Balloon valvuloplasty of valvular pulmonic stenosis in the dog

Balloon valvuloplasty has become the accepted method of therapy for the majority of dogs with valvular pulmonic stenosis. Success rate of balloon valvuloplasty is excellent but the procedure can have a steep learning curve. An understanding of the equipment used and specifics of the procedure is important to maximize success and minimize risk. This paper will review criteria for choosing candidates for balloon valvuloplasty, discuss the equipment used, discuss the procedure in detail, and finally discuss assessment of success and possible complications.     

Surgical correction of pulmonic stenosis using transventricular pulmonic dilation valvuloplasty (Brock) in a dog

A two-month-old male long coated Chihuahua, which had symptoms including anorexia and decreased growth, was diagnosed with pulmonic valvular stenosis. Echocardiography showed the severe progression of pulmonary arterial velocity (6.29 m/s, Pressure gradient (PG); 158 mmHg). Transventricular pulmonic dilation valvuloplasty (Brock) was conducted, and stenosed valve was dilated by the oto forceps. Pleural effusion was observed postoperatively, however, it was diminished under the intensive care for five days after the surgery. The right ventricular systolic pressure was decreased to 60 mmHg in angiocardiography conducted two months postoperatively and the dog has kept a good general condition with recovered vigor and appetite.     

Percutaneous balloon valvuloplasty in four dogs with pulmonic stenosis

Four young dogs with severe pulmonic stenosis were treated by percutaneous balloon valvuloplasty. Pressure gradients between the right ventricle and pulmonary artery were markedly reduced by the procedure resulting in dramatic improvements in growth rate and clinical condition. No postoperative problems were encountered.     

Increased chymase-like activity in a dog with congenital pulmonic stenosis

ObjectivesThis study was intended to compare the tissue chymase-like activity and angiotensin converting enzyme (ACE) activity in the right and left ventricles of a dog with congenital pulmonic stenosis (PS), with normal dogs, and to discuss the potential clinical implications of these findings.Animals, materials and methodsStudy subjects included a one-year-old Beagle dog with spontaneous PS and six clinically normal Beagles. Chymase-like and ACE activities were determined in all hearts by high pressure liquid chromatography.ResultsIn the PS dog right ventricular (RV) chymase-like activity (49.79 nmol/min/g tissue) and left ventricular (LV) chymase-like activity (36.85 nmol/min/g tissue) were elevated vs normal Beagle dogs (mean ± standard deviation, RV: 20.17 ± 5.24 nmol/min/g, LV: 19.03 ± 3.27 nmol/min/g).ConclusionsActivation of the tissue RAA system was detected in a dog with congenital PS. This interesting finding should be pursued with further studies to validate this result, and to explore whether pharmacological blockade of chymase, or the angiotensin II receptor, represents a useful strategy to prevent myocardial remodeling in this condition.     

Results of balloon valvuloplasty in 40 dogs with pulmonic stenosis

The records of 43 dogs presenting with severe pulmonic stenosis in which balloon valvuloplasty was attempted were reviewed. Thirty-four dogs (79 per cent) were symptomatic at initial presentation. All patients were selected for balloon valvuloplasty on the basis of a Doppler-derived trans-stenotic pressure gradient of over 80 mmHg and concurrent evidence of mild to severe right ventricular hypertrophy. Forty dogs underwent balloon valvuloplasty; the procedure was not performed in three dogs because of an aberrant coronary artery in two cases and because catheterisation of the pulmonary artery was not possible in the third. Overall, 37 out of the 40 dogs (93 per cent) were successfully ballooned, resulting in a mean reduction in the pressure gradient of 46 per cent, with a mean pressure gradient of 124 mmHg on presentation and 67 mmHg six months after the procedure. Three dogs died during balloon valvuloplasty (all of which had a concurrent defect) and three dogs showed a poor clinical response to the procedure. Thus balloon valvuloplasty was successful and resulted in a sustained clinical improvement in 80 per cent of previously symptomatic cases. This study was undertaken to document the results of balloon valvuloplasty in a larger population of dogs than has previously been published.     

Stent angioplasty for treatment of canine valvular pulmonic stenosis

Four dogs presented for evaluation and treatment of severe pulmonic valve stenosis and underwent stenting of the pulmonic valve annulus using bare-metal balloon-expandable stents. All dogs survived the procedure with immediate reduction of the transpulmonary valve pressure gradient and increase in activity levels. One dog had a stent fracture and migration 1 month after the intervention. This dog underwent a second procedure, in which multiple stents were used to alleviate the obstruction. The stents that were placed at the level of the right ventricular outflow tract fractured within 1 month of the procedure, and the patient died when a third (surgical) approach was attempted. The other three dogs remain alive 54, 42, and 29 months after the procedure. Stent angioplasty may be a viable option for dogs with valvular pulmonic stenosis in which routine balloon valvuloplasty does not provide a successful outcome. Aggressive attempts to diminish RVOT dynamic obstruction with high-dose beta blockade and avoiding deployment of the stent within the RVOT are recommended to prevent stent fracture and migration.     

Transcatheter intravascular stent placement to relieve supravalvular pulmonic stenosis

Valvular pulmonic stenosis has been successfully treated in dogs via minimally invasive transcatheter balloon dilation procedures for almost 20 years. Supravalvular pulmonic stenosis however is not amenable to balloon dilation procedures. Although several surgical procedures are described for treatment of pulmonic stenosis, the morbidity and mortality of these procedures are significantly higher than for transcatheter approaches.Two cases of supravalvular pulmonic stenosis are presented, one acquired and one congenital, which were successfully treated with transcatheter intravascular stent placement. The procedure alleviated the stenotic lesion and resolved clinical signs.     

Percutaneous balloon valvuloplasty for treatment of pulmonic stenosis in a dog

A 2.5-year-old dog with congenital pulmonary valve dysplasia was treated by percutaneous balloon dilation of the stenotic orifice. Clinical and hemodynamic improvement was apparent immediately and for 9 months after the valvuloplasty procedure.     

Pathogenesis of single right coronary artery and pulmonic stenosis in English Bulldogs

English Bulldogs are the most common breed to have pulmonic stenosis. Previous studies showed that this congenital heart abnormality in Bulldogs frequently is caused by a circumpulmonary left coronary artery originating from a single right coronary artery. Fetal anasarca also occurs often in Bulldogs and might represent congestive heart failure, but the cause is unknown. To determine if fetal anasarca is associated with a coronary anomaly and pulmonic stenosis, major coronary arteries were studied in 6 bulldog puppies with fetal anasarca. Five of the puppies had normal coronary arteries, and this led to the conclusion that fetal anasarca usually is not associated with major coronary abnormalities or pulmonic stenosis. The 6th puppy had single right coronary artery with circumpulmonary left coronary artery and moderate subvalvular pulmonic stenosis. Serial section histology suggests that the underlying cause of this syndrome is malformation of the left aortic sinus (of Valsalva) and inversion of the proximal segment of the left main coronary artery.     

Pulmonary artery dissection following balloon valvuloplasty in a dog with pulmonic stenosis

A 3-month-old, 9.9 kg, male pit bull cross was referred for evaluation of collapse. A left basilar systolic heart murmur graded V/VI and a grade IV/VI right basilar systolic heart murmur were ausculted. Echocardiography showed severe pulmonic stenosis characterized by annular hypoplasia, leaflet thickening, and leaflet fusion. After 1 month of atenolol therapy, a pulmonic valve balloon valvuloplasty procedure was performed, and the intra-operative right ventricular pressure was reduced by 43%. Echocardiography, performed the following day, showed apparent rupture of a pulmonary valve leaflet and a membranous structure within the pulmonary artery consistent with a dissecting membrane. Short-term follow-up has shown no apparent progression of the pulmonary artery dissection and the patient remains free of clinical signs.     

Surgical treatment of severe pulmonic stenosis under cardiopulmonary bypass in small dogs

Objectives : The aim of this study was to report the long‐term outcome of the surgical palliation of pulmonic stenosis in dogs. Methods : The subjects comprised three female and six male dogs, mean (±sd) age: 23 (±25) months, mean (±sd) weight: 3·4 (±2·1) kg, diagnosed with severe pulmonic stenosis and right ventricular hypertrophy, with an average preoperative pressure gradient of 153 (±43) mmHg on echocardiography. Results : The pressure overload with severe pulmonic stenosis was reduced by valvotomy, i.e., open pulmonary valve commissurotomy, with/without biomembrane patch grafting, under cardiopulmonary bypass. The postoperative pressure gradient at 1 to 7 days was significantly decreased to 65 (±39) mmHg (P<0·05). The reduced pressure gradient was maintained at 58 (±38) mmHg at final follow‐up. Clinical Significance : Open valvotomy, pulmonary valve commissurotomy and biomembrane patch grafting were effective in reducing obstruction in severe pulmonic stenosis in dogs.     

Percutaneous catheter-based treatment of pulmonic stenosis and patent ductus arteriosus in a dog

A 6-months old female German shepherd dog was referred for management of congenital heart disease. A diagnosis of pulmonic stenosis (PS) and patent ductus arteriosus (PDA) was confirmed by Doppler echocardiography and cardiac catheterisation. The conditions were treated during a single cardiac catheterisation procedure using percutaneous techniques. Gianturco coil embolisation was used to close the PDA, and the PS was relieved using a balloon valvuloplasty technique.