ECG Dr. Mohammed Shaat Modified by : Dr. Amal Al Maqadma.
Electrocardiography It is a voltage difference, record the electrical activity of the heart as well as valuable information about the heart function and structure. Willem Einthoven 1924
Leads (lead x electrode) • LIMB LEADS I II III AVF AVL AVR • CHEST LEADS V1 V2 V3 V4 V5 V6 bipolar unipolar
ECG Leads - Views of the Heart • V1 & V2 Septum • V3 & V4 anterior +Right Ventricle • V5 & V6 Lateral Left Ventricle • II+III+AVF inferior border
ECG Paper ECG Speed 25mm/sec
P wave • Represent the electrical activity of both atria ( atrial depolarization) • The depolarization slow within the AV node, there is a brief delay or PAUSE before the depolarization conducted to the ventricles
Normal duration <0.12 secAbsent P wave:Atrial fibrillation SA BlockAV RhythmPeak P wave:Atrial hypertrophy
PR interval • Normally :0.12-0.2sec • Prolonged in : heart block. • Short in : W-P-W syndrome.
QRS Complex • Represent the electrical activity of both ventricles. • Ventricular depolarization( initiation of the ventricular contraction
QRS Complex • Q wave • Rwave: • S wave : • : Normal QRS duration < 0.12 sec
QRS Complex • Q wave • first downward deflection . • septal depolarization. • 0.04sec.
Rwave: first upwarddeflection. height: 5-8 mm. early ventricular depolarization
ST - Segment • ST segment: the plateau phase of ventricular repolarization. • Isoelectric or> or<1mm. • If the ST segment elevated or depressed beyond the normal baseline this usually sign of serious pathology. (MI)
T- Wave • T-wave :represent rapid phase of ventricular repolarization. peaked Twave: • early MI • hyperkalemia • Black races Inverted : • MI . • Ventricular hypertrophy. • Hypokalemia • Digoxin
Q-T interval • 0.4sec in HR 70 • Prolonged in : • Hypocalcemia • hypomagnesemia
U wave • repolarization of the interventricular septum. • low amplitude • Prominent: suspect hypokalemia, hypercalcemia or hyperthyroidism
J wave • represents the approximate end of depolarization and the beginning of repolarization • camel-hump sign . • Hypothermia • hypocalcemia.
Low voltage ECG • Obesity • Emphysema • COPD • Severe hypothyroidism
Rate • Normal heart rate 60-100/ min • < 60 called bradycardia • >100 called tachycardia
300 HR= No. of Large box btw R-R 1500 HR= No. of Small box btw R-R
RHYTHM • Look For The Distance between Identical waves. • Most commonly used R-R
AXIS At any point during depolarization and repolarization electrical potential are being propagated in different directions. Most of these cancel each other out and only the net force is recorded. This net is called AXIS or cardiac VECTOR