Flashcards in EKG Quiz Deck (31)
What two leads should you consult to assess for RBBB or LBBB? How can you differentiate between the two?
look at V1 and V6
RBBB: V1 will have "rabbit ears"
LBBB: V6 will show abnormally wide QRS with a notched R wave
How can you assess for first degree heart block on an EKG?
PR interval >0.20 seconds and is constant from beat to beat
How can you assess for second degree AV block-Mobitz Type I on an EKG?
a progressive increase in the PR interval from beat to beat until finally the QRS complex, and a beat, is dropped.
What is another name for second degree AV block-Mobitz I?
How can you assess for second degree AV block-Mobitz II?
a sudden appearance of a nonconducted P wave; p waves are normal but some are not followed by QRS complexes; PR and RR intervals are constant.
Which is more serious.... Wenckebach or Mobitz Type II?
How can you assess for third degree heart block on an EKG?
independent (dissociated) atrial (P) and ventricular (QRS) activity; the P waves have no fixed relationship to the QRS complexes.
What is seen during inspiration with sinus arrhythmia?
an increase in HR
What is the reflex that is seen during sinus arrhythmia and what is occurring?
bainbridge reflex--> HR increases during inspiration b\c intrathoracic pressure falls.... so, IVC widens and venous blood pressure falls.... increasing venous return to the right atrium.... right atrium stretches and reflexively HR increases
How can you spot an atrial premature contraction?
The p wave is normally different than the sinus P waves and is conducted slightly earlier. Some may have a QRS follow, and some may not.
What happens if the p wave for an APC occurs too early?
it may fall on the T wave (when the ventricles are in the absolute refractory period) and thus be non-conducted.
What does subendocardial ischemia mean?
occurring beneath the endocardium or between endocardium and myocardium
What does transmural ischemia mean?
occurring across the entire wall
What is seen during subendocardial ischemia and injury in the ST segment?
depression of > 1 mm
What is seen in the ST segment during transmural ischemia and injury?
transmural ischemia: symmetrically inverted T waves
transmural injury: ST segment elevation > 1mm
Think about what is happening in the action potential of myocardial cells during contraction and the corresponding EKG tracing. Ventricular depolarization occurs from Q all the way until ventricular repolarization in the T wave. So in regards to calcium, what is seen on the EKG tracing with hypocalcemia and hypercalcemia?
hypocalcemia: prolonged QT segment
hypercalcemia: shortened QT segment
QT is normally around ~2 big boxes (0.4sec)
What does the QT interval represent?
the duration of the plateau phase (calcium)
What phase of the myocardial action potential represents ventricular depolarization?
phase 0 (Na influx)
What phase of the myocardial action potential represents ventricular repolarization?
phase 3 (K efflux)
What can be seen on an EKG in the presence of hyperkalemia?
peaked T waves (this is phase 3 when K+ efflux is occuring, so there is MORE K+ than usual= peaked T)
What can be seen on an EKG in the presence of hypokalemia?
U waves (not usually seen)
What HR is seen with paroxysmal atrial tachycardia (PAT)?
How do you treat PAT?
1) vagal maneuvers (carotid massage)
2) verapamil 5-10mg terminates AV nodal reentry (successful in ~90% of cases--> drug of choice)
3) esmolol 1mg/kg bolus and 50-200mcg/kg/min infusion shown effective in treating postop SVT's
4) propanolol in 0.5mg IV bolus doses
5) edrophonium (tensilon) in 5-10mg IV bolus doses
6) phenylephrine 100mcg bolus doses (if pt is hypotensive--> in effort to increase BP and achieve a reflex vagal slowing of HR)
7) IV digitalization with one of the short acting digitalis preparations: ouabain (0.25-0.5mg IV) or digoxin (0.5-1.0mg IV)
8) rapid overdrive pacing in effort to capture ectopic focus
9) cardioversion with appropriate synchronization
How do the P waves look with a PVC?
like nothing... there are none :)
What are the treatments for PVC's?
1st step: treat underlying abnormalities such as hypokalemia or low PaO2
2nd: lidocaine is usually the treatment of choice (initial bolus of 1.5mg/kg IV)
*recurrent PVCs can be treated with lidocaine infusion of 1-4mg/min
*additional therapy can include esmolol, propanolol, procainamide, quinidine, verapamil, disopyramide, atropine, or overdrive pacing
What two drugs should be avoided in WPW, and why?
digoxin and verapamil--> increases conduction through the accessory bypass tract (bundle of Kent) and decreases AV node conduction--> v-fib can occur
What is the hallmark EKG finding for WPW?
p waves normal; PR interval short (<100bpm
What are the best leads to detect posterior and inferior wall infarction? name the coronary artery that supplies it.
II, III, aVF--> right (RCA)
What are the best leads to detect septum and anterior wall infarction? name the coronary artery that supplies it.
V2-V5--> left anterior descending (LAD)