Arrhythmias Flashcards
Mechanisms of Arrhythmias:
1) Problems of impulse conduction
- AV block
- Reentry
2) problems of impulse formation
- automaticity
Requirements for reentry:
- birfurcated pathway
- different refractory periods between the two pathways
- unilateral slow conduction
MOA for reentry?
-signal begins but one branch is still hyperpolarized and cant send signal so entire signal goes down other branch and around and back to area that was hyperpolarized but is OK to depolarize now=the signal goes up and reenters where it started.
Abnormal automaticity generating arrhythmias?
-they do something
Premature beats:
- when occur?
- what happens as a result?
- Occur EARLY in the cycle
- prevent occurrence of next normal
- generate pause of varying length
Atrial Prematures
-features:
- premature
- abnormally shaped P-wave (may be small and difficult to see)
- normal QRS (could be aberrant-BBB)
- no compensatory pause (sometimes occurs)
**Most common cause of a pause on an ECG is…
nonconducted atrial premature - the earlier they happen the more likely the rest of the tissue hasnt repolarized = the signal is blocked
How to differentiate atrial and ventricular prematures?
Atrials will not have a compensatory pause while ventricular will.
which part of conducting system has longest refractory?
R bundle!
Junctional Prematures-
features
- arise in the AV junction –> can activate both the atria and ventricules
- P waves may be absent, before, or after QRS
What do junctional prematures look like?
-confused with ventricular prematures if QRS is wide
Ventricular prematures
-features:
- wide, bizarre QRS complexes
- no P-waves before QRS
- T-wave is frequently inverted
- ST segment slopes away from the QRS
- compensatory pause is usual
multiform means:
each one looks different - such as with Ventricular prematures
multiform diagnosis patients prone to:
V- fib
V-tach
Grade 0 ventricular premature descritpion: (Lown Classification)
NONE
Grade 1 ventricular premature depolarization (VPD) description (Lown Classification)
Less than 30/hr
Grade 2 VPD description: (Lown Classification)
30 or more/hr
Grade 3 VPD description: (Lown Classification)
multiform
Grade 4a/b VPD description: (Lown Classification)
- a=two consecutive CUPLETS
- b=three or more consecutive (v-tach)
Grade 5 VPD description: (Lown Classification)
R on T
What population gets Left ventricular prematures?
ASSOCIATED WITH HEART DISEASE
What population gets RIGHT ventricular prematures?
NORMAL PEOPLE
Left VPD on ECG:
- monophasic R or qR in V1
- qS or monophasic QS in V6
- “rabbit ear” in V1 (left peak)
