ELECTROCARDIOGRAPHY = methods enabling to register electrical changes caused by heart activity from body surface.
1893 Einthoven introduces the term 'electrocardiogram'
1895 Einthoven distinguishes five deflections - P, Q, R, S and T
1902 Einthoven publishes the first electrocardiogram
1905 Einthoven starts transmitting electrocardiograms from the hospital to his laboratory 1.5 km away via telephone cable
Willem Einthoven
1924 the Nobel prize
1860- 1927
ECG gives information about:
Frequency (changes of HR in S A node or arrhythmias, sick sinus syndrome)
2. Conduction (blocks - SA, AV)
3. Rhythm (ES - supraventricular, ventricular)
4. Ventricular gradient (relationship between depolarization and
repolarization: origin - metabolic, hemodynamic, anatomic,
physical...ischemia, hypertrophy, dilatation, cardiomyopathy, inflammations,
changes in electrolytes, drugs...)
SA uzol
Myokard predsieni
AV uzol
Hisov zväzok
Tawarové ramienka
Purkyňové *~-L vlákna y
j Myokard komôr
EKG
[m s] 0
PQ interv.    QRS QT 0,16        0,1 0,3
- i_ !       HR - dependent
Atrial depol.       Ventricular complex
(depol.) (repol.)
F
Goldberger, 1947, aVR, aVL, aVF
HEXAAXIAL SYSTEM
aVF
I
aVR
WILSON
GOLDBERG
augmented
aVF
Frontal projection of vector!
Bipolar (I, II, III)
Unipolar (augmented) aVR, aVL, aVF
CHEST LEADS
PROJECTION PLANES OF CARDIAC VECTOR
AND ECG LEADS
E - Einthoven triangle
ELECTRICAL AXIS OF THE HEART
Summary of all momentary vectors, which form ventricular depolarisation loop. Expresses the direction of ventricular activation. Reflects asymmetry in ventricular wall thickness and the position of the heart in the chest.
ELECTRICAL AXIS - in the frontal plane
(R-Q-S)   in lead I., II., III.
triangle
LEFT DEVIATION, RIGHT DEVIATION
i -rvA_	I +
	\ \          7 111
i ~rc~y—	v+ 1 \ 1*-*'-. /
iii-rj\—	\  v / m
ARRHYTHMIA(S)
disturbance of impulse generation or
disturbance of impulse conduction
RESPIRATORY (SINUS) ARRHYTHMIA
1847, Ludwig, ECG and breathing of dog - respiratory sinus arrhythmia Detectable already during prenatal life.
Present in numerous species in animal kingdom - in all vertebrates.
Physiological meaning ???? STABILISATION OF MEAN BP (protection against mechanical effect of intrathoracic pressure on arterial BP)
Key effect of parasympathetic NS (decrease of its tonus), sympathetic NS only modulates!!!
MECHANISMS:
1) CENTRAL
2) REFLEXES FROM LUNGS
3) REFLEXES FROM BARORECEPTORS
4) REFLEXES FROM RECEPTORS IN THE RIGHT ATRIUM
5) LOCAL EFFECTS ON SA NODE
6) EFFECT OF OSCILLATIONS OF pH, pa02, paC02
ARRHYTHMIAS = disturbance of impulse generation or conduction
RHYTHM and FREQUENCY: Regular
1) Normal HR range: 70 - 220 bpm; effect of age)
2) Sinus tachycardia (60 - 100 bpm; exercise; aging)
3) Sinus bradycardia (below 60 bpm; athletes' heart)
4) Nodal rhythm - below 40 bpm, ventricular rhythm - below 20 bpm)
Irregular
1. sinus respiratory arrhythmia (physiological)
2. Sick sinus syndrome
3. Extrasystoles (ES) single or coupled (bigeminy, trigeminy), according to site or origin - sinus, atrial, junction, ventricular
BLOCKS
SICK SINUS SYNDROM AV BLOCKS
r
PQ>0.2sec
LBBB
II
O
RBBB
Wenckebach periods (phenomenon)
in
o
A-V dissociation
BUNDLE BRANCH BLOCK (BBB) - LEFT, RIGHT
REENTRY
Common mechanism of (paroxysmal) tachycardias, extrasystoles, bigeminy, etc.
• Double pathway Diverging and converging of excitation pathways
• Unidirectional block
1. Long refractory period
2. Slowed conduction
3. Reentry
1.
2.
Loops most often at the level of AV junction Determinants of re-entry:
Proper dimension of the loop Proper timing of the trigger ES
TACHYARYTHMIA
• SINUS TACHYCARDIA
• PAROXYSMAL TACHYCARDIA (supraventricular, ventricular)
• FLUTTER (>250/min; atrial)
• FIBRILLATION (>600/bpm; atrial, ventricular; breakdown of electrical homogeneity)
ATRIAL FLUTTER
Frequency 250 - 600/bpm Atrioventricular block n:l
ATRIAL FIBRILLATION
Irregular ventricular rhythm
+ f-waves
VENTRICULAR FIBRILLATION
oVR
VI
V2
V5
m
V3
V6
fiWTHM STRtPi fl 25 ami/mo; I cm/mY
COOOOtWJOOO -^
Frequency above 600/bpm, LETHAL
HEART ISCHEMIA
A: exercise angina pectoris
B: acute non-Q myocardial infarction
C: acute Q myocardial infarction