CVS: Arrhythmia

Question 1

Outline the pathophysiology of Arrhythmias

Answer 1

Disturbance of cardiac rhythm

Common, often benign, often intermittent

Question 2

Outline the Aetiology of Arrhythmias

Answer 2

Cardiac = MI, coronary artery disease, LV aneurysm, mitral valve disease, cardiomyopathy, pericarditis, myocarditis, aberrant conduction pathways

Caffeine

Smoking

Alcohol

Pneumonia

Drugs = beta 2 agonists, digoxin, L-dopa

Metabolic imbalance = K, Ca, Mg, hypoxia, hypercapnia, metabolic acidosis

Pheochromocytoma

Question 3

What are the signs and symptoms of arrhythmias

Answer 3

Asymptomatic

Palpitations

Chest pain

Presyncope/syncope

Hypotension

Pulmonary oedema

Question 4

How would you investigate an arrhythmia?

Answer 4

Bloods = FBC, U+Es, glucose, Ca, Mg, TSH

ECG

24h ECG monitoring

ECHO = any structural heart disease

Provocation tests = exercise ECG

Question 5

How would you manage SVT

Answer 5

Acute management = Valsalva/carotid massage, IV adenosine (blocks conduction through AV = remove QRS and only see atrial activity) or verapamil

DC (direct current) shock if compromised

Maintenance = beta blockers, verapamil

Question 6

How would you manage VF

Answer 6

Acute management = IV amiodarone, IV lidocaine, if no response DC shock

Amiodarone

Permanent pacing may be used to overdrive tachyarrhythmias, to treat bradyarrhythmia’s, or prophylactically in conductance disturbances

Question 7

What are the complications of arrhythmias

Answer 7

Formation of blood clots = stroke

Sudden cardiac arrest

Heart failure

Question 8

How would you manage bradycardia?

Answer 8

If asymptomatic and >40bpm = no treatment

Stop drugs that may be contributing = beta blockers, digoxin

If <40bpm and symptomatic = atropine, if no response insert pacing wire

Atropine = increases HR by reducing vagal stimulation

Question 9

How does bradycardia present on ECG?

Answer 9

Rate below 60bmp

Normal P wave with proceeding QRS

Question 10

How does atrial fibrillation present on ECG?

Answer 10

Irregularly irregular

Absent P waves (wavy baseline)

Rapid ventricular rhythm, (majority >100bpm)

Question 11

How does atrial flutter present on ECG?

Answer 11

Baseline - saw tooth appearance II, III, aVF

Question 12

How does VT present on ECG and how is it managed?

Answer 12

> 3 consecutive ventricular beats with a rate of 100-250bpm (100-120 = slow tachy, >250 = ventricular flutter)

Wide QRS complexes (> 3 small boxes)

More controlled appearance than VF

Mx =

• unstable = DC cardioversion
• stable = amiodarone

Question 13

How does a STEMI present on ECG?

Answer 13

(full thickness - endocardium to epicardium)

Acute = ST elevation

Late = ST elevation normalises, T wave inverts, Q wave deepens and persists

Question 14

How does a LBBB present on ECG?

Answer 14

Wide QRS (> 3 small boxes)

V1 - W, broad S wave

V6 - M

Question 15

How does a RBBB present on ECG?

Answer 15

Wide QRS (> 3 small boxes)

V1 - M

V6 - W

Question 16

How does 1st degree heart block present on ECG?

Answer 16

(slow conduction at AV node and bundle of His)

PR interval prolonged (>5 small squares)

Normal QRS

Question 17

How does 2nd degree heart block type 1 present on ECG?

Answer 17

Progressive lengthening of PR interval

Until 1 P wave is not transmitted

Question 18

How does 2nd degree heart block type 2 present on ECG?

Answer 18

PR interval normal

Sudden non-conduction of a beat = dropped QRS

Question 19

How does 3rd degree heart block present on ECG?

Answer 19

No relationship between P and QRS

Wide QRS

Rate is very slow = 30-40bpm

Question 20

How does a ventricular ectopic beat present on ECG?

Answer 20

Wide QRS complex

Question 21

What is the difference between SVT and VT?

Answer 21

SVT = improper electrical activity arising from the atria
- AVNRT = palpitations, SOB, chest pain, syncope

VT = improper electrical activity arising from the ventricles

Question 22

What are the indications for DC cardioversion?

Answer 22

Restore sinus when other treatments have failed

Haemodynamic compromise

SVT, AF, atrial flutter, VT

Question 23

What is wolff-parkinson-white syndrome?

Answer 23

Extra electrical pathway between the atria and ventricles (typically the left) = tachycardia

ECG = delta wave with narrow QRS

Question 24

How is AF managed?

Answer 24

Anticoag =

• structural heart disease = warfarin
• no heart disease = DOAC

Rate control = beta blocker (bisoprolol) or Ca channel blocker (verapamil)

Rhythm control =

• synchronised DC shock
• amiodarone, flecanide

Question 25

What scoring systems are helpful in determining whether a pt with AF should be taking long-term anticoag?

Answer 25

CHADSVASC (>2 offer anti-coag)

HAS-BLED

Question 26

What is a ‘Reveal’?

Answer 26

Chip inserted under the skin on the chest

Records ECG

Loops every 7 1/2 mins

Pt activates recording with controller

Lasts 3 years

Programmed to detect specific factors

Indications = syncope, dizziness, symptoms that aren’t frequent

Question 27

What is a pacemaker?

Answer 27

Indications = AF, sinus node dysfunction, AV block, after MI, prevent tachycardia

Lasts 6-15 years

Incision in vein, then insertion of of electrode lead into heart chamber/s

Guided by fluoroscopy

Function = if it doesn’t detect a normal beat-to-beat period it will stimulate the ventricle with a short low voltage pulse

Question 28

What causes AF?

Answer 28

Thyrotoxicosis

Previous IHD

Alcohol

Elderly

Question 29

How is atrial flutter managed?

Answer 29

1. rhythm control - cardioversion
2. rate control
3. ablation catheter = procedure used to remove or terminate a faulty electrical pathway
4. anti-coag
5. ECHO
6. Consider DC cardioversion