Echoguided closed commissurotomy for mitral valve stenosis in a dog

Surgical treatment of mitral stenosis (MS) usually consists of open mitral commissurotomy (MC) or percutaneous balloon MC, which require a cardiopulmonary bypass or transseptal approach, respectively. We describe here the first surgical management of congenital MS in a dog using a less invasive procedure, a surgical closed MC under direct echo guidance. A 5-year-old female Cairn terrier was referred for ascites, weakness, and marked exercise intolerance for 2 months, which was refractory to medical treatment. Diagnosis of severe MS associated with atrial fibrillation (AF) was confirmed by echo-Doppler examination and electrocardiography. Poor response to medical treatment suggested a corrective procedure on the valve was indicated. However, due to the cost and high mortality rate associated with cardiopulmonary bypass, a hybrid MC was recommended. A standard left intercostal thoracotomy was performed and three balloon valvuloplasty catheters of differing diameters were sequentially inserted through the left atrium under direct echo guidance. Transesophageal echocardiography revealed a 62% reduction in the pressure half-time compared to the pre-procedure. Thirteen months after surgery the dog is still doing well with resolution of ascites and a marked improvement of most echo-Doppler variables.     

Balloon valvuloplasty of congenital mitral stenosis

Radiographic, echocardiographic, fluoroscopic, and angiographic images from 2 dogs with severe congenital mitral valve stenosis that underwent cardiac catheterization and balloon valvuloplasty are presented. Both dogs displayed systolic doming of the mitral valve leaflets, increased diastolic pressure gradient across the left atrium and ventricle, and decreased mitral inflow E to F slope. Balloon valvuloplasty was performed on both dogs using atrial transeptal puncture.     

Mitral Stenosis in 15 Dogs

Mitral stenosis was diagnosed in 15 young to middle-aged dogs. There were 5 Newfoundlands and 4 bull terriers affected, suggesting a breed predisposition for this disorder. Clinical signs included cough, dyspnea, exercise intolerance, and syncope. Soft left apical diastolic murmurs were heard only in 4 dogs, whereas 8 dogs had systolic murmurs characteristic of mitral regurgitation. Left atrial enlargement was the most prominent radiographic feature. Left-sided congestive heart failure was detected by radiographs in 11 dogs within 1 year of diagnosis. Electrocardiographic abnormalities varied among dogs and included atrial and ventricular enlargement, as well as atrial and ventricular arrhythmias. Abnormalities on M-mode and two-dimensional echocardiograms included abnormal diastolic motion of the mitral valve characterized by decreased leaflet separation, valve doming, concordant motion of the parietal mitral valve leaflet, and a decreased E-to-F slope. Increased mitral valve inflow velocities and prolonged pressure half-times were detected by Doppler echocardiography. Cardiac catheterization, performed in 8 dogs, documented a diastolic pressure gradient between the left atrial, pulmonary capillary wedge, or pulmonary artery diastolic pressures and the left ventricular diastolic pressure. Necropsy showed mitral stenosis caused by thickened, fused mitral valve leaflets in 5 dogs and a supramitral ring in another dog. The outcome in affected dogs was poor; 9 of 15 dogs were euthanatized or died by 2 1/2 years of age.     

Pulmonary artery dissection following pulmonary balloon valvuloplasty in dogs

Introduction/objectivesPulmonary artery dissection is a rare complication following balloon valvuloplasty for pulmonic stenosis. We sought to report the rate of this complication in dogs and describe the demographic, clinical, procedural, and outcome data in affected dogs.Animals, materials and methodsMedical records at a single academic institution between 2002 and 2021 were reviewed for dogs with pulmonic stenosis treated by a balloon valvuloplasty. Dogs were included for evaluation if there was evidence of pulmonary artery dissection on echocardiography or necropsy following balloon valvuloplasty. The demographic, clinical, surgical, and follow-up information were then recorded.ResultsSix dogs were included from 210 balloon valvuloplasty procedures for pulmonic stenosis giving a 3.9% rate of pulmonary dissection. There was a variety of signalment, pulmonary valve morphologies, and balloon catheter types used in each dog. All dogs had severe pulmonic stenosis (median pressure gradient of 208 mmHg, range 94–220 mmHg) with 5/6 dogs having a pressure gradient >144 mmHg. The median balloon to pulmonary valve annulus ratio was 1.35 (range 1.25–1.5). Three dogs died perioperatively, and three dogs were alive at follow up 3.3, 4.0, and 4.1 years postoperatively.ConclusionPulmonary artery dissection is a rare complication following balloon valvuloplasty for pulmonic stenosis. Extreme elevations in preoperative pulmonary valve flow velocity were common. Prognosis is variable, with a potential 50% perioperative survival rate, but extended survival times were noted in those patients discharged from hospital.     

Balloon dilatation of nasopharyngeal stenosis in a dog

CASE DESCRIPTION: A dog was examined because of a 6-month history of upper airway stridor that began after postoperative regurgitation of gastric contents. CLINICAL FINDINGS: Constant stridor was evident during inspiration and expiration, although it was worse during inspiration. The stridor was no longer evident when the dog's mouth was manually held open. Computed tomography, rhinoscopy, and fluoroscopy were used to confirm a diagnosis of nasopharyngeal stenosis. TREATMENT AND OUTCOME: The dog was anesthetized, and balloon dilatation of the stenosis was performed. Prednisone was prescribed for 4 weeks after the procedure to decrease fibrous tissue formation. Although the dog was initially improved, signs recurred 3.5 weeks later, and balloon dilatation was repeated. This time, however, triamcinolone was injected into the area of stenosis at the end of the dilatation procedure. Two months later, although the dog did not have clinical signs of stridor, a third dilatation procedure was performed because mild stenosis was seen on follow-up computed tomographic images; again, triamcinolone was injected into the area of stenosis at the end of the dilatation procedure. Three and 6 months after the third dilatation procedure, the dog reportedly was clinically normal. CLINICAL RELEVANCE: Findings suggest that balloon dilatation may be an effective treatment for nasopharyngeal stenosis in dogs.     

Treatment of Congenital Pulmonic Stenosis in Two Dogs by Balloon Valvuloplasty

Balloon valvuloplasty was performed on two dogs with pulmonic valve stenosis. Immediately following balloon valvuloplasty, peak right ventricular systolic pressure declined from 92 to 44 mm Hg in the first dog and from 108 to 46 mm Hg in the second dog. The peak systolic pressure gradient across the pulmonic valve declined from 60 to 12 mm Hg in the first dog and from 84 to 22 mm Hg in the second dog. Hemodynamic improvement was sustained in both dogs at the time of recatheterization 3 months later. Both dogs tolerated the procedure well and there were no serious complications. It was concluded that balloon valvuloplasty offers an alternative to surgery for the treatment of valvular pulmonic stenosis in dogs. The exact indications for and limitations of balloon valvuloplasty must await the results of additional and more long-term studies.     

Transthoracic echocardiographically-guided interventional cardiac procedures in the dog

ObjectivesInterventional cardiac procedures are traditionally performed using fluoroscopy, or, more recently, transesophageal echocardiography (TEE). Neither modality is widely available to practicing cardiologists worldwide. We examined whether balloon valvuloplasty of pulmonic stenosis (PS) and transarterial occlusion of patent ductus arteriosus (PDA) in dogs could be performed safely with transthoracic echocardiography (TTE).AnimalsA prospective consecutive case series of 26 client-owned dogs with PS (n = 10) and PDA (n = 16).MethodsThe cardiovascular procedures were performed using TTE. Each dog was positioned on a standard echocardiography table in right lateral recumbency (dogs with PS) or left lateral recumbency (dogs with PDA). Guide wires, balloon catheters, Amplatz^® Canine Ductal Occluder (ACDO) delivery sheaths, and ACDO were imaged by standard echocardiographic views optimized to allow visualization of the defects and devices.ResultsProcedures were performed successfully without major complications in 20 dogs. In 2 dogs (German shepherds) with Type III PDA, ACDO placement was unsuccessful; 2 other German Shepherds were excluded from the procedure because their ductal diameters, measured echocardiographically, exceeded the limits of the maximal ACDO size. Two dogs weighing ≤3.5 kg had suboptimal echocardiographic visualization of the PDA and were considered too small for safe ACDO deployment. All intravascular devices at the level of the heart and great vessels appeared hyperechoic on TTE image and could be clearly monitored and guided in real-time.ConclusionsWe have demonstrated that TTE monitoring can guide each step of pulmonic balloon valvuloplasty and PDA occlusion without fluoroscopy.     

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.     

Assessment of balloon pulmonary valvuloplasty in six dogs

The effectiveness of balloon valvuloplasty was assessed, clinically and haemodynamically, in six dogs with moderate to severe pulmonic stenosis. The haemodynamic assessment was based on Doppler echocardiography, with colour flow mapping, in the conscious dog and by direct catheterisation in the anaesthetised dog, before and after balloon valve dilatation. Four of the six dogs were presented with exercise intolerance, of which two were in congestive heart failure. Balloon valvuloplasty resulted in improved exercise tolerance and resolution of congestive heart failure in these dogs. The average Doppler and catheter transvalvular pressure gradients were reduced to 43 per cent and 46 per cent of the preoperative gradient, respectively. The average pressure gradient obtained by catheter, in the anaesthetised dog, was 59 per cent of the pressure gradient obtained by spectral Doppler echocardiography in the conscious dog. Balloon valvuloplasty was considered successful in five out of the six dogs. Postoperative pulmonic regurgitation was not found to be a complication of balloon valvuloplasty.     

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.     

Balloon valvuloplasty in 30 dogs with pulmonic stenosis: effect of valve morphology and annular size on initial and 1-year outcome

Case records of 30 dogs in which valvular pulmonic stenosis (PS) was treated by balloon dilation were reviewed retrospectively. Physical examination, thoracic radiographs, 9-lead ECG, echocardiography, and Doppler studies were performed in all dogs. Two-dimensional and Doppler echocardiography were repeated after 24 h and 1 year after treatment. Dogs were divided into 2 groups based on their valvular anatomy on echocardiography and aortic:pulmonary ratio: 18 had type A PS with normal annulus diameter and aortic:pulmonary ratio < or = 1.2, and 12 had type B PS with pulmonary annulus hypoplasia and aortic:pulmonary ratio > 1.2. Most dogs in the type B group were brachycephalic and had no poststenotic dilatation on thoracic radiographs. Of the dogs with type A stenosis, 100% survived valvuloplasty with resolution of clinical signs. At 1-year follow-up, 94.4% were still alive and remained asymptomatic. Of those with type B stenosis, 66.6% had favorable outcome postvalvuloplasty. At 1-year follow-up, 66.6% of dogs were alive, and resolution of clinical signs was obtained in 50%. This study revealed the immediate and long-term efficacy of balloon valvuloplasty in dogs with PS.     

Balloon Valvuloplasty for Treatment of Pulmonic Stenosis in English Bulldogs with an Aberrant Coronary Artery

Background: English Bulldogs (EB) with pulmonic stenosis (PS) sometimes have an aberrant coronary artery (CA) type R2A encircling the pulmonary artery (PA). Balloon valvuloplasty (BV) is treatment of choice for severe PS, but is considered to be contraindicated in dogs with aberrant CA. Hypothesis: Conservative BV in EB with aberrant CA is safe and improves clinical signs and quality of life. Animals: Four client‐owned EB with severe PS were retrospectively reviewed/analysed. Methods: Retrospective study: Case records, echocardiography, BV, and follow‐up investigations of EB diagnosed with severe PS and treated with BV were reviewed. The ratios of PA to aortic (Ao) velocity time integral (VTI) were calculated to assess progression/improvement of PS. Results: An aberrant CA was confirmed on angiography in all EB. Conservative BV was performed, using a balloon of the size of the PA annulus or smaller (0.6–1 × PA annulus size). All dogs survived the procedure, but only a mild reduction in pressure gradient was achieved. There was an improvement in PA to Ao VTI in 3 of 4 dogs (P≤ .017), which were free of evidence of congestive heart failure (CHF) 5, 10, and 15 months after BV. One dog that had right‐sided CHF when BV was performed died due to progressive right‐sided CHF within 3 months. Conclusions: Conservative BV in EB might be safe and might improve quality and quantity of life.     

Left ventricular outflow tract obstruction caused by a congenital accessory mitral valve leaflet and treated by open-heart surgery in a young dog

A 3-month-old Shetland sheepdog presented with a loud ejection murmur and exercise intolerance. Echocardiography revealed an accessory mitral valve leaflet, characterised by a valve-like structure separate from the mitral valve seen in the subaortic region of the ventricular septum. The left ventricular outflow tract was partially obstructed with a pressure gradient of 12 mmHg. Accessory mitral valve leaflet resection and mitral valvuloplasty were performed during open-heart surgery. Histology performed on the membrane-like structures were indicative of fibrous connective tissues. Postoperative echocardiography confirmed removal of the valve-like structure with resolution of the left ventricular outflow tract obstruction. The pressure gradient was decreased to 4.6 mmHg. The dog was in good condition and no further treatment was required 5 months after surgery. Both cardiac troponin I and NT-proBNP were markedly decreased. In this dog, surgical resection combined with mitral valve plasty resolved the left ventricular outflow tract obstruction and the clinical signs.     

Long‐term outcome in dogs undergoing mitral valve repair with suture annuloplasty and chordae tendinae replacement

Mitral valve repair under cardiopulmonary bypass was performed in three dogs with clinical signs associated with mitral regurgitation that were not controlled by medication. Mitral valve repair comprised circumferential annuloplasty and chordal replacement with expanded polytetrafluoroethylene. One dog died 2 years after surgery because of severe mitral regurgitation resulting from partial circumferential suture detachment. The others survived for over 5 years, but mild mitral valve stenosis persisted in one. The replaced chordae did not rupture in any dog. Mitral valve repair appears to be an effective treatment for mitral regurgitation in dogs. Chordal replacement with expanded polytetrafluoroethylene is a feasible technique, demonstrating long‐term durability in dogs. However, mitral annuloplasty techniques need improvement.     

Regurgitant fraction measured by using the proximal isovelocity surface area method in dogs with chronic myxomatous mitral valve disease

Previous studies have demonstrated that regurgitant fraction can be measured by using the proximal isovelocity surface area (PISA) method. For this study, we utilized this Doppler echocardiographic method to estimate the magnitude of mitral regurgitation in dogs with myxomatous mitral valve disease. Seventeen older, small dogs with chronic mitral regurgitation and no to mild myocardial failure were studied. A blinded observer judged the clinical severity of mitral regurgitation to be mild, moderate, or severe by using echocardiographic assessment of left heart size. The regurgitant fraction was calculated by using the PISA method and spectral Doppler echocardiography. The regurgitant fraction was compared to the clinical assessment of severity for each dog and to calculations of left atrial size. Five dogs had clinically mild mitral regurgitation. Four of these dogs had a regurgitant fraction between 22 and 41%, whereas 1 had a regurgitant fraction of 73%. The 3 dogs with clinical evidence of moderate mitral regurgitation had a regurgitant fraction of 46-65%. All 9 dogs with clinically severe mitral regurgitation had a regurgitant fraction greater than 75% (78-88%). The regurgitant fraction was statistically different between each group (P < .001). A good but curvilinear relationship was found between left atrial size and regurgitant fraction (r2 = 0.72). In this study, dogs with clinically severe mitral regurgitation consistently had hemodynamically severe regurgitation (regurgitant fraction > 75%), whereas dogs with clinically mild to moderate disease had lesser degrees of regurgitation. Good correlation was found between regurgitant fraction and left atrial size. We conclude that the major determinant of left atrial size and disease severity in dogs with mitrial regurgitation is the degree of mitral regurgitation.     

A case of juvenile form of dilated cardiomyopathy in a 6-month-old Shiba Inu dog

A 6-month-old Shiba Inu dog was brought to the Veterinary Medical Teaching Hospital because of a cough, exercise intolerance, and pulmonary edema. The dog had a Levine 2/6 systolic murmur. Transthoracic echocardiography revealed left atrial and ventricular dilatation (left atrium to aortic ratio: 2.8), mitral and tricuspid valve regurgitation, and severe left ventricular myocardial hypokinesia (fractional shortening was 11.8%). Bubble contrast echocardiography did not reveal a congenital shunt; therefore, the dog was clinically diagnosed with early onset dilated cardiomyopathy. From the first visit, the dog was treated with pimobendan, taurine, torasemide, and isosorbide dinitrate. After 435 days, echocardiography revealed that systolic function had not improved. On Day 465, atrial fibrillation was confirmed via electrocardiogram, and treatment with diltiazem hydrochloride was initiated. The dog continued to appear clinically stable thereafter, until it died suddenly 1087 days after the initial visit. A postmortem histopathological examination identified severe enlargement of the left atrial and ventricular chambers as well as attenuated wavy fibers in the ventricular myocardium, which confirmed dilated cardiomyopathy in a juvenile. This is the first report of a juvenile form of dilated cardiomyopathy in a Shiba Inu dog. This case report provides evidence that the extended prognosis of this dog differed from that in previously reported cases of dilated cardiomyopathy in young dogs.Key clinical message:This is the first reported case of a juvenile form of dilated cardiomyopathy in a Shiba Inu dog. This report provides evidence that the prognosis of this dog differed from that in previously reported cases of dilated cardiomyopathy in young dogs.     

Closed Transventricular Dilation of Discrete Subvalvular Aortic Stenosis in Dogs

Discrete subvalvular aortic stenosis with peak systolic pressure gradients of more than 60 mm Hg was treated by closed transventricular dilation in six young dogs. Peak systolic pressure gradients were measured by direct catheterization before surgery, immediately after dilation, and 3 months after surgery. Maximum instantaneous pressure gradients were measured by continuous wave Doppler echocardiography before surgery and 6 weeks to 9 months after surgery. All dogs survived the procedure, and two dogs were clinically normal after 9 and 14 months. Two dogs died at week 6 and month 7. One dog was receiving medication for pulmonary edema 15 months after surgery. One dog underwent open resection of the subvalvular ring at month 3, and was clinically normal 6 months after the second procedure. Complications included intraoperative ventricular fibrillation in one dog, and mild postoperative aortic insufficiency in one dog. Closed transventricular dilation resulted in an immediate 83% decrease in the peak systolic pressure gradient from a preoperative mean of 97 +/- 22 mm Hg to a mean of 14 +/- 15 mm Hg. However, systolic pressure gradients measured by direct catheterization at month 3 (77 +/- 26 mm Hg), and by Doppler echocardiography at week 6 to month 9 (85 +/- 32 mm Hg) were not significantly different from preoperative values, which suggested recurrence of the aortic stenosis. Closed transventricular dilation should not be considered a definitive treatment for discrete subvalvular aortic stenosis in dogs, but may be useful in young dogs with critical aortic stenosis as a bridge to more definitive surgery.     

Pulmonic stenosis in dogs: balloon dilation improves clinical outcome

Medical records of 81 dogs with severe pulmonic stenosis from 2 referral centers were examined retrospectively. Forty dogs underwent balloon valvuloplasty (BV), which was performed by 1 operator, whereas 41 did not. The mean age at latest follow-up was 41.5 months. A statistical comparison of the clinical outcome and survival was performed. Dogs revealing clinical signs at presentation showed a 16-fold increase in risk of death compared with asymptomatic dogs (P < .001). Statistical analyses demonstrated that an increase of 1 mm Hg in transstenotic pressure gradient (PG) at presentation was associated with a 3% increase in hazard rate (P < .001). Thirty-seven dogs survived BV with a median reduction in PG of 46%. The median preoperative PG was 120 mm Hg, and median PG 24 hours postoperatively was 55 mm Hg with a median of 55 mm Hg 6 months post-BV. Twenty (49%) of the non-BV (NBV) dogs remained asymptomatic at last follow-up. Fourteen (34%) of the NBV dogs died or were euthanized because of heart disease related to pulmonic stenosis. Twelve of these dogs died suddenly, whereas only 1 of the BV dogs died suddenly. After adjusting for PG, clinical signs at presentation, and age, BV or dilation was associated with a 53% reduction in hazard rate (P = .005). This study indicates that BV, when performed by an experienced operator, appears to be successful both in alleviating clinical signs and in prolonging survival in dogs with severe pulmonic stenosis.     

Use of a percutaneous atrial septal occluder device for complete acute occlusion of an intrahepatic portosystemic shunt in a dog

A 3-month-old sexually intact male German Shepherd Dog was evaluated because of signs of depression, ataxia, and collapse. Clinicopathologic abnormalities included low serum BUN and albumin concentrations and high serum liver enzyme activities and plasma ammonia and serum bile acids concentrations. Abdominal ultrasonography revealed an intrahepatic portosystemic shunt (PSS). The dog was anesthetized; via a transjugular approach, guidewires and catheters were directed with fluoroscopic guidance to locate the shunt and determine its anatomic features. Minimal changes in portal vein pressure during temporary shunt balloon occlusion enabled complete shunt attenuation, which was performed by use of a self-expanding septal occlusion device that is typically used for treatment of atrial septal defects in humans. Following initial misplacement of the device, the procedure was repeated successfully 2 months later and resulted in complete shunt occlusion. One year after this second procedure, the dog was clinically normal and serum bile acids concentration was within reference limits. In certain dogs with intrahepatic PSSs, treatment with minimally invasive interventional techniques involving fluoroscopy may reduce the morbidity and mortality rates associated with more invasive surgical procedures.