods of extreme bradycardia, tachycardia sinus arrest, AV blocks and failure to escape pacemakers to function.

58
Q

Signs and symptoms associated with SSS are related to the reduced cardiac output caused by the disorder. what are they (7)?

A 
dizziness
syncope
hypotension
fatigue 
Chest pain 
SOB 
Congestive heart failure
59
Q

What is a Sinoatrial (SA) block?

A

represents impaired conduction either within the sinus node or from the SA node to the conduction pathway fibres in the atria.

  • 1 cardiac cycle followed by return of normal SA node function.
  • EKG: shows absence of the entire P-QRS-R complex.
60
Q

What is Sinus Arrest?

A

sudden failure of the SA node to initiate impulse formation.

  • associated with SSS.
  • Back up pacemaker kicks in - known as escape beats/rhythm`
61
Q

What is a First-Degree AV block?

A

characterized by a persistently prolonged PR interval >0.20s that occurs d/t partial block within the AV node.
- Usually benign

62
Q

What is Second-Degree AV block Mobitz type 1?

A

disorder of intermittent conduction between the atria and ventricles.
location of the block is in the AV node.
ECK- shows lengthen PR interval until QRS is dropped d/t atrial impulse fail.
- usually benign

63
Q

What is Second-Degree AV block Mobitz type 2?

A

intermittent and sudden loss of conduction between the atria and ventricles for one or more cardiac cycles without escape beat or rhythm.

  • block is usually below bundle of His.
  • caused by MI, drugs, or SSS.
  • EKG: possible widened QRS complex .will show intermittent and suddenly dropped QRS complex.
  • sxs: sxs similar to SSS
  • condition progresses and usually needs s pacemaker.
64
Q

What is third-degree AV block?

complete heart block, AV dissociation

A

complete absence of conduction between atria and ventricles.

  • Complete block in ventricular conduction system that prevents normal conduction of the impulse through ventricles
  • EKG: consistent P-P and R-R intervals, Atrial rate is different from Ventricular rate.
  • no relationship between P waves and QRS complexes
  • if rhythm cant be restored, then condition is tx’ed with implantation of pacemaker
65
Q

What causes a Third-Degree AV block?

A
  1. drug toxicity
  2. excessive vagal tone
  3. Acute MI
  4. Age-related degeneration of the conduction systems.
  5. congenital disorders.
66
Q

What are Axis variations that you should be aware of?

A
  1. if both leads are +Ve (upright) than the axis is normal
  2. If lead 1 is +ve and AVF is -ve, look at lead 2. If +ve or isoelectric than its normal. If -ve then axis is consistent with LAFB.
67
Q

What are some significant disorders associated with Left Anterior Fascicular Block (LAFB)?

A
  1. Hypertensive heart disease
  2. CAD
  3. aortic valve disease
  4. Degenerative fibrotic disease
  5. Emphysema.
68
Q

What are some pathologic causes of Right Axis deviation (RAD)?

A
  1. Chronic lung disease
  2. atrial or ventricular septal defect
  3. Rt. Ventricular hypertrophy
  4. Lt posterior hemiblock
69
Q

What is Bundle Branch Blocks?

A

represents defects in intraventricular conduction

  • involves blocked conduction within the ventricles
  • Slow impulse conduction through ventricles = abN depolarization characterized by wide QRS complex >0.12s.
  • no sxs, no Tx.
70
Q

Complete Right Bundle Branch Block (CRBBB) results from conduction delay within Rt. Bundle Branch. Can be idiopathic or caused by what?

A
  1. Right ventricular hypertrophy (RVH)
  2. Atrial Septal Defect (ASD)
  3. CAD
  4. Chronic Lung disease
71
Q

Left Bundle Branch Block (LBBB) can result from a conduction delay or block within Left bundle branch caused by what etilogy?

A
  1. Left ventricular hypertrophy
  2. cardiomyopathy
  3. hypertension
  4. CAD
72
Q

Fascicular blocks are disturbed conductions in the anterior or the posterior division, or fascicle, of the Lt Bundle Branch. Which is more common, and what causes this abnormality?

A

LAFB (anterior) is more common than LPFB (posterior)
LPFB is usually more sig for underlying cause being:
1. CAD
2. MI
3. CHD
4. Prior cardiac surgery

73
Q

What are the EKG characteristics for LAFB?

A
  1. QRS duration prolonged (0.08-0.11s)
  2. Lft axis deviation
  3. small Q wave and Tall R wave in Leads 1 and AVL
  4. Small R wave and deep S wave in Leads 2, 3, and AVF
    5, Poor R wave progression in precordial leads
74
Q

What is the EKG criteria for LPFB

A
  1. QRS duration prolonged (0.08-11s)
  2. Rt axis deviation (+90 to +180 degrees)
  3. Small Q wave and Tall R wave in leads 2, 3, AVF.
  4. small R wave and Deep S wave in leads 1 And AVL.
75
Q

What is Dilated or Hypertrophic chamber enlargement?

A
  1. dilated (increase in internal diameter)

2. Hypertrophy (increase in wall muscle thickness)

76
Q

What are some common causes of atrial enlargement?

A
  1. valvular stenosis or regurgitation
  2. congenital heart defects
  3. chronic pulmonary disease
77
Q

What are some EKG findings associated with atrial chamber enlargement?

A

changes in voltage (height or width of the P waves) seen in inferior leads (2, 3, and AVF) and in leads V1 and V2.

78
Q

What are some common causes of Ventricular chamber enlargement?

A
  1. stenotic or regurgitation valves
  2. pulmonary and systemic atrial hypertension
  3. cardiomyopathies.
79
Q

What are the EKG findings for Ventricular Chamber enlargement?

A

increase voltage of QRS complex
abnormal axis
ST-T wave changes associated with secondary repolarization changes.

80
Q

What can cause LVH and RVH?

A

left: hypertension, valve disease, or cardriomyopathy
Right: increase workload and pressure.

81
Q

What abnormalities occur in specific lead patterns that represent particular portions of the ventricular muscle?

A

inferior wall: Leads 2, 3, AVF
Septal wall: Leads V1, V2
Anterior wall: leads V1, V2, V3, and V4
Lateral walls: leads 1, AVL, V5, and V6.
Posterior wall- reciprocal changes in V1 and V2.

82
Q

What does Myocardial ischemia look like on an EKG?\

Temporary, reversible reduction of blood supply to heart muscle.

A

T wave changes from upright asxs to deeply inverted and symmetrical

83
Q

What does Myocarial injury look like?

reversible if blood flow to area of jeopartized myocaridum is restored before the tissue dies.

A

the normal isolectric ST segment is elevated and ischemia shows ST depression
ST changes >1mm is significant.
ST depression as horizontal or downsloapping is suspecious.&raquo_space; CAD is indicated when this occurs during exercise

84
Q

What does Myocaridal infarction look like?

irreversible death of heart muscle d/t absence of blood flow

A

Q waves in leads represent the area of damage.
abN Q wave is silent areas of infarcted heart muscle.
must be 0.04s in duration and deeper than 25% of the height of the adjacent R wave.

85
Q

What is Wolff-parkinsons-White (WPW) synfrome?

A

ventricular preexicitation in which the ventricles are depolarizing using both congenital accessory bypass tract and normal AV conduction pathways.

  • PR interval is abN short, and QRS is slurred and widended.
  • tx’ed when it develops into a worse arrythmia via ablation.
86
Q

What is Lown-Ganong-Levine Syndrome?

A

rare intranodal bypass tract syndrome accompanied by recurrent SVT.
= Short PR interval with no delta wave and normal QRS complexes.

87
Q

What is prolonged QT-syndrome?

A

results from an increased risk of ventricular tachyarrhythmias, leading to syncope, cardiac arrest, or sudden death.
- congenital disorder, and somtimes drug-induced.
tx with Rx, to suppress arrhythmia and maintain normal electrolyte balance and implantation of an implatable carioverter-defibrillator. `

ALU 301 (14 decks)

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