Part III
Atrial Enlargement and
Ventricular Hypertrophy
薛小临
(1) Left Atrial Enlargement
Lead II
 Duration of P wave ≥0.12 sec. ;
 P wave become bifid (P "mitrale");
 The distance of two peak ≥ 0.04sec.
Lead V1


P wave become biphasic;
Ptfv1  - 0.04 mm·sec
Right Atrial Enlargement
Lead II


P wave is peaked (P "pulmonale");
Amplitude of P wave ≥0.25 mV in limb
leads.
Biatrial Enlargement
Lead II

P wave duration and amplitude
both increased.
Left Ventricular Hypertrophy
A. Increased voltage
 SV1 + R V5 >3.5mV (female),
4.0mV (male);
 Rv5 or Rv6 > 2.5 mV;
 RI > 1.5mV;
 RaVL > 1.2mV;
 RaVF > 2.0 mV;
 RI + SIII > 2.5 mV;
B. Left axis deviation
C. ST depression and T inversion in V5-6.
Right Ventricular Hypertrophy
A. Increased voltage (adults over 30)
 R/S ratio in V1 > 1.0;
 R/S ratio in V5 or V6 ≤ 1.0;
 R/q or R/S ratio in aVR≥1;


R V1+ S V5 >1.05mV (severe>1.2mV);
RaVR>0.5mV;
B. Right axis deviation ≥ +900 (severe > +1100).
C. ST depression and T inversion V1-2.
Biventricular Hypertrophy



A. Normal ECG.
B. One ventricular hypertrophy.
C. Biventricular Hypertrophy.
Part VI
Myocardial Ischemia and
Myocardial infarction
ECG of myocardial ischemia shows:

ST segment depression;

ST segment elevation( coronary spasm);

Inverted, diphasic, low T wave.
Myocardial infarction
(1) Basic changes
 “Hyperacute” T Waves. Tall peaked T waves,
often appear as the earliest ECG sign of acute
MI.

ST Elevations. The ST segment elevated in
one or more leads and may be straightened
and fuse with the T wave (mono-phasic curve)

Pathologic Q Waves. the sudden developed
Q wave may indicate an acute MI.

T Wave Changes. The elevated ST
segments return to the baseline, and
deep symmetrical T waves appear in
these leads. Tall, symmetrical, upright T
waves will appear in reciprocal leads at
the same time.
(2) Progressive ECG changes
(3) Localization of the ECG patterns
Leads with Abnormal Q Waves in MI
Leads with Abnormal Q Waves
location of MI
V1  V3
Anteroseptal
V3  V5
Anterior
I, aVL, V5  V6
Lateral
V1  V6
Extensive Anterior
II, III, aVF
Inferior
(4) Old myocardial infarct

A definitive diagnosis of old myocardial
infarct depends on the presence of a
pathological Q wave