Investigation

Question 1

ECG : assess cardiac rhythm and con-
duction as well as the diagnosis of myocardial ischaemia and infarction.

Answer 1

Atrial depolarization _p
ventricular dep_qrs
ventricular repolarization-t

Question 2

P-R interval denotes the duration of conduction to AV Node

Answer 2

Normal = 0.12–0.20 sec. Prolongation denotes
impaired atrioventricular nodal conduction. A
short PR interval occurs in Wolff–Parkinson–
White syndrome

Question 3

Left or Rt bundle branch block cause wide QRS complex

Answer 3

QRS duration If > 0.12 sec, ventricular conduction is
abnormal (left or right bundle branch block)
QRS amplitude Large QRS complexes occur in slim young
patients and in patients with left ventricular
hypertrophy

Question 4

P wave
Q wave

Answer 4

Tall p waves-RA enlargement
Notched P wave- LA enlargement
prev MI Q wave
ST segment:

Question 5

ST segment

Answer 5

ST elevation may signify myocardial infarction,
pericarditis or left ventricular aneurysm; ST
depression may signify ischaemia or infarction

Question 6

T wave
QT interval

Answer 6

T-wave inversion has myocardial ischaemia or infarction, and
electrolyte disturbances

QT interval Normal <0.44sec (male), 0.46 sec (female)
corrected for heart rate. QT prolongation may
occur with congenital long QT syndrome, low K+Mg2+
or Ca2+ , and some drugs

Question 7

ECG leads

Answer 7

One electrode is attached to each limb and six elec-
trodes are attached to the chest. In addition, the left arm, right arm and

left leg electrodes are attached to a central terminal acting as an additional virtual electrode in the centre of the chest

Question 8

Leads I, II and III are the dipole limb leads and refer to recordings
obtained from pairs of limb electrodes. Lead I records the signal between
the right (negative) and left (positive) arms. Lead II records the signal
between the right arm (negative) and left leg (positive). Lead III records
the signal between the left arm (negative) and left leg (positive).

Answer 8

electrical activity between a limb electrode and
a modied central terminal. For example, lead aVL records the signal
between the left arm (positive) and a central (negative) terminal, formed
by connecting the right arm and left leg electrodes. Similarly
augmented signals are obtained from the right arm (aVR) and left leg
(aVF). These leads also record electrical activity in the frontal plane, with
each lead 120° apart. Lead aVF thus examines activity along the axis
+90°, and lead aVL along the axis 30°, and so on.

Question 9

Exercise testing

Answer 9

Angina on exertion is a positive finding
 To evaluate stable angina
To assess prognosis following myocardial infarction
 To assess outcome after coronary revascularisation, e.g. coronary angioplasty
 To diagnose and evaluate the treatment of exercise-induced arrhythmias

Question 10

High risk
Contraction of Stress ECG

Answer 10

Low threshold for ischaemia (within stage 1 or 2 of the Bruce Protocol)
 Fall in blood pressure on exercise
 Widespread, marked or prolonged ischaemic ECG changes
 Exercise-induced arrhythmia
Stress
testing is contraindicated in the presence of acute coronary syndrome,
decompensated heart failure and severe hypertension.

Question 11

The main
indication for ambulatory ECG is in the investigation of patients with

suspected arrhythmia,

Answer 11

BNP Serum concentra-
tions are elevated in conditions associated with LV systolic dysfunction.
detect minor degrees of myocardial damage, so that elevated
plasma troponin concentrations may be observed in conditions other

than acute MI, such as pulmonary embolus, septic shock and pulmo-
nary oedema.