Transarterial coil embolization for canine patent ductus arteriosus occlusion

Surgical treatment of a persistent right aortic arch with concurrent patent ductus arteriosus in a 4-month-old German shepherd dog

A 4-month-old intact female German shepherd dog was presented with a history of postprandial regurgitation, a palpably distended cervical oesophagus after eating, and poor weight gain despite a ravenous appetite. Computed tomography angiography, esophagoscopy and echocardiography identified a persistent right aortic arch with a concurrent patent ductus arteriosus (PDA) causing extraluminal oesophageal compression leading to marked segmental megaoesophagus. A heart murmur was not detectable. A left lateral thoracotomy was performed to ligate and transect the PDA without complication. The dog was discharged with mild aspiration pneumonia which resolved with antimicrobial therapy. Twelve months post-surgery the owners reported no regurgitation.

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.

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.

Mechanical and in vitro evaluation of an experimental canine patent ductus arteriosus occlusion device

Patent ductus arteriosus (PDA) is a congenital cardiovascular malformation in which a fetal connection between the aorta and pulmonary artery remains patent after birth. This defect commonly results in clinical complications, even death, necessitating closure. Surgical ligation is the most common treatment but requires a thoracotomy and is therefore invasive. A minimally invasive option is preferable. A prototype device for PDA occlusion which utilizes shape memory polymer foams has been developed and evaluated using mechanical and in vitro experiments. Removal force and radial pressure measurements show that the prototype device exhibited a lower removal force and radial pressure than a commercially available device. The in vitro experiments conducted within simplified and physiological PDA models showed that the prototype does not migrate out of position into the pulmonary artery at either physiological or elevated pressures in multiple model configurations. While the radial pressure and removal force were lower than commercial devices, the device performed acceptably in the in vitro benchtop experiments warranting further prototype development.

Goiter with vascular anomalies in a litter of Polish Lowland sheepdogs

At approximately 4-5 mo of age, three Polish Lowland sheepdog puppies from a single litter of eight puppies presented to their respective primary veterinarians with bilateral subcutaneous masses in their ventral cervical regions. Evaluation, including thyroid function testing, surgical exploration with resection, computed tomography, and angiography, identified the masses as enlarged thyroid glands with severely dilated and abnormal vasculature in the regions of the glands. The dogs were also found to have serum concentrations of thyroid hormones that were below the reference ranges. None of the three dogs showed clinical signs of hypothyroidism, except for the presence of goiter. One dog also had a patent ductus arteriosus that was surgically repaired. All dogs were clinically normal at 2 yr of age. This is the first report of major vascular anomalies associated with goiter in any species. The mechanism is unknown.

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.

Evaluation of the efficacy and safety of coil occlusion for patent ductus arteriosus in dogs

We performed a retrospective study of 56 dogs with Patent Ductus Arteriosus (PDA) to evaluate the indications for and efficacy of transarterial PDA coil embolization. Transarterial PDA coil embolization was conducted in 37 cases (66.1%) and surgical ligation was conducted in 16 cases (28.6%). Three cases (5.4%) were diagnosed as pulmonary hypertension and were excluded from surgical intervention. Although coil dislodgement was observed in the pulmonary artery in one case, no death occurred during coil embolization or surgical ligation. Echocardiography showed that fractional shortening decreased from 35.4 +/- 6.8% to 30.2 +/- 5.9% (P<0.05) after transarterial PDA coil embolization. Although slight residual shunts were observed in 18 cases, transarterial PDA coil embolization was effective treatment of PDA.

Retrieval of an embolization coil accidentally dislodged in the descending aorta of a dog with a patent ductus arteriosus

A 3.5-year-old intact female miniature poodle (weighing 2.7 kg) was referred to the Veterinary Teaching Hospital at Kangwon National University, because of inadvertent aortic embolization, by an occlusion coil used for the closure of patent ductus arteriosus (PDA). The coil was found at the site of the branching renal arteries in the abdominal aorta. A foreign body forceps with a three-wire nail tip was used, with fluoroscopic guidance, to retrieve the coil. After the removal, the dog was treated with heparin to prevent thromboembolization.

Retrospective Comparison of Surgical Ligation and Transarterial Catheter Occlusion for Treatment of Patent Ductus Arteriosus in Two Hundred and Four Dogs (1993?2003)

OBJECTIVE

To compare procedure time, complications, mortality, and short-term outcome in dogs with patent ductus arteriosus (PDA) treated by surgical ligation (SL) or transarterial coil occlusion (TCO).

STUDY DESIGN

Retrospective study.

ANIMALS

Dogs with PDA (n=204).

METHODS

Medical records of dogs treated for PDA were reviewed. Dogs treated by SL when it was the primary method used for PDA treatment (1993-1998) were compared with dogs treated by TCO when it was the primary method used for PDA treatment (1999-2003). Dogs treated during the transition between techniques, dogs treated with SL (1999-2003) and dogs treated with TCO before 1999, as well as dogs with pulmonary hypertension, or bidirectional or reversed (right-to-left) flow through the PDA were excluded from analysis.

RESULTS

Age, weight, gender distribution, and procedure times (P=.43) were similar for both groups. Major complications were more common with SL (12% versus 4.3%; P=.035) whereas minor complications were more common with TCO (12% versus 26%; P=.015). Initial success rate was higher for SL (94%) compared with TCO (84%; P=.027). There was no significant difference in mortality between SL (5.6%) and TCO (2.6%; P=.27).

CONCLUSIONS

Both SL and TCO are acceptable PDA treatments with comparable mortality; however, SL was associated with a higher risk of major complications and TCO was associated with a lower initial success rate.

Coil Occlusion of Residual Shunts After Surgical Closure of Patent Ductus Arteriosus

OBJECTIVE; To describe use of coil embolization to occlude residual flow through a patent ductus arteriosus (PDA) after incomplete surgical ligation.

STUDY DESIGN

Clinical study.

ANIMALS

Dogs (n=4) with continuous murmur after surgical ligation of PDA.

METHODS

After PDA ligation, residual ductal flow through the PDA was visible on color-flow Doppler examination and left ventricular end-diastolic diameter remained increased. Coil embolization by an arterial approach was performed to achieve complete occlusion of the PDA.

RESULTS

Embolization coils were delivered without complications and hemodynamically successful occlusion was achieved. Doppler-visible flow resolved in 2 dogs within 3 months after embolization. Left ventricular end-diastolic diameter indexed to body weight decreased in all dogs.

CONCLUSIONS

Transcatheter coil embolization appears to be a safe and minimally invasive procedure for complete occlusion of residual PDA flow after incomplete surgical ligation.

CLINICAL RELEVANCE

Transcatheter coil embolization should be considered for correction of hemodynamically significant residual shunts in dogs that have incomplete PDA occlusion after open surgical ligation.