R L Winter 1, K L Maneval 2, C S Ferrel 2
Background:
Pulmonary valvar stenosis (PVS) is a common congenital heart defect in dogs, but concurrent mid-right ventricular obstructions such as infundibular stenosis (IS) are rare. When both are present, they create serial obstructions to right ventricular outflow, compounding pressure overload. Balloon valvuloplasty is standard for PVS, but its application to combined PVS and IS has not been well-documented. This report describes the diagnosis and interventional management of concurrent PVS and IS in a dog.
Methods:
A two-year-old female Cocker Spaniel, previously diagnosed with PVS and treated with balloon valvuloplasty at eight months of age, was referred for progressive obstruction. Echocardiography revealed severe right ventricular hypertrophy, right atrial dilation, and a discrete fibromuscular lesion at the crista supraventricularis consistent with IS, located 11 mm from the pulmonary annulus. Pulmonary valve leaflets showed systolic doming. Peak systolic pressure gradient across the pulmonary annulus was 190 mmHg. Intervention involved percutaneous jugular access, selective angiography, and sequential dilation using an 8 mm cutting balloon at the mid-RV obstruction followed by an 18 mm high-pressure balloon across both obstructions.
Results:
Immediately post-procedure, the pressure gradient fell from 190 mmHg to 65 mmHg, with improved leaflet mobility and reduced chamber dilation. At three months, the gradient was 51 mmHg, and at nine months it had further decreased to 30 mmHg. The dog remained clinically stable with continued atenolol therapy.
Limitations:
As a single case, the findings cannot be generalized. Long-term durability of the intervention remains unknown, and invasive pressure measurements were not obtained. The exact histologic nature of the mid-RV lesion could not be confirmed.
Conclusions:
This is the first reported canine case of concurrent PVS and IS successfully treated with combined cutting and high-pressure balloon angioplasty. The favorable hemodynamic improvement suggests this technique can be effective for complex, serial right ventricular outflow tract obstructions. Progressive postnatal development of IS following early-life PVS diagnosis is possible and should be considered in cases with worsening gradients despite prior intervention.
Transthoracic, right parasternal short-axis echocardiographic image demonstrating systolic doming of the pulmonary leaflets (white arrow) and a hyperechoic, obstructive, mid-right ventricular membrane using simultaneous two-dimensional and color Doppler imaging. RA: right atrium; RV: right ventricle; RVOT: right ventricular outflow tract.
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