5. Standardizati
on
Usual 1 mV = 10 mm
In special cases ECG may be intentionally recorded at one-half
standardization (1 mV =5mm) or two times normal standardization
(1 mV = 20 mm). However, overlooking this change in gain may lead
to the mistaken diagnosis of low or high voltage.
6. Rhythm
Sinus rhythm
bradycardia or tachycardia
SR with APBs orVPBs
SR with AV block
Nonsinus:PSVT),Afib or flutter,VT and AV junctional escape
7. Sinus rhythm Discrete P waves that are always positive (upright) in lead II (and
negative in aVR
8. Heart Rate
Normally, the ventricular (QRS) rate and atrial (P) rates are the
same (1:1 AV conduction)
Tachycardia >100
Bradycardia <60
Irregular
Regularly irregular :Wenchebach’s
Irregularly irregular :Fib
9. PR Interval
The normal PR interval (measured from the beginning of the P
wave to the beginning of the QRS complex) is 0.12 to 0.2 sec
First-degree AV block
A short PR interval with sinus rhythm and with a wide QRS
complex and a delta wave is seen in theWolff-Parkinson-White
(WPW) pattern
A short PR interval with retrograde P waves (negative in lead II)
generally indicates an ectopic (atrial or AV junctional) pacemaker.
10. P wave
Normal not exceed 2.5 mm in amplitude and is less than 3 mm
(120 ms) wide in all leads
Tall, peaked P waves may be a sign of right atrial overload (P
pulmonale)
Wide (and sometimes notched P) waves are seen with left atrial
abnormality.
11. QRS Interval
0.1 sec (100 ms) or less, measured by eye
110 ms if measured by computer
12. QT/QTc
Interval
Shortened :hyperkalaemia and digitalis effect
Prolonged:hypocalcemia or hypokalemia, drug effects (quinidine,
procainamide, amiodarone, or sotalol), or myocardial ischemia
15. R wave
progression
Inspect leadsV1 toV6
Normal increase in R/S ratio occurs as you move across the chest
Poor: (small or absent R waves in leadsV1 toV3)
AWMI
The term reversed R wave progression
Tall R waves in leadV1 that progressively decrease in
amplitude:RVH, posterior (or posterolateral) infarction, and
dextrocardia
17. UWave
U Waves Look for prominent U waves.These waves, usually most
apparent in chest leadsV2-V4, may be a sign of hypokalemia or
drug effect or toxicity (e.g., ami-odarone ami-odarone, dofetilide,
quinidine, or sotalol).
20. (1) standardization—10 mm/mV; 25 mm/sec
(2) rhythm—normal sinus
(3) heart rate—75 beats/min
(4) PR interval—0.16 sec
(5) P waves—normal size
(6) QRS width—0.08 sec (normal)
(7) QT interval—0.4 sec (slightly prolonged for rate)
(8) QRS voltage—normal
(9) QRS axis—about 30° (biphasic QRS complex in lead II with positive QRS complex
in lead I)
(10) R wave progression:early precordial transition with relatively tall R wave in lead
V2
(11) abnormal Q waves—leads II, III, and aVF
(12) ST segments: elevated in leads II, III, aVF,V4,V5, andV6 slightly depressed in
leads V1 and V2
(13)T waves—inverted in leads II, III, aVF, andV3 throughV6
(14) U waves—not prominent. Impression:This ECG is consistent with an
inferolateral (or infero-posterolateral) wall myocardial infarction of indeterminate
age, possibly recent or evolving. Comment:The relatively tall R wave in lead V2 could
reflect loss of lateral potentials or actual posterior wall involvement
EXAMPLE
22. What ECG
findings may
be present in
pulmonary
embolus?
Sinus tachycardia (the most common ECG finding)
Right atrial enlargement (P pulmonale)—tall P waves in the
inferior leads
Right axis deviation
T wave inversions in leadsV1-V2
Incomplete right bundle branch block (IRBBB)
S1Q3T3 pattern—an S wave in lead I, a Q wave in lead III, and an
invertedT wave in lead III.Although this is only occasionally seen
with pulmonary embolus, it is quite suggestive that a pulmonary
embolus has occurred.
