Isamu Kanemoto(1,2*), Kippei Mihara(1,3) and Keiichi Sato(1,4)
1- Cardiac Surgery Team, Chayagasaka Animal Hospital, Nagoya, Japan
2- School of Medicine, Institute for Laboratory Animal Research, Nagoya University, Nagoya, Japan
3- Joint Graduate School of Veterinary Medicine, Kagoshima University, Kagoshima, Japan
4- School of Medicine, Nagoya University, Nagoya, Japan
In human medicine, in the past, open-heart techniques for low-bodyweight children and newborn babies with congenital heart disease were more difficult than high-bodyweight adults. In toy- and small-breed dogs with mitral regurgitation (MR), an acquired heart disease, these techniques are more difficult to perform than for congenital heart diseases in young medium-sized or large dogs because of old age and low body weight. Therefore, improved open-heart techniques and mitral valve surgery for severe MR in older toy- and small-breed dogs are essential. Through our surface-cooling hypothermia (sHT) studies, we designed a new, improved open-heart method, namely, “the low-flow cardiopulmonary bypass (CPB) combined with deep sHT in toy- and small-breed dogs (Japan method)”; sHT was later replaced by blood-cooling hypothermia. At the same time, we devised a new, improved mitral valve plasty (MVP) applicable to severe MR, instead of mitral valve replacement (MVR), in toy- and small-breed dogs. This MVP technique was combined with artificial chordal reconstruction, semi-circular suture annuloplasty, and direct scallop-suture valvuloplasty. These MVP techniques are simple, durable, and lead to good long-term QOL in toy- and small-breed dogs. This review highlights the benefits of our improved CPB and MVP techniques (Japan method) for severe MR in toy-and small-breed dogs, which have led to a high success rate for MVP in severe clinical MR cases in Japan. It may further contribute to the development of more robust techniques for MR in toy- and small-breed dogs. This also represents the first comprehensive review of the history of open-heart surgery, CPB techniques, and MVP methods for MR in toy- and small-breed dogs.
Keywords: Direct scallop-suture valvuloplasty, Mitral regurgitation, Mitral valve plasty, Open-heart techniques, Toy and small dogs.