Biomedical Engineering Implants BTY100-Lec# 6.2 Biomedical Engineering Implants

OUTLINE Implants Artificial Pacemaker Cochlear Implant Dental Implant

Implants An implant is a kind of medical device made to replace and act as a missing biological structure. Examples include: artificial pacemaker and cochlear implants. Implants are man-made devices, in contrast to a transplant, which is a transplanted biomedical tissue.

Identify the implant!!!! What is the Location of this implant in the body???

Artificial cardiac pacemaker A pacemaker is a medical device that uses electrical impulses(delivered by electrodes) to contract the heart muscles, and regulate the beating of the heart. The primary purpose of a pacemaker is to maintain an adequate heart rate he primary purpose of a pacemaker is to maintain an adequate heart rate Natural Pacemaker: The contraction of heart muscle in all animals is initiated by electrical impulses. The rate at which these impulses fire controls the heart rate. The cells that create these rhythmical impulses are called pacemaker cells, and they directly control the heart rate. The sinoatrial node (SA node) is a group of cells positioned on the wall of the right atrium.

Artificial cardiac pacemaker??? Pacemakers are used to treat arrhythmias . Arrhythmias are problems with the rate or rhythm of the heartbeat. During an arrhythmia, the heart can beat : too fast, too slow, or with an irregular rhythm. During an arrhythmia, the heart may not be able to pump enough blood to the body. This can cause symptoms such as fatigue (tiredness), shortness of breath, or fainting. Severe arrhythmias can damage the body's vital organs and may even cause loss of consciousness or death. A pacemaker also can help a person who has abnormal heart rhythms resume a more active lifestyle.

COMPONENTS Artificial pacemaker devices generally include the following components: Pulse generator :A thin metal case which contains the power source producing the electrical impulses of the pacemaker. In addition, the pulse generator contains a small computer processor that can be programmed to set the rate of the pacemaker, the energy output, and various other parameters. The pulse generator for most modern permanent pacemakers weighs one to two ounces.

COMPONENTS Flexible insulated wires: carry electrical impulses from the generator to the heart muscle and relay information concerning the heart's natural activities back to the pacemaker. There may be several such wires, or leads, placed within the heart, most commonly in the right atrium and right ventricle. One or more electrodes at the tips of the leads transmit electrical impulses to the heart muscle when needed.

WORKING

Cochlear Implant The human ear is made up of thousands of hair cells (present in cochlea), which when working properly are stimulated by sound, and then begin to vibrate. Then these vibrations are converted into nerve impulses which are taken up to the brain to be interpreted via auditory nerve. In people having deafness, the hair cells are unable to function, therefore severing the path of sound to the brain.

How the normal ear works? http://www.childrensuniversity.manchester.ac.uk/interactives/science/brainandsenses/ear/

Cochlear Implants Muscles can change electrical energy into mechanical energy, Electrodes can give off such electrical impulses, stimulating surrounding nerves. This allows for signals to by-pass damaged parts, such as hair cells or the ear, yet still stimulate the nerve. A lead of electrodes is implanted in the ear to replicate the function of hair cells and stimulate the cochlea. The implanted lead contains anywhere from 1 to 22 electrodes, each being stimulated by different frequencies and pitches. These electrodes then stimulate the nerves and then send it to the brain via the hearing nerve.

Cochlear Implants An implant has the following parts: A microphone, which picks up sound from the environment. A speech processor, which selects and arranges sounds picked up by the microphone. A transmitter and receiver/stimulator, which receive signals from the speech processor and convert them into electric impulses. An electrode array, which is a group of electrodes that collects the impulses from the stimulator and sends them to different regions of the auditory nerve.

Dental Implants Difference between Prosthetic and Implant!! is a surgical component that interfaces with the bone of the jaw to support a dental prosthesis such as a crown, denture. The basis for modern dental implants is a biologic process called osseointegration where materials, such as titanium, form an intimate bond to bone. The implant fixture is first placed, so that it is likely to osseointegrate, then a dental prosthetic is added. A variable amount of healing time is required for osseointegration before either the dental prosthetic (a tooth, bridge or denture) is attached to the implant. A natural tooth consists of a crown (the part you see above the gum), and the root (the part hidden under the gum). It is the root in the jawbone that actually holds the natural tooth in place. A dental implant is a small man-made titanium fixture that serves as a replacement for the root portion of a missing natural tooth. Titanium is used because it is the most compatible with our human body. The dental implant is placed in the bone of the upper or lower jaw and functions as an anchor for the replacement tooth. After the bone has grown around the implant, implants can hold a crown, bridge or overdenture just like roots hold natural teeth in place. Implants provide additional support where teeth are missing without putting forces onto remaining natural teeth. They may be used to support the replacement of a single missing tooth or a complete functional set for individuals who have lost many or all of their teeth. Dental Implant Prosthetic

The final prosthetic can be either: The prerequisites to long-term success of dental implants are healthy bone and Gums. The final prosthetic can be either: fixed: where a person cannot remove the denture or teeth from their mouth or Removable: where they can remove the prosthetic. Removable Fixed

Risks and Complications divided into 3 categories: those that occur during surgery (excessive bleeding or nerve injury) those that occur in the first six months (infection and failure to osseointegrate) those that occur long-term ( mechanical failures). In the presence of healthy tissues, a well integrated implant with appropriate biomechanical loads can have long term success rates of 93 to 98 percent for the fixture and 10 to 15 year lifespans for the prosthetic teeth.

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