Transcatheter closure of patent ductus arteriosus in 11 dogs and one cat after incomplete or aborted surgical ligation

ObjectiveTo describe the characteristics and outcomes of transcatheter patent ductus arteriosus (PDA) occlusion after incomplete or aborted surgical ligation in dogs and cats.AnimalsTwelve client-owned animals (11 dogs and one cat).Materials and methodsThis retrospective study describes data from animals with aborted or incomplete surgical PDA ligation that subsequently underwent transcatheter closure using endovascular methods. Patient demographics, reason for incomplete or aborted surgery, complications, and method of transcatheter occlusion were recorded. Data are presented as mean ± standard deviation or median (interquartile range), where appropriate.ResultsFor all cases, median age at surgery was 12.2 months (4.9–15.1 months) and at catheterization was 15.4 months (8.9–21.9 months), with 79 days (29–209 days) between surgical and interventional procedures. Median weight at catheterization was 4.5 kg (2.5–12.6 kg). Reasons for failed surgical ligation included hemorrhage during ductal dissection in seven dogs, residual flow in four dogs, and inability to identify the ductus in one cat. Transcatheter closure was successfully performed using a canine duct occluder in eight dogs, transarterial coil embolization in two dogs, and transvenous coil embolization in one dog and one cat. Metallic hemoclips partially obscured angiographic findings in three cases with prior surgical hemorrhage but did not prevent transcatheter closure. In all cases, ductal flow was successfully attenuated, with no or trace residual shunting on angiography and complete occlusion the following day on echocardiography.ConclusionsWhen surgery is unsuccessful, either owing to hemorrhage or residual flow, transcatheter closure of PDA is feasible, even in small patients.     

Use of a self-expanding occluding stent for nonsurgical closure of patent ductus arteriosus in dogs

OBJECTIVE: To evaluate the clinical application of a catheter-delivered, self-expanding occluding stent for closure of patent ductus arteriosus (PDA) in dogs. DESIGN: Prospective study. ANIMALS: 23 client-owned dogs weighing at least 3 kg (6.6 lb). PROCEDURE: Dogs were evaluated by physical examination, electrocardiography, thoracic radiography, and 2-dimensional, M-mode, spectral and color-flow Doppler echocardiography to confirm the diagnosis and obtain baseline measures. Shunt severity and ductal size and anatomy were established by means of angiography. With fluoroscopic guidance, the occluding stent, attached to a delivery cable, was maneuvered though the right side of the heart into the ductus via a prepositioned introducer sheath. After angiographic verification of appropriate stent placement, the delivery cable was detached, and the introducer sheath was withdrawn. Closure of the PDA was evaluated by means of angiography 15 minutes after stent deployment and by echocardiography 1 and 3 months after the procedure. RESULTS: There were no operative deaths. There were 2 deployment failures, both attributable to avoidable operator errors. Angiography performed after stent deployment indicated PDA closure in 13 of 20 (65%) dogs. There were 2 postoperative deaths in dogs with heart failure; both deaths were thought to be unrelated to use of the occluding stent. Complete PDA closure, determined by Doppler color-flow echocardiography, was evident in 17 of 19 dogs within 3 months and in 1 additional dog within 1 year of stent deployment, resulting in closure in 18 of 19 dogs completing the study protocol. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that a catheter-delivered occluding stent can be used successfully to close PDAs in dogs.     

Acute onset of pulmonary necrotising arteritis in a dog with a left-to-right patent ductus arteriosus

A 12-week-old, clinically normal Chihuahua was referred for investigation for a continuous heart murmur. Cardiac evaluation revealed an anatomically and haemodynamically typical left-to-right shunting patent ductus arteriosus. The continuous wave Doppler measurement of peak ductal jet velocity of 5.6 m/s was suggestive of a normal pulmonary to systemic arterial pressure ratio. The dog returned 16 days later with right heart failure and severe pulmonary hypertension. Marked reduction in left-to-right shunting was demonstrated and the ductal jet velocity had decreased to 2.5 m/s. Immediate ductus ligation, oxygen therapy before and after the operation, and administration of hydralazine failed to reduce pulmonary hypertension, and the dog was euthanased. Histopathological examination of the lung showed pulmonary necrotising arteritis with acute and chronic arterial lesions. Chronic pulmonary vascular changes related to high flow have been associated with altered nitric oxide and endothelin responses. These changes may be responsible for the acute onset of pulmonary hypertension due to relatively minor vascular insults in some human and veterinary patients with left-to-right shunts. The potential for acute progression supports the recommendations for early ductus ligation and the prognostic importance of detecting pulmonary hypertension presurgically in patent ductus arteriosus patients.     

Medial insertion of the patent ductus arteriosus characterized by computed tomography angiography in a cat and dog

Surgical ligation of a left-to-right shunting patent ductus arteriosus was attempted in two animals. In both cases, a young cat and dog, ligation was complicated by poor visualization of the ductus resulting in unsuccessful ligation. Post-operatively, both the cat and dog underwent computed tomography angiography to characterize the location and morphology of the patent ductus arteriosus. In both cases, computed tomography angiography revealed a left-to-right shunting patent ductus arteriosus with an insertion location medial to the left pulmonary artery branch compared to the typical location. We hypothesize that this atypical location resulted in a difficult surgical visualization from the left thoracotomy approach. Transvenous coil embolization of the duct from the external jugular vein was performed in both cases and resulted in successful occlusion. Variations in the medial-lateral insertion of the ductus arteriosus may have consequences for surgical intervention. If an atypical location of a patent ductus arteriosus is suspected on transthoracic echocardiography, computed tomography angiography prior to ligation may be useful to further define ductal location and help guide the surgical approach.     

Intracardiac echocardiography: use during transcatheter device closure of a patent ductus arteriosus in a dog

Intracardiac echocardiography (ICE) is used in humans for percutaneous interventional procedures, such as transcatheter device closures. Intracardiac echocardiography provides high-resolution imaging of cardiac structures with two-dimensional, M-mode, Doppler, and also three-dimensional modalities. The present report describes application of ICE during transcatheter occlusion of patent ductus arteriosus using a canine ductal occluder in a dog for which transesophageal echocardiography could not provide an optimal acoustic window.     

Transcatheter embolisation of patent ductus arteriosus using an Amplatzer vascular plug in six dogs

OBJECTIVES: The objective of this study was to assess the feasibility of transcatheter embolisation of a patent ductus arteriosus using an Amplatzer vascular plug (Amplatzer Medical UK) in six dogs. METHODS: The Amplatzer vascular plug is a self-expandable, cylindrical device attached to a delivery cable. In all the dogs, the device was delivered transvenously. Successful device implantation was defined as firm anchorage of the device squarely within the distal part of the ductus arteriosus with no intra- or postoperative dislodgement. Successful occlusion of the ductus arteriosus occurred if a disappearance of the continuous murmur was achieved 24 hours after placement of the Amplatzer vascular plug. RESULTS: The age of the dogs ranged from 16 weeks to 7.5 years. Their weights ranged from 2.9 to 27.6 kg (median 6 kg). Two dogs had congestive heart failure before embolisation. Successful device implantation was achieved in all dogs. Successful occlusion of the ductus arteriosus was achieved in four of the six dogs. Complications included mild lameness, residual shunting, and bruising and pruritus around the surgical wound site. At follow-up, two dogs had a continuous murmur and one required treatment for congestive heart failure. CLINICAL SIGNIFICANCE: This technique may represent a clinically effective and less expensive alternative to the use of an Amplatzer duct occluder (Amplatzer Medical UK) in dogs with medium-sized patent ductus arteriosus. Further investigations are required to fully evaluate its efficacy and safety in various sizes and types of patent ductus arteriosus, and to determine the optimal device size in relation to the size of the ductus.     

Pulmonary embolization of vascular occlusion coils in dogs with patent ductus arteriosus

Transcatheter coil embolization of patent ductus arteriosus (PDA) was performed in 206 dogs between 1994 and 2003 at Texas A&M University, of which 7 (3%) had embolization of coils to the pulmonary vasculature. Thoracic radiographs indicated that coils were located in the right pulmonary artery in 6 of the 7 dogs. Pulmonary perfusion scans were available for review in 5 dogs, and moderate perfusion defects were observed in the right caudal lung lobe in 4 dogs within 24 hours of embolization. Perfusion deficits observed initially in 2 of the dogs resolved on perfusion scans performed at 6 months and 3.1 years. One dog did not have evidence of focal perfusion defects on a perfusion scan performed 4.5 months after embolization. All pulmonary embolizations occurred during the procedure. Attempts at retrieval of coils were unsuccessful in the 2 dogs in which it was attempted. No short- or long-term clinical complications were observed in any of the dogs with pulmonary embolization. We conclude that pulmonary embolization of vascular occlusion coils is an uncommon event and is not typically associated with adverse clinical effects in dogs with PDA.     

Transvenous embolization of small patent ductus arteriosus with single detachable coils in dogs

Transvenous embolization of small patent ductus arteriosus (PDA; < or = 4 mm) with a single detachable coil was attempted in 24 dogs (median age 5.7 months, range, 2.6-65.5 months; median body weight 5.5 kg, range, 1.5-30.0 kg). Angiographic imaging of the duct and pressure measurements were made before and after embolization. The minimal ductal diameter was 2.7 +/- 0.7 mm. In all dogs, a single coil was employed regardless of residual shunting. Ten dogs (PDA minimal diameter range, 1.5-2.2 mm) received a 5-mm coil, and 14 dogs (PDA minimal diameter range, 2.9-3.6 mm) received a 8-mm coil. After coil embolization the angiographic shunt grade decreased significantly (n = 20, P < .001). Residual shunts were assessed by angiography 15 minutes after and by Doppler echocardiography 1-3 days and 3 months after the intervention. In the dogs treated with the 5-mm coils the residual shunt rate was low (0%, 10%, and 0% for angiography and Doppler echocardiography at 1-3 days and 3 months, respectively), in contrast to the dogs treated with the 8-mm coils (91%, 79%, and 67% for angiography and Doppler echocardiography at 1-3 days and 3 months, respectively). After 3 months, no residual murmur was found in dogs treated with the 5-mm coils (0/7), in contrast to murmurs in 5 of 12 (42%) dogs treated with the 8-mm coils. Despite incomplete closure in these dogs, volume loading of the left heart decreased in all dogs. Pulmonic or aortic coil embolism did not occur. Analysis of initial results shows that single detachable coil embolization is possible in all dogs with a small PDA (< or = 4 mm), but only very small PDA (< or = 2.5) could be treated effectively, and for the moderate PDA (2.6-4.0 mm) longer coils or multiple coils may be necessary to achieve complete occlusion.     

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.     

Use of transesophageal echocardiography for visualization of the patent ductus arteriosus during transcatheter coil embolization

Transesophageal echocardiography (TEE) enhances our ability to see the patent ductus arteriosus in the dog. The improved visualization may potentially improve our ability to perform transcatheter coil embolization in patients that are more likely to have a successful outcome. This report uses still and video images to detail the specifics of coil embolization as performed with the assistance of TEE and compares the images with those of angiography, surgery and postmortem examination.     

Treatment of patent ductus arteriosus by placement of two intravascular embolisation coils in a puppy

A 14-week-old border collie with a history of exercise intolerance was confirmed to have a patent ductus arteriosus (PDA) from colour flow Doppler echocardiography. Under general anaesthesia, angiography was performed to gauge accurately the width of the ductus, and then two intravascular embolisation coils were introduced into the ductus via percutaneous catheterisation of the femoral vein. The coils were both 8 mm in diameter, each with four loops. This led to an immediate disappearance of the murmur. Some slight residual flow was detected at the time of the procedure by angiography, but by 10 days postoperatively there was no PDA flow detectable. The time taken to complete the procedure was 55 minutes, with a total fluoroscopy time of 15 minutes. Placement of intravascular embolisation coils represents a viable alternative to traditional surgical methods of ductus closure.     

Perceptions of transcatheter device closure of patent ductus arteriosus in veterinary cardiology and evaluation of a canine model to simulate device placement: a preliminary study

Objectives

The purpose of this study was to evaluate a canine patent ductus arteriosus (PDA) model developed for practicing device placement and to determine practices and perceptions regarding transcatheter closure of PDA from the veterinary cardiology community.

Outcome clinical audit: analyses of interventional closure of patent ductus arteriosus in dogs

ObjectivesThe objectives of this study were to determine whether conducting a clinical audit was achievable in a group of centres that perform interventional cardiac procedures and to report the success and complications rates in dogs diagnosed with patent ductus arteriosus.MethodsThis was a multicentre, European-wide, prospective study. Patient data were entered into a bespoke database prior to commencing interventional closure of patent ductus arteriosus in all animals undergoing this procedure during the study period. The database was designed to gather clinical audit information, after completion of the procedure, such as discharge outcome, complication rate, and medium-term outcome.ResultsA total of 339 cases were included from five participating centres. The process of performing clinical audit was achieved in all centres. Successful discharge outcome was 95.9% with a complication rate of 4.1%. The procedure-related mortality was 0.6%. 149 cases (43.9%) were either lost to follow-up or had not yet had a follow-up within the time period. Of the remaining 169 cases in which follow-up was available, 157 (92.9%) cases had a successful medium-term outcomeConclusionsThis study demonstrates that the process of performing a clinical audit is achievable in veterinary clinical interventions across different centres. These results provide a benchmark for future comparison in our ongoing clinical audit and validate the process of clinical audit for other centres performing cardiac interventions. The use of clinical audit should be considered in other aspects of veterinary medicine.     

Etiology of patent ductus arteriosus in dogs

Patent ductus arteriosus (PDA) is the most common congenital heart disease in dogs and usually causes heart failure and death unless corrected at a young age. Previous histologic studies in a line of dogs derived from Miniature Poodles with hereditary PDA identified varying degrees of hypoplasia and asymmetry of ductus-specific smooth muscle and the presence of aortalike elastic tissue in the ductus wall sufficient to cause patency. To determine if similar structural abnormalities cause PDA in other dogs, serial-section, 3-dimensional histology of ductal architecture was studied in 8 non-Poodle purebred dogs with PDA with no immediate family history of PDA. Morphologic abnormalities were observed in 7 of 8 dogs with PDA and essentially were the same as those in dogs known to have a hereditary form of PDA. These findings suggest that apparently sporadic PDA in these breeds is caused by a genetic defect in the structure of the ductus arteriosus that is similar or identical to that in the Poodle. The relatives of dogs with PDA, particularly parents, offspring, and siblings, should be screened for evidence of PDA. Dogs with PDA should not be used for breeding, regardless of breed.     

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.     

Real-time 3D transesophageal echocardiography-guided closure of a complicated patent ductus arteriosus in a dog

Advanced imaging modalities are becoming more widely available in veterinary cardiology, including the use of transesophageal echocardiography (TEE) during occlusion of patent ductus arteriosus (PDA) in dogs. The dog in this report had a complex history of attempted ligation and a large PDA that initially precluded device placement thereby limiting the options for PDA closure. Following a second thoracotomy and partial ligation, the morphology of the PDA was altered and device occlusion was an option. Angiographic assessment of the PDA was limited by the presence of hemoclips, and the direction of ductal flow related to the change in anatomy following ligature placement. Intra-operative TEE, in particular real-time three-dimensional imaging, was pivotal for assessing the PDA morphology, monitoring during the procedure, selecting the device size, and confirming device placement. The TEE images increased operator confidence that the size and location of the device were appropriate before release despite the unusual position. This report highlights the benefit of intra-operative TEE, in particular real-time three-dimensional imaging, for successful PDA occlusion in a complicated case.