Ventricular arrhythmias Flashcards
3 types of vent arrythms
- V. Tachy
- monomorphic
- poly morphic - V. flutter
- V. fib
what is most important question to ask
does VT occur in setting of a normal heart
- organized VAs almost never caused by ischemia
4 things seen on ECG in monomorphic VT
- wide complex, originated from Vent
- 120-250bpm, at least 3 beats
- sustained = > 30 secs
- consitent beat-beat QRS morphology
2 main causes of VT
- reentry
- scarring
- His-purk disease
- idiopathic - automatic or triggered
- peri-infarction
- normal heart - catecholamine sensitive
3 methods to diff. VT from SVT w/aberancy
- HX
- PhX
- ECG
what are Hx predictors of VT
- age>40
- history of CAD, previous MI
- previous VT
2 Phx signs
- hemodyanamic stability
- not too helpful, because young ppl can stand it - AV dissociation
- cannon A waves in JVP
5 main ECG criteria to differentiate
- AV dissociation
- rate - not helpful
- QRS axis
- QRS duration
- QRS morpho
what does AV dissociation mean and 3 things to look for
diagnostic of VT
- fusion beats - part of one uses H/P system
- capture beats - one fully down H/P
- p -waves marching
what does axis tell you
high prob of VT if axis is right superior (+ in AVR)
what does QRS duration tell you
- > 140ms is 100 spec. for VT
- wider in myocardial disease, metabolic abnormal
- narrower with focus close to H/P system
what are 3 questions about QRS morphology
ANY yes = VT, all 3 NO = SVT
- absence of RS in all precorial leads
- onset R to nadir S > 100ms in any V lead
- morphology criteria in both V1-2 and V6
what are morphology criteria
LBBB like QRS V1or2 - R>30ms wide - >60ms to nadir of S - notched S V6 - QR or QS - monophasic R
Need both 1-2 and 6 to be met
3 points to remember
- in WCT, Vt is far more common than SVT
- if structrual heart diease present, PPV for Vt = 95
- can make correct diagnosis in most patients if apply criteria
what is poly morphic VT
not a nice repeating wave- need a code blue
- ischemia most common cause
- may be assoc. with long QT, but not always
- signature is usually sinus rythm and onset of poly VT with short couple PVC (
3 other important cause of poly VT
- bradycard
- hypokalemia
- hypomagnesia
what is long QT syndrome
- genetic defect in K channed
- prolonged repolarization
QT>450 in men
>460 in women
3 ECG signs of V flutter
- monomorphic
- rate>250
- usually hemo unstable and treated as fib
3 ECG signs of V fib
- polymorphic
- rate > 250
- can be very fine
Tx of VT
if unstable -shock
- do NOT give AV node blockade to PTs with WCT unless previous documented benefit or are sure this is not pre-ecxited Afib
5 ER scenarios
- mono VT with structural HD
- poly VT without long QT
- mono VT without structural HD
- poly VT with long QT
- vent. fib/flutter
what is and TX of xmono VT with structural HD
- related to reentryaround scar of old MI
- shock, amiodarone
- need to R/O ischemia as precipitant
what is and TX of poly VT without long QT
may be ischemia, lyte abnormal, catecholamine
TX
- amiodarone, IV Mg, shock
- then ischemia mgmt and eval
what is and TX of xmono VT without structural HD
- unlikely ischemia related
- most likely idiopathic benign
TX - very rare
- procainamide and or amiodarone
what is and TX of poly VT with long QT
- torsades de pointes
- may be secondary to drugs (many) or genetics
Tx - IV Mg
- correction of lytes
- removal of meds
- isoproterenol
Tx of flutter/lib
shock treat underlying cause - metabolic - drugs - ischemia
