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Cardiovascular > Arrhythmias > Flashcards

Arrhythmias Flashcards

1
Q

What is an arrhythmia?

A

Abnormal heart beat

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2
Q

Where do SVT arrhythmias originate from?

A

Anywhere above the ventricle. SA node atrial muscle, His origin, AV node

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3
Q

Where do ventricular arrythmias originate from?

A

Ventricular muscle (common) or fascicles of the conducting system (uncommon)

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4
Q

Name some common Supraventricular arryhthmias?

A 
Tachycardias = Atrial fibrilation, atrial flutter, ectopic atrial tachycardia
Bradycardia = Sinus bradycardia or sinus pauses
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5
Q

What is a focus?

A

Origin of an arrythmia- any part of the heart that can fire and take over the normal rhythm

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6
Q

Name some common ventricular arrhythmias?

A

Ventricular ectopics or premature ventricular complexes (PVC)
Ventricular tachycardia or ventricular fibrilation (can lead to asystole)

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7
Q

Name some common AV nodal arrhythmias?

A 
AV nodal re-entry tahcycardia (AVNRT)
AV block (1st, 2nd or 3rd degree)
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8
Q

Abnormal anatomy is a cause of arrythmias. What aspects of anatomy can cause arrhythmias?

A

Left ventricular hypertrophy, accessory pathways or congenital heart defects

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9
Q

The autonomic nervous system is a cause of arrythmias. What aspects of the ANS can cause arrhythmias?

A 
Sympathetic stimulation (stress, caffeine, hyperthyroidism)
Increased vagal tone (bradycardia)
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10
Q

Metabolic conditions is a cause of arrythmias. What aspects of the metabolism can cause arrhythmias?

A

Hypoxia: chronic lung disease or PE
Ischemic heart diease: MI or angina
Electrolyte imbalance: K+, Ca++, Mg++

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11
Q

Which infections can cause arrhythmias?

A

Viral myocarditis

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12
Q

Which drugs can cause arrhythmias?

A

Direct electrophysiological agents or via the ANS

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13
Q

How can genetics cause arrhythmias?

A

Mutation of genes encoding for cardiac ion channels (Congenital long QT syndrome)

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14
Q

What is an ectopic beat and what can it leads to?

A

A beat or rhythm which originates outside of the SA node.

It can lead to altered automaticity or triggered activity

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15
Q

What is a re-entrant rhythm and and what are some common causes?

A

Rhythm generated outiside of the SA node which requires more than one conduction pathway with different speeds of conduction (depolarisation) and recovery of excitability (refractoriness)
Accessory pathway tachycardia (WPW syndrome)
Previous MI- scar tissue is inert
Congenital heart disease

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16
Q

How is a re-entry rhythm triggered?

A

By an ectopic beat resulting in a propagating circuit

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17
Q

What is automaticity and which part of the action potential does it usually effect?

A

The cells in the heart develop their own firing cycle and do not respond to the SA node. Can occur in the atria or the ventricles
Phase 4

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18
Q

Normally, why does automaticity come about?

A

Phase 4 (slow depolarisation) becomes faster due to:

1) Ion imbalance
2) Lowered threshold value
3) Increased resting potential

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19
Q

What can increase and decrease phase 4 conduction?

A

Increase: Hyperthermia, Hypoxia, Hypercapnia, Cardiac dilation, Hypokalemia
Decrease: Hypothermia or Hyperkapnia

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20
Q

What is triggered activity and which part of the action potential does it usually effect?

A

Where a small depolarisation, called an after depolarisation, occurs in the terminal phase of the action potential. If this is of sufficient magnitude to reach threshold it can lead to a sustained trail of depolarisation Phase 3

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21
Q

Give some common arrhythmias caused by triggered activity?

A

Torsades de pointes in long QT syndrome, digoxin toxicity

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22
Q

What is syncope?

A

A loss of consciousness due to a fall in BP

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23
Q

Give some common symptoms of arrhythmias?

A

Palpitations, SOB, Dizziness, Sudden Cardiac death, Angina and heart failure, Syncope or presyncope.
Can be assymptomatic and an incidental finding

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24
Q

What investigations are needed if you suspect and arrhythmia?

A 
12 lead ECG
CXR
Exercise ECG
24 hour ambulatory ECG
Event recorder- patient activated ECG
Echocardiogram
Eletrophysiological study- invasive but gives the opportunity to treat using radio frequency ablation
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25
What are you looking for on the ECG?
Pathological Q waves- signs of a previous MI Delta waves- signs of pre-excitation or accessory pathway. Slow rise in PR interval because of cell to cell transmission rather than a conduction pathway.
26
What condition has a typical delta wave?
Wolf Parkinson White syndrome due to the accessory pathway- bundle of Kent
27
What is sinus bradycardia?
Heart rate <60bpm
28
What is Sinus tachycardia?
Hear rate > 100bpm
29
What are the causes of sinus bradycardia?
Causes: physiological in atherletes. Drugs like beta blockers or ischemia in an inferior STEMI
30
What is the treatment for sinus bradycardia?
Treatment: Atropine if acute (antivagal and will speed up the heart. Pacemaker is haemodynamic compromise, hypotention, CCF or angina
31
What are the causes of sinus tachycardia?
Physiological- exercise, stress, anxiety. | Drugs
32
What is the treatment for sinus tachycardia?
Treat the underlying cause as arrhythmias are often a sign of other diseases Beta blockers
33
What is sinus arrhythmia?
Phasic variation in heart rate with respiration. Heart rate decreases during inspiration due to increased venous return
34
What is the treatment for sinus arrhythmia?
None | This is physiological and common in children and young adults
35
What are the symptoms of atrial ectopic beats?
Assymptomatic or palpitaions
36
What are the causes of atrial ectopic beats?
Usually benign but can be a sign of another disease like COPD
37
What is the treatment for atrial ectopic beats?
Often no treatment but aviod stimulants like caffeine and cigarettes. Beta blockers may help
38
What are the 3 causes of regular SVT?
AVNRT- AV nodal re-entrant tachycardia (re-entry within the AV node/micro re-entry) AVRT- AV re-entry tachycardia (re-entry via and accessory pathway/macro re-entry) EAT- Ectopic Atrial Tachycardia
39
How are regular SVTs treated?
Radiofrequency ablation to remove the slow pathway
40
Give and example of an irregular SVT?
Atrial tachycardia- AF and atrial flutter
41
What is the acute management of an SVT?
1) Increase the vagal tone. Valsalva manovre or carotid massage 2) Slow conduction in AV node. IV adenosine or IV Verapamil
42
What is the chronic management of SVT?
Aviod stimulants EP study and radiofrequency ablation (young fit and symptomatic) Beta blockers and anti arrythmic drugs
43
What is Adenosine, Atropine and Amiodarone used for?
``` Adenosine = slowing conduction in the AV node in SVT Atropine = increase conduction by suppressing vagal activity in sinus bradycardia Amiodarone = used in atrial and ventricular tachycardias ```
44
WHat is Radiofrequency Catheter Ablation (RFCA)?
Selective cautry of cardiac tissue to prevent tachycardia, targeting anautomatic focus or part of a re-entry circuit
45
What is necessary for RFCA?
Patient to be conscious throughout | Stop antiarrhythmic drugs to provoke the arrhythmia
46
What is the RFCA procedure?
1) ECG catheters placed into heart via femoral veins 2) Intracardiac ECG recored during sinus rhythm, tachycardia and pacing manovres to find location and mechanism of tachycardia 3) Catheter placed over focus/pathway and tip hearted to 55-65 degrees.
47
What are the causes of AV node conduction disease (heart block)?
``` Ageing Acute MI Myocarditis Drugs (beta blockers) Infiltrative disease (amyloid) Calcified aotric valve disease Post aortic valve surgery Genetic disease (Lenegne's disease, muscular dystrophy) ```
48
What genetic and infiltrative diseases can cause AV node conduction disease (heart block)?
``` Genetic disease (Lenegne's disease, muscular dystrophy) Infiltrative disease (amyloid) ```
49
What is first degree hear block?
Extended PR intervals (>0.2 seconds) due to increased AV nodal delay
50
What is the treatment fro first degree heart block?
No treatment required as it's usually assymptomatic but you can montor for development of more serious heart blocks
51
What is second degree heart block and what are the two types?
intermittent block at the AV node +> dropped ventricular beats Mobitz type 1 = progressive lengthening of the PR interval due to increased vagal tone Mobitz type 2 = Fixed block AV node conduction of 2:1 or 3:1
52
What is the treatment for second degree heart block?
Mobitz type 1 = No treatment just monitoring | Mobitz type 2 = Pathological and i may progress to 3rd degree heart block. Pacemaker required
53
What is third degree heart block?
Complete heart block. No action potential from the SA node pass through the AV node => Escape rhythm with broard QRS complex
54
What is the treatment for third degree heart block?
Needs a pacemaker
55
What are the two types of pacemaker (one for emergency use)?
Transcutaineous pacer: emergency use until venous access is achieved- painful for the patient Transvenous pacer: via internal jugular vein, subclavian vein or femoral vein.
56
What is the difference between a duel and single chamber pacemaker?
Duel chamber: two electrodes used to sense electrical current of the heart and deliver current to the heart. 1 elecrode to RA and one to apex of RV. Used for AV node disease as it maintains AV synchrony Single chamber: Just one electrode to the right atrium or right ventricle only
57
Give another name for ventricular ectopics?
Premature ventricular cmplexes
58
What is a premature ventricular complex (PVC)?
Premature beat arising from an ectopic focus in the ventricles => transient reduction in arterial pressure
59
What are some of the causes of premature ventricular complexes?
Structural: LV hypertrophy, Heart failure, Myocarditis Metabolic: Ischemic heart disease Marker of inherited cardiac conditions
60
What is the treatment for premature ventricular complexes?
Beta blockers of ablation of focus
61
What is Ventricular tachycardia (VT)?
Re-entrant circuit within the ventricles causing broad QRS complexes
62
What ate the two types of VT?
monomorhic VT: Where the circuit is going around a scar or one focus polymorphic VT: where there is more than one circuit/ multiple foci
63
What is haemodynamic instability?
An inability to perfuse organs represented by the clinical features of circulatory shock and severe heart failure
64
Are all patients with VT haemodynamically unstable?
No some may be alert
65
What are the causes of VT?
Significant heart disease: CAD and previous MIs | Rare causes: Cardiomyopathies, inherited/familial arrhythmia syndromes
66
What are some inherited/familial arrhythmia syndromes?
Long QT syndrome or Brugaola syndrome
67
What is Ventricular fibrillation?
Chaotic ventricular electrical activity which causes the heart to loose the ability to function as a pump
68
What is the acute treatment for ventricular fibrillation?
Defibrillation and CPR required
69
What is the acute treatment for VT in a patient who is haemodynamically unstable?
Direct current cardioversion (DCCV) | Given a general anasthetic and electrodes put on the chest
70
What is the acute treatment for VT in a patient who is haemodynamically stable?
Pharmocalogical cardioversion with antiarrythmic drugs (Amiodarone) while preparing for DCCV if necessary Look for the underlying cause
71
What is the long term treatment for VT?
1) Consider revascularisation for ischemia 2) Optimise CCF therapies 3) Antiarrhythmic drugs long term have been shown to be ineffective and lead to worse outcomes long term 4) Use an implantable cardiac defibrillator (ICD) if life threatening 5) Consider Radiofrequency ablation
72
Why is ICD not good if the patient is conscious and in VT and what is an alternative?
Very painful as it gives you a shock. | Use anti tachycardia pacing which is pain free
73
Until proven otherwise what is a wide QRS complex tachycardia with a cardiac history?
VT until proven otherwise
74
What causes most ventricular arrhythmias?
Structural heart disease: LV hypertrophy or heart failure
75
What is primary electrical disease?
VT/VF in structurally normal hearts. | Genetic cause and implications for family members
76
What are the defects of impulse formation?
Altered automaticity or triggered activity
77
What are the defects in impulse conduction?
Re-entrant rhythms (conduction block or accessory tracts)
78
What is physiological altered automaticity?
Modulation of the SA node activity by the ANS (eg sinus tachycardia, sinus arrhythmia)
79
What is pathological altered automaticity?
Another pacemaker in the heart overrides the SA node
80
When may pathological altered automaticty occur?
1) SA node firing frequency is pathologically low or when conduction from the AV node is impaired => escape beat or rhythm. 2) When another pacemaker fires at a faster rate than the SA node => Ectopic beat or rhythm
81
What is an escape beat?
Latent pacemaker initiates impulse (because the heart rate is pathologically slow)
82
What is ectopic beat?
Another pacemaker initiates an impulse
83
What are the common causes of ectopic beats?
Ischemia, hypokalemia, cardiac dialitaion or increase sympathetic activity
84
What is triggered activity?
After depolarisations triggered by a normal action potential
85
What are the 2 types of after depolarisation?
1) Early after depolarisation EAD | 2) Delayed afterpotential DAD
86
What is an EAD?
After depolarisation which occurs during the action potential in: 1) Phase 2 - mediated by Ca++ channels 2) Phase 3 - mediated by Na+ channels
87
What aspects of the ECG are associated with EAD?
Prolonged PR interval or prolonged QT interval
88
What is a DAD?
After depolarisation which occurs after complete repolarisation caused by a transient inward current involving Na+
89
What is associated with DADs?
Ca++ overload provoked by caterchol amines, digoxin and heart failure
90
What is a re-entry rhythm?
Self sustaining electrical circuit which stimulate the myocardium repeatedly
91
What is required for a re-entrant rhythm?
1) Unidirectional block where forwards conduction is prohibited but backwards conduction allowed OR 2) Variable conduction velocity/ length of refractory within two pathways
92
Action potentials which collide will extinguish each other. True or false?
True
93
What is the most common accessory tract pathway?
Bundle of Kent
94
Describable the 2 vagal manovres used in SVT?
Carotid massage Valsalvar manovre: blow out while holding your nose against a fixed volume and count to 10. These will both increase vagal tone
95
What drug can be used to prevent SVT passing into the ventricles?
IV bollus adrenaline 6mg (or varapamil)
96
What drug is given in severe sinus bradycardia?
Atropine (anticholinergic drug). | If this doesn't work give adrenaline or isoprenaline.
97
Treatment of Atrial flutter?
Amiodarone or DCCV
98
Treatment for AF within 48 hours of onset?
DCCV
99
Treatment for AF after 48 hours of onset?
Anticoagulate first as a clot may have formed in the heart and medical management to reduce hear rate- amiodarone/digoxin. After 6-8 weeks you can DCCV
100
Torsades des points is associated with hypokalemia. True or false?
True
101
Bundle brach block can lead to disynchroney of contraction of right and left ventricles. What is the treatment for this?
Cardiac resynchronisation therapy (CRT) either with a defibrilator or without

Cardiovascular (24 decks)

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