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&divide&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&amplitude&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.&&

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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 &&not&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&

&

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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.&

&

"

&

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&

The&normal&mean&QRS&axis&in&adults&

lies&between&<30&degrees&and&

+90&degrees&

&

&

&

&

&

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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&amplitude&&

•  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&

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Wide"QRS"complex"(>120"ms)"

&

Right&Bundle&Branch&&

Block&&

RBBB&

&

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Wide"QRS"complex"(>120"ms)"

&

LeeBundle&Branch&Block&&

LBBB&

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Wide"QRS"complex"(>120"ms)&Pre<excitaKon:&

Wolf&

Parkinson&

White&

Syndrome&

(WPW)&

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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&&

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11.11.2014&

Thank&You&

11.11.2014&