Successful transcatheter pulmonary valve implantation in a dog: first clinical report.

Transcatheter pulmonary valve (TPV) implantation is a therapeutic approach approved by the United States Food and Drug Administration for human patients with failing pulmonary conduits in 2010 and for failing bioprosthetic surgical pulmonary valves in 2017. We report here the first successful transcatheter implantation of a stented valve in a pulmonary position in a dog with congenital pulmonary valve disease. A 3-year-old, 10.9 kg, client-owned Beagle dog was referred for a follow-up visit after a percutaneous balloon valvuloplasty performed 22 months before for treatment of a severe type A valvular pulmonary stenosis. The Doppler-derived peak pressure gradient was 348 mmHg before the procedure and 66 mmHg 24 h after. The dog was lethargic. Echocardiography revealed a mild pulmonary stenosis (pressure gradient-43 mmHg), severe pulmonary regurgitation, and secondary severe right ventricular and right atrial dilation. Worsening of right heart dilation was observed 2 months later despite medical therapy. A TPV implantation was performed using a prestented Melody bovine jugular bioprosthetic valve. The dog recovered uneventfully and was discharged 10 days after the procedure. Right heart dilation resolved within 15 days. The dog was doing well 7 months after valve implantation. This case demonstrates that TPV implantation with a stented valve is technically feasible in dogs with severe pulmonary valve disease. Stringent postoperative care, with particular attention to thrombosis and infectious endocarditis, and appropriate sizing and positioning of the valve stent are keys to the success of this procedure.

Outcome of bioprosthetic valve replacement in dogs with tricuspid valve dysplasia.

OBJECTIVES: To describe the short-term and long-term outcome in dogs with tricuspid valve dysplasia undergoing tricuspid valve replacement under cardiopulmonary bypass. METHODS: Data were collected from the hospital records of all dogs that had undergone tricuspid valve replacement under cardiopulmonary bypass between 2006 and 2012. Dogs were considered candidates for tricuspid valve replacement if they had severe tricuspid valve regurgitation associated with clinical signs of cardiac compromise. RESULTS: Nine dogs of six different breeds were presented. Median age was 13 months (range 7 to 61 months), median weight 26·5 kg (range 9·7 to 59 kg). Eight bovine pericardial valves and one porcine aortic valve were used. One non-fatal intraoperative complication occurred. Complications during hospitalisation occurred in six dogs, four of which were fatal. Of the five dogs discharged, one presented dead due to haemothorax after minor trauma seven days later. The four remaining dogs survived a median of 533 days; all of these dogs received a bovine pericardial valve. CLINICAL SIGNIFICANCE: Based on our results, tricuspid valve replacement with bovine or porcine prosthetic valves is associated with a high incidence of complications.

Post-mortem evaluation of expanded polytetrafluoroethylene (ePTFE) used in mitral valve repair in dogs.

Mitral valve repair is one of the treatment options for mitral regurgitation. Expanded polytetrafluoroethylene (ePTFE) is a polymer that has been widely used in cardiovascular surgery. In this case series, we report the autopsy and histological findings in 6 dogs that underwent cardiopulmonary bypass for mitral annuloplasty using ePTFE sheets and chordoplasty using ePTFE sutures. From May 2005 to October 2009, 3 female and 3 male dogs with severe mitral regurgitation underwent mitral valve repair. This case series included 3 Cavalier King Charles spaniels, 2 Maltese, and 1 Shih Tzu. The survival period after surgery was 19-72 (35 ± 19) months. In all the cases, autopsy revealed that the ePTFE sheets and sutures were not damaged and well integrated into the surrounding highly differentiated, connective tissues. Low-power microscopy revealed that in all cases, the tissues surrounding the ePTFE sheet in the mitral valve annulus had almost completely been covered by granulation tissue. No inflammatory infiltrate or thrombogenesis was observed around the ePTFE in any of the cases. There was no evidence of reactive changes in the region surrounding the ePTFE. These results suggest that ePTFE has excellent tissue compatibility and durability and can be effectively used for canine mitral valve repair.

Bioprosthesis valve replacement in dogs with congenital tricuspid valve dysplasia: technique and outcome.

OBJECTIVE: To describe the surgical technique and report outcome of dogs undergoing bioprosthesis valve replacement for severe tricuspid regurgitation (TR) secondary to congenital tricuspid valve dysplasia (TVD). ANIMALS, MATERIALS AND METHODS: Twelve client-owned dogs (19-43 kg) with TVD underwent tricuspid valve replacement with a bovine pericardial or porcine aortic bioprosthesis with the aid of cardiopulmonary bypass. Anticoagulation with warfarin was maintained for 3 months after surgery and then discontinued. RESULTS: Ten of 12 (83.3%) dogs survived surgery and were discharged from the hospital. Seven dogs were alive with complete resolution of TR for a median period of 48 months (range 1-66 months) after surgery. Two dogs underwent euthanasia because of bioprosthesis failure due to inflammatory pannus at 10 and 13 months after surgery. Two dogs experienced valve thrombosis that was resolved by tissue plasminogen activator. One dog developed suspected endocarditis after surgery that was resolved with antibiotics. Serious cardiac complications included atrial fibrillation and flutter, right-to-left shunt through an uncorrected patent foramen ovale, complete atrioventricular block, and sudden cardiac arrest. Postoperative atrial fibrillation or flutter did not occur in 7 dogs treated prophylactically with oral amiodarone before surgery. CONCLUSIONS: Curative intermediate-term outcomes are possible in dogs undergoing open tricuspid valve replacement with a bioprosthesis. Prosthesis-related complications include inflammatory pannus, thrombosis, and endocarditis. Postoperative atrial fibrillation or flutter can be reduced or prevented by prophylactic preoperative treatment with amiodarone. Several identified complications are avoidable or can be reduced with increased awareness and experience with these techniques.

Design of a miniature tissue culture system to culture mouse heart valves.

Valvular heart disease is a leading cause of morbidity and mortality in adults but little is known about the underlying etiology. A better understanding of the genetic and hemodynamic mechanisms involved in growth and remodeling of heart valves during physiological and pathological conditions is needed for a better understanding of valvular heart disease. Here, we report the design of a miniature tissue culture system (MTCS) that allows the culture of mitral valves from perinatal to adult mice. The design of the MTCS is novel in that fine positioning and cannulation can be conducted with hearts of different sizes (perinatal to adult). Perfusion of the heart and hence, culture of the mitral valve in its natural position, occurs in a hydraulically sealed culture bath environment. Using the MTCS, we successfully cultured the mitral valve of adult mouse hearts for 3 days. Histological analysis indicated that the cultured valves remained viable and their extracellular matrix organization was similar to age-matched native valves. Gene expression could also be modified in cultured valves by perfusion with medium containing beta-galactosidase-expressing adenovirus. Thus, the MTCS is a new tool to study the genetic and hemodynamic mechanisms underlying the three-dimensional organization of the heart valves, which could provide insights in the pathology of valvular heart disease and be used in animal models for the development of tissue-engineered heart valves.

Short-term performance of mitral valve replacement with porcine bioprosthetic valves in dogs.

Porcine bioprosthetic valves cross-linked with glutaraldehyde and polyepoxy compound were newly developed for mitral valve replacement (MVR) in dogs. Five beagle dogs were performed a left thoracotomy and underwent MVR using the porcine bioprosthetic valves during cardiopulmonary bypass (CPB). A vein catheter inserted into right atrium and a vent catheter inserted into the right ventricle to drain. The hemodynamic conditions of CPB were excellent during surgery. The left atrial pressure was measured before and after MVR; there was no significant difference and it was normal. Thrombosis and the prosthetic valve regurgitation were not observed one week after MVR. Pressure half time (PHT) prolonged significantly (P<0.05) from 31.40 +/- 4.0 msec presurgery to 99.20 +/- 19.4 msec at seven days after MVR, although it indicated the normal range as the bioprosthetic valve. The symptom of the prosthetic valve failure was not observed. This study indicated that the MVR using porcine bioprosthetic valves under CPB might have been effective in dogs as a short-term evaluation.

Beating heart mitral valve replacement with a bovine pericardial bioprosthesis for treatment of mitral valve dysplasia in a Bull Terrier.

OBJECTIVES: To describe an open, beating heart surgical technique and use of a bovine pericardial prosthetic valve for mitral valve replacement (MVR) in the dog. STUDY DESIGN: Clinical case report. ANIMALS: Male Bull Terrier (17-month-old, 26 kg) with mitral valve dysplasia and severe regurgitation. METHODS: A bovine pericardial bioprosthesis was used to replace the mitral valve using an open beating heart surgical technique and cardiopulmonary bypass. RESULTS: Successful MVR was achieved using a beating heart technique. Mitral regurgitation resolved and cardiac performances improved (left ventricular end-diastolic diameter decreased from 57.6 to 48.7 mm, and left atrium/aorta ratio returned to almost normal, from 1.62 to 1.19). Cardiopulmonary by-pass time and total surgical duration were decreased compared with standard cardioplegic techniques. Surgical recovery was uneventful and on echocardiography 6 months later valve function was excellent. CONCLUSION: Considering the technique advantages (no cardiac arrest, ischemic reperfusion injury, and hypothermia, or the need for aortic dissection and cannulation for administration of cardioplegic solution), short-term mortality and morbidity may be reduced compared with standard cardioplegic techniques. CLINICAL RELEVANCE: Based on experience in this dog, beating heart mitral valvular replacement is a seemingly safe and viable option for the dog and bovine pericardial prosthesis may provide better long-term survival than mechanical prostheses.

Technique and outcome of mitral valve replacement in dogs.

Eight dogs with naturally occurring severe mitral regurgitation underwent mitral valve replacement with a mechanical valve prosthesis during cardiopulmonary bypass. Dogs received warfarin orally after surgery to maintain a prothrombin time-based international normalized ratio from 2.5 to 3.5. Seven dogs survived surgery. Left ventricular diastolic volume index decreased significantly from 206 +/- 91 mL/m2 before surgery to 121 +/- 47 mL/m2 after surgery. Left atrium-to-aorta ratio decreased significantly from 2.66 +/- 0.4 before surgery to 1.73 +/- 0.65 after surgery. Left ventricular systolic volume index was not significantly different after surgery (56 +/- 36 mL/m2), compared with before surgery (40 +/- 32 mL/m2). Median survival after surgery was 4.5 months (range, 0.75 months to 5.25 years). Six dogs died of confirmed or suspected thrombosis of the valve prosthesis. Dogs with severe mitral regurgitation tolerated mitral valve replacement well, but a high incidence of prosthetic valve thrombosis limited long-term outcome.

Successful prosthetic mitral valve implantation in pigs.

Clotting mechanisms, the coagulation cascade, platelet function, and platelet-leukocyte-endothelial cell interactions are all very similar in humans and pigs. Because of these similarities, the authors concluded that the pig would be an ideal model for the study of thromboembolism resulting from prosthetic heart valves. To date, they have successfully recovered a total of 11 pigs (52.9 +/- 8.1 kg), 3 with bioprosthetic valves and 8 with mechanical valves, all in the mitral position (25 mm od). The normal presence of high numbers of pulmonary endothelial macrophages and other unique aspects of porcine cardiovascular and pulmonary function dictate somewhat different surgical protocols than those normally used for human patients and ruminant species. Some of these special procedures include 1) crystalloid prime without the use of plasma volume expanders, especially those with a starch base; 2) pharmacologic protection against arrhythmias (lidocaine, 4 mg/kg); 3) special attention to adequate hypothermic cardioprotection during the time of cross-clamp; 4) the use of shock doses of corticosteroid (prednisolone sodium succinate, 0.5 mg/kg) before removal of the aortic cross-clamp; and 5) positive inotropic support (dopamine, 0.008 mg/kg) while weaning from cardiopulmonary bypass. Gamma camera images of 111In tagged autologous platelets 24 hours after surgery show most thrombi located on the sewing ring with fewer on the pledgets and anchor sutures. The latter observations were confirmed by quantification of platelet deposition using a gamma counter.

Surgical management of subvalvular aortic stenosis and mitral dysplasia in a golden retriever.

A 12-month-old neutered male golden retriever was presented with a history of lethargy and exercise intolerance. Clinical examination, electrocardiography, radiography and echocardiography supported a diagnosis of fixed subvalvular aortic stenosis with a Doppler pressure gradient of 77.5 mmHg. Surgical inspection also revealed gross structural abnormalities of the mitral valve consistent with mitral dysplasia. Intervention consisted of resection of the dysplastic mitral valve and the subvalvular aortic stenosis. The mitral valve was replaced with a bioprosthetic valve. Total cardiopulmonary bypass time was 65 minutes and aortic cross-clamp time was 55 minutes. A full recovery was made and 11 months postoperatively the aortic transvalvular gradient was 30 mmHg. At the time of writing, 12 months after surgery, the dog was clinically normal and requires no medication.

El Cerdo: de villano a gran amigo del hombre. "El cerdo de hoy"

La porcicultura ha evolucionado a tal manera, que el concepto acerca del cerdo de hace tres décadas como portador de enfermedades y poseer una carne con abundante cantidad de grasa nocivas para la salud humana, pasó a ser considerado hoy en día como un alimento seguro y una de las principales fuentes de proteínas, minerales y vitaminas que se conozcan. Los adelantos en la genética y alimentación porcina han permitido obtener animales con un contenido de colesterol similar a las consideradas carnes blancas. La similitud del cerdo en la fisiología y anatomía cardíaca con la del ser humano, han permitido considerar esta especie como uno de los modelos experimentales más ampliamente utilizados y sus aportes al conocimiento científico son incalculables. En nuestra institución desde hace varios años se ha venido trabajando y ganando experiencia en investigación con porcinos en diferentes áreas, tales como fuentes de prótesis valvulares biológicas principalmente para ser utilizadas en posición aórtica, manjeo anestésico, modelos de reestenosis coronaria mediante trauma con balón y Stents, neuro-intervensionismo con modelos de embolización endovascular cerebral y evaluación de hemosustitutos portadores de oxígeno en porcinos en modelos de bypass cardiovascular

Mitral valve replacement for the treatment of congenital mitral dysplasia in a bull terrier.

A 10-month-old entire male bull terrier was presented with a history of collapse on exercise. Clinical examination, electrocardiography, radiography and echocardiography all supported a diagnosis of mitral valve dysplasia. There was no evidence of congestive heart failure. Surgical intervention consisted of open resection of the dysplastic mitral valve and its replacement with a bioprosthetic valve. The procedure was performed through a median sternotomy and the dog was placed on to full cardiopulmonary bypass. Total cardiopulmonary bypass time was 70 minutes. A full recovery was made and at the time of writing (17 months postoperatively) the dog is clincally normal requiring no medication.

Tricuspid and mitral valvular disease: valve replacement.

Using the methods described, the author has performed AV-valve replacement surgery in seven clinical dogs with AV valve dysfunction. Two dogs received autologous tissue tricuspid valves, three dogs received autologous tissue mitral valves, one dog received a mechanical mitral prosthesis, and one dog received a mechanical mitral and autologous tricuspid prosthesis. The two dogs that received a tricuspid prosthesis recovered from surgery, one dog is normal nearly 3 years after valve replacement surgery, and the second dog was euthanized 3 weeks after replacement surgery because of complications related to other congenital cardiovascular defects (ie, pulmonary artery coartations). The dog that received the mechanical mitral valve prosthesis made a complete immediate postoperative recovery but died from hemorrhage complications related to a femoral artery catheter removal 3 days after surgery. Hemorrhage from the left atrium resulted in the death of one dog after implantation of a bioprosthetic mitral valve. Two dogs with mitral valve bioprostheses and one dog with a mitral and tricuspid valve replacement could not be weaned from the cardiopulmonary bypass pump, even with pharmacological support. Although the initial results in this small clinical trial have not been spectacular, it is apparent from the few clinical cases operated on that the equipment, supplies, and techniques have advanced sufficiently in veterinary surgical practice to perform AV-valve replacement surgery in companion animals. Prosthetic valves are available presently to perform such surgery even in small animal patients (5 kg). However, a significant obstacle that must be overcome before such techniques become routine is the selection of animal patients that have sufficient myocardial reserve to undergo valve replacement surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Mitral valve replacement in dogs. Surgical technique and postoperative management.

Although techniques for the perioperative management of patients undergoing mitral valve replacement have been well established in humans, the use of these techniques has not been widely accepted in veterinary practice. The purpose of this study is to demonstrate that low morbidity and mortality could be achieved in the dog undergoing mitral valve replacement. Nine mongrel dogs (25-45 kg body weight) were subject to left thoracotomy and mitral valve replacement using cardiopulmonary bypass (CPB). The average time on CPB was 1 hour with an aortic cross-clamping time of 40 minutes using chemically induced cardiac arrest. CPB was performed under conditions of moderate systemic hypothermia (28-30 degrees C) and hemodilution (hematocrit, 25-35%). Operative mortality was 22% (2/9) with one death from excessive bleeding and the other from cerebral air embolism. All other animals recovered and were clinically normal 3 weeks after surgery. The authors conclude that successful mitral valve replacement is possible in the large dog.

Mitral valve prosthesis for correction of mitral regurgitation in a dog.

Mitral regurgiation with atrial fibrillation in a 3-year-old St. Bernard dog was corrected by digitalization, placement of a mitral valve prosthesis, and direct current cardioversion. The atrial fibrillation eventually returned and became refractory to cardioversion.