Axis deviation in ecg

Ventricular tachycardia (VT): types, causes, ECG features and management Thischapter deals with ventricular tachycardia from a clinical perspective, with emphasis on Causes of ventricular tachycardia Patients with ventricular tachycardia almost invariably have significant underlying heart disease. The most common causes are coronary heart disease (acute coronary syndromesor ischemic heart disease), cardiomyopathy (dilated cardiomyopathy, hypertrophic obstructive cardiomyopathy), valvulardisease. Less common causes are arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/ARVD), long QT syndrome, sarcoidosis, Prinzmetal’s angina (coronary vasospasm), electrolyte disorders, congenital heart disease and catecholamine inducedventricular tachycardia. The vast majority of patients with ventricular tachycardia either have coronary arterydisease (ischemic heart disease), heart failure, cardiomyopathy or valvular heartdisease. In these populations one of the strongest predictors ofsudden cardiac deathis left ventricular function. Individuals with reduced left ventricular function (e.g defined as ejection fraction 120 beats per minute). Ventricular tachycardia with rate 100 to 120 beats per minute is referred to as slow ventricular tachycardia.Ventricular tachycardia with rate >250 beats per minute is referred to as ventricular flutter. • Wide QRS complexes (QRS duration≥0,12 s). Types of ventricular tachycardia The ECG allows for subclassification of ventricular tachycard...

Cardiac axis represents the sum of depolarisation vectors generated by individual cardiac myocytes. Clinically is is reflected by the ventricular axis, and interpretation relies on determining the relationship between the QRS axis and limb leads of the ECG (below diagram) Since the left ventricle makes up most of the heart muscle under normal circumstances, normal cardiac axis is directed downward and slightly to the left: • Normal Axis= QRS axis between -30° and +90°. Abnormal axis deviation, indicating underlying pathology, is demonstrated by: • 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”). • A positive QRSin Lead Iputs the axis in roughly the same direction as lead I. • A positive QRSin Lead aVFsimilarly 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). 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 QRSin Lead Iputs the axis in roughly the same direction as lead I. • A positive QRSin Lead IIsimilarly 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). Key ...

Figure 38. The electrical axis of the heart (heart axis). As evident from the figure, the normal heart axis is between –30° and 90°. If the axis is more positive than 90° it is referred to as right axis deviation. If the axis is more negative than –30° it is referred to as left axis deviation. The axis is calculated (to the nearest degree) by the • Normal axis: Net positive QRS complex in leads I and II. • Right axis deviation: Net negative QRS complex in lead I but positive in lead II. • Left axis deviation: Net positive QRS complex in lead I but negative in lead II. • Extreme axis deviation (–90°to 180°): Net negative QRS complex in leads I and II. Heart axis deviation: right axis deviation (RAD) and left axis deviation (LAD) Causes of right axis deviation Normal in newborns. Right ventricular hypertrophy. Acute cor pulmonale (pulmonary embolism). Chronic cor pulmonale (COPD, pulmonary hypertension, pulmonary valve stenosis). Lateral ventricular infarction. Causes of left axis deviation Causes of extreme axis deviation Rare. Most likely due to misplaced limb electrodes. If the rhythm is tachycardia with wide QRS complexes, then This article is part of the comprehensive chapter:

Evaluation of ECG Findings Electrocardiograms (ECGs) are used in clinics and hospitals to diagnose cardiovascular disease in both adults and children. From preventive screening based on risk factors to acute diagnosis associated with specific symptoms, ECGs can help identify or rule out cardiac problems in patients. When reviewing the results of an ECG, it is important that they are interpreted by a Normal or Normal Variant ECG Readings Normal ECGs do not require further workup unless clinical symptoms, examination or history suggest cardiac involvement. Commonly seen normal or normal variant ECG readings included in the report include the following: • Sinus bradycardia • Sinus arrhythmia • Appropriate sinus tachycardia • Right ventricular conduction delay or incomplete right bundle-branch block without right ventricular hypertrophy or right-axis deviation • Isolated intraventricular conduction delay • Rightward QRS axis less than or equal to 8 years of age • Early repolarization • Nonspecific ST-T wave changes • Juvenile T-wave pattern • QTc greater to or equal than 0.45 s by computer but ECG interpretation states normal Abnormal ECG Readings With Low Likelihood of Correlation to Cardiac Disease Patients with these readings may need to be seen by a cardiologist. Correlate the ECG reading with the history, examination and any symptoms the patient might have and discuss the reading with a cardiologist to assess the need for an office visit. Our cardiologists are available f...

In atrial fibrillation, the atria no longer conduct electricity from the sinoatrial node in an orderly fashion. As a result, P-waves are lost. As a result of disordered atrial activity, only occasional waves of depolarisation pass through to the atrioventricular node and cause ventricular activation. This causes the typical irregular rhythm. A short PR-interval indicates abnormally short conduction time between the atria and ventricles. This is typically caused by the presence of an accessory pathway between the atria and ventricles. WPW syndrome is an example of this kind of disorder. In WPW syndrome, an accessory pathway known as the bundle of Kent is present. Most individuals are asymptomatic, however, there is a risk of sudden death without treatment.

• Sinus tachycardia–the most common abnormality (seen in 44% of patients with PE) • Complete or incomplete RBBB (18%) • Right ventricular strain pattern –T wave inversions in the right precordial leads (V1-4) ± the inferior leads (II, III, aVF). This pattern is associated with high pulmonary artery pressures (34%) • Right axis deviation(16%). Extreme right axis deviation may occur, with axis between zero and -90 degrees, giving the appearance of left axis deviation (“pseudo left axis”) • Dominant R wave in V1– a manifestation of acute right ventricular dilatation • Right atrial enlargement (P pulmonale) –peaked P wave in lead II > 2.5 mm in height (9%) • S IQ IIIT III pattern– deep S wave in lead I, Q wave in III, inverted T wave in III (20%). This “classic” finding is neither sensitive nor specific for PE • Clockwise rotation –shift of the R/S transition point towards V6 with a persistent S wave in V6 (“pulmonary disease pattern”), implying rotation of the heart due to right ventricular dilatation • Atrial tachyarrhythmias – • Non-specific ST segment and T wave changes, including ST elevation and depression (50%) Simultaneous T wave inversions in the inferior (II, III, aVF) and right precordial leads (V1-4) is the most specific finding in favour of PE, with reported specificities of up to 99% in one study. ECG findings compared to Acute Coronary Syndrome T-wave inversion is commonly associated with acute coronary syndrome (ACS). Both ACS and PE can present with elevated t...

Learning Objectives Upon completion of the accompanying narrative and practice the student will be able to: • Recall which major coronary artery supports each region of the heart • Associate the views of a 12-Lead ECG with specific surfaces of the heart • Determine the presence of cardiac axis deviation • Understand Einthoven's Triangle 12-Lead ECG • People may choose to analyze ECG’s in a number of different ways. The sequence doesn’t necessarily matter as long as you gather and report the proper information each time. I read from left to right as much as possible (in anatomic groupings). • If your protocols are different, always follow them. • The following slides will review the leads, surfaces, and associated coronary arteries which commonly supply that portion of the heart. Description • Axis is the general flow of electricity as it passes through the heart from the SA node all the way to the Purkinje fibers. • It is typically obtained from the limb or frontal plane leads. • The axis of the heart can change for a number of different reasons from birth defects which affect the physical location of the heart i.e. Dextrocardia, to obesity to pregnancy among others. • If you can envision a circle with a centered vertical and horizontal line superimposed over the chest, you would note that the normal heart is located in the lower left quadrant of this circle. • You will be provided an example of this image in a few slides.

• Sinus tachycardia–the most common abnormality (seen in 44% of patients with PE) • Complete or incomplete RBBB (18%) • Right ventricular strain pattern –T wave inversions in the right precordial leads (V1-4) ± the inferior leads (II, III, aVF). This pattern is associated with high pulmonary artery pressures (34%) • Right axis deviation(16%). Extreme right axis deviation may occur, with axis between zero and -90 degrees, giving the appearance of left axis deviation (“pseudo left axis”) • Dominant R wave in V1– a manifestation of acute right ventricular dilatation • Right atrial enlargement (P pulmonale) –peaked P wave in lead II > 2.5 mm in height (9%) • S IQ IIIT III pattern– deep S wave in lead I, Q wave in III, inverted T wave in III (20%). This “classic” finding is neither sensitive nor specific for PE • Clockwise rotation –shift of the R/S transition point towards V6 with a persistent S wave in V6 (“pulmonary disease pattern”), implying rotation of the heart due to right ventricular dilatation • Atrial tachyarrhythmias – • Non-specific ST segment and T wave changes, including ST elevation and depression (50%) Simultaneous T wave inversions in the inferior (II, III, aVF) and right precordial leads (V1-4) is the most specific finding in favour of PE, with reported specificities of up to 99% in one study. ECG findings compared to Acute Coronary Syndrome T-wave inversion is commonly associated with acute coronary syndrome (ACS). Both ACS and PE can present with elevated t...

Figure 38. The electrical axis of the heart (heart axis). As evident from the figure, the normal heart axis is between –30° and 90°. If the axis is more positive than 90° it is referred to as right axis deviation. If the axis is more negative than –30° it is referred to as left axis deviation. The axis is calculated (to the nearest degree) by the • Normal axis: Net positive QRS complex in leads I and II. • Right axis deviation: Net negative QRS complex in lead I but positive in lead II. • Left axis deviation: Net positive QRS complex in lead I but negative in lead II. • Extreme axis deviation (–90°to 180°): Net negative QRS complex in leads I and II. Heart axis deviation: right axis deviation (RAD) and left axis deviation (LAD) Causes of right axis deviation Normal in newborns. Right ventricular hypertrophy. Acute cor pulmonale (pulmonary embolism). Chronic cor pulmonale (COPD, pulmonary hypertension, pulmonary valve stenosis). Lateral ventricular infarction. Causes of left axis deviation Causes of extreme axis deviation Rare. Most likely due to misplaced limb electrodes. If the rhythm is tachycardia with wide QRS complexes, then This article is part of the comprehensive chapter:

Learning Objectives Upon completion of the accompanying narrative and practice the student will be able to: • Recall which major coronary artery supports each region of the heart • Associate the views of a 12-Lead ECG with specific surfaces of the heart • Determine the presence of cardiac axis deviation • Understand Einthoven's Triangle 12-Lead ECG • People may choose to analyze ECG’s in a number of different ways. The sequence doesn’t necessarily matter as long as you gather and report the proper information each time. I read from left to right as much as possible (in anatomic groupings). • If your protocols are different, always follow them. • The following slides will review the leads, surfaces, and associated coronary arteries which commonly supply that portion of the heart. Description • Axis is the general flow of electricity as it passes through the heart from the SA node all the way to the Purkinje fibers. • It is typically obtained from the limb or frontal plane leads. • The axis of the heart can change for a number of different reasons from birth defects which affect the physical location of the heart i.e. Dextrocardia, to obesity to pregnancy among others. • If you can envision a circle with a centered vertical and horizontal line superimposed over the chest, you would note that the normal heart is located in the lower left quadrant of this circle. • You will be provided an example of this image in a few slides.