![]() Left atrial hypertrophy or prolonged atrial depolarisation and left axis deviation are often present and poor R wave progression is commonly seen. Other non-voltage criteria are common in left ventricular hypertrophy. It is an advantage to have old electrocadiograms for comparison. The presence of these ST segment changes can cause diagnostic difficulty in patients complaining of ischaemic-type chest pain failure to recognise the features of left ventricular hypertrophy can lead to the inappropriate administration of thrombolytic therapy.įurthermore, in patients known to have left ventricular hypertrophy it can be difficult to diagnose confidently acute ischaemia on the basis of ST segment changes in the left precordial leads. This “strain” pattern is seen in the left precordial leads and is associated with reciprocal ST segment elevation in the right precordial leads. Typical repolarisation changes seen in left ventricular hypertrophy are ST segment depression and T wave inversion. Even when high amplitude QRS complexes are seen in association with non-voltage criteria-such as ST segment and T wave changes-a diagnosis cannot be made with confidence. Voltage criteria lack specificity in this group because young people often have high amplitude QRS complexes in the absence of left ventricular disease. The electrocardiographic diagnosis of left ventricular hypertrophy is difficult in individuals aged under 40. The electrocardiographic features of left ventricular hypertrophy are classified as either voltage criteria or non-voltage criteria. Left atrial enlargement can occur in association with systemic hypertension, aortic stenosis, mitral incompetence, and hypertrophic cardiomyopathy. However, a pronounced notch with a peak-to-peak interval of >0.04 s suggests left atrial enlargement.Īny condition causing left ventricular hypertrophy may produce left atrial enlargement as a secondary phenomenon. Normal P waves may be bifid, the minor notch probably resulting from slight asynchrony between right and left atrial depolarisation. Prolongation of P wave duration to greater than 0.12 s is often found in association with a left atrial abnormality. A large negative deflection (>1 small square in area) suggests a left atrial abnormality. Early right atrial forces are directed anteriorly giving rise to an initial positive deflection these are followed by left atrial forces travelling posteriorly, producing a later negative deflection. In addition, left atrial depolarisation may be delayed, which may prolong the duration of the P wave. The changes of left atrial hypertrophy are therefore seen in the late portion of the P wave. Left atrial depolarisation contributes to the middle and terminal portions of the P wave. The term left atrial abnormality is used to imply the presence of atrial hypertrophy or dilatation, or both. ![]()
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