Introduction

• Usually concurrent left-sided degenerative valve disease, rarely tricuspid degenerative valve disease with right-sided heart failure predominates over left-sided lesion. Can also be seen with degeneration of the aortic and/or pulmonic valves. 
• Insufficiency can be exacerbated by concurrent pulmonary hypertension. 
• Cause: insufficient right atrioventricular valve due to degenerative changes of the valve and associated structures.
• Signs: right-sided heart failure, murmur auscultated over the right apex can sometimes be appreciated.
• Diagnosis: signs, echocardiography.
• Treatment: symptomatic.

Pathogenesis

Etiology

• Degenerative process of collagen and glycosaminoglycans in valve leaflets. Mitral valve is usually more severely affected. See Heart: mitral valve degenerative disease for more information.

Predisposing factors

General

• Small breed dogs. 
• Middle-older age. 
• Degenerative mitral valve disease Heart: mitral valve degenerative disease.

Specific

• Development of pulmonary hypertension Cor pulmonale Pulmonary arterial hypertension (PHT) - may be due to concurrent chronic airway disease or secondary to chronic left-sided congestive failure.

• Raised right ventricular pressure due to concurrent congenital heart disease, eg pulmonic stenosis Pulmonic stenosis.
• Concurrent congenital tricuspid dysplasia Heart: tricuspid valve dysplasia.

Pathophysiology

• Myxomatous degeneration of tricuspid valve is almost always less severe than mitral valve.
• Valvular incompetence resulting in tricuspid regurgitation → volume overloading of right atrium and right ventricle, consequently right atrial and right ventricular enlargement.
• Development of right-sided heart failure is associated with raised end-diastolic right ventricular pressure and right atrial pressure → raised right atrial pressure causes backwards failure with increased systemic pressures.
• Hepatic venous drainage is compromised leading to hepatomegaly and hepatocellular damage → leaky hepatic sinusoids and raised, central venous pressure causes ascites.
• See also congestive heart failure Heart: congestive heart failure.

• Degenerative tricuspid valve disease → tricuspid regurgitation → right-sided volume overload → slow development of right atrial and right ventricular enlargement → right ventricular eccentric hypertrophy → further tricuspid incompetence.
• Increased right ventricular end-diastolic pressure and right atrial pressure → systemic venous congestion → increased central venous pressure → chronic hepatic venous congestion and hepatocellular cell damage (increased alanine transferase) → hepatic sinusoids are leaky → fluid extravasation into abdomen (ascites).
• Ascites and gastrointestinal edema may result in compromised absorption of nutrients (and drugs) and lead to signs like diarrhea.
• Pleural effusion may result from compromised pleural drainage into the systemic circulation.
• Hypoproteinemia Hypoproteinemia may result due to poor absorption, hepatic sinusoidal loss of protein, compromised liver function and inappetence.
• With severe long-standing right-sided congestive heart failure associated with ascites and hypoproteinemia, subcutanenous edema may occasionally be recognized due to altered capillary homeostasis (Starlings law).

Timecourse

• Development of right-sided heart failure is a poor prognostic sign and death (often euthanasia) usually follows within weeks or months.

Diagnosis

Treatment

Outcomes