Arrhythmias Flashcards
1
Q
Sinus arrhythmia
A
- P for every QRS but R-R varies
- All PQRS complexes look the same–rate is just what is varying
- SA node rate varies w/ respiration
- HR increases w/ inspiration, decreases w/ exhalation
- Vagal tone–fit, brachycephalic, chronic bronchitis
- Eye/abdominal surgery
- Atropine
- No treatment required
- Not normal in cats–only dogs
2
Q
Wandering atrial pacemaker
A
- P waves from outside SA node
- Variable morphology/amplitude of P wave
- Usually goes in nice wave pattern (+, -, +, etc.)
- Variable P-R interval
- Increased vagal tone usually
- No hemodynamic consequences–no treatment
3
Q
Sinus bradycardia
A
- Rate
- Outside the heart–drugs, lytes, thyroid, vagal tone–eye/gut, respiratory, lesions, idiopathic (atropine test)
- Atropine test: kills vagal tone–> HR goes up
- Drugs: digoxin (causes any arrhythmia), xylazine, beta blockers, lidocaine
- Inside the heart–fibrosis, infect, trauma, neoplasia, idio
- Signs if > 6-8 s
- Exercise animal to make sure HR goes up (could just have a normally slow HR)
4
Q
Treatment for sinus bradycardia?
A
- Remove the cause
- Correct the drug dose/use
- Lower the K
- Treat the hypothyroid
- Atropine or glycopyrrolate test
- = look for vagal problems
- Terbutaline/isoproterenol/isopropamide/ probanthine
- Need to counteract PNS–can’t block it so increase SNS instead
- = look for vagal problems
- = pacemaker if clinical
5
Q
Pacemaker
A
- Pulse generator
- Pacing leads endo/epicardial
- Transvenous (through jugular vein–> bottom of right heart)
- Epicardial
- Transdiaphragmatic
- Demand; exercise
- Infection; scarring; twitching; arrhythmias; effusion
- Cannot re-use human pacemakers
6
Q
Sinus arrest
A
- Failure of SA node–1/more beats
- Drugs/lytes/vagal tone, etc. as before
- > 6 s = signs
- Atropine test, check lytes; treat as you would for sinus arrhythmia
7
Q
Junctional (nodal)/ventricular escape beats
A
- Keeps circulation going to brain (keeping animal alive) when the sinus beat fails to materialize
- Normal QRS but no P wave = junctional
- Abnormal QRS + no P wave = ventricular
- Junctional escape will occur first, then ventricular (often if junctional doesn’t work)
8
Q
Which monitor can be used to record junctional/ventricular escape beats?
A
- Holter/cardiac event monitor–continuous recording, only remembers last 30-60 sec; hit button to record last minute to permanent memory
9
Q
What is the treatment of junctional/ventricular escape beats?
A
Positive chronotropes/pacemaker
10
Q
Hyperkalemia
A
- Renal failure; ATE; hyperadrenocorticism; crush
- Raises resting membrane potential–> heart fibrillates
- Bradycardia
- T waves tall
- P waves disappear
- Prolonged QRS
- Sinusoidal shape
- Bicarb/glucose, Ca glutonate for treatment
- Give fluids that don’t contain K
- Boluses of glu better than insulin–glu raises insulin levels
- Bicarb works if underlying cause is acidemia
- Ca effusion to lower resting membrane potential
11
Q
AV block
A
- Delay or failure of transmission at the AV node
- Outside heart–drugs, lytes, thyroid, vagus
- Inside–ischemia, -itis, neo, trauma, genes, idio
12
Q
1st degree AV block
A
- PR > 0.13s/0.09s
- Usually drugs or vagal tone
- No treatment–monitor
13
Q
2nd degree AV block–Mobitz type I
A
- Intermittent failure of conduction
- Mobitz type I
- PR interval increases until QRS dropped–Wenkebach
- Vagal tone/drugs
- P wave consistent = sinus perfectly fine
- QRS not responding consistently = intermittent AV block
- Can hear clinically–watch chest to differentiate from sinus arrhythmia
14
Q
2nd degree AV block–Mobitz type II
A
- No PR changes before dropped QRS
- Node disease
- Ratio– P : QRS
15
Q
2nd degree AV block–high grade node disease
A
- Can’t tell if it’s Mobitz type I or II
- Only 1 normal beat before dropped beat
- High grades more likely to develop into type III down the road (= BAD) –> poor prognosis
16
Q
3rd degree AV block
A
- No AV conduction
- P waves and escape beats
- AV/junctional (40-60 bpm)
- Ventricular < 40 – bizarre-looking
- Completely independent of each other
- Give atropine test, check lytes
- Usually ends up being disease of AV node
- Damaged–> replaced by fibrous tissue
17
Q
What is the treatment for AV block?
A
- Treat the cause–stop dig, treat itis
- If symptomatic try drugs if responsive to atropine test
- Emergency isoproterenol/dopamine IV (if responsive to atropine)
- If not atropine responsive:
- Pacemaker–inc. survival over 6 months
- Need for grade III
- Pacemaker–inc. survival over 6 months
- Won’t always show clinical signs (ex: old dogs who don’t exercise)
- Pay attention to dogs with low heart rates during physical exams–normally nervous/excited
18
Q
Sick sinus syndrome
A
- Abnormal sinus node and AV system
- Sinus bradycardia
- Intermittent sinus arrest/AV block
- Paroxysms of tachycardia
- Intermittent weakness/syncope
- Send home w/ monitor
- Drugs??–ventricular demand pacemaker
- Can’t use drugs to treat both–one will make the other worse
- Pacemaker to treat sinus arrest, then drugs to control tachycardia
19
Q
Sinus tachycardia
A
- Increased HR– > 160-180bpm/240bpm
-
Normal P QRST
- No arrhythmia, HR just too fast
- Physiological–fear, pain
- Pathological–fever, anemia, thyroid
- Anemia–heart beat is stronger–heart must pump fewer # of RBCs harder/faster to effectively reach tissues; “waterhandle” pulses
- Common in cats with hyperthyroidism
20
Q
SPD’s and sinus tachycardia
A
- Premature
- Part of the atrium depolarizes spontaneously–> can become pacemaker–> premature depolarization
- Variable P
- May be buried in T wave
- Normal QRS
- Lab/boxer–8y–66% heart disease
- Cardiomyopathy
- Neoplasia
- Re-entry
21
Q
Diagnosis?
A
Supraventricular premature depolarization
23
Q
Ventricular premature depolarizations (contractions)
A
- Ectopic focus–ventricle
- Hypertrophy, inflammation, trauma, hypoxia, drugs, systemic conditions, anesth., etc.
-
QRS–premature + no P wave
- Wide and bizarre
- Junctional escape beats–premature = occurs after very short beat
24
Q
Triplets and fusion beats–what do they look like?
A
- Mix of P wave and ectopic focus
- Might look like multiple lesions–>look for P wave to ensure fusion beat
25
Q
What is this an example of?
A
Bigeminy
26
Q
What is this?
A
Doublets
27
Q
What are the VPD signs?
A
- Dropped heart sounds
- Irregular pulse
- Dropped pulses
- Rarely–weakness/syncope
- Commoner–sudden death
- Not no’s
- Runs R-on-T
31
Q
Ventricular tachycardia
A
- Serious–maybe pre-fibrillatory–same causes as VPD
- Runs at > 3VPDs at > 160-180 bpm
- Sustained > 30s
- Non-sustained–dec. ectopic focus firing/capture beats
- Signs: 300 bpm for > 6-8s (heart fx)
32
Q
Treatment for VT?
A
- Treatment as for VPDs
- Won’t stop all VPDs or all deaths
33
Q
Accelerated idioventricular rhythm/idioventricular tachycardia
A
- Spontaneous ventricular depolarizations at 60-180bpm
- Capture and fusion beats
- Asymptomatic mostly
34
Q
Treatment for accelerated idioventricular rhythm/tachycardia?
A
- Correct underlying electrolyte/acid base imbalances or systemic conditions
- Monitor–VT may be coming
35
Q
Ventricular fibrillation
A
- Usually terminal
- Irregular and disorganized ventricular activity
- No CO/coronary flow
- Coarse or fine
- Arises from ectopic foci/reentry/’R on T’
37
Q
Atrial fibrillation
A
- Common–DCM + lone AF
- Chaotic activity
- Multiple ectopic foci
- No P waves
- Normal QRS
- R-R random
- No “atrial push”
- Tachycardia–Inc. myocardial O2 demand but dec. CO and dec. cardiac perfusion (coronary flow down 60%)
41
Q
Differential diagnoses for atrial fibrillation?
A
- 60 Hz interference
- Atrial flutter
