Download Pathological Q-wave

Introduction to ECG
Recognition of
Myocardial Infarction
Possibilities of an ECG of
diagnostics
The ECG allows:
 to diagnose a myocardium ischemia
 to diagnose necrosis a myocardium
 To define localisation of necrosis
 Extensiveness of defeat and depth
necrosis
 Process stage
 Some complications
Changes in a myocardium at CHD
 At
CHD in a cardiac muscle processes of
an ischemia, injury and necrosis develop
depending on expressiveness and
character of damage of coronary arteries.
 Each process in a myocardium has the
ECG signs.
ECG at stenocardia
ECG a stenocardia at a painful attack
 Horizontal or down sloping slantwise
downwards the directed depression of
segment S-Т (below an isoline) on 1 mm
 Or segment lifting S - Т above an isoline>
1мм a painful ischemia of a myocardium.
Ischemia
 Ischemia
transitory disturbance of
coronary arteries.
 At the ECG reflect changes wave Т и
segment ST, transitory.
Ischemia

Ischemia in
subepicardial at the
ECG appear
transitory negative
symmetrical Т wave.
Ischemia

Subendocardial
ischemia at the ECG
appear transitory high
positive symmetrical
wave Т.
Ischemia
Injury
At a long ischemia of a myocardium > 30 minutes, the
ischemia leads more to radical changes in a
myocardium, accompanied by infringements of
biochemical processes in a cardiac muscle that leads to
infringements of processes repolarization longer period.
 On an ECG this process finds reflexion in change of
segment ST and T wave.
 At restoration of a coronary circulation ischemic
changes remain some days (<10 days), that clinically
reflects a condition of an unstable stenocardia (the
Acute coronary syndrome)

Injury

At the subepicardial
injury (or transmural
injury) on the ECG
appear elevation ST
segment duration more
exceed time heart
attack.
Injury

At the
Subendocardial
injure on the ECG
appear depression
ST segment
duration more
exceed time heart
attack.
Injury
 At
restoration of coronary blood
circulation ischemia and injure processes
do not lead to morphological changes in a
myocardium.
 At a remaining ischemia and the injure
caused by the termination of a coronary
circulation morphological changes in a
myocardium in necrosis of cardiac
muscle-development of AMI.
Necrosis
Necrosis a cardiac muscle it is reflected in
an ECG by infringement of processes
depolarization, that is reflected by
changes in complex QRS
Necrosis
Necrosis
At the ECG disturbance depolarization:
 Pathological Q-wave (QS, or QR);
 Elevation RS–T segment and
 Inverted Т waves.


In the lead which
are in a zone
opposite from centre
necrosis, are
registered mirror
changes - to Q wave
there corresponds R,
and to r (R) wave - a
s (S) wave.
If over a zone of MI
segment ST is raised
by an arch upwards
on opposite sites it is
lowered by an arch
downwards
 At
the healthy person in the lead reflecting
potential LV (V5-6, I, aVL), the physiological
q wave, a reflecting vector of excitation of a
IVS of heart can be registered.
 The physiological q wave in any leads, except
aVR, should not be more than 1/4 teeth R
with which it is written down (25% of Rwave amplitude), and is more long 0.03 sec.
Stages of development of MI
At sharp infringement of a coronary circulation
in a heart muscle 3 processes consistently
develop:
 ischemia
 injure
 necrosis (infarct).
 Duration preliminary to a heart attack of phases
depends on many reasons: degrees and speeds of
infringement of a circulation, development
collaterals, etc., but usually they last from several
tens minutes, till several o'clock.
Evolution of Acute MI
 The
ECG changes depending on time
which has passed from the beginning of
formation by MI.
 Usual ECG evolution of a Q-wave MI;
 Not all of the following patterns may be
seen;
 The time from onset of MI to the final
pattern is quite variable and related to
the size of MI, the rapidity of reperfusion
(if any), and the location of the MI.
A. Normal ECG prior to MI
B. Hyperacute T wave
changes - increased T
wave amplitude and
width; may also see ST
elevation
C. Marked ST elevation with
hyperacute T wave
changes (transmural
injury)
D. Pathologic Q waves, less
ST elevation, terminal T
wave inversion (necrosis)
 (Pathologic Q waves are
usually defined as
duration >0.03 s and
>25% of R-wave
amplitude or > ¼ from R)
E. Pathologic Q waves, T
wave inversion (necrosis
and fibrosis)
F. Pathologic Q waves,
upright T waves (fibrosis)
Evolution of Acute MI in acute (а–д),
subacute (е-ж) and scarring (з) stages
Peracute stage
 Peracute
stage (tо 2-х h from start MI).
Within several minutes after the termination
of a coronary circulation and occurrence
heart attack in a cardiac muscle the zone
usually comes to light
 Subendocardial eschemia, (appear high Т
wave and depression RS–Т segment.
 In practice these changes are registered seldom
enough, and the doctor deals with later ECG
signs of the sharpest stage MI.
Peracute stage
 When

the zone of ischemic injure extends to
epicardium, on an ECG displacement of
segment RS-Т above an isoline is fixed
(transmural ischemic injure).
Segment RS-Т thus merges with positive Т
wave, forming the so-called monophase
curve
Peracute stage
a) subendocardial
ischemia
 б) subendocardial
ischemia and
subendocardial
injure
 в) transmural
injury

Acute stage
Is characterised fast, during 1 - 2 day, formation of
pathological Q or complex QS and decrease in
amplitude of R wave that specifies in formation and
zone expansion necrosis.
 Simultaneously within several days over a zone
necrosis displacement of segment RS-T above an
isoline and merging with it positive remains in the
beginning, and then negative Т wave, and in an
opposite wall to a zone necrosis the ischemia of a
myocardium in the form of depression of segment ST
remains an ischemia of a myocardium in the form of
depression of segment ST.

Acute stage
 In
some days segment RS-T comes nearer to
an isoline, and by the end of 1st week or in
the beginning of 2nd week of disease
becomes isoline, that testifies to reduction of a
zone of ischemic injure.
 Negative coronary Т wave it goes deep and
becomes sharp symmetric and pointed
(repeated inversion of a T wave).
Acute stage
Direct signs of a sharp stage
MI with Q wave
Pathological Q wave (Qr or QS);
 Elevation RS–T segment and
 Inverted Т waves.

Subacute stage
 In
subacute stages MI registers pathological Q
wave or complex QS (necrosis) and the
negative coronary Т wave (ischemia), which
amplitude, since 20-25-days MI, gradually
decreases.
 Segment RS-T is located on an isoline.
 Signs a myocardium ischemia in the given
stage disappear.
Subacute stage
Fibrosis stage

The cicatricial stage is characterised by IT
preservation for many years pathological Q
wave and complex QS (QR or Qr) and
presence of negative, smoothed or positive
Т wave.
Fibrosis stage
Depth of necrosis
 At
transmural necrosis on ECG
present QS complex;
 At nontransmural necrosis present Qr
or QR complex.
Q wave MI: a) transmural necrosis,
б) nontransmural
Localization MI
Localization MI
Leads
Occlusion of artery
An anterior
V1 - V4
Anterior Descending
branch of the left CA
Inferior
(diaphragmatic)
II, III, aVF
Branches of either the
rigth or left CA
Lateral
I, aVL, V5, V6
Circumflex branch of
the left CA
Posterior
Lardge R in V1-2,
May be Q in V6
Mirror test
Right CA or one of its
branches
ECG with regions of the heart
highlighted
What part of the heart is
affected ?
 II,
III, aVF =
Inferior Wall
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
Inferior Wall MI
Based on the ECG, which vessel in
the heart is blocked?
 II,
III & aVF = Inferior Wall MI =
Right Coronary Artery
blockage
Which part of the heart is affected ?
• Leads V1, V2, V3, and V4 =
Anterior Wall MI
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
Anterior Wall MI
Based on the ECG, which vessel in
the heart is blocked?
 V1
- V4 = Anterior Wall
(Left Ventricle) =
Left Anterior
Descending Artery
Blockage
What part of the heart is
affected ?
 I,
aVL, V5 and V6
Lateral wall of left ventricle
I
aVR
V1
V4
II
aVL
V2
V5
III
aVF
V3
V6
Lateral Wall MI
Based on the ECG, which vessel in
the heart is blocked?

I, aVL, V5 + V6 =
Lateral Wall =
Circumflex Artery
Blockage

ECG at the
anterior MI

ECG at the anterior
MI and apex
Diagram of a MI (2) of the tip of the
anterior wall of the heart after occlusion
(1) of a branch of the LCA

ECG at the
lateral MI

ECG at MI of all
anterior wall – I,
avL, V1-V6
ECG at the
inferior MI
 In I, aVL, V1 –
V4 leads
mirror change

Non-Q Wave MI
 Recognized
by evolving ST-T changes over
time without the formation of pathologic Q
waves (in a patient with typical chest pain
symptoms and/or elevation in myocardialspecific enzymes)
 Although it is tempting to localize the nonQ MI by the particular leads showing ST-T
changes, this is probably only valid for the
ST segment elevation pattern
Non-Q Wave MI
Evolving ST-T changes may include any of
the following patterns:
 Convex downward ST segment depression only
(common) > 48 h
 Convex upwards or straight ST segment
elevation only (uncommon)
 Symmetrical T wave inversion only (common)
> 10 days
 Combinations of above changes
Non Q wave MI: в) depression ST
segment, г) negative symmetrical Т
wave
Non-Q Wave MI
Non-Q Wave MI
Non-Q Wave MI
Summary
 After
completing an ECG, look at each of
the leads for ST segment changes
 Remember the three I’s:
Ischemia, Injury, and Infarct !!
 Identify the section of the heart (and vessel
supplying it) affected by the blockage
according to the groups of leads changing in
the ECG
 Remember the symptoms that would
prompt you to obtain an ECG!