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EP lab basics CVT

Basic cardiac and EP lab principles

QuestionAnswer
How are EP catheters different from Cath-lab catheters? Solid core with multiple electrodes
What is determined in EP lab? Baseline intervals and effects of altering conduction initiation
What is assessed in the EP lab? SA node, AV node, Bundle of His, and Purkinje Fibers
What is "mapping"? Finding the location of arrhythmia foci for ablation therapy
Complications of EP testing are ABC IT- Arrhythmias, Bleeding, Cardiac perforation, Infection (local or systemic), Thrombo-embolism (pulmonary)
What are the bleeding complications? Bleeding HAPpens: Hematoma, A-V fistula, Pseudoaneurysm
What is withheld before the study in patient preparation? Medications, ESPECIALLY anti-arrhythmics
What is least likely to occur in the EP lab? Myocardial Infarcts
Which catheter is presented in profile in the LAO projection? Coronary sinus
Are sheaths placed in the arterial or venous system in the EP lab? Venous, 2 or more sheaths per vein.
Where do most v-tachs occur? RVOT
Where are catheters placed? HRA (high right atrium), BOH (Bundle of His), RV apex (or RVOT), Coronary Sinus (& RV apex)
If you were studying SVT's, where would you place the catheter? Coronary sinus and RV apex
If pacing of the RV is required, where would you place the catheter? RVOT, right ventricular outflow tract
What is achieved by inserting the catheter into the coronary sinus? Pacing and recording of the LA
Where is the coronary sinus located? Posterior and slighly inferior to the tricuspid valve.
What does the coronary sinus catheter evaluate? LA depolarization
What three beats does the HIS catheter record? Atria, BOH, right ventricle. A, AH, V
What does lead I show? Provides visualization of right to left activation
What is seen using lead aVF? High to low activation
Activation of what is seen in lead V1? The Bundles of His
What do catheter hookups start with proximally? High numbers
What numbers are found distally on the Coronary sinus catheter? Low numbers, 1, 2, 3, etc
What is the sweep speed of EGMs? 100mm/sec
Where does the coronary sinus catheter sit? Between the LA and the LV
Which intra-cardiac tracing shows the initiation of atrial depolarization? A
His Bundle activation is illustrated by what letter? H
Ventricular deploarization is noted by what letter? V
AH+HV=? PR-Interval
What are the functions of the EP catheters? Record activity & Pacing abilities
What do surface ECGs demonstrate? Sum of all cardiac activity
EP catheters are filtered so that what phase of the action potential is seen at specific electrodes? Zero
Premature impulses are introduced in order to ... *Measure refractory periods * Assess conduction properties of tissue, * Assess automaticity * Study reentrant circuits
First premature beat following a pacing chain is labeled what? S2
What landmarks surround the Triangle of Koch? Eustachian valve, Oval fossa, Tendon of Todaro, Tricuspid valve
What is located within the Triangle of Koch? The Coronary Sinus
Normal Range of Cycle Length (CL) 1000-600 ms (60-100 bpm)
AV nodal conduction interval range (AH) 50-120 ms
His-Purkinje conduction (HV) 35-55 ms
Sinus node to ventricles interval range (AV) 120-200 ms
Interval range for ventricular depolarization 80-110
Ventricular repolarization (QT) <500 ms
First Premature beat following a pacing chain is labeled? S2
Escape rhythms are the result of? Failure of impulse generation
Three areas of activity visualized by the HIS catheter? A - Atria, H - His Bundle, V - Ventricle
Structure closest to the septum in the Triangle of Koch? Tendon of Todaro
The two valves separated by the Triangle of Koch? Eustachian valve and Tricuspid Valve
Where is the coronary sinus located? Within the Triangle of Koch in the right atrium
The closed conduit in the right atrium near the Eustachian valve Oval fossa
Conduction Movement of impulse from structure to structure or cell to cell
Refractory Period Period of time wen cell/structure is not able to produce or transmit impulse
Response of cardiac tissue to premature stimuli Refractoriness
Refractory Performed through pacing several beats followed by premature stimuli at progressively shorter intervals
Heart blocks are the result of what? Failure of impulse propagation (conduction)
Many brady-arrhythmias are treated how? Pacemaker insertion
Three causes of tachy-arrhythmias Triggered activity Re-entry beats/rhythm Enhanced automaticity
Which cause of tachy-arrhythmias cannot be evaluated in the EP lab? Enhanced automaticity
Example of enhanced automaticity Inappropriate sinus tach (IST)
How are tachy-arrhythmias treated? Pharmacology, ablation, over-ride pacing
What vessel if blocked, would disrupt the SA & AV nodes? RCA
Automaticity disturbances are seen in which phase of the action potential 4 - the resting phase due to leakage of ions across the membrane leading to gradual change in voltage.
Causes of Automaticity disturbances Metabolic (kidneys), ischemia, electrolyte deficiency, acid-based disorders. Could be d/t blockage
Tachy-arrhythmia not inducible so unable to be evaluated in the EP lab? Enhanced Automaticity
Has features of both automaticity and re-entry abnormalities making it hard to distinguish in the EP lab Triggered activity
How is Triggered tach similar to Automaticity tach? Leakage of ions creating rise in action potential
"Afterdepolarizations" are noted in what phase of the action potential? Late 3 early 4
Likely cause of SVTs Triggered tach
Triggered tach is thought to be the mechanism of action for what? Torsades de Pointe
Introduce premature stimuli delivered in predetermined patterns and timed intervals Fixed cycle lengths
Bidirectional conduction with unidirectional block Re-entry Tach
Common cause of arrhythmias and extremely dangerous Re-entry circuit disturbances
What kind of bypass tracts do re-entry tachs have Dual SAN or AVN and AV
Results in reentrant VT Scar tissue d/t MI or cardiomyopathy
Re-entrant tach can be acquired through the development of Cardiac disease states
Alpha re-entry conduction Slow conduction - short wake
Beta re-entry conduction Fast conduction - long wake
Premature beats can follow a _______ conducted beat more closely than a ____________ conducted beat Slowly - Rapidly. Just as slow boats can follow more closely
Normal atrial impulses reach AVN through Beta pathway (Fast conduction/long refractory)
Slow conduction = a longer PRI
Faster conduction = a shorter PRI
If a premature atrial impulse finds the Beta pathway refractory and the Alpha pathway not, what will happen? Impulse will take Alpha pathway and increase the PRI
Results in paroxysmal SVT Impulse traveling retrograde up Beta and down Alpha
This often PRECEDES a P-SVT Long PRI
Results in a long PRI Alpha pathway
Results in a short PRI Beta Pathway
Termination of Re-entry Overdrive pacing, Pharmacology, Ablation
What does pharmacology do to the action potential? Alters the "0" phase shape and/or refractory periods
Permanent termination of a re-entry stimuli Ablation
Locations of Accessory Pathways Anterior/Posterior/ Right Free-wall/ Left Free-wall
Pathway closest to Anteroseptal pathway Right Freewall
Anteroseptal pathway is between which valves MV & TV
Pathway separating Left and Right Freewalls Posteroseptal pathway
Pathway below the non-dominate Aortic Valve cusp Anteroseptal pathway
The septal pathway that is the largest Posteroseptal
Non-conductive ridge along the lateral wall of the RA Crista Terminalis
Bypass tract that conducts ANTEGRADE is said to be Wolff-Parkinson-White (WPW)
Pre-excitation of the QRS is called ____ and seen in ____ Delta wave / WPW
A delta wave is evidence that ventricle was stimulated prematurely
Antegrade conduction that stimulates the ventricle prematurely is noted by A delta wave on the QRS
An impulse traveling over a bypass tract does not experience ___ as a normal impulse traveling through the _____ Delay / AV node
Pre-excitation is usually manifested by Short PRI/ slurring of the QRS complex
The slower the AV nodal conduction the larger the delta wave
Four types of bypass tracts A - Kent's Atrial muscle to ventricular muscle B - Low atrial tissue near AVN connecting to HIS-Purkinje C- Mahaim AVN connected to Right Bundle Branch (AVN-RBB) D- HIS-Purkinje fibers to ventricular myocardium
What is at the tip of the Triangle of Koch, closest to the septum? The Bundle of His
Intra-Atrial Conduction Time (PA) 20 - 30ms
Coupling Interval Time between LAST NORMAL impulse (S1) and first PREMATURE/PACED impulse at end of pacing chain (S2) Coupling Interval
Introduction of PREMATURE beats into rhythm at PRECISELY TIMED intervals Programmed stimulation
Programmed stimulation delivered in predetermined patterns at precisely timed intervals Fixed Cycle Lengths
Introducing a train of paced beats at fixed cycle lengths Incremental Pacing
Types of Programmed stimulation Incremental pacing and extra stimulus pacing
Introducing extra-stimuli at a shorter length than the pacing chain (usually 8 beats long) or the patients intrinsic rhythm Extra stimulus pacing. S1= Last intrinsic or paced beat S2= first extra stimuli S3= next extra stimuli
The "P" wave is inverted when stimuli takes place in The middle of the heart as in a Junctional waveform
In atrial pacing, the SAN is evaluated for Automaticity and Conductivity
When pacing the atria, the AVN and HIS-Purkinje is evaluated for Conductivity and refractoriness
When do we attempt to induce atrial arrhythmias? Atrial Pacing
Retrograde conduction (ventricle to atria) is assessed during Ventricular pacing
During ventricular pacing we attempt To induce ventricular arrhythmias
When do we assess potential for drug effect? During atrial or ventricular pacing
In the EP lab we cannot assess automaticity disturbances but we can evaluate SAN or AVN automaticity. How? Paced at faster-than-normal rate
Pacing at faster than normal rate is called? Overdrive suppression
What are you doing with overdrive suppression? Trying to wear out the heart to measure how long it takes to recover
When overdrive suppression pacing is stopped, there is often a relatively _____ pause before node _____ and spontaneously ____ an impulse long / recovers / generates
A longer than normal recovery time indicates A disease process is present
Short recovery time after overdrive suppression pacing indicates No disease is present
Potentially fatal bradycardic arrythmias, such as escape rhythms, heart block, etc is resultant to Poor automaticity
Measurement of the period of time when no stimulus regardless of intensity will produce stimuli Absolute Refractory Period
When is an action potential in absolute refractory period? Time from onset of action potential until about midway down phase 3 of action potential.
The absolute refractory period is difficult to measure so what period is used? Effective Refractory Period
Why would a premature impulse fails to propagate through tissue demonstrating the longest coupling interval? The tissue is refractory
Long effective refractory period (ERP) is due to Slow conduction time
Faster conduction time is due to a Shorter effective refractory period (EFP)
Measurement of how rapidly a structure can conduct form itself to another (i.e. AVN to BOH) Functional Refractory Period
Functional Refractory period is measured how Pacing proximal structure at progressively faster rates until no signal reaches distal structure
Functional Refractory Period is shortest interval between successive impulses were impulse reached distal structure
Functional RP Conduction
Created by: CVTMom