Cannulation of the cardiac lymphatic system in swine

OBJECTIVE

Cardiac lymph is the most direct medium for analyzing metabological changes in the myocardial cell. Currently, dogs are the animals used for investigation of myocardial lymphatic function. However, questions arise when comparing and interpreting the human system to the experimental model, since the dog coronary anatomy is different from human anatomy and pulmonary lymph contamination is found in up to 81% of the cases. Swine, having similar coronary anatomy to humans, are a proven model for cardiovascular research. The purpose of this study was to investigate the cardiac lymphatic anatomy of the swine and to develop a reliable cannulation technique to collect the lymph.

METHODS AND RESULTS

The lymphatic anatomy of 60 pigs was studied and classified and a new technique for lymphatic cannulation was developed. The cannulation success rate was 55%. In addition, no pulmonary lymph contamination was found at the cannulation site.

CONCLUSION

We conclude that porcine myocardial lymphatics can be successfully cannulated for the investigation of myocardial lymphatic function.

The history and development of the implantable hearing aid

Implantable hearing aids have an interesting and colorful history. These devices have usually been investigational, but this has changed. Currently, several implantable devices are available for ongoing clinical trials in humans. They have promise in providing improved hearing in certain cases of conductive, mixed, and sensorineural hearing loss.

Newer technique of laryngeal reinnervation: superior laryngeal nerve (motor branch) as a driver of the posterior cricoarytenoid muscle

This report analyzes the experience gained using two different techniques to reinnervate the paralyzed vocal cord. In the neurotization group, the superior laryngeal nerve (SLN) motor branch-cricothyroid muscle pedicle was used to reinnervate the posterior cricoarytenoid muscle. In the direct nerve anastomosis group, the SLN was anastomosed to the abductor branch of the recurrent laryngeal nerve (RLN), and the ansa hypoglossi (AH) to the adductor branch of the RLN. A third group of animals (control) had the right RLN sectioned without any anastomosis. About 5 to 6 months postoperatively the animals were killed painlessly and evaluated. The neurotization group revealed vocal fold mobilization on the right side to have an average of about half of the mobility of the left, normal side. After the RLN and SLN on the left were severed as well as the AH bilaterally, the vocal cord mobility was reduced to about one fourth. The direct nerve anastomosis group showed about fourfold less vocal cord mobility than the neurotization group. After the SLN, RLN, and AH were severed bilaterally, the control group showed no vocal cord mobility. The neurotization technique has been selected for further experimentation in human adults.

Electromagnetic implantable middle ear hearing device of the ossicular-stimulating type: principles, designs, and experiments

This report analyzes the principles, describes designs, and discusses the advantages and disadvantages of different types of implantable middle ear hearing devices. Preliminary acute experiments using an electromagnetic transducer for an implantable hearing device of the ossicular-stimulating type were performed in cats. A miniature samarium cobalt rare earth magnet was cemented on the head of the stapes. An electromagnetic coil powered either by direct wiring or by telemetry was used to stimulate the stapes. The performance of the system was evaluated by electrophysiologic assessment of hearing (brain stem evoked response potentials). The findings showed that the device is functional with good "implant gain" (35 dB average) and consumes reasonably low current (0.6 mA) with telemetry. Further investigation is necessary in order to develop an implantable middle ear hearing device with successful clinical application.