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Cardiovascular > SM 136 Tachyarrhythmias > Flashcards

SM 136 Tachyarrhythmias Flashcards

1
Q

What are the basic causes of Tachyarrhythmias?

A

Abnormal Automaticity, Triggered Activity, and Reentry

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2
Q

Which causes of Tachyarrhytmias arise from abnormalities in impulse formation?

A

Abnormal Automaticity and Triggered Activity = initiated by a focal source

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3
Q

Which cause of Tachyarrhytmias arise from abnormalities in impulse propagation?

A

Reentry (most common) = initiated from a circuit

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4
Q

What underlies Abnormal Automaticity in Tachyarrhytmias?

A

Changes in the pacemaker activity of non-sinus node cells, such as an increase in the slope of Phase 4 depolarization or a reduced Vt in Phase 0

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5
Q

What changes result in Abnormal Automaticity?

A

Changes in electrolyte levels

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6
Q

What underlies Triggered Activity in Tachyarrhytmias?

A

Increased Ca levels that lead to afterdepolarizations

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7
Q

What is an afterdepolarization?

A

An abnormal depolarization due to increased calcium levels stemming from gene mutations that alter Ca balance; can trigger an AP if the influx is large enough

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8
Q

During which phases of the AP and in what cells can an afterdepolarization trigger an additional AP?

A

During Phase 3 and Phase 4, when the cell is relatively refractory

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9
Q

During which phases of the AP and in what cells can an afterdepolarization NOT trigger an additional AP?

A

During Phase 1 and Phase 2, when the cell is absolutely refractory

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10
Q

What is an Early afterdepolarization?

A

EAD; occurs in Phase 3

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11
Q

What is a Delayed afterdepolarization?

A

DAD; occurs in Phase 4

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12
Q

Does Triggered Activity have a focal or circuit source of arrythmia?

A

Triggered Activity has a focal source of arrythmia

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13
Q

Does Reentry as a cause of Tachyarrhytmia have a focal or circuit source of arrhythmia?

A

Reentry develops from an extra pathway forming a circuit in the myocardium with premature atrial OR ventricular beats initiating the circuit and cycles of contraction

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14
Q

What is the necessary prerequisite for AVNRT?

A

A Fast and Slow pathway around the AV Node, which exists in 10% of people

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15
Q

How do Sinus rhythms use the Fast and Slow Pathways?

A

A normal beat can bifurcate and travel through the Fast pathway to form a normal beat; the end that travels through the Slow pathway arrives at tissue that is already depolarized and has no effect = normal PR

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16
Q

How do Premature Atrial Beats use the Fast and Slow Pathways?

A

Premature atrial beats arrive at the bifurcation around the AV Node, but find the Fast pathway is in the refractory period and therefor blocked. They travel around the Slow pathway to downstream tissue = elongated PR; they also try to ascend the Fast pathway after causing the long PR, but it is still refractory so the signal dies

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17
Q

How do AV Nodal Echo’s use the Fast and Slow Pathways?

A

Premature atrial beat arrives at the bifurcation around the AV Node, encounter a blocked Fast pathway due to repolarization. Travel down the Slow pathway to tissue downstream = elongated PR, and travel up the repolarized and unblocked Fast Pathway back to the Atria = inverted P wave after QRS; cannot progress further because the Slow Pathway is still refractory, signal dies

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18
Q

How does AVNRT use the Fast and Slow pathways?

A

Premature atrial beat arrives at the bifurcation around the AV Node, bypasses blocked Fast pathway due to repolarization and travels down Slow pathway to downstream tissue = long PR; travels back up the Fast pathway which is now repolarized and unbloked to the bifurcation, where the signal splits and travels back to the Atria = inverted P wave after QRS; progresses back down the Slow pathway which is now unblocked and forms a cycle

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19
Q

Describe the conduction and refractory period of the Fast pathway?

A

Conduction = rapid; Refractory period = long

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20
Q

Describe the conduction and refractory period of the Slow pathway?

A

Conduction = slow; Refractory period = short

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21
Q

What effect does AVNRT have on the previous sinus rhythm?

A

AVNRT abolishes the sinus rhythm by suppressing SA Node firing

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22
Q

Where do Supraventricular Tachycardias occur?

A

SVT occur above the ventricle, and do not include Sinus Tachy

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23
Q

What does AVNRT stand for?

A

Atrial Ventricular Node Reentrant Tachycardia

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24
Q

How does PSVT present?

A

Regular, narrow QRS Tachycardia

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25
Q

What are the types of PSVT?

A

AV Nodal Reentrant Tachycardia (AVNRT), Atrio-ventricular reentrant Tachycardai (AVRT), and Arial Tachycardia (AT)

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26
Q

What is the most common form of PVST?

A

Of the 3 types of PVST (AVNRT, AVRT, AT), AVNRT is the most common

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27
Q

What is the least common form of PVST?

A

Of the 3 types of PVST (AVNRT, AVRT, AT), AT is the least common

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28
Q

What symptoms are associated with the 3 types of PVST?

A

May be asymptomatic, but can involve heart racing, syncope, chest discomfort

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29
Q

What is syncope?

A

Loss of consciousness

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30
Q

What is necessary for Atrioventricular Reentrant Tachycardias to emerge?

A

Anomalous bypass tracts aka accessory pathways

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31
Q

How do Accessory Pathways form between the Atria and the Ventricles?

A

Normally, the AV valves partition the Atria and Ventricles, insulating both anatomically and electrically; when defects occur, bundles of muscle may connect the Atria and Ventricles allowing for conduction of impulses outside the normal cardiac conduction system

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32
Q

How do Accessory Pathways present on EKG?

A

Preexcitation Delta waves that slur the beginning of the QRS complex

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33
Q

Do Bypass Tracts run Top-Down, Bottom-Up, or bidirectionally between the Atria and Ventricles?

A

All of the above

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34
Q

Which direction must a Bypass Tract conduct to show up on EKG?

A

Bypass Tracts must conduct Top-Down to show up on EKG, where they show up as extra QRS complexes; in theory, a Bottom-Up tract could form an inverted P wave

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35
Q

How do Delta waves form during AVRT?

A

Electrical conduction occurs outside of the AV Node and begins to partially depolarize the ventricles during the PR interval, when the AV Node is normally delayed, forming the Delta wave at the beginning of a QRS complex

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36
Q

What component of the AVRT is the Fast Pathway?

A

The Bypass Tract is the Fast Pathway, since unlike the AV Node, it does not have a built in delay

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37
Q

What component of the AVRT is the Slow Pathway?

A

The AV Node, because it has a built in delay

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38
Q

What are the components of the AVRT?

A

The Bypass Tract (Fast) and the AV Node (Slow), as well as the intervening Atrial and Ventricular Tissue between the two pathways

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39
Q

What are the 2 types of AVRT?

A

Orthodromic and Antidromic Tachycardia

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40
Q

What is Orthodromic Tachycardia?

A

A type of AVRT where signal flows from the AV node, down the Ventricles via His-P, and back up the Accessory Pathway = narrow QRS

41
Q

What is Antidromic Tachycardia?

A

A type of AVRT where signal flow from through the Accessory Pathway, up the Ventricles via Gap Junctions and up to the AV Node = wide QRS

42
Q

What would AVRT with Wide QRS complexes indicate and why?

A

Wide QRS complexes suggest that the signal is passing through the ventricles outside of the His-P system, and points to Antidromic Tachycardia

43
Q

What would AVRT with Narrow QRS complexes indicate and why?

A

Narrow QRS complexes suggest that the signal is passing through the ventricles along the His-P system, and points to Orthodromic Tachycardia

44
Q

How is Atrial Tachycardia treated?

A

AT is treated with drugs such as Beta Blockers

45
Q

Does the Valsalva Maneuver work on AT?

A

No, because the circuit involved in AT is contained in the Atria and increased Vagal stimulation to the AV Node via the maneuver would have no effect

46
Q

How does the Valsalva Maneuver work?

A

Block an airway and try to force respiration, results in increased Vagal Tone on the AV Node that can terminate SVT

47
Q

Which SVT can be terminated by the Valsavla Maneuver?

A

AVNRT and AVRT, because they involve the AV Node and Vagal Stimulation can inhibit the AV Node

48
Q

Is Atrial Tachycardia circuit based or focal?

A

AT is focal and does not require the AV Node

49
Q

What are the mechanisms underlying AT?

A

Triggered, automatic, and micro-reentry (a small circuit that appears focal)

50
Q

When does multifocal AT arise?

A

3 or more P wave morphologies, irregular, seen in Pulmonary disease

51
Q

What is the most common arrhythmia?

A

Atrial Fibrillation

52
Q

How does Atrial Fibrillation present?

A

Disorganized atrial activity + irregularly irregular ventricular response

53
Q

What is a regularly irregular rhythm?

A

R waves that occur in varying distance with a pattern

54
Q

What is an irregularly irregular rhythm?

A

R waves that occur in varying distances without a pattern

55
Q

How does Fibrillation present?

A

Irregular and disorganized

56
Q

What atrial rate is associated with Fibrillation?

A

Rate > 350bpm

57
Q

How does Flutter present?

A

Regular and Organized

58
Q

What atrial rate is associated with Fibrillation?

A

240bpm - 350bpm

59
Q

What are the mechanisms behind Atrial Fibrillation?

A

Focal, Mother Rotor, and Multiple Wavelets

60
Q

What is the Focal mechanism of Atrial Fibrillation?

A

Rapid focal source that conducts throughout the atria in a disorganized fashion to cause AFib

61
Q

What is the Mother Rotor mechanism of Atrial Fibrillation?

A

One large functionally reentrant circuit that produces smaller wavelets which cause AFib

62
Q

What is the Multiple Wavelets mechanism of Atrial Fibrillation?

A

Many small reentrant circuits in the atria that cause AFib

63
Q

Define Ventricular Tachycardia?

A

VT has discrete QRS complexes and Rate > 100bpm

64
Q

Define Ventricular Fibrillation?

A

VF has obscured QRS complexes

65
Q

What are the subtypes of VT?

A

Monomorphic and Polymorphic

66
Q

What are the subtypes of Polymorphic VT?

A

Morphology that changes beat to beat, in the setting of a normal QT interval, and in the setting of a long QT interval

67
Q

What does Monomorphic VT look like?

A

A single QRS morphology/shape

68
Q

What does Polymorphic VT look like?

A

Varied QRS morphology/shape

69
Q

What does VFib look like?

A

Wide QRS complexes

70
Q

What is non-sustained VT?

A

VT that lasts less than 3 beats or 30 seconds, hemodynamically tolerated

71
Q

What is sustained VT?

A

VT that lasts longer than 30 seconds

72
Q

Which subtype of VT is more dangerous, and why?

A

Sustained VT is dangerous because it can progress to VFib

73
Q

What are the components of arrhythmia pathogensis?

A

Substrate, triggers, and modulating factors

74
Q

What factors lead to high risk arrhythmia?

A

Severe structural heart disease, such as LV dysfunction, and severe arrhythmia, such as VF

75
Q

Arrange the following arrhythias in order of severity: sustained VT, VF, Premature beats, non-sustained VT

A

Premature Beats < Nonsustained VT < Sustained VT < VF

76
Q

What are the general types of Monomorphic VT?

A

Idiopathic or associated with structural heart disease

77
Q

What are the characteristics of idiopathic Monomorphic VT?

A

Normal beats, not associated with sudden death, triggered rhythm

78
Q

What are the characteristics of the rhythm in Monomorphic VT?

A

Focal, near the Right Ventricular outflow tract, reentry with the purkinje system

79
Q

What are the causes of structural heart disease Monomorphic VT?

A

Can arise from any cardiomyopathy

80
Q

How can an infarct scar lead to sustained Monomorphic VT?

A

While the infarct leaves some areas totally unable to conduct electrical current, others can partially conduct at a slower velocity while unaffected areas are fast conducting, setting up a circuit with two pathways

81
Q

What is the treatment for Ventricular Tachycardia?

A

Implantable cardioverter defibrillator + adjunctive antiarrythmics

82
Q

Can antiarrhythmics prevent death from VT?

A

No

83
Q

When should ablation be used in VT?

A

Recurrent VT can be ablated as an adjunt to a defibrillator

84
Q

What are the subtypes of Polymorphic VT?

A

Normal QT and Long QT

85
Q

What is Torsades de Pointes?

A

Polymorphic VT in the setting of a Long QT interval

86
Q

Is Long QT syndrome congenital or acquired?

A

Long QT syndrome tends to be congenital, but may be acquired due to drugs or electrolyte abnormalities

87
Q

What are the primary causes of VFib?

A

Non-reversible causes such as cardiomyopathy and congenital electrical disorders

88
Q

What are the secondary causes of VFib?

A

Acute MI, ischemia, drugs

89
Q

What are the symptoms of VFib?

A

Syncope and Sudden Death

90
Q

Does VFib self terminate?

A

No

91
Q

What is the treatment for VFib?

A

If secondary VFib, treat cause; use implantable cardioverter device (ICD)

92
Q

How does cardiomyopathy cause VFib?

A

Cariomyopathy causes scarring, which predisposes reentry

93
Q

How do primary electrical abnormalities cause VFib?

A

They act as functional reentry

94
Q

What is a substrate in Tachyarrhythmia?

A

A structural abnormality such as an accessory pathway in AVRT

95
Q

What is an initiator in Tachyarrhythmia?

A

Substrate is always present, so an initiator causes the arrhythmia, such as premature atrial or ventricular complexes

96
Q

What are modulating factors in Tachyarrhythmia?

A

Things that alter the arrhythmia, such as electrolyte/metabolite abnormalities as well as autonomic tone

97
Q

What are the 3 requirements for a reentrant arrhythmia to emerge?

A

A potential circuit around an anatomic obstacle, an area of slow conduction, and a unidirectional block

98
Q

What is Wolf-Parkinson-White Syndrome?

A

An accessory pathway that conducts signals from the AV node to the SA Node in AVRT with a distinct ECG trace

99
Q

How can Wolf-Parkinson-white be lethal?

A

AFib rapidly conducts over the accessory pathway leading to ventricular fibrillation

Cardiovascular (25 decks)

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