arrhythmia Flashcards
what can arrhythmias cause
- sudden death
- syncope
- heart failure
- chest pain
- dizziness
- palpitations
what are 2 main types of arrhythmias
- bradycardia. (<60bpm)
- tachycardia(>100 bpm)
what are tachycardia subdivided into
- SVT
- ventricular
what leads to tachycardia
- reduction of parasympathetic tone
or
- increase in sympathetic tone
what produces bradycardia
- increased parasympathetic
or
- decreased sympathetic
who has faster sinus rate men or women
women
what is normal sinus rhythm characterised by on ECG
p waves upright in leads I and II
why is sinus bradycardia in athletes
due to their increased vagal tone
extrinsic causes of bradycardia
- hypothermia
- drug therapy e.g. beta blocker
- raised intracranial pressure
intrinsic causes of bradycardia
- infarction of sinus node
- fibrosis
what. does chronic symptomatic sick sinus require
permanent pacing
how many forms of atrioventricular block is there
3
what is first degree AV block
prolongation of PR interval
what are 2 forms of second degree AV block
Mobitz I
Mobitz II
what is Mobitz I
progressive PR interval prolongation until p wave fails
what is Mobitz II
every nth p wave is dropped
when is pacing indicated
in Mobitz II
what may an acute MI produce
second degree heart block
what is third degree AV block
complete heart block
what infection can cause AV block
- endocarditis
- lyme disease
- chagas disease
what does narrow complex escape rhythm imply
that it originates in the His Bundle
what does the left bundle subdivide into
anterior and posterior divisions of left bundle
what is complete bundle branch block do to QRS
widen it up to >0.12 secs
right bundle branch block produces
late activation of the right ventricle
what is seen in ECG of right bundle branch block
deep S wave in leadsI and V6
tall late R wave in V1
looks like an M (MaRRoW)
what does left bundle branch block look like on ECG
deep S wave in lead V1
tall R wave in leads I and V6
W shape (MaRRoW)
what is bifsacicular block
is a combination of a block of any two of the following:
right bundle branch
left antero-superior division
left posterior-inferior division
symptoms of right bundle branch block
splitting of second heart sound
what does right branch block occur
- isolated congenital anomaly
- atrial or ventricular septal defect
- pulmonary stenosis
- Fallots tetraology
- pulmonary embolism
- pulmonary hypertension
- MI
- fibrosis
causes of left bundle branch block
- aortic stenosis
- hypertension
- MI
- coronary disease
where do SVT arise from
the atrium or atrioventricular junction
what is conduction via in SVT
His-Purkinje system
sinus tachycardia ECG
similar to sinus rhythm
atrioventricular nodal re-entrant tachycardia ECG
no visible p wave
atrioventricular re-entrant tachycardia ECG
p wave visible between QRS and T
atrial fibrillation ECG
irregularly irregular RR
atrial flutter ECG
waves at 300. bpm
sawtooth appearance
2:1 AV conduction
multifocal atrial tachycardia ECG.
multiple p wave morphologies
irregular RR intervals
what is sinus tachycardia a sign of
cardiac stress - physiological or pathological
acute causes of sinus tachycardia
- exercise
- emotion
- pain
- fever
- infection
- acute heart failure
- acute pulmonary embolism
- hypokalaemia
chronic causes of sinus tachycardia
- pregnancy
- anaemia
- hyperthyroidism
- catecholamine excess
what should be used to slow the sinus rate in hyperthyroidism
beta blockers
who is atrioventricular nodal re-entrant tachycardia more common in n
women
where are accessory pathways most commonly situated
on the left
what is most common accessory pathway known as
Kent bundles
are accessory pathways that conduct form the ventricles to the atria visible on ECG
no they are concealed
what is a pre excited ECG characterised by
short PR interval
wide QRS
what have patients with a history of palpitation and pre-excited ECG have
Wolff-Parkinson-White syndrome
during atrial fibrillation what can the ventricles be depolarised by
impulses travelling over both abnormal and normal pathways
what drugs can precipitate ventricular fibrillation
verapamil
digoxin
what drugs should not be used to treat WPW syndrome
verapamil
digoxin
symptoms of SVT
- palpitations (abrupt onset and sudden termination)
- anxiety
- dizziness
- dyspnoea
- neck pulsation
- central chest pain
- weakness
- polyuria
how can SVT palpitations be terminated
valsalva manouevres
what can irregular palpitations be due to
atrial premature beat
atrial flutter
atrial fibrillation
multi-focal atrial tachycardia
what can happen in patients with uncontrolled atrial fibrillation
cardiac output can reduce and cause hypotension and congestion heart failure
why may polyuria occur in SVT
because of release of atrial natriuretic peptide in response to increased atrial pressure
why does prominent jugular venous pulsation occur during SVT
due to atrial contracts against closed AV valves
treatment of SVT in patient who is haemodynamcially unstable
emergency cardioversion
treatment of SVT in stable patient
vagal manoeuvres
e.g. right carotid massage, face in cold water
how should valsalva manoeuvre be done
patient is resting in supine position
what is does next if physical manoeuvres are not successful in SVT
intravenous adenosine
what is adenosine
naturally occurring purine nucleoside
it causes complete heart block for a fraction of a second
what is half life like in adenosine
very short
what are side effects of adenosine
- bronchospasm
- flushing
- chest pain
- heaviness in limb
- sense of impending doom
when is adenosine contraindicated
people with asthma
as it can induce atrial fibrillation
what is alternative treatment for adenosine
verapamil or beta blockers
what is long term management of. SVT
referred to cardiologist
ablation of an accessory pathway
examples of sodium channel blockers
flecainide
where do atrial tachyarrhythmias arise
atrial myocardium
what are atrial tachyarrhythmias caused by
- increasing age
- MI
- hypertension
- obesity
- diabetes mellitus
- myocarditis
- pericarditis
- surgery
- electrolyte imbalance
- alcohol
- chest infection
- hyperthyroidism
