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

Development of a three-dimensional computer model of the equine heart using a polyurethane casting technique and in vivo contrast-enhanced computed tomography

INTRODUCTION/OBJECTIVES

Insight into the three-dimensional (3D) anatomy of the equine heart is essential in veterinary education and to develop minimally invasive intracardiac procedures. The aim was to create a 3D computer model simulating the in vivo anatomy of the adult equine heart.

ANIMALS

Ten horses and five ponies.

MATERIALS AND METHODS

Ten horses, euthanized for non-cardiovascular reasons, were used for in situ cardiac casting with polyurethane foam and subsequent computed tomography (CT) of the excised heart. In five anaesthetized ponies, a contrast-enhanced electrocardiogram-gated CT protocol was optimized to image the entire heart. Dedicated image processing software was used to create 3D models of all CT scans derived from both methods. Resulting models were compared regarding relative proportions, detail and ease of segmentation.

RESULTS

The casting protocol produced high detail, but compliant structures such as the pulmonary trunk were disproportionally expanded by the foam. Optimization of the contrast-enhanced CT protocol, especially adding a delayed phase for visualization of the cardiac veins, resulted in sufficiently detailed CT images to create an anatomically correct 3D model of the pony heart. Rescaling was needed to obtain a horse-sized model.

CONCLUSIONS

Three-dimensional computer models based on contrast-enhanced CT images appeared superior to those based on casted hearts to represent the in vivo situation and are preferred to obtain an anatomically correct heart model useful for education, client communication and research purposes. Scaling was, however, necessary to obtain an approximation of an adult horse heart as cardiac CT imaging is restricted by thoracic size.

Evaluation of non-ECG and ECG-gated computed tomographic angiography for three-dimensional printing of anomalous coronary arteries in dogs with pulmonic stenosis

INTRODUCTION/OBJECTIVES

Coronary artery abnormalities are described sporadically in dogs, most commonly with pulmonic stenosis. Computed tomographic angiography (CTA) allows non-invasive assessment of coronary anatomy. Three-dimensional (3D) models improve the understanding and visualization of spatially complex anatomy. The study objective was to evaluate coronary artery anomalies using CTA imaging and using rapid prototyping technology to create life-sized coronary artery models of these studies.

ANIMALS, MATERIAL AND METHODS

Combined retrospective case and prospective pilot study. Inclusion criteria were dogs with reported coronary artery anomalies. The CTA data sets were imported into a medical imaging framework for the analysis of the coronary arteries and into a 3D-planning and printing software for creating printable 3D models. The 3D models were printed using fusion deposition modeling technology.

RESULTS

Six male dogs with an R2A coronary artery anomaly and pulmonic stenosis diagnosed by CTA were included. Electrocardiogram (ECG)-gated CTA allowed better identification of anomalous coronary arteries than non-gated CTA. In all dogs, the right coronary artery had a smaller diameter than the left and the left coronary artery or its branch had a prepulmonic course. All ECG-gated studies were 3D printed while non-gated studies were not printable due to CTA artifacts.

CONCLUSION

In dogs, CTA is effective for diagnosis of coronary artery anomalies. Printed 3D models of ECG-gated CTA studies were of excellent quality and allowed direct visualization of abnormal coronary artery anatomy. The usefulness of these models to improve the understanding of anomalous coronary artery anatomy could be evaluated in future studies.

A pictorial view of the three-dimensional representation and comparative two-dimensional image orientation derived from computed tomography angiography in a dog with a patent ductus arteriosus

Patent ductus arteriosus (PDA) occlusion is one of the more common cardiovascular procedures performed in dogs. Two-dimensional imaging has been the primary method of visualizing the PDA and is the basis of its morphologic description. Transesophageal echocardiographic imaging has further characterized the three-dimensional (3D) variation in ductal morphology and shape (circle, oval). An accurate assessment of the shape and dimensions of a PDA in an individual dog is important when making decisions about definitive closure. Ductal measurements from angiography and echocardiography have not been found to be interchangeable, likely related in part to the static two-dimensional measurement of a 3D structure. We describe the use of computed tomography angiography (CTA) images imported into three software programs as a tool to provide 3D information about PDA anatomy including a comparison to images obtained from classic two-dimensional imaging modalities. These images provide an example of thorax and heart position related to transducer position and the orientation of image acquisition to demonstrate why measurements do not always compare. Additionally, 3D images are useful as a training tool and in the development of devices and training opportunities. Multidimensional imaging provides a unique representation of the 3D anatomical structure of the ductus arteriosus as displayed in these images from a dog with a PDA.

A Patient-Specific Hollow Three-Dimensional Model for Simulating Percutaneous Occlusion of Patent Ductus Arteriosus

Percutaneous catheter closure of patent ductus arteriosus (PDA) is difficult when the ductus is large and long or shows calcification. We created a patient-specific 3-dimensional (3D) model for PDA, with which we simulated device deployment, thereby selecting the device/size in a patient-by-patient manner. We assessed whether this 3D model is effective for catheter PDA closure.The 3D model was created in this institute, requiring 3 days and 90 US dollars. After its introduction, 7 consecutive patients (the study group) with severe PDA underwent closure with the aid of the 3D model. The control group consisted of 4 patients before 3D-model introduction, with all having severe PDA: the requirement of computed tomography was considered a criterion of severe or difficult-procedure-requiring PDA.In all study group patients, the devices/sizes could be pre-selected based on the simulation, whereas devices were changed during the procedure in 2 of 4 in the control group. In the study group, compared with the control group, the fluoroscopic (median 31 [interquartile range of 16-42] versus 39 [19-71] minutes, respectively) and total procedural times (median 107 [interquartile range 67-114] versus 124 [78-184] minutes, respectively) were shorter. A questionnaire confirmed the doctors' understanding of the procedure.This 3D model may be effective for percutaneous catheter closure of PDA. This may be especially true in cases of severe or difficult-procedure-requiring PDA.

Transcatheter closure through single venous approach for young children with patent ductus arteriosus: A retrospective study of 686 cases

The objective is to explore the feasibility and safety of transcatheter closure of patent ductus arteriosus (PDA) through single venous approach in Chinese young children.A total of 1088 patients aged between 9 months old to 3 years old who underwent transcatheter closure of PDA from May 2004 to May 2015 were retrospectively reviewed. All the procedures were under ultrasound monitoring. The shape and size of PDA as well as immediate therapeutic results were recorded by angiography and ultrasonography. The size of occluder was individually selected according to the smallest diameter of the PDAs. Echocardiography was respectively performed 3 days, 1month, 6 months, and 12 months after the procedure to evaluate the outcomes.Among the total 1088 children, transcatheter closure of PDA was accomplished through single venous approach that was performed in 686 cases. The average weight and age of the children were 10.9 ± 3.6 kg (5.0-14.3 kg) and 1.8 ± 1.6 years (9 months-3 years), respectively. The fluoroscopic time was about 5.1 to 11.6 minutes. Successful device placement with the initially selected occluder was achieved in 662 cases. In other 14 cases, the procedure was eventually completed after being replaced with a larger occluder; while in the other 10 cases, smaller occluders were applied to replace the initial ones. Technically, all the procedures were successfully performed. All the patients were followed up for 15.6 ± 8.2 years. No serious complications and death were observed during the follow-up.Transcatheter closure of PDA with occluder by single venous approach is an effective and reliable method in vast majority of young children.

Comparative, multidimensional imaging of patent ductus arteriosus and a proposed update to the morphology classification system for dogs

Background

Accurately assessing the morphology and shape of the patent ductus arteriosus (PDA) and obtaining measurements are important to avoid procedural complications.

Objectives

To characterize and compare PDA morphology, shape, and dimensions with angiography and echocardiography.

Animals

25 client‐owned dogs with echocardiographically confirmed PDA.

Methods

Prospective case series. Imaging consisted of single plane angiography, transthoracic echocardiography from the right (TTE‐R) and left (TTE‐L), and two‐dimensional, biplane, and three‐dimensional transesophageal echocardiography (TEE‐2D and TEE‐3D). Measurements included angiographic minimal ductal diameter (MDD), echocardiographic pulmonary ostium in a single dimension (TTE‐R, TTE‐L, and TEE‐2D) and in perpendicular dimensions (TEE‐3D) with similar measurements of the ampulla 3 mm above the MDD or pulmonary ostium. The morphology and shape of the PDA were characterized.

Results

Catheter‐based occlusion (N = 20) and surgical ligation (N = 5) were performed without complication. Angiographic morphology was classified as type II (N = 19), type III (N = 1), and other (N = 1). Angiographic MDD and TEE‐2D pulmonary ostium measurements were significantly (P = .008) but weakly correlated (r = .56); similar relationships were found for ampulla diameter measurements (P < .0001; r = .75). In general, TEE‐2D did not correlate with other imaging modalities measurements. Based on TEE‐3D measurements, the majority of pulmonary ostium (17/24; 71%) and ampulla (19/24; 79%) were oval.

Conclusions and Clinical Importance

Measurements using different imaging modalities are not interchangeable. TEE‐3D provided an en face view of the PDA that cannot be replicated with other echocardiographic techniques and demonstrated an oval shape in the majority of dogs. We propose an update to the current classification system to include additional PDA morphologies.