Ventricular septal defect

From Dog
Gross heart specimen of a dog which died from Ehrlichia spp vegetative endocarditis. Postmortem examination revealed a perforating ventricular septal defect[1]

Ventricular septal defect (VSD) is a congenital disease of dogs characterized by a hunting of blood from the left to right chambers of the heart.

This condition in dogs is relatively rare and constitutes about 7% of congenital heart diseases[2]. Some are considered innocent in the respect of self-resolving with age, but many are large and worsen as the dog matures[3].

Although most VSDs are a defect with communication between left and right ventricles, abnormal VSDs can occur as left ventricular-right atrial communications, known collectively as Gerbode defects[4].

Clinical signs are normally seen in young dogs (1 - 2 years of age) but can present at an older age with symptoms of generalized weakness, exercise intolerance, syncope, abdominal swelling associated with ascites and pale mucus membranes. A cough may be present intermittently.

A tentative diagnosis can be established by auscultation of a holosystolic heart murmur and radiographic evidence of cardiomegaly but definitive diagnosis requires use of M-mode and Doppler echocardiography.

ECGs usually reveal varying degrees of left or right bundle branch block.

Echocardiographs usually elucidate the septal defect and often shows concurrent right ventricular hypertrophy[5].

A differential diagnosis would include atrial septal defect[6], double-chambered right ventricle[7], hyperthyroidism, cardiomyopathy, Duchenne muscular dystrophy, endocarditis, mitral valve endocardiosis, other causes of congestive heart failure and infections with Dirofilaria spp.

Treatment is usually conservative, with management of the secondary congestive heart failure, but surgical correction can be performed at specialty referral centers using cardiopulmonary bypass[8]. New surgical techniques are also reported such as a pan-nitinol occluder device for transcatheter closure of the defect[9].

References

  1. Ramírez GA et al (2003) Left ventricular outflow tract-right atrial communication (Gerbode type defect) associated with bacterial endocarditis in a dog. Vet Pathol 40(5):579-582
  2. Oliveira P et al (2011) Retrospective review of congenital heart disease in 976 dogs. J Vet Intern Med 25(3):477-483
  3. Rausch WP & Keene BW (2003) Spontaneous resolution of an isolated ventricular septal defect in a dog. J Am Vet Med Assoc 223(2):219-220
  4. Gerbode F et al (1958) Syndrome of left ventricular-right atrial shunt. Ann Surg 148:433–466
  5. Tou SP et al (2011) Pulmonary atresia and ventricular septal defect with aortopulmonary collaterals in an adult dog. J Vet Cardiol 13(4):271-275
  6. Guglielmini C et al (2002) Atrial septal defect in five dogs. J Small Anim Pract 43(7):317-322
  7. Fukushima R et al (2011) Epidemiological and morphological studies of double-chambered right ventricle in dogs. J Vet Med Sci 73(10):1287-1293
  8. Yamano S et al (2011) Surgical repair of a complete endocardial cushion defect in a dog. Vet Surg 40(4):408-412
  9. Ding ZR et al (2009) A new pan-nitinol occluder for transcatheter closure of ventricular septal defects in a canine model. J Interv Cardiol 22(2):191-198