Pigs as Models to Test Cardiovascular Devices

Pigs as laboratory animals are used in preclinical studies aimed at developing medical devices for cardiac surgery. The anatomy of the cardiovascular system of these animals has been well studied and acknowledged as suitable for use and the testing of new cardiovascular devices developed for humans. However, there are no morphometric characteristics of the aortic root and thoraco-abdominal part of porcine aorta. This can lead to difficulties in experimental surgery and even result in the death of experimental animals due to the mismatch in the size of the implantable devices. Thus, such information is essential to enhance the efficiency of surgical technologies used for eliminating aortic pathologies in their various sections. The purpose of our research is to study the anatomy of the aorta in mini pigs and to assess whether the size, age, and sex of the animals affect the size of the main structures in their aortas. In addition, we attempted to compare the results obtained by transesophageal echocardiography (TEE) and angiography. We studied 28 laboratory mini pigs, dividing them into three groups by body weight (40-70 kg, 71-90 kg, and 90 kg). We did not find any relationship between the external somatometric characteristics of the animals and the size of their aortas. Animals have individual anatomical variability in their cardiovascular systems, which means that they need to be examined in terms of preoperative planning by any available method-echocardiography, angiography, or multispiral computed tomography (CT).

Transcatheter Mitral Valve Repair and Replacement: What's on the Horizon?

There are more than 4 million people affected by mitral regurgitation in both the United States and Europe. Prior to the last decade the only options for treatment of MR were medical therapy and open-heart surgery which left many high risk patients with little option once medically optimized. However, we saw a flood in innovative transcatheter mitral valve interventions. As the technologies are refined these new approaches are considerably less invasive and for some high-risk patients may represent a superior option to conventional open-heart surgery. There are 3 main approaches currently being considered for transcatheter mitral valve repair, edge to edge repair, indirect annuloplasty and direct annuloplasty. There have also been large advancements in recent years in transcatheter replacement of the mitral valve. Although many of these devices are under investigation still, we sought to examine the current state of innovative transcatheter mitral valve technologies.

Local Tolerability and Performance Evaluation in Domestic Pigs of a Fractional Radiofrequency Device for Dermatologic Treatment

Information on the safety of energy-based dermatological surgical devices in domestic pigs, and fractional radiofrequency (RF) devices in particular, is very limited. The aim of this study was to evaluate in a GLP-compliant study in domestic pigs the local reaction and performance of a novel fractional RF device. Five female domestic pigs were subjected to fractional RF pulses, using different energy and pulse durations and depth of penetration of the pulses. The animals were evaluated clinically and histologically at different time points (days 0, 1, 3, 7, and 14) postenergy exposure. There were no microscopic or macroscopic local adverse effects in any tested power settings, and there was time-related progressive healing, reaching complete macroscopic and microscopic healing by 7 days postapplication. As expected, there was power-related progressive increase in the incidence of ablation (destruction of skin tissue by vaporization) and coagulative necrosis of the dermis from low to high power setting. This comprehensive study, using multiple power settings (both ablative and coagulative) and several time points, will be of benefit for future studies evaluating new fractional RF devices.

Histology Strategies for Medical Implants and Interventional Device Studies

Histology of medical devices poses a variety of unique challenges. Comprehensive histologic assessment of medical devices often requires spatial context and high-quality retention of the device–tissue interface. However, the composition of many medical devices is often not amenable to traditional paraffin embedding and thus alternative specialized methodologies such as hard resin embedding must be used. Hard resin embedding requires specialized laboratory technical expertise and equipment, and the fixation techniques and resin composition used markedly impact the feasibility of immunohistochemistry. For the continuity of spatial context during histologic evaluation, additional imaging methods such as macrophotography, radiography, micro-Computerized Tomography (microCT), or magnetic resonance imaging (MRI) can be used to guide sectioning and to complement histologic findings. Although standardized approaches are scarce for medical devices, important considerations specific to medical device histology are discussed, including general specimen preparation, special considerations for devices by organ system, and the challenges of immunohistochemistry. Histologic preparation of medical devices must be thoughtful, thorough, and tailored to achieve optimal histologic outcomes for complex, valuable, and often limited implant specimens.

Cutaneous Candidiasis in a Gottingen Minipig: A Potential Pitfall in Preclinical Studies

The Göttingen minipig is often used in preclinical toxicity studies. Therefore, knowledge of spontaneously occurring pathologies is important to differentiate them from test drug-related effects. We report on a Göttingen minipig, which developed exudating widespread dermatitis during a preclinical toxicity study with a subcutaneously injected drug. The lesions were resistant to topical and oral antibacterial medications. Skin cultures were positive for Candida albicans, and treatment was changed to topical antifungal cream with quick resolution of the skin lesions. Cutaneous candidiasis in pigs has been rarely reported in the literature, and this is the first report on such condition in preclinical toxicity studies. Knowledge of this condition, which is not drug related, is important, especially in toxicity studies involving subcutaneous injections that are commonly accompanied by inflammatory skin reactions.

Trauma as a Cause for Hepatopathy in Newborn Göttingen Minipigs

Routine husbandry procedures during animal toxicity studies can result in incidental pathological changes. We report on trauma-induced hepatopathy in newborn Göttingen minipigs. Sixty-four neonatal minipigs were allocated to 13- and 26-week treatment arms. There was a 4-week recovery period for both arms. The animals were divided into 2 treatment groups and a vehicle group and were dosed 3 times daily by direct oral administration using a syringe. During the feeding procedure in the first weeks, the animals had to be handled firmly. After 13 weeks, randomly distributed foci of degeneration/necrosis and focal congestion and/or hemorrhage were found in the livers of several animals from all groups. Reduced incidence and severity were evident in the recovery phase, and the lesions were absent after 26 weeks. These changes were considered as related to the manual handling of the animals. Knowledge of these findings is crucial for interpretation of studies utilizing newborn minipigs.