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

Balloon valvuloplasty in 2 juvenile alpacas with severe valvular pulmonic stenosis

Two juvenile alpacas, 1 male and 1 female, were presented for evaluation of grade V/VI bilateral basilar systolic heart murmurs. Both animals were ultimately diagnosed with severe valvular pulmonic stenosis and a small ventricular septal defect. Transvenous balloon valvuloplasty was performed in each animal using methods described in the dog. A double balloon technique was employed in the first case, with a balloon‐annulus ratio of ~1.55. For the second case, a high‐pressure dilatation balloon catheter with a balloon‐annulus ratio of ~1.33 was selected. Experience with both procedures indicates that balloon pulmonary valvuloplasty is technically feasible in alpacas using techniques extrapolated from those used in dogs. Furthermore, accepted criteria for procedural success were fulfilled for both alpacas, with more than a 50% reduction in the echocardiographically derived transpulmonic pressure gradient after intervention.

Reference intervals for transthoracic echocardiography in the American Staffordshire Terrier

This study reports the echocardiographic reference intervals in the American Staffordshire Terrier (AST). The echocardiographic variables obtained in 57 healthy adult AST were compared with published data from the general canine population and other breeds. In the AST, the left ventricular volumes were lower than values reported in Boxers and Dobermans (P<0.0001), but higher than in small breeds (P<0.0001). The left ventricular ejection fraction was higher than Boxers and Dobermans (P<0.0001), but lower than small breed dogs (P=0.027). The aortic peak velocity values were similar to Boxers (P=0.55) but higher than the general canine population (P<0.0001). The reference intervals presented in this study are clinically useful for an accurate echocardiographic interpretation and screening in the AST.

Transoesophageal echocardiography-guided hybrid balloon valvuloplasty for severe pulmonic stenosis in small dogs

Pulmonic stenosis (PS) is the most common congenital heart disease in dogs and is commonly seen in small breeds, such as Chihuahuas. Conventional treatments have limitations specific to small dogs, including the invasive nature of open-heart surgery and size limitations in percutaneous balloon valvuloplasty. Here, transoesophageal echocardiography (TEE)-guided balloon valvuloplasty via thoracotomy was performed for three small dogs with PS. The procedure was feasible in all cases, including those for which percutaneous treatment was not an option. Although the procedure is invasive, because of the need for thoracotomy, it is one of the treatment options that may be effective for PS, especially in small dogs, as it allows visualisation of the pulmonary artery lesion without relying on the experience of the surgeon.

Left ventricular systolic function in dogs with pulmonic stenosis

Background and Aim:

Pulmonic stenosis (PS) is the most common congenital heart disease in dogs. This condition causes right ventricle (RV) overload and disrupts overall systolic function. The aim of this study was to examine the alterations of cardiac electrical activity and mechanical function in dogs with PS compared to normal healthy dogs.

Materials and Methods:

The ventricular systolic function of dogs with PS was studied. Dogs were divided into two groups, PS (n=13) and control (CONT) (n=12). Measurements of blood pressure, electrocardiography (ECG), and echocardiography were performed.

Results:

PS dogs had exercise intolerance, with six experiencing syncope. ECG of PS dogs showed higher amplitudes of P, S, and T waves (p<0.01), and a lower R:S ratio (p<0.001) with longer QRS duration (p<0.001) compared to CONT dogs. Echocardiography demonstrated that the pulmonic flow velocity and pressure gradient (PG) between the RV and the pulmonary artery of PS dogs were significantly higher than CONT dogs (p<0.001). The RV free wall thickness to the left ventricular posterior wall thickness ratio and the right atrium to the left atrium diameter ratio was higher (p<0.001), while interventricular septum (IVS) was thicker (p<0.01) in PS dogs compared with CONT dogs (p<0.001). The systolic function in PS dogs showed higher pulmonic valve velocity time integral (PVVTI) value (p<0.001) and longer pulmonic valve ejection time (ET) (p<0.05) than CONT dogs. However, aortic valve VTI (AVVTI) value and aortic valve ET were not significantly different between the groups, although fractional shortening in PS dogs was higher. In PS dogs, PG showed a significant positive correlation with PVVTI: AVVTI ratio (p<0.05).

Conclusion:

PS had prolonged pulmonic valve opening. The thickening of the RV wall and IVS can cause a detrimental reduction of the left ventricular preload in PS dogs.

Epidemiological study of congenital heart diseases in dogs: Prevalence, popularity, and volatility throughout twenty years of clinical practice

The epidemiology of Congenital Heart Diseases (CHDs) has changed over the past twenty years. This study aimed to evaluate the prevalence of CHDs in the population of dogs recruited in a single referral center (RC); compare the epidemiological features of CHDs in screened breeds (Boxers) versus non-screened (French and English Bulldogs, German Shepherds); investigate the association of breeds with the prevalence of CHDs; determine the popularity and volatility of breeds over a 20-year period; analysed the trends of the most popular breeds in the overall population of new-born dogs registered in the Italian Kennel Club (IKC) from 1st January 1997 to 31st December 2017. The RC's cardiological database was analysed, and 1,779 clinical records were included in a retrospective observation study. Descriptive statistics and frequencies regarding the most representative breeds and CHDs were generated. A logistic regression model was used to analyse the trends of the most common CHDs found in single and in cluster of breeds. The relationship between breed popularity and presence of CHDs was studied. The most common CHDs were Pulmonic Stenosis, Patent Ductus Arteriosus, Subaortic Stenosis, Ventricular Septal Defect, Aortic Stenosis, Tricuspid Dysplasia, Atrial Septal Defect, Double Chamber Right Ventricle, Mitral Dysplasia, and others less frequent. The most represented pure breeds were Boxer, German Shepherd, French Bulldog, English Bulldog, Maltese, Newfoundland, Rottweiler, Golden Retriever, Chihuahua, and others in lower percentage. Chihuahuas, American Staffordshire Terriers, Border Collies, French Bulldogs, and Cavalier King Charles Spaniel were the most appreciated all of which showed a high value of volatility. This study found evidence for the value of the screening program implemented in Boxers; fashions and trends influence dog owners' choices more than the worries of health problems in a breed. Effective breeding programs are needed in order to control the diffusion of CHDs without impoverishing the genetic pool.

Combined interventional procedure and cardiopulmonary bypass surgery in a dog with cor triatriatum dexter, patent foramen ovale, and pulmonary stenosis

A 2‐year‐old American Pit Bull dog was presented for surgical evaluation of imperforate cor triatriatum dexter (CTD) and patent foramen ovale (PFO). Echocardiography identified an imperforate CTD associated with a right‐to‐left shunting PFO and valvular pulmonary stenosis. A 2‐step interventional and surgical approach was used. Initially, a pulmonary balloon valvuloplasty was performed, and subsequently the dog underwent a surgical correction of the atrial anomaly under cardiopulmonary bypass.

Congenital Cardiac Outflow Tract Abnormalities in Dogs: Prevalence and Pattern of Inheritance From 2008 to 2017

Subvalvular aortic stenosis (SAS) and valvular pulmonic stenosis (PS) are two of the most common congenital heart diseases of dogs. The aim of this study was to determine the prevalence and mode of inheritance of these congenital heart diseases in a large veterinary teaching hospital population. Case records of dogs presented to the University of California Davis, Veterinary Medical Teaching Hospital (UCD VMTH) between January 2008 to December 2017 were reviewed retrospectively and pedigree information was obtained when available. There were 259 unique SAS and 336 unique PS cases diagnosed during the study period. The prevalence of SAS was 0.3% of overall hospital admissions and 4.7% for all dogs seen by the cardiology service. The prevalence for PS was 0.41% of overall hospital admissions and 6.1% of dogs seen by the cardiology service. Bullmastiffs and Newfoundlands had the greatest prevalence (6.59 and 4.46%, respectively) and odds ratio (52.43 and 34.73, respectively) for SAS. Bulldogs and French Bulldogs had the greatest prevalence (4.8 and 2.7%, respectively) and odds ratio (13.32 and 7.52, respectively) for PS. The identified prevalence of SAS and PS is higher than previously reported. Pedigree analysis in SAS affected Bullmastiffs, Golden Retrievers, and Rottweilers suggested an autosomal recessive pattern of inheritance. The mode of inheritance for PS in Bulldogs, also appears to be autosomal recessive. The results of this study can be used to inform future selection of breeding pairs and genetic studies aimed at reducing the prevalence of these common congenital heart diseases.

Echocardiographic evaluation of velocity ratio, velocity time integral ratio, and pulmonary valve area in dogs with pulmonary valve stenosis

Background

Velocity ratio, velocity time integral (VTI) ratio, and pulmonary valve area indexed to body surface area (iPVA) are methods of assessment of pulmonary valve stenosis (PS) severity that are less dependent on blood flow. Studies evaluating these methods are limited.

Objectives

To determine the effects of butorphanol, atenolol, and balloon valvuloplasty (BV) on velocity ratio, VTI ratio, iPVA, mean PG, and max PG.

Animals

Twenty‐seven dogs with PS (max PG >50 mm Hg).

Methods

Prospective study. All dogs underwent an echocardiogram at baseline, 5‐minutes after administration of butorphanol (0.2‐0.25 mg/kg IV), and 2‐to‐4 weeks after atenolol (1‐1.5 mg/kg q12h). Twenty‐one of these were evaluated 24‐hours after BV.

Results

There were no significant differences (P > .05) amongst any of the methods of assessment of PS severity after butorphanol. After atenolol, mean (SD) of mean (57.0 [21.0] mm Hg) and max PG (93.1 [33.8] mm Hg) were significantly decreased (P ≤ .047) compared with baseline (65.2 [26.2] mm Hg and 108 [44.4] mm Hg, respectively). After atenolol, there were no significant (P ≥ .12) differences in velocity ratio (0.29 [0.09]), VTI ratio (0.18 [0.05]), or iPVA (0.43 [0.16] cm²/m²) compared with baseline (0.30 [0.09], 0.19 [0.09], 0.44 [0.17] cm²/m², respectively).

Conclusions and Clinical Importance

Atenolol might reduce mean and max PG but does not alter less flow‐dependent methods of assessment of PS severity (velocity ratio, VTI ratio, and iPVA) in dogs with PS. Results support an integrative approach to assessment of PS severity that includes less flow‐dependent methods, particularly in states of altered flow or right ventricular function.

Anatomic, histopathologic, and echocardiographic features in a dog with an atypical pulmonary valve stenosis with a fibrous band of tissue and a patent ductus arteriosus

Background

Congenital pulmonary valve stenosis and patent ductus arteriosus are common congenital heart defects in dogs. However, concurrence of atypical pulmonary valve stenosis and patent ductus arteriosus is uncommon. This report describes the anatomic, histopathologic, and echocardiographic features in a dog with concomitant pulmonary valve stenosis and patent ductus arteriosus with atypical pulmonary valve dysplasia that included a fibrous band of tissue.

Case presentation

A 1.5-year-old intact female Chihuahua dog weighing 3.3 kg presented with a continuous grade VI cardiac murmur, poor exercise tolerance, and an intermittent cough. Echocardiography indicated pulmonary valve stenosis, a thickened dysplastic valve without annular hypoplasia, and a type IIA patent ductus arteriosus. The pulmonary valve was thick line-shaped in systole and dome-shaped towards the right ventricular outflow tract in diastole. The dog suffered a fatal cardiac arrest during an attempted balloon pulmonary valvuloplasty. Necropsy revealed pulmonary valve dysplasia, commissural fusion, and incomplete opening and closing of the pulmonary valve because of a fibrous band of tissue causing adhesion between the right ventricular outflow tract and the dysplastic intermediate cusp of the valve.

Conclusions

A fibrous band of tissue between the right ventricular outflow track and the pulmonary valve should be considered as a cause of pulmonary valve stenosis. Pulmonary valve stenosis and patent ductus arteriosus can have conflicting effects on diastolic and systolic dysfunction, respectively. Therefore, beta-blockers should always be used carefully, particularly in patients with a heart defect where there is concern about left ventricular systolic function.

Restenosis after balloon valvuloplasty in a dog with pulmonary stenosis

A two-month-old female Chihuahua was diagnosed as severe pulmonary valvular stenosis (PS). Although balloon valvuloplasty (BV) was successfully performed, restenosis was observed 19 months after the procedure. Euthanasia was chosen due to low output syndrome during the surgical repair attempted when the dog was 5 years old. Postmortem examination revealed markedly thickened pulmonary valve due to the increase of extracellular matrix which might be produced by increased α smooth muscle actin-positive myofibroblasts. The thickening of the valve was associated with restriction of the valve's motion, resulting in restenosis in the present case. This is the first case report documented histopathological and immunohistochemical findings of the restenotic pulmonary valve in dogs with PS after BV.

Plasma N-terminal pro B-type natriuretic peptide concentrations in dogs with pulmonic stenosis

The detailed information between plasma N-terminal pro B-type natriuretic peptide (NT-proBNP) concentrations and dogs with pulmonic stenosis (PS) is still unknown. The aim of the present study was to investigate the clinical utility of measuring plasma NT-proBNP concentrations in dogs with PS and to determine whether plasma NT-proBNP concentration could be used to assess disease severity. This retrospective study enrolled 30 client-owned, untreated dogs with PS (asymptomatic [n=23] and symptomatic [n=7]) and 11 healthy laboratory beagles. Results of physical examination, thoracic radiography and echocardiography were recorded. Plasma NT-proBNP concentrations were measured using commercial laboratories. Compared to the healthy control dogs, cardiothoracic ratio was significantly increased in dogs with both asymptomatic and symptomatic PS. Similarly, the ratio of the main pulmonary artery to aorta was significantly decreased in dogs with both asymptomatic and symptomatic PS. The pulmonic pressure gradient in the symptomatic PS dogs was significantly higher than that in the asymptomatic PS dogs. Plasma NT-proBNP concentration was significantly elevated in the symptomatic PS dogs compared to the healthy control dogs and the asymptomatic PS dogs. Furthermore, the Doppler-derived pulmonic pressure gradient was significantly correlated with the plasma NT-proBNP concentration (r=0.78, r(2)=0.61, P<0.0001). Plasma NT-proBNP concentration >764 pmol/l to identify severe PS had a sensitivity of 76.2% and specificity of 81.8%. The plasma NT-proBNP concentration increased by spontaneous PS, i.e. right-sided pressure overload and can be used as an additional method to assess the severity of PS in dogs.

Histological study of right ventricle-pulmonary artery valved conduit implantation (RPVC) in dogs with pulmonic stenosis

We examined whether right ventricle-pulmonary artery valved conduit (RPVC) implantation can overcome the disadvantages of current procedures for pulmonic stenosis (PS). We histologically evaluated the feasibility of RPVC using a homograft in PS model dogs. Eight dogs underwent pulmonary artery banding (PAB) and then 12 weeks later were assigned to PAB (n=4) or PAB+RPVC (n=4) groups. Dogs in the PAB group received no treatment throughout the experimental period, whereas the PAB+RPVC group underwent RPVC. At 1 year after PAB, hearts and conduits were explanted from euthanized dogs and histologically evaluated. The ratios (%) of myocardial fibrosis on right ventricle (RV) epicardial, median and endocardial layers were significantly lower in the PAB+RPVC, than in the PAB group. The ratio of myocardial fibrosis on left ventricular (LV) epicardial and endocardial layers were significantly lower in the PAB+RPVC, than in the PAB group. Neo-intimal thickness in the anastomosis areas of the Denacol and PAB+RPVC groups was 42.77 +/- 30.19 and 88.30 +/- 27.24 microm, respectively, with no significant differences between the groups. Calcification and neo- intima hypertrophy were not obvious in the valve area. Immunohistological staining showed that the internal surface of the anastomosis and intermediate areas were positive for endothelial cells. We concluded that RPVC using a bioprosthetic graft can apparently overcome the disadvantages of current procedures for pulmonic stenosis.

Cardiovascular effects of right ventricle-pulmonary artery valved conduit implantation in experimental pulmonic stenosis

Right ventricle (RV)-pulmonary artery (PA) valved conduit (RPVC) implantation decreases RV systolic pressure in pulmonic stenosis (PS) by forming a bypass route between the RV and the PA. The present study evaluates valved conduits derived from canine aortae in a canine model of PS produced by pulmonary artery banding (PAB). Pulmonary stenosis was elicited using PAB in 10 conditioned beagles aged 8 months. Twelve weeks after PAB, the dogs were assigned to one group that did not undergo surgical intervention and another that underwent RPVC using denacol-treated canine aortic valved grafts (PAB+RPVC). Twelve weeks later, the rate of change in the RV-PA systolic pressure gradient was significantly decreased in the PAB+RPVC, compared with the PAB group (60.5 +/- 16.7% vs. 108.9 +/- 22.9%; p<0.01). In addition, the end-diastolic RV free wall thickness (RVFWd) was significantly reduced in the PAB+RPVC, compared with the PAB group (8.2 +/- 0.2 vs. 9.4 +/- 0.7 mm; p<0.05). Thereafter, regurgitation was not evident beyond the conduit valve and the decrease in RV pressure overload induced by RPVC was confirmed. The present results indicate that RPVC can be performed under a beating heart without cardiopulmonary bypass and adapted to dogs with various types of PS, including "supra valvular" PS or PS accompanied by dysplasia of the pulmonary valve. Therefore, we consider that this method is useful for treating PS in small animals.

Pulmonic stenosis in two cats

The clinical, radiographic and echocardiographic features of two cases of pulmonic stenosis in cats are presented. A rarely reported combination of pulmonic stenosis and tricuspid valve dysplasia is described.

Evaluation of closed pericardial patch grafting for management of severe pulmonic stenosis

Closed pericardial patch-grafting has been advocated for the treatment of severe pulmonic stenosis. In this study pre- and postoperative echocardiography was used to determine if the transvalvular pressure gradient was successfully lowered by this surgery and whether it remained lowered long term. The valvulotomy-ventriculectomy wire was passed using a blunt needle in four dogs (Bresnock technique1) and via a soft catheter in five dogs (Shores and Weirich modification). Eight of nine patients survived the perioperative period. These dogs were assessed up to 40 months following surgery for clinical and echocardiographic changes. Five cases showed significant decrease in peak pulmonic pressure gradient immediately after surgery (decreasing by 50-81%, P < 0.05), and six cases showed significant decrease 2 to 40 months postoperatively (decreasing by 31-80%, P < 0.005) when compared to preoperative values. There was no significant change in pulmonic pressure gradient from immediately postoperatively to 2 to 40 months postoperatively (P < 0.48). Six dogs showed clinical improvement postoperatively, however persistent right ventricular hypertrophy was observed in all cases. One dog died with symptoms of congestive heart failure 16 months postoperatively. Closed pericardial patch grafting can improve clinical signs in symptomatic patients, however the surgery has significant risks, long term prognosis for these patients is guarded and recurrence of clinical signs and development of congestive heart failure is possible. Cardiac changes can be monitored with Doppler flow echocardiography. Patients with extremely elevated preoperative pressure gradients may be expected to have poorer outcomes.