ECG

Question 1

Who discovered mechanism of ECG?

Answer 1

Willem Einthoven.
1924
Nobel prize

Question 1

Who discovered mechanism of ECG?

Answer 1

Willem Einthoven.
1924
Nobel prize

Question 2

The 12 lead ECG.

Answer 2

3 - bipolar leads

9- unipolar leads

Question 3

Unipolar leads in 12 lead ECG.

Answer 3

3 - augmented limb leads (by Emanuel Goldberger)

6 - chest leads

Question 4

Bipolar leads in 12 lead ECG.

Answer 4

Limb leads
Leads 1, 2 ,3.
Placed based on Einthovens triangle.
Lead1 - (-ve) end is Right arm, (+ve) end is Left arm
Lead2 - (- ve) end is Right arm, (+ve) end is Left leg
Lead3 - (-ve) end is Left arm, (+ve) end is Left leg

Lead1 + Lead3 = Lead2

Question 5

Dimensions in an ECG.

Answer 5

Large square.
5×5 small squares = 5mm×5mm
0.20s in horizontal
0.5mV in vertical

Small square.
1×1mm
0.04s in horizontal
0.1mV in vertical

Question 6

Augmented unipolar limb leads.

Answer 6

aVR- (+ve) end is Right arm, (-ve) end is Left arm+Left leg
aVL- (+ve) end is Left arm, (-ve) end is Right arm+Left leg
aVF- (+ve) end is Left leg, (-ve) end is Right arm+Left arm

The size of potential recorded is increased by 50%

Question 7

Intervals and segments in ECG.

Answer 7

PR interval - 0.12 - 0.20s
AV conduction time

QT interval - 0.35-0.43s
Ventricular depolarisation and repolarisation events

RR interval - 0.6 - 1s
To calculate HR = 1500/no. of small squares b/w 2 R waves.

Question 9

Normal ECG waveforms and durations.

Answer 9

P wave - atrial depolarisation
                0.10s
                < 0.25mV
P wave in V1 is biphasic.
Initial component- R. atrial activity 
Terminal component- L. atrial activity 

QRS complex - ventricular depolarisation
0.08-0.10s
1-1.5mV
Normal QRS axis ranges from -30° to +100°

T wave - ventricular repolarisation

      0. 2s
     0. 3mV

U wave - repolarisation of his-purkinje system
1/10th of a T wave
Best recorded in anterior precordial leads V2 V3

Question 10

Corrected QT interval.

Answer 10

QT interval changes with HR.
Bazette formula
Q-Tc= Q-T/square root of R-R

Question 10

WPW syndrome

Answer 10

PSVT
Accessory pathway that connects atrium to ventricle is called bundle of Kent.
Delta wave : initial portion of QRS complex with a slow upstroke.

Question 11

12 leads and which part of heart do they view?

Answer 11

V1, V2 septal (LAD artery)
V3, V4 ant wall (LAD artery)
V5, V6, 1, aVL lateral wall (circumflex artery)
2, 3, aVF inferior wall (right coronary artery)

Question 13

Tall p wave (pulmpnale) conditions?

Answer 13

> 2.5mm in height

Right atrial enlargement.

Question 13

Absent P wave conditions?

Answer 13

AF

Hyperkalemia

Question 14

Wide P wave (mitrale) conditions?

Answer 14

P wave >2.5mm in width

Left atrial enlargement

Question 16

Wide QRS complex conditions?

Answer 16

>0.08s
BBB
Hyperkalemia
WPW syndrome
Amiadarone (anti-arrhythmic drug)
Myocarditis

Question 17

Left axis deviation.
meaning?
conditions?

Answer 17

meaning QRS axis more negative than -30degrees

Obese people (normal variant)
LVH
Left ant hemiblock
Inferior wall MI

Question 18

Right axis deviation.
meaning?
conditions?

Answer 18

meaning QRS axis more than +100degrees.

Thin, tall people (normal variant)
RVH
Left post hemlock
Lateral wall MI
Chronic lung diseases
Dextrocardia

Question 19

Inverted T-wave conditions?

Answer 19

Hypo- kalemia
Hypo- thyroidism
Hypo- thermia
MI
Cardiomyopathy
Pericarditis
CVA (SAH)
Pulmonary embolism
Drugs- Digitalis, Quinidine

Question 20

Tall T- waves conditions?

Answer 20

Hyper- kalemia (narrow based tented T-wave)

MI (broad based T-wave)

Question 21

Abnormal U-waves.
meaning?
conditions?

Answer 21

amplitude >1.5mV

MCC- drugs- Amiadarone, Quinidine, sotalol, dofetilide.
Hypo- kalemia

Inverted U-wave - Ischemic heart disease

Prominent u-waves - marker of increased susceptibility to TORSADES DE POINTES type of Vent. tachy.

Question 22

Prolonged PR- interval. conditions?

Answer 22

1st degree Heart block - PR prolongation >0.20s
2nd degree HB - PR interval prolongation followed by missed beats.
* Mobitz type 1 block- gradual lengthening of PR interval till a P-wave is not followed by a QRS complex. a/k/a WENKEBACH PHENOMENON
*Mobitz type 2 block - ventricular beat follows every 2nd or 3rd atrial beat.

3rd degree HB- conduction from atrium-ventricle totally blocked.
idioventricular rhythm.
low ventricular rate –> decreased brain perfusion –> dizziness and fainting (STOKES ADAMS .S).

Question 23

Short PR interval?

Answer 23

means PRinterval < 0.12s.

MCC- Vagolytic drugs- Atropine.
WPW syndrome
Down-Ganong-Levine syndrome.

Question 24

Short QT interval?

Answer 24

Hyper- kalemia
Hyper- calcemia
Hyper- thermia
Acidosis
Digitalis

Question 25

Prolonged Qt-interval?

Answer 25

Hypo- calcemia
Acute-MI
Rheumatic fever
Congenital QT syndromes- ROMANO-WARD.S,
                                              JERVELL-LANGE-NIELSEN.S
Drugs - Amiadarone
             Quinidine
             Terfenadine
              Cisapride

Question 26

ECG changes in Hyperkalemia?

Answer 26

Tall T-waves- earliest, most characteristic and most consistent finding.
QT-inerval short
Low amplitude P-waves
Prolonged AV conduction.

Question 27

ECG changes in Hypokalemia?

Answer 27

T-wave inversion
QT-interval prolonged
Prominent U-waves
ST-segment depression.

Question 28

ECG changes in Hypercalcemia?

Answer 28

QT-interval short
ST-segment short
Wide QRS-complex
Increased QRS voltage.

Question 29

ECG changes in Hypocalcemia?

Answer 29

QT- interval prolonged

Lengthening of ST-segment.