ECG

Question 1

Causes for low amp. QRS?

Answer 1

Pericardial or pleural effusion, intrathoracic mass, severe pulmonary disease, hypovolemia hypothyroidism, hypothermia, acute hemorrhage, obesity

Question 2

Cause for electrical alternans

Answer 2

Pericardial effusion, intermittent aberrant conduction, ECG filtration, Brody effect: reduced QRS amplitude generated by under filled ventricles.

Question 3

Brody effect

Answer 3

When the ventricles are incompletely filled during diastole,greater tangential forces, and lesser radial forces are generated during the resultant depolarization. Brody effect explains smaller QRS with hypovolemia, afib, short coupling interval.

Question 4

Which leads show consistent t wave polarity?

Answer 4

Positive in V2 and negative in V10

Question 5

Osborne wave

Answer 5

Blip at the end of qrs at the j point. Represents hypothermia, sometimes with advance cardiac disease such as severe SAS

Question 6

Diffs for cat with large ST segment elevation?

Answer 6

Pericarditis, epicarditis, transmural/ epicardial ischemia

Question 7

Cause of phase 4 Brady dep. BBB

Answer 7

Due to spontaneous depolarization of some of the perk. Fibers

Question 8

Noise reversion. What the cause and how to fix.

Answer 8

Due to SVT.the rate is so fast that the pacemaker is not sure if the signal is real so it switches to assynchronous mode.

Treat by Shortening the Refractory Period and decrease sensitivity

Question 9

What is the wednesky effect?

Answer 9

Capture hysteresis. The threshold when measured from higher to lower volt outputs is LOWER than when measured from Low to high because of Hyperpolarization of the the myocardium of a high electrical output.

high to low»> lower threshold
Low to high»> higher threshold

Question 10

Chronaxie

Answer 10

Chyronaxie is a measurement of voltage
Defined as 2x rheobase. Rheobase is the lowest voltage when pulse width duration increases no longer results in stimulation threshold.

Question 11

Name four reasons to adjust pacemaker pulse width

Answer 11

1. Increase to capture beats with already high voltage
2. Decrease to decrease pectoral or diaphragm stimulation
3. Decrease to preserve battery life
4. Threshold testing

Question 12

Name four reasons to adjust pacemaker voltage.

Answer 12

1. Decrease to preserve battery
2. Increase to maintain capture with a high threshold
3. Decrease to reduce muscle stim
4. Threshold testing

Question 13

What is phase 3 aberrancy.

Answer 13

Tachycardia dependent BBB. The qrs terminating a pause is normal and the qrs after a shorter r-r interval is aberrant.
The longer refractory period of one of the bundle branches after the long preceding cycle ( such as a post extra systolic pause) could account for the cause.
The mechanism for this is a prolonged APD of the bundle causing a longer refractory period which prevents conduction of the next impulse.

Question 14

What is a phase 4 aberrancy?

Answer 14

Bradycardia dependent BBB. Mech: bradycardia dependent alternans may be produced by concealed spontaneous diastolic depolarization.

Question 15

What three accessory pathways and their names?

Answer 15

Kent bundle: Atrioventricular pathway aka WPW
James’ fibers: AV node bypass tract aka LGL (atria to HIS)
Mahaim fibers: nodoventricular tracts (AV to bundles, bypasses the His. Or low atria to the right bundle branch)

Question 16

What are characteristics of pre excitation?

Answer 16

Short P-R
Slurred upstroke of R wave
Wide QRS

Question 17

What is Lown Ganong Levine.

Answer 17

Short PR with normal QRS ( because James fibers use the bundle of HIS)

Question 18

Drugs to treat accessory pathways

Answer 18

Prolong the accessory pathway via class 1a or 1c.
Do NOT use dig... This will shorten the refractory period and increase firing rate

Question 19

What are 5 ways concealed conduction can manifest?

Answer 19

Prolonged PR/ alternating P-R interval 
2nd degree AVB
Displacement of the normal sinus pacemaker to another focus
Enhanced conduction
Any Combo of the above

Question 20

What is decremental conduction?

Answer 20

As the frequency of the AV node stimulation increases, the rate of conduction through the node decreases.

Question 21

Concealed conduction?

Answer 21

Atrial impulses that penetrate the AV node without conduction to the ventricles can slow the conduction of subsequent atrial impulses

Question 22

What ECG features are present in a dual AV nodal pathway?

Answer 22

During normal sinus rhythm, two distinct p-r intervals are present.