CALL 9-11 or 415-553-8090 in SF for an emergency.

Automated External Defibrillators (AED) can save lives in the critical period between heart attack and professional emergency care.

Many of the tech shuttles carry AEDs.

Here is a map of some public AED locations.  This map is community maintained and may not be accurate.  Embedded here:

View SF Fire App AED Verification in a larger map

As Wikipedia puts it:

"An automated external defibrillator (AED) is a portable electronic device that automatically diagnoses the life-threatening cardiac arrhythmias of ventricular fibrillation and ventricular tachycardia in a patient,[1] and is able to treat them through defibrillation, the application of electrical therapy which stops the arrhythmia, allowing the heart to reestablish an effective rhythm."