No - not directly. Many microcontrollers have A/D converters built into them, but the ECG signal must be conditioned first before it can be digitized by an A/D converter. Op-amps are often used to build a differential amplifier to extract the small ECG signal from the large common-mode 50 or 60Hz noise coming from power lines all around the person or animal. The signal also needs to be further amplified to match the input signal range of the A/D converter for good vertical resolution. Some type of galvanic isolation is often used to improve the safety of the system, and additional high-pass and low-pass filtering is needed to block electrode offset voltages and out-of-band noise before it is digitized.
Do a search for ECG amplifier to learn more about these topics.
There is a life sciences discussion board here as well - there is a good deal of information on ECG processing on the board: http://forums.ni.com/ni/board?board.id=LifeScience
Steve
