A first look at the ECG Flashcards
what does a P wave represent in a normal ECG?
it represents atrial depolarisation
what precedes the QRS-complex?
the P wave
what does the P wave look like?
it looks like a small bump upwards from the baseline
what is the amplitude of a P wave in a normal ECG?
the amplitude is normally 0.05-0.25mV
what is the QRS-complex in a normal ECG?
it is a name for the combination of 3 of the graphical deflections seems on a typical ECG
where is the QRS-complex on a normal ECG?
it is usually the central and most visually obvious part of the tracing on the ECG
what does the QRS-complex correspond to?
it corresponds to the depolarisation of the right and left ventricle of the human heart
what is the normal duration of the QRS-complex?
the normal duration is between 0.08 and 0.1 seconds
what is considered an abnormal QRS-complex?
a QRS-complex duration of greater than 0.12 seconds
what does the T wave in a normal ECG represent?
it represents the depolarisation of the ventricles
what is referred to as the absolute refractory period?
the interval from the beginning of the QRS-complex to the apex of the T wave
what is the PR interval?
in an ECG, the PR interval is the period, measured in milliseconds, that extends from the bringing of the P wave until the beginning of the QRS-complex
what does the PR interval represent?
this interval represents the time between the onset of atrial depolarisation and the onset of ventricular depolarisation
what does the P wave in an ECG represent?
it represents the onset of arterial depolarisation
what does the PR interval correspond to?
it corresponds to the time lag from the onset of atrial depolarisation, this time lag allows atrial systole to occur, filling the ventricles before ventricular systole
what is the normal range for the PR interval?
it is normally between 120 and 200ms in duration
what is the normal range for the QRS-complex?
duration less than or equal to 0.12 seconds
amplitude greater than 0.5mV in at least one standard lead
amplitude greater than 1mV in at least on precordial lead
upper limit of normal amplitude is 2.5-3mV
what is the normal range for the QT interval?
the QT interval varies depending on age and gender, but it is usually 0.36 to 0.44 seconds
how is heart rate measured from an ECG?
count the number of RR intervals between 2 tick marks in the rhythm strip and multiply by 10 to get the beats per minute
define normal sinus rhythm
it is the characteristic rhythm of the healthy human heart
what is normal sinus rhythm?
it is the rhythm that originates in the sinus node
what is the heart rate like in regards to normal sinus rhythm?
the rate is generally regular but will vary depending on autonomic inputs into the sinus node
what does sinus rhythm mean?
it means a normal heart beat, both with respect to the heart rate and rhythm
what is normal heart rate?
a heart rate that will fall between 60 and 100 beats per minute
define normal sinus tachycardia
a sinus rhythm with an elevated rate of impulses
what is normal sinus tachycardia defined as?
a heart rate greater than 100 beats per minute in an average adult
define normal sinus bradycardia
sinus rhythm with a rate that is lower than normal
what is normal sinus bradycardia generally defined as ?
it is generally defined to be a heart rate of under 60 beats per minute
