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Narrow complex tachycardias (supraventricular, SVT) (Clinical …
Narrow complex tachycardias
(supraventricular, SVT)
Clinical
presentation
Palpitations
Syncope
SOB
Chest pain
Diagnosis
Examination
Cardio exam
Tachycardia, may be pale,
sweaty, tachypnoeic
Investigations
Bloods
FBC (anaemia, infection), CRP (infection), U+E, LFTs,
clotting, glucose, lipids, troponins, amylase, D-dimer
Imaging
CXR (nil)
Bedside
Obs (high HR, high RR, fever if unwell)
ECG: sinus tachy; AVNRT has no p wave/short PR; AVRT has short PR, slurred start to QRS (delta wave) and narrow QRS
History
DH
Meds, allergies
FH
Cardiac disease, endocrine
PMH
Medical conditions, cardiac disease,
endocrine disease, anaemia
SH
Living arrangements, occupation,
leisure activities, smoking, alcohol, diet, drugs
PC/HPC
Chest pain (SOCRATES), palpitaitons,
SOB, syncope, recent acute illness
Management
Initial ABCDE
Definitive
Medical
Medical cardioversion
Indication: 2L stable patient
E.g. adenosine (1L), verapamil (2L),
sotolol (3L),flecainide, amiodarone
MOA: adenosine is AVN blocker, reducing ventricle rate
May need long term
DC cardioversion
Indication: 1L unstable patient; last resort stable patient
MOA: deliver electrical shock to restart heart rhythm
Vagal stimulation
Indication: 1L stabble patient
E.g. Valsalva manouvre, carotid sinus massage
MOA: stimulate AVN
Conservative
Information, advice, support
Admit if acutely unwell
Lifestyle (avoid aggrevators e.g. coffee, alcohol, exertion)
Surgical
Radiofreq ablation
Indication: AVRT e.g. WPW
MOA: destruction of accessory pathway
Definition
Irregularity of heart rhythm with
a narrow QRS thus pathology
arising above the ventricles
Epidemiology
Common
Usually transient due to
acute illness
Pathophysiology
Defect
Defect in atria or AVN
Causes a short circuit and fast
condution to the ventricles
Mechanism
Often no p wave as randomly generated elsewhere, but normal ventricular conduction so QRS is normal
Rare >100bpm
Types
AV junctional tachycardia
Two separate atrial conduction pathways
AVN re-entry tachycardia (AVNRT):
ring of conducting
pathways in the atria
AV reciprocating tachycardia (AVRT):
accessory pathway connects the atria to the ventricles e.g. WPW; prone to AF
Sinus tachycardia
Acute illness causing increased rate
stimulated by the SAN
Aetiology
AV junctional tachycardia
Congenital/genetic
Sinus tachycardia
Vascular: MI, PE
Infection: sepsis
Trauma: blood loss
Metabolic: fever, anaemia, hypovolemia
Drugs: atropine, catecholamines, amphetamines
Endocrine: thyrotoxicosis