Glossary

Heart rate (HR) is a measure of the number of heart beats per minute (bpm).  The average resting human heart rate is about 70 bpm for adult males and 75 bmp for adult females, however anywhere from 60 bpm to 100 bpm is considered a normal resting heart rate.  Heart rate varies significantly between individuals based on fitness, age and genetics.  Endurance athletes often have very low resting heart rates.  Heart rate can be measured by monitoring one’s pulse.  Pulse measurement can be achieved using specialized medical devices, or by simply pressing one’s finger against an artery (typically on the wrist or the neck).

Hypertrophic Cardiomyopathy (HCM) is a genetic disorder of the heart characterized by increased thickness (hypertrophy) of the wall of the left ventricle, the largest of the four chambers of the heart.  The disease can present at any time in life.  It is the leading cause of sudden death in athletes and young people.  It is inherited in an autosomal dominant manner.  Men and women with HCM stand a 50-50 chance of transmitting the HCM gene to each of their children.

Measurement of the thickness of the left ventricle wall can predict who is most at risk for HMC.  The test is done by echocardiography, a routine ultrasound test of the heart.  Persons with a maximum wall thickness less than three-quarters of an inch (19mm) are virtually free of risk for fatal cardiac arrest over the next 20 years whereas those with a wall thickness more than 1.2 inches (30mm) have a 40% chance of fatal cardiac arrest during that time period.  Patients in danger can be fitted with implantable defibrillators.