A total artificial heart is a medical device that replaces the two main pumping chambers of a failing human heart. It is used when both ventricles can no longer move enough blood to keep the body alive. The device connects to the major blood vessels and pushes blood to the lungs and the rest of the body.
It matters because continuous circulation delivers oxygen and removes carbon dioxide and waste from tissues.
Understanding Medical Technology: The Total Artificial Heart
A total artificial heart works as part of a larger system, not as a small object working alone inside the chest. Flexible membranes divide each artificial ventricle into a blood side and a drive side. An external driver moves air or another gas into the drive side.
This pushes the membrane and forces blood forward. When the pressure is released, the chamber fills again. Mechanical valves act like one way doors.
They must open at the correct pressure and shut quickly to prevent backward flow. The remaining upper chambers of the patient’s heart can still receive blood from the veins and pass it into the device.
The two pumps must stay closely matched. If the right side moves much more blood than the left side, fluid can build up in the lungs. If the left side moves much more, it may not have enough blood returning from the lungs to fill properly.
Clinicians adjust the pumping rate and the amount moved in each beat while watching blood pressure, oxygen levels, urine production, and other signs of organ function. The body changes its demands during sleep, standing, exercise, fever, or stress.
A useful idea is that flow depends on both the pump and the resistance in blood vessels. Narrower vessels create more resistance, so the pump must work harder to maintain flow.
This treatment is often used as a bridge to a heart transplant. It can give a person time when donor heart surgery is planned but no donor heart is available yet. It can require long hospital care, especially at first.
The external driver, tubing, and skin exit sites need careful daily attention. Germs can enter where lines pass through the skin, causing serious infection. Blood touching artificial surfaces can form clots.
Patients usually need medicines that reduce clotting, but these medicines increase bleeding risk. Teams watch for signs of a clot, bleeding, infection, device alarms, and changes in circulation. A device can support life, yet it does not remove every medical risk.
When learning this topic, separate the job of moving blood from the job of adding oxygen. The artificial heart moves blood, while the lungs still add oxygen and remove carbon dioxide. Compare it with a left ventricular assist device, which supports only one pumping side and leaves the patient’s own heart in place.
Think of the circulation as a loop with pumps, valves, flexible vessels, and resistance. Pressure is not the same as flow.
A high pressure reading does not guarantee that every tissue receives enough blood. The key engineering challenge is safe, reliable pumping that responds to a changing human body.
Key Facts
- Cardiac output is the blood flow per minute: CO = stroke volume x heart rate.
- A total artificial heart replaces both ventricles, not the atria or the blood vessels.
- The right pump sends oxygen-poor blood to the lungs through the pulmonary artery.
- The left pump sends oxygen-rich blood to the body through the aorta.
- Blood pressure is produced when the pumps apply force to blood inside flexible chambers or sacs.
- Power and control signals usually come from an external driver connected through lines that pass through the skin.
Vocabulary
- Total artificial heart
- A total artificial heart is a device that replaces both lower pumping chambers of the heart to maintain blood circulation.
- Ventricle
- A ventricle is a lower heart chamber that pumps blood out of the heart.
- Cardiac output
- Cardiac output is the volume of blood pumped by the heart or artificial heart each minute.
- Aorta
- The aorta is the large artery that carries oxygen-rich blood from the left side of the heart to the body.
- External driver
- An external driver is the outside power and control unit that keeps some artificial heart pumps moving.
Common Mistakes to Avoid
- Thinking a total artificial heart is the same as a pacemaker is wrong because a pacemaker sends electrical signals to a natural heart, while a total artificial heart replaces the heart's pumping ventricles.
- Labeling the pulmonary artery as carrying oxygen-rich blood is wrong because it carries oxygen-poor blood from the right pump to the lungs.
- Forgetting that the device needs continuous power is wrong because a stopped pump would quickly stop circulation and threaten the brain and other organs.
- Using only heart rate to describe blood flow is wrong because total flow also depends on stroke volume, so CO = stroke volume x heart rate.
Practice Questions
- 1 A total artificial heart ejects 70 mL of blood per beat from the left pump and beats 90 times per minute. What is the cardiac output in L/min?
- 2 An external battery can supply 180 Wh of energy, and the driver uses 12 W of power. How many hours can the battery run the device if energy losses are ignored?
- 3 Explain why a total artificial heart must have separate right and left pumping paths instead of one single pump for all blood flow.