Patent ductus arteriosus occlusion in small dogs utilizing a low profile Amplatz® canine duct occluder prototype

Transvenous embolization of moderate to large patent ductus arteriosus in dogs using the Amplatzer vascular plug II

BACKGROUND

Catheter-based occlusion of patent ductus arteriosus (PDA) can be performed using different devices. Transvenous embolization using the Amplatzer vascular plug II (AVP-II) has been studied in humans, but it has not been described in dogs.

OBJECTIVE

Evaluate the feasibility and success of transvenous embolization of PDA using the AVP-II in dogs.

ANIMALS

Nineteen client-owned dogs with left-to-right shunting PDA, with minimal ductal diameter >2.5 mm.

METHODS

Prospective observational study using AVP-II with transvenous access for PDA closure in dogs.

RESULTS

Angiography showed a conical ductus with a long (n = 17) or short (n = 2) ampulla. The minimal diameter of the duct was 4.34 ± 1.11 mm, and the maximal diameter of the ampulla was 13.18 ± 3.47 mm. Technical success was achieved in 18 of the 19 (94.7%) patients after the first intervention and in all 19 (100%) patients after the second intervention. Postrelease angiography documented complete occlusion of the PDA in 10 of 19 (52.6%) dogs. Mild flow acceleration or stenosis of the left pulmonary artery was found in 6 and 1 of the 17 analyzed cases, respectively, by Doppler examination. The closure rate 24 hours after intervention was 94.7% (18/19). The remaining dog had a moderate residual shunt, and delayed complete closure after 3 months led to a 100% closure rate.

CONCLUSION AND CLINICAL IMPORTANCE

The AVP-II is a safe and effective device for transvenous embolization in dogs with moderate to large PDA.

Pre-procedural femoral vessel ultrasound in dogs with patent ductus arteriosus: diameter, image quality and relationship with arterial catheterization

INTRODUCTION

/Objectives: Patent ductus arteriosus (PDA) in dogs is often treated via minimally invasive transvascular occlusion using femoral artery access. This study compared ultrasound-derived diameter and image quality of the right femoral artery (RFA) and vein (RFV) in dogs with PDA using a linear ultrasound probe (L-P) and phased-array transthoracic echocardiography probe (TTE-P). The case outcome was assessed.

ANIMALS, MATERIALS & METHODS

Forty-five client-owned dogs with PDA were prospectively enrolled. Ultrasound-measured RFA and RFV diameters were obtained on images acquired with both probes pre-operatively and compared using Bland-Altman plots. The image quality of RFA and RFV was scored on L-P and TTE-P images.

RESULTS

Comparison of RFA and RFV diameter from L-P versus TTE-P images revealed: [Mean difference (limits of agreement): RFA = 0.009 mm (-0.78-0.79 mm), RFV = 0.523 mm (-1.75-2.79 mm)]. Image quality scores were significantly higher for L-P than TTE-P (P < 0.0001). In six small dogs, measurable images were unattainable with TTE-P. Dogs of similar body weight had variable RFA diameters. Twenty-seven dogs had RFA catheterization. In 21/27 dogs, RFA diameter exceeded the external diameter of the introducer used for catheterization, and in 6/27, it was smaller.

CONCLUSIONS

Pre-procedural ultrasound of the RFA in dogs with PDA is useful given variable RFA diameter relative to body weight. Despite poorer image quality, RFA diameters from TTE-P images were very similar to L-P images on average, suggesting TTE-Ps are suitable for pre-procedural planning in most dogs. Vasospasm, hypotension or differences in the location of ultrasound measurement versus catheterization might produce variation in pre-procedural versus intraoperative RFA size.

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.

Late recanalization after complete occlusion of patent ductus arteriosus in a Pembroke Welsh Corgi with von Willebrand disease

A 36‐month‐old female Pembroke Welsh Corgi with a cardiac murmur weighing 12.6 kg was referred to the Matsubara Animal Hospital cardiology service. Echocardiography revealed a patent ductus arteriosus. The dog underwent ductus arteriosus closure using an Amplatz Canine Duct Occluder. After the operation, we suspected coagulation and a platelet disorder because of the slightly increased haemorrhage during the operation, postoperative purpura around the surgical wound inside of the thigh, and dog breed, which is known to be commonly affected with von Willebrand disease (vWD). Subsequently, type 1 vWD was confirmed. Complete occlusion was achieved 1 month after the operation; however, 2 months after the operation, recanalization appeared. Recanalization progressed gradually; cardiac redilation was not detected 6 years after the operation. The late recanalization was most likely associated with vWD. In canine breeds pre‐disposed to developing vWD, pre‐operative testing may be indicated prior to patent ductus arteriosus occlusion, though the prevalence of vWD is rare.

Low profile vascular plug for transarterial occlusion of patent ductus arteriosus in small dogs

Background

Minimally invasive transcatheter occlusion using Amplatz canine duct occluder (ACDO) is the treatment of choice for dogs with left‐to‐right shunting patent ductus arteriosus (PDA). However, in small dogs the femoral artery diameter is often too small to accommodate the guiding catheter required for ACDO deployment.

Objective

Describe the effectiveness of transarterial implantation of Amplatzer Vascular Plug 4 (AVP‐4), the only self‐expandable nitinol mesh occlusion device which can be implanted through a 4 French diagnostic catheter, in small dogs with left‐to‐right shunting PDA.

Animals

Seven client‐owned dogs.

Methods

Descriptive case series. Dogs with hemodynamically relevant left‐to‐right shunting PDA and a femoral artery diameter less than 2.0 mm measured preoperatively with ultrasonography were prospectively enrolled.

Results

Angiography after releasing the device showed complete immediate PDA closure in 5 dogs, where the manufacturers' recommendation were strictly followed (30%‐50% device oversizing of the ductal ampulla's diameter). Trivial residual flow on angiography in the 6th dog, whose device was slightly undersized, had resolved on echocardiography within 2 hours after placement. Marked device undersizing in the 7th dog resulted in severe residual shunting, which necessitated the addition of a coil. In this dog, the AVP‐4 embolized into the pulmonary artery within 2 weeks after placement.

Conclusions and Clinical Importance

Transarterial implantation of AVP‐4 is a safe, effective and technically easy procedure for PDA occlusion in small dogs and offers a valuable alternative to coil implantation. Accurate PDA measurement and device sizing is essential to prevent residual shunting, inadvertent device embolization, and protrusion of the device into the aorta.

An experimental canine patent ductus arteriosus occlusion device based on shape memory polymer foam in a nitinol cage

Patent ductus arteriosus (PDA) is a congenital cardiovascular defect in which a fetal connection between the aorta and pulmonary artery does not spontaneously close shortly after birth. If left uncorrected serious complications and even death can occur. Surgical ligation is the traditional treatment method; however, it is an invasive procedure, that motivates development of a minimally invasive option. Shape memory polymer (SMP) foams are unique materials that hold promise in the field of minimally invasive occlusion devices. In this work, a prototype nitinol foam cage (NFC) incorporating SMP foams has been designed and evaluated in multiple mechanical and in vitro verification tests. The NFC demonstrated acceptable fatigue resistance in a preliminary strut integrity test, withstanding one million cycles without complete strut fracture. Radial force analysis of both thick- and thin-walled prototype variations generated less vessel distension and wall tension in a vessel mimic compared to a commercial device. The NFCs exhibited negligible in vitro migration, comparable to that of a commercial device, using simplified, ideal models of PDA. Deployment characteristics of the prototypes were evaluated and compared to that of a commercial device when delivered into physiological models of PDA. During mock deployments, a veterinary cardiologist noted that, while deliverable, the thin-walled NFC prototype exhibited poor deployment characteristics, however the thick-walled NFC had deployment characteristics comparable to that of a commercial device. The promising results of this study warrant further investigation of the NFC device for canine PDA closure.