Even if precious minutes have gone by, it is not too late to attempt cardiopulmonary resuscitation, commonly called CPR, on a suspected victim of cardiac arrest due to heart disease.

Dr. Martin Kohn, director of New York University Medical Center's residency program in emergency medicine, said that if a person has no detectable pulse for three to five minutes, it does not automatically mean resuscitation is impossible.But chances for survival without brain damage may improve if a victim of cardiac arrest is immediately helped - by someone with CPR training - until professional help arrives.

CPR training and certification is offered regularly by local health facilities and by chapters of the American Red Cross.

During cardiac arrest, which may have several causes such as a heart attack or a rhythm disorder (arrhythmia), the heart muscle stops beating or beats ineffectively, cutting off blood circulation to the brain and other organs.

"There may still be blood circulating in the brain that would not be enough to maintain consciousness, but careful and rapid evaluation is necessary to determine if CPR is appropriate," Kohn said.

People trained in CPR first check to see if the patient has a pulse and is breathing. Kohn cautioned that the application of CPR to patients with cardiac arrest from non-cardiac related causes may not be helpful to the patient.

"Sometimes the collapse can be due to obstruction of the breathing passages, in which case certain techniques, such as the Heimlich maneuver, can restore breathing," Kohn advised.

If there is no sign of airway obstruction, the patient's pulse should then be checked by applying finger pressure to either side of the neck just under the jaw area.

"When someone collapses, you don't know if it's cardiac arrest, a seizure or something else. It may even be an episode of low blood sugar," he said.

If the patient is neither breathing nor has a pulse, help starts with an immediate telephone call for emergency assistance, usually the 911 emergency number. Try to provide as much information as possible about the patient's condition.

Kohn added that if a person is having suspected cardiac problems due to heart disease but has not lost consciousness, call for professional help as quickly as possible. Speed in this instance is the critical factor.