OBJECTIVES

Congenital tricuspid valve malformation (CTVM) includes apical displacement of the tricuspid valve annulus (Ebstein's malformation, EM), and a variety of right atrioventricular valve abnormalities classified as tricuspid valve dysplasia (TD), i.e., abnormal leaflets, underdevelopment of papillary muscles or chordae tendinae, and adherence of the septal leaflet to the interventricular septum. CTVM usually results in tricuspid regurgitation which may lead to right atrial and ventricular enlargement, and then to right-sided heart failure. The objectives of this retrospective study were first to document the predisposition parameters for CTVM in small animal medicine; secondly, to assess the clinical signs and echo-Doppler findings in a population of dogs and cats with a diagnosis of CTVM and to determine their influence on survival time.

MATERIALS

Dogs and cats were recruited between March 1995 and March 2002 from the Department of Cardiology of the National Veterinary School of Alfort (France). All animals underwent a complete clinical examination. The inclusion criteria included the presence of tricuspid regurgitation (confirmed with Doppler mode) associated with one or more of the following: focal or diffuse thickening of tricuspid valve leaflets, hypoplasia of right chordae tendinae, abnormal form of right papillary muscles, incomplete separation of valve components from the ventricular wall. The distributions of breeds and genders in the studied population with CTVM and in the overall hospital population were compared using odds ratios.

RESULTS

50 cases were diagnosed with CTVM, 36 dogs (53% males, 47% females) and 14 cats (64% males, 36% females). 24 dogs and 14 cats showed TD and 12 dogs, EM. Concurrent congenital cardiac abnormalities, most often mitral dysplasia, were identified in 77% dogs and in all cats. 62% of cases were diagnosed in animals younger than 1 year old. Comparison with the small animal hospital population (85250 animals: 50637 dogs and 34613 cats) revealed no gender predisposition for CTVM. Conversely, Boxers were predisposed for TD (17% of cases) and Labrador retrievers for EM (67% of cases). Purebred cats (50%) showed predisposition to TD, especially Chartreux (28% of cases). No functional symptom was observed in 41% of cases. Intensity of heart murmur was not correlated to CTVM gravity. Higher mortality was found for animals with EM (33%, mean age at death: 26±2 months), however EM was identified in dogs as old as 7 years of age.

CONCLUSION

This study demonstrates that EM and TD have specific characteristics: not only echocardiographic abnormalities, but also breed and species predisposition, symptomatology, and sometimes evolution may be very different according to the tricuspid malformation. Our results also show that animals with CTVM may live with few symptoms for several years, even if right heart enlargement is already present at the time of diagnosis.