EP

Question 1

What are the surface tracings in an electrogram?

Answer 1

Leads I, II, and V1 = surface tracings recorded at a speed of 100 mm/sec (faster than speed of surface ECG which is 25 mm/sec)

Question 2

What is HRAd on an electrogram?

Answer 2

HRA d –> High RA placement

• represents electrical activity as it traverses the distal electrodes of the catheter placed in the high RA (HRA)
• corresponds to P wave on surface electrograms

Question 3

What are the HISp and HISm on the intracardiac electrogram?

Answer 3

• HIS p and HIS m
• obtained from electrodes located at proximal and mid portion of the HIS bundle catheter
• first/largest deflection of HIS p represents atrial activity at the distal portion of the atria
• low amplitude, broad signal = ventricular activation, corresponds with QRS on surface tracing

Question 4

What is HISd on the intracardiac electrogram?

What does it represent?

Answer 4

• HIS d = distal HIS electrode position
• 3 electrograms for each P-QRS complex
  • first = largest and corresponds to P wave
  • second = sharp signal, represents HIS bundle activation
  • third = ventricular activation in the septum occurring just below tricuspid valve

Question 5

What is RVa tracing on the intracardiac electrogram?

Answer 5

RVa = electrical activity traversing the RV apex

Question 6

Which electrogram tracing can measure conduction across the AV node?

Answer 6

HIS bundle catheter (HIS p, m, d)

-AH time can be measured from the low RA recording (HIS p) and the bundle electrogram (HIS m, d)

Question 7

What is normal AH interval?

What is AH interval?

Answer 7

• 45-140 msec
• Conduction time through the AV Node.
• measurement is obtained by evaluating the time between the Atrial and His bundle electrograms on one of the His catheter recordings.
• dependent on patient’s age and autonomic state

Question 8

When is a short AH interval seen?

What does it suggest?

Answer 8

• children and adults “juvenile AV node”
• brisk AV nodal conduction

Question 9

When is a long AH interval seen?

What does it suggest?

Answer 9

• slow AV nodal conduction
• Causes:
  
  • fibrosis due to CAD or senile degeneration
  • AV nodal blockade (BB, non-dihydrpyridine CCB’s)
  • High Vagal Tone

Question 10

How is the HV interval measured?

Answer 10

measured from the beginning of the HIS bundle electrogram recording (second deflection on the HIS bundle catheter during sinus rhythm) to the first ventricular electrogram either on:

• the HIS bundle recording (the third deflection in sinus rhythm)

or

• RV electrogram

or

• even on any of the surface QRS recordings.

Question 11

What does HV measure?

Answer 11

• represents distal conduction activation
• conduction time from the His bundle (located just below the AV node) –> first identifiable onset of ventricular activation.
• the time it takes for an electric impulse to traverse the HIS bundle, the bundle branches, and the Purkinje network in order to activate the ventricles

Question 12

Describe the measurement

Answer 12

• measurement of HV interval
  
  • from beginning of His bundle recording to the first ventricular electrogram
• HV = 90 msec –> prolonged
  
  • normal HV = 25-55 msec
• Patient with first-degree AV block and RBBB on surface ECG

Question 13

What is a normal HV interval?

Describe the HV interval?

Answer 13

• 25-55 msec
• conduction time from the His bundle (located just below the AV node) –> first identifiable onset of ventricular activation.
• normal HV interval is not affected by autonomic state or pharmacologic agents

Question 14

What does a short/negative HV interval suggest?

Answer 14

• ventricular activation occurs before HIS bundle activation
  
  • Accessory pathway (WPW)
  • VT

Question 15

The site of AV block may be determined by this?

Answer 15

• His bundle electrogram
  
  • determines AV node vs. distal conducting system blocks

Question 16

What does a prolonged HV interval suggest?

Answer 16

• abnormal conduction in the distal cardiac conduction
• portends a higher likelihood of conduction failure –> heart block

Question 17

What two medications can be used to reduce the risk for ICD shocks in VT?

What trials demonstrated this?

Answer 17

• Sotalol and Amiodarone
• OPTIC - 2005 (Optimal Pharmacological Therapy in Cardioverter Defibrillator Patients) study.
• Amiodarone (+ BB) superior to Sotalol

Question 18

Sotalol:

• MOA
• Major side effect
• Elimination

Answer 18

• MOA:
  
  • IKr blockade - delayed-potassium rectifier channel
  • Beta receptor blockade (predominant action at doses < 160 mg daily)
• Side effects
  
  • Torsades de pointes < 2%
    
    • increases in setting of bradycardia, female gender, pre-excisting QT prolongation, history of heart failure, VF, VT, hypokalemia
    • Avoid in combination with QT prolonging agents
• Elimination:
  
  • Kidney 100%
  • No pharmacologic interaction with warfarin, digoxin HCTZ

Question 19

What is the difference in survival, in refractory VF patients comparing Lidocaine and Amiodarone?

Answer 19

• ALIVE trial - 2001 (Amiodarone vs. Lidocaine in Prehospital VF Evaluation) compared the two in treatment of Cardioversion refractory VF in the field.
• Amiodarone demonstrated improved survival (2:1) to hospital admission
• No difference in survival to hospital discharge

Question 20

What arrhythmia most likely in a patient with Ebstein’s anomaly? How would it manifest?

Answer 20

• AVRT
• likely related to bypass tract –> manifests as pre-excitation

Question 21

What did the AVID trial show?

What population of patients were included and benefit from ICD over antiarrhythmics?

Answer 21

• AVID - 1997 (Antiarrhythmics Versus Implantable Defibrillators) in patients with history of Ventricular Arrhythmia
• Secondary prevention (class I indications)
• VF arrest (resuscitation)
• Sustained VT with syncope
• Sustained VT with an LVEF < 40% associated with severe symptoms (HF, angina)

Question 22

What is the treatment for inappropriate ICD shock that occurs due to a supraventricular arrhythmia?

Answer 22

• Elimination of VT zone (170 bpm) –> single-zone program strategy (VT/VF = 200 bpm) led to reduction in inappropriate therapies and improved survival
• MADIT-RIT (Multicenter Automatic Defibrillator Implantation Trial - Reduce Innappropriate Therapy)

Question 23

What are the Class I indications for ICD?

Answer 23

1. Survivors of cardiac arrest due to sustained VT or VF, not due to a reversible cause
2. Spontaneous sustained VT in the setting of structural heart disease.
3. Syncope of unknown cause with induction of sustained VT (or VF) that is hemodynamically significant.
4. Prior MI ( > 40 days earlier) with LVEF < 35% and NYHA functional class II-III heart failure.
5. NICM with LVEF < 35% and NYHA functional class II-III heart failure.
6. Prior MI ( > 40 days earlier) with LVEF < 30% and NYHA functional class I heart failure.
7. Spontaneous nonsustained VT, prior MI with LVEF < 40%, inducible sustained VT (or VF).

Question 24

What are complications of CIED placement?

Answer 24

• Infection
• Hematoma (pocket)
• Hemothorax
• Pneumothorax
• Pericardial effusion/tamponade from lead perforation
• Lead dislodgement
• Extracardiac stimulation (phrenic, diaphragmatic, other)
• Thromboembolism
• Arrhythmias (including inability to convert induced VF)
• Anesthetic risks
• Death

Question 25

What clinical circumstances preclude use of a S-ICD?

Answer 25

* CRT * Antitachycardia pacing support * Bradycardia pacing support

Question 26

What subset of patients require S-ICD?

Answer 26

* Vascular access limitations * HD pateints * Prior lead extraction

Question 27

What are Class IIa indications for ICD?

Answer 27

1. Syncope of unknown origin in the setting of NICM with significant LV dysfunction 2. Spontaneous sustained VT in the setting of normal or near normal LV function (excludes VT amenable to ablation with structurally normal heart) 3. Hypertrophic cardiomyopathy with \> 1 risk factor for sudden death in that disease state. 4. Arrhythmogenic right ventricular cardiomyopathy/dysplasia with \> 1 risk factor for sudden death in that disease state. 5. Long QT syndrome with syncope (or polymorphic VT) despite beta-blockers. 6. Patients awaiting cardiac transplantation as an outpatient. 7. Brugada syndrome and syncope. 8. Brugada syndrome and documented VT. 9. Catecholaminergic VT and syncope or VT. 10. Cardiac sarcoidosis, giant cell myocarditis, or Chagas disease.

Question 28

What are Class IIb indications for ICD?

Answer 28

1. NICM with LVEF \< 35%, and NYHA functional class I heart failure. 2. Long QT syndrome with established high-risk features. 3. Syncope of unknown origin in the setting of significant structural heart disease. 4. Familial cadiomyopathy associated with sudden cardiac death. 5. Patients with noncompaction cardiomyopathy.

Question 29

What does SNRT measure?

Answer 29

- Sinus Node Recovery Time - measures spontaneous recovery of the sinus node after overdrive suppression - Normal uncorrected SNRT \< 1400 ms - Nromal corrected SNRT \< 550 ms -

Question 30

What are the criteria for Left Anterior Fascicular Block (LAFB)?

Answer 30

* LAD (usually between -45 and -90 degrees) * Small Q waves with tall R waves ( = 'qR complexes') in leads I and aVL * Small R waves and deep S waves ( = rS complexes) in leads II, III, aVF * QRS duration normal or slightly prolonged (80-110ms) * Prolonged R wave peak time in aVL \> 45ms * Increased QRS voltage in the limb leads

Question 31

Answer 31

* Atrial fibrillation * Left anterior fascicular block * LAD * qR in I and aVL * rS in II, III, aVF * QRS normal or slightly prolonged (80-110ms) * Prolonged R wave peak time in aVL \> 45ms * Increased QRS voltage in limb leads * Nonspecific ST and/or T wave abnormalities

Question 32

What are common arrhythmias associated with Digoxin toxicity?

Answer 32

* atrial tachycardia * atrial fibrillation with complete heart block * accelerated junctional rhythm * AV block (2nd or 3rd degree) * Bi-directional VT \*\*exacerbated by hypokalemia, hypomagnesemia, hypercalcemia

Question 33

Answer 33

Digoxin toxicity * atrial tachycardia * AV block 2:1 * exacerbated by hypokalemia, hypomagnesemia, hypercalcemia

Question 34

What is functional (rate-related) aberrancy?

Answer 34

* mean QRS duration greater than 120ms in the setting of rapid heart rates, but returns to normal duration at slower heart rates

Question 35

What is the mechanism of PAC's?

Answer 35

* typically will conduct back to the SA node --\> resetting the node --\> temproarary pause * if SA entrance block exists (preventing conduction back to the SA node) --\> node will not reset and either: * interpolated beat (extra QRS complex between otherwise constant R-R intervals) * full compensatory pause

Question 36

Define RBBB

Answer 36

* QRS \> 120ms * RSR' pattern in V1-V3 * Wide slurred S wave in I, aVL, V6 (S wave greater duration than R wave or \> 40 ms) * R wave peak time \>50ms in V1

Question 37

A clinical diagnosis of HCM is confirmed when these features are identified.

Answer 37

* Increased LV wall thickness ( 13-60mm, average 22mm) * Nondilated LV chamber

Question 38

What is the most common location for LV hypertrophy in HCM?

Answer 38

basal anterior septum in continuity with the anterior free wall

Question 39

What is the pathology for HCM? What is the characteristic histopathologic finding?

Answer 39

* Abnormal intramural coronary arterioles --\> decreased luminal cross-sectional area and impaired vasodilatory capacity --\> blunted myocardial blood flow during stress (small vessel ischemia) --\> myocyte death --\> fibrosis * Disorganized and chaotic pattern of **Interstitial Fibrosis**

Question 40

What are the noninvasive clinical risk markers that can help identify HCM patients at high-risk for SCD / indication for ICD?

Answer 40

* Hypotensive or attenuated BP response to exercise * Extreme LV hypertrophy (wall thickness \> 30 mm) * Family History of premature HCM-related death (particularly if sudden death in close relatives) * Unexplained Syncope judged non-neurocardiogenic, particularly if recent, in young patients * NSVT on serial ambulatory EKG's, particularly when bursts are multiple, repetitive, or prolonged Subgroups who should also be considered for ICD \*\*LV apical Aneurysm \*\*LVEF \< 50% \*\*\*LGE \> 15% of LV mass \*\*\*Cardiac arrest/sustained VT

Question 41

What does LGE identify in HCM? What level indicates high-risk for SCD / ICD placement?

Answer 41

* Degree of myocardial fibrosis * \> 15%

Question 42

What is the only proven therapy to prevent SCD in HCM patients?

Answer 42

ICD

Question 43

Answer 43

Pre-excitation * indicating a bypass tract

Question 44

Describe use of "pill-in-the-pocket" What medications are used for this?

Answer 44

* Initial rate control to prevent rapid conduction of A-fib/flutter * BB or CCB * Followed by administration of a single bolus dose of a class I antiarrhythmic drug * Flecainide 200-300 mg * Propafenone 450-600 mg

Question 45

What are contraindications to "pill-in-the-pocket" (or class Ic antiarrhythmics) approach?

Answer 45

* Structural heart disease * Conduction system disease (bundle branch block)

Question 46

Describe the findings

Answer 46

**4:1 rate controlled atrial flutter** * no additional intervention required prior to surgery

Question 47

Describe the findings

Answer 47

**Delayed afterdepolarizations** * PVC's with left bundle morphology and inferior axis ---\> **focus at the RV outflow tract**

Question 49

What is a cause of delayed afterdepolarizations: * young adult without structural heart disease

Answer 49

PVC's arise from triggered activity due to **catecholamine-induced delayed afterdepolarizations**

Question 50

What percentage of patients are LAA thrombi found in patients with AF \> 2 days?

Answer 50

5-14%