ECG Analysis

Question 1

P-Wave

Answer 1

Atrial Depolarization

<= 0.11

Abnormalities:

1. Myocardial Ischaemia/Myxoma
2. Amplitude increases in cardiac or specific atrial hyperthrophy
3. Amplitude is smaller in hyperkalaemia
4. P-wave is prolonged in left atrial hypertrophy(mitrial stenosis) and right atrial hypertophy(Pulmonary stenosis or tricuspid stenosis)

Question 2

QRS Complex

Answer 2

Ventricular depolarization

0.04-0.10(.12)

Prolongation:

Ventricular(L or R bundle branch) block
Ectopic Ventricular Pacemakers
Ventricular Hypertrophy
Hyperkalemia

Question 3

T-Wave

Answer 3

Ventricular Repolarization

<= 0.2

Normally asymetrical,Normaly inverted in lead iii, aVR and V1

The t-wave poalrity is opposite to the dominant QRS defelction polarity when ventricular mucle conduction is delayed.

Hyperkalaemia: Tall peaked T wave

Hypokalaemia: Decreased T wave amplitude.

Digitalis toxicity can cause T-wave inversion or biphasic waves

Acute myocardial ischemia causes inversion

Question 4

P-R Interval

Answer 4

AV conduction time(From atrial depolarization to beginning of ventricular depolarization)

0.12-0.20(.21)

Prolonged and constant in first degree AV block and in an second degree av block,it is prolonged and may be constant

Question 5

R-R Interval

Answer 5

Time between successive QRS complexes

0.83

Prolonged in sinus bradycardia/Sympatholytic/Parasympathomimetic drugs pr excessive vagal stimulation

Shortened with sinus tachycardia

Question 6

QT Interval

Answer 6

Complete ventricular depolirization and ventricular repolarization

0.25-.43 Males/0.44 in premenopausal females

Prolonged due to congenital long QT syndrome-Drugs(Antiarryttimic drugs such as amiodarone0

or

Electrolyte disorders: Hypokalaemaia,Hypomagnesaemia and Hypocalcaemia

Question 7

J Point at the beginning of ST Segment

Answer 7

ST segment represents platueau phase 2 of cardiac potential

Upward/Downward deflection:A current of injury that can be caused by a myocardial infarct/Ischamiae or Cardiac Trauma or Myocarditis

Question 8

U-Wave

Answer 8

Repolarization of ventricular papilary muscle

<= 0.1

Hypokalaemia can increase the amplitude

Question 9

True/False: Atrial repolarization occurs simultanoeusly with the QRS complex

Answer 9

True,Therefore these ECG deflections are not normally seen.