SVT Flashcards
how to interpret ECG ?
is it regular or irregular
are there p waves present
is the QRS complex wide or narrow
what is the rate
what are the causes of SVT
cardiac - heart failure , myocardial infarction , cardiomyopathy
respiratory - PE , COPD
infections
metabolic causes - such as thyroid problems
electrolyte imbalances - such as hypo or hyperkalemia , hypo magnesia
alcohol and drugs - caffeine and amphetamines
pain and stress
investigations that you would order for SVT ?
bedside - ECG , ABG!! msu/csu
BLOODS - FBC UE ELECTROLYES - POTASSIUM MAGNESIUM , BONE PROFILE, THYROID FUNCTION , COAGULATION SCREEN , D-DIMER , TROPONIN
CXR - cardiomegaly , infection , heart failure
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echo - to look for any structure pathology
24 hr ecg
medications for SVT
MOST TACYCARDIA RESOLVES BY RESOLVING THE UNDERLYING PROBLEM - ANTIBIOTICS FOR INFECTION , replacing electrolytes , ACS protocol
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before medication and because they are hemodynamically stable
i would do a carotid massage and valsalva manurer
if this does not work i would escalate it to y medical registrars to start them on adenosine 6mg
and wait ten minutes
and then load with 12mg
then given another 18mg
OR verapamil (FOR ASTHMATICS)
how does adenosine work ?
blocks the av node - leaving a temporary block
contraindication of adenosine ?
asthma
heart block
decompensated heart failure
QT syndrome
Before giving adenosine you should explain to the patient
may experience flushing, nausea, light-headedness associated with a ‘sense of impending doom’. This is secondary to TRANSIENT asystole
by giving adenosine if patent converted to normal rhythm what does this imply ?
tachycardia can be considered NODAL in origin (if it is atrial in origin, adenosine will only transiently block it. It can self terminate but often reverts back
if tachycardia resumes how do we treat it ?
Beta Blockers (1st Use cautiously in patients with signs of pulmonary disease or heart failure) or CCBs (2nd line e.g. diltiazem)
radio frequency ablation
if you are unsure of the rhythm / vtach what medication will you give ?
amiodarone - AFTER DISCUSSION WITH A SENIOR
if patient becomes unstable
synchronised dc SHOCK UP TO 3 TIMES
AMIODARONE 300MG in 20 mins
repeat synchronised shock
and then amiodarone 900mg in 24hrs
Different types of SVT ?
SVTs can be classified based on:
Site of origin (atria or AV node) or;
Regularity (regular or irregular)
Regular Atrial:
Sinus tachycardia
Atrial tachycardia
Atrial flutter
!!!! Sinus node reentrant tachycardia !!!!
Irregular Atrial
irregular atrial
Atrial fibrillation
Atrial flutter (variable block)
Multifocal atrial tachycardia
atrioventricular
AVRT (Atrioventricular reciprocating tachycardia (AVRT)
AVNRT!!!!
atrioventricular nodal re-entry tachycardia (AVNRT) = most common
ECG features increasing the likelihood of VT instead of SVT with aberrancy
more to VT
Absence of typical RBBB or LBBB morphology
Extreme axis deviation (“northwest axis”): QRS positive in aVR and negative in I and aVF
Very broad complexes > 160ms
AV dissociation:
P and QRS complexes at different rates
P waves are often superimposed on QRS complexes and may be difficult to discern
Capture beats: Occur when the sinoatrial node transiently “captures” the ventricles in the midst of AV dissociation, producing a QRS complex of normal duration
Fusion beats: Occur when a sinus and ventricular beat coincide to produce a hybrid complex (see Dressler beat)d
