Transvenous Embolization of Small Patent Ductus Arteriosus with Single Detachable Coils in Dogs

Two- and three-dimensional transesophageal echocardiographic assessment and successful occlusion of a window-like patent ductus arteriosus in two dogs

A 16-month-old Labrador-poodle cross (case 1) and a 3-month-old German shorthaired pointer (case 2) were referred for patent ductus arteriosus (PDA) occlusion. Two-dimensional transthoracic and two- and three-dimensional transesophageal echocardiography revealed a window-like PDA characterized by a wide and short ductus. Due to the atypical PDA morphology with no ampulla in case 1, ductal occlusion was attempted with non-canine-specific Amplatzer occluder devices. However, these were too small and failed to remain stable. Amplatz Canine Duct Occluder (ACDO) devices were used with success in both cases. Due to the defects' morphology, the proximal ACDO disc protruded into the aorta but there were no signs of obstruction to aortic blood flow 16 months (case 1) and 1 month (case 2) post-occlusion. We describe two cases of a window-like type PDA that were successfully occluded with an ACDO.

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.

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.

Transjugular patent ductus arteriosus occlusion in a cat with a peripheral vascular occlusion device

A five-month-old, intact female domestic shorthair cat was presented to a specialty referral hospital for evaluation of a patent ductus arteriosus. Transvenous embolization of the defect was achieved with a commercially available peripheral vascular plug. The use of vascular plugs for the closure of patent ductus arteriosus has been validated in dogs, yet literature for its use in cats is lacking. The product and procedural details of the device are described.

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.

Differences in human and sheep platelet adherence, aggregation and activation induced by glass beads in a modified chandler loop-system

In human cardiovascular research, sheep in particular are used as a large animal model in addition to pigs. In these animals, medical products, developed and tested for human medical purposes, are almost exclusively used in interventional studies. Therefore, the extent to which platelets from human and ovine blood differ in terms of adherence, aggregation and activation after a 4- or 8-minutes exposure to glass was investigated. Testing was performed with platelet-rich plasma (PRP) and a modified chandler loop-system, with 4- and 8-minute blood-material exposure times corresponding to 20 and 40 test cycles, respectively, through the entire silicone tube loop of the test system.In sheep and human PRP, contact with the silicone tubing resulted in a decrease in platelet count after 4 minutes and 20 test cycles, respectively. Four more minutes (20 additional test cycles) caused a further decrease of the platelet count only in sheep PRP. When the silicon tube was partly filled with glass beads, these effects were more pronounced and stronger in sheep then in human PRP.The mean platelet volume, which was used as parameter for platelet aggregation, did not change over time in human PRP without glass exposure. With glass exposure in human and sheep PRP the mean platelet volume increased within 40 test cycles, but this increase was stronger in sheep than in human PRP.Regarding activation behavior, the activation markers CD62P and CD63 were detectable only in < 30% (sheep) and < 45% (human) of platelets, whereas after 8 min of glass exposure, the proportion of CD62P+ and CD63+ cells was more increased than before only in sheep. These results indicate that ovine platelets adhere more strongly to glass and show stronger aggregation behavior after glass contact than human platelets, but that ovine and human platelets differ only slightly in activability by glass.

Transarterial correction of patent ductus arteriosus in small dogs with the Amplatz™ Vascular Plug 4: A pilot study

OBJECTIVES

Determine if the Amplatz™ Vascular Plug 4 (AVP4) can be used to occlude left-to-right shunting patent ductus arteriosus (PDA) in dogs with inadequate arterial vascular access for the Amplatz Canine Duct Occluder (ACDO).

ANIMALS

Six adolescent dogs with PDA whose femoral artery was too small for insertion of a 4 Fr vascular access sheath.

MATERIALS AND METHODS

Standard femoral arterial vascular access and a 4 Fr diagnostic catheter were used to deploy an appropriately sized AVP4 into the PDA of each dog. Successful occlusion was defined as no residual ductal flow and determined by color Doppler echocardiography and angiography.

RESULTS

The AVP4 was successfully deployed, and complete occlusion of the PDA was achieved in all dogs. There were no complications encountered in any of the dogs.

CONCLUSIONS

The AVP4 is a viable option for the correction of PDA in dogs with inadequate arterial vascular access for the ACDO and should be considered as one of the options available for PDA correction in this challenging animal population.

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.

Alternative methods for the measurement of the minimal ductal diameter of a patent ductus arteriosus in a dog

A two and half-year-old, 24 kg, spayed female German Shepherd was presented for evaluation of a suspected patent ductus arteriosus (PDA). Transthoracic echocardiographic examination confirmed a left to right shunting PDA. Closure of the PDA was recommended, and the owners elected to have minimally invasive transcatheter closure of the PDA performed. Standard ductal angiography failed to provide adequate measurements of the minimal ductal diameter (MDD). Alternative methods of measuring the MDD using an angiography catheter and a balloon catheter were performed. The PDA was occluded using an Amplatz^® Canine Ductal Occluder without complication. Further evaluation of these techniques is needed to determine the accuracy, overall clinical efficacy, and safety of using alternative methods for the measurement of the MDD of a PDA.

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

OBJECTIVES

To develop procedural methodology and assess the safety, utility and effectiveness of a low profile Amplatz(®) canine duct occluder (ACDO) prototype in dogs deemed too small to undergo ductal occlusion with the commercially-available ACDO device.

ANIMALS

Twenty-one dogs with left-to-right shunting patent ductus arteriosus (PDA). Dogs were ≥1.5 kg but considered too small to accommodate a 6 Fr catheter or 4 Fr sheath within the femoral artery.

METHODS

Prospective canine study using a low profile ACDO prototype delivered through a 4 Fr catheter via a femoral arterial approach. Procedural methods, fluoroscopy time, perioperative complications, and residual ductal flow were evaluated, and angiographic ductal morphology and dimensions were tabulated.

RESULTS

All 21 dogs underwent successful ductal occlusion using the prototype device, 4 Fr catheter, and right femoral artery approach. No perioperative complications or device embolization occurred. The median minimal ductal diameter was 1.9 mm (range, 0.4-3.4), and the median device size deployed was 4 mm (range, 3-6). Complete ductal occlusion was noted in 17 dogs (81%) on post-deployment angiography. Twenty dogs (95%) had no residual flow on echocardiography performed the following day. In the 17 dogs (81%) that returned for a long-term (≥3months) follow-up evaluation, all had complete ductal occlusion based on echocardiography.

CONCLUSIONS

The low profile ACDO prototype is a safe and effective method of PDA occlusion in the small dog. The deployment procedure appears of similar technical difficulty to the commercially available ACDO.

Multidetector-row computed tomography of thoracic aortic anomalies in dogs and cats: patent ductus arteriosus and vascular rings

BACKGROUND

Diagnosis of extracardiac intrathoracic vascular anomalies is of clinical importance, but remains challenging. Traditional imaging modalities, such as radiography, echocardiography, and angiography, are inherently limited by the difficulties of a 2-dimensional approach to a 3-dimensional object. We postulated that accurate characterization of malformations of the aorta would benefit from 3-dimensional assessment. Therefore, multidetector-row computed tomography (MDCT) was chosen as a 3-dimensional, new, and noninvasive imaging technique. The purpose of this study was to evaluate patients with 2 common diseases of the intrathoracic aorta, either patent ductus arteriosus or vascular ring anomaly, by contrast-enhanced 64-row computed tomography.

RESULTS

Electrocardiography (ECG)-gated and thoracic nongated MDCT images were reviewed in identified cases of either a patent ductus arteriosus or vascular ring anomaly. Ductal size and morphology were determined in 6 dogs that underwent ECG-gated MDCT. Vascular ring anomalies were characterized in 7 dogs and 3 cats by ECG-gated MDCT or by a nongated thoracic standard protocol. Cardiac ECG-gated MDCT clearly displayed the morphology, length, and caliber of the patent ductus arteriosus in 6 affected dogs. Persistent right aortic arch was identified in 10 animals, 8 of which showed a coexisting aberrant left subclavian artery. A mild dilation of the proximal portion of the aberrant subclavian artery near its origin of the aorta was present in 4 dogs, and a diverticulum analogous to the human Kommerell's diverticulum was present in 2 cats.

CONCLUSIONS

Contrast-enhanced MDCT imaging of thoracic anomalies gives valuable information about the exact aortic arch configuration. Furthermore, MDCT was able to characterize the vascular branching patterns in dogs and cats with a persistent right aortic arch and the morphology and size of the patent ductus arteriosus in affected dogs. This additional information can be of help with regard to improved diagnoses of thoracic anomalies and the planning of surgical interventions.

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.

Transthoracic echocardiographic guidance of patent ductus arteriosus occlusion with an Amplatz® canine duct occluder

Placement of an Amplatz canine duct occluder (ACDO) is usually performed by fluoroscopy (Nguyenba and Tobias, 2007). The latter technical approach presents limitations, mostly due to radiation exposure, making this practice dangerous for the patient and operators. In this study, we describe the successful placement of an Amplatz Canine Duct Occluder device by using transthoracic echocardiographic (TTE) guidance, performed on an 11-month-old female mongrel dog with a grade VI/VI continuous heart murmur diagnosed with patent ductus arteriosus (PDA). The TTE is useful in eliminating exposure to radiation and is more versatile than fluoroscopy in conveying real-time detailed information concerning the position of the ACDO.

The Amplatz canine duct occluder: a novel device for patent ductus arteriosus occlusion

The Amplatz canine duct occluder (ACDO) is a nitinol mesh device with a short waist that separates a flat distal disc from a cupped proximal disc. The device is designed to conform to the morphology of the canine patent ductus arteriosus (PDA). PDA dimensions are determined by angiography, and a guiding catheter is advanced into the main pulmonary artery via the aorta and PDA. An ACDO with a waist diameter approximately twice the angiographic minimal ductal diameter (MDD) is advanced via the catheter using an attached delivery cable until the flat distal disc deploys within the main pulmonary artery. The partially deployed ACDO, guiding catheter, and delivery cable are retracted until the distal disc engages the pulmonic ostium of the PDA. With the delivery cable stabilized, the catheter is retracted to deploy the waist across the pulmonic ostium and cupped proximal disc within the ductal ampulla. Tension on the delivery cable is released, and correct ACDO positioning and stability are confirmed by observing that the device assumes its native shape, back-and-forth maneuvering of the delivery cable, and a small contrast injection made through the guiding catheter. The delivery cable is detached and removed with the guiding catheter. To assess for any residual ductal flow, an angiogram is performed at the conclusion of the procedure, followed by Doppler echocardiography at 1 day and 3 months post-procedure. PDA occlusion in dogs with the ACDO is straightforward and extremely effective across a wide range of body weights, somatotypes, MDDs, and ductal morphologies.

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.

Transcatheter closure of patent ductus arteriosus in a dog with a peripheral vascular occlusion device

A 4-month-old, intact female mixed-breed dog presented to the Purdue University Veterinary Teaching Hospital for evaluation of a cardiac murmur. A large left-to-right patent ductus arteriosus (PDA) was diagnosed and interventional correction was achieved with a commercially available peripheral vascular occlusion device (VOD). The VOD is composed of a nitinol wire mesh and is similar in composition and shape to a commercially available human PDA occluder, however, it can be deployed through smaller delivery catheters and is much less expensive. The product and procedural details of the device are described.

Use of simultaneous fluoroscopic and echocardiographic guidance during transarterial coil placement for embolization of patent ductus arteriosus in dogs

OBJECTIVE

To evaluate the use of simultaneous fluoroscopic and transthoracic echocardiographic guidance during transarterial coil placement for embolization of patent ductus arteriosus (PDA) in dogs.

DESIGN

Descriptive report.

ANIMALS

3 dogs with PDA.

PROCEDURE

Each dog was anesthetized, and a femoral artery was exposed for vascular access. By use of an introducer, a catheter was placed in the thoracic portion of the descending aorta with fluoroscopic guidance, and subsequently, a bolus of iodinated radiographic contrast material was injected to outline the ductus. Under fluoroscopic guidance, 1 coil was positioned in the ductus, but not released. Transthoracic echocardiography was used to ensure that 1 loop of the coil was located in the pulmonary artery. When > 1 loop or no loops were detected in the pulmonary artery, the coil was retrieved and repositioned; when 1 loop of the coil was detected in the pulmonary artery, the coil was detached. After catheter removal, the femoral artery was ligated and the wound was closed.

RESULTS

In all 3 dogs, successful embolization of the PDA was achieved. Echocardiography prevented unintentional pulmonary artery embolization in 1 dog and suboptimal coil placement in the other 2 dogs.

CONCLUSIONS AND CLINICAL RELEVANCE

In addition to fluoroscopic control, transthoracic echocardiography appears to aid the appropriate positioning of a transarterial coil for treatment of PDA in dogs. Although transesophageal echocardiography would likely provide better images of the ductus, transthoracic echocardiography is a much cheaper, less specialized, and more widely available alternative.

Transarterial coil embolization for canine patent ductus arteriosus occlusion

Left to right shunting patent ductus arteriosus (PDA) is the most common canine congenital heart defect. If not occluded PDA is associated with high morbidity and mortality. Historically, surgical ligation has been the standard method of correction. Although highly successful, surgical ligation is associated with some operative morbidity and mortality. More recently, minimally invasive transcatheter techniques have been employed for PDA occlusion. Transarterial PDA coil embolization is a safe, cost effective, less invasive alternative offered by many specialty centers for PDA occlusion. This procedure involves catheterization of the femoral artery under general anesthesia. An angiogram is then performed to delineate PDA morphology and facilitate coil selection. Coils are commercially available and composed of surgical stainless steel with prothrombotic poly-Dacron fibers. Coils are advanced through a catheter into the PDA under fluoroscopic guidance until satisfactory angiographic occlusion is documented. Patients are then recovered and released the following day. This procedure requires substantial technical expertise and specialized equipment.

Long-term follow-up of dogs with patent ductus arteriosus

Postocclusion survival data from dogs with left-to-right shunting patent ductus arteriosus (PDA) was available from 80 dogs, diagnosed from 1990 to 2000. Of these, 37 had undergone a procedure to close the ductus and were re-evaluated at the time of this study; clinical data from the follow-up examination was compared with that from the original examination. Radiographically, the right ventricle remained apparently enlarged, and the aortic bulge associated with dilation of the descending aorta did not disappear after closure. On M-mode echocardiography, left ventricular chamber diameter in diastole and systole and left ventricular posterior wall in systole decreased significantly. Mitral endocardiosis was a common feature. Residual flow was evident in 46 per cent of the animals. Late closure occurred in 8 per cent of the dogs, and trivial recanalisation in 19 per cent. The maximum survival time postclosure was 168 months and, after non-occlusion, 114 months, suggesting that dogs with PDA follow an unpredictable course. However, there was a significant difference in survival times between the corrected and non-corrected group.

Sodium nitroprusside-induced deliberate hypotension to facilitate patent ductus arteriosus ligation in dogs

OBJECTIVE

To report the use of sodium nitroprusside to induce deliberate hypotension to reduce hemorrhage and facilitate surgical ligation of complicated patent ductus arteriosus (PDA) in dogs.

STUDY DESIGN

Retrospective study.

ANIMALS

Six dogs.

METHODS

Hemorrhage occurred during surgical ligation of PDA in 5 dogs. Surgical dissection and isolation of the PDA were very difficult in a sixth dog that was considered to be at increased risk for ductus rupture. Sodium nitroprusside (5 to 25 microg/kg/min intravenously) was administered to these 6 dogs to induce hypotension to reduce blood loss and facilitate surgical ligation of the PDA.

RESULTS

Sodium nitroprusside infusion reduced blood pressure (mean arterial pressure, 45 to 60 mm Hg) within 5 to 10 minutes and hemorrhage from the PDA, facilitating its surgical ligation. Recovery from surgery and anesthesia was uneventful in all 6 dogs.

CONCLUSIONS

Sodium nitroprusside infusion can be used to induce deliberate hypotension in dogs to facilitate surgical ligation of PDA.

CLINICAL RELEVANCE

Sodium nitroprusside infusion produces hypotension within 5 to 10 minutes and is easy to control, rapidly abates, and should help to facilitate surgical ligation of PDA.

Closure of large patent ductus arteriosus with a self-expanding duct occluder in two dogs

Of the different catheterisation methods described for closure of patent ductus arteriosus (PDA), coil embolisation is most commonly used in dogs. However, for a PDA larger than 4 to 5 mm in diameter, coil implantation is difficult. For these cases, the Amplatzer duct occluder (ADO) offers an alternative method. This report describes the successful implantation of an ADO in two dogs with large PDAs of approximately 6 mm diameter. The self-expandible device attached to an implantation wire was advanced through a long sheath antegrade to the femoral vein through the right heart and pulmonary artery to the duct and delivered into the PDA. Thereafter the device was released by unscrewing it from the delivery cable. The large PDA in both dogs was totally occluded by these means without any residual shunt. Thus, the ADO is a controlled release implant that also allows occlusion of a large PDA. Its high costs limit its general use in veterinary medicine at the present time.

Review of left-to-right shunting patent ductus arteriosus and short term outcome in 98 dogs

The case records of 98 dogs with a left-to-right shunting patent ductus arteriosus (PDA) were reviewed. There were 35 breeds represented, with a female to male ratio of 3:1. Forty per cent of the dogs were older than one year at initial presentation and 31 per cent had clinical signs attributable to PDA. A left heart base continuous murmur of grade IV/VI or higher was noted in 90 per cent of the dogs. On electrocardiography, the most common abnormalities were tall R waves (63 per cent) and deep QII waves (62 per cent). The radiographic triad of dilation of the descending aorta with enlargement of the main pulmonary artery segment and left atrium, typical of PDA, was noted in only 26 per cent of cases. Two-dimensional (2D) and M-mode echocardiography detected left atrial enlargement (35 per cent) and an increased left ventricular diameter in diastole (82 per cent) and systole (84 per cent) as the most common abnormalities. Doppler echocardiography demonstrated increased aortic outflow velocities in 66 per cent of cases. The overall short-term successful outcome in this study was 95 per cent. There was no significant difference between surgical ductal ligation using a standard technique or the Jackson-Henderson technique in terms of survival, occurrence of haemorrhage or residual shunting. The number of interventional procedures used in this study was too low for statistical comparison, but there appeared to be a trend towards a higher rate of residual shunting and a lower fatality rate using a coil occlusion technique.