1. Problems of creating physiologically matched artificial cardiac pacemakers Sergei Ovsjanski Tallinn University of Technology 2009

2. What is a pacemaker? Artificial pacemakers are a two-part electrical system that includes a pulse generator (pacemaker) and one or two leads which deliver impulses to the heart. The leads also carry signals back from the heart. By "reading" these signals, the pulse generator is able to monitor the heart's activity and respond appropriately. A pacemaker helps to pace the heart when the natural rate is too slow to pump enough blood to the body (bradycardia).

3. Pacing Systems Pulse generator Sensing and Pacing lead

4. Pulse generator Main elements: Power source – provide the energy required for the operation of the pacemaker Memory (RAM/ROM) to store data for diagnostic purposes Antenna. Monitors relevant heart data and sends it, for example, to doctor Microprocessor – controls all operations Pulse generator is responsible for generating the pulse at the proper time based on events sensed

5. Pacing Lead The generator is connected to heart through the tiny wires called leads. Leads deliver the pulse to its destination in the heart, sense and carry back information to the pulse generator. Each lead has an electrode on its tip. That tip actually burrows into heart wall Connector Lead Body Active Fixation Mechanism Tip Electrode

6. Fixation Mechanisms Good contact with the heart wall. Achieve best results in pulse pacing of the heart

7. Electrode Effective interface between two systems, physiology and electronics, can be done with electrode Material used for electrode tips is titanium Electrode housing is made from silicone rubbers Steroids needed to prevent inflammation process Inflammation – process when, human body attempts to isolate a foreign object (est. põletik)

8. How a healthy heart works? The heart is a double pump that circulates blood around the body. It has four chambers. The upper right chamber (right atrium) and lower right chamber (right ventricle) take in deoxygenated blood from the body and send it to the lungs. The upper left chamber (left atrium) and the lower left chamber (left ventricle) take in oxygenated blood from the lungs and send it around the body. The ventricles do all the pumping. The nervous system is responsible for the heart rate and coordinating the heart's pumping action

9. How does a pacemaker take over heart beat? The pacer's electrical pulses travel through leads to heart. The pulses are timed to flow at regular intervals just like heart's natural electrical signals would. Pacer has 2 functions: pacing and sensing ( The third function is programming ) Pacing Pacer sends electrical signals to heart through pacing leads. Each electrical signal is called a pacing pulse. The pacing pulse begins heart beat Sensing Leads send information about heart's electrical system back to the pacer. This allows the pacer not to interfere with a natural, healthy heart beat Sensing Functions: - Level detection (amplitude) - Filter (band-pass filter) - Amplifier

10. Picture illustrates how pacemaker is connected to the heart and take control over heart`s beat

11. Types of artificial cardiac pacemakers Unipolar system Single chamber - only one chamber is regulated Bipolar system Dual chamber - two leads are used.

12. Implantation procedure The procedure is usually done under local anaesthesia The pulse generator is implanted under the skin The leads are inserted using x- ray control, via a vein found in this area, and positioned in the appropriate right sided heart chamber The leads are tested before the pulse generator is attached

13. Programming Pacemakers have many programmable functions that can be done with a special programmer. Unfortunately there is no universal programmer and each manufacturer provides programmers that will work only with their pacemakers

14. Living with an artificial cardiac pacemaker A person with an artificial cardiac pacemaker can live a normal life and can still do everyday activities. Most pacemakers last longer than five years. Before the pacemaker fails, a battery depletion indicator suggests that the pacemaker should be replaced. This is again performed under local anaesthesia.

15. How does magnet application affect a pacemaker? Magnet application disables the sensing amplifier, causing it to pace asynchronously. It is recommended that patients with a pacemaker keep at least 15 cm away from possible sources of magnetic interference, e.g. mobile phones, magnetic pain therapy, stereo speakers

16. First pacemakers The battery operated pacemaker by Lillehei and Bakken (1957) First totally implantable pacemaker by Senning (1958) A model of Albert Hyman’s Pacemaker (1931)

17. Thank you for attention Questions?