Transcatheter intravascular stent placement to relieve supravalvular pulmonic stenosis

Effect of preoperative administration of atenolol to dogs with pulmonic stenosis undergoing interventional procedures

Background

Beta‐blockade is sometimes used in dogs with pulmonic stenosis with the intent of reducing frequency of ventricular arrhythmias during right heart catheterization.

Objectives

To evaluate if pretreatment with atenolol reduces frequency of ventricular arrhythmias, anesthetist interventions, or shortens procedure time.

Animals

Thirty dogs with pulmonic stenosis scheduled for interventional procedures.

Methods

Single center, prospective, randomized, open‐label study. Dogs were randomized to treatment with atenolol or no treatment preoperatively for a minimum of 10 days. Variables recorded included heart rate, arrhythmias and complexity, total procedure time and administration of antiarrhythmic treatment, vasopressors, positive chronotropes, or fluid boluses.

Results

Fifteen dogs were enrolled in each group. Dogs receiving atenolol had lower mean heart rates during the procedure (atenolol 100 ± 11 bpm vs untreated 115 ± 19 bpm, P = .01). There were no significant differences between the atenolol and untreated groups in the frequency of ventricular ectopic complexes (535 [6‐5296] vs 553 [79‐2863], P = .9), ventricular couplets (46 [0‐481] vs 29 [3‐121], P = .59), ventricular triplets (20 [0‐265] vs 16 [1‐82], P = .67), ventricular tachycardia (8 [0‐224] vs 8 [1‐118], P = .99), proportion exhibiting R‐on‐T phenomenon (11/15 vs 14/15, P = .33), proportion receiving intraoperative lidocaine (1/15 vs 3/15, P = .6), vasopressors/positive chronotropes (11/15 vs 5/15, P = .06), or fluid boluses (12/15 vs 7/15, P = .13). The procedure time was similar (atenolol 41 [23‐68] min vs untreated 35 [18‐98] min, P = .91).

Conclusions and Clinical Importance

No benefit of preoperative atenolol treatment was identified in this small group of dogs.

Transvalvular pulmonic stent angioplasty: procedural outcomes and complications in 15 dogs with pulmonic stenosis

INTRODUCTION

Balloon valvuloplasty is the treatment of choice for dogs with severe type A pulmonic stenosis (PS), but less successful for dogs with annular hypoplasia and unsuitable for supravalvular stenosis or cases with a circumpulmonary coronary malformation. We report outcomes and complications of the first 15 consecutive transvalvular pulmonic stent angioplasty procedures performed by a single center in dogs with PS.

ANIMALS

Fifteen dogs with naturally occurring PS were included in the study.

MATERIALS AND METHODS

Dogs underwent echocardiography before and four weeks after the procedure. Transvenous approaches were used to deploy a pre-mounted, balloon-expandable metallic stent in all cases.

RESULTS

Of 15 dogs, all had annular hypoplasia, and in addition, supravalvular stenosis was diagnosed in 11 of 15 dogs, and three had R2A coronary malformation. All dogs survived to discharge. One dog died less than four weeks postoperatively (non-cardiac), but 14 of 15 dogs were re-examined at four weeks. Severity reduced in all cases; median pressure gradient reduced from 137 mmHg (range 81-202 mmHg) to 83 mmHg (range 31-155 mmHg). Clinical signs improved in all cases, and hematocrit reduced in all dogs with erythrocytosis. The median follow-up time was 280 days (range 95-896 days). Over one-year follow-up was available in six of fifteen dogs. Two dogs died because of refractory right-sided congestive heart failure signs: one at 10 months and one at 22 months postoperatively.

CONCLUSIONS

Transvalvular pulmonic stent angioplasty technique was associated with an improvement in clinical signs and reduction in stenosis severity for all dogs in this population, including cases with supravalvular PS or circumpulmonary coronary malformation.

A novel hybrid stent technique to treat canine pulmonic stenosis

Balloon valvuloplasty is routinely performed in dogs with severe pulmonic stenosis using a transvenous approach. We report a novel transventricular approach to stent the right ventricular outflow tract. An 18-month old Havanese with frequent syncope was referred with a diagnosis of severe valvular pulmonic stenosis. Transvenous approaches were unsuccessful; therefore, two Palmaz XL 29 mm by 12 mm transhepatic biliary stents were deployed across the valve using a direct right ventricular approach. The echocardiographically derived systolic pressure gradient decreased from 133 mmHg to 39 mmHg with resolution of clinical signs. The patient continues to do well after 3 years with occasional syncope when extremely excited despite pressure gradient increases to 130 mmHg at 12 months and 174 mmHg at 22 months.

Treatment of caudal cavoatrial junction obstruction in a dog with a balloon-expandable biliary stent

A 2-year-old intact female mixed breed dog was presented for ascites. Echocardiography demonstrated severe obstruction at the level of the caudal right atrium. Initially, a variant of cor triatriatum dexter was diagnosed, and balloon catheter dilation was performed. However, ascites recurred within a week. Further imaging revealed an obstruction at the entrance of the caudal vena cava into the right atrium rather than a dividing membrane in the right atrium. The diagnosis was revised to suprahepatic obstruction of the caudal vena cava because of remnant Eustachian valve tissue. Deployment of a balloon-expandable biliary stent was performed relieving the obstruction. Fifteen months after stent deployment, the patient is doing well without reaccumulation of ascitic fluid.

Balloon dilation of congenital supravalvular pulmonic stenosis in a dog

Percutaneous balloon valvuloplasty is considered the standard of care for treatment of valvular pulmonic stenosis, a common congenital defect in dogs. Supravalvular pulmonic stenosis is a rare form of pulmonic stenosis in dogs and standard treatment has not been established. Although, there have been reports of successful treatment of supravalvular pulmonic stenosis with surgical and stenting techniques, there have been no reports of balloon dilation to treat dogs with this condition. Here, a case of supravalvular pulmonic stenosis diagnosed echocardiographically and angiographically in which a significant reduction in pressure gradient was achieved with balloon dilation alone is presented.

Minimally invasive per-catheter occlusion and dilation procedures for congenital cardiovascular abnormalities in dogs

With ever-increasing sophistication of veterinary cardiology, minimally invasive per-catheter occlusion and dilation procedures for the treatment of various congenital cardiovascular abnormalities in dogs have become not only available, but mainstream. Much new information about minimally invasive per-catheter patent ductus arteriosus occlusion has been published and presented during the past few years. Consequently, patent ductus arteriosus occlusion is the primary focus of this article. Occlusion of other less common congenital cardiac defects is also briefly reviewed. Balloon dilation of pulmonic stenosis, as well as other congenital obstructive cardiovascular abnormalities is discussed in the latter part of the article.

Juxtaductal Coarctation of Both Pulmonary Arteries in a Cat

A 4-year-old, male, neutered cat was referred because of recurrent episodes of dyspnea. Physical examination revealed a harsh systolic murmur, with the point of maximal intensity in the left heart base, with an intensity of 4 out of 6. Echocardiographic diagnosis was severe supravalvular pulmonary artery stenosis. A selective right ventricular angiocardiogram showed an absence of arterial blood flow to the left lung lobes. A balloon dilatation of the localized stenosis of the right pulmonary artery was attempted with cardiac catheterization. However, when the catheter was passed through the stenosis, the blood flow to the lungs temporarily completely ceased, which led to death. Postmortem examination revealed a circumscribed stenosis of both pulmonary arteries at the site of the bifurcation, where the ligamentum arteriosum was attached. Histopathology showed that the localized ridge-like stenosis at the pulmonary artery bifurcation was caused by connective tissue. The suspected cause of this congenital anomaly is the presence of ectopic ductal tissue in the wall of the pulmonary artery. When the ductus arteriosus closes at birth, pulmonary artery stenosis developed because of constriction of the ectopic ductal tissue.

Acquired pulmonary artery stenosis in four dogs

CASE DESCRIPTION

4 dogs with acquired pulmonary artery stenosis (PAS) were examined for various clinical signs. One was a mixed-breed dog with congenital valvular PAS that subsequently developed peripheral PAS, one was a Golden Retriever with pulmonary valve fibrosarcoma, one was a Pembroke Welsh Corgi in which the left pulmonary artery had inadvertently been ligated during surgery for correction of patent ductus arteriosus, and one was a Boston Terrier with a heart-base mass compressing the pulmonary arteries.

CLINICAL FINDINGS

All 4 dogs were evaluated with 2-dimensional and Doppler echocardiography to characterize the nature and severity of the stenoses; other diagnostic tests were also performed.

TREATMENT AND OUTCOME

The mixed-breed dog with valvular and peripheral PAS was euthanized, surgical resection of the pulmonic valve mass was performed in the Golden Retriever, corrective surgery was performed on the Pembroke Welsh Corgi with left pulmonary artery ligation, and the Boston Terrier with the heart-base mass was managed medically.

CLINICAL RELEVANCE

Acquired PAS in dogs may manifest as a clinically silent heart murmur, syncope, or right-sided heart failure. The diagnosis is made on the basis of imaging findings, particularly results of 2-dimensional and Doppler echocardiography. Treatment may include surgical, interventional, or medical modalities and is targeted at resolving the inciting cause.