Double-chambered right ventricle

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Angiogram showing DCRV[1]

Double-chambered right ventricle (DCRV) is an uncommon congenital disease of dogs characterized by juvenile-onset right-sided congestive heart failure and sudden death[2].

This congenital defect occurs primarily in large-breed dogs and has not been frequently categorized until recently and was previously described as a subvalvular pulmonic stenosis.

Double-chambered right ventricle is a form of septated right ventricle caused by the presence of abnormally located or hypertrophied muscular bands which divide the right ventricle cavity into a proximal and a distal chamber. These bands can be located at the cardiac apex or attached to the right ventricle[3]. The defect obstructs flow through the ventricle and causes hypertrophy of the inflow but not outflow portion of the right ventricle. The malformation is often accompanied by tricuspid regurgitation

Concurrent congenital disease also occur with this condition, including ventricular septal defect, tricuspid valve dysplasia, pulmonary valve stenosis and subaortic stenosis[4].

The defect causes clinical and pathophysiologic signs similar to those of congenital pulmonic stenosis in dogs but has distinct diagnostic features[5]. Affected dogs are asymptomatic, but clinical signs are commonly reported in young dogs (from 12 weeks of age) with generalized weakness, exercise intolerance, syncope, pale mucus membranes and progressive ascites. A cough may be present intermittently.

A tentative diagnosis can be established by auscultation of a holosystolic ejection murmur at the left base close to the sternum and radiographic evidence of cardiomegaly and pulmonary edema, but definitive diagnosis requires use of M-mode and Doppler echocardiography or angiocardiography[6].

Echocardiographs usually shows right ventricular hypertrophy with an abrupt transition to normal-appearing ventricular outflow tract. Doppler echocardiography usually reveals turbulent flow in the right ventricular outflow tract and a pressure gradient across the defect.

A differential diagnosis would include ventricular septal defect[7], atrial septal defect[8], hyperthyroidism, cardiomyopathy, Duchenne muscular dystrophy, endocarditis, mitral valve endocardiosis, other causes of congestive heart failure and infections with Dirofilaria spp.

Treatment is usually conservative in cases with mild clinical signs, with management of the secondary congestive heart failure.

Surgical correction can be performed at specialty referral centers via cardiopulmonary bypass to resect the fibromuscular bands via right ventriculotomy[9].

References

  1. Medscape
  2. López-Alvarez J et al (2011) Balloon dilation of an imperforate cor triatriatum dexter in a Golden Retriever with concurrent double-chambered right ventricle and subsequent evaluation by cardiac magnetic resonance imaging. J Vet Cardiol 13(3):211-218
  3. Fukushima R et al (2011) Epidemiological and morphological studies of double-chambered right ventricle in dogs. J Vet Med Sci 73(10):1287-1293
  4. Koie H et al (2000) Double-chambered right ventricle in a dog. J Vet Med Sci 62(6):651-653
  5. Martin JM et al (2002) Surgical correction of double-chambered right ventricle in dogs. J Am Vet Med Assoc 220(6):770-774
  6. Willard MD & Eyster GE (1981) Double-chambered right ventricle in two dogs. J Am Vet Med Assoc 178(5):486-488
  7. Guglielmini C et al (2002) Atrial septal defect in five dogs. J Small Anim Pract 43(7):317-322
  8. Fukushima R et al (2011) Epidemiological and morphological studies of double-chambered right ventricle in dogs. J Vet Med Sci 73(10):1287-1293
  9. Tanaka R et al (2006) Surgical management of a double-chambered right ventricle and chylothorax in a Labrador retriever. J Small Anim Pract 47(7):405-408