Findings<br />Rate: 84/min<br />Atrial rhythm<br />P wave axis - 90<br />P ‘ – L II , L III,<br />aVF ,V2 to V6 <br />P --L I, aVR , a VL, V1<br />QRS axis normal<br />T inversion L II , L III, aVF<br /> ST depression L III, aVF<br />Findings of ectopic atrial rhythm<br />
Repeat ECG taken for the patient reverted back to sinus rhythm and was similar to ECG 1 <br />
<ul><li>To differentiate rightatrial from left atrial rhythm
P wave morphology is useful in differentiating left from right atrial foci.
This is a function of the anatomical relationship of the atria, with the left atrium being a more posterior and leftward structure than the right atrium.
As such, leads V1 and aVL are useful discriminators. </li></li></ul><li>Left atrial<br />Right atrial<br /><ul><li>A positive or biphasic P wave in aVL has a positive predictive accuracy of 83% and negative predictive value of 85% for a right atrial focus.
In contrast, a positive P wave in V1 is a feature of left atrial foci. It has a sensitivity and specificity of 93% and 88% respectively.</li></li></ul><li>Right Atrial Rhythm<br />In right atrial rhythm the depolarization begins in the right atrium and spreads posteriorly and superiorly towards the left atrium (towards aVL). This inscribes a positive deflection (p wave) in aVL. <br />
In left atrial rhythm the depolarization of atria begins in the left atria and spreads anteriorly towards right atrium(in the direction of V1). This inscribes a positive deflection (p wave) in lead V1.</li></li></ul><li>The exceptions to the above criteria are ectopic foci with origin at the high crista terminalis (right atrial - near SA node) and impulse originating near the atrial septum.<br />
In our patient a positive p wave in V1 with a negative p in V6 is suggestive of a left atrial rhythm.<br />