Each cell in the average human body contains 23 pairs of chromosomes, with four telomeres on each pair. Telomeres cover the end of the chromosome, protecting it from deterioration or fusion with adjacent chromosomes. While there is a length range for classifying a healthy telomere, researchers found, for the first time ever, that people with heart failure have shorter telomeres within the cells that make up the heart muscle (known as cardiomyocytes).