Tachycardias (see DM for more depth)

Question 1

things to look out for when determining a tachycardia (9)

Answer 1

context; age; PMH; FH; congenital abnormalities; development of substrate; aquired abnormality; red flags (FH and present w cardiac arrest, syncope etc.); common presentations

Question 2

common tachy presentations (7)

Answer 2

asymptomatic; SOB; palpitations; pre-syncope; chest pain; collapse/LOC; cardiac arrest -always check what other associated symptoms there are e.g. sweating, nausea, sudden onset

Question 3

what happens to CO in tachys

Answer 3

decreases

Question 4

why does CO decrease in tachys

Answer 4

decreased time between contractions/incorrect contractions leads to less time for ventricular filling and therefore a decrease in the volume of blood pumped pumped out

Question 5

what counts as narrow complex tachycardia

Answer 5

> 100bpm, QRS <120ms (1.2 squares)

Question 6

what counts as broad complex tachycardia

Answer 6

> 100bpm, QRS >120ms

Question 7

irregular narrow complex tachy (what condition)

Answer 7

AF

Question 8

regular narrow complex tachy (5)

Answer 8

p waves - sinus tachy, focal atrial tachy
no typical p waves - atrial flutter, AVRT, AVNRT

Question 9

irregular broad complex tachy

Answer 9

pre-excited AF

Question 10

regular broad complex tachy (4)

Answer 10

p waves - atrially driven with aberration, pre-excited tachy;
independent p waves - VT
pacing spike - paced tachy

Question 11

where does AF usually arise from

Answer 11

focal pulmonary cells (i.e. where the pulmonary veins enter)

Question 12

atrial flutter ECG

Answer 12

“sawtooth” appearance of flutter waves (give adenosine to see more clearly) - inverted in inferior leads if anticlockwise reentry; Regular atrial activity at ~300 bpm; Loss of the isoelectric baseline; Ventricular rate depends on AV conduction ratio (usually 2:1 i.e. 150bpm)

Question 13

what is atrial flutter

Answer 13

regular tachy of 150bpm; caused by an ectopic beat which causes a “re-entrant
rhythm” in either atrium; usually anticlockwise re-entry (90%)

Question 14

common causes of atrial flutter (5)

Answer 14

RA dilation; ischaemic heart disease; idiopathic; normal variant; pt w history of endurance sport

Question 15

treatment of Atrial flutter

Answer 15

rate or rhythm control (same as AF); electrical cardioversion; radiofrequency ablation can be done if chronic

Question 16

what is a re-entrant circuit

Answer 16

in certain people the fibres in the conducting cells have different conduction speeds with different refractory times, if there are ectopic beats then these impulses may travel down the slow pathway while the fast pathway is refractory - when this impulse reaches the end of the slow pathway it then has the potential to go back up the fast pathway as it has now finished its refractory period (re-entry)

Question 17

what is wolff-parkinson-white syndrome

Answer 17

a syndrome that arises due to a congenital accessory pathway (bundle of kent) that causes early, slow, depol of the ventricles

Question 18

signs of narrow complex tachycardia (sinus, normal conduction)

Answer 18

abrupt rapid regular palpitations; presyncope

Question 19

wolff-parkinson-white ECG

Answer 19

pre-excitation, slurring of the upstroke of the P wave - delta wave; short PR interval (due to pre excitation); T wave abnormalities; dominant R waves in V1/V2; inferior q waves may be present

Question 20

what is AVNRT

Answer 20

a paroxysmal supraventricular tachycardia (ie it originates above the level of the Bundle of His) and is the commonest cause of palpitations in patients with hearts exhibiting no structurally abnormality; caused by abberant circuit within the AVN

Question 21

AVNRT ECG

Answer 21

tachycardia of 140-280 bpmwith normal and regular QRS complexes; No visible P-waves (hidden within the QRS complex)

Question 22

what is AVRT

Answer 22

paroxysmal supraventricular tachycardia that occurs in patients with accessory pathways, usually due to formation of a re-entry circuit between the AV node and accessory pathway; can be orthodronic or antidronic

Question 23

AVRT ECG

Answer 23

orthodromic: Rate usually 200-300 bpm, Retrograde P waves are usually visible, with a long RP interval, delta wave may be seen;
antidromic: Rate usually 200-300 bpm, Wide QRS complexes due to abnormal ventricular depolarisation via AP

Question 24

what is ventricular tachycardia

Answer 24

3 or more consecutive ventricular beats occurring at a rate greater than 120bpm; if > 30 seconds = sustained; can be monomorphic or polymorphic

Question 25

VT ECG

Answer 25

broad QRS complex; extreme axis; monomorphic – uniform QRS complexes in most leads (most common form); polymorphic – QRS of varying amplitudes, axis and duration across the leads

Question 26

difference between AVNRT and AVRT

Answer 26

with AVNRT tachy arises from near the AV node which similarly contracts the ventricle and the atria every time it goes around;

Question 27

what is torsades de pointe

Answer 27

specific form of PVT occurring in the context of QT prolongation — it has a characteristic morphology in which the QRS complexes “twist” around the isoelectric line; For TdP to be diagnosed, the patient must have evidence of both PVT and QT prolongation

Question 28

what arrhythmia is associated w digoxin toxicity

Answer 28

bidirectional VT; downward sloping T wave

Question 29

torsades de pointe ECG

Answer 29

Peaks of the QRS twist around the isoelectric line; Irregular RR intervals; Tachycardia with ventricular rates of 160 to 250 bpm; Prolonged QTc (male >0.43 s, female >0.45 s); R on T phenomenon; can trigger a run of polymorphic VT

Question 30

what is brugada syndrome

Answer 30

an autosomal sodium channelopathy associated with sudden cardiac
deaths; . Defective
sodium channels impair influx of sodium ions, resulting in shorter action potentials

Question 31

brugada syndrome ECG

Answer 31

brugada sign - downsloping coved ST elevation
followed by an inverted T wave - this is only present in leads V1 and V2;”

Question 32

what is ventricular fibrillation

Answer 32

A rapid, unco-ordinated and life-threatening ventricular arrhythmia resulting in poor
myocardial contraction, eventually leading to cardiac death

Question 33

VF ECG

Answer 33

Chaotic waveforms with varying amplitudes; Unidentifiable P-waves, QRS complexes or T waves

Question 34

what is long QT syndrome

Answer 34

prolonged ventricular repolarisation - can be congenital or acquired

Question 35

RBBB ECG

Answer 35

“MaRRoW” (M in V1, W in V6); Wide QRS complexes (>0.12 s); RSR’ pattern in V1
–V3 (M pattern); Long S wave duration in V6/1

Question 36

LBBB ECG

Answer 36

WiLLiaM (W in V1, M in V6); Wide QRS complexes (>0.12 s); Deep S wave in V1 and ‘M-shaped’ R wave in V6; Poor R wave progression in chest leads; ST elevation may be seen