Arrhythmias

Question 1

The 2 mechanisms of arrhythmias are

Answer 1

ectopic foci

reentry circuit

Question 2

Atrial flutter is

Answer 2

a re-entrant pathway in the atrium (usually right) causes supraventricular tachycardia

Question 3

Characteristics of atrial flutter on ECG

Answer 3

‘saw-tooth’ shaped “flutter waves” (F waves)

No P-waves

Question 4

Why is the ventricular rate of contraction slower than in the atria in?

Answer 4

due to the refractory period at the AVN

Question 5

Atrial fibrillation is

Answer 5

Multiple ectopic sites around the atria (usually overriding the SAN) cause the atria to quiver causing ventricular tachycardia

Question 6

Is the ventricular/pulse rate regular or irregular in atrial flutter

Answer 6

regular or irregularly irregular

Question 7

Is the venticular/pulse rate regular or irregular in atrial fibrillation

Answer 7

An irregularly irregular pulse, both in the rhythm and volume, is characteristic

Question 8

Atrial contraction rate is very high in atrial fibrillation but most of them don’t get through to the ventricles - why?

Answer 8

AVN refractory period

Question 9

Characteristics of atrial fibrillation on ECG

Answer 9

No P-waves
Irregular, narrow QRS
Baseline is flatter the more ectopic sites there are

Question 10

Ventricular tachycardia is

Answer 10

A rapidly firing ectopic foci or reentry circuit in the ventricle causes regular fast contractions (100-200bpm)

Question 11

Characteristics of ventricular tachycardia on ECG

Answer 11

wide, bizarre looking QRS
No P-wave
Can occur in short episodes of ~30secs (sustained needs immediate treatment or cardiac arrest)

Question 12

Heart rate in ventricular flutter

Answer 12

> 200bpm

Question 13

Whats the relationship between the atrial and ventricular contractions in ventricular tachycardia and flutter like?

Answer 13

complete dissociation as ventricular depolarisation not triggered by atrial site

Question 14

Ventricular fibrillation is

Answer 14

multiple weak ectopic sites in a ventricle giving unsynchronized chaotic signals causing the ventricles to quiver (fibrillate)

Question 15

Characteristics of ventricular fibrillation on ECG

Answer 15

No identifiable P-wave, QRS, or T-wave

Irregular waveforms of varying amplitude

Question 16

How does V-fib lead to death

Answer 16

Ventricles fibrillate, pump little/no blood, cardiac arrest

Question 17

Treatment of arrhythmia

Answer 17

Anti-arrhythmic drugs - Na/K/Ca channel blockers to try and get back to sinus rhythm
Beta blockers and Ca channel blockers- alters autonomic influence on heart to lower HR
Anticoagulants - stops clots forming in stagnant blood in heart (thrombus > stroke)

Question 18

Symptoms of ventricular tachycardia

Answer 18

SOB
Nausea
Dizziness
Chest pain

Question 19

What is a re-entry circuit?

Answer 19

A unidirectional block in a conducting pathway causing localised of global self-perpetuating electrical loop

(global as in “global re-entry” = re-entry circuit between atria and ventricles)

Question 20

most common AV block in atrial flutter is

Answer 20

2:1 AV block

Question 21

the most common arrhythmia is

Answer 21

atrial fibrillation

Question 22

Atrial bpm in atrial flutter

Answer 22

typically 250-320bpm

Question 23

Atrial bpm in atrial fibrilation

Answer 23

300-600bpm

Question 24

the main risk in atrial flutter and fib

Answer 24

embolic stroke - clots form in stagnant/slow moving blood

Question 25

what is direct current (DC) cardioversion

Answer 25

procedure where patients heart is defibrillated to get it back into normal rhythm (done under general anaesthetic)

(can give anti-arrhythmic drugs to do this pharmacologically)

Question 26

Atrial flutter and fibrillation can be assymptomatic and discovered incidentally or they can give the following symptoms

Answer 26

chest pain
palpitations
dyspnoea
faintness