Most Common arrhythmias in smalls Flashcards
(41 cards)
Ventricular Extrasystoles (VPC)
- HR: normal, low or high i.e irregular!
- Rhythm: irregular due to the premature beat
- P-waves: not associated with P waves (except fusion beat). The normal sinus P-waves may distort the ST segment or T-wave of extrasystole!
- QRS: WIDER AND LARGER
- ST-segment: abnormal
- T waves: abnormal, OPPOSITE POLARITY TO THE QRS
- Pause: fully compensated, no resting
VPC left ventricular origin
**look at direction of QRS complexes
Large (-) deflection
Large (+) P waves
VPC right ventricular origin
Producing (+) waves that are wider and larger than simus waves
Ventricular tachycardia (many extrasystoles)
Sustained vs non-sustained
Uniform vs multiform
Accelerated idioventricular rhythm
Torsade de pointes
Flutter, fibrillation
What 2 features are ALWAYS seen with ventric tachycard?
- A captured sinus beat- when you see the sinus firing at the correct moment
- Fusion beat- combo of sinus and the ventric originating ectopic beat. The depol is coming from 2 direstions
May have to wait some time before you eill see the 2- but you will always see the 2
Accelerated idioventricular ryhthm
Most commonly the HR<160bpm with this
Therefore often known as slow ventric tachycard
The slow HR is convenient as it allows us to see the sinus beats and fusion beats
Torsade de pointes
Means “changing of the points”
from (+) to (-)
Multiform, v. fast ventric tachycard
Emergency situation
Ventricular flutter, fibrillation
Flutter= reentry
Fibrillation=disorganised beats
Causes of ventric arr
Cardiac
Extracardiac
Drugs/toxins
Cardiac causes of ventric arr
Myocardial injury
Myocarditis
Cardiomyopathy
Pericarditis/ haemocarditis
Endocardosis/itis
Congenital HD
Base and myocardial tumours
Amyloidosis
Extracardiac causes of ventric arr
Same as for causes of arr in general discussed prev
Drugs/toxins causing ventric arr
DADADDEC
Digitalis
Anaesth
Doxorubicin
Atropine
Dobutamine
Dopamine
Epi
Chocolate…
Extra steps to be included in the new arr protocol if it suspected of being ventric
BP- however hyperT usually does not cause!
Inflamm markers: c- Tr-1: IC in myocytes, is heart specific and could indicate myocarditis!
CRP and SAA
Congenital Ventric arr
ARVC in BOXERS, bulldogs and cats
DCM: in dobermans and great danes
Ventric tachycard: german shepherds
ARVC in boxers
Autosomal dominant
All with the mutation are sick, but with different phenotypes because varying penetration
Signs when older than 6 although after no clinical signs (rxcept PCV)
Maye see extrasystoles in eCG
Syncope during stress/exercise
Maybe sudden death
Fibrous/fatty degen of the RV
ARVC in boxers- waht you must treat
The syncope- only if fainting due to the disease and not acc to another systemic illness eg insulinoma or SAS
Bradyarrhythmias=vasovagal syncope
the ventric tachycard: on an ECG can see up to 1000 VPC’s per day! pairs, triplets, tachycard, R on the T wave.
For this give Mexiletin or Sotalol (PO) or Atenolol
Diagnosis of ARVC in boxers *
Holter: Bradyarr and syncope!!
Bradyarr: after the syncope there are only a few VPCs because there is a compensatory incr in vagal activity after a symp surge! e.g when the dog is stressed/happy
This leads to vasoD… decr BP… dog faints
Try to avoid triggers and can tell the owner to elevate the HL’s when there is a fainting episode!
*eCG readings: the QRS complex is positive because the VPC is originating from the R ventricle
DCM in Dobermans
Holter for screening and treatment.
Should do US and eCG also
Often sudden death
Treatment of DCM in Dobermans
- HF and sinus ryhthm/ atrial fibrillation: diuretics and pimobendan. Beta blockers when no congestion and low dose digoxin
- HF and ventric arr: Mexiletine and Sotalol
- Syncope without HF: must screen with Holter to exclude bradyarr! beta blockers (sotalol) and Na channel blockers
- No clinical signs but VPCs on Holter: sotalol and pimobendan if the heart is enlarged
Supraventricular Extrasystoles
Causes:
- HD- atrial stretch and hypoxia
- Extracardiac
- Sometimes in healthy animals witha. high vagal tone
Checkand treat underlying cause ONLY!!
If symptoms: Digoxin, beta blockers, Ca channel blockers and Amiodarone
Supraventricular Extrasystoles appearance on eCG
Supraventric premature beats but usually cannot see origin
No preceeding P-wave
Junctional
Narrow QRS complex tachycradia
Narrow QRS always indicates SUPRAVENTRIC!! dogs<70ms cats<60ms
*wide QRS indiactes VENTRIC (sometimes supraventric)
Sinus tachycard
Supraventric tachycard:
- FAT: focal atrial tachycard
- Junctional tachycard
- OAVRT= bypass tachycard
- Atrial flutter
Atrial fibrillation
Sinus Tachycardia
- HR: fast but usually not above 200 bpm
- Rhythm:P–P distances and R—R distances only vary slightly (<10%)but have paroxysmal form i.e gradual acceleration and deceleration
- P waves: positive II or avF, there is a P for every QRS complex but it may be lost in prev ST segment or T wave. Could be higher in tachycard
- PQ distances: normal but could shorten when HR incr
- QRS complex: regular or abnormal if intraventricular conduction disorder
Causes of sinus tachycard
Mainly extracardiac e.g pain, fever, gastric dilation