Brief CommunicationTranscatheter intravascular stent placement to relieve supravalvular pulmonic stenosis☆
Introduction
Congenital heart disease has been reported to occur in 0.46 to 0.85% of dogs, with pulmonic stenosis accounting for 11–23% of these patients.1, 2, 3 Acquired pulmonic stenosis, although rare, has also been reported to occur due to mass lesions obstructing the right ventricular outflow tract.4 Congenital pulmonic stenosis is over represented in several breeds including the English Bulldog, Scottish Terrier, Wirehaired Fox Terrier, Miniature Schnauzer, West Highland White Terrier, Chihuahua, Jack Russell Terrier, Boxer, Beagle, Mastiff and Samoyed.1, 2, 5 Inheritance has been demonstrated in several breeds, with a polygenic mode of transmission.6
Pulmonic stenosis has been classified as either subvalvular, valvular or supravalvular.1, 7 Valvular pulmonic stenosis is most common and can be due to either commissural fusion or dysplasia of the valve cusps, with or without hypoplasia of the valve annulus.7, 8, 9 Primary supravalvular and subvalvular lesions are less common. Infundibular hypertrophy, although reported as a primary lesion, is most commonly secondary to right ventricular hypertrophy which develops in response to the pressure overload imposed by a primary subvalvular, valvular or supravalvular lesion.7 Several systems for estimating the severity of pulmonic stenosis have been reported; most reports define severe pulmonic stenosis as a Doppler derived pressure gradient greater than 80 mmHg.c,10, 11 Relief of severe pulmonic stenosis, with balloon dilation, has been shown to relieve clinical signs and increase survival in dogs.c11
Balloon dilation to relieve valvular stenosis due to commissural fusion has been widely reported in the veterinary literature.d,12, 13, 14, 15, 16 To date commissural fusion is the only lesion which has been shown to consistently respond to balloon dilation in veterinary patients. In those patients in which balloon dilation is not appropriate, a number of palliative surgical procedures have been reported.10, 17, 18, 19 However, regardless of procedure, the morbidity and mortality associated with surgery is significantly greater than that of catheter based procedures.10, 17, 18, 19
Transcatheter intravascular stent placement has been reported for the correction of both acquired and congenital supravalvular pulmonic stenosis in humans.20, 21 This report describes the successful use of transcatheter intravascular stent placement for relief of supravalvular pulmonic stenosis in two dogs.
Section snippets
Methods
All echocardiograms were obtained with a Vivid 5 echocardiographic recorder.e Two-dimensional, M-mode and Doppler measurements were performed with 10/4.4 and 3.6/1.5 MHz phased array sector transducers. Echocardiographic measurements were made according to accepted previously reported standards.22, 23 M-mode measurements were performed in triplicate and averaged.
Six-lead ECG was recorded using an EKG unit
Case history 1
An 11 month-old male intact Cocker Spaniel (11.2 kg) was referred to Colorado State University Veterinary School with an incidental murmur noted by the referring veterinarian. The dog was asymptomatic according to the owner.
On auscultation, a grade V/VI holosystolic left basilar murmur was evident, with a palpable thrill over the left cranial thorax. All other cardiovascular findings were within normal limits on physical examination.
Echocardiography showed severe right ventricular hypertrophy, a
Discussion
Since the first report of its use,25 balloon dilation has rapidly become the standard of care in veterinary practice for treatment of valvular pulmonic stenosis.d,12, 13, 14, 15, 16 Application of balloon dilation is limited to valvular pulmonic stenosis where commissural fusion is the major abnormality. Many surgical options exist for treatment of pulmonic stenosis;10, 17, 18, 19 however due to the increased morbidity and mortality of these procedures they are often reserved for those animals
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Cited by (19)
Transmembrane stent placement for cor triatriatum dexter in 6 dogs
2022, Journal of Veterinary CardiologyTransvalvular pulmonic stent angioplasty: procedural outcomes and complications in 15 dogs with pulmonic stenosis
2021, Journal of Veterinary CardiologyCitation Excerpt :In addition, balloon dilation of significant supravalvular stenosis has been associated with an increased risk of PA dissection caused by an intimal tear or vessel wall rupture [11,12], but has been successfully performed by some centers. Alternatives to balloon valvuloplasty have been considered, including an open patch-graft technique [13–16], surgical implantation of a conduit around the stenotic lesion [8,17], and transvascular stent angioplasty [11,18,19]. A stent bio-valve has been reported in experimental canine models [20].
A novel hybrid stent technique to treat canine pulmonic stenosis
2020, Journal of Veterinary CardiologyTreatment of caudal cavoatrial junction obstruction in a dog with a balloon-expandable biliary stent
2019, Journal of Veterinary CardiologyStent placement for palliation of cor triatriatum dexter in a dog with suspected patent foramen ovale
2016, Journal of Veterinary CardiologyCitation Excerpt :Such an issue could have easily prevented the proper placement of the stent across the membrane. Griffiths et al. reported the use of a balloon-in-balloon catheter to deliver an intravascular stent within the pulmonary artery in two dogs.21 In these cases, the inner balloon was dilated initially to engage the stent, preventing dislocation and aiding in correct “dog bone” inflation of the outer balloon.
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