Cardioplegia is the intentional and temporary cessation of cardiac activity, primarily used in cardiac surgery.
The most common procedure for accomplishing asystole is infusing cold crystalloid cardioplegia into the coronary circulation. This process is considered the most successful because it protects the myocardium, or heart muscle, from damage . In most cases, the patient is first exposed to mild hypothermia (34 degrees celsius). Then an iced (4 degrees celsius) solution of dextrose, potassium chloride, and other ingredients  is introduced into coronary circulation via specialized cannulae.
When solution is introduced into the aortic root (with an aortic cross-clamp on the distal aorta to limit systemic circulation), this is called Antegrade Cardioplegia. When introduced into the coronary sinus it is called Retrograde Cardioplegia.