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How to read ECGPG corner
Mr do not Miss
Lead reversal and ECG artefacts
Technology does not understood science of ECG
Do not believe in COMPUTERIZED ECG INTERPRETATIONS
At least 14 observationsbefore answering
Standardization
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.
Rhythm
Sinus rhythm bradycardia or tachycardia SR with APBs or VPBs SR with AV block
Nonsinus:PSVT), Afib or flutter, VT and AV junctional escape
Sinus rhythm
Discrete P waves that are always positive (upright) in lead II (and negative in aVR
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
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 the Wolff-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.
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.
QRS Interval
0.1 sec (100 ms) or less, measured by eye
110 ms if measured by computer
QT/QTc Interval
Shortened :hyperkalaemia and digitalis effect
Prolonged:hypocalcemia or hypokalemia, drug effects (quinidine, procainamide, amiodarone, or sotalol), or myocardial ischemia
QRS Voltage
Stick to criteria for Normal /LVH/RVH
QRS Axis Frontal plane
Normal: −30° to +100°
R wave progression
Inspect leads V1 to V6
Normal increase in R/S ratio occurs as you move across the chest
Poor: (small or absent R waves in leads V1 to V3) AWMI
The term reversed R wave progression Tall R waves in lead V1 that progressively decrease in
amplitude:RVH, posterior (or posterolateral) infarction, and dextrocardia
Q,T,U Document changes
U Wave U Waves Look for prominent U waves. These waves,
usually most apparent in chest leads V2-V4, may be a sign of hypokalemia or drug effect or toxicity (e.g., ami-odarone ami-odarone, dofetilide, quinidine, or sotalol).
Normal frontal loop:1.q in II/III/aVF2.No q in I/AVL
Counter clock loop in frontal plane:1.q in AVL2.No q in II/III/AVF
(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, and V6 slightly depressed in leads V1 and V2 (13) T waves—inverted in leads II, III, aVF, and V3 through V6 (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
Calcium and 12 Lead ECG
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 leads V1-V2
Incomplete right bundle branch block (IRBBB)
S1Q3T3 pattern—an S wave in lead I, a Q wave in lead III, and an inverted T wave in lead III. Although this is only occasionally seen with pulmonary embolus, it is quite suggestive that a pulmonary embolus has occurred.
I can only give you hint because I know less