Transcript Interval changes

ECG to continue….
Interval changes assessment
PR (PQ) interval
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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
QT interval
• Dependent of the frequency
• For 60 beats / s is around 0.45 s
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
physiological
Left heart
hypertrophy
• 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)
QRS – right ventricular overload
Physiological Pressure overload
Physiological Volume 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)
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 nonQ 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