Polygenic inheritance can be explained as Mendelian inheritance at many loci, resulting in a trait which is normally-distributed. If n is the number of involved loci, then the coefficients of the binomial expansion of (a + b) 2n will give the frequency of distribution of all n allele combinations.
Once the pacemaker is implanted, the leads carry signals back from the heart. The pulse generator reads these signals and the batteries send electrical impulses to the heart to help pace it. Most pacemakers can sense the heart's rhythm and turn themselves off when the heartbeat is above a certain level. They will turn on again when the heartbeat is too slow. These types of pacemakers are called demand pacemakers.
If you have a pacemaker and become terminally ill with a condition unrelated to your heart, such as cancer, it's possible that your pacemaker could prolong the process of dying. Doctors and researchers have varied opinions on turning off a pacemaker in end-of-life situations.