lOMoARcPSD|26582732
Cardiology module 2025
True false: temporal change is more significant than constant isolated findings -
True
Time length of one large box -
0.2 seconds
Time length of one small box -
0.04 seconds
Voltage measured in one small box lenght -
0.1 mv
Voltage measured in one large box length -
0.5 mv
V lead placement -
V1- fourth intercostal space to the right of stermun
V2- 4th intercostal space to the left of sternum
V3- inf.lateral to V2
V4- 5th intercostal mid-clavicular line
V5- ant. Axilary line
V6- mid-axilary line
Two thumbs up sign -
+ lead I & + AVF
There is no deviation in the axis of the current
Left thumb = Lead 1 Right
thumb = AVF
Isoelectric line -
Imaginary line that establishes the base of an EKG and helps in distinguishing positive ,
negative or equaphasic voltage patterns.
Second glance -
In the case of a suspected Left axis deviation
Look at lead II : positive voltage= normal axis , Negative
voltage = left axis deviation
Equaphasic rule -
Find the most equaphasic leads among the Limb leads and Leads I, II, III. Then draw a
perpendicular line to that lead to find your flow of current.
Downloaded by NELSON KIIRU ()
, lOMoARcPSD|26582732
NO mans Land -
Both Lead I and AVF are negative
Causes: emphysema hyperkalemia lead
transposition ventricular tachycardia artificial
cardiac pacing
Causes of right axis deviations -
Normal in children and tall thin adults
Right ventricular hypertrophy
Chronic lung disease even without pulmonary hypertension ( there is back flow of the right
ventricle) anterolateral myocardial infarction left posterior hemiblock pulmonary embolus
Wolff-Parkinson-White syndrome - left sided accessory pathway
atrial septal defect ventricular septal defect
Causes of left axis deviation -
left anterior hemiblock
Q waves of inferior myocardial infarction
Artificial cardiac pacing
emphysema
hyperkalaemia
Wolff-Parkinson-White syndrome - right sided accessory pathway
tricuspid atresia
Ostium primum ASD
Injection of contrast into left coronary artery note: left
ventricular hypertrophy is not a cause left axis deviation
P wave -
Represents depolarization of atrial myocardium
Should always be paired with a QRS wave
Should be under 3 little boxes wide and 3mm in height.
Should all look alike an abnormally high P wave
= atrial enlargement
PR - interval -
Measured from the beginning of the P wave to the Beginning of the QRS complex.
Regular with is 0.12-0.20 seconds Should not be longer than one large box
If less than 3 small boxes --> accessory pathways from A to V
If longer = 1st degree AV block Lead II is used to measure it.
QRS complex -
Represents depolarization of the ventricular myocardium
Although termed the "QRS" complex, many complexes do not contain all three waves. These can be
polymorphic or monomorphic.
Downloaded by NELSON KIIRU ()
, lOMoARcPSD|26582732
0.07-0.11 sec in width. QRS widths often vary in different leads
Best leads to look at are usually leads I and V1
QRS should be narrow, the wider the complex the more likley the rythm is ventricular in origen
R prime -
A second R wave in a QRS complex
Best leads to look at a QRS complex -
Lead I, and V1
Low QRS height -
Defined as < 5 mm peak-to-peak in all limb leads or <10 mm in precordial leads
Chronic causes — pulmonary disease, hypothyroidism, obesity, cardiomyopathy
Acute causes — pleural and/or pericardial effusions
Q waves -
Negative deflection preceding the R wave
present only in leads I, AVL, v5, v6 normal Large Q
waves represent myocardial damage
ST segment -
Starts at J point( end of QRS complex) and ends at the beginning of the T wave.
ST segments should be flat in nature
Clinical importance is more based on its level more than length.
ST elevation: is significant for MI ST
depression = MI is eminant slide 40
EKG 1
QT interval -
Measurement of refractory period in which the myocardium would not react to an electrical
impulse. Starting from the beginning of the QRS to the end of the T wave.
Bassets formula -
Qt interval/ rr intervals squared
calculate heart rate
T wave -
Re-polarization of the ventricles
Should have the same polarity as QRS complex
T Waves are very fickle and can be altered by various things
Hyperkalemia can lead to consistently high peaked T waves.
Rand high peaks could be due to ischemic changes
U Wave -
Shallow gentle wave following the T wave
(forget about these for now)
Downloaded by NELSON KIIRU ()
Cardiology module 2025
True false: temporal change is more significant than constant isolated findings -
True
Time length of one large box -
0.2 seconds
Time length of one small box -
0.04 seconds
Voltage measured in one small box lenght -
0.1 mv
Voltage measured in one large box length -
0.5 mv
V lead placement -
V1- fourth intercostal space to the right of stermun
V2- 4th intercostal space to the left of sternum
V3- inf.lateral to V2
V4- 5th intercostal mid-clavicular line
V5- ant. Axilary line
V6- mid-axilary line
Two thumbs up sign -
+ lead I & + AVF
There is no deviation in the axis of the current
Left thumb = Lead 1 Right
thumb = AVF
Isoelectric line -
Imaginary line that establishes the base of an EKG and helps in distinguishing positive ,
negative or equaphasic voltage patterns.
Second glance -
In the case of a suspected Left axis deviation
Look at lead II : positive voltage= normal axis , Negative
voltage = left axis deviation
Equaphasic rule -
Find the most equaphasic leads among the Limb leads and Leads I, II, III. Then draw a
perpendicular line to that lead to find your flow of current.
Downloaded by NELSON KIIRU ()
, lOMoARcPSD|26582732
NO mans Land -
Both Lead I and AVF are negative
Causes: emphysema hyperkalemia lead
transposition ventricular tachycardia artificial
cardiac pacing
Causes of right axis deviations -
Normal in children and tall thin adults
Right ventricular hypertrophy
Chronic lung disease even without pulmonary hypertension ( there is back flow of the right
ventricle) anterolateral myocardial infarction left posterior hemiblock pulmonary embolus
Wolff-Parkinson-White syndrome - left sided accessory pathway
atrial septal defect ventricular septal defect
Causes of left axis deviation -
left anterior hemiblock
Q waves of inferior myocardial infarction
Artificial cardiac pacing
emphysema
hyperkalaemia
Wolff-Parkinson-White syndrome - right sided accessory pathway
tricuspid atresia
Ostium primum ASD
Injection of contrast into left coronary artery note: left
ventricular hypertrophy is not a cause left axis deviation
P wave -
Represents depolarization of atrial myocardium
Should always be paired with a QRS wave
Should be under 3 little boxes wide and 3mm in height.
Should all look alike an abnormally high P wave
= atrial enlargement
PR - interval -
Measured from the beginning of the P wave to the Beginning of the QRS complex.
Regular with is 0.12-0.20 seconds Should not be longer than one large box
If less than 3 small boxes --> accessory pathways from A to V
If longer = 1st degree AV block Lead II is used to measure it.
QRS complex -
Represents depolarization of the ventricular myocardium
Although termed the "QRS" complex, many complexes do not contain all three waves. These can be
polymorphic or monomorphic.
Downloaded by NELSON KIIRU ()
, lOMoARcPSD|26582732
0.07-0.11 sec in width. QRS widths often vary in different leads
Best leads to look at are usually leads I and V1
QRS should be narrow, the wider the complex the more likley the rythm is ventricular in origen
R prime -
A second R wave in a QRS complex
Best leads to look at a QRS complex -
Lead I, and V1
Low QRS height -
Defined as < 5 mm peak-to-peak in all limb leads or <10 mm in precordial leads
Chronic causes — pulmonary disease, hypothyroidism, obesity, cardiomyopathy
Acute causes — pleural and/or pericardial effusions
Q waves -
Negative deflection preceding the R wave
present only in leads I, AVL, v5, v6 normal Large Q
waves represent myocardial damage
ST segment -
Starts at J point( end of QRS complex) and ends at the beginning of the T wave.
ST segments should be flat in nature
Clinical importance is more based on its level more than length.
ST elevation: is significant for MI ST
depression = MI is eminant slide 40
EKG 1
QT interval -
Measurement of refractory period in which the myocardium would not react to an electrical
impulse. Starting from the beginning of the QRS to the end of the T wave.
Bassets formula -
Qt interval/ rr intervals squared
calculate heart rate
T wave -
Re-polarization of the ventricles
Should have the same polarity as QRS complex
T Waves are very fickle and can be altered by various things
Hyperkalemia can lead to consistently high peaked T waves.
Rand high peaks could be due to ischemic changes
U Wave -
Shallow gentle wave following the T wave
(forget about these for now)
Downloaded by NELSON KIIRU ()
