ECG to continue….

Interval changes assessment

PR (PQ) interval QT interval Normally .12 s - .20 s (that is 3 – 5 mm of horizontal distance) Shorter (e.g.) in preexcitation syndromes Longer (e.g.) in AV block of first degree Dependent of the frequency For 60 beats / s is around 0.45 s QT interval

Preexcitation syndromes Accessory signal pathway Orientation of QRS complex vector depends on the direction of propagation of the signal Sy Wolff-Parkinson-White has “delta” wave Sy Lown-Ganong-Levin (without “delta” wave) Risk of supraventricular paroxysmal tachycardia

type A type B

Reentry tachyarrythmias Reentry in Wolff-Parkinson-White’s Syndrome Accessory pathway Ectopic atrial extrasystole tachycardia wave Short PR

AV block 1-st degree: Long PR inteval 2-nd degree type one type two 3-rd degree: No connection between atria and ventriculi

AV block of 2-nd degree Wenkebach’s periods (Mobitz II)

AV block of 3-rd degree

Other causes of interval changes Short PR interval preexcitation sy, sympathetic act., hypoK, AV nodal rhythms from the beginning of it Long PR interval AV block 1-st degree parasympathetic act., hyperK, IHD, medicaments (e.g. beta blockers) Short QT interval Digitalis, hyperCa (hyperK – tall pointing T wave) Long QT hypertension, after MI hypoCa, (hypoK– U wave), Congenital (risk of sudden death)

QRS – left ventricular overload Sokolow’s index: R in (V5 or V6) + S inV1 > 35mm Attention young slim individuals (heart as a voltage source is closer to the chest leads – bigger voltage on the leads without hypertrophy) Left heart hypertrophy physiological

QRS – right ventricular overload Vertical electrical axis (> 100°) in V1: R >= 7mm or qR (volume overload) in avR: r > 4 mm in V6: R smaller/equal S (volume overload) Physiological Pressure overload Physiological Volume overload

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QRS - right BBB Causes: Dilatation and/or overload of right heart, MI, sometimes “physiological” QRS > 0,11 s If complete, then R’(r’) wave is bigger then R(r ) in V1 Repolarization changes

QRS – left BBB Causes: IHD, hypertension, cardiomyopathy, valvular disease, unknown QRS >0,11s (with complete block) Discordant T! and discordant dinivelization of ST

QRS – Q wave myocardial infarction In the Q-wave MI, there is necrosis throughout the cardiac wall, while in the non-Q wave, necrosis affects the endocardial zone only. Pathological Q-wave Appears in the first 0,04 s of QRS Appears in the leads where there should be no Q or overlays the normal R (r) (e.g. in V1 to V5) – absence of the R-wave Deeper then 2mm (6mm in III) Q > 0,25 R for I, II, avL, (avF) Q > 0,15 R forV1 to V6

QRS – Q wave MI There is no Q-wave in the beginning, but so-called “Pardee’s” wave (elevation of ST+ negative T) We imagine the (left) heart as pyramid to describe the MI location. Anterior Septal (right) Lateral (left) Inferior (down side at the apex) and it’s posterior extension (close to the base of the pyramid)

Combination of BBB and MI

QRS – serious embolism, fibrosis, hydropericardium

Beware – some changes are result of lead displacement