These flashcards will help prepare you for Dr. Esterson's EKG exam on the internal medicine clerkship.

1 small box = __ seconds

.04 s

1 large box = __ seconds

.20 s

__ small boxes = 1 large box

5 small boxes

What is the amplitude of each small box?

1 mm or .1 mV

The normal height of EKG standardization is __ mV or __ mm.

1 mV
10 mm

What formula can be used to calculate heart rate given the R-R interval? (assume regular rhythm)

300 / # large boxes in R-R interval
1500 / # small boxes in R-R interval

If there are 3 large boxes in the R-R interval, the heart rate = __ . (assume regular rhythm)

100 bpm

How do you determine HR given an irregular rhythm?

Measure out 6 seconds (6 second rule). Count the # of complexes in 6 sec and multiply by 10.

List 3 criteria for normal sinus rhythm.

1) Rate between 60-100
2) Every normal P wave followed by QRS
3) P wave upright in leads I and II, inverted in aVR.

Length of normal PR interval =

.12 - .20 s (3 to 5 small boxes)

Define PR interval

from ONSET of P wave to ONSET of QRS

Length of normal QRS =

<0.10 s

Define QRS interval

from ONSET of QRS to END of QRS

Define QT interval

from ONSET of QRS to END of T wave = systole

List the FRONTAL leads

I, II, III, aVR, aVL, aVF

List the HORIZONTAL leads


Lead I runs from the __ to the __.

Right arm to left arm.

Lead II runs from the __ to the __.

Right arm to the left leg.

Lead III runs from the __ to the __.

Left arm to the left leg.

State where the positive lead is in lead I.

Left arm

State where the positive lead is in lead II.

Left leg

State where the positive lead is in lead III.

Left leg

____ leads record potentials between one extremity and the sum of the other two.


List three unipolar leads.

aVR, aVL, aVF

State where the lead is in aVR.

Right shoulder

State where the lead is in aVL.

Left shoulder

State where the lead is in aVF.

Left foot

Which lead is at 0 degrees?


Which lead is at 30 degrees?


Which lead is at 60 degrees?


Which lead is at 90 degrees?


Which lead is at 120 degrees?


Which lead is at -30 degrees?


Which lead is at -150 degrees?


What part of the heart do leads V1-2 "see" best?

atrial, septal leads

What part of the heart do leads V2-4 "see" best?

anterior LV leads

What part of the heart do leads V5-6 "see" best?

lateral LV, precordial leads

What is the normal range of the axis of the heart?

-30 to +90

Related to age <30, normal heart range = __

0 to +90 (even +105)

As we age, the heart axis changes to __

-30 to +90

Overweight people have an axis that is shifted __.


A "Left Axis" heart is from __ to __

-30 to -90

A "Right Axis" heart is from __ to __

+90 to 180

An "Extreme Axis" heart is from __ to __

+180 to -90

Which three leads do you check to determine axis?

I, II, aVF

Describe the QRS axes for a "normal" heart.

+ in I and II, either in aVF

Describe the QRS axes for a "left" heart.

+ in I, - in II, - in aVF

Describe the QRS axes for a "right" heart.

- in I, either in II, + in aVF

Define "normal" P wave morphology.

I and II positive; aVR negative

Which leads are best to see P wave?

II and V1

Transition Zone: There is a progression of precordial R waves. Before V2, they should be (+/-) and (+/-) by V5.

Negative before V2
Positive at V5

The ST segment is defined from the __ to the __.

J point to the beginning of the T wave.

List 2 EKG findings that can progress to infarction.

- ST depression
- symmetric T wave inversion

A positive EKG stress test will show __.

ST depression > 1 mm

What does the EKG show in the HYPERACTURE period following an MI?

Tall T wave

What does the EKG show in the injury/acute period in the few hours following an MI?

ST elevation with tall T (tombstone)

In the later stages following an MI, an EKG will show what changes?

Pathological Q waves. T returns upright and ST becomes normal.

Which coronary artery feeds the inferior and posterior wall of the LV, and the RV?

Right coronary

Which coronary artery feeds the IV septum and anterior wall of the LV?


Which coronary artery feeds the lateral wall of the LV?


LVH should show ___ voltage.

Increased left voltage, due to increased mass

Which segment represents systole?


The corrected QTc should be ___ s

< .44 s

An ST elevation with a concave upwards slope suggests...

Early repolarization

Describe the common case of early repolarization

A usually healthy male>female, athlete, with no symptoms

What is the difference between an ST elevation in MI and pericarditis?

STEMIs are more regional whereas pericarditis is seen in all leads except aVR and isoelectric leads

Describe the criteria for RBBB

- QRS elongation, >.12s
- R' in right precordial leads (V1)... R' is wider and taller than R wave
- Wide S in lateral leads
- Secondary ST-T changes (opposite direction)

Describe the criteria for LBBB

- QRS elongation, >.12s
- absent Q waves in lateral leads (I, V5-6)
- broad R wave (I, V5-6)
- Secondary ST-T changes (opposite direction)
- LAD common

Describe the criteria for LVH

- !!Increased QRS voltage
- ST-T "strain" changes in left sided leads
- Slight QRS elongation
- Abnormal Left axis deviation

An R in Lead I > 15 mm = __

An R>S in V1 = __



What is the usual axis of RVH?

>110 degrees

What EKG findings are associated with HYPERKALEMIA?

- peaked T waves
- QRS prolongation (widenen T)
- P waves with long duration, low amplitude
- Increased PR interval
- P wave disappears
- QRS sine wave

What is characteristic about the A fib EKG?

- No definite P shape can be determined
- Irregularly irregular P waves at 400-700 bpm
- Normal QRS at 100-180 bpm

What is characteristic about the A flutter EKG?

- Saw tooth shape
- Normal QRS

What is characteristic about PVCs: Premature Ventricular Complexes?

- Wider and different from sinus QRS
- Not preceded by premature P wave
- Significance depends on the clinical setting

Define Ventricular tachycardia

- 3 or more PVCs
- abrupt onset and termination
- rate 140 - 200
- QRS >.14
- not preceded by P waves

Describe Type I Second Degree AV Block

- Progressively lengthening PR interval, then a non-conducted P

Describe Type II Second Degree AV Block

- PR interval is constant, followed by a non-conducted P
- bi/trifascicular block

Describe Third Degree AV Block

- Regular PP and RR intervals, VARIABLE PR INTERVAL!
- Atrial rate > ventricular rate

"25 y.o. senior medical student presents to the ER the night before Match Day, complaining of sharp chest pain and tenderness."

Normal EKG

"45 y.o supervisor with chest tightness and arm heaviness after foot surgery."

Subendocardial ischemia / ischemic ST depression

What is necessary about Q waves to show necrosis?

There must be Q waves in 2 separate leads

"75 y.o. Miami physician retired to N Dakota. He presents with chest pain while shoveling snow."

Ischemic T wave

"35 y.o. man presents with indigestion and chest fullness brought on by chili peppers and relieved by antacids."

Early repol - more common in young

The __on lead V5 is common in early repol

"J notch"

"24 year old student, recently recovered from upper respiratory infection, presents w fever and chest pain."


What EKG changes should make you think pericarditis?

Diffuse ST elevations across multiple leads

"45 y.o. pilot in office for a routine physical."

RBBB - see RSR'

"85 year old female undergoing preop evaluation prior to hip surgery. Anesthiologist is asking if a pacemaker is needed."

LBBB - remember mneumonic "WiLLiaM MaRRoW"
(looks like rabbit ears)

How do you tell a RBBB from a LBBB?

R - M in v1 and W in v6
L - W in v1 and M in v6

"55 year old postman presents with severe chest pain after being chased by a pit bull."

acute STEMI

"85 year old retiree with hypotension and chest ache for 10 hours"


Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions and try again


Reload the page to try again!


Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

Voice Recording