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Cardiovascular System > Arrhythmias Pathophysiology, Presentation and Investigation > Flashcards

Arrhythmias Pathophysiology, Presentation and Investigation Flashcards

(52 cards)

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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?

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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?

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A

Irregularly irregular

23
Q

What is the ECG like in atrial fibrillation?

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A

Irregular QRS complexes with no P waves

24
Q

What are the types of atrial fibrillation?

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A

Paroxysmal
Persistent
Permanent

25
When is atrial fibrillation more likely to become sustained?
In enlarged atria with slow conduction
26
What is the presentation of atrial fibrillation?
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
What is the management of atrial fibrillation?
``` 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
What is supraventricular tachycardia?
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
What are the features of AV nodal re-entrant tachycardia?
``` Palpitations Dyspnoea Dizziness Good prognosis No treatment Narrow QRS complex ```
30
What is the management of supraventricular tachycardia?
CCBs e.g. verapamil/diltiazem for paroxysmal SVT CCBS and beta-blockers e.g. atenolol, bisoprolol for frequent or disabling SVT
31
Describe Wolff-Parkison-White Syndrome
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
When is ventricular tachycardia most commonly seen?
In patients with CHD or cardiomyopathies
33
Why is ventricular tachycardia serious in patients with CHD or cardiomyopathies?
It can lead to haemodynamic compromise or ventricular fibrillation
34
What is the presentation of ventricular tachycardia?
``` Palpitations Chest pain Dyspnoea Dizziness Syncope ```
35
What is the management of ventricular tachycardia?
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
What is the presentation and management of ventricular fibrillation?
Presents with collapse and sudden cardiac arrest | Cardiac arrest protocol to be followed
37
What is sinus tachycardia?
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
In what people can a rapid sinus rate be normal?
In young adults with intense exercise
39
In what people can a sinus rate of less than 60/min be normal?
In healthy people at rest e.g. in athletes
40
What are some pathological causes of sinus bradycardia?
``` MI Sinus node disease Hypothermia Hypothyroidism Drugs ```
41
What is the treatment of sinus bradycardia?
No treatment if asymptomatic | Symptomatic usually responds to IV atropine
42
What is sinus arrest?
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
What is the presentation of atrial ectopic beats?
Usually asymptomatic but can give the sensation of a missed or abnormally strong beat
44
What does the ECG show in atrial ectopic beats?
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
What might atrial ectopic beats precede, if occurring frequently?
Onset of atrial fibrillation
46
What does the ECG show in ventricular ectopic beats?
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
What effect do ventricular ectopic beats have on the stroke volume?
Ectopic beats produce a low stroke volume because left ventricular contraction occurs before filling is complete
48
What is the pulse in ventricular ectopic beats?
Pulse is irregular, with weak or missed beats, or abnormally strong beats
49
What does the significance of ventricular ectopic beats depend on?
Presence or absence of underlying heart disease
50
What are the indications for ICD therapy?
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
What are the indications for temporary pacing?
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
What are the indications for permanent pacing?
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

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