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EP lab basics CVT
Basic cardiac and EP lab principles
| Question | Answer |
|---|---|
| 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 |
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CVTMom
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