ECG Flashcards
Which leads show : Septal view of the heart
V1 + V2
Which leads show lateral view of the heart?
I , AVL, V5, V6
Which leads show an anterior view of the heart?
V3, V4
Which leads show inferior view of the heart?
II, III and AVF
Which lead is at 0 degrees
I
Which lead is at 60 degrees?
II
Which lead is at +90 degrees?
AvF
Which lead is at +120 degrees?
III
Which lead is at -150 degrees?
aVR
ECG - 1 small square
1mm / 40 ms
ECG : 1 large square
0.5cm / 200 ms
How is the rate calculated?
QRS (over 10 secs) x 6 = HR Big squares between R-R / 300
What is the definition of sinus rhythm?
Action potential originated from the SA node
How is sinus rhythm seen on an ECG?
- P waves up right: Lead II
- Inverted P wavesin: Lead AVR
Each P waves looks the same in the same lead
What is normal cardiac axis?
- Lead II
- aVF
What is RAD in ECG?
- Lead III +
- aVF +
- aVR + (extreme axis dev)
What is LAD in ECG?
- aVF
- Lead I
What is the definiton of cardiac axis?
Overall direction of electrical activity in the heart
What are the causes of L. axis deviation?
*Left bundle branch block
*Inferior MI
*Physiological } minor LAD in obese people
What is the definition of the PR interval?
atrial depolarisation and contraction
What is the ECG range of PR interval?
- 120 - 200m/s
- 3-5 small squares
What is the defintion of WPW syndrome?
Accessory pathway allows for conduction of electrical impulses into the ventricle at a site other than the AV node.
What are the ECG features of WPW syndrome?
- Short P-R interval : <120 m/s, AV node usually delays impulse to allow the ventricles to complete contracting but this accessory pathway bypasses the AV node
- Delta wave ‘slurred upstroke’ of the QRS complex
What is first degree heart block/
What is T1 mobitz - 2nd degree heart block?
- progressive lengthening of PR interval,
- one non conducted P wave, next conducted beat has a shorter PR interval
What is 3rd degree Heart block? (3)
- No relationship between P wave and QRS complex Regular P waves
- none are conducted by the AVN
- Broad QRS - ectopic beats
What is the management of AV block?
- 1st degree HB and Mobitz type 1 - usually do not require treatment as long as the patient is assymtpmatic
- Mobitz type 2 and complete heart block (3rddegree) require permanent pacemaker
What is T2 mobitz - 2nd degree heart block?
R-R interval is constant
occasional non conducted P wave - in variable or set ration
What is the pathophysiology behind LBBB?
- Blocked L. bundle branch
- Heart depolarised from Right bundle branch to left
- Electrical activity travels from right to left
- Tall R waves in lateral leads } Leads 1, V5,V6
- Deep S waves in Right leads
What are the ECG features in LBBB?
- -Further deepn ’S’ wave in V1 } ‘W’
- -Further ‘R’ wave in V6} ‘M’
- T wave inversion in anterolateral leads and is 2nd to abnormal repolarisation
What is the pathophysiology of RBBB?
- Left ventricle is activated as normal, impulse travels equally down the left and right bundles with
- septum activated from left to right LV is activated as normal
- so early part of QRS complex correlation to septal depolarisation is unchanged
What are the ECG features in RBBB?
- V1 : RSR pattern ‘M’
- V4/V5 : ‘W’:
broad S wave in V6
Bifascicular block
RBBB + LAFB
R. Bundle branch block and left axis deviation
Bifascicular block
RBBB + LPFB
R. Bundle branch block and right axis deviation
What is the defintion of QT interval?
Ventricular depolarisation and ventricular depolarisation
Start of the QRS complex until the end of the T wave.
Definition of ST segement
normally flat as no electrical activity, ventricles are already depolarised
What is the function of the T wave?
- ventricular repolarisation, anything that affects depolarisation affects repolarisation
- Check ; Orientation (upright/inverted), height
- Normally inverted in - V2, II, III and AvF (inferior leads)
Where are T waves normally inverted?
Normally inverted in - V2, II, III and AvF (inferior leads)
What is the definition of Posterior STEMI?
Posterior STEMI - classically reciprocal changes in anterior leads
>ST depression in V1, V2, V3
> Tall, broad R waves (30 secs)
>Upright T waves