Final answer:
True, both wandering atrial pacemaker and multifocal atrial tachycardia are characterized by having at least three different P wave shapes on an ECG, indicating multiple atrial pacemaking sites.
Step-by-step explanation:
The statement is true. Both wandering atrial pacemaker and multifocal atrial tachycardia are characterized by having at least three different morphologies of P waves on an electrocardiogram (ECG). The P wave represents atrial depolarization, which is when the atria of the heart are electrically activated to contract. In these conditions, multiple areas within the atria become pacemakers, thereby causing the variability in P wave shapes. This is unlike the normal heart rhythm where the sinoatrial (SA) node is the sole pacemaker, resulting in uniform P wave appearances on an ECG.
The QRS complex signifies ventricular depolarization, and the T wave represents ventricular repolarization. However, atrial repolarization is masked by the larger electrical signal of ventricular depolarization represented by the QRS complex on the ECG, and thus it isn't typically seen and doesn't affect the diagnosis of wandering atrial pacemaker or multifocal atrial tachycardia.