<unk>  can result from increased pressure in the pulmonary artery.   A P wave >2.5 mm in leads II, III and aVF 
or a P wave >1.5 mm in lead V1 indicates<unk> . Despite the increase in the height of the P wave, the width of the P wave does not change.  Sometimes these large P waves can be referred to as Himalayan P waves.
Right atrial enlargement
Overriding aorta
Over-riding of the aorta
Left ventricular hypertrophy
Cardiomegaly
Right ventricular hypertrophy
Pericardial calcification
Subcutaneous emphysema