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

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.

The Patent Ductus Arteriosus in Adults with Special Focus on Role of CT

The primary imaging modality for the diagnosis of patent ductus arteriosus (PDA) is echocardiography. However, CT may be the technique on which an incidental PDA is first recognized because of the increasing number of chest CT scans performed for a variety of causes. Identification of PDA on CT may lead to earlier closure using a PDA occluder device. Immediate identification of incidental PDA is important, but a high rate of missed diagnosis of PDA has been reported due to its small size and anatomic location. In addition, echocardiography may overlook the presence of even a large PDA due to decrease in the amount of shunting through the PDA caused by high pulmonary artery pressures. This review provides the basic CT anatomy and clinical perspective of PDA, and discusses the role of CT in the evaluation of PDA as well as methods to avoid overlooking a small PDA on CT.

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.

Periprocedural vascular access complications associated with percutaneous femoral arterial access using the modified Seldinger's technique in dogs during cardiac catheterization: a single-center experience

BACKGROUND

The primary objective of this study is to evaluate the peri-procedural major and minor complications associated with percutaneous femoral arterial access using modified Seldinger's technique in dogs that underwent cardiac catheterization.

METHODS

Medical records of 62 client owned dogs that underwent percutaneous femoral arterial access for interventional cardiac procedures were retrospectively evaluated. Post-procedural manual compression was used for hemostasis. Peri-procedural vascular access complications (that occurred from procedure time to discharge) were evaluated. Vascular access complications were divided into two groups: minor complications that did not require specific therapy and major complications that did require an intervention to address the complication associated with vascular access.

RESULTS

The minor complication rate was 30.6% (19/62) with most dogs experiencing minor bruising and small hematomas. The major complication rate was 3.2% (2/62). Both major complications were associated with bleeding with one dog requiring blood transfusion and the other dog requiring fluid therapy. No peri-procedural mortality associated with vascular access was noted.

CONCLUSION

This retrospective study suggests that percutaneous femoral arterial access using the modified Seldinger's technique with post-procedural manual compression for hemostasis is viable option for vascular access during cardiac catheterization and associated with no peri-procedural mortality in dogs. The lower rate of complications noted in this study may be related to operator experiences and as such complication rate at a single center may not reflect the experience at other centers.

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.

An unusual morphology of patent ductus arteriosus in a dog

A 12-week old, entire female Border terrier weighing 3·5 kg was presented for investigation of a continuous left heart base murmur. The clinical presentation and preoperative echocardiogram were consistent with a standard morphology of patent ductus arteriosus (PDA) but a discrete ductal vessel was not identified during surgical dissection. Surgery had to be abandoned due to deterioration of the patient's condition under general anaesthesia which led to cardiorespiratory arrest and death despite attempts at resuscitation. Necropsy identified a recess within the wall of the aorta communicating with the pulmonary artery via an ostium at the heart base which determined this structure as an intramural PDA. This morphology of PDA is previously unreported. This report demonstrates that an intramural PDA is not readily identifiable surgically because of the absence of a discrete ductal vessel and it is important to appreciate that unusual morphologies of PDA may occur.

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.

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.

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.