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SAS - Subaortic Stenosis In A 9-Month-Old Male Mastiff Mixed Breed: Our Case Of the Month July 2022

Patient Information

Age
9 Months
Gender
Male, Intact
Species
Canine

Keywords

History

Clinical Signs

Exam Findings

Images

Normal left atrial size.
LV M-mode with normal FS (fractional shortening)
Pulmonary artery with color Doppler - normal valve structure, laminar flow and diameter
Subaortic stenosis. Note the narrowing at the aortic valve
Aortic velocity was excessive at 6.0 m/sec with secondary aortic insufficiency at 5.0 m/sec.

"Subaortic stenosis is one of the most common congenital heart defects in dogs, characterized by an obstruction of the left ventricular outflow tract, resulting in pressure overload on the left ventricle. It is  caused by fibrous nodules, a ridge or ring of fibrous or fibromuscular tissue located just below the aortic valve, which increases resistance to left ventricular outflow.   It most commonly occurs in  large breed dogs such as Newfoundlands, Boxers, Rottweilers, Golden Retrievers, Dogue de Bordeaux, German Shepherds, German Shorthaired Pointers, Great Danes, Bouvier des Flandres, and Mastiffs, and appears to be genetic in origin. Signs of subaortic stenosis can be present at birth or develop during the first year of life. Depending on the degree of resistance to left ventricular outflow and the resulting increase in outflow velocity, it can be graded as mild, moderate, severe and very severe (extreme)." - Peter Modler. See what a heart with subaortic stenosis looks like in a not-so-little 9-month-old male Mastiff mix puppy. Diagnostic imaging provided by Jenna Walsh, CVT of Animal Sounds Northwest, image interpretation by Eric Lindquist, DMV, DABVP, Cert. IVUSS, concise description of subarotic stenosis by Peter Modler, DVM, Dipl.-Tzt., Specialist German Board of Cardiology

 

 

 

History

A 9-month-old intact male Mastiff mixed breed with history of being underweight presented at a referral facility for echocardiogram due to heart murmur.

Image Interpretation

The echocardiogram in this patient demonstrated normal left atrial size based on 3 separate methods of LA evaluation. Mitral insufficiency noted at 6.3 m/sec. Concentric left ventricular hypertrophy noted in this patient with hypercontractility. The myocardium presented normal echogenicity without subjective evidence of significant fibrotic or ischemic disease. Aortic velocity was excessive at 6.0 m/sec with secondary aortic insufficiency at 5.0 m/sec. The right atrium and auricle revealed normal size, structure and content. No evidence of masses was noted. Tricuspid insufficiency noted at 2.8 m/sec. The right ventricle was of normal size (1/3 diameter of LV), chordae structure, myocardial echogenicity and thickness. Pulmonary outflow tract assessment revealed normal valve structure, laminar flow, and diameter (approx.1:1 pa/ao ratio). No visible pericardial or free pleura fluid was noted. The cranial mediastinum and pericardial and extra-cardiac regions were free of masses in the visible window. Periodic arrhythmia noted.

DX

Subaortic stenosis with concurrent mitral and tricuspid insufficiency - Secondary left ventricular hypertrophy. - Periodic arrhythmia.

Outcome

Atenolol therapy was recommended in this patient depending upon EKG results. Guarded to poor long-term prognosis. Blood pressure measurements were indicated if not already performed. Follow up with the patient's RDVM was unfortunately not available at the time of this study posting, we hope he is doing ok.

Videos

Concentric left ventricular hypertrophy noted in this patient with hypercontractility.
Subaortic stenosis. Note the narrowing at the aortic vale
Excessive aortic velocity.