deck 2

Question 1

Which EKG factors are associated with higher risk of SCD in patient who is s/p acute MI? (2)

Answer 1

1. NSVT
2. loss of beat-to-beat variability (aka NO sinus arrhythmia)

Question 2

Which rhythm will you code for this rhythm strip?

Answer 2

NSR with mobitz I, 2nd degree AVB

• when Wenchebach is present on any portion of the EKG, the underlying block is more likely INTRAnodal → code mobitz 1

Question 3

Which two items should be coded for a patient with complete heart block?

Answer 3

1. 3rd degree AV
2. AV dissociation

Question 4

Differential diagnosis of paced ventricular beats with RBBB morphology? (3)

Answer 4

pathologic cause: RV lead pacing the LV apex (perforation of interventricular septum)

idiopathic causes:

• LV epicardial lead
• LV coronary sinus lead (biV pacer)

Question 5

Name 3 reasons why a pacemaker might pace on a T-wave (undersensing)

Answer 5

• pseudo-undersensing (do not code PPM malfunction)*: APC or PVC falls in programmed refractory period and is thus not sensed
• true undersensing (PPM sensing malfunction should be coded)* → may be caused by:
• PPM programming problem (depolarization is of insufficient amplitude to be sensed)
• PPM hardware problem

Question 6

Definition of PPM malfunction, capture failure (2)

Answer 6

both must be present:

1. Pacing spike NOT followed by appropriate depolarization
2. pacing spike occurs when myocardium is NOT refractory (aka no pseudo-malfunction present)

Question 7

What is “pseduo-capture malfunction”

Answer 7

PPM stimulus falls into refractory period of ventricle→ failure to capture

Question 8

differential diagnosis of PPM malfunction, failure to capture? (7)

Answer 8

hardware problem

• lead displacement (e.g. perforation)
• battery depletion (pulse gen failure)
• lead insulation break (w/ or w/out fx)

chemical problem → increased pacing threshold due to:

• ARD therapy (flecainide, amio)
• acute MI
• hyperkalemia

iatrogenic → inappropriate programing

Question 9

Pt with PPM sees you for interrogation. Rhythm strip is shown below. What’s the diagnosis?

Answer 9

myopotential inhibition (aka oversensing of myopotentials)

• oversensing with high-frequency background noise during pause → think of myopotential inhibition

Question 10

Pt with unipolar PPM p/w presyncopal symptoms. What to do next?

Answer 10

interrogate the device to look for myopotential inhibition

​* myopotential inhibition is more common in unipolar pacemakers

Question 11

What’s the diagnosis?

Answer 11

oversensing of T waves

• think of above when see tall T-wave followed by pause that is equal to paced RR interval

Question 12

Pt with palpitations and rhythm strip below. Diagnosis?

Answer 12

pacemaker-mediated tachycardia

• A-sense, V-paced at programmed upper limit (~120 bpm) → think of PMT

Question 13

how to treat pacemaker-mediated tachycardia?

Answer 13

increase the PVARP (post-ventricular atrial refractory period)

Question 14

What’s the diagnosis?

Answer 14

dextrocardia

EKG criteria for dextrocardia → need both of the following;

• P-QRS-T inversion in high lateral leads
• reverse R-wave progression in precordial leads

Question 15

In which leads are Q waves considered normal? (2)

Answer 15

III and aVR