arrhythmia 1 Flashcards
what abnormal anatomy can cause arrhythmias
LV hypertrophy
accessory pathways
congenital HD
what ANS can cause arrhythmias
sympathetic stimulation - stress, exercise, hyperthyroidism
inc vagal tone causing bradycardia
what metabolic can cause arrhythmias
hypoxia - chronic pulmonary disease and PE
ischemic myocardium - acute MI and angina
electrolyte imbalances
what else can cause arrhythmias
inflammation - myocarditis
what is an ectopic beat
beat or rhythm that originate in places other than the SAN
abnormal automaticity mechanism
SAN normally has overdrive suppression
in ischaemia, hypokalaemia or fibre stretch the automaticity of latent pacemakers may be inc and they can cause arrhythmias by escaping from SAN dominance
triggered automaticity mechanism
EAD occur in the purkinje fibres, induced by prolonged AP duration and inc inward current
DAD occur after repolarisation and are induced by inc Ca conc eg by catecholamines which inc Ca conc and HF which impairs Ca regulation
what is an example of an anatomic reentrant circuit
bundle of Kent - WPW
causes tachycardia as the bundle of Kent conducts faster
also structural abnormalities and scar from MI
what does inc phase 4 slope do
inc in HR and ectopics
- hyperthermia
- hypoxia
- hypercapnia
- cardiac dilation
- hypokalaemia
what does dec in phase 4 slope do
dec in HR and heart bock
- hyperkalaemia
- hypothermia
investigations
ECG
CXR
ECHO
stress or 24 hours ECG
what does exercise ECG assess for
ischaemia or exercise induced arrhythmia
what does 24hr ECG assess for
paroxysmal arrhythmia and to link symptoms to underlying heart rhythm
what does ECHO do
assess for structural heart disease
what are the symptoms of atrial ectopic beats
asymptomatic or palpitations
what is the treatment of atrial ectopic beats
none
avoid stimulants
SVT managent acute
inc vagal tone - vagotonic manoeuvres
slow AVN conductance - adenosine and verapamil
SVT maintenance
B blocker and verapamil
causes of AVN conduction disease - heart block
age
acute MI
myocarditis
drugs - B blockers and Ca channel blockers
calcific aortic valve disease
amyloid disease
what do you treat mobitz II with
permanent pacemaker
what is the use of Transcutaneous pacer
emergency temporary use till venous access achieved
what do most patients with VT have
heart disease - previous MI or coronary artery disease
treatment for ventricular fibrillation
defibrillation and cardiopulmonary resuscitation
treatment for VT
amiodarone or lidocaine
DC if unstable
how to treat a life threatening VT
ICD and CT catheter ablation
what are benign ventricular ectopics
Benign condition caused by extra-systoles and tends to have a benign course.
what is the classical presentation of benign ventricular ectopics
extra beat followed by a slight pause and then the heart beat returns to normal.
structurally normal heart and 24hr tape reveals ectopic beats