Aortic Stenosis

CARDIOLOGY ()Map CARDIOVASCULAR CONDITIONS (Map)

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