A heart bypass pump, more accurately known as a cardiopulmonary bypass (CPB) machine or heart-lung machine, doesn't directly "pump" the heart. Instead, it takes over the functions of the heart and lungs temporarily during open-heart surgery. Here's how it works:
Understanding the CPB Circuit
The CPB machine acts as an artificial circulatory system, ensuring the body continues to receive oxygenated blood while the surgeon operates on the heart.
Key Functions
| Function | Description |
|---|---|
| Blood Diversion | Venous blood, which is deoxygenated, is diverted from the patient’s body before it reaches the heart. |
| Oxygenation | This diverted blood is then passed through an oxygenator, where it picks up fresh oxygen and releases carbon dioxide. |
| Filtration | The oxygenated blood is filtered to remove any harmful particles or air bubbles. |
| Return to Arterial System | Finally, the now oxygenated and filtered blood is pumped back into the patient's arterial system, allowing it to circulate and deliver oxygen to the body’s tissues and organs while the heart is stopped. |
Detailed Breakdown
- Venous Cannulation: Blood is drained from the body through tubes (cannulas) inserted into large veins, typically near the right atrium.
- Oxygenation Process: The blood is directed to the oxygenator. This device uses either a membrane or bubble system to ensure oxygen diffuses into the blood, and carbon dioxide diffuses out.
- Blood Pumping: A pump in the CPB circuit then propels the now oxygenated blood through a filter before returning it to the body.
- Arterial Cannulation: The oxygenated blood returns to the body via a cannula, typically inserted into a large artery like the aorta. This directs the blood into the systemic circulation to perfuse all organs.
Why is this necessary?
- Surgical Access: Stopping the heart allows surgeons to operate in a still, bloodless field, enabling them to perform intricate procedures like bypass grafting or valve replacement.
- Maintaining Organ Perfusion: The CPB machine ensures that vital organs receive the necessary oxygenated blood to function while the heart is stopped.
- Temporary Support: The CPB machine is a temporary solution to keep the body alive during surgery. Once the heart surgery is completed, the machine's support is gradually reduced and the heart resumes its function.
As our reference highlights, "The CPB circuit, or heart-lung machine, diverts venous blood from the patient, oxygenates and filters it, and then returns it to the arterial system, ensuring continuous perfusion of vital organs while the heart is stopped." This detailed process makes the complex heart surgery possible.
