Cardiovascular changes after bone marrow transplantation in dogs with mucopolysaccharidosis I.

Five dogs with mucopolysaccharidosis I, 3 of which had been treated with bone marrow transplantation (BMT), were evaluated for 20 months with electrocardiography, thoracic radiography, and M-mode and 2-dimensional echocardiography. Treated and untreated (control) dogs had widened P waves on ECG. Thoracic radiographs remained normal for all dogs throughout the study. Thickening of the mitral valve was observed on echocardiograms of dogs in both groups, but the untreated dogs appeared to have thicker valves. Concentrations of glycosaminoglycans in the mitral valves and myocardium were higher in control dogs than in treated dogs. Markedly large aortic root diameters were observed on echocardiograms in both untreated dogs, but aortic root diameters remained normal in treated dogs. Echocardiography, but not electrocardiography, was useful in monitoring heart enlargement in each dog. Dogs treated with BMT generally had less severe cardiac changes and slower disease progression than control dogs.