UCLA EKG MAIN EXAM TEST 2025/2026 QUESTIONS WITH
ANSWERS GRADED A+
✔✔ventricular pacemaker - ✔✔delayed LV activation, long spike down, maybe
retrograde P
✔✔sequential pacemaker - ✔✔2 spikes, one preceding a p wave and one preceding a
wide, bizarre QRS complex
✔✔what is the sudden, total occlusion that leads to infarction usually caused by? -
✔✔superimposed thrombosis initiated by rupture, erosion or fissuring of the
atherosclerotic plaque
✔✔3 stage evolution on EKG during acute MI - ✔✔1. T-wave peaking followed by T-
wave inversion
2. ST-segment elevation
3. Appearance of new Q waves
(any of these can be present without the others)
✔✔what happens to T waves w/ onset of infarction? - ✔✔T waves become tall and
narrow (PEAKING)
aka hyperacute T waves
a few hours later, the T waves invert
✔✔what do these T wave changes relfect? - ✔✔myocardial ischemia (lack of adequate
blood flow to myocardium)
✔✔is ischemia reversible? - ✔✔potentially: if blood flow is restored or O2 demands are
eased, T waves will revert to normal
✔✔how long will T wave inversion persist for after a true infarction? - ✔✔months to
years; not reversible
✔✔t wave inversion ALONE is indicative of? - ✔✔Ischemia; nonspecific finding, but T
waves of myocardial ischemia are inverted symmetrically
✔✔what does ST elevation signify? - ✔✔myocardial injury aka a degree of cellular
damage beyond that of mere ischemia
BUT IN MOST CASES THIS IS A RELIABLE SIGN THAT TRUE INFARCTION HAS
OCCURRED! ACT QUICKLY!!
✔✔Persistent ST-segment elevation indicates what? - ✔✔ventricular aneurysm
, ✔✔J point elevation - ✔✔in normal hearts. ST segment takes off from QRS complex
and looks like STE. ST segment returns to normal with exercise.
✔✔how id J point elevation different from an acute MI? - ✔✔with MI, elevated ST
segment is bowed upward and merges with the T wave. J point elevation = the T wave
remains a distinct, independent waveform
✔✔what does the appearance of Q waves mean? - ✔✔that irreversible myocardial cell
death has occurred. This is a diagnostic for MI
appear w/in several hours of onset of infarction. could take several days tho
pathological Q waves usually persist for the lifetime of the patient.
✔✔why do Q waves form? - ✔✔when a part of the heart dies, it can't conduct an
electrical current --> all of the electrical forces of the heart will be directed AWAY from
area of infarction, resulting in a deep negative deflection (a Q wave)
✔✔Reciprocal Changes - ✔✔opposing changes seen by distant leads due to an
increase in electrical forces moving towards them --> TALL POSITIVE R WAVES
applies to Q waves, ST segment and T wae changes
Lead distant from an infarct (STE) can show as ST depression
✔✔pathologic Q waves - ✔✔wider and deeper
Q wave > 0.04 s in duration
depth of Q wave must be at least 1/3rd of height of R wave in the same QRS complex
NOTE: do NOT use aVR to consider a patho Q wave for possible infarction. B/C aVR
normally has a very deep Q wave
✔✔what lead are large Q waves never "significant?" - ✔✔aVR
✔✔EKG changes of evolving MI - ✔✔1. acutely, T wave peaks and then inverts (reflects
ischemia)
2. ST segment elevates and merges with T wave. STE reflects myocardial injury. if
infarction occurs, ST segment returns to baseline w/in a few hours
3. new pathologic Q waves appear w/in hours to days which means you've had a MI.
can persist for life.
✔✔what artery supplies the AV node in MOST patients? - ✔✔right coronary artery
✔✔what does the LAD supply - ✔✔anterior wall of the heart and most of the IV septum
ANSWERS GRADED A+
✔✔ventricular pacemaker - ✔✔delayed LV activation, long spike down, maybe
retrograde P
✔✔sequential pacemaker - ✔✔2 spikes, one preceding a p wave and one preceding a
wide, bizarre QRS complex
✔✔what is the sudden, total occlusion that leads to infarction usually caused by? -
✔✔superimposed thrombosis initiated by rupture, erosion or fissuring of the
atherosclerotic plaque
✔✔3 stage evolution on EKG during acute MI - ✔✔1. T-wave peaking followed by T-
wave inversion
2. ST-segment elevation
3. Appearance of new Q waves
(any of these can be present without the others)
✔✔what happens to T waves w/ onset of infarction? - ✔✔T waves become tall and
narrow (PEAKING)
aka hyperacute T waves
a few hours later, the T waves invert
✔✔what do these T wave changes relfect? - ✔✔myocardial ischemia (lack of adequate
blood flow to myocardium)
✔✔is ischemia reversible? - ✔✔potentially: if blood flow is restored or O2 demands are
eased, T waves will revert to normal
✔✔how long will T wave inversion persist for after a true infarction? - ✔✔months to
years; not reversible
✔✔t wave inversion ALONE is indicative of? - ✔✔Ischemia; nonspecific finding, but T
waves of myocardial ischemia are inverted symmetrically
✔✔what does ST elevation signify? - ✔✔myocardial injury aka a degree of cellular
damage beyond that of mere ischemia
BUT IN MOST CASES THIS IS A RELIABLE SIGN THAT TRUE INFARCTION HAS
OCCURRED! ACT QUICKLY!!
✔✔Persistent ST-segment elevation indicates what? - ✔✔ventricular aneurysm
, ✔✔J point elevation - ✔✔in normal hearts. ST segment takes off from QRS complex
and looks like STE. ST segment returns to normal with exercise.
✔✔how id J point elevation different from an acute MI? - ✔✔with MI, elevated ST
segment is bowed upward and merges with the T wave. J point elevation = the T wave
remains a distinct, independent waveform
✔✔what does the appearance of Q waves mean? - ✔✔that irreversible myocardial cell
death has occurred. This is a diagnostic for MI
appear w/in several hours of onset of infarction. could take several days tho
pathological Q waves usually persist for the lifetime of the patient.
✔✔why do Q waves form? - ✔✔when a part of the heart dies, it can't conduct an
electrical current --> all of the electrical forces of the heart will be directed AWAY from
area of infarction, resulting in a deep negative deflection (a Q wave)
✔✔Reciprocal Changes - ✔✔opposing changes seen by distant leads due to an
increase in electrical forces moving towards them --> TALL POSITIVE R WAVES
applies to Q waves, ST segment and T wae changes
Lead distant from an infarct (STE) can show as ST depression
✔✔pathologic Q waves - ✔✔wider and deeper
Q wave > 0.04 s in duration
depth of Q wave must be at least 1/3rd of height of R wave in the same QRS complex
NOTE: do NOT use aVR to consider a patho Q wave for possible infarction. B/C aVR
normally has a very deep Q wave
✔✔what lead are large Q waves never "significant?" - ✔✔aVR
✔✔EKG changes of evolving MI - ✔✔1. acutely, T wave peaks and then inverts (reflects
ischemia)
2. ST segment elevates and merges with T wave. STE reflects myocardial injury. if
infarction occurs, ST segment returns to baseline w/in a few hours
3. new pathologic Q waves appear w/in hours to days which means you've had a MI.
can persist for life.
✔✔what artery supplies the AV node in MOST patients? - ✔✔right coronary artery
✔✔what does the LAD supply - ✔✔anterior wall of the heart and most of the IV septum
