Double-chambered right ventricle in two dogs.

In 2 dogs (3 and 8 months old), double-chambered right ventricle was diagnosed by selective angiocardiography. In 1 dog, the systolic pressure in the outflow tract portion of the right ventricle and in the main pulmonary artery was 13 mm of Hg, whereas the systolic pressure in the right ventricle proximal to a constricting muscular ring was 80 mm of Hg. The absence of a valvular pressure gradient and the appearance of normal valves at surgery indicated that the right ventricular outflow obstruction was a congenital lesion. The 67-mm of Hg pressure gradient suggested the need for resection of the obstruction. The defect was corrected surgically and the dog was clinically normal when examined 1 1/2 years later. The 2nd dog was not considered for corrective surgery because of a clinically insignificant gradient in the right ventricular outflow tract. When the dog was examined at 11 months of age, the cardiac silhouette was bilaterally enlarged. However, inasmuch as the dog had not experienced any exercise intolerance or weakness and the electrocardiogram was normal, further diagnostic and therapeutic work was not done. When the dog was examined at 20 months of age, it appeared healthy.