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POWERPOINT LECTURE ON Electrical Axis of Heart
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ELECTRICAL AXIS OF HEARTELECTRICAL AXIS OF HEART
BYBY
Rear_avisRear_avis
ELECTRICAL AXIS OF HEARTELECTRICAL AXIS OF HEART
Action potential is the movement of ions so it is also called Action potential is the movement of ions so it is also called as electrical current. This current after origin in SA Node as electrical current. This current after origin in SA Node travels in all directions in atria and ventricles.travels in all directions in atria and ventricles.
If we represent movement of current in each direction by If we represent movement of current in each direction by an arrow it will be called as vector. Head of the arrow will an arrow it will be called as vector. Head of the arrow will point towards direction of current and its length will point point towards direction of current and its length will point the magnitude of current.the magnitude of current.
Mean vector of all these vectors is called AXIS of heart.Mean vector of all these vectors is called AXIS of heart.
As left ventricle has largest mass and performs maximum As left ventricle has largest mass and performs maximum function of heart the net current moves in the direction of function of heart the net current moves in the direction of left ventricle i.e downwards and to the left.left ventricle i.e downwards and to the left.
So normal axis of heart is downwards and to the left.So normal axis of heart is downwards and to the left.
CURRENT MOVES IN ALL DIRECTIONS BUT CURRENT MOVES IN ALL DIRECTIONS BUT NET CURRENT MOVES DOWNWARD AND TO NET CURRENT MOVES DOWNWARD AND TO
LEFT TOWARDS APEX OF LEFT VENTRICLE LEFT TOWARDS APEX OF LEFT VENTRICLE
BIPOLAR LIMB LEADS UNIPOLAR LEADSBIPOLAR LIMB LEADS UNIPOLAR LEADS
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NORMAL AXIS AXIS DEVIATIONNORMAL AXIS AXIS DEVIATION
CAUSES OF AXIS DEVIATIONCAUSES OF AXIS DEVIATION
LEFT AXISLEFT AXIS
DEVIATIONDEVIATION
RIGHT AXIS RIGHT AXIS DEVIATIONDEVIATION
EXTREME AXIS OR EXTREME AXIS OR NORTH WEST AXIS NORTH WEST AXIS DEVIATIONDEVIATION
1.HTN1.HTN
2. LVH2. LVH
3. LBBB3. LBBB
4. LAH4. LAH
5. INFERIOR M.I5. INFERIOR M.I
1. RVH1. RVH
2. RBBB2. RBBB
3. LPH3. LPH
4. ANTERIOR M.I4. ANTERIOR M.I
5. PULMONARY5. PULMONARY
EMBOLISMEMBOLISM
6. CHRONIC LUNG6. CHRONIC LUNG
DISEASESDISEASES
7.DEXTROCARDIA7.DEXTROCARDIA
1.VENTRICULAR 1.VENTRICULAR
TACHYCARDIATACHYCARDIA
2. HYPERKALEMIA2. HYPERKALEMIA
3. LEAD3. LEAD
TRANSPOSITIONTRANSPOSITION
4. ARTIFICIAL PACE4. ARTIFICIAL PACE
MAKERMAKER
Determining the AxisDetermining the Axis
Predominantly Positive
Predominantly Negative
Equiphasic
EQUIPHASIC APPROACHEQUIPHASIC APPROACHSTEP 1.STEP 1. Determine which lead among 6 limb leads is equi phasic Determine which lead among 6 limb leads is equi phasic ( equal QRS portion above and below baseline)( equal QRS portion above and below baseline)STEP 2STEP 2 Move to the lead which is perpendicular to this leadMove to the lead which is perpendicular to this lead LEADS I & AVF are perpendicular to each otherLEADS I & AVF are perpendicular to each other LEADS II & AVL are perpendicular to each otherLEADS II & AVL are perpendicular to each other LEADS III & AVR are perpendicular to each otherLEADS III & AVR are perpendicular to each otherSTEP 3.STEP 3. Note the QRS complex is predominantly upwards or Note the QRS complex is predominantly upwards or downwards in this lead downwards in this lead STEP 4STEP 4 If QRS complex is predominantly upward, Axis is on theIf QRS complex is predominantly upward, Axis is on the positive terminal of this lead.positive terminal of this lead. If QRS complex is predominantly downwards Axis is onIf QRS complex is predominantly downwards Axis is on the negative terminal of this lead.the negative terminal of this lead.NOTE:NOTE: If no lead is equi phasic then find the lead with lowestIf no lead is equi phasic then find the lead with lowest voltage of QRS complex and consider it as equiphasicvoltage of QRS complex and consider it as equiphasic
EXAMPLEEXAMPLE
1. LEAD AVF IS EQUI PHASIC1. LEAD AVF IS EQUI PHASIC
2. AVF IS PERPENDICULAR TO LEAD I SO AXIS IS SITUATED ON LEAD I2. AVF IS PERPENDICULAR TO LEAD I SO AXIS IS SITUATED ON LEAD I
3. NOW NOTE THAT LEAD I IS PREDOMONANTLY UPWARDS3. NOW NOTE THAT LEAD I IS PREDOMONANTLY UPWARDS
SO AXIS IS ON POSITIVE TERMINAL OF LEAD ISO AXIS IS ON POSITIVE TERMINAL OF LEAD I
4. POSITIVE TERMINAL OF LEAD I IS AT 0 DEGREE SO AXIS4. POSITIVE TERMINAL OF LEAD I IS AT 0 DEGREE SO AXIS
OF THIS ECG IS ZERO DEGREE WHICH IS NORMALOF THIS ECG IS ZERO DEGREE WHICH IS NORMAL
Q. DETERMINE AXIS BY EQUI PHASIC APPROACHQ. DETERMINE AXIS BY EQUI PHASIC APPROACH
THUMB METHOD TO DETECT ELECTRICAL AXISTHUMB METHOD TO DETECT ELECTRICAL AXIS Place your left thumb over lead I &Right thumb overPlace your left thumb over lead I &Right thumb over lead AVF.lead AVF.
Point the thumb upwards if QRS complex in the respective Point the thumb upwards if QRS complex in the respective lead is predominantly upward and Point the thumb lead is predominantly upward and Point the thumb downwards if QRS complex in the respective lead is downwards if QRS complex in the respective lead is predominantly downwardspredominantly downwards
BOTH THUMBS UPBOTH THUMBS UP = NORMAL AXIS = NORMAL AXIS
LEFT UPLEFT UP RIGHT DOWN RIGHT DOWN = LAD= LAD
LEFT DOWNLEFT DOWN RIGHT UPRIGHT UP = RAD = RAD
BOTH THUMS DOWNBOTH THUMS DOWN = INDETERMINATE AXIS/ = INDETERMINATE AXIS/ NORTH WEST AXIS/ NORTH WEST AXIS/ NO MANS LAND AREANO MANS LAND AREA
NORMAL AXIS NORMAL AXIS (LEAD I & AVF BOTH UPWARDS --- BOTH THUMBS UP)(LEAD I & AVF BOTH UPWARDS --- BOTH THUMBS UP)
LAD LAD (LEAD I UP & AVF DOWN --- LEFT THUMB UP, RIGHT DOWN)(LEAD I UP & AVF DOWN --- LEFT THUMB UP, RIGHT DOWN)
RADRAD ( LEAD I IS DOWN & AVF IS UP– LEFT THUMB UP, RIGHT DOWN ( LEAD I IS DOWN & AVF IS UP– LEFT THUMB UP, RIGHT DOWN
INDETERMINATE AXISINDETERMINATE AXIS ( BOTH LEADS --- DOWN BOTH THUMBS DOWN) ( BOTH LEADS --- DOWN BOTH THUMBS DOWN)
Q. DETERMINE THE AXIS BY THUMB METHODQ. DETERMINE THE AXIS BY THUMB METHOD
THANK YOUTHANK YOU