Final answer:
With increasing severity of PAD, the Doppler ultrasound waveform becomes monophasic, reflecting reduced blood flow due to arterial obstruction. This contrasts with the triphasic waveform seen in healthy arterial flow.
Step-by-step explanation:
The question relates to the Doppler ultrasound waveform patterns observed in patients with Peripheral Arterial Disease (PAD). As PAD severity increases, the Doppler waveform shifts from a normal triphasic pattern (representing healthy arterial blood flow) to a reduced, monophasic waveform, indicating reduced blood flow and increased arterial obstruction. To clarify the other components mentioned in relation to an electrocardiogram (ECG), atrial depolarization is represented by the P wave, ventricular depolarization by the QRS complex, and ventricular repolarization by the T wave. Atrial repolarization is not seen on the ECG as it is masked by the QRS complex, representing ventricular depolarization.