ECG: SVT, bundle branch, AV blocks - Hefnawy Flashcards
1
Q
narrow and wide QRS in tachycardia
A
- anything above the bundle of HIS –> narrow QRS**
- anything below the bundle of HIS –> wide QRS**
2
Q
atrial tachycardia
A
- Ectopic foci can give you depolarization independent of SA node
- consistent P waves with single focal
- Variation in height/number of P waves with multifocal
3
Q
AVNRT
A
- signal going in circle in AV node and refiring atria
- depolarization wave going in opposite direction (bottom to top of atrium) –> inverted P wave due to vector
4
Q
AVRT
A
-Accessory bundle fibers traveling on other conductive fibers –> reentry tachycardia not involving the AV node
5
Q
sinus tachycardia vs. bradycardia
A
- tachycardia
- beats >100 bpm (high sympathetic tone) - bradycardia
- beats <60 bpm (high parasympathetic)
both have narrow QRS, normal PR intervals, equal RR intervals and height
- relying on sinus
- can see changes in respiration
6
Q
ectopic beats
A
- spontaneous beats from other parts of the heart that affect sinus rhythm
- single electrical beats outside the sinus node
7
Q
supraventricular tachycardia
A
- atrial ectopic beats
- atrial tachycardia
- junctional ectopics
- atrial fibrillation
- atrial flutter
8
Q
atrial ectopic beats
A
- depolarization triggered in atrium independent of sinus node –> premature P wave distorting the T wave
- sometimes missed beat bc AV node is in refractory period when atria depolarize again
9
Q
junctional atopics
A
- ectopic depolarization in at junction of atria and ventricles (typically AV node and surrounding area) –> inverted P wave (hidden by QRS) and narrow QRS
- may see absent P wave bc it happens early on
- inverted P wave due to depolarization of the atria in the opposite direction
3 variants: P wave can be hidden in the QRS, before, or after
-depolarization waves traveling to atria and ventricles at the same time in junctional
10
Q
atrial fibrillation
A
- ectopic depolarizations in all directions –> not measured on EKG bc of weak contractions –> lead to dilation of atrium
- usually at pulmonary veins entering LA –> treat with cauterization
- high risk of coagulation –> take anticoagulants
- no P wave –> fibrillation (f) waves instead (random, flat line)
- narrow QRS
- heart rate irregular
11
Q
atrial flutter
A
- ectopic depolarizations traveling in circle before entering other atrium
- HR more regular and predictive than Afib (larger F waves with more consistency)
- back to back F waves in leads V1-V3** –> sawtooth** bc not all depolarization can enter AV node
- look like P waves in leads V1-V3, sawtooth in inferior leads
- narrow QRS
- better outcome than Afib
- regularly irregular rhythm
12
Q
AVNRT (dual AV node) - SVT proper
A
- premature atrial P wave** –> stimulates slow path in AV node to bundle of HIS –> reaches bundle of HIS where fast track is now in refractory period stimulating it –> fires fast track back towards atrium to stimulate it again –> inverted P wave**
- treat with carotid massage (stimulates vagus nerve slowing down conduction) or Ca2+ channel blockers
13
Q
AVRT - SVT proper
A
- no AV node involvement
- triggered by premature beat
- Wolf-Parkinson White (bypass tract) –> accessory fibers that carry depolarizations straight to ventricles normally (seen as delta wave)
- orthodromic –> AV node working in right direction, but WPW working in opposite direction –> narrow QRS**
- antidromic –> WPW working in right direction, but AV node working in opposite direction –> wide QRS**
- retrograde P waves (if present) after QRS in both bc depolarization traveling in opposite direction
- retrograde P wave later than AVNRT
14
Q
ventricular tachycardia (VT) - 2 types
A
-more serious than SVT
- monomorphic VT
- most common type
- rapid firing of ectopic foci in ventricles
- QRS –> same shape, wide (longer time to depolarize), inverted (depol. in opposite direction), regular rhythm
- discordant T waves
- random P waves (not correlated with QRS) - polymorphic VT
- inconsistent QRS complexes
- caused by prolonged QT interval due to drugs
- Torsade de Pointes
- can lead to ventricular fibrillation and heart failure
15
Q
reentrant monomorphic VT
A
- paroxysmal –> not continuous
- rapid depolarizations –> inhibit other conduction paths
- slow rise in Na+/Ca2+ producing depolarization –> re-fire previous myocyte bc it is now in refractory period –> reentry
- depolarizations must spread cell to cell
