Electrophysiology Flashcards
The SA node is supplied by which arteries?
In 55% of ppl, the RCA.
In 45% of ppl, the LCA.
The AV node is supplied by which artery?
The SA nodal artery.
It arises from:
In 90% of ppl, the RCA.
In 10% of ppl, the LAD.
The RBB and LASF bundle are supplied by which artery?
In 50% of ppl, the LAD.
In 50% of ppl, the AV nodal artery and the LAD.
The LPIF is supplied by what arteries?
Will LAD infarction affect the LPIF?
In 50% of ppl, the AV nodal artery, and 50% the AV nodal artery and LAD.
LAD infarction will usually cause block of the RBB and LASF, but very rarely will it affect the LPIF.
How should you break down tachycardias?
What is meant by SVT?
Classically, what are the two rhytms that are classified as an SVT?
A tachycardia originating above the AV node.
AvnRT and AVRT.
What percentage of people with SVT have AvnRT vs AVRT?
60% have AvnRT (AV re-entry)
20% have AVRT (bypass tract re-entry)
20% have SVT that re-enters at orther sites
What are characteristics of AvnRT?
Rate: 180-250 bpm in both atria and ventricles
Small R’ wave, and QRS <120msec
How is AvnRT treated?
Vagal manouevers: Valsalva (must be held for at least 10 seconds, 20-25% success), carotid massage, ice on face (used only for children)
Adenosine (6mg): (90% success rate, safe in unstable, safe in pregnancy, and in narrow complex WPW)
Sync. Cardioversion:
CCBs and Beta Blockers: 2nd line. Have hypotensive effects.
What are the characteristics of AVRT?
Most are anterograde thru the AV, and re-enterant through the bypass tract.
85% of WPW are ORTHOdromic in nature (narrow complex)
ANTIdromic (wide complex) is hard to differentiate from VT, and should be treated as such in the ED.
What defines WPW type A?
WPW type B?
Type A: Positive delta wave in V1, with dominant R wave
Type B: Negative delta wave in V1, with dominant S wave
A small portion of WPW may have a bypass circuit that has a quicker refractory time than the AV node.
If this person developed a Afib or AF, excessive stimulation of the ventricles may occur.
ANTIdromic WPW with Afib or AF (a venticular rate >300 on monitor) should be watched for what?
And what should be avoided in their treatment?
Precipitation into VF.
Avoid Beta blockers, CCBs, and adenosine, as it may block the AV node, which favors the 1:1 conduction through the fast bypass circuit, and will further increase the chances of potentiating a VF or VT.
Treatment should be synced cardioversion or procainamide (this does block the bypass circuit)
What gives you L axis deviation?
LVH
Inferior MI
LAFB
What gives you R axis deviation?
RVH
LPFB
Dextrocardia
Mixing up of electrodes
Lung hyperinflation (heart rotates more vertical)
What causes early R wave progression?
RVH (uniform progression)
Posterior MI (2 contig leads)
RBBB
WPW
HOCM
Peds ECG
