Transcript ECG

heart muscle
smooth muscle
excitation contraction coupling
striated muscle
Description of curves
P = Impulse spread through atria
PQ = neutral (isoelectric) line after
depolarisation of all atria
myocardium
QRST = ventricle complex
Q = negative oscillation –
beginning of ventricle
depolarisation in septum
R = continue of depolarisation
wave through the ventricle
S = negative oscillation –
activation of last part of ventricle
myocardium in left ventricle base
ST = neutral (isoelectric) line after
ventricle depolarisation (plató
phase in action potential)
T = repolarisation from epicardium
to endocardium
According to the amplitude, lower or upper case is used
> 5 mm - Q, R, S
< 5 mm - q, r, s
-90o
-120o
aVF
-60o
III
-30o
-150o
aVL
I
+180o
+150o
aVR
II
+120o
+90o
+60o
0o
+30o
Action potential
SA node
Myocardium
Examples of pathological ECG
Sinusoidal rhythm
and fibrilation of atria & AV block
Fibrilation of ventricles
Heart attack
AV block
1. Blokáda levého raménka Tawarova
(BLRT) (synonymum: LBBB - left bundle
branch block)
According to the QRS interval
-complet block - QRS > 0,12s
-incomplet - QRS < 0,11s
Incidence: heart attack (congenital LBBB extremely rare. aortal stenosis or
diphteria)
Blokáda pravého raménka Tawarova (BPRT)
(RBBB - right bundle branch block)
Incidence: RBBB heart attack, chronic cor pulmonale, atrium septal defect.
incomplete RBBB normal in cyclist and boaters (volume load to right ventricle).
supraventricular
ventricular
extrasystole
reentry
ECG leads
R
On the right arm, avoiding bony prominences – RED
L
In the same location that RA was placed, but on the left arm this time – YELLOW
G
On the right leg, avoiding bony prominences – BLACK (ground)
LL
In the same location that G was placed, but on the left leg this time – GREEN
V1
In the fourth intercostal space (between ribs 4 & 5) just to the right of the sternum
(breastbone).
V2
In the fourth intercostal space (between ribs 4 & 5) just to the left of the sternum.
V3
Between leads V2 and V4.
V4
In the fifth intercostal space (between ribs 5 & 6) in the mid-clavicular line (the
imaginary line that extends down from the midpoint of the clavicle (collarbone).
V5
Between leads V4 and V6
V6
Horizontally even with V4 and V5 in the midaxillary line. (The midaxillary line is the
imaginary line that extends down from the middle of the patient's armpit.)
Leads and electrodes
Limb
Thoracic
Evaluation of the ECG
• Pulse: regular, irregular
• Rhythm: sinusoidal or other (nodal = from AV
node)
• Frequency: Normal 60-90 pulses/min
• Heart electrical axis inclination: normal (the
same way), to left (outside), to right (inside) just
generally from limb leads I and III. Exactly by using
Einthoven’s triangle.
• Description of waves, their duration and intervals.
Frequency
• Heard frequency = 72 pulses/min, = pulse interval
0.83 s
• During relaxation the frequency changes based of
the respiration (RESPIRATION ARYTMIA) =
inspiration - increased frequency, expiration –
decreased frequency.
• Bradycardia = fysiological = deep long-term
inspiration, deep forward bend and knee band =
reflex changes of vagal tonus.
• Tachycardia = fysiological = swallow (decrease of
vagal tonus), change of position from lying or sitting
to standing (ORTOSTATIC REACTION).
Examples of pathological ECG
Sinusoidal rhythm
and fibrilation of atria & AV block
Fibrilation of ventricles
Heart attack
reentry
Electric expression of heart
action
Ganong: Physiology
• Record of summary electric activity of hear is called electrocardiogram
(ECG).
• ECG curve is summary potential that is a result of all action potentials of
myofibers.
• Beginnings of QRS complex and action potentials of ventricles are the same
and ending of ventricle action potentials is the same as the end of wave T.
heart electrical axis
average (largest) electrical heart vector)
if positive in the lead
aVF (above left) and
positive in the lead I
(right)
then must lie where
overlap (right)
Lead I – positive
amplitude
Lead I – negative
amplitude
-90o
-120o
aVF
-90o
-60o
-120o
III
-30o
-150o
aVL
I
+180o
+150o
0o
aVR
aVF
-60o
III
-30o
-150o
aVL
I
+180o
+150o
aVR
+30o
II
+120o
+60o
+90o
0o
+30o
II
+120o
+60o
+90o
Heart electrical axis inclination
• Each myocyte produce dipole
during action potential - vector
with specific dimension and
direction.
• Cell vector head from
depolarised to polarised part, i.e.
in direction of action potential
spread.
• If the cell is completely
depolarised (plató phase) or
polarised (resting phase), vector
is neutral.
• Electrical heart vector is a
summary of all cell’s vectors in
one time point
Normal value is -30° až +105°
Shift of the axis to right above 105 °
= hypertrophy of RV or long and
slim
Shift of the axis to left below -30°
= hypertrophy of LV or obese
people