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RACP Cardio AT > Electrophysiology > Flashcards

Flashcards in Electrophysiology Deck (131)
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91

What is the progression from bifasicular to trifasicular block per year?

1% Asymptomatic
5% symptomatic

92

What is the progression from bifasicular to trifasicular block per year?

1% Asymptomatic
5% symptomatic

93

What are the two mutations associated with CPVT?

Ryanodine receptor (autosomal dominant)
Calsequestrin 2 gene (autosomal recessive)

94

What is the pathophysiology of CPVT?

Sarcoplasmic reticulum calcium release during diastole

95

What is the molecular pathophysiology of bidirectional VT?

Intracellular calcium overload

96

What are the causes of bidirectional VT?

Digitalis intoxication
CPVT

97

What is the preferred beta blocker in CPVT?

Propranolol

98

How does one achieve a unipolar intracardiac electrogram?

1. Wilson’s central terminal
2. Indifferent electrode

99

What are the features of myocardial scar on intracardiac electrograms?

Low amplitude
Fractionated

100

What pacemaker mode is required in a patient with chronic atrial arrhythmias with chronotropic incompetence?

VVIR

101

What pacemaker mode is required in a patient with paroxysmal atrial arrhythmias with chronotropic incompetence?

DDDR

102

What pacemaker mode is required in a patient with intact AV node function with chronotropic incompetence?

AAIR

But realistically DDDR in real world to ensure covering ventricular pacing if needed

103

What pacemaker mode is required in a patient with poor AV node function with chronotropic incompetence?

DDDR

104

How do you electrically detect lead insulation failure?

Impedance drops, normally <200 ohms

105

How do you identify a conductor fracture of the lead electrically?

Increased impedance >2000 ohms

106

How do you electrically localise conductor fracture of a lead?

If high impedance is found should

1. test impedance in unipolar
2 if returns to normal issue is with the anode.
3. If does not return to normal, problem is with cathode or both anode and cathode conductor wires

107

What are the causes of high lead impedance?

Conductor fracture
Bad lead connection with pacemaker block (?loose screw)

108

What are the components of the threshold of a pacemaker?

Amplitude (Voltage)
Pulse width (time)

109

What is the formula for energy?

Energy = ((voltage)2 * time) / resistance

110

To ensure adequate threshold to provide capture, is it more energy effective to increase voltage or pulse width?

Pulse width

111

What is the threshold safety margin for voltage and pulse width respectively?

2 times voltage
3 times pulse width

112

What is the safety margin for pacemaker sensing?

Half the measures impulse

113

What are the three types of upper rate behaviour?

2:1 block
Pacemaker Wenckebach
Pacemaker mediated tachycardia

114

How do you calculate pacemakers 2:1 block point?

60000/TARP

115

TARP

Total atrial refractory period

116

What is the cause of pacemaker wenckebach?

Maximum track rate (upper rate limit) delays ventricular pacing

P wave comes during PVARP resulting in “non conducting” p wave

117

What is the formula to calculate pacemaker TARP?

Atrial refractory period + post ventricular atrial refractory period

118

How can you manage upper rate behaviour?

1. Decrease TARP total duration
2. Rate response mode

119

What is the mechanism of pacemaker mediated tachycardia?

Ventricular ectopic that conducts retrograde through electrical system ultimately leading to an atrial senses beat.
This then triggers a ventricular paces beats which has retrograde conduction again etc

120

What are the conditions that must be present for pacemaker mediated tachycardia to occur?

1. Loss of AV synchrony
2. Intact V-A retrograde conduction
3. VA conduction time must be greater than the programmed PVARP