Page 145 - Small Animal Internal Medicine, 6th Edition

CHAPTER 5 Congenital Cardiac Disease 117

consists of frequent small, semisolid, or liquid meals eaten OTHER VASCULAR ANOMALIES
in an upright position. This feeding method may be neces- A number of venous anomalies have been described, but
VetBooks.ir sary indefinitely. Persistent regurgitation occurs in some most are not clinically relevant. The persistent left cranial
vena cava is a fetal venous remnant that courses lateral to the
dogs despite successful surgery, suggesting a permanent
left AV groove and empties into the coronary sinus of the
esophageal motility disorder.
caudal RA. Although it causes no clinical signs, its presence
COR TRIATRIATUM may complicate surgical exposure of other structures at the
Cor triatriatum is an uncommon malformation caused by an left heart base. Portosystemic venous shunts are common
abnormal membrane that divides either the right (dexter) or and can lead to hepatic encephalopathy, as well as other
the left (sinister) atrium into two chambers. Cor triatriatum signs. These malformations are thought to be more prevalent
dexter occurs sporadically in dogs, often in combination in the Yorkshire Terrier, Pug, Miniature and Standard
with PS. Cor triatriatum sinister has been described rarely Schnauzers, Maltese, Pekingese, Shih Tzu, and Lhasa Apso
in cats; functional consequences are similar to mitral valve breeds and are discussed in Chapter 38.
stenosis.
Cor triatriatum dexter results from failure of the embry- Suggested Readings
onic right sinus venosus valve to regress. The caudal vena General References
cava and coronary sinus empty into the RA caudal to the Beijerink NJ, Oyama MA, Bonagura JD. Congenital heart disease.
intra-atrial membrane; the tricuspid orifice is within the In: Ettinger SJ, Feldman EC, Cote E, eds. Textbook of veterinary
cranial RA “chamber.” Obstruction to venous flow through internal medicine. 8th ed. St Louis: Elsevier; 2017:1207–1248.
the opening in the abnormal membrane elevates vascular Buchanan JW. Prevalence of cardiovascular disorders. In: Fox PR,
pressure in the caudal vena cava and the structures that drain Sisson D, Moise NS, eds. Textbook of canine and feline cardiology.
into it. 2nd ed. Philadelphia: Saunders; 1999:457.
Large- to medium-size breeds of dog are most often Oliveira P, et al. Retrospective review of congenital heart disease in
affected. Persistent ascites that develops at an early age is the 976 dogs. J Vet Intern Med. 2011;25:477–483.
most prominent clinical sign. Exercise intolerance, lethargy, Schrope DP. Prevalence of congenital heart disease in 76,301 mixed
breed dogs and 57,025 mixed-breed cats. J Vet Cardiol. 2015;17:
distended cutaneous abdominal veins, and sometimes diar- 192–202.
rhea are reported as well. Neither a cardiac murmur nor Tidholm A, et al. Congenital heart defects in cats: a retrospective
jugular venous distention is a feature of this anomaly. study of 162 cats (1996-2013). J Vet Cardiol. 2015;17(suppl
Thoracic radiographs indicate caudal vena cava distention 1):S215–S219.
without generalized cardiomegaly. The diaphragm may be Ventricular Outflow Obstruction
displaced cranially by massive ascites. The ECG usually is Buchanan JW. Pathogenesis of single right coronary artery and
normal. Echocardiography reveals the abnormal membrane pulmonic stenosis in English bulldogs. J Vet Intern Med. 2001;15:
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Doppler studies show the flow disturbance within the RA Bussadori C, et al. Balloon valvuloplasty in 30 dogs with pulmonic
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sure gradient. and 1-year outcome. J Vet Intern Med. 2001;15:553–558.
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orifice or excising the abnormal membrane to remove flow ratio for valvuloplasty in the treatment of pulmonic stenosis in
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using inflow occlusion, with or without hypothermia, can be did not undergo balloon valvuloplasty or surgery. J Small Anim
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ENDOCARDIAL FIBROELASTOSIS Kleman ME, et al. How to perform combined cutting balloon and
Diffuse fibroelastic thickening of the LV and LA endocar- high-pressure balloon valvuloplasty for dogs with subaortic ste-
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