If the electrical axis is between -30° to -90° this is considered left axis deviation. If the electrical axis is between +90° to +180° this is considered right axis deviation (RAD
Radian
The radian is the standard unit of angular measure, used in many areas of mathematics. An angle's measurement in radians is numerically equal to the length of a corresponding arc of a unit circle; one radian is just under 57.3 degrees (when the arc length is equal to the radius).
Electrocardiography
Electrocardiography is the process of producing an electrocardiogram, a recording – a graph of voltage versus time – of the electrical activity of the heart using electrodes placed on the skin. These electrodes detect the small electrical changes that are a consequence of cardiac muscle depolarization followed by repolarization during each cardiac cycle. Changes in the normal EC…
Full Answer
What are the symptoms of left axis deviation?
Other conditions that can cause an LBBB include:
- coronary artery disease
- heart failure
- high blood pressure
- problems with the aortic valve
What does left axis deviation mean?
Left axis deviation. In electrocardiography, left axis deviation is a condition where the mean electrical axis of ventricular contraction of the heart lies in a frontal plane direction between −30° and −90°. This is reflected by a QRS complex positive in lead I and negative in leads aVF and II.
What does an abnormal left axis deviation mean?
Left axis deviation, sometimes known in medicine simply as “LAD,” is an abnormal reading on the left axis of an electrocardiogram (EKG) graph. Healthcare professionals use EKGs to map and graph cardiac activity for a wide variety of patients, some with heart diseases and conditions and others who are otherwise healthy.
What is the meaning of left axis deviation in an ECG?
A: Left axis deviation is usually a normal variation in the ECG in which the currents arising from the heart picked up by ECG have a leftward deviation. It is not an abnormal finding and requires...
What does left axis deviation indicate?
In electrocardiography, left axis deviation (LAD) is a condition wherein the mean electrical axis of ventricular contraction of the heart lies in a frontal plane direction between −30° and −90°. This is reflected by a QRS complex positive in lead I and negative in leads aVF and II.
What does right axis deviation indicate?
When right axis deviation is a new finding, it can be due to an exacerbation of lung disease, a pulmonary embolus, or simply a tachycardia. If right axis deviation is a change from previous ECGs, question the patient for symptoms consistent with an exacerbation of lung disease or a pulmonary embolus.
What is right and left axis deviation?
The normal QRS axis should be between -30 and +90 degrees. Left axis deviation is defined as the major QRS vector, falling between -30 and -90 degrees. Right axis deviation occurs with the QRS axis and is between +90 and +180 degrees.
What causes left axis deviation of the heart?
Left anterior fascicular block (LAFB): LAFB probably is the most common cause of left axis deviation and is common in persons without overt cardiac disease.
Does left axis deviation mean heart disease?
The results were that the development of left axis deviation in men 40 to 59 yr of age, independent of blood pressure is a significant predictor of ischemic heart disease events that are usually manifest 5 to 10 yr after the onset of this electrocardiographic abnormality.
Should I be worried about right axis deviation?
Although not a dangerous finding in and of itself, axis deviation may be an indication of a serious underlying condition. A careful history to elicit acute cardiac injury is therefore of utmost importance.
What does right axis deviation look like on ECG?
5:0710:59Understanding ECG Axis and Axis Deviation - YouTubeYouTubeStart of suggested clipEnd of suggested clipPositive or negative now if the electrical activity is traveling in that direction. Remember this isMorePositive or negative now if the electrical activity is traveling in that direction. Remember this is a right axis deviation then in fact generally there is a negative flow of electricity across lead 1
What is pulmonary disease pattern on ECG?
ECG demonstrates many of the features of chronic pulmonary disease: Rightward QRS axis (+90 degrees) Peaked P waves in the inferior leads > 2.5 mm (P pulmonale) with a rightward P-wave axis (inverted in aVL) Clockwise rotation of the heart with a delayed R/S transition point (transitional lead = V5)
What is abnormal ECG?
Abnormal results can signify several issues. These include: Defects or abnormalities in the heart's shape and size: An abnormal ECG can signal that one or more aspects of the heart's walls are larger than another meaning that the heart is working harder than normal to pump blood.
Which of the following would be most likely to cause left axis deviation?
Left anterior fascicular block is the most common cause of left axis deviation [2].
When does left axis deviation occur?
Left axis deviation occurs when the QRS axis falls between -30 and -90. There are a variety of causes, including left anterior fascicular block and left ventricular hypertrophy.
What are the symptoms of left axis deviation?
For example, if left ventricular hypertrophy (LVH) is the cause of LAD, symptoms can include shortness of breath, fatigue, chest pain (especially with exercise), heart palpitations, dizziness, or fainting. If a conduction defect such as left bundle branch block is ...
What is the axis of the left ventricle?
In a normal axis, QRS is between -30° and +90°. In contrast to that, left axis deviation (LAD) is defined as QRS axis between −30° and −90°, and right axis deviation is defined as QRS axis greater than +90°, ...
What is the cardiac axis?
Cardiac axis in electrocardiography represents the sum of depolarization vectors generated by individual cardiac myocytes. To interpret the cardiac axis, one has to determine the relationship between the QRS axis and limb leads of the ECG. Usually, left ventricles makes up most of the heart muscles, so a normal cardiac axis is directed downward ...
What causes a left anterior fascicular block?
Common causes of LAD include left anterior fascicular block (or hemiblock) and inferior myocardial infarction. Less commonly LAD may be a normal variant, particularly in obese or stocky individuals, or it may be associated with Wolff–Parkinson–White syndrome or an ostium primum atrial septal defect.
What is considered left axis deviation?
If the electrical axis is between -30° to -90° this is considered left axis deviation.
What causes right axis deviation?
These include right ventricular hypertrophy, reduced muscle mass of left ventricle, altered conduction pathways and change in the position of the heart in the chest.
What would happen if the left posterior fascicle was blocked?
Blockage of the left posterior fascicle would lead to activation of the anterior portion of the left ventricle followed by activation of the rest of the ventricle in a superior to inferior direction and directed towards the right. This would lead to right axis deviation findings on an ECG.
How to determine the heart axis of a lead?
After locating the axis of the lead on the hexaxial reference system, identify the lead which is perpendicular to it (lead b). If lead b is positive, the electrical heart axis can be estimated to lie within the quadrant between axis of lead a and lead b.
What causes depolarization of the left ventricle?
For example, scarring and atrophy caused by ischaemia of the left ventricle will cause depolarisation of the left side of the heart to be less forceful. Hence, depolarisation of the right ventricle will be greater in amplitude than left, shifting the axis to the right.
What causes the left side of the heart to be less forceful?
For example, scarring and atrophy caused by ischaemia of the left ventricle will cause depolarisation of the left side of the heart to be less forceful.
What does a positive ECG trace mean?
In general, a positive (upwards) deflection of an ECG trace demonstrates an electrical activity that moves towards the measuring electrode , whereas a negative (downwards) deflection of an ECG trace demonstrates an electrical activity that moves away from the measuring electrode. The electrical heart axis can be estimated from the ECG by using the quadrant method or degree method.
What causes right axis deviation 6?
Abnormalities of axis are rarely specific in the diagnosis of congenital heart diseases. Tetralogy of Fallot, transposition of the great arteries, total anomalous pulmonary venous return, ventricular and atrial septal defect may causes cause right-axis deviation 6.
What happens when you lose leftward forces?
In patients with lateral myocardial infarction, the loss of leftward forces may result in a rightward shift of the QRS vector.
What is the most common lead placement error?
Reversal of the arm leads is the most common lead placement error. It is the easiest to recognize because of a negative P wave in lead I in patients with sinus rhythm, which is unusual even in the presence of heart disease 3. Left and right arm leads reversal: Negative P wave in lead I. Lead I is upside down.
Which leads have inverted T waves?
Inverted T waves in leads I, aVL, V5, and V6 may also be present in patients with lateral myocardial infarction.
Is lead II aVL or aVL?
Lead II is actually lead III and vice versa. Lead aVR is actually lead aVL and vice versa. In patients with atrial fibrillation or unidentifiable P waves, the morphology of the ventricular complexes in leads I, V5, and V6 should be similar. If the polarity of the QRS complex in lead I is opposite that in the left precordial leads, ...
Is lead AVR upside down?
Lead aVR is actually lead aVL and vice versa. When the left and right arm leads are reversed, the EKG reveals the following changes: Lead I is upside down because the polarity of the lead is reversed. Lead II is actually lead III and vice versa. Lead aVR is actually lead aVL and vice versa.
Why does hyperkalemia cause left axis deviation?
Left-axis deviation that occur in hyperkalemia are due to a intra-venticular conduction delay, which causes a progressive widening of the QRS complex.
Which direction does the QRS axis shift with age?
Normal variation. The mean QRS axis tends to shift leftward with increasing age. The leftward shift of the QRS axis with aging is particularly prevalent in overweight subjects and is more pronounced in older obese men than in older obese women 3.
Which axis does the QRS vector shift to?
Most obese patients without clinical heart disease have normal EKGs, with the mean QRS vector shifting to the left with increasing obesity 3.
What is the P axis of emphysema 4?
Low voltage in limb leads, right QRS axis deviation (>90°) or left QRS axis deviation (beyond -30°), combined with a P-axis >60° , are reported to be pathognomonic for emphysema 4.
What does a shift to the right of 30° from the patient's former electrical axis mean?
that a shift to the right of 30° from the patient's former electrical axis, regardless of where that axis might be, signalled right ventricular complications and early cor pulmonale when coupled to a fall in arterial blood 02 saturation below 85 percent.
What is the orientation of the QRS axis?
It is customary to refer to the orientation of the QRS axis as no axis deviation (NAD) from normal, left axis deviation (LAD) and right axis deviation (RAD). By definition
What is the QRS axis of a fascicular block?
Often the tracings of patients with fascicular block may change because the block is intermittent. Hence the QRS axis may vary between an area around −10° or −15° and the more definitive areas of marked left axis deviation (-30° to −60°). Precise determinations of angle alpha thus become critical. If the angle lies between −30° and −45° it is useful to produce shifts of the diaphragm (deep breathing, change in bodily posture) to test the stability of the axis. If it varies, the serious pathologic nature of the axis deviation is less likely. The numeral values for such variation, however, need documentation.
What is the electrical axis of the QRS?
the term electrical axis of the QRS refers to the mean manifest electrical potential in space responsible for this electrocardiographic complex. This potential has both size and direction and it may be treated as a vectorial quantity. Because it occurs in space (the space being the thorax, or, more widely, the human torso) it has frontal, ...
Is the frontal plane axis needed for electrocardiogram?
It is thus becoming evident that in clinic al interpretation of the electrocardiogram, detailed and specific measurements of the frontal plane QRS axis and its variations are now needed. Numerical values of angle alpha, previously considered unnecessary, are becoming important. Furthermore, actuarial studies done in a specific manner addressed to smaller segments of the frontal plane axis, especially segments of left axis, will be necessary in considering the problems of fascicular blocks and their ultimate prognoses. Such investigations have recently been initiated.
Can LPFB shift rightward?
has indicated a shift rightward of 50° (a change from an axis of +10° to +60°) without actually entering the sector of right axis deviation (ie beyond + 90°), can occur with intermittent LPFB. Similarly, in chronic obstructive lung disease it has been recently emphasized
Is axis deviation a safe rule?
Axis deviations of small or moderate degree have, in general, been given little weight if no clinical situation emphasized their value, and this remains a safe rule. However, under certain specific circumstances, this philosophy has changed. In particular there is recent emphasis upon axis deviation as primary information in the diagnosis of those intraventricular conduction defects now called the fascicular blocks,
Overview
Defining left axis deviation
Cardiac axis in electrocardiography represents the sum of depolarization vectors generated by individual cardiac myocytes. To interpret the cardiac axis, one has to determine the relationship between the QRS axis and limb leads of the ECG. Usually, left ventricles makes up most of the heart muscles, so a normal cardiac axis is directed downward and slightly to the left. In a normal axis, QRS is between -30° and +90°. In contrast to that, left axis deviation (LAD) is defined as QR…
Determining left axis deviation
Determining the electrical axis can provide insight into underlying disease states and help steer the differential diagnosis. There are several methods to determining the ECG axis. The easiest method is the quadrant method, where one looks at lead I and lead aVF. First, examine the QRS complex in both leads I and avF and determine if the QRS complex is positive (height of R wave > S wave), equiphasic (R wave = S wave), or negative (R wave < S wave). If lead I is positive and le…
Causes
There are several potential causes of LAD. These include normal variation, left ventricular hypertrophy, conduction defects, inferior wall myocardial infarction, preexcitation syndrome, ventricular ectopic rhythms, congenital heart disease, hyperkalemia, emphysema, mechanical shift and pacemaker-generated paced rhythm. Normal variation causing LAD is an age-related physiologic change. Conduction defects such as left bundle branch block or left anterior fascicula…
Signs and symptoms
Left axis deviation symptoms depend on the underlying cause. For example, if left ventricular hypertrophy is the cause of LAD, symptoms can include shortness of breath, fatigue, chest pain (especially with exercise), palpitations, dizziness, or fainting. If a conduction defect such as left bundle branch block is the cause of LAD, there may not be any symptoms unless the conduction defect is caused by heart failure, in which case there can be symptoms of heart failure such as sh…
Treatment
Left axis deviation per se does not require treatment, however the underlying cause can be treated. If left ventricular hypertrophy is the cause of LAD, treatment depends on the underlying cause of the hypertrophy. If high blood pressure is the cause of LVH, then treatment is targeted at lowering blood pressure and preventing further enlargement of the left ventricle by using medications such as angiotensin-converting enzyme inhibitors (ACE inhibitors), angiotensin recep…
See also
• Right axis deviation