pacemaker

Pacemaker – a small device that is placed in the chest or abdomen to help control abnormal heart rhythms. This device uses electrical pulses to prompt the heart to beat at a normal rate.

Pacemakers are used to treat arrhythmias (ah-RITH-me-ahs). 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.

A pacemaker consists of a battery, a computerized generator, and wires with sensors at their tips. (The sensors are called electrodes.) The battery powers the generator, and both are surrounded by a thin metal box. The wires connect the generator to the heart.

A pacemaker helps monitor and control heartbeat. The electrodes detect the heart’s electrical activity and send data through the wires to the computer in the generator. If the heart rhythm is abnormal, the computer will direct the generator to send electrical pulses to your heart. The pulses travel through the wires to reach the heart.

Newer pacemakers can monitor blood temperature, breathing, and other factors. They also can adjust the heart rate to changes in activity.

The pacemaker’s computer also records heart’s electrical activity and heart rhythm. These recordings can be used to adjust the pacemaker so it works better for the individual.

What’s the problem?
Engineers are taught to follow very specific steps to solve problems and create new products and services. The process is the same for all engineering projects. For really big projects, they can spend years gathering information and creating designs. For small problems, they may just think through the process to come up with an answer. Either way, they are following the [[[Engineering Design Process]].

Ask
The first important factor that any engineer will want to know is the program objectives. Program objectives may address size, performance (speed), cost, improved function, etc. The second question will be in what time frame this has to be done.

Since pacemakers already exist, we assume we want to make a new and improved version. So what are the objectives for a new pacemaker?

• We probably want it to be smaller in size, and to use less power (extend battery life).
• Maybe we want a new, better battery technology.
• Perhaps we want to add the ability for external control in emergencies.

And we want to accomplish this within 18 months (fairly typical for the electronics industry). At first, you may think this last objective is
not very important. However, it impacts everything you do!!

An objective of 18 months means you have to select from recently developed or existing electronic building blocks (like a processor, memory chips, wi-fi devices). You do not have time to wait for whole new things to be developed – which often takes 18-24 months by themselves. So, let’s write these down. Objectives:

• Smaller, more compact in size (new case design)
• Lower power
• Better battery technology
• External control feature
• Start manufacturing within 18 months

Imagine
Now that we have established some goals and objectives we can go to work. First we need to “research” each facet of our program. We will consult other engineers who are specialists or experts in the circuit technology for pacemakers. We ask them what is new or will shortly be new in this area. How much performance improvement can we expect? How much smaller will the units be, and what will be the battery requirements?

We will approach battery developers and ask about new battery technologies, what size will they be, when will they be available and at what cost. We will need to know what technologies might provide external control capabilities (Wi-Fi network?). Is there any potential for providing power via radio waves and re-charging the batteries?

Plan
Once we have some ideas on the technology availability we can put together a development plan. We have to define what we are going to develop and what it will take. For example, a new smaller unit will require a new case and perhaps case materials. The electronics, battery, cables all have to be able to fit in the case. And we need to devise a plan and tools for manufacturing this new product.

The development plan will address:

• Assumptions on basic new technologies that will be used.
• An outline of what will have to be developed
• A list of suppliers for things to be purchased
• A manufacturing plan and tool set
• Checkpoints for when specific parts of the program have to be finished so that the end objectives will be met. Most parts of the program can be done in parallel, but not all.
• Resources that will be needed (usually the number of man-months required and the degree of expertise i.e. engineer, technician, administrative, etc.)

Create
Now all we have to do is Create and Implement the Plan.

• When is it needed (a schedule)
• Cost objective

Devise a Plan to carry out

• Start with what we already know (don’t re-invent the wheel!)
• Identify what new things are needed
• Develop new technologies and integrate with existing ones
• Prototype and evaluate
• Document – file patents, prepare specifications
• Prepare a manufacturing and quality plan
• Introduce to manufacturing

Improve
Identify areas for improvement and prioritize them

• Engineer improvements

That’s Engineering

• electrical circuits – to deliver the correct amount of electric current from the battery through the capacitors to stimulate the heart when needed
• metallurgy – the composition of the metal case that is small and light as well as bio-non-reactive for housing the electrical components surgically implanted into the patient’s chest
• embedded systems – takes the input from the sensors detecting heart beats, determine when there is a problem and direct the circuity to deliver electric current as necessary

Engineering ideas

• battery, computerized generator, sensors, electrodes

Do it
Here are some challenges for you to work on…

• research the history of pacemakers

Learn more…

• Latest smaller pacemakers – New cardiac devices are small enough to be delivered through blood vessels into the heart.
• What’s a Pacemaker – National Institutes of Health