Aortic Stenosis

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CARDIOLOGY
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  • Common in dogs: especially subvalvular lesions; Boxers usually have valvular stenosis
  • Rare in cats: usually they get supravalvular lesions


Signalment

Genetics & Predisposed Breeds: Newfoundland, Boxer, German Shepherd, Golden Retriever, Bull Terrier


Description

The three possible areas for aortic stenosis to occur:

1. Subvalvular or subaortic (occurs below the valve)

2. Valvular or aortic (occurs at the valve)

3. Supravalvular (occurs after the valve)


  • The stenotic area is a consequence of fibrous tissue on and around the aortic valve
  • A narrowing of the aortic outflow tract causes an increase in pressure
  • Increased pressure leads to left ventricular dilation and concentric hypertrophy as a means of maintaining sufficient cardiac output
  • The severity of stenosis determines the extent of hypertrophy
  • Hypertrophy of the myocardium leads to an increased oxygen demand and decreased diastolic filling
  • Insufficient oxygen to meet the new needs of the hypertrophied left ventricle predisposes the animal to ventricular arrhythmias
  • There is an increased risk of bacterial endocarditis in animals affected by this condition

Diagnosis

History & Clinical Signs

-Weakness

-Exercise Intolerance

-Syncope

-Stunting of Growth

-Pallor

-Or may be asymptomatic


Physical Exam

-Systolic murmur (Loudest over aortic valve)

-Weak femoral pulses


Radiographic Findings

-Left ventricular enlargement or bulge around the aortic valve

-Radiographs may appear normal due to concentric hypertrophy


Electrocardiography (ECG)

-Increased R-wave amplitude (Indicates Left Ventricular Hypertrophy)

-Ventricular Arrhythmias (Only Severely Affected Animals)


Echocardiography

-Left ventricular concentric hypertrophy

-Fibrous Tissue around aortic valve

-Dilation ascending aorta

-Dilation of the left atrium


Treatment

Palliative Treatment=alleviate symptoms without curing disease

-Exercise Restriction

-B-Blockers (Prevent/Control Ventricular Arrhythmias)

Surgical Treatment=currently poor outcome

-Balloon Valvuloplasty


Prognosis

Mild to Moderate SAS:

-Normal quality of life if there is no progression of the malformation

Severe SAS:

-Poor quality of life

-Complications from development of congestive heart failure or cardiac arrhythmias

-Sudden death within the first 1-3 years of life