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Cardiovascular: arrythmias Flashcards

arrythmias

1
Q

what is the definition of a narrow complex tachycardia?

A

ECG >100bpm
QRS complex duration <120ms
which occur when ventricles are depolarised via the normal conduction pathways

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2
Q

what are the differentails for a narrow complex tachycardia?

A

regular narrow complex tachycardia

irregular narrow complex tachycardia which include:
1- normal variant- sinus arrythmia (rate changes with insp/exp), sinus rhythm with frequent ectopic beats

2- AF
3- Atrial flutter with variable block. Atrial rythmn regular, vent rhythm irreg

4- multifocal atrial tachycardia- p wave morphology and p-p intervals vary, associated with copd

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3
Q

how do you manage narrow complex tachycardia?

A

1- identify + treat underlying rhythm

2- if AVNRT or AVRT suspected transiently block AVN

3- some cases cause symptomatic episodes of sufficient severity + frequency to warrant more invasive treatment like ablation therapy for accessory pathways

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4
Q

how can you transiently block AVN in suspected AVNRT or AVRT?

A

1- vagal manoeuvres- carotid sinus massage, valsalva manoeuvre eg blowing into a syringe

2- IV adenosine

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5
Q

when the underlying rhthm is sinus tachycardia secondary to dehydration, how do you treat?

A

IV fluids

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6
Q

when the underlying rhthm is multifocal sinus tachycardia secondary to COPD, how do you treat?

A

correct hypoxia and hypercapnia

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7
Q

when the underlying rhthm is focal atrial tachyardia secondary to digoxin toxicity, how do you treat?

A

digoxin-specific antibody fragments

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8
Q

when the underlying rhthm is AVRT secondary to WPW, how do you treat?

A

flecainide or
propafenone or
amiodarone

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9
Q

what is holiday heart syndrome and which rythm disorders commonly present?

A

binge drinking in someone without any clinical evidence of heart disease can result in acute cardiac rythm and/or conduction disturbances

recreational marijuana has similar effects

SVT supraventricular tachyarrhthmia
AF (consider when new AF with no structural heart defect)

prognosis good- advise against excessive alcohol use

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10
Q

what is the normal conduction pathway?

A

SA node -> AV node -> Bundle of His -_ depolarises ventriuclar myocardium from bottom/apex to top/outflow tract

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11
Q

what is the pathway in sinus tachycardia?

A

conduction occurs as normal
impulses initiated at higher frequency

causes:

  • infection, pain, dehydration, bleed, systemic vasildation in sepsis
  • drugs- caffeine, nicotine, salbutamol
  • anaemia, fever, PE, co retention, autonomic neuropath y
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12
Q

what is the pathway in focal atrial tachycardia

A

group of atrial cells act as a pacemaker, out-pacing the SA node

p wave morphology is different to sinus

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13
Q

what is the pathway in atrial flutter?

A

electrical activity circles the atria 300x/min

gives sawtooth baseline

AV node passes some of these impulses on resulting in ventricular rates that are factors of 300- 150, 100, 75

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14
Q

what is the pathway in atrioventriuclar re-entry tachycardia AVRT?

A

an accessory pathway eg in WPW allows electrical activity from ventricles to pass to resting atrial myocytes, creating a circuit

atria- AVN- ventricles- accessory pathway- atria

orthodromic direction results in narrow QRS complexes as ventricular depolarisation is triggered via bundle of His- orthodromic conduction

antidromic direction results in broad QRS complexes

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15
Q

what is the pathway in AVNRT/atrioventricular nodal re-entry tachycardia?

A

circuits form within AVN
this causes narrow complex tachycardias
very common

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16
Q

what is the pathway in junctional tachycardia?

A

cells in AVN become pacemaker, giving narrow QRS complexes as imulses reach ventricles through normal routes

p waves may be inverted and late

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17
Q

what is the pathway in bundle branch block

A

any of the other conditions can result in broad copmlex tachyardias if there is a bundle branch block

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18
Q

what is the pathway in ventricular tachycardias VT?

A

this can result from circuits, similar to atrial flutter

or result from focuses of rapidly-firing cells

broad QRS
when circuit is in action and its plane rotates, ECG shows broad complex tachycardia with regularly increasing and decreasing amplitudes-_ torsades de pointes

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19
Q

in supraventricular arrythmias, the initial depolarisation originates from…?

A

atria or around AV node

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20
Q

in ventricular arythmies, the inital depolarisation originates from…?

A

ventricles

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21
Q

where is the accessory pathway in AVRT?

A

between the atria and ventricles

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22
Q

where is the accessory pathway in AVNRT?

A

between the atria and AV node

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23
Q

what is in the ECG to diagnose supraventricular tachycardias (AVRT/AVNRT)?

A

regular, narrow QRS complex tachycardia
rate 150-200
p waves abnormal

in WPW p wave is upside down and follows closely after QRS

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24
Q

what are the clinical features of supra ventricular tachyarrythmias?

A

recurrent attacks of rapid regular palpitations that last a few mins to hours/days (new onset post-MI suggests VT)

mild faintness- decreased JVP +/- low BP, varying intensity 1st Heart sound

unconscious- cardiogenic shock, very low BP

syncope if VT transient

sudden cardiac death

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25
what is the treatment for supraventricular tachyarrythmias?
aim is to slow conduction through AV node 1- vagotonic manoeuvres that increase vagal tone- valsalva manoeuvre, carotid sinus massage 2- drug IV adenosine, beta blockers 3- radiofrequency ablation
26
what is the accessory pathway involved in WPW?
an accessory pathway conducts atrial depolarisations directly into ventricular myocardium this bypasses AV node pre-exciation and AV reciprocating tachycardias and pre-excited AF may occur
27
untreated AF heart rate is usually...?
100-150bpm
28
what are the different classifications of AF?
paroxysmal persistent (medical cures) permanent (medical treatment doesn't keep them in sinus rhythm)
29
AF ECG diagnosis involves...?
QRS rate fast and irregularly irregular no p waves are visible baseline may be flat or show fast, small depolarisations
30
what are the clinical features of AF?
fast irregular palpitations- sudden onset, defined duration, sudden offset (if no underlying heart disease just this) breathlessness (impaired LV fx/HF) exercise capacity may be limited embolic events- stroke (late), limb ischaemia, mesenteric ischaemia syncope- rare- underlying sinus node disease
31
what are the cardiac causes of AF?
any structural heart disease- especially mitral stenosis | pericarditis
32
what are the metabolic causes of AF?
alcohol | thyrotoxicosis
33
what are the pulmonary causes of AF?
pneumonia PE COPD
34
what are the predisposing causes of VT (monomorphic)?
old/new MI LV hypertrophy HF cardiomyopathy
35
what are the causes of VT (polymorphic)?
genetic disease eg hereditary long QT syndrome- jervell-lange-nielsen syndrome, romano-ward syndrome (ion channel mutations) drugs that prolong QT interval (tricyclic antidepressants, amiodarone, quinidine, stall, antihsitamines ) acute myocardial ischaemia hypo- kalaemia, magnesaemia, calcaemia bradycardia- any cause
36
what is an idiopathic cuase of AF?
increasing age | more common in men than women
37
what is the treatment for AF (+ atrial flutter)?
1- rate control digoxin (slows rate at rest), Bb (slows rate at exercise), calcium channel antagonists 2- rhythm control amiodarone, flecainide, sotalol DC cardioversion if AF present for <1yr + heart normal otherwise ablation 3- anticoagulation CHA2DS2-VASC. Score 2 or more use warfarin INR target 2.5-3 or antithrombotic like dabigatran/rivaroxaban use HASBLED score to see risk of bleeding. 3 or more use with great caution. after cardio version CHADSCVASc score is high, stay on anticoagulant fro 2-3yrs becaues risk of recurrent AF is high
38
what is the ECG diagnosis for atrial flutter?
QRS rate is exactly 150 if alternate flutter waves conducted (atrial flutter with 2-1 block) or divisbles of flutter rate eg 100 (3 to 1), 75 (4 to 1) sawtooth flutter waves instead of p waves most obviously in leads II III aVF and VI *if regular tachycardia has constant rate of exactly 150 always think at. flutter even if flutter waves not obvious (can be obscured by QRS/T waves)
39
what are the clinical features of atrial flutter?
pulse rate usually 150 + regular asymptomatic or rapid palpitation breathlessness or be in HF
40
what is the pathogenesis of atrial flutter
atrial flutter is the result of a macro re-entry circuit moving anti-clockwise around R atrium atria depolaries in rapid coordinated fashion
41
what is seen on ECG for ventricular tachycardias?
QRS complexes broad wtih an abnormal shape VT always suspected when patient known to have heart disease (esp recent/remote MI) and regular tachy with broad QRS complex
42
what is the difference between monomorphic VT and polymorphic VT?
monomorphic VT- uniform QRS morphology, rate 120-190, maybe dissociated p waves as evidenc eof independent atrial activity polymorphic- less regular, more choatic, characteristic phasic variation in QRS morphology- torsades de pointes polymorphic VT is unstable and degenerates early on into VF
43
what are the clinical features of VT?
pulse rate fast, may be weak - no pulse palpable can be in acute HF, severely compromised, cardiac arrest (pulseless VT) or be well with rapid palpitation or breathlessness - still have a risk of haemodynamic deterioration
44
how do you treat pulseless VT or impending cardiovascular collapse?
DC cardio version - either immediately or after urgen anaesthesia/sedation
45
how do you treat haemodynamically stable VT?
IV lidocaine (lignocaine) or amiodarone never use multiple drug combos if drugs unsuccessful use DC cardioversion
46
how do you treat polymorphic VT?
DC cardioversion IV magnesium correction of underlying metabolic/electrophysiological abnormality slow heart reates prolong the QT interval and may worsen polymoprhic VT. so increasing HR by pacing often prevents or reduces incidenc eof polymorphic VT
47
how do you prevent future episodes of VT?
long term drug therapy- BB, amiodarone, ACEi, spironolactone to improve LV fx +maintain K+ revascularisation- CABG or PCI for severe coronary disease ICDs- implantable cardiovertor defibrillators- indicated for survivors of cardiac arrest and in symptomatic VT with impaired LV fx
48
if patients survive VF, it is important to find underlying cause. Full cardiac and coronary imaging takes place. what are some causes?
IHD- acute MI, critical coronary stenosis treated with complete revascularisation, no new ischaemia but old MI scar treat with ICD structural heart disease- cardiomyopathies- need ICD usually channelopathies eg hereditary long QT syndrome, Brugada's syndrome rare- WPW syndrome with complicating AF + very hihg HR; acquired long QT syndromes eg starvation
49
what are the ECG features for 1st degree AV block
prolonged PR interval
50
what is the site/cause of impaired conduction in 1st degree AV block
AV node | may be fucntional due to drugs or high vagal tone
51
what is the natural history/treatment for 1st degree AV block
if functional- progression unsuual if due to AV node disedase- progression common observation only
52
what are the ECG features of 2nd degree AV block Mobitz 1/wenckeback
some p waves not conducted progressive PR interval prolongation leads to dropped beat
53
what is the site/cause of impaired conduction for 2nd degree AV block Mobitz 1/wenckeback
AV node | may be functional due to drugs or high vagal tone
54
what is the natural history/treatment for 2nd degree AV block Mobitz 1/wenckeback
may be benign | but often needs pacemaker
55
what are the ECG features of 2nd AV block mobitz II?
only every 2nd or 3rd p wave is conducted
56
what is the site/cause of impaired conduction for 2nd degree mobitz II?
structural AV node/bundle of his disease
57
what is the natural history/treatment for 2nd degree heart blcok mobitz II?
always progresses to CHB 3rd degree early permanent pacemaker
58
what are the ECG features for 2rd degree CHB?
no p waves conducted p waves and ventricular escape rhythm completely indpendent- AV dissocation
59
what is teh site/cause of impaired conduction for 3rd degree CHB?
strucutral disease of AV node +/- conducting system
60
what is the natural history/treatment of 3rd degree CHB?
unreated death <6 weeks urgent pacemaker immediate pacemaker if history of syncope or HR <35

Medicine (3 decks)

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