by James J. Galligan, Ph.D., Associate Chair,
Department of Pharmacology and Toxicology

The popular and hyperkinetic TV pitchman Billy Mays recently died of an apparent heart attack.  Autopsy reports indicate that cocaine was present in his system, and this could have contributed to his fatal heart attack.  His family has disputed the toxicology report and the legal process should take its course here. However, this case does highlight the question: “How does cocaine cause heart attacks?”

Cocaine is a highly addictive drug because it acts on brain pathways responsible for the euphoric and rewarding feelings associate with cocaine use (the details of this can be the subject of future posts).  However, cocaine can also act as a local anesthetic drug, much like novacaine that you might received at the dentist’s office.  In fact, modern local anesthetics were developed to mimic the local anesthetic effects of cocaine, without producing the “euphoria” that makes cocaine such an easy drug to abuse.

What is a local anesthetic?  Most local anesthetics paralyze the sensory nerve fibers that supply tissues.  The dentist takes advantage of this with a local injection of novacaine before drilling a defective tooth.  The nerves that convey pain messages from the tooth to your brain are anesthetized by novacaine.  Theses pain messages require the electrical signals carried by sodium channels in the sensory nerve fibers. Novacaine and cocaine block these sodium channels so there is no electrical signal coming from the tooth and you continue to sit comfortably in the dentist chair while the drilling goes on.

What does all of this have to do with the heart?  Well the heart also generates electrical signals that occur in rhythms and these rhythms are required for the continuous and coordinated contractions of the heart muscle that are required for efficient pumping of blood.  The electrical rhythms require activity of sodium channels that can also be blocked by cocaine.  Most cocaine users do not experience heart problems.  However, those who might be predisposed to heart arrhythmias put themselves at much greater risk if they use cocaine.  Examples of people who might be at risk for arrhythmias include those who have high blood pressure or perhaps someone with cardiac hypertrophy.  Cardiac hypertrophy can occur in people with high blood pressure or those have had a previous heart attack.  However cardiac hypertrophy is not uncommon in highly trained athletes.  The enlarged heart is more susceptible to disturbances in heart rhythms and cocaine use in these individuals also puts them at great risk for heart attacks.

The lesson here is two fold.

  • Beware of cocaine, and
  • if you have high blood pressure,  take care of it before you put yourself at risk for a heart attack (with or without cocaine)