A 50-year-old woman suffered from bilateral bronchiectasis and chronic pseudomonas lung infection for many years. Her condition has recently deteriorated and she is in the medical ICU in severe respiratory failure:

• Sinus tachycardia, 106/min
• Left atrial enlargement
• Right axis deviation

Comment: Prominent negative P waves in V1 to V3 may occasionally be seen in patients with chronic lung disease and pulmonary emphysema in the absence of left atrial enlargement. Because of the low diaphragm, the right chest leads are abnormally high in relation to the atria, and the mean P vector projects on the negative side of V1-V3. (T-C Chou, Electrocardiography in Clinical Practice, 4th ed., Saunders 1996, page 32)