2nd degree AV block

[theunraveler]

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i got this qn here that i manage to figure out is a 2nd degree AV blockage but i am not sure if its a type 1 or type 2 so i'm kinda asking for help here 😀...but anyway here it goes...my 5 min vet consult textbook isnt much help 🙁

"There is a distinct first (S1) and second (S2) heart sound without signs of murmurs or splitting but the S1 to S1 interval is erratic and irregular. The heart rate is slightly low but not sufficient to class it as a bradychardia. Palpation of the carotid shows that the pulse rate matches the heart sounds. There is no sign of oedema or jugular distention. The owner has not noticed increase in tiredness of the cat, although there may be a reduced frequency of exercise"

 

[AuburnPreVet]

Type 1 (Mobitz 1) is characterized by lengthening of the P-R interval, eventually leading to a "dropped beat" meaning a P wave without a corresponding QRS wave.

Type 2 (Mobitz 2) you simply have a "dropped beat" without the progressively lengthening P-R interval.

That still doesn't answer your queston without an EKG lead. Just curious as to how you came to think 2nd degree AV block with the given info? Not a whole lot of info there.

 

[chris03333]

That still doesn't answer your queston without an EKG lead. Just curious as to how you came to think 2nd degree AV block with the given info? Not a whole lot of info there.

That's exactly what I was thinking...😕

 

[theunraveler]

i'm not sure actually but thats the general feeling from my class and we all kinda think its AV block...could be type 1 or 2 but we wont know till ECG is done

 

[Maverick007]

Hey good peoples,

Got this question ...

"There is a distinct first (S1) and second (S2) heart sound without signs of murmurs or splitting but the S1 to S1 interval is erratic and irregular. The heart rate is slightly low but not sufficient to class it as a bradychardia. Palpation of the carotid shows that the pulse rate matches the heart sounds. There is no sign of oedema or jugular distention. The owner has not noticed increase in tiredness of the cat, although there may be a reduced frequency of exercise"

Class is torn between sinus arrythmia (maybe with wandering pacemaker) and AV block

The 'erratic' bit is throwing us. Any ideas?

 

[Angelo84]

I agree you need an EKG. I would be leaning toward AV block given the info. Sinus arrhythmia is physiologic in horses and dogs at slow heart rates. I don't think cats can have a slow enough heart rate to have SA without being bradycardic. Also sinus arrhythmia isn't really erratic it varies but it does so consistently. AV block would lead to a more erratic interval in my mind. As far as type 1 or 2 need an EKG....

 

[ovc2012]

I also agree that we need an ECG to look at this. Given that there is a slow rhythm, does the ECG show a P wave?

If no P wave: then hyperkalemia or persistent atria standstill

If yes P wave: then do QRS complexes have associated P waves?

If yes: then sinus bradycardia or 2nd degree heart block
If no: then 3rd degree heart block

So since you said that it's not sufficient for bradycardia, it's either 2nd or 3rd degree heart block. It could be a mobitz 2, 2nd degree heart block because for a mobitz 2 heart block there is possibly evidence of reduced CO if the ventricular rate is substantially reduced.

For a 3rd degree heart block, generally, the atrial rate is fast and regular and ventricular rate is much slower than atrial rate (can see that on ECG) - just look at the different leads.

But in the end, really, we need an ECG...I don't really think there's sufficient information?? :S

 

[bern]

CAL UPenn (http://cal.vet.upenn.edu/) has a great cardiology site with EKG tutorials. I mooch off their online resources all the time.