Cardiac axis abnormalities in ECG

Case-1: ECG with Normal axis ; Case-2: ECG with left axis deviation
Case-3: ECG with extreme right axis deviation
Case-4: ECG with right axis deviation
Clinical significance of cardiac axis
What is Electrical Axis? Types of electrical axis
What are the Methods of ECG Axis Interpretation? How ECG axis can be determined?
How Ventricular (QRS) Axis is determined in Bundle Branch Blocks ?
What is Undetermined axis/ Indeterminate axis?
What are the causes of abnormal heart axis?
What are the causes of Right Axis Deviation(RAD)?
What are the causes of Left Axis Deviation?
What are the causes of Extreme Axis Deviation (indeterminate axis/ northwest axis)?

1. Fundamentals of ECG Cardiac axis abnormalities in ECG Dr. Md.Toufiqur Rahman MBBS, FCPS, MD, FACC, FESC, FRCP, FSCAI, FCCP,FAPSC, FAPSIC, FAHA,FACP Professor & head of Cardiology CMMC, Manikganj Ex professor of cardiology, NICVD, Dhaka [email protected]

2. Fundamentals of ECG C ardiac axis abnormalities in ECG Case-1: ECG with Normal axis ; Case-2 : ECG with left axis deviation Case-3: ECG with extreme right axis deviation Case-4 : ECG with right axis deviation Clinical significance of cardiac axis What is Electrical Axis? Types of electrical axis What are the Methods of ECG Axis Interpretation? How ECG axis can be determined? How Ventricular (QRS) Axis is determined in Bundle Branch Blocks ? What is Undetermined axis/ Indeterminate axis? What are the causes of abnormal heart axis? What are the causes of Right Axis Deviation(RAD)? What are the causes of Left Axis Deviation? What are the causes of Extreme Axis Deviation (indeterminate axis/ northwest axis)?

3. Fundamentals of ECG C ardiac axis abnormalities in ECG   Case1: A 54 years old gentleman presented with palpitations for last 3 months. His pulse 76 beats/min, B.P. 140/90 mm Hg. He had the following ECG. Comment about QRS complex axis.

4. Fundamentals of ECG C ardiac axis abnormalities in ECG   Case2: A 48 years old gentleman presented with vertigo and dizziness for last 2 months. His pulse beats/min, B.P. 140/90 mm Hg. He had the following ECG. Comment about QRS complex axis .

5. Fundamentals of ECG C ardiac axis abnormalities in ECG   Case3: A 32 years old lady presented with Shortness of Breath(SOB) for last 6 months . She is a diagnosed case of ASD( secundum ) with Pulmonary hypertension(PASP-102 mmHg) with clubbing . She had the following ECG. Comment about QRS complex axis.

6. Fundamentals of ECG Clinical significance of cardiac axis The axis of the ECG is the major direction of the overall electrical activity of the heart. It can be normal, leftward (left axis deviation, or LAD), rightward (right axis deviation, or RAD) or indeterminate (northwest axis). The QRS axis is the most important to determine. However, the P wave or T wave axis can also be measured. To determine the QRS axis, the limb leads (not the precordial leads) need to be examined. Being able to interpret the electrical axis may offer insight into the cardiac pathology and help avoid unnecessary imaging tests .

7. Fundamentals of ECG Types of Electrical axis There are five main electrical axis:  normal axis left axis deviation (LAD) right axis deviation (RAD) extreme axis deviation, and  indeterminate axis 

8. Fundamentals of ECG Types of Electrical axis Normal Axis  = QRS axis between -30° and +90°. Left Axis Deviation  = QRS axis less than -30°. Right Axis Deviation  = QRS axis greater than +90°. Extreme Axis Deviation  = QRS axis between -90° and 180° (AKA “Northwest Axis”).

9. Fundamentals of ECG What are the Methods of ECG Axis Interpretation? How ECG axis can be determined? There are several complementary approaches to estimating QRS axis, which are summarized below: The Quadrant Method  – (Lead I and aVF ) Three Lead analysis  – (Lead I, Lead II and aVF ) Isoelectric Lead analysis Super SAM the Axis Man  

10. Fundamentals of ECG Method 1 – The Quadrant Method The most efficient way to estimate axis is to look at LEAD I and LEAD aVF . Examine the QRS complex in each lead and determine if it is Positive, Isoelectric ( Equiphasic ) or Negative: A positive QRS in Lead I puts the axis in roughly the same direction as lead I. A positive QRS in Lead aVF  similarly aligns the axis with lead aVF . Combining both coloured areas – the quadrant of overlap determines the axis. So If Lead I and aVF are  both  positive, the axis is between 0° and +90° (i.e. normal axis).

11. Fundamentals of ECG Method 1 – The Quadrant Method

12. Fundamentals of ECG Method 1 – The Quadrant Method

13. Fundamentals of ECG C ardiac axis abnormalities in ECG   Case1: A 54 years old gentleman presented with palpitations for last 3 months. His pulse 76 beats/min, B.P. 140/90 mm Hg. He had the following ECG. Comment about QRS complex axis.

14. Fundamentals of ECG C ardiac axis abnormalities in ECG   Case2: A 48 years old gentleman presented with vertigo and dizziness for last 2 months. His pulse beats/min, B.P. 140/90 mm Hg. He had the following ECG. Comment about QRS complex axis .

15. Fundamentals of ECG C ardiac axis abnormalities in ECG   Case3: A 32 years old lady presented with Shortness of Breath(SOB) for last 6 months . She is a diagnosed case of ASD( secundum ) with Pulmonary hypertension(PASP-102 mmHg) with clubbing . She had the following ECG. Comment about QRS complex axis.

16. Fundamentals of ECG Method 2: Three Lead analysis – (Lead I, Lead II and aVF ) Next we add in Lead II to the analysis of Lead I and aVF A positive QRS in Lead I puts the axis in roughly the same direction as lead I. A positive QRS in Lead II similarly aligns the axis with lead II. We can then combine both coloured areas and the area of overlap determines the axis. So If Lead I and II are  both  positive, the axis is between -30° and +90° (i.e. normal axis).

17. Fundamentals of ECG Method 2: Three Lead analysis – (Lead I, Lead II and aVF ) The combined evaluation of Lead I, Lead II and  aVF  – allows rapid and accurate QRS assessment. The addition of Lead II can help determine pathological LAD from normal axis/physiological LAD Lead III  or   aVF  can  both  be used in three lead analysis

18. Fundamentals of ECG Method 2: Three Lead analysis – (Lead I, Lead II and aVF )

19. Fundamentals of ECG Method 3 – The Isoelectric Lead This method allows a more precise estimation of QRS axis, using the axis diagram below .   Step 1: Find the isoelectric lead. The isoelectric ( equiphasic ) lead is the frontal lead with zero net amplitude. This can be either: A biphasic QRS where R wave height = Q or S wave depth. A flat-line QRS with no discernible features. Step 2: Find the positive leads. Look for the leads with the tallest R waves (or largest R/S ratios) Step 3: Calculate the QRS axis. The QRS axis is at 90° to the isoelectric lead, pointing in the direction of the positive leads. Key Principles If the QRS is POSITIVE in any given lead, the axis points in  roughly  the same direction as this lead. If the QRS is NEGATIVE in any given lead, the axis points in  roughly  the opposite direction to this lead. If the QRS is ISOELECTRIC ( equiphasic ) in any given lead ( positive deflection = negative deflection ), the axis is at 90° to this lead.

20. Fundamentals of ECG What is Undetermined axis/ Indeterminate axis? When all extremity leads are biphasic, the axis is directed to the front or back, in a transverse plane. The axis is then  undetermined.

21. Fundamentals of ECG What are the causes of abnormal heart axis? The direction of the vector can changes under different circumstances: When the heart itself is rotated (right ventricular overload), obviously the axis turns with it. In case of ventricular hypertrophy, the axis will deviate toward the greater electrical activity and the vector will turn toward the hypertrophied tissue. Infarcted tissue is electrically dead. No electrical activity is registered and the QRS vector turns away from the infarcted tissue In conduction problems, the axis deviates too. When the right ventricle depolarizes later than the left ventricle, the axis will turn to the right (RBBB). This is because the right ventricle will begin the contraction later and therefore will also finish later. In a normal situation the vector is influenced by the left ventricle, but in RBBB only the right ventricle determines it.

22. Fundamentals of ECG What are the causes of Right Axis Deviation(RAD)? Normal variation (e.g., children, young adults) Limb-lead reversal (left- and right-arm electrodes) Right ventricular overload syndromes (acute or chronic) Right ventricular hypertrophy Conduction defects: left posterior fascicular block, right bundle branch block Lateral wall myocardial infarction Preexcitation syndromes (e.g., Wolff-Parkinson-White syndrome) Ventricular ectopic rhythms (e.g., ventricular tachycardia) Congenital heart disease (e.g., secundum atrial septal defect) Dextrocardia Left pneumothorax Mechanical shift, such as with inspiration or emphysema Conditions that cause right-ventricular strain (e.g., pulmonary embolism, pulmonary stenosis, pulmonary hypertension, chronic lung disease, and resultant cor pulmonale

23. Fundamentals of ECG What are the causes of Left Axis Deviation(LAD )? Normal variation (physiologic, often age-related change) Left ventricular hypertrophy Conduction defects: left bundle branch block, left anterior fascicular block Inferior wall myocardial infarction Preexcitation syndromes (e.g., Wolff-Parkinson-White syndrome) Ventricular ectopic rhythms (e.g., ventricular tachycardia) Congenital heart disease (e.g., primum atrial septal defect, endocardial cushion defect) Hyperkalemia Emphysema Mechanical shift, such as with expiration or raised diaphragm (e.g., pregnancy, ascites, abdominal tumor, organomegaly ) Pacemaker-generated rhythm or paced rhythm

24. Fundamentals of ECG What are the causes of Extreme Axis Deviation (indeterminate axis/ northwest axis)? Ventricular rhythms – e.g.VT , AIVR, ventricular ectopy Hyperkalaemia Severe right ventricular hypertrophy