Balloon Valvuloplasty of Valvular Pulmonic Stenosis in the Dog

64-Slice ECG-gated computed tomographic angiography for assessment of coronary arteries in brachycephalic dogs with pulmonary stenosis

BACKGROUND

Brachycephalic dogs with pulmonary stenosis are known to have a higher incidence of concurrent coronary artery abnormalities than non-brachycephalic breeds, which increases risk when performing balloon valvuloplasty. The use of ECG-gated CT angiography has been reported for the evaluation of coronary arteries in normal dogs and dogs with pulmonary stenosis. The purpose of this study was to report findings of coronary artery origination and morphology of main branches using ECG-gated CT angiography in brachycephalic dogs with pulmonary stenosis.

METHODS

An ECG-gated CT angiographic protocol was used to image coronary artery anatomy in nine brachycephalic dogs with pulmonary stenosis. Images were assessed for quality as well as coronary artery morphology by one veterinary radiologist, one veterinary cardiologist and one veterinary radiology resident.

RESULTS

All nine dogs had good to excellent image quality. Coronary artery anomalies were identified in three of nine dogs: one R2A anomaly, one L2A anomaly and one L2C anomaly. Two dogs were assessed to be poor balloon valvuloplasty candidates based on CT angiographic images.

LIMITATION

Coronary artery morphology was not confirmed via postmortem examination in all patients.

CONCLUSION

ECG-gated CT angiography is a minimally invasive imaging modality capable of diagnosing various coronary artery anomalies in brachycephalic dogs with pulmonary stenosis and aiding in the determination of patient candidacy for balloon valvuloplasty.

Non-deflating balloon during pulmonary valvuloplasty

A 3-year-old, 4.8 kg, male intact, mixed breed dog was referred for balloon pulmonary valvuloplasty (BPV). Echocardiography was consistent with severe type A pulmonic stenosis and BPV was recommended. During BPV, the balloon catheter failed to deflate despite multiple attempts at repositioning and the use of different deflation syringes. After approximately two minutes of cardiopulmonary arrest, forceful retrograde traction resulted in removal of the fully inflated balloon. Cardiopulmonary resuscitation was unsuccessful. Post-mortem evaluation by a board-certified pathologist identified rupture of the cranial vena cava and hemothorax, suspected to be secondary to forceful removal of the fully inflated balloon. Manufacturer's evaluation of the balloon catheter used in the procedure identified multiple kinks and a segment of stretched catheter shaft suspected to be the cause for the inability to deflate. A manufacturing defect present prior to use or predisposing to stretching of the catheter segment could not be ruled out. Kinking and/or stretching of the catheter during BPV were possible causes as well. Although the inability to deflate a balloon catheter seems to be a very rare occurrence, it should be considered as a potential complication of BPV.

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.

Transjugular Patent Ductus Arteriosus Occlusion in Seven Dogs Using the Amplatzer Vascular Plug II

Simple Summary

This study outlines the authors’ experience using the Amplatzer Vascular Plug II device for occlusion of patent ductus arteriosus (PDA) in dogs through a right transjugular approach, never before described in veterinary medicine for this purpose. The obtained results demonstrate that the use of the Amplatzer Vascular Plug II via a transvenous right jugular approach is a feasible and effective method, even in small-sized patients. The authors’ experience is that the transvenous approach is a safe and effective method for PDA occlusion in dogs. Furthermore, the right jugular approach provides easier and faster vascular access than the femoral one. The authors affirm that this approach, together with the properties of the Amplatzer Vascular Plug II and its wide size selection, potentially provide a novel method that can complement the current available methods for transcatheter PDA occlusion.

Abstract

Although vascular plugs for the closure of patent ductus arteriosus (PDA) have been validated in dogs, studies are lacking on its use as a first-choice device with a transjugular approach. The present case series describes the transvenous right jugular embolization of PDA using an Amplatzer Vascular Plug II in seven dogs of different ages, breeds, and body weights. Complete closure of the PDA was demonstrated in all cases. All dogs showed significant hemodynamic reduction of pulmonary overcirculation and left heart size after the procedure and at following echocardiographic check-ups. Transjugular PDA occlusion using an Amplatzer Vascular Plug II can thus be considered as a safe alternative to the arterial or venous femoral approach using an Amplatzer canine ductal occluder (ACDO), particularly in puppies with small femoral vessels.

Abnormalities of External Jugular Veins in Bulldogs with Pulmonary Valve Stenosis

Simple Summary

This case series is about two French bulldogs and one English bulldog affected by pulmonary valve stenosis that were diagnosed with different abnormalities of the external jugular veins (EJV) before a pulmonary balloon valvuloplasty. The EJV abnormalities encountered were severe hypoplasia of both external jugular veins and right external jugular vein absence, associated with persistent left cranial vena cava. All cases were diagnosed through computed tomography and vascular ultrasound. The aim of this case series is to describe external jugular veins abnormalities that can affect the decision-making process regarding central venous catheterization needed to perform procedures such as pulmonary balloon valvuloplasty or central catheter placement. Based on the results of the present case series, anomalies of the external jugular veins should be considered in French and English bulldogs when the external jugular veins cannot be clinically identified or when echocardiography shows coronary sinus dilation. Vascular ultrasound or computed tomography may help identify jugular venous anomalies and should be considered in the preoperative evaluation of bulldogs that need to undergo interventional procedures requiring transjugular catheterization.

Abstract

Two French bulldogs and one English bulldog affected by pulmonary valve stenosis and referred for pulmonary balloon valvuloplasty were diagnosed with different abnormalities of the external jugular veins. The diagnosis included unilateral absence of the right external jugular vein and bilateral hypoplasia of the external jugular veins, associated with persistent left cranial vena cava. Vascular ultrasound and computed tomography were used for the diagnosis. Jugular vein anomalies can affect decision-making regarding the central venous catheterization needed to perform procedures such as pulmonary balloon valvuloplasty or central catheter placement. Based on the results of the present case series, anomalies of external jugular veins should be considered in French and English bulldogs when the external jugular veins cannot be palpated or when echocardiography shows coronary sinus dilation. Vascular ultrasound or computed tomography may help identify jugular venous anomalies and should be considered in the preoperative evaluation of bulldogs that need to undergo interventional procedures requiring transjugular catheterization.

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.

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.

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.

Evaluation of the NuCLEUS-X™ balloon valvuloplasty catheter for severe pulmonic stenosis in dogs

INTRODUCTION/OBJECTIVES

Balloon instability is commonly encountered during balloon pulmonary valvuloplasty (BPV) and may result in an unsuccessful procedure. The NuCLEUS-X™ catheter is a recently developed BPV catheter with a unique barbell shape and an ordered pattern of inflation that stabilizes the balloon to span the valve annulus before expansion of the balloon center.

ANIMALS

Ten client-owned dogs with severe valvular pulmonic stenosis (PS).

MATERIALS AND METHODS

Prospective observational study. The BPV procedure was performed by standard technique with use of NuCLEUS-X™ catheters targeting a balloon-to-annulus ratio between 1.2 and 1.5. Balloon stability, safety, and procedural success were assessed. Procedural success was defined as either a reduction in the Doppler transpulmonic PG by at least 50% of the pre-procedural PG or <80 mmHg one month post procedure.

RESULTS

Balloon stability centered at the pulmonic valve on the first inflation was achieved in 10/10 cases. The mean PG before BPV was 141 mmHg ±41 mmHg, and the PG after BPV at one month was 83 mmHg ±41 mmHg. Procedural success was achieved in 56% of patients. All dogs survived the BPV, and no major procedural complications were encountered using the NuCLEUS-X™ catheter.

CONCLUSIONS

The use of the NuCLEUS-X™ catheter is feasible for BPV in dogs with severe PS. The unique balloon shape provided catheter stability on the first inflation in all dogs, which may be beneficial when stabilization of a conventional BPV catheter cannot be achieved.

Cardiac Interventions in Small Animals: Areas of Uncertainty

There remain areas of uncertainty in optimal technique, preferred candidates, and expected outcome for small animal patients undergoing cardiac intervention. This article highlights issues within interventional cardiology that are in need of study and offers the author's opinion and experience on topics such as variants of pulmonary valve anatomy and alternatives to conventional balloon dilation for pulmonary valve stenosis, patient selection for cutting or high-pressure balloon dilation of aortic valvar or subaortic stenosis, occlusion of patent ductus arteriosus in very small dogs, ductal stenting in conditions with reduced pulmonary blood flow, and alternative considerations for vascular access and closure.

Successful surgical correction of supravalvular pulmonary stenosis under beating heart using a cardiopulmonary bypass system in a dog

A male Pomeranian dog aged 1 year and 8 months was presented for evaluation of severe systolic ejection, cardiac murmur and syncope on excitation. Supravalvular pulmonary stenosis was diagnosed. An echocardiogram showed a supravalvular membranous stricture and a severely increased pulmonary arterial velocity in the stricture (6.49 m/s, pressure gradient of 169 mmHg). The supravalvular stricture was surgically removed by pulmonary arteriotomy with the heart beating using a cardiopulmonary bypass system. The postoperative pulmonary arterial velocity at the narrow area decreased to 3.80 m/s, and the pressure gradient decreased to 57.7 mmHg. Six months after the operation, there were no signs of restenosis, and the dog was in good condition without syncope. Surgical correction of pulmonary stenosis with the heart beating using a cardiopulmonary bypass system is useful because of the improvement it brings in safety and reliability.