Miscellaneous Arrhythmias

Question 1

What is bundle branch block?

Answer 1

Alteration in conduction of one of the bundles of His; may be structural or functional; results in a widened QRS wave

Question 2

In right bundle branch block, the R wave is ___ (positive/negative) and small, the S wave is ___ (positive/negative), and the T wave is ___ (positive/negative)

Answer 2

Positive
Negative
Positive

Question 3

In left bundle branch block, the R wave is ___ (positive/negative) and large, the S wave is (positive/negative), and the T wave is ___ (positive/negative)

Answer 3

Positive
Positive
Negative

Question 4

What are some causes of bundle branch blocks?

Answer 4

Ventricular concentric hypertrophy (HCM, HOCM, SAS)
Ventricular dilation (DCM)
Inflammation (Myocarditis, trauma, endocarditis)

Question 5

T/F: Right bundle barnch block can be normal in dogs

Answer 5

True

Question 6

Pathologically high or low levels of ___ and ___ can lead to cardiac dysfunction

Answer 6

Potassium

Calcium

Question 7

___ leads to hyperpolarization of the cell membrane

Answer 7

Hypokalemia (K

Question 8

The prolongation of repolarization that occurs with hypokalemia can lead to what problems?

Answer 8

Increased AP duration
Spontaneous ectopic activity
PVCs
Atrial PVCs

Question 9

How is hypokalemia represented on an ECG readout?

Answer 9

Prolonged QT interval
U waves
AV dissociation

Question 10

How does hypokalemia affect class I antiarrhythmic drugs

Answer 10

Causes them to be ineffective (Na channel blockers require normal serum K concentrations)

Question 11

___ leads to hypopolarization of the cell membrane

Answer 11

Hyperkalemia

Question 12

How is mild hyperkalemia represented on an ECG readout?

Answer 12

Shorter QT interval
Narrow, “tented” T waves
Sinus bradycardia expected but not often seen

Question 13

How is moderate hyperkalemia represented on an ECG readout?

Answer 13

Wide QRS complexes
Decreased R wave amplitude
Decreased P wave amplitude
Taller T waves

Question 14

How is significant hyperkalemia represented on an ECG readout?

Answer 14

Very widened QRS complexes
Prolonged PR interval
Absence of P waves

Question 15

What is sinoventricular rhythm in regards to hyperkalemia?

Answer 15

The heart beat originates in the SA node but atrial activation cannot occur; the internodal tracts carry the depolarization to the AV node and His-purkinje system

Question 16

How is severe hyperkalemia represented on an ECG readout?

Answer 16

Severely widened QRS waves
Very widened T wave
Various non-functional rhythms
Ventricular fibrillation

Question 17

How is hyperkalemia treated?

Answer 17

Remove obstruction

Fluid therapy

Question 18

How is hypocalcemia represented on an ECG readout?

Answer 18

Prolonged QT interval
T wave alternans
Lower threshold

Question 19

How is hypercalcemia represented on an ECG readout?

Answer 19

Shortened QT interval

Question 20

How is hypercalcemia treated?

Answer 20

Calcium gluconate IV

Question 21

What is a junctional rhythm?

Answer 21

Increased junctional/ventricular rate compared with sinus rate (SA and AV fire at same time)
Resembles 3rd degree AV block due to AV dissociation

Question 22

What is a good way to differentiate 3rd degree AV block from junctional rhythm?

Answer 22

3rd degree AV block - more P waves than QRS

Junctional rhythm - more QRS than P waves

Question 23

When does accelerated junctional rhythm often occur?

Answer 23

Animal is under anesthesia