ECG Flashcards
You should always look at an ECG within the clinical context of the patient. T/F?
True
Describe a systematic approach to an ECG
Assess if electrical activity is occuring
Assess heart rate and rhythm
Determine QRS axis
Assess P waves (presence, rhythm and morphology)
Check P-R interval
Assess width. and morphology of QRS complex
Look at ST segment
Assess morphology of T wave
How can heart rate be determined from an ECG is there is a regular rhythm?
300 / number of large squares between each QRS complex
How can heart rate be determined from an ECG is there is an irregular rhythm?
Number of QRS complexes present in rhythm strip x 6
What is the normal size of the PR interval?
<200ms / one large square
What is the normal width of the QRS complex?
<120ms or 3 small squares
What is the normal length of the QT. interval?
<440ms or 11 small squares
QRS complexes will be broad in normal sinus rhythm. T/F?
False - they will be narrow (<120ms)
In complete AV block what is the relationship between P and QRS waves?
No relationship - P waves appear to be occurring randomly
What is the relationship. between P and QRS wave in second degree AV block?
1:1 or 2 2:1
Describe the appearance of second degree AV block on ECG
Normal or slow heart rate Irregular rhythm Narrow QRS P waves present 1:1 or 2:1 for P:QRS
Describe the appearance of left bundle branch block on ECG
Broad QRS
Dominant S wave in V1
Dominant R wave in V6
In what direction does the ventricle depolarise in left bundle branch block?
From right ventricle to left
In what direction does the ventricle depolarise in right bundle branch block?
From left to right
Describe the appearance of right bundle branch block on ECG
r wave and deep S in V1
q wave and tall R in V6
P waves are absent in supraventircular tachycardia. T/F?
True
What is the heart rate in supra ventricular tachycardia?
Fast
What is the heart rhythm is. supra ventricular tachycardia?
Regular
There are no waves so the relationship between P and QRS waves cannot be assessed in supra ventricular tachycardia. How can the. AV node be blocked in order to assess the activity of the atrium?
Adenosine
What is the relationship between P and QRS waves in regular broad complex tachycardia?
Cannot be assessed as there are no P waves present
What are the differential diagnoses of regular broad complex tachycardia?
Ventricular tachycardia
Supraventricular tachycardia with BBB
Supraventricular tachycardia conducted over. an AP
Ventricular pacing
The normal P wave is positive in which leads?
Inferior leads
The normal T wave has the opposite polarity to the QRS complex. T/F?
False - it has the same polarity as the QRS complex
