Which item is NOT listed as affecting signal quality and noise?

• A. Amplifier
• B. Filtering
• C. Cables
• D. Pacemaker leads

Answer: (D)

Understanding signal quality in electrophysiology recordings comes down to how the signal is captured and transmitted. The amplifier matters because it sets gain and contributes input-referred noise; the filtering shapes which frequencies are kept and which are suppressed, removing much of the surrounding noise while preserving the cardiac signal; and the cables (with their shielding and impedance) influence how faithfully the signal is carried to the recorder without picking up interference.

Pacemaker leads, while important for therapy and capable of causing pacing or sensing artifacts, are not part of the recording chain's controllable factors in this context. They belong to the implanted device system and aren’t typically listed as a primary determinant of signal quality and noise in the lab’s measurement setup.