Characteristic peaked<unk> of cor pulmonale Peaked<unk>  (> 0.25 mV) suggest right atrial enlargement, cor pulmonale, (P pulmonale rhythm), but have a low predictive value (~20%). A<unk> with increased amplitude can indicate hypokalemia. It can also indicate right atrial enlargement. A<unk> with decreased amplitude can indicate hyperkalemia.<unk> changes in left and right atrial hypertrophy Bifid<unk>  (known as P mitrale) indicate left-atrial abnormality - e.g. dilatation or hypertrophy. If at least three different shaped<unk>  can be seen in a given ECG lead tracing, this implies that even if one of them arises from the SA node, at least two others are arising elsewhere. This is taken as evidence of multiple (i.e. at least two) ectopic foci, and is called multifocal (or more correctly, multiform) atrial rhythm if the rate is ≤100) or multifocal atrial tachycardia if the rate is over 100. This appears particularly commonly in exacerbations of chronic obstructive lung disease. If the baseline has a totally irregular form, this suggests fibrillatory waves of atrial fibrillation or possibly artefact; a saw tooth shaped baseline suggests the flutter waves of atrial flutter. With either of these rhythms, if the ventricular rate is fast, the fibrillatory or flutter waves can easily be misinterpreted as<unk> . Absence of the<unk> with a flat baseline may indicate: * Fine atrial fibrillation * Sinoatrial arrest (with a secondary escape rhythm) If<unk>  are not clearly delineated in the surface ECG, a Lewis lead may be used to better visualize<unk> .
P wave 
J wave
QRS complex
U wave
Delta wave
T wave
ST segment
PR interval