Transthoracic echocardiographically-guided interventional cardiac procedures in the dog

Transesophageal echocardiography-guided percutaneous patent ductus arteriosus closure without fluoroscopy

OBJECTIVES

A retrospective study was performed to summarize the experience of transcatheter closure of patent ductus arteriosus (PDA) through the right femoral vein under the guidance of transesophageal echocardiography (TEE).

METHODS

From January 2019 to September 2021, 75 children who underwent PDA closure through the right femoral vein under the guidance of TEE were included. The guide wire and delivery sheath were inserted through the ductus arteriosus into the descending aorta via the right femoral vein, and the occluder was subsequently deployed. After discharge, all patients were required for outpatient follow-ups at 1, 3, 6 and 12 months.

RESULTS

In this group, patients were older than 10 months of age and body weight greater than 8 kg. Among 75 cases with PDA, 63 were tubular type and 12 were conical type. The mean operative time was 40.2 ± 7.3 min. The size of PDA occluder ranged from 4-6 to 12-14 mm. The mean hospital stay was 5.5 ± 0.5 days. One month after discharge, there were 4 cases with a mild residual shunt. Eventually, the residual shunt was not observed during 3, 6, and 12 months of follow-up.

CONCLUSIONS

PDA closure under the guidance of TEE can be performed through the right femoral vein successfully and effectively. This procedure has no contrast agent usage, radiation exposure, or open incisions.

Transthoracic echo-guided pacemaker implantation reduces fluoroscopic use in dogs

Echocardiographic guidance provides an alternative method when fluoroscopy is unavailable, equipment or power failure of fluoroscopic equipment during a procedure occurs or to decrease radiation risk. Recently, transthoracic (TTE) and transesophageal echocardiography were reported as an alternative method to guide interventional procedures in dogs. Therefore, we hypothesized that TTE could be used as an alternative method to visualize endocardial leads during pacemaker implantation in dogs, largely avoiding the use of fluoroscopy. A prospective consecutive case series of pacemaker implantation was performed using TTE guidance. The endocardial lead was imaged by TTE during its intracardiac advancement until the lead tip was positioned at the right ventricular apex. Echocardiographic right parasternal views, optimized to visualize the pacing lead, were used, starting with a short axis image of the right atrium and ending with a long axis view of the right ventricle (RV) optimized to image the RV apex. Proper lead placement was confirmed by both capture threshold, impedance and fluoroscopy. Twenty-one pacemaker implantation procedures by TTE monitoring were successfully performed. The TTE guidance provided images of a quality sufficient to clearly monitor implantation in real-time and allowed for immediate corrections to pacing lead malpositioning or excessive looping. Fluoroscopy was used to confirm the correct placement of the lead that was guided echocardiographically in the initial three procedures, after which a single radiographic image (no cine-mode) was used to identify lead placement and redundancy in the remaining eighteen cases. Static imaging (radiography using the fluoroscope) was used to assess the proper lead redundancy in all procedures because this cannot be evaluated echocardiographically. Pacemaker leads were successfully implanted in the RV of dogs using TTE monitoring. A larger cases series is needed for validation of safety and effectiveness of TTE during this interventional procedure in dogs.

Anatomy, baseline characteristics, and procedural outcome of patent ductus arteriosus in German Shepherd dogs

Background

German Shepherd dogs (GSD) are predisposed to developing patent ductus arteriosus (PDA) and are reportedly prone to type III (tubular) PDA anatomy. Dogs with type III anatomy are not considered favorable candidates for device‐based intervention.

Objective

To describe the PDA anatomy, baseline characteristics, and procedural outcome of GSD with PDA.

Animals

Twenty‐eight client‐owned GSD.

Methods

Retrospective review of medical records of 28 GSD diagnosed with PDA that underwent surgical ligation or transcatheter device closure between 2007 and 2017.

Results

German Shepherd dogs with PDA often presented with clinical signs (50%), concurrent congenital heart disease (35.7%), and arrhythmias (29%). Dogs were typically mature at presentation (median age, 12.1 months) and evenly distributed by sex (57% female). The PDA anatomy was classified in 24 of 28 GSD, with type II anatomy being most common (21/24). Three dogs had unusual anatomy (type IV in 1, type V in 2). Median minimal ductal diameter (MDD) in this population was larger than previously reported in a mixed population and ranged between 4.4 and 4.9 mm depending upon imaging modality. Successful closure was achieved using an Amplatz canine duct occluder (ACDO) in 22 dogs or by surgical ligation in 6 dogs. No cases of type III anatomy were confirmed.

Conclusions and Clinical Importance

The majority of GSD in this population had type II PDA anatomy that was amenable to ACDO deployment. Predisposition for large MDD and occasional, unusual PDA anatomy suggests that transesophageal echocardiography may be beneficial for optimal procedural planning in this breed.

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.

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.

Parâmetros ecocardiográficos em cães saudáveis tratados com acepromazina, meperidina e sua associação

RESUMO Objetivou-se avaliar os efeitos da tranquilização com meperidina, acepromazina e de sua associação sobre os parâmetros ecocardiográficos em cães. Foram utilizados 12 cães adultos, da raça Rottweiler, submetidos ao exame ecocardiográfico sem utilização de sedação (controle - TC) e a três protocolos de tratamento, utilizando-se meperidina (TM), acepromazina (TA) e a associação dos medicamentos (TMA). As variáveis foram analisadas pelo teste de Tukey (P<0,05). Observou-se que as médias obtidas na onda A do fluxo mitral em TA e TMA diminuíram significativamente com relação ao TM, que não diferiu do TC. Houve uma diminuição significativa no valor de movimento anular mitral (MAM) e excursão sistólica do plano anular tricúspide (ESPAT) no TA. Não houve diferença significativa para os valores de fração de encurtamento (FE) entre TA e os demais tratamentos. Entretanto, observou-se que 57,3% dos cães apresentaram valores de FE abaixo da normalidade. As alterações encontradas podem ser decorrentes dos efeitos hipotensores da acepromazina utilizada de forma isolada. Conclui-se que a meperidina ou sua associação com acepromazina não alteram os parâmetros ecocardiográficos em cães saudáveis e que a acepromazina, utilizada isoladamente, causa alteração nos parâmetros de função sistólica dos cães, não sendo recomendada para a contenção química dos cães submetidos ao ecocardiograma, o que poderia levar à má interpretação do exame.

Relationship between Device Size and Body Weight in Dogs with Patent Ductus Arteriosus Undergoing Amplatz Canine Duct Occluder Deployment

Background

Deployment of the Amplatz Canine Duct Occluder (ACDO) is the preferred method for minimally invasive occlusion of patent ductus arteriosus (PDA) in dogs, with appropriate device sizing crucial to successful closure. Dogs of any body weight can be affected by PDA.

Objectives

To describe the range of ACDO sizes deployed in dogs of various body weights for improved procedural planning and inventory selection and to investigate for correlation between minimal ductal diameter (MDD) and body weight.

Animals

A total of 152 dogs undergoing ACDO deployment between 2008 and 2016.

Methods

Body weight, age, breed, sex, and MDD obtained by angiography (MDD‐A), MDD obtained by transesophageal echocardiography (MDD‐TEE), and ACDO size deployed were retrospectively evaluated.

Results

Correlation between body weight and ACDO size, MDD‐A and MDD‐TEE was poor, with R‐squared values of 0.4, 0.36, and 0.3, respectively. Femoral artery diameter in the smallest population of dogs placed inherent limitations on the use of larger device sizes, with no limitations on the wide range of device sizes required as patient size increased. The most commonly used ACDO devices were size 3 through 6, representing 57% of the devices deployed within the entire study population.

Conclusions and Clinical Importance

Patent ductus arteriosus anatomy varies on an individual basis, with poor correlation between MDD and body weight. Weight‐based assumptions about expected ACDO device size for a given patient are not recommended.

Design and verification of a shape memory polymer peripheral occlusion device

Shape memory polymer foams have been previously investigated for their safety and efficacy in treating a porcine aneurysm model. Their biocompatibility, rapid thrombus formation, and ability for endovascular catheter-based delivery to a variety of vascular beds makes these foams ideal candidates for use in numerous embolic applications, particularly within the peripheral vasculature. This study sought to investigate the material properties, safety, and efficacy of a shape memory polymer peripheral embolization device in vitro. The material characteristics of the device were analyzed to show tunability of the glass transition temperature (Tg) and the expansion rate of the polymer to ensure adequate time to deliver the device through a catheter prior to excessive foam expansion. Mechanical analysis and flow migration studies were performed to ensure minimal risk of vessel perforation and undesired thromboembolism upon device deployment. The efficacy of the device was verified by performing blood flow studies that established affinity for thrombus formation and blood penetration throughout the foam and by delivery of the device in an ultrasound phantom that demonstrated flow stagnation and diversion of flow to collateral pathways.

Chitosan hemostatic dressing for control of hemorrhage from femoral arterial puncture site in dogs

Removal of an introducer-sheath from a femoral artery after completing transarterial embolization of a patent ductus arteriosus can cause life-threatening hemorrhage in dogs. In the present study, the effectiveness of chitosan acetate dressing in 10 experimental dogs was tested. Under general anesthesia, an introducer-sheath was placed into the femoral artery with percutaneous puncture using Seldinger's technique. The outer diameter of the introducer-sheaths varied from 3.0 to 4.0 mm with an introducer/artery ratio of 80 to 123%. The artery's diameter was measured using ultrasonography. Following removal of the introducer-sheath, a chitosan acetate dressing was applied to the wound and held in place with manual compression for 10 min. Successful hemostasis was reached on 12 arteries. However, on two arteries, hemorrhage was uncontrollable and led to a hypovolemic shock during 10 min of manual compression. Possible causes of the negative outcome in two dogs were their old age and an introducer-sheath with a too large diameter. The chitosan acetate dressing was easy to use and the artery remained patent. Dogs could walk directly after recovery from anesthesia and their femoral arteries were saved. In conclusion, the outer diameter of the introducer-sheath should not exceed 3 mm or the inner diameter of the artery.

Transesophageal echocardiography as the sole guidance for occlusion of patent ductus arteriosus using a canine ductal occluder in dogs

Background

Transcatheter occlusion of patent ductus arteriosus (PDA) is usually performed by fluoroscopy alone or together with transesophageal echocardiography (TEE). Transthoracic echocardiography (TTE) guidance has been used for deployment of Amplatz Canine Ductal Occluder (ACDO), but sometimes is limited by suboptimal acoustic windows. Transesophageal echocardiography can overcome such issues and provides higher image resolution at the level of the great vessels.

Objectives

To determine if TEE without fluoroscopy could be used to successfully perform ductal occlusion for the treatment of PDA in dogs.

Animals

Twenty client‐owned dogs with PDA.

Methods

A prospective consecutive case series of PDA occlusion was performed using only TEE guidance. Dogs were positioned in right lateral recumbency and the TEE probe was positioned to visualize the descending aorta, PDA, and pulmonary artery. The guide wire, long introducer sheath, and ACDO were imaged by TEE to direct deployment.

Results

Ductal occlusion was performed successfully without need for fluoroscopy and without complications in 19 dogs. One dog required a second larger ACDO because of embolization of the first device 18 hours after positioning.

Conclusions and Clinical Importance

We have demonstrated that TEE monitoring without concurrent fluoroscopy can guide each step of transcatheter ACDO embolization thereby providing an alternate method of visualization for this procedure. Use of TEE alone can reduce radiation exposure or is an option when fluoroscopy is not available, and, therefore, should be evaluated in a larger case series to better assess procedural failure rates.

Promotion of artery occlusion in dogs by percutaneous rotational atherectomy

BACKGROUND

This study aims to offer experimental data and indirect evidences for the application of percutaneous rotational atherectomy to treat patent ductus arteriosus (PDA).

METHODS

Eleven dogs (6 male dogs and 5 female dogs; aged 14-20 months, with an average of 16.7±3.2 months; weight 20-25 kg, with an average of 22.7±2.5 kg) were enrolled in this study. The diameters of the left and right arteries ranged from 3.2 to 4.8 mm (average 3.9±0.6 mm) on percutaneous angiography. Percutaneous rotational atherectomy with proper rotablator (the size was 1-1.5 mm larger than the artery diameter) was performed in the arterial intima. After 4 weeks from percutaneous rotational atherectomy, arteriography was conducted to observe the changes in artery diameter. Then all dogs were sacrificed and the pathologic examination was conducted on the left and right axillary arteries.

RESULTS

There were obvious changes with different degrees in 22 arteries, including 8 arteries with complete occlusion and 12 arteries with stenosis (≥2/3, 1/2, and 1/3 stenosis in 4, 4, and 4 arteries, respectively). The occlusion rate was 36.4% and the total effective rate was 90.9%. It was considered failure in other 2 arteries with <1/3 of stenosis.

CONCLUSIONS

Percutaneous rotational atherectomy of arterial intima can promote the occlusion of arteries. This has provided a new choice for the treatment of PDA.

Transoesophageal echocardiography in the dog

Transoesophageal echocardiography (TEE) allows imaging of the heart through the oesophagus using a special transducer mounted on a modified endoscope. The proximity to the heart and minimal intervening structures enables the acquisition of high-resolution images that are consistently superior to routine transthoracic echocardiography and optimal imaging of the heart base anatomy and related structures. TEE provides high-quality real-time imaging free of ionizing radiation, making it an ideal instrument not only for diagnostic purposes, but also for monitoring surgical or minimally invasive cardiac procedures, non-cardiac procedures and critical cases in the intensive care unit. In human medicine, TEE is routinely used in these settings. In veterinary medicine, TEE is increasingly used in referral centres, especially for perioperative assessment and guidance of catheter-based cardiovascular procedures, such as patent ductus arteriosus, balloon valvuloplasty, and atrial and ventricular septal defect occlusion with vascular devices. TEE can also aid in heartworm retrieval procedures. The purpose of this paper is to review the current uses of TEE in veterinary medicine, focusing on technique, indications and complications.