EKG/ Arrhythmias Flashcards
QRS complex
ventricular depolarization
What does P wave represent
Atrial depolarization
PR interval; how many boxes is normal length
conduction delay through AV node
*less than 5 little boxes (under 200 msec; one little box is 0.04 s)
QT interval
mechanical contraction of ventricles
T wave
ventricular repolarization
*T wave inversion may indicate recent MI
Chaotic and irregularly irregular baseline with NO p-waves
Atrial fibrillation
Sawtooth pattern due to identical, back to back atrial depolarization waves
Atrial flutter
PR interval over 200 ms long; what two drug classes can cause?
1st degree heart block
*can be caused by Beta blockers and CCBs
Progressive lengthening of PR interval until a beat is dropped (p wave not followed by a QRS complex)
Mobitz type 1 2nd degree block (Wenkebach)
Dropped beat not preceded by a change in length of PR interval
Mobitz type II 2nd degree block
atria and ventricles beat independently of each other (p wave and QRS complexes have no resemblance to each other)
3rd degree (complete) heart block
*atrial rate is faster than ventricular
Delta waves (representing early ventricular depolarization)
Wolff-Parkinson-White syndrome (accessory signal that bypasses the AV node; also called ventricular pre-excitation syndrome)–> delta wave is caused by early ventricular depolarization, is where PR interval should be
Wide QRS after long pause; usually there is associated bradycardia; no p-wave
Ventricular Escape rhythm (failure of SA or AV node to originate a signal, eventually kind of just beat on their own due to intrinsic pacemaker activity)
Undulating amplitude of QRS may decompensate into v-fib
Torsades de pointe
wide QRS with tachycardia
Ventricular Tachycardia
Anything that prolongs the QT interval may predispose to what?
Torsades de pointe
What are 3 antibacterials that may prolong the QT interval?
Macrolides (esp erythromycin)
Chloroquine
Mefloquine
What two antipsychotics may prolong QT interval?
haloperidol and risperidone (other as well)
Which HIV drug class may prolong QT interval?
Protease inhibitors (-navir)
What two anti-arrythmic classes may cause QT prolongation?
1A –> quinidine
III –> sotolol, amiodarone
All together, what drugs prolong QT interval?
Macrolides (erythromycin), chloroquine and mefloquine
Haloperidol, risperidone
Protease inhibitors
Quinidine, amiodarone, sotalol
How does Ventricular fibrillation look on EKG?
Completely erratic rhythm with NO IDENTIFIABLE WAVES
*fatal without immediate CPR and defibrillation
Tx for acute Atrial fibrillation?
cardioversion
Tx for chronic A-fib?
Anticoagulation Rate control (digoxin, BB, CCBs) Rhythm control (sotalol, amiodarone)
*DONT CARDIOVERT TO NORMAL RHYTHM IF PRESENT OVER 48 HRS!! if clot has formed, normal rhythm may shake loose a clot that has formed–> stroke or PE will ensue
what does a narrow QRS indicate in general
that the signal is originating above the ventricles (SA or AV node)
AV node is pacemaker (narrow QRS), but slow rate
Junctional Escape Rhythm
early wide QRS with bizarre morphology, no p-waves
Premature Ventricular contractions (QRS is over 4 little boxes when normal is 1)
what causes PVCs?
microentry at the level of Purkinje fibers–> wide QRS tell you the signal is originating somewhere below the AV node
what can WPW lead to if not treated
Supraventricular tachycardia
ventricular bigeminy
PVC follows each sinus beat
ventricular trigeminy
2 sinus beats followed by a PVC
What does the height of the p-wave correlate with?
the K+ level–> too tall means hyperkalemia; flat p-wave can mean hypokalemia
what does the delay in the AV node allow for
ventricular filling
ST segment
represents the period in which the ventricles are depolarized; is isoelectric normally–> how long ventricles are deploarized
where is speed of conduction fastes?
purkinje fibers > atria > ventricles > AV node
tx for torsades
Mg sulfate
congenital long QT syndromes + severe congenital deafness
Jervell and Lange-Nielson syndrome–> due to defective cardiac Na or K channels
