ECG Interpretation Made Easy (Learn How to Interpret an ECG in 13 Minutes)

00:13:07
https://www.youtube.com/watch?v=u1m3HKW1VqU

Summary

TLDRCette vidéo propose une approche systématique pour lire un électrocardiogramme (ECG) de façon plus confiante, en expliquant comment chaque composant de l'ECG reflète l'activité électrique du cœur à différents moments du cycle cardiaque. L'importance de vérifier les informations du patient, la date, et la calibration avant l'interprétation est soulignée. On enseigne à évaluer l'axe cardiaque, le rythme et la fréquence avec une attention sur les complexes QRS, les ondes P, et l'intervalle PR. La morphologie des ondes, comme le complexe QRS et les segments ST, est interprétée pour diagnostiquer d'éventuelles anomalies ou maladies cardiaques.

Takeaways

  • 📚 Une approche systématique améliore la lecture d'un ECG.
  • ⚡ Chaque élément de l'ECG reflète l'activité électrique cardiaque.
  • 🕒 Vérifiez l'information du patient et la calibration d'ECG avant de commencer.
  • 🔍 L'axe cardiaque se déduit facilement avec la méthode des quadrants.
  • 💓 Évaluez le rythme en fonction de l'intervalle RR.
  • 🔄 Différents complexes QRS aident à identifier des origines supraventriculaires ou ventriculaires.
  • ❌ Des anomalies dans les ondes P peuvent indiquer une dilatation auriculaire.
  • 📏 L'intervalle PR fournit des indices sur la conduction entre les oreillettes et les ventricules.
  • 🩺 Les segments ST anormaux peuvent signaler une ischémie cardiaque.
  • 💡 Tenez compte de l'évolution des ECG dans le temps pour un diagnostic complet.

Timeline

  • 00:00:00 - 00:05:00

    Le premier extrait vidéo explique les bases de l'interprétation de l'électrocardiogramme (ECG), une compétence souvent négligée en médecine. Il introduce les composants de l'ECG qui représentent l'activité électrique cardiaque, associés aux points du cycle cardiaque. Par exemple, l'onde P montre la dépolarisation atriale. Un ECG standard utilise quatre électrodes sur les membres et six sur le torse, chaque électrode donnant une vue différente du cœur. La vidéo aborde ensuite les informations essentielles à vérifier avant l'interprétation, comme les informations du patient, la date et l'étalonnage de la machine. L'étape suivante consiste à analyser l'axe électrique, en utilisant une méthode quadrante avec les dérivations 1 et avF pour évaluer l'axe en vue de détecter des anomalies potentielles précocement.

  • 00:05:00 - 00:13:07

    Le deuxième extrait continue l'analyse de l'ECG en évaluant la fréquence cardiaque et le rythme. La fréquence cardiaque est évaluée en utilisant un raccourci pour calculer le taux ventriculaire, et on distingue bradycardie et tachycardie selon les battements par minute. Le rythme est vérifié en examinant l'intervalle RR pour voir s'il est régulier ou irrégulier. L'extrait se penche également sur l'évaluation du rythme atrial en vérifiant l'onde P et l'intervalle PR, qui montre le temps entre la dépolarisation atriale et ventriculaire. Des anomalies peuvent signaler diverses pathologies, comme la fibrillation atriale ou les blocs AV. Enfin, l'extrait aborde la morphologie du complexe QRS et ses implications cliniques, comme la différence entre battements supraventriculaires et ventriculaires, et l'identification des blocs de branches.

Mind Map

Video Q&A

  • Quelle est la durée normale de l'intervalle PR ?

    L'intervalle PR normal se situe entre 120 et 200 millisecondes.

  • Quel est le raccourci pour estimer la fréquence cardiaque à partir d'un ECG ?

    Divisez 300 par le nombre de grands carrés entre chaque complexe QRS pour obtenir la fréquence ventriculaire approximative.

  • Quels segments de l'électrocardiogramme indiquent une activité auriculaire ?

    L'onde P représente la dépolarisation auriculaire.

  • Comment identifier une déviation de l'axe sur un ECG ?

    La méthode des quadrants est utilisée, en regardant les dérivations 1 et avF. Si les deux sont positives, l'axe est normal.

  • À quoi ressemble une onde T négative ?

    Une onde T négative est connue comme une inversion d'onde T. Elle est normale en V1, aVR et dérivation 3.

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  • 00:00:00
    foreign
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    [Music]
  • 00:00:05
    of an electrocardiogram known as an ECG
  • 00:00:08
    or EKG is a skill in medicine that is
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    often overlooked in this video I'll
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    provide a systematic approach to help
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    you read them more confidently
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    the basics to remember are that each
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    component of the ECG represents
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    electrical activity within the heart
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    corresponding to different points in the
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    cardiac cycle for example the P wave
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    represents atrial depolarization and we
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    will look at each of these points in
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    more detail as part of the
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    interpretation
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    a normal 12 lead ECG is taken by using
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    four limb electrodes and six chest
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    electrodes each lead gives a slightly
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    different view of the heart with a
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    positive deflection when the activity is
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    towards that electrode and negative when
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    it is away from it leads 1 AVL V5 and V6
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    look at the lateral part of the heart
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    2 3 and avf the inferior part and V1 to
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    V4 give a septal and anterior View
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    the first step is to ensure the correct
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    patient information the date and the
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    calibration of the machine the date and
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    time are especially important because
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    you may be looking at one of a series of
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    ECGs looking for changes over time the
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    calibration is normally 25 millimeters
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    per second and 10 millimeters per
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    millivolt if these settings are adjusted
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    before the ECG is taken it can look
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    completely different so you need to
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    check it before you start interpreting
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    once they are confirmed I start by
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    looking at the axis because it is so
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    easy to overlook the overall direction
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    of the electrical activity gives the
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    axis and is normally between -30 and 90
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    degrees it could be normal deviated to
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    the left or to the right or extremely
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    deviated a quick way to assess it is the
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    quadrant method that allows you to
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    quickly place the axis in one of the
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    four quad just by looking at Lead 1 and
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    avf if both the positive the axis must
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    be in the lower right quadrant therefore
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    normal if Lead 1 is negative and avf is
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    positive there is right access deviation
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    if both the negative there is Extreme
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    axis deviation
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    the only one needing a further step is
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    if Lead 1 is positive and avf is
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    negative then the axis is in the upper
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    right quadrant and to distinguish left
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    axis deviation from normal you can look
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    at lead two if it is negative the axis
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    is deviated to the left
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    axis deviation can occur in many
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    different conditions and is not specific
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    but looking at it first can alert you
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    early that there could be further
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    abnormalities
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    next we look at the rate each small
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    square is one millimeter in width on the
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    standard speed of 25 millimeters per
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    second the small squares on the paper
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    represent 40 milliseconds and five of
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    these together form bigger squares
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    therefore with 200 milliseconds each
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    that means five of these big squares
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    make up one second so if one beat
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    happens every five big squares that's
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    one beat in one second so 60 beats in a
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    minute a shortcut is to divide 300 by
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    the number of large squares between each
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    QRS to get the approximate ventricular
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    rate this is easy if the rhythm is
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    regular if it's not then instead count
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    the number of QRS complexes over 10
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    seconds then multiply it by 6 forget the
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    number of beats in one minute
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    the normal rate is 60 to 100 beats per
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    minute with rates below that being
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    called bradycardia and above that being
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    tachycardia
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    that brings us nicely to Rhythm which
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    basically means do the Beats fall at
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    regular intervals to evaluate this look
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    at the gap between the QRS complexes
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    known as the RR interval is it the same
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    size each time or does it change this is
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    more obvious at normal heart rates but
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    can be tricky to distinguish at very low
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    or very high heart rates if the gap
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    between beats changes throughout the ECG
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    then the rhythm is irregular but the
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    story doesn't end there the irregularity
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    can be present with no clear pattern
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    known as irregularly irregular like
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    atrial fibrillation or regularly
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    irregular such as in some second-degree
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    heart blocks
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    looking at the QRS complexes evaluates
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    the ventricular Rhythm but it's also
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    important to evaluate the atrial rate
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    and the communication between the Atria
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    and the ventricles which is why I also
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    include the P wave and PR interval when
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    looking at the Rhythm
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    the P wave represents atrial
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    depolarization
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    the normal P wave should be positive in
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    lead 2 have a duration of less than 120
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    milliseconds an amplitude of less than
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    2.5 millimeters and each P wave should
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    be followed by a QRS complex
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    some abnormalities can include an
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    increased duration or amplitude of the P
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    wave that may indicate left or right
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    atrial dilatation respectively or the
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    absence of p waves entirely such as in
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    atrial fibrillation
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    the electrical activity then normally
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    passes through the Atria ventricular
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    node just before being conducted down
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    into the ventricles and causing
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    ventricular depolarization and
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    contraction the PR interval is the time
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    between atrial depolarization and
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    ventricular depolarization and is
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    measured from the start of the P wave to
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    the start of the QRS complex its normal
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    duration is between 120 and 200
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    milliseconds a prolongation indicates
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    slowing of the conduction between the
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    Atria and ventricles for example a first
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    degree AV block a shortening may suggest
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    a condition with an accessory pathway
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    like wolf Parkinson White
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    a variable PR interval suggests other
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    forms of atrioventricular blocks I'll
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    leave a link to a video dedicated to
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    Heart blocks here
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    next up is the morphology of the
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    remaining components of the ECG there is
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    the QRS complex itself which represents
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    ventricular depolarization and is
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    generally divided into narrow or widened
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    normally the electrical activity moves
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    quickly through the conduction system
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    and goes more slowly through the muscle
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    tissue narrow complexes generally
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    suggest the origin of that beat is
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    supraventricular while a wider QRS
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    suggests either the activity is
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    originating in the ventricles or there
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    is a block in the conduction system
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    carrying the electrical signal to one of
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    the ventricles and so to get to the
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    other side must go through The
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    myocardium the latter is why left and
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    right bundle branch blocks have a wide
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    QRS morphology and pacemakers will also
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    traditionally have a morphology similar
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    to left bundle branch block
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    here is a comparison of left and right
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    bundle branch blocks and an easy way to
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    remember the morphology of each is the
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    mnemonic William marrow the voltage of
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    the QRS complexes can also indicate
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    pathology classically large amplitudes
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    in the precordial leads May point to
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    left ventricular hypertrophy while
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    alternating amplitudes could indicate
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    pericardial effusion
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    Q waves are the first negative
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    deflection in the QRS the r wave is a
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    following upwards deflection and S is
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    any negative deflection following that
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    pathological Q waves are defined as Q
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    waves greater than 25 percent of the QRS
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    complex with a width greater than 40
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    milliseconds they can indicate previous
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    ischemia there should be progression
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    from V1 to V6 where the S Wave is
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    initially greater than the r wave but
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    then at around V3 or V4 the r wave
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    becomes greater than the S Wave
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    poor progression can also indicate
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    previous ischemia
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    the ST segment is next representing the
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    interval between ventricular
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    depolarization and repolarization it
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    extends from the end of the S Wave to
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    the start of the T wave this is a famous
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    part of the ECG as elevation of this
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    segment May indicate an st elevation
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    myocardial infarction as well as other
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    conditions like pericarditis in cases of
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    St elevation it's important to look for
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    reciprocal changes in opposite leads for
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    example St elevation in anterior or
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    lateral leads may have reciprocal St
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    depressions in the inferior leads
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    depressions of this portion generally is
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    an abnormal finding that can also
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    indicate ischemia it's worth noting that
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    it's difficult to interpret the ST
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    segment in people with bundle branch
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    blocks therefore more specific criteria
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    are needed
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    another feature to be aware of is the
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    jpoint which is where the S wave ends
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    and the ST segment begins as it can be
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    raised causing the appearance of St
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    elevation this is also known as benign
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    early repolarization and tends to happen
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    in people under the age of 60. it's also
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    likely to be present in multiple leads
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    not corresponding to a specific
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    territory and will not have reciprocal
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    changes and will not change over time as
  • 00:10:07
    you would expect with acute ischemia
  • 00:10:09
    T waves indicate repolarization of the
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    ventricles and can be described as tall
  • 00:10:14
    flat inverted or even biphasic in most
  • 00:10:18
    cases they will be positive and
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    concordant with the QRS complex but in
  • 00:10:23
    cases where they are negative they are
  • 00:10:25
    known as t-wave inversions this is
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    normal in V1 AVR and Lead 3 and can also
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    persist from childhood in some people in
  • 00:10:34
    V2 and V3 inverted T waves in the
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    absence of St changes can indicate a
  • 00:10:41
    historic ischemic event
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    the classic example of tall T waves is
  • 00:10:45
    hyperkalemia and biphasic T waves
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    meaning T waves that have both a
  • 00:10:50
    positive and negative components are
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    usually due to ischemia or hypokalemia
  • 00:10:57
    the interval between the start of the Q
  • 00:10:59
    wave and the end of the T wave is the QT
  • 00:11:02
    interval and it represents the time
  • 00:11:04
    taken from the start of ventricular
  • 00:11:07
    depolarization to the end of
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    repolarization
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    it gets shorter with faster heart rates
  • 00:11:13
    and longer with slower heart rates so it
  • 00:11:16
    needs to be corrected for the heart rate
  • 00:11:18
    for interpretation classically this is
  • 00:11:21
    using bezet's formula its normal value
  • 00:11:24
    is generally above 360 milliseconds and
  • 00:11:27
    less than 440 milliseconds in males or
  • 00:11:31
    less than 460 milliseconds in females
  • 00:11:33
    it's important to remember this as
  • 00:11:36
    prolongation can predispose to
  • 00:11:38
    potentially lethal arrhythmias like
  • 00:11:40
    ventricular tachycardia or torsads
  • 00:11:43
    U waves are other waves that
  • 00:11:46
    occasionally appear after the T waves
  • 00:11:48
    most commonly as a result of electrolyte
  • 00:11:51
    imbalances or hypothermia using all of
  • 00:11:54
    this information you can categorize the
  • 00:11:56
    ECG tachycardia is generally divided
  • 00:12:00
    into broad or narrow complex and then
  • 00:12:02
    further into regular or irregular
  • 00:12:04
    bradycardia can be divided based on the
  • 00:12:07
    presence or absence of p waves then
  • 00:12:09
    further into if every P wave is followed
  • 00:12:12
    by a QRS complex or not this is not an
  • 00:12:15
    exhaustive list but covers some general
  • 00:12:17
    arrhythmias
  • 00:12:18
    overall the ACG is a snapshot of the
  • 00:12:22
    activity of the heart at the time it was
  • 00:12:24
    captured therefore it needs to be
  • 00:12:26
    correlated with the history of how the
  • 00:12:28
    patient presented and why the ECG was
  • 00:12:31
    indicated in the first place you also
  • 00:12:33
    need to consider changes over time for
  • 00:12:36
    example in myocardial ischemia another
  • 00:12:39
    good example is syncope or palpitations
  • 00:12:41
    due to an arrhythmia unless the
  • 00:12:44
    patient's heart was in an arrhythmia at
  • 00:12:46
    the time of the ECG it won't necessarily
  • 00:12:49
    be seen therefore longer monitoring with
  • 00:12:52
    a halter monitor may be used for further
  • 00:12:55
    reading and practice I would recommend
  • 00:12:57
    using the Life in the Fast Lane website
  • 00:12:59
    which is the main reference for this
  • 00:13:01
    video as they have a comprehensive
  • 00:13:03
    resource to improve your ECG reading
  • 00:13:06
    skills
Tags
  • Electrocardiogramme
  • ECG
  • Axe cardiaque
  • Complexes QRS
  • Onde P
  • Rythme cardiaque
  • Fréquence cardiaque
  • Intervalle PR
  • Onde T
  • Segment ST