As a medical professional with expertise in cardiology, I can provide you with an explanation of what a notched P wave signifies in an electrocardiogram (ECG). A notched P wave, also known as a "double hump" or "biphasic" P wave, can be indicative of certain cardiac conditions. When you see a P wave with a notch or a split appearance, it suggests that there is a delay or enlargement in the atrial depolarization process. This can be a normal variant, but it can also be associated with conditions such as left atrial enlargement (LAE), which is an enlargement of the left atrium of the heart. To diagnose LAE from a notched P wave, you would typically look for specific criteria. If the two peaks of the notched P wave are separated by a distance equivalent to one small box (usually representing 40 milliseconds) or more on the ECG grid, it can be considered diagnostic of LAE. Additionally, a biphasic P wave is considered indicative of LAE if the downward portion of the P wave is one box or larger in both depth and length. It's important to note that while a notched P wave can be a sign of LAE, it is not definitive on its own and should be interpreted in the context of the patient's overall clinical presentation and other diagnostic findings. read more >>

A ��double hump�� or notched P wave is diagnostic of LAE if the peaks are one small box or more apart. A biphasic P wave indicates left atrial enlargement if the downward portion of the P wave is one box or larger in both depth and length.read more >>