ecg Flashcards
what is an ecg
- Representa electrical events of cardiac cycle detected by placing electrodes on the surface of the body
- Summation of electrical activity
what are the 3 basic laws on ECG
- A positive complex is formed in depolarisation, when the lead is in the direction of flow
- A negative complex is formed in repolarisation, when the lead is against the direction of flow
- If the lead is at 90 degrees to the wave
of depolarisation, then you get a biphasic waveform.
The initial part is if it goes towards the lead
and then goes away from the lead.
what is the difference between bipolar leeds adn unipolar leeds
*Bipolar leads measures from two points on the actual surface
* 1 lead on th body with a virtual reference point with 0 electrical potential located in centre of heart
what are the 12 leads of a standard ECG
- 3 bipolar: I,II,III
- 3 Augmented unipolar: AVR, AVL, AVF
- 6 Unipolar precordial leads
what is the direcion of bipolar lead 1
- R arm to L arm
- depol will be positive
- repol will be negative
what is the direction of bipolar lead II
- right arm to Left leg
- positive deflection in both the P waves and the QRS
complexes
what is the direction of biploar lead III
- Left arm to Left leg
what are the plasments of the augmented unipolar leads: AVR, AVL, AVF
- AVR = right shoulder
- AVL = left shoulder
- AVF = over pubic symph
Hexaxial reference system I - 0 degrees
II - __ degrees
III - ___ degrees
aVR - ___ degrees
aVL - ___ degrees
aVF - ____degrees
II - 60 degrees
III - 120 degrees
aVR - 210 degrees
aVL - 30 degrees
aVF - 90 degrees
what do V1 and V2 leads look at
left ventricle + left inter ventricular septum septum
what do v3 and v4 leads look at
anteroir wall
what are v5 and v6 looking at
lateral wall
what is the P wave
Atrial depol from SA node
what is QRS complex
- Ventricular depol at apex of heart
- Atrial repol
what is the T wave
Ventricular repol
P waves are always __ in leads I and II
a)+ve
b)-ve
a
P wave are always __ in AVR lead
a) +ve
b)-ve
b
how many mm per second
25
how many mm is 1 mV
10mm
In a normal electrocardiogram (ECG), the PR interval should typically fall within which of the following ranges?
A) 0.12 to 0.20 seconds
B) 0.20 to 0.30 seconds
C) 1.0 to 1.5 seconds
D) 2.0 to 2.5 seconds
a
what is a long PR interval indicitive of
1st degree heart block
a noral T wave is
a) symetrical
b) asymetrical
b
in a normal ECG how do you calc HR
300/ big squares between R-R complex
Width of deflection reflects speed of ________
conduction
Positive deflection is towards the _______
lead/vector
what would cause a PR interval to be shorter
in younger patients or in Wolf-Parkinson-White syndrome
what does a broad QRS complex indicate
- Ventricular conduction delay / bundle branch block
- Pre-excitation
what does a small QRS complex inidicate
- Obese patient
- Pericardial effusion
- Infiltrative cardiac disease
The P waves should be upright and there should be no Q waves or only a small in which leads
- I
- II
- V2
- V6
All waves are negative in lead ___
AVR
how can Hyperkalaemia present on an ECG
- Tall T waves
- flattenied P waves
- broad QRS
- eventually ‘sine wave pattern’
how can Hypokalaemia present on an ecg
- Flattened T wave
- QT prolonged
how can Hypercalcaemia present on an ECG
QT shortening
how can Hypocalcaemia present on an ECG
- QT prolongation
what could a low amplitude p wave indicate
Atrial fibrosis
Obesity
Hyperkalaemia
what could a broad and bifid P wave indicate
Left atrial enlargement
what could a high amplite p wave indicate
atrial enlargments
what could a tall QRS complex indicate
left ventricular hypertrophy
T wave is usually inverted in which leads
aVR and can be in III
The R wave must grow from V_ to atleast V_
1 to 4
what are ectopic beats
- Very Common
- Non sustained beats arising from ectopic regions of atria or ventricles
- Generally benign
- High burden VE can cause heart failure
- High burden AE can progress to AF
Male with chadsvasc score of one, would you treat and what with
yes anticoag (warfarin/doac)
female with chadsvasc score of 1 would you treat
no
what shape in the ecg does a right bundle block make
M QRS complex
acronym MaRRow
what shape in the ECG does a left bundle block make
W QRS
acronym WILLiam
what are some possible conditions for black outs
Conduction disease/bradycardia/ Extreme tachycardia
what are some possible conditions for chest pain
pericarditis, MI
