1. E LECTRONIC P ACEMAKER Dancho Grigorios B070049EC

3. All heart cells, muscle and conducting tissue, are capable of generating electrical impulses that can trigger the heart to beat. The SAN - "heart's pacemaker" SAN - 60-70 beats /minute. Increases its' rate due to stimuli like exercise, fever… AVN - 40-60 beats/minute. The Bundle of HIS 30-40 beats/minute. Ventricular muscle cells 20-30 beats/minute. The AVN and remaining parts of the conducting system are less capable of increasing heart rate due to stimuli previously mentioned than the SAN.

4. P ACEMAKER Electrical device inserted under the skin to control the heart rate

6. P ACEMAKER IMPLANTATION Minimally invasive surgery-local anesthesia- area under collar bone-45 minutes Small incision -3 inches long- a “pocket” is fashioned in the tissue overlying the muscle. The leads are inserted through a vein near the site of the pocket, and advanced into the heart using fluoroscopy (x-rays) for guidance. The leads are then attached to the generator, the generator is placed in the pocket, and the incision is closed. Pacemakers can be programmed with a handheld device that communicates with the pacemaker through the skin.

9. W HEN DO WE NEED A PACEMAKER A very slow heart rate leading to symptoms of fatigue, weakness and dizziness. Heart rates below 35-40 beats a minute for a prolonged period usually cause problems due to not enough blood flow to vital organs. A diagnosis found with an electrocardiogram that indicates a potential for sudden drastic drops in the heart rate. Injury to the heart muscle that may occur after a heart attack that interferes with your heart’s ability to control the heart rate. To prevent the heart rate from dropping too low when you are taking certain medications to treat a very fast heart rate.

10. A pacemaker in its simplest configuration is essentially a battery- operated digital pulse generator.

11. P ACEMAKER COMPONENTS The major components are: Lead wire Electronic pulsing circuit Battery Electronic sensing circuit

12. L EAD The lead can cause a failure due to metal fatigue, introduced by the motion and beating of the heart. To avoid such fatigue, the lead may be constructed by winding platinum ribbon around polyester yarn. Each lead may have three such wires for redundancy.

13. B ATTERY AND ITS LIFETIME Because the pacemaker is battery-operated and surgically implanted, battery lifetime is one of the most important considerations. Lithium iodide cells which can last as long as 15 years is used now a days. The lifetime of battery is determined The stimulus requirements, The current caused by the pacemaker circuitry.

14. B ATTERY AND ITS LIFETIME The use of complementary metal-oxide semiconductor (CMOS) integrated circuits has dramatically reduced the current drain The stimulus requirements are determined by physiology and cannot be reduced effectively.

15. As is usually the case with physiological stimuli, there is a curve of stimulus intensity versus duration associated with the physiological response of heart depolarization V s (V) Time, T D (ms) The figure shows the stimulus voltage, V s, at the tissue-electrode interface

16. It has a stimulus duration T D, measured in milliseconds. Such curves depend upon the electrode-heart resistance, R H, which may range from 100 to 1400 .

17. The value of R H may change over time because of tissue scarring at the electrode-tissue interface. In order to produce a stimulus pulse, it is necessary to deliver energy to the electrode with a pacemaker circuit.

18. A digital pulse has a voltage V s that may be made variable to allow adjustments in the energy, E P, delivered by the pacemaker to the heart during each pulse.

19. During the pulse duration, T D, the stimulus voltage drives energy into the heart. When the pulse is OFF, it causes an energy drain given by V s I D T, where T is the time period between successive pulses, and I D is the current drain on the battery when the pulse is OFF.

20. Therefore, the energy delivered by the pacemaker during each pulse is given as

21. EXAMPLE Using the figure, compute the energy per pulse when the pacemaker pulse width is 0.5 ms, the circuit-current drain is 1  A, the heart-electrode resistance is 200 , and the heart rate is 70 bpm.

22. SOLUTION From the figure, V s = 1.8 V. Also, T = (60/70) s. Then, Thus the energy used for each pulse is EP = 9.643  J/pulse

23. The electrode-muscle contact can change after a time because of (1) polarization by ionic current flow; (2) tissue and scar growth; or (3) mechanical motion of the heart.

24. A symptom of such change may be an increased electrode impedance. The problem may be fixed by increasing the pulse voltage from the pacemaker or by lengthening its duration. Loss of contact altogether may require surgical reimplantation.

25. Implantable batteries are usually encased in metal. If they become too hot, such as when shorted, the case may rupture. Pacemaker design should ensure that the case is strong enough to contain such a rupture and prevent toxic materials from entering the body of the patient.

26. A SYNCHRONOUS PACEMAKER The asynchronous pacemaker produces a pulse at a preset rate, for example 70 bpm, and delivers pulses to the heart regardless of the heart’s natural beating tendency and independent of the QRS complex. This pacemaker does not increase the heart rate in response to the body demand for more blood during exertion.

27. P- WAVE SYNCHRONOUS PACEMAKER The SA node depolarization responds to body demands through the vagus nerve and hormones transported in the blood. In a P-wave synchronous pacemaker, the SA node triggers the pacer, which in turn drives the ventricle. It is used when the AV node is blocked because of disease.

28. D EMAND PACEMAKER If the pulse rate falls below a predetermined minimum, the pacemaker will turn on and provide the heart a stimulus.

30. Another type of demand pacemaker uses a piezoelectric sensor shielded inside the pacemaker casing. When this sensor is slightly stressed or bent by the patient’s body activity, the pacemaker will automatically increase or decrease its rate.

31. L IVING WITH PACEMAKER Do not have a Magnetic Resonance Imaging (MRI) test, electric cauterization, dental procedures using electrical appliances. Keep the cellular phone at least 6 inches away from the Heart Pacemaker. Ensure that physician adjusts and checks Heart Pacemaker whenever a new medication is prescribed. Check periodically to ensure that Heart Pacemaker is functioning correctly and that the batteries have not worn out. As Heart Pacemaker are made of metal, they may set the alarm off when passing through metal detectors at the airport.

32. I SSUES Unauthorized third parties-reprogram the devices??? Costly Reuse removing hardware from a corpse for re-implantation in an otherwise healthy person??? materials discarded by the wealthy are redistributed to others???

33. R EFERENCE http://your-doctor.com/healthinfocenter/medical- conditions/cardiovascular/conductiontutorial.htm l www.justmeans.com en.wikipedia.org/wiki/Artificial_pacemaker http://indicure.com/treatments/cardiac- procedure/invasive-cardiology/pacemaker- implantation.htm faculty.etsu.edu/blanton/Pacemaker.ppt

34. T HANK YOU