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R-Cradio-illness > Arrhythmias Pathophysiology, Presentation and Investigation > Flashcards

Arrhythmias Pathophysiology, Presentation and Investigation Flashcards

1
Q

What is sinus rhythm?

A

Sinus rhythm is a normal heart beat, with respect to both the heart rate and rhythm
Normal heart rate is between 60 and 100 beats per minute

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2
Q

What is atrioventricular block influenced by?

A

Autonomic activity

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3
Q

What are the features of first degree atrioventricular block?

A

AV conduction is delayed, so PR interval is prolonged (> 20 secs)

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4
Q

What are the features of second degree atrioventricular block?

A

Dropped beats occur because some impulses from the atria fail to conduct to the ventricles

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5
Q

What are the features of Mobitz type I second degree AV block?

A

Progressive lengthening of successive PR intervals culminating in a dropped beat

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6
Q

What are the features of Mobitz type II second degree AV block?

A

PR interval remains constant but some P waves are not conducted

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7
Q

What are the features of third degree (complete) atrioventricular block?

A

AV conduction fails completely resulting in the atria and ventricles beating independently
Ventricular activity is maintained by an escape rhythm arising in the AV node or Bundle of His (narrow QRS complexes) or the distal Purkinje tissues (broad QRS complexes)

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8
Q

What is the pulse and SV in third degree AV block?

A

Slow pulse, 25-50bpm, large volume, that does not vary with exercise
Increased stroke volume

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9
Q

What murmurs can be heart in third degree AV block?

A

Systolic flow murmurs

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10
Q

What is the management of second and third degree atrioventricular block?

A

Second degree or complete may respond to atropine or temporary pacemaker

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11
Q

What is the management of second degree or complete heart block which is complicating an acute MI?

A

Requires a temporary pacemaker

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12
Q

What is the management of atrioventricular block with systole?

A

IV atropine or isoprenaline to maintain circulation until pacemaker is inserted

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13
Q

What is the management of chronic atrioventricular block?

A

Permanent pacemaker

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14
Q

What is atrial flutter characterised by?

A

Large re-entry circuit within the right atrium, usually encircling the tricuspid annulus

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15
Q

What is the atrial rate in atrial flutter?

A

Approximately 300/min

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16
Q

What is atrial flutter usually associated with?

A

Atrioventricular block

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17
Q

When should atrial flutter be suspected?

A

Where there is a narrow complex tachycardia of 150/min

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18
Q

How might carotid sinus massage or IV adenosine help establish a diagnosis of atrial flutter?

A

By temporarily increasing the degree of AV block and revealing the flutter waves

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19
Q

What is the most common sustained cardiac arrhythmia?

A

Atrial fibrillation

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20
Q

What is atrial fibrillation characterised by?

A

The presence of multiple, interacting re-entry circuits looping around the atria

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21
Q

What are episodes of atrial fibrillation initiated by?

A

Salvoes of ectopic beats that can arise from conducting tissue in the pulmonary veins or from diseased atrial tissue

22
Q

What is the pulse in atrial fibrillation?

A

Irregularly irregular

23
Q

What is the ECG like in atrial fibrillation?

A

Irregular QRS complexes with no P waves

24
Q

What are the types of atrial fibrillation?

A

Paroxysmal
Persistent
Permanent

25
Q

When is atrial fibrillation more likely to become sustained?

A

In enlarged atria with slow conduction

26
Q

What is the presentation of atrial fibrillation?

A

Palpitations
Dyspnoea
Fatigue
May precipitate or aggravate cardiac failure
Light-headedness if hypotension
Chest pain if underlying coronary disease
Often asymptomatic and detected accidentally

27
Q

What is the management of atrial fibrillation?

A 
Full history and examination 
12 lead ECG - document arrhythmia 
Echocardiogram 
Thyroid function
Exercise tolerance test
Treat any underlying primary disorder e.g. if complicating an acute illness
Beta blockers
CCBs for rate control
Anticoagulation if stroke/emboli risk
28
Q

What is supraventricular tachycardia?

A

Supraventricular tachycardia is used to describe a range of regular tachycardias that have a similar appearance on an ECG
These tachycardias are usually associated with a narrow QRS complex and are characterised by a re-entry circuit or automatic focus involving the atria

29
Q

What are the features of AV nodal re-entrant tachycardia?

A 
Palpitations
Dyspnoea
Dizziness
Good prognosis
No treatment 
Narrow QRS complex
30
Q

What is the management of supraventricular tachycardia?

A

CCBs e.g. verapamil/diltiazem for paroxysmal SVT

CCBS and beta-blockers e.g. atenolol, bisoprolol for frequent or disabling SVT

31
Q

Describe Wolff-Parkison-White Syndrome

A

In Wolff-Parkinson-White syndrome there is a strip of accessory conducting tissue that allows electricity to bypass the AV node and spread from the atria to the ventricles rapidly and without the delay
When the ventricles are depolarised through the AV node, the ECG is normal, but when the ventricles are depolarised through the accessory conducting tissue the ECG shows a very short PR interval and a broad QRS complex

32
Q

When is ventricular tachycardia most commonly seen?

A

In patients with CHD or cardiomyopathies

33
Q

Why is ventricular tachycardia serious in patients with CHD or cardiomyopathies?

A

It can lead to haemodynamic compromise or ventricular fibrillation

34
Q

What is the presentation of ventricular tachycardia?

A 
Palpitations
Chest pain
Dyspnoea
Dizziness
Syncope
35
Q

What is the management of ventricular tachycardia?

A

Fast sodium channel blockers e.g. quinidine
Intermediate sodium channel blockers e.g. phenytoin
Slow sodium channel blockers (only in severe dysrhythmias) e.g. flecainide
Beta blockers e.g. atenolol for myocardial depression
Amiodarone, sotalol or bretylium if sustained/life threatening

Implantable cardioverter defibrillator

36
Q

What is the presentation and management of ventricular fibrillation?

A

Presents with collapse and sudden cardiac arrest

Cardiac arrest protocol to be followed

37
Q

What is sinus tachycardia?

A

Defined as a sinus rate of more than 100/min and is usually due to an increase in sympathetic activity associated with exercise, emotion, pregnancy or pathology

38
Q

In what people can a rapid sinus rate be normal?

A

In young adults with intense exercise

39
Q

In what people can a sinus rate of less than 60/min be normal?

A

In healthy people at rest e.g. in athletes

40
Q

What are some pathological causes of sinus bradycardia?

A 
MI
Sinus node disease
Hypothermia
Hypothyroidism 
Drugs
41
Q

What is the treatment of sinus bradycardia?

A

No treatment if asymptomatic

Symptomatic usually responds to IV atropine

42
Q

What is sinus arrest?

A

A condition wherein the sinoatrial node of the heart transiently ceases to generate the electrical impulses that normally stimulate the myocardial tissues to contract and thus the heart to beat

43
Q

What is the presentation of atrial ectopic beats?

A

Usually asymptomatic but can give the sensation of a missed or abnormally strong beat

44
Q

What does the ECG show in atrial ectopic beats?

A

Shows premature but otherwise normal QRS complex

If visible, the preceding P wave has a different morphology because the atria activate from an abnormal site

45
Q

What might atrial ectopic beats precede, if occurring frequently?

A

Onset of atrial fibrillation

46
Q

What does the ECG show in ventricular ectopic beats?

A

QRS complexes are of abnormal morphology because the bundle branches are activated one after the other, rather than simultaneously
The ECG shows premature broad complexes which may be unifocal or multifocal

47
Q

What effect do ventricular ectopic beats have on the stroke volume?

A

Ectopic beats produce a low stroke volume because left ventricular contraction occurs before filling is complete

48
Q

What is the pulse in ventricular ectopic beats?

A

Pulse is irregular, with weak or missed beats, or abnormally strong beats

49
Q

What does the significance of ventricular ectopic beats depend on?

A

Presence or absence of underlying heart disease

50
Q

What are the indications for ICD therapy?

A

Secondary prevention
Cardiac arrest due to VF/VT not due to transient or reversible cause e.g. early phase of acute MI
Sustained VT causing syncope or significant compromise
Sustained VT with poor LV function

51
Q

What are the indications for temporary pacing?

A

Intermittent or sustained symptomatic bradycardia, particularly syncope
Prophylactic when a patient is at high risk for development of severe bradycardia e.g. 2nd or 3rd degree AV block, post-anterior MI, even when asymptomatic

52
Q

What are the indications for permanent pacing?

A

Symptomatic or profound 2nd/3rd degree AV block, particularly when cause is unlikely to disappear
Probably Mobitz type II 2nd and 3rd degree AV block, even if asymptomatic
AV block associated with neuromuscular diseases
After, or in preparation for, AV node ablation
Alternating right bundle branch block/left bundle branch block
Syncope when bifascicular/trifascicular block and no other explanation
Sinus node disease associated with symptoms
Carotid sinus hypersensitivity/malignant vasovagal syncope

R-Cradio-illness (27 decks)

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