Basics&of&ECG&
11.11.2014&
11.11.2014&
Vr3 betwen V1 and Vr4 Vr4 in 5th intercostal space
Timing&
• ↑&
If&ECG&speed&is&&25mm/s&<&
divide&300&by&the&number&
of&boxes&to&have&a&&heart&rate&
If&it&is&50&mm/s÷&600..&
11.11.2014&
200 ms (25 mm/s)
40ms(25mm/s) ↓ 20ms (50mm/s)
100 ms (50mm/s)
P"wave"is"generated"by"ac1va1on"of"the"atria,"the"PR"segment"represents"the"dura1on"of"atrioventricular"(AV)"conduc1on,"the"QRS"complex"is"produced"by"ac1va1on"of"both"ventricles,"and"the"STCT"wave"reflects"ventricular"recovery."
11.11.2014&
An initial negative deflection is called the Q wave; the first positive wave is the R wave; and the first negative wave after a positive wave is the S wave. A second upright wave following an S wave is an R’ wave
Normal&ECG&
11.11.2014&
P&wave&Normal&atrial&acKvaKon&(sinus"rhythm"CSR)&projects&posi1ve"P"waves"in"
leads"I,"II,&in&V1"is"commonly"biphasic,&with&an&iniKal&posiKve&deflecKon&followed&by&a&negaKve&one.&Regular&SR&is&when&difference&
between&consecuKve&PP&interwals&is&<&120&ms.&Sinus"bardycardia:"SR"<50/min,"Sinus"tachycardia:"SR">"100/min.""
FluctuaKons&mediated&by&the&vagus&nerve&occur&phasically,&with&heart&
rate&increasing&during&inspiraKon&and&decreasing&during&expiraKon&
P"wave"dura1on"is"normally"<"120"msec"(in&the&lead&with&the&widest&P&wave).&The&litude&in&the&limb&leads&is&normally&<"0.25"mV"and&the&terminal&negaKve&deflecKon&in&the&right&precordial&leads&is&normally&
less&than&0.1&mV&in&depth.&&
11.11.2014&
11.11.2014&
AV&Nodal&rhythm&
&
Atrial&fluXer&(F<wave&
250&–&350/min)&
&
Atrial&fibrillaKon(&f<wave&
350<600/min)&
11.11.2014&
LA enlargement
RA elargement
Atrioventricular&Node&ConducKon&
and&the&PR&Segment&&
&
The&normal&PR&interval&measures&120&to&200&msec&in&
duraKon.&
The&PR&segment&is&the&temporal&bridge&between&atrial&
acKvaKon&and&ventricular&acKvaKon.&It&is&during&this&period&
that&acKvaKon&of&the&AV&node,&the&bundle&of&His,&the&
bundle&branches,&and&the&intraventricular&specialized&
conducKon&system&occurs.&
11.11.2014&
Atrioventricular&block&• I&ᴼ& &AV&conducKon&1:1,&PQ&interval&>&200&ms;&&
• II&ᴼ &¬&all&P&wawes&are&conducted&to&the&ventricle&
– Type&I&(Wenckebach&or&Mobitz&I)&gradual&extension&of&PQ&with&falling&out&QRS&aeer&the&
longest&PQ&interval&
– 2:1&block&– Type&&II&(Mobitz&II)&constant&AV&interval&with&falling&out&QRS&
– Advanced&AV&block&(3:1,&4:1….)&
III&ᴼ&complete&AV&block:&no&relaKon&between&P&
and&QRS,&P&rate&is&faster&than&the&QRS&rate&
&
11.11.2014&
Ventricular&AcKvaKon&and&the&QRS&Complex&An&iniKal&negaKve&deflecKon&is&called&the&Q"wave;"the"first"posi0ve"
wave"is"the"R"wave;"and&the&first&negaKve&wave&aeer&a&posiKve&wave&is&the&S"wave."A&second&upright&wave&following&an&S&wave&is&an&R’"wave"
QRS&complex&is&usually&characterized&by&consistent&progression&from&
an&rS&complex&in&the&right&precordial&leads&(V1,&V2)&to&a&qR&paXern&in&the&lee&precordial&leads&(V5,&V6)&
The&upper&normal&value&for&QRS&duraKon&is&<110"msec&measured&in&
the&lead&with&the&widest&QRS&duraKon.&
&
"
&
11.11.2014&
&
The&normal&mean&QRS&axis&in&adults&
lies&between&<30°rees&and&
+90°rees&
&
&
&
&
&
11.11.2014&
Axis of heart
Mean& QRS& axes&more& posiKve&
t h a n & + 9 0&
d e g r e e s&
represent& right&axis& devia-on,"and"those&more&
negaKve& than&
< 3 0& d e g r e e s&
represent& le1&axis& devia-on."Mean"axes"lying"between" >90"a n d " > 1 8 0"d e g r e e s" a r e&referred& to& as&
extreme& axis&devia-ons"
11.11.2014&
Axis of heart RIGHT
LEFT
EXTREME
QRS&litude&&
• lee&ventricular&hypertrophy&– R&in&aVL&>&11&mm&
– S&in&V1&+&R&in&V5&or&V6&≥&35&mm&
• Right&ventricular&hypertrophy&– R&in&V1&≥&7&mm&
– R&>&S&in&V1&
11.11.2014&
Wide"QRS"complex"(>120"ms)"
&
Right&Bundle&Branch&&
Block&&
RBBB&
&
11.11.2014&
Wide"QRS"complex"(>120"ms)"
&
LeeBundle&Branch&Block&&
LBBB&
11.11.2014&
Wide"QRS"complex"(>120"ms)&Pre<excitaKon:&
Wolf&
Parkinson&
White&
Syndrome&
(WPW)&
11.11.2014&
Wide"QRS"complex"(>120"ms)&
Ventricular&rhythms&
< Ventricular&extrasystoles&< Ventricular&rhythm&(<100/min)&
< Ventricular&tachyarhythmias&(>&100/min)&
11.11.2014&
A. Monomorfic&ventricular&&tachycardia&&
– 100&–&300&/min,&&
– ≥&3&QRS,&&– non&sustained&<&30&s,&&– sustained&≥&30&s&
B. Ventricular&fluXer:& &
&monomorphic,&HR&>300/min&
C. Polymorphic&ventricular&tachycardia,
& &polymorphic,&HR&<&300/
min&
D. Ventricular&fibrillaKon,& & &polymorphic,&HR&
>&300/min&11.11.2014&
11.11.2014&
Ventricular&Recovery&and&the&ST<T&Wave&
The&normal&ST<T&wave&begins&as&a&low<amplitude,&slowly&changing&wave&(the&ST"segment)"that"gradually"leads"to"a"larger&wave,&the&T"wave."Onset"of"the"ST>T"wave"is"the"junc0on,"or&J"point,"and"is"normally"at"or"near"the"isoelectric"baseline"of&the&ECG.&The&polarity&of&the&ST<T&wave&is&generally&the&same&as&the&net&polarity&of&the&
preceding&QRS&complex&(usually&upright&in&leads&I,&II,&aVl,&aVf,&and&V4&–&V6,&negaKve&
in&lead&aVr&and&variable&in&leads&III&and&V1&<&V3)&
THE&U&WAVE.&The&T&wave&may&be&followed&by&an&addiKonal&low<amplitude&wave&known&as&the&U"wave."This"late"repolarizaKon&wave,&usually&less&than&0.1&mV&in&
amplitude,&normally&has&the&same&polarity&as&the&preceding&T&wave&and&is&largest&in&
the&midprecordial&leads&and&at&slow&heart&rates.&Its&basis&in&cardiac&
electrophysiology&is&uncertain;&it&may&be&caused&by&repolarizaKon&of&the&Purkinje&
fibers.&
THE&QT&INTERVAL&measured&from&the&beginning&of&the&QRS&complex&to&the&end&of&the&
T&wave&in&the&lead&with&the&longest&interval.&It&includes&duraKon&of&ventricular&
acKvaKon&+&recovery&=&duraKon&of&the&ventricular&acKon&potenKal.&Its&duraKon&
decreases&as&heart&rate&increases.&Corrected&QT:&QTc&=&QT/(R&<&R)1/2&(BazeX&
formula)&.&Normal&QTc&ranges&from&300&ms&to&450ms&(male)&and&460&(female)&
11.11.2014&
STT&changes&in&ACS&(in&2&
consecuKve&leads)&• ST"depression:"– ≥&1&mm&
– V2,&V3&≥&0,5&mm&
• T"changes:"
– NegaKve&T&(>&1&mm)&when&QRS&is&posiKve&
– High&symetric&T&(limb&leads&T>&6mm,&precordial&leads&>&10&mm)&
– PseudonormalizaKon&T&
• ST"eleva1on:"– ≥&1&mm&
– V2,&V3:&≥&1,5&mm&women,&≥2,0&mm&men&≥&40&years,&≥2,5&men&<&40&years&
– V3R,&V4R,&V7,&V8,&V9&≥&0,5&mm&
• Patological"Q"(sign"of"necrosis):"Q&≥&30&ms&(long)&and&≥&1&mm&(deep)"
• Infarcted"wall"– Inferior:&II,&III,&aVF&– Anterior:&I,&aVL,&V2<V6&– Lateral:&I,&aVL,&V6&– Posterior/infero<basal:&V7<V9,&or&ST&segment&depression&in&V2,&V3&and&R>S&in&V1&
– RV:&V3R,&V4R&&
11.11.2014&
11.11.2014&
11.11.2014&
11.11.2014&
Thank&You&
11.11.2014&