Felis ISSN 2398-2950

Heart: tricuspid valve dysplasia

Synonym(s): Atrioventricular valve dysplasia; TVD

Contributor(s): Josephine Dandrieux, Mark Oyama, Mark Rishniw, Liz Bode

Introduction

  • TVD is a congenital defect of the tricuspid valve and its related structures (ie papillary muscles and chordae tendineae).
  • It is uncommon, representing approximately 5% of congenital heart disease in cats.
  • TVD causes tricuspid regurgitation, right heart enlargement, and in severe cases, right heart failure. 
  • In older cats, arrhythmogenic right ventricular cardiomyopathy is often misdiagnosed as tricuspid valve dysplasia.
  • Signs: depends on severity. In some an symptomatic heart murmur is identified and animals can remain subclinical for years. In more severe cases the cat can develop congestive heart failure and common clinical signs include abdominal distension, jugular pulses, weakness, and poor appetite. 
  • Treatment: involves standard medical therapy for heart failure. 
  • Prognosis: poor in severely affected animals.

Pathogenesis

Etiology

  • TVD causes varying degrees of tricuspid regurgitation, right heart volume overload and enlargement, and right-sided congestive heart failure.
  • TVD includes a spectrum of anatomical lesions including focal or diffuse thickening or shortening of the valve leaflets, focal agenesis of the valve, shortened chordae tendineae, incomplete separation of the valve leaflets from the ventricular or septal wall, malpositioned and underdeveloped of the papillary muscles, fenestrations of the valve leaflets, and varying degrees of concurrent valve stenosis. 
  • Ebstein's anomaly may be identified, where the basal attachment of the tricuspid valve is displaced apically.

Pathophysiology

  • TVD causes tricuspid regurgitation and progressive right-sided eccentric hypertrophy. As the right ventricle and atrium enlarge, the annulus of the tricuspid valve orifice increases, and due to the inability of the defective valves to cover this increasing area, the degree of regurgitation worsens.  Inasmuch as this cycle perpetuates itself, the degree of volume overload continues to increase. As the amount of regurgitation increases, forward right ventricular stroke volume can fall and lead to decreased venous return into the left heart. Activation of the renin-angiotensin-aldosterone (RAAS) system leads to right-sided heart failure, usually manifest as ascites, and occasionally pleural effusion Pleural effusion or chylothorax Chylothorax.
  • Supraventricular arrhythmias may result from right atrial stretch.
  • Thromboembolic sequelae may also be seen as thrombi develop in right atrium and embolize to lungs.

Timecourse

  • Many cats with severe TVD can remain subclinical well into adulthood.  Only after a protracted period of progressive heart enlargement do animals present with clinical signs. By this time, their hearts are often extremely enlarged. 
  • Many cats that finally present with clinical signs are in the end-stages of their disease, and therefore prognosis is guarded.
  • Therapy can be maintained for several years, although quality of life may be compromised.

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Schrope D P (2015) Prevalence of congenital heart disease in 76, 301 mixed-breed dogs and 57, 025 mixed-breed cats. J Vet Cardiol 17 (3), 192-202 PubMed.
  • Riesen S C, Kovacevic A, Lombard C W et al (2007) Echocardiographic screening of purebred cats: an overview from 2002 to 2005. Schweiz Arch Tierheilkd 149 (2), 73-76 PubMed.
  • Harvey A M, Battersby I A, Faena M et al (2005) Arrhythmogenic right ventricular cardiomyopathy in two cats. JSAP 46 (3), 151-156 PubMed.
  • Chetboul V, Tran D, Carlos C et al (2004) [Congenital malformations of the tricuspid valve in domestic carnivores: a retrospective study of 50 cases]. Schweiz Arch Tierheilkd 146 (6), 265-275 PubMed.
  • Fox P R, Maron B J, Basso C et al (2000) Spontaneously occurring arrhythmogenic right ventricular cardiomyopathy in the domestic cat: a new animal model similar to the human disease. Circulation 102 (15), 1863-1870 PubMed.
  • Kornreich B G, Moïse N S (1997) Right atrioventricular valve malformation in dogs and cats: an electrocardiographic survey with emphasis on splintered QRS complexes. J Vet Intern Med 11 (4), 226-30 PubMed.
  • Fossum T W, Miller M W, Rogers K S et al (1994) Chylothorax associated with right-sided heart failure in five cats. JAVMA 204 (1), 84-89 PubMed.
  • Liu S K, Tilley L P (1976) Dysplasia of the tricuspid valve in the dog and cat. JAVMA 169 (6), 623-30 PubMed.

Other sources of information

  • Cote E, MacDonald K A, Meurs K M, Sleeper M (2011) Feline Cardiology. 1st edn. Wiley-Blackwell, UK.
  • Fox P R, Sisson D D, Moise N S (eds) (1999) Textbook of Canine and Feline Cardiology. 2nd edn. WB Saunders, Philadelphia.
  • Kittleson M D, Kienle R D (1998) Small Animal Cardiovascular Medicine. Mosby, St. Louis.


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