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5.3 Left atrial hypertrophy
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5.3 Left atrial hypertrophy

All conditions causing left ventricular hypertrophy may produce left atrial enlargement as a secondary event. Left atrial enlargement can occur in association with systemic arterial hypertension, mitral stenosis, other damages of valves, and hypertrophic cardiomyopathy.

The term left atrial enlargement is used to mean the presence of atrial hypertrophy or dilatation. Left atrial depolarization contributes to the middle and terminal portions of the P wave. The changes of left atrial hypertrophy are therefore seen more in the late portion of the P wave. Left atrial depolarization may be delayed, and may prolong the duration of the P wave.

Early right atrial forces are directed anteriorly giving rise to an initial positive deflection. These are followed by left atrial forces spreading posteriorly, producing a later negative deflection. A large negative deflection suggests a left atrial abnormality. Prolongation of P wave duration to greater than 0.12 s. is often found in association with a left atrial abnormality (so-called interatrial blockage). Normal P waves may be bifid, the minor notch perhaps resulting from slight asynchrony between right and left atrial depolarization. However, a pronounced notch with a peak-to-peak interval of >0.04 s. suggests left atrial enlargement.

 

Figure 48 — Left atrium hypertrophy

Signs of right atrial hypertrophy:

P wave is longer than 0.12 s., in left standard leads and V1 P wave is biphasic.

Often occurred left deviation of atria axis.

QRS complex and T wave in simply left atrium enlargement is not changed.



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