المحاضرة 23 الدقات الزائدة (خفقان القلب) خارج النظام Ectopic Beats

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ىئابرهكلا بلقلا مسر تاراهم ةرود

ECG Teacher

بلقلا تابرض للاتخإ

Arrhythmias

23

مقر ةرضاحم

ماظنلا جراخ )بلقلا ناقفخ( ةدئازلا تاقدلا

Ectopic Beats

ىبرعلا صخلملا :لاوأ

:

  ةماه طاقن

عئاش ريغ عون وه ينيذلأا بلقلا عر ا ست

بلقلاب ضارمأ نم نوناعي لا نمل ثدحي ام اًبلاغ

.  ةدومحم ريغ ضارعأ ىلإ يدؤي دق كلذ عمو اًمئاد ةديمحلا ضارملأا نم دعي

ةركبملا ةينيذلاا ةقدلا لاوأ

Premature Atrial Beat

روي يذراوب ةولأقن ىوق ةويكيتاموتوأ ةراورإ إودوح ووه اهداعيم لبق اركبم ىتأت ىتلا ةقدلا ببس

لقتنت اهدعبو اركبم ىنيذرا بالأقتسلإا ةلازإ إودحو يذرا ضابقنإ ىلإ ىدؤي امم

SA node

.

لكشلاب امك ةركبم ةقد ةردحم اضيأ ىنيلأبلا بالأقتسلإا ةلازإ لمكتل يلأبلا ىلإ

وولت لاووقتنإ رو

PAC

رووكبملا وأ ووضانلا رووي ىوونيذرا ضاووبقنلإا اووضيأ ووضولا اذووه ىمووسيو

وويك ةوعومجم ومز نوق

AV node

ةينيلأبلا ةينيذرا ةدقعلا قير لأ ع إدحي ةركبملا ةجوملا

ةريغص تاعبرم

3

م لقا ىأ ىعيبلألا مزلا وه س رآ

ةركبملا ةركبملا ةينيلأبلا ةقدلا :اينار

Premature Ventricular Beat

دوقو bizarre shaped

لاوعأ لكوشلاب ةزويممو يلأبلاوب ةويكيتاموتأ ةرؤوب وم وبنت ةقد ىهو

ةوجوملا لاوقتنإ ةعروس رلأبول ولذو ةريغوص تاعبرم

3

م رركأ سإ رآ يك ةعومجم انه وكت

P

ةووجوم ىوولع ىوولأغت اووهنأ ىووحلايو يوولأبلا لووخاد لووقنلا زاووهج ىووق اووهنع يوولأبلا يووسن لووخاد

اووم ةرووكبملا ةووينيلأبلا ةووقدلا ووبتيو توويقوتلا سووين ىووق إدووحت إوويح ىوونيذلاا ضاووبقنلإاب ةووصاخلا

.

compensatory pause

ىضيو عتلا فقوتلاب ىمسي

اهعبتي ةينيلأبلا وا ةينيذلاا راوس ةركبملا تاقدلا أ ىحلان ىلع أ ىلإ لكشلل انرىن اذإو

ةوقدلا ةولاح ىوق ىموس ت و رومحلاا مهوسلاس تاوجوملل ةويبرهكلا ةلأوشنرا فقوت م ةرتق

ةقدلا أ ىنعي ام وهو compensatory pause

ى ضيوعتلا فقوتلا ةركبملا ةينيلأبلا

.

SA node

ةدقع وأ ىساسلاا بلقلا ورتسيام ىلع ريرات ىأ اهل وكي ل ةركبملا

ةوينيذرا يتلاوحلا اوتلك ىوق اوهلبقو ةروكبملا ةوقدلا دوعب

R

تاوجوم يب ةقاسملا ا ىحلا

ةمىتنم ةينيلأبلاو

ةوصاخلا

P

ةوجوملا هيق اعقوتم اك ىذلا اكملا ىلإ ريشي ىلعا ىلإ لكشلا ىق رمحرا مهسلاو

ىنيذرا ضابقنلإاب

لدوعم نوق ةوينيذلاا ةرووبلا اوكم بوسح فولتخت

SA node

ةوينيذرا ةدوقعلل ىقاوعتلا ةرتق لاو

.ىلعلا لكشلاب امك قوتم ري وكيو ةركبملا ةقدلا دعبو لبق فلتخي بلقلا تابرض

ةدئازلا ةقدلا دعبو لبق فلتخي هنر مىتنم ري وكيس بلقلا تاقد لدعم أ ىأ

.

non compensatory

ىضيوعت ري تاجوملل ىبرهكلا لأاشنلا فقوتل ةيمستلاق بلألابو

دةق ةرةكبملا ةةقدلا نع ةلوئسملا

Atrial Ectopic Focus

نيذلأا لخاد ةطشنملا ةرؤبلا نلأو

ةهل ىئاةبرهكلا مةسرا ىةف ةةبولقم

P

ةةجوم نايحلأا ضعب ىف دجت فوسف ءزج ىأ ىف دجاوتت

AV node

ةةينيطبلا ةةيينيذلأا ةدةقعلا نةع دةعبلا بةسح ةريةرق نوةكت دةق رآ ىب ةفاسملاو ةقدلا

نيطبلل ىبرهكلا طاشنلا لقن نع ةلوئسملا

لأبارلا للاخ م ويدييلا دهاش : اينار

http://www.youtube.com/embed/YF4PWRTDYb0

ةرضاحملل ىزيلجنلإا صنلا : ارل ار

ECTOPIC BEATS

Even in a normal heart, the inherent automaticity of cardiac cells occasionally results in tissue outside the SA node discharging and depolarising the organ. This is the mechanism generating premature ectopic beats. On the ECG, a premature atrial ectopic or, as it is frequently referred to, a premature atrial contraction (PAC), occurs earlier than the next predicted sinus beat.

Also, as the ectopic discharge originates in the atrium, it must be transmitted into the ventricles by the AV node and, consequently, into the ventricular conducting system. Therefore, as the wave is transmitted at normal speed around the chambers by the conducting system, the qrs complex associated with an atrial ectopic is of normal duration (that is less than 3 small squares in width: <0.12s). In fact, the depolarisation wave from a focus situated anywhere above the physiological bifurcation of the bundle of His will enter both branches of the intraventricular conducting system. Consequently, the qrs complex associated with discharge from a focus situated anywhere in this region will be of normal duration. In contrast, if a premature ectopic originates from a focus within the ventricles, the current is transmitted, at least in part, outside the ventricular conducting system.

Depolarisation moves through myocardium 4 to 8 times more slowly than through conducting tissue. So, the characteristic of a ventricular ectopic is that the qrs complex is prolonged in duration, resulting in a broad qrs complex (equal to or greater than 3 small squares) on the readout. In a ventricular ectopic, the pattern of spread of depolarisation is highly abnormal producing a complex of bizarre shape. As the sequence of depolarisation is deranged, the pattern of repolarisation is also abnormal, manifesting as lack of concordance between the ectopic qrs complex and the associated T wave.

Both atrial and ventricular ectopics are followed by a pause before the next sinus discharge. There are however, important differences between the nature of this pause in these two situations. In the case of ventricular

ectopics, while retrograde transmission of depolarisation into the atria, via the AV node, can occur on occasion, it is an unusual event. A ventricular ectopic (aka premature ventricular contraction: PVC), therefore, is not usually associated with retrograde depolarisation of the structures of the atria, including the SA node.

The SA node continues to discharge at its own inherent rate 'oblivious' to events below the AV node. As the sinus node continues to discharge at its own regular rate, the next P wave, following the ectopic, will occur at a predictable time point, as a simple multiple of the previous P to P wave interval. In addition, the heart rate following the ventricular ectopic is the same as that preceding it. A pause with these characteristics following an ectopic is termed a compensatory pause.

In contrast to ventricular ectopics, discharge from an atrial ectopic will usually result in depolarisation of the cells of the SA node, temporarily suppressing their discharge. The SA node recovers its function after a pause of variable duration. As the duration of recovery is variable, the timing of the next P wave is not predictable.

The next sinus discharge does not occur at a simple multiple of the P to P wave interval preceding the ectopic. Premature depolarisation of the SA node, also has a broader effect on its function and may ‘re-set’ its inherent rate of spontaneous depolarisation leading to a different heart rate, either faster or slower, following the ectopic. A pause with these characteristics is termed a non-compensatory pause.

:ىلا تلا طبارلا ىلع لجوج مجرتم عجار كلضف نم ةمجرت ىلأ جايتحلإا لاح ىف

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