Key notes Flashcards
HIS DEBS as arrythmogenic factors
H=Hypoxia—->COPD, PE
I=Ischemia and Irritability—->infarction, inflammation, infection
S=Sympathetic stimulation—->hyperthyroidism, CHF, nervousness, exercise
D=Drugs—->quinidine
E=Electrolyte disturbances—->Ca, Mg
B=Bradycardia—-> sick sinus syndrome
S=Stretch—-> enlargement and hypertrophy
Normal biphasic wave of P in which leads?
Lead III and V1
Normal septal Q wave in which leads?
Lead I, aVL, V5, V6 (rarely in inferior leads + V3, V4)
Normal QT interval over RR interval ratio?
40%
2 steps checking axis of QRS
1) Lead I and aVF (if both positive=normal range)
2) Lead with most equal biphasic QRS (perpendicular)
2 common causes for sustained ectopic rhythm
Digitalis toxicity, beta-agonists from inhaler therapies
4 Qs for arrhythmias
Q1: Are normal P wave present? including right axis
Q2: QRS wide or narrow? (3格界定)
* Q1 and Q2 decide the arrhythmia is ventricular or supraventricular (atrial or junctional).
Q3: What’s the relationship b/t P and QRS? (one-to-one=atrial origin)
Q4: Is the rhythm regular or irregular?
5 types of sustained supraventricular arrythmias
- PSVT=AVNRT (AV nodal reentranttachycardia)
- A flutter
- A fibrillation
- MAT (multifocal atrial tachycardia)
- PAT (paroxysmal atrial tachycardia)=ectopic atrial tachycardia
PSVT HR
150-250 bpm
3 leads to check the retrograde P wave in PSVT
Lead II, III, V1 (pseudo-R’)
Common causes of A fib
- Mitral valve disease
- CAD
- Hyperthyroidism
- PE
- Pericarditis
- Long-lasting HTN
2 irregular rhythm of supraventricular arrhythmia
A-fib, MAT
Define MAT (multifocal atrial tachycardia) and when is it commonly seen
> 3 different P wave morphologies
Severe lung disease
Pattern of PAT (paroxysmal atrial tachycardia). Can it be slowed down by carotid message as in PSVT?
a warm-up or cool-down period
No or mild slowing.
Rules of malignancies that PVCs may cause life-threatening arrhythmias
- Frequent PVCs
- > 3 PVCs in a row
- Multi form PVCs
- R-on-T phenomenon
- Any PVC occurring in the setting of an AMI
2 common conditions that accelerated idoventricular rhythm seen
- AMI
2. Early hours following reperfusion
How does Torsades de pointes occur?
A PVC falling during the elongated T wave
Electrolytes that cause TdP?
Hypo-Ca, hypo-Mg, hypo-K
ABX that cause TdP?
Erythromycin, quinolones, levofloxacin
Can supraventricular beat have a wide QRS?
Yes.
An early PAC occurs–> run through LBB (RBB still in refractory period)–> RBB receives conduction from LBB–> wide, bizarre QRS that looks like a PVC. (aberrant conduction)
Clinical clues to ddx VT and PSVT:
- Which is more common in a diseased heart?
- Which can be terminated by carotid massage?
- Which is commonly a/w AV dissociation?
- Cannon A wave may be seen?
- VT
- PSVT
- VT
- VT
What happen to AV node in AV dissociation?
Constantly refractory by impulses from above and below
EKG clues to ddx VT and PSVT:
- P always followed by QRS?
- Fusion beats may be seen?
- Initial deflection may in opposite direction of the normal QRS?
- PSVT
- VT
- VT
When does Ashman phenomenon occur?
It’s a wide, aberrant conduction of supraventricular beat after a QRS complex that is preceded by a long pause.
Bundle branches anticipate another long pause following this beat and repolarize slowly–> before completion of repolarization, another supraventricular impulse passes through AV node, but the conduction is blocked along the normal pathways–> wide, bizarre QRS (looks like a PVC)
