Bleeding Hearts: Creative Alternatives To Animal Testing

Challenging procedures in microsurgery require dexterity and skill, both of which are built through extensive practice. As the complexity of surgical techniques and instrumentation expands, so does the challenge of finding appropriate models for surgical trainees to practice on. The criteria for a good training model is one that mimics (1) the anatomy and, (2) the types of crises seen during live surgery. In vascular surgery, which concerns itself with blood vessels, mimicking the conditions of live surgery through a model is particularly challenging. The properties of the human blood vessel system, particularly its ability to hemorrhage, pulse, and fill with blood, is difficult to replicate. Live animals are often used to train surgical residents for vascular surgery, because animals have a blood vessel system that can bleed, pulse, and fill similar to how human blood vessels would during live surgery. 

While live anesthetized animals are the most capable of mimicking the conditions of live surgery, the use of animal models poses problems for both surgical trainees and animal advocates. On the animal advocacy end, there are understandable concerns about animal suffering and mistreatment. However, this paper focuses on the concerns for surgical trainees, which are equally relevant if we are to eliminate the use of animals for surgical training. This paper suggests there is a unique new method available for surgical training that overcomes the ethical and practical drawbacks of live animal experimentation. 

According to the authors, animal models for vascular microsurgery training are wasteful. Eight to ten rats are needed for a trainee to practice various vascular exercises and there is a time constraint on how long these rats are viable as training models. Furthermore, there are limits to the number of exercises that can be performed on these animals, because their anatomy is different from human anatomy, which is what the trainee will have to deal with during live surgery. Thus, even though live anesthetized animals provide bleeding, pulsation, and soft, oozing tissues as humans may do during live surgery, their anatomy is different, they are only useful for a short period of time, and it is costly to procure and maintain a supply of live animals for training. 

The authors of this paper propose and test an alternative model that accurately represents the human anatomy, simulates life-like conditions (bleeding, pulsation, liquid filling vessels, and soft, oozing tissues), and is more sustainable for trainees. The model system for vascular microsurgery training in this paper is a human cadaver. Because the cadaver is human, it exactly replicates the anatomy that trainees will encounter in live surgery, meeting criteria #1 for a good training model. In regards to criteria #2, the cadaver is given life-like vascular properties by connecting the arteries to an external liquid source. Dark red liquid mimicking blood is pumped into the arteries from a pressure bag. The pressure bag is connected to a pump. A controlled pressure can be transmitted through the pump into the bag, injecting liquid into the arteries in a pulsating fashion. 

This system, which relies on the cadaver for anatomical likeness and on external pumps and bags to simulate the mechanical reality of live surgery, can be used for a diversity of surgical exercises. This paper explored a handful of procedures related to neurovascular surgery, or management of blood vessels in the brain. The authors detail the usefulness of the model in craniotomy (incision into the skull), vascular dissection (incision into the vessels to explore their structure or removal of arteries also known as endarterectomy), vascular suturing and anastomosis (stitching vessels closed or making new connections between vessels), resection (removal) of artificial tumors, and neuroendoscopy (insertion of a camera into the brain). 

The authors were particularly interested in the application of this model to training surgeons for cerebral aneurysms. Aneurysms are when the arteries balloon out due to weakening of the arterial wall. Aneurysms are prone to rupture, which can cause blood from arteries to leak out. This is a great concern during surgery, because it can lead to hemorrhage or high-pressure bleeding. Hemostasis, or management of bleeding, is difficult to practice outside of live anesthetized animals which, until this paper, were the only models capable of mimicking these crisis conditions. However, using a human cadaver, the authors of this paper were able to create an artificial aneurysm by replacing part of the artery wall with a portion of a vein, which is weaker than an artery. By artificially weakening the wall, they created an aneurysm that could be punctured to simulate aneurysm rupture, allowing the trainee to practice crisis management. Demonstrating the usefulness of their model for aneurysm management was a huge step, because it shows how this cadaver model can realistically train surgeons for high-stakes problems better than animal models could. 

Overall, this study shows there are creative ways to repurpose human cadavers to do the job that live anesthetized animals had previously been used for. In using human cadavers for surgical training, trainees not only gain the advantage of working on human anatomy, but they are also able to perform a wider range of exercises, practice for an extended period of time, and ensure accuracy and reliability in the types of surgical situations they are exposed to. Although intended for a biomedical audience, this study marks an important step for animal advocacy as well, because it shows animal models are not necessary and may even be less useful than cadaver models for practicing surgery. Although there are still shortcomings to this technique, these researchers show that there are ways the medical community can avoid sacrificing animals and still stay true to its purpose to save human beings. 

From this study, it is clear that the goals of surgeons and the goals of animal advocates are both noble in their own right and need not be mutually exclusive. We can be proactive in preventing both human and animal suffering, if we deploy the ingenuity and creativity that modern medicine is lauded for.

Note: This is a summary of an older study. For further developments being made to reduce the number of animals used in science, please see that section of our library.