• Question: what is a pace maker in more detail

    Asked by anon-178538 to Emma, Jordan, Kate, Lucy, Pankaj, Samuel on 12 Jun 2018.
    • Photo: Samuel Vennin

      Samuel Vennin answered on 12 Jun 2018:

      The first thing to understand here is how the heart works. It is a pump surrounded by a muscle that we call the myocardium. This muscle contracts to ejects the blood inside the heart out, and relaxes to let blood in. What makes this muscle contracts and relaxes is an electrical signal that propagates through it.

      It happens sometimes that this eletrical signal cannot propagate well (weak signal or obstacles to its propagation). In those cases, the heart won’t be able to beat normally and for example, won’t eject enough blood to keep the person body working. To prevent that from happening and ensure that the heart beats normally, we use a pacemaker.

      A pacemaker is a small box that we put inside the body, close to the heart, and that has wires we can tie to the heart. These wires will send an electrical signal to the heart and make it beat properly. To know when the pacemaker must send the signal, it continuously measure the patient heart rate and detect when it is not beating fast enough.

      The video below might be a bit complicated but it explains well how the heart works and how pacemakers can help:

    • Photo: Emma Wellham

      Emma Wellham answered on 13 Jun 2018:

      Samuel has given a very in-depth description, so there is not much I can add!

      But yes, the heart uses electrical signals to make the heart contract or beat. This beat pushes blood around the body so that the other organs receive the oxygen and nutrients that they need. In some people, the sinus node, or the ‘natural pacemaker’ a small group of cells in the top chamber of your heart, which normally produces the electrical signals your heart needs to beat, doesn’t make enough of them, so the heart doesn’t beat as many times as it should, and the other organs don’t receive enough blood, making the patient feel unwell. In other cases, the sinus node is working fine, but there is a block between the top chambers and the bottom chambers, and the electrical signal can’t go from top to bottom.

      A pacemaker is a small battery with some wires that can sit in either the top or bottom chambers of the heart, or in some cases both! They watch the hearts electrical activity, and if it sees that the sinus node hasn’t worked, it produces the electrical signal in the top chamber that the heart needs to beat. The other wire sits in the bottom chamber and watches to see if the electrical signal has come through from the top chamber, if it doesn’t see the signal, it produces an electrical signal in a bottom chamber to make the heart beat!

      If I won the money, i’d like to make a circuit with a pacemaker and some light bulbs, which would sit inside a wooden model of a heart, with the pacemaker as the battery. Then, when the pacemaker would normally try to send an electrical signal to the heart, the correct lightbulbs would light up. If you programmed the pacemaker to increase the heart rate, the lightbulbs would flash faster. It would make it much easier to show how a pacemaker worked!

Comments