ARVC

Question 1

ARVC is the most common adult-onset heart dz in what breed?

Answer 1

boxers

Question 2

what are the three forms of ARVC?

Answer 2

1) asymptomatic with VPCs
2) symptomatic with VPCs
3) ventricular dilation, systolic dysfunction, and ventricular and supraventricular tachyarrythmias

Question 3

T/F: ARVC is primarily a dz of electrical dysfunction and most echos look normal

Answer 3

TRUE, grossly most hearts look normal

10% have ventricular and atrial dilation and CHF

Question 4

ARVC is caused by a deletion mutation in what gene?

Answer 4

striatin

Question 5

T/F: all dogs with the deletion mutation in striatin gene develop ARVC

Answer 5

FALSE, it’s an autosomal dominant trait with incomplete penetrance (can have the genotype but not the phenotype)

Question 6

T/F: dogs homozygous for the deletion mutation in striatin gene usually develop a more severe form of ARVC

Answer 6

TRUE

Question 7

what is the primary site for ARVC?

Answer 7

right ventricle

Question 8

what does the histopath of ARVC look like?

Answer 8

fatty infiltration, myocyte vacuolization, myocyte loss

Question 9

what are some major effects of ventricular tachycardia that can be seen in ARVC?

Answer 9

decreases CO (not enough time for ventricle to fill) > decreases SV

loss of atrioventricular synchrony > further reduction in CO and SV

Question 10

what is the average age of boxers that are diagnosed with ARVC?

Answer 10

5-7

Question 11

T/F: ARVC can be diagnosed in boxers as young as 3 or 4 and therefore dz frequency does not increase with age

Answer 11

FALSE, though boxers can be diagnosed younger than 5-7, dz frequency and severity INCREASE with age

Question 12

what are the most common signs/presenting complaints of ARVC?

Answer 12

syncope and exercise intolerance

Question 13

T/F: sudden death may be the first sign of ARVC in some boxers

Answer 13

TRUE! primarily electrical dysfunction, majority are asymptomatic

Question 14

what might you hear when ausculting a boxer with ARVC?

Answer 14

premature beats, brief pauses, paroxysmal tachycardia

Question 15

you hear a murmur at the left heart base on a boxer. why would you need to echo this dog?

Answer 15

some boxers have benign heart murmurs, use to differentiate

Question 16

VPCs from the right ventricle are positive in what lead?

Answer 16

lead II

Question 17

does a normal ECG in a boxer rule out ARVC?

Answer 17

NO, lots of day to day variability and compared to the large number of heart beats in a day you may miss VPCs. use a holter monitor!

Question 18

you have a type III ARVC boxer. what could you see on echo?

Answer 18

dilation & systolic dysfunction (lack of robust contraction)

Question 19

when would you consider treatment for ARVC?

Answer 19

> 1000 VPCs/24 hrs (normal 0-50), runs of ventricular tachycardia, or R-on-T phenomenon

Question 20

what is the first choice in treatment for dogs with ARVC?

Answer 20

sotalol (class III anti-arrhythmic)

caution in patients w/ systolic dysfunction because can make worse in the short-term as it has some beta-blocking effects

Question 21

what drugs would you consider in treatment of refractory ventricular tachycardia?

Answer 21

combination of anti-arrhythmics or amiodarone (mostly class III but broad spectrum of classes)

Question 22

what supplements that can have anti-arrhythmic effects might you consider in adding to your treatment plan for a dog with ARVC (in addition to your anti-arrhythmic drugs)?

Answer 22

omega-3 fatty acids, DHA, EPA

Question 23

if a boxer has ARVC with concurrent systolic dysfunction what drugs should you add to the regime (other than your anti-arrhythmics)?

Answer 23

ACE inhibitors and pimobendan (+furosemide & spironolactone if in CHF)

Question 24

at what point should you recheck your patient with a holter monitor after starting drug therapy for ARVC?

Answer 24

2-3 weeks after starting a new drug or changing dose

Question 25

what is considered a positive response in regards to a holter monitor for a patient you started drug therapy for ARVC?

Answer 25

> 80% reduction in VPCs

Question 26

what symptoms are most common in a cat with ARVC (uncommon)?

Answer 26

R-CHF symptoms (tachypnea, dyspnea, jug v. distension, ascites)

Question 27

T/F: like boxers with ARVC, arrhythmias are uncommon

Answer 27

FALSE, arrhythmias (tachycardia and bradycarida) are common in cats

Question 28

what might you see in radiographs of a cat with ARVC?

Answer 28

RA and RV enlargement +/- pleural/peritoneal effusion (usually seen!)

Question 29

are echos most helpful in diagnosing ARVC in dogs or cats?

Answer 29

cats!! RV and RA dilation, aneurysmal buldge or abnormal motion of ventricular wall, systolic dysfunction, tricuspid regurgitation