Which condition causes a notched and wide P wave greater than 0.1 second?

A notched and wide P wave greater than 0.1 second is characteristic of left atrial enlargement. This enlargement occurs due to increased pressure or volume overload in the left atrium, which can be caused by several factors, including mitral valve disease, chronic hypertension, or heart failure.

When the left atrium is enlarged, the electrical conduction through the atrium is altered, resulting in prolonged depolarization and the characteristic notching of the P wave seen on the electrocardiogram (ECG). This prolonged duration is a direct reflection of the increased mass of the atrial tissue and its changing electrical properties.

Understanding the morphology of the P wave can provide significant insight into the underlying structural changes in the heart, particularly in conditions affecting atrial size and function. In the context of the options given, left atrial enlargement is the only condition that consistently results in this specific P wave abnormality, thereby distinguishing it from conditions like right atrial enlargement, myocardial infarction, or cardiomyopathy, which do not typically produce a notched and wide P wave of this form.