Prospective Evaluation of the Balloon-to-Annulus Ratio for Valvuloplasty in the Treatment of Pulmonic Stenosis in the Dog

Integrative echocardiographic assessment of post-operative obstruction severity and restenosis after balloon valvuloplasty in 81 dogs with pulmonary stenosis

INTRODUCTION/OBJECTIVES

Pulmonary stenosis (PS) is a congenital defect in the dog that is managed with balloon valvuloplasty (BV). Obstruction severity is routinely assessed using transthoracic echocardiography. The objectives of this study were to describe the short-term changes and long-term restenosis by retrospectively evaluating flow-dependent and flow-independent echocardiographic variables for dogs with PS after BV.

ANIMALS, MATERIALS, AND METHODS

Medical records and stored echocardiographic images were reviewed from dogs that received BV for PS. The following echocardiographic variables were measured or calculated: maximum systolic ejection velocity (Vmax_PV) and velocity-derived maximal pressure gradient (PV maxPG) across the pulmonary valve; ratio of aortic to pulmonary velocity time integral (VTI_AV/VTI_PV); ratio of aortic to pulmonary maximal velocity.

RESULTS

Eighty-one dogs with PS that had a BV were included. Each of these dogs had pulmonary obstruction severity assessed in at least three timepoints. Forty-nine dogs had at least one additional examination performed, the last of which occurred a median of 504 days after the BV. Echocardiographic variables at the first follow-up had increased by a clinically relevant quantity in 20-34% of the dogs when comparing to the immediate post-BV examination. The last follow-up examination identified valve restenosis in 18-38% of the dogs in this study. Valve type and pre-BV obstruction severity did not have a significant effect (P > 0.1).

CONCLUSIONS

For the assessment of BV efficacy, the immediate post-BV echocardiogram may not be as useful as the first follow-up examination several months later. Pulmonary restenosis after BV may be more prevalent than previously reported.

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.

Age of puppies at referral to veterinary cardiology specialists for murmur investigation

Background

Cardiac auscultation is an important screening test at the first health examination of puppies because most clinically relevant congenital cardiac anomalies cause a loud murmur from birth. This retrospective study aimed to investigate the age at which dogs with suspected congenital cardiac anomalies were referred to a veterinary cardiology specialist for murmur investigation. A secondary aim was to establish the time interval between the visit to the cardiologist and the first available murmur documentation. The digital archive of a veterinary teaching hospital was searched for dogs with congenital cardiac anomalies and puppies with innocent murmurs during a 5-year period. Dogs had to be referred because of a murmur, and they had to undergo physical examination and echocardiography by a veterinary cardiology specialist. The health certificate section of the pet passport, and the medical records from the referring veterinarian, were reviewed to identify the date when the murmur was first documented.

Results

Of the 271 included dogs, 94% had a congenital cardiac anomaly and 6% had an innocent murmur. The dogs’ median age was 190 days when they were examined by the cardiologist. Only 10% of the dogs were referred by the breeder’s veterinarian, while 90% of the dogs were referred by the new owner’s veterinarian. The median age of the first available murmur documentation by a first opinion veterinary practitioner was 95 days.

Conclusions

Only 10% of the puppies in the present study were referred to a veterinary cardiology specialist for murmur investigation before they were sold to a new owner. Referral prior to re-homing would have been feasible if the murmur had been detected and documented by the breeder’s veterinarian, if referral was offered by the breeder’s veterinarian and the referral was accepted by the breeder.

Long-term relief of obstruction in a dog with double-chambered right ventricle using combined cutting balloon and high-pressure balloon dilation

A 4-month-old intact female Golden Retriever dog was diagnosed with double-chambered right ventricle (DCRV) without infundibular stenosis, tricuspid valve dysplasia, and subsequent severe right atrial enlargement and was referred for combined cutting balloon and high-pressure balloon dilation. On presentation, these diagnoses were confirmed, and the peak systolic pressure gradient across the DCRV obstructive lesion assessed by continuous wave Doppler interrogation was 80 mm Hg. The obstructive lesion within the mid-right ventricle had a diameter of 6 mm through which blood flowed from the proximal right ventricular (RV) chamber to the distal RV chamber. The following day, general anesthesia was induced, and a minimally invasive balloon dilation was performed. A cutting balloon was inflated across the mid-RV obstructive lesion, followed by an inflation of a high-pressure balloon across this lesion. The high-pressure balloon catheter that was used had a diameter roughly 1.5 times the diameter of the pulmonary annulus. The following day, echocardiographic evaluation of the patient revealed a peak systolic pressure gradient across the DCRV obstructive lesion of 16 mm Hg, with a RV diameter at the level of obstruction of 11 mm. Twelve months later, the dog remains asymptomatic, right atrial size has decreased, and has a peak systolic pressure gradient across the DCRV lesion of 20 mm Hg.

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.

Immediate outcomes of low-pressure balloon valvuloplasty for severe pulmonary valve stenosis in 20 dogs: a retrospective, single-center case series

INTRODUCTION

The primary objective of this study was to describe the immediate post-procedural outcomes in dogs with severe pulmonary stenosis that were treated with low-pressure balloon valvuloplasty (BV) at a single institution.

ANIMALS, MATERIALS AND METHODS

Retrospective case series; medical records of dogs that underwent BV performed with a balloon dilation catheter >20 mm in diameter and a burst pressure of less than 4 atm (atm) were retrospectively reviewed. Twenty animals were identified fitting the criteria. Pre-procedural and post-procedural echocardiograms and peri-procedural angiograms were reviewed. Procedural success was defined as greater than 50% reduction in echocardiographically derived transpulmonary systolic pressure gradient (TPPG) or post-procedural TPPG of less than 50 mmHg.

RESULTS

The median percent reduction from initial TPPG was 53% (range = 15-90%). Sixty percent of the dogs met the pre-specified criteria for a successful outcome. Post-procedural TPPG was not different based on valve types A or B (p=0.67), presence or absence of additional supravalvular (p=0.23) or subvalvular (p=0.83) obstructive components.

DISCUSSION

The proportion of dogs that reach the successful outcome were not different based on valve type A or B. No relationship was noted between immediate outcomes and bodyweight or pulmonary annulus diameter.

CONCLUSION

Dogs with severe pulmonic stenosis that underwent low-pressure BV had good immediate outcomes with no difference in outcome based on valve morphology. Further randomized controlled studies are needed to compare the outcomes of different strategies for BV in dogs with large-diameter pulmonary annulus.

Repeat balloon valvuloplasty for dogs with recurrent or persistent pulmonary stenosis

INTRODUCTION/OBJECTIVES

Pulmonary stenosis (PS) is a common congenital defect in the dog. Severe valvar PS can be treated with balloon valvuloplasty (BV) to reduce obstruction severity and improve clinical signs. Repeat BV is often unnecessary, as restenosis is uncommon. Repeated pulmonary BV in people is generally successful and safe, but outcomes in dogs with recurrent or persistent stenosis have not been reported. The objectives of this study were to retrospectively evaluate outcomes of repeat BV in dogs.

ANIMALS, MATERIALS, AND METHODS

Medical records and stored echocardiographic images were reviewed from dogs that received repeat BV for pulmonary valvar restenosis or persistent stenosis. Echocardiographic variables included maximum systolic ejection velocity (PVmax), velocity-derived maximal pressure gradient (PGmax) and velocity time integral (VTI) across the pulmonary valve, and ratios of pulmonic to aortic maximum velocity (PVmax/AVmax) and VTI (VTI_PV/VTI_AV).

RESULTS

Twenty-three dogs were included; one underwent three BV procedures. The median time between BV procedures was 18.3 months (interquartile range, 6.3-43.6). One dog died during repeat BV, but no others experienced adverse effects. Reductions in PVmax, PGmax, and VTI_PV after initial and repeat BV were 1.85 m/s, 76.2 mmHg, and 44.7 cm and 1.33 m/s, 55.6 mmHg, and 30.2 cm, respectively (all p < 0.01). Differences between pre-BV and post-BV PVmax, PGmax, VTI_PV, PVmax/AVmax, and VTI_PV/VTI_AV were not different comparing initial to repeat BV (all p > 0.10).

CONCLUSIONS

Repeat BV for recurrent or persistent PS is well tolerated and effective in a majority of dogs.

Combined cutting balloon and conventional balloon angioplasty in a dog with supravalvular pulmonary stenosis

A 7-year-old Miniature Schnauzer presented with exercise intolerance and easy fatigability. Echocardiography revealed the presence of supravalvular pulmonary stenosis. The peak velocity through the stenosis was 6.4 m/sec, and the interventricular septum was flattened. Cutting balloon angioplasty was designed for the treatment of coronary artery stenosis, which was resistant to conventional balloon angioplasty. Accordingly, the dog underwent cutting balloon angioplasty and conventional balloon dilation. One month after treatment, it showed neither exercise intolerance nor easy fatigability. The ventricular septum flattening disappeared. Five months later, the dog showed an increase in activity. Two years later, the peak velocity through the stenosis decreased to 4.4 m/sec. Neither clinical symptoms nor restenosis was observed. Thus, supravalvular pulmonary stenosis was successfully treated using this combination method. The present case showed that combined cutting balloon and conventional balloon angioplasty is a useful and minimally invasive treatment for supravalvular pulmonary stenosis.

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.

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.

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.

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.

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 x 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 < or = .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.