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.     

Utility of Transesophageal Echocardiography for Transcatheter Occlusion of Patent Ductus Arteriosus in Dogs: Influence on the Decision‐Making Process

Background: Appropriate device selection for transcatheter occlusion of patent ductus arteriosus (PDA) is essential to procedural success. Objectives: To determine if transesophageal echocardiography (TEE) influences device selection for PDA occlusion and to report benefits, limitations, and complications associated with TEE. Animals: Twenty‐two client‐owned dogs with left‐to‐right shunting PDA. Methods: PDA dimensions were obtained via transthoracic echocardiography (TTE) and then TEE followed by angiography. Based solely on information from TTE and angiography, an initial device type and size were selected. After initial device selection, TEE measurements were disclosed and changes in device selection were recorded. After device release, angiography, TEE, or both were performed to assess occlusion. Results: An Amplatz canine duct occluder (ACDO) was securely positioned and released in 21 dogs and an embolization coil was deployed in 1 dog. Based on TEE evaluation, initial selected device type was unchanged but ACDO size was changed in 3 dogs. TEE was utilized throughout the procedure allowing real time visualization of device deployment, release and assessment of closure in 17 dogs. No complications occurred related to TEE. Complete PDA closure was achieved in all dogs. Conclusions and Clinical Importance: TEE provided anatomic information regarding PDA morphology that closely approximated angiographic ductal dimensions while aiding in device deployment, release and confirmation of closure. We conclude that TEE provides complementary anatomical and intraprocedural information and is well tolerated in dogs.     

Transthoracic echocardiographically-guided interventional cardiac procedures in the dog

ObjectivesInterventional cardiac procedures are traditionally performed using fluoroscopy, or, more recently, transesophageal echocardiography (TEE). Neither modality is widely available to practicing cardiologists worldwide. We examined whether balloon valvuloplasty of pulmonic stenosis (PS) and transarterial occlusion of patent ductus arteriosus (PDA) in dogs could be performed safely with transthoracic echocardiography (TTE).AnimalsA prospective consecutive case series of 26 client-owned dogs with PS (n = 10) and PDA (n = 16).MethodsThe cardiovascular procedures were performed using TTE. Each dog was positioned on a standard echocardiography table in right lateral recumbency (dogs with PS) or left lateral recumbency (dogs with PDA). Guide wires, balloon catheters, Amplatz^® Canine Ductal Occluder (ACDO) delivery sheaths, and ACDO were imaged by standard echocardiographic views optimized to allow visualization of the defects and devices.ResultsProcedures were performed successfully without major complications in 20 dogs. In 2 dogs (German shepherds) with Type III PDA, ACDO placement was unsuccessful; 2 other German Shepherds were excluded from the procedure because their ductal diameters, measured echocardiographically, exceeded the limits of the maximal ACDO size. Two dogs weighing ≤3.5 kg had suboptimal echocardiographic visualization of the PDA and were considered too small for safe ACDO deployment. All intravascular devices at the level of the heart and great vessels appeared hyperechoic on TTE image and could be clearly monitored and guided in real-time.ConclusionsWe have demonstrated that TTE monitoring can guide each step of pulmonic balloon valvuloplasty and PDA occlusion without fluoroscopy.     

Catheter closure of patent ductus arteriosus in dogs: variation in ductal size requires different techniques

Background:Catheter closure of patent ductus arteriosus Botalli (PDA) is increasingly replacing traditional surgical ligation via thoracotomy. A variety of techniques have been described in dogs, although the technique and implant chosen may depend on the minimum ductus diameter.Objectives:To evaluate the feasibility and treatment of choice of catheter closure of large and small PDAs in dogs.Methods:In 16 dogs with a PDA, catheter closure was performed using transarterial embolisation using detachable or free coils, or transvenously using an Amplatzer, duct occluder (ADO).Results:In 8 dogs, closure of PDA with a minimum diameter of < 4 mm was achieved using detachable coils; 2 or more coils were required in 3 dogs. In 5 dogs with minimum ductus diameters of > 4 mm, detachable coils were not applicable. In one of these dogs, (incomplete) surgical ligation was performed and later a free coil placed for complete closure. In 2 dogs with moderately large PDA (5 mm), several free coils were implanted. Complete closure was not achieved in either dog and transient haemolysis occurred as a complication. In 2 dogs with a very large PDA (6 mm), implanted free coils embolised to pulmonary arteries and closure was then achieved using an ADO. In 3 dogs with an excessively large PDA (7.5-10 mm) closure was successfully achieved using an ADO with no complications.Conclusions:Coil embolisation is readily feasible for closure of PDA < 4 mm, less feasible for PDA < 5 mm and unlikely to be feasible to close PDA > 5 mm. Detachable coils are safe for PDA < 4 mm, and the ADO is an excellent device for PDA > 5 mm.     

Successful transcatheter retrieval of embolized Amplatz Canine Duct Occluders in two dogs

Transcatheter occlusion of patent ductus arteriosus (PDA) using an Amplatz® Canine Duct Occluder (ACDO) is routinely performed in dogs. Pulmonary embolization of the device is a rarely reported complication of this procedure. We report here the first two cases of successful transcatheter retrieval of an embolized ACDO. An 8-month-old, 21-kg, German shepherd (case 1) was referred for pulmonary edema secondary to a large PDA with left-to-right shunting. After medical stabilization, an emergency procedure for PDA closure was recommended. An 8-mm ACDO was deployed under general anesthesia. The device was released after confirming its stability with a gentle tug test but migrated into the pulmonary trunk. A 10-mm ACDO was subsequently successfully deployed and released. Vascular access was then obtained from the right jugular vein so that a vascular snare could be used to capture the ACDO waist and pull it back toward the right ventricle and then the right atrium. It was then removed through the jugular vein. The dog recovered uneventfully and was discharged after confirmation of complete ductal occlusion. The same complication occurred in a second case (case 2, asymptomatic 6-month-old, 7.9-kg, cocker spaniel), and a similar procedure was used to successfully retrieve the embolized device. Both dogs are still doing well 9 and 21 months, respectively, after the procedure. These cases illustrate that transcatheter retrieval of ACDO devices embolized in the pulmonary artery using vascular snares is technically feasible in the dog.     

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.     

Minimally invasive per-catheter patent ductus arteriosus occlusion in dogs using a prototype duct occluder

BACKGROUND: Per-catheter patent ductus arteriosus (PDA) occlusion in dogs with devices intended for humans is associated with technical difficulties, high rates of procedure abandonment, device migration, and residual ductal flow. HYPOTHESIS: Use of a custom-made canine duct occluder (Amplatz Canine Duct Occluder, ACDO) would be feasible in dogs of varying weights and somatotypes and effective in occluding a wide range of PDA shapes and sizes. ANIMALS: Eighteen client-owned dogs of various breeds with PDA. Weights ranged from 3.8 to 32.3 kg (median, 17.8 kg), and angiographic minimal ductal diameters ranged from 1.1 to 6.9 mm (median, 3.7 mm). Ductal morphologies included types IIA, IIB, and III. METHODS: Per-catheter PDA occlusion with the ACDO was performed in all dogs. Persistent or recurrent ductal flow was assessed at the end of the procedure by angiography and at 1 day, 3 months, and >or=12 months after the procedure by echocardiography. RESULTS: Successful ACDO placement was achieved in all 18 dogs. One dog required a 2nd procedure with a larger ACDO after the 1st device migrated to the pulmonary vasculature. Complete occlusion was confirmed in 17 of 18 dogs during the procedure, as well as at 1 day and 3 months after the procedure, and in 12 of 13 dogs evaluated at >or=12 months after the procedure. CONCLUSIONS AND CLINICAL IMPORTANCE: Per-catheter PDA occlusion in dogs with the ACDO is feasible and effective in dogs of a wide range of weights and somatotypes and with PDAs of varying shapes and sizes.     

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.     

Comparison of the incidence of residual shunting between two surgical techniques used for ligation of patent ductus arteriosus in the dog

OBJECTIVE: To compare the incidence of residual patent ductus arteriosus (PDA) flow after ligation using 2 different dissection techniques: a standard dissection and a method described by Jackson and Henderson. STUDY DESIGN: A randomized, prospective study. ANIMALS: Thirty-five dogs admitted for surgical correction of a left to right shunting PDA. METHODS: Dogs were randomly assigned: 19 to a standard dissection technique (group S) and 16 to the Jackson and Henderson dissection group (group JH). RESULTS: Gender ratio, age at surgery, and diameter of the ductus were not statistically different between groups. Breed distribution was also similar. Because 1 dog had fatal intraoperative hemorrhage, only 34 dogs were available for residual flow comparisons. Twenty-one percent of group S dogs had residual flow compared with 53% in group JH. Whereas no intraoperative complications occurred in group S, 3 were encountered in group JH. CONCLUSIONS: The incidence of residual flow was higher when the Jackson and Henderson dissection was used for PDA ligation compared with a standard method of dissection. This was probably because of entrapment of loose connective tissue within the medial aspect of the ligature, impeding complete closure of the ductus. CLINICAL RELEVANCE: Ideal PDA closure should result in no residual ductal flow to prevent possible adverse long-term sequelae, such as recanalization and infective endocarditis.     

Patent ductus arteriosus: anatomy and surgery in a cat

A 5-month-old cat with patent ductus arteriosus (PDA) and probable small ventricular septal defect had severe cardiomegaly and congestive heart failure. The cat improved slightly with medical therapy and markedly after surgical closure of the ductus. A 4th left intercostal space thoracotomy gave good exposure. The external anatomy of the PDA was similar to that of a short, wide PDA in dogs; however, the internal aortic orifice was situated more cranial than in dogs, as evidenced by preoperative cardiac catheterization. Examination 1 year later showed marked reductions in heart size and electrocardiographic amplitude. The cat was 1 of 3 with clinically diagnosed PDA at the University of Pennsylvania from 1968 to 1980. The prevalence of PDA in 14,224 cats (0.2/1,000) was significantly less than in 68,049 dogs (4.7/1,000).     

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.     

Transarterial coil embolization of patent ductus arteriosus in small dogs with 0.025-inch vascular occlusion coils: 10 cases

Patent ductus arteriosus (PDA) is the most common congenital cardiac disease in the dog and generally leads to severe clinical signs, including left-sided congestive heart failure. Historically, definitive treatment consisted of surgical ligation; however, the use of vascular occlusion devices by minimally invasive techniques has gained popularity in veterinary medicine during the past decade. Adequate vascular access is a major limiting factor for these minimally invasive techniques, precluding their use in very small dogs. The clinical management of PDA with 0.025-in vascular occlusion coils in a minimally invasive transarterial technique in 10 dogs is described. The dogs were small (1.38 +/- 0.22 kg), were generally young (6.70 +/- 5.74 months), and had small minimal ductal diameters (1.72 +/- 0.81 mm from angiography). Vascular access was achieved, and coil deployment was attempted in all dogs with a 3F catheter uncontrolled release system. Successful occlusion, defined as no angiographic residual flow, was accomplished in 8 of 10 (80%) dogs. Successful occlusion was not achieved in 2 dogs (20%), and both dogs experienced embolization of coils into the pulmonary arterial tree. One of these dogs died during the procedure, whereas the other dog underwent a successful surgical correction. We conclude that transarterial PDA occlusion in very small dogs is possible with 0.025-in vascular occlusion coils by means of a 3F catheter system and that it represents a viable alternative to surgical ligation. The risk of pulmonary arterial embolization is higher with this uncontrolled release system, but this risk may decrease with experience.     

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.     

Delayed embolization of an Amplatz® canine duct occluder in a dog

A 5-year old, 5.8 kg, castrated male Pomeranian was diagnosed with a type IIa patent ductus arteriosus (PDA) with a minimal ductal diameter of 3.5 mm and ampulla width of 7.1 mm based on angiographic assessment. A 6 mm Amplatz^® Canine Duct Occluder (ACDO) was deployed within the PDA. Once deployed, the device assumed it's native shape and back-and-forth maneuvering was performed with the delivery cable to assess device stability. Device position and complete occlusion were confirmed with both angiography and transesophageal echocardiography prior to and after release of the device. The device location was confirmed within the ductus arteriosus by echocardiography prior to discharge. The dog was discharged with instructions for strict activity restriction. Two days after discharge, the dog was left unsupervised in the backyard and shortly afterwards was found coughing with severe respiratory distress. The dog was evaluated at an emergency hospital and thoracic radiographs documented embolization of the ACDO to the main pulmonary artery along with a severe alveolar pattern throughout the right lung fields. Shortly after obtaining thoracic radiographs, the dog experienced cardiopulmonary arrest with unsuccessful resuscitation. This case describes a possible complication of transcatheter PDA occlusion with an ACDO, which has not been previously reported. An incident report, or catalog of adverse events with these devices, may prove useful in identifying additional fatal complications that others may have encountered, but are not reported in the literature. The report of this complication emphasizes the importance of strict activity restriction after device placement in dogs.     

Evaluation of survival rate and prognostic indicators for surgical treatment of left-to-right patent ductus arteriosus in dogs: 52 cases (1995-2003)

OBJECTIVE: To determine factors associated with long-term survival in dogs treated surgically for patent ductus arteriosus (PDA). DESIGN: Retrospective case series. Animals-52 dogs treated surgically for left-to-right shunting PDA. PROCEDURE: Data pertaining to age, breed, sex, body weight, clinical examination findings, type and duration of medical treatment, results of thoracic radiography and echocardiography, and surgical and postoperative complications were collected from records. Follow-up information was obtained from medical records or telephone interviews with owners or referring veterinarians. RESULTS: 22 dogs had mitral valve regurgitation. Mean weight and age were not significantly different between dogs with or without mitral valve regurgitation. Twenty-four (46.2%) dogs had clinical signs related to cardiac insufficiency. Left atrial dilatation was observed in 56.3% of dogs that were radiographed. Sonographic imaging was used to diagnose left atrial dilatation in 23 dogs and left ventricular dilatation in 25 dogs. The 1- and 2-year survival rates were 92% and 87%, respectively. Diagnosis of mitral valve regurgitation before surgery was not associated with the probability of survival. Age, weight, lethargy, preoperative treatment with angiotensin-converting enzyme inhibitors, and right atrial dilatation on radiographs at the time of surgery were negatively associated with probability of survival. CONCLUSIONS AND CLINICAL RELEVANCE: Surgical treatment of PDA was curative in young dogs without clinical signs of heart failure. Surgical correction of PDA should be recommended as early as possible after diagnosis, and mitral valve regurgitation is not a contraindication for surgery.     

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.     

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.     

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.     

Long-term follow-up after transvenous single coil embolization of patent ductus arteriosus in dogs

Background: Long‐term follow‐up studies after interventional therapy of patent ductus arteriosus (PDA) in dogs are rare. Hypothesis: Transvenous PDA embolization with a single detachable coil is a highly effective method in patients with an angiographically determined PDA ≤ 4.0 mm. Animals: Twenty‐eight dogs with an angiographic PDA ≤ 4.0 mm were included. Methods: Prospective follow‐up study after PDA coil embolization. Results: The median follow‐up time was 792 days (range, 2–3, 248 days). The rate of complete closure demonstrated by Doppler color flow was 54% at day 3 after intervention and the final cumulative rate was 71%. The rate of complete closure was significantly different between small and moderately sized PDA over the study period (P < .0001) and finally was 100 and 50%, respectively. In 16 dogs with complete closure, no recanalization was found. Disappearance of the continuous heart murmur was found in 89% after 3 days, and this increased to a final cumulative rate of 96%. Indexed left ventricular internal diameter in diastole (LVDd‐I) decreased significantly (P < .0001). In the group with moderately sized PDA, a significant difference (P= .0256) was seen in LVDd‐I between patients with and without residual shunt after exclusion of patients with persistent severe mitral valve regurgitation. Conclusion and Clinical Importance: Long‐term follow‐up after single coil embolization showed complete closure in all small PDA but a residual shunt with mild hemodynamic consequences was present in half of the moderately sized PDA.