Cardio Review 4 Flashcards
Delayed conduction through AV node
1* AV block
What ECG characteristics will you see with 1* AV block?
Consistently prolonged PR, normal QRS
What is the most common cause of 1* AV block?
High vagal tone
What drugs can cause a 1* AV block?
Digoxin, a2 agonists
How do you treat 1* AV blocks and mobitz type 1 2* AV blocks?
Tx underlying cause
Conduction through AV node is stopped but only transiently
2* AV block
What ECG characteristics will you see w/2* AV block?
Some P waves do not have QRS after them, normal QRS
What additional ECG characteristics are assoc. w/mobitz type 1 2* AV block?
Prolonged PR prior to block
What does high grade mobitx type 2 2* AV block cause?
Bradycardia
What is the most common cause of mobitz type 1 2* AV block?
High vagal tone
What e-lyte imbalance can cause mobitz type 2 2* AV block?
Hyperkalemia
What is the most common cause of mobitz type 2 2* AV block?
Structural AV node disease
How do you treat high grade mobitz type 2 2* AV block and 3* AV blocks?
Pacemaker, dopamine, theophylline
Conduction through AV node is permanently stopped
3* AV block
No impulses are able to travel from the atria to the ventricles
3* AV block
What ECG characteristics will you see with a 3* AV block?
P waves w/o QRS, escape beats
What e-lyte abnormality can cause 3* AV blocks?
Hyperkalemia
How do you ddx a bundle branch block from a ventricular arrhythmia?
BBBs have AV association
What ECG characteristics will you see with a BBB?
Wide QRS
Delay in conduction/lack of conduction in the bundle branches
Bundle branch block
QRS is negative in lead II with which BBB?
R-BBB
QRS is positive in lead II in which BBB?
L-BBB
What are the most common causes of BBBs?
Idiopathic in some dogs, structural heart disease
Absence of atrial depolarization
Atrial standstill
What ECG characteristics will you see with atrial standstill?
No P waves/fibrillation/flutter, normal QRS
What e-lyte abnormality can cause atrial standstill?
Hyperkalemia
How do you treat atrial stnadstill?
Pacemaker, dopamine, theophylline
Atrial standstill can be caused by a neuromyopathy in which dog breed?
Springer Spaniel
Which dog breed is most predisposed to sick sinus syndrome?
Mini Schnauzer
What causes sick sinus syndrome?
Idiopathic: normal SA node cells replaced by fibrous tissue
This e-lyte imbalance prolongs repolarization (VPCs/APCs) and lowers resting membrane potential
Hypokalemia
This e-lyte imbalance can cause absent P-waves, long PR, V-fib, and PEA if severe
Hyperkalemia
This mineral is essential for enzymatic reactions and is involved in postassium regulation
Magnesium
Which mineral affects skeletal muscle more than cardiac muslce?
Calcium
Which e-lyte imbalance causes decreased action potential threshold (sizures) and long QT?
Hypocalcemia
Which e-lyte imbalance causes increased AP threshold, bradycardia, short QT, and VPCs?
Hypercalcemia
