Catheter positions, EGMs & intervals
Catheters
Catheters come with a variation of different electrodes, where the most distal tip is universally refferred to as electrode 1, everything proximal is labelled in progressive order (e.g., 2, 3, 4) for the length of th catheter.
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Each catheter can sense and be paced from.
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There are
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Quadpoles (4)
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Hexpoles (6)
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Decapolars (10) and
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Duodecapolars (20)
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There are also high definition (HD) catheters that may involve multiple rows and configurations of electrods with different labelling.
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CLICK HERE FOR MORE INFORMATION ON HD MAPPING CATHETERS
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There catheters come in different shapes which are designed to be used in different anatomical regions.
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Some catheters are passive, while others are steerable
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The type of case will determine which and how many catheters will be used. This will be varied from each different consultant and is dependent on preference.
There are multiple ablation techniques which involve different catheter types across each manufacturer.
Quadripolar (top) & decapolar (bottom) catheters
Electrograms (EGMs)
Depending on which catheters will be used will affect the diplay set up of EGMs.
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The usual sweep speed of an EP study is typically a lot faster (usually 100-150) than a 12 lead ECG (25).
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The display screen usually has a select few ECG channels at the top of the page.
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The electrode signals are then displayed in groups (e.g., HIS signals together, CS signals together).
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Electrodes are paired (bipolar) to an electrode in close proximity on the same catheter (e.g., CS1 to CS2)
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Depending on the Consultant involved, these signals will be displayed top down in either a proximal-distal or distal to proximal fashion (see example below)
Basic intervals
ECG intervals
PR: 120-200
QRS: 60-120
QT: 380-440
QTc: 350-450 (m)
QTc: 360-460 (f)
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EGM intervals
AVN conduction time
AH: 55-140
HIS bundle conduction time
HV: 35-55