Transarterial Ductal Occlusion with the Amplatzer Vascular Plug in 31 Dogs

Granulomatous Inflammation and Pericarditis Induced by Silk Granuloma Related to Previous Surgical Ligation of Patent Ductus Arteriosus in a Dog

Surgical ligation of a patent ductus arteriosus is regarded as a standard treatment approach with a low complication rate if performed by experienced surgeons, and it has been performed successfully for decades in dogs. However, there are no reports describing the clinical symptoms related to granulomatous inflammation after the surgical ligation of the patent ductus arteriosus. This report describes the clinical symptoms caused by granulomatous inflammation and subacute pericarditis in a dog that had undergone the surgical closure of a patent ductus arteriosus 2 years previously. Exploratory thoracotomy was performed for subtotal pericardiectomy, and a biopsy was performed to obtain specimens for histopathological examination and culture tests. The clinical symptoms were relieved after surgery. The persistent leukocytosis improved with steroid administration. This case illustrates that the granulomatous inflammatory response associated with silk suture granuloma is a rare postoperative complication of ductal ligation. In such cases, pericardiectomy can help relieve the clinical symptoms.

Transjugular Patent Ductus Arteriosus Occlusion in Seven Dogs Using the Amplatzer Vascular Plug II

Simple Summary

This study outlines the authors’ experience using the Amplatzer Vascular Plug II device for occlusion of patent ductus arteriosus (PDA) in dogs through a right transjugular approach, never before described in veterinary medicine for this purpose. The obtained results demonstrate that the use of the Amplatzer Vascular Plug II via a transvenous right jugular approach is a feasible and effective method, even in small-sized patients. The authors’ experience is that the transvenous approach is a safe and effective method for PDA occlusion in dogs. Furthermore, the right jugular approach provides easier and faster vascular access than the femoral one. The authors affirm that this approach, together with the properties of the Amplatzer Vascular Plug II and its wide size selection, potentially provide a novel method that can complement the current available methods for transcatheter PDA occlusion.

Abstract

Although vascular plugs for the closure of patent ductus arteriosus (PDA) have been validated in dogs, studies are lacking on its use as a first-choice device with a transjugular approach. The present case series describes the transvenous right jugular embolization of PDA using an Amplatzer Vascular Plug II in seven dogs of different ages, breeds, and body weights. Complete closure of the PDA was demonstrated in all cases. All dogs showed significant hemodynamic reduction of pulmonary overcirculation and left heart size after the procedure and at following echocardiographic check-ups. Transjugular PDA occlusion using an Amplatzer Vascular Plug II can thus be considered as a safe alternative to the arterial or venous femoral approach using an Amplatzer canine ductal occluder (ACDO), particularly in puppies with small femoral vessels.

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.

Transjugular patent ductus arteriosus occlusion in a cat with a peripheral vascular occlusion device

A five-month-old, intact female domestic shorthair cat was presented to a specialty referral hospital for evaluation of a patent ductus arteriosus. Transvenous embolization of the defect was achieved with a commercially available peripheral vascular plug. The use of vascular plugs for the closure of patent ductus arteriosus has been validated in dogs, yet literature for its use in cats is lacking. The product and procedural details of the device are described.

Key considerations in the approach to congenital heart disease in dogs and cats

Congenital heart disease is an important subset of all cardiovascular disease in dogs and cats that is present at birth and most often detected in young animals but can be diagnosed in adulthood. The range of abnormalities that can occur during development of the heart is vast incorporating simple and complex defects, varying degrees of severity and clinical presentations that include heart failure and cyanosis. While some defects do not result in morbidity in an individual animal, others cause severe clinical signs and death at a young age. Advances in imaging and expanding treatment options offer increasingly more possibilities in the diagnosis and management of congenital heart disease which is the focus of this review. The objective is to provide a broad overview of current practice and highlight key aspects to guide practitioners in their approach to congenital heart disease diagnosis and knowledge of available treatment options.

Transarterial correction of patent ductus arteriosus in small dogs with the Amplatz™ Vascular Plug 4: A pilot study

OBJECTIVES

Determine if the Amplatz™ Vascular Plug 4 (AVP4) can be used to occlude left-to-right shunting patent ductus arteriosus (PDA) in dogs with inadequate arterial vascular access for the Amplatz Canine Duct Occluder (ACDO).

ANIMALS

Six adolescent dogs with PDA whose femoral artery was too small for insertion of a 4 Fr vascular access sheath.

MATERIALS AND METHODS

Standard femoral arterial vascular access and a 4 Fr diagnostic catheter were used to deploy an appropriately sized AVP4 into the PDA of each dog. Successful occlusion was defined as no residual ductal flow and determined by color Doppler echocardiography and angiography.

RESULTS

The AVP4 was successfully deployed, and complete occlusion of the PDA was achieved in all dogs. There were no complications encountered in any of the dogs.

CONCLUSIONS

The AVP4 is a viable option for the correction of PDA in dogs with inadequate arterial vascular access for the ACDO and should be considered as one of the options available for PDA correction in this challenging animal population.

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.

Anaesthetic management and complications of transvascular patent ductus arteriosus occlusion in dogs

OBJECTIVE

To retrospectively analyse the anaesthetic management, complications and haemodynamic changes in a cohort of dogs undergoing transvascular patent ductus arteriosus (PDA) occlusion in a tertiary referral centre (from January 2017 to August 2018).

STUDY DESIGN

Retrospective study.

ANIMALS

A total of 49 client-owned dogs.

METHODS

Anaesthetic records of dogs with PDA that underwent transvascular occlusion of the ductus were reviewed. Anaesthetic complications evaluated included tachycardia [heart rate (HR) > 160 beats minute^-1], bradycardia (HR < 50 beats minute^-1), hypertension [systolic arterial pressure (SAP) > 150 mmHg], hypotension [mean arterial pressure (MAP) < 60 mmHg], hypothermia (<37 °C) and the presence of arrhythmias. Cardiovascular variables [HR and invasive SAP, MAP and diastolic arterial pressure (DAP)] at the time of occlusion device deployment (time 0) were compared with variables at 5 and 10 minutes after deployment. Descriptive statistics, Shapiro-Wilk test and repeated measures analysis of variance followed by a Dunnett's post hoc test were used to analyse the data (p < 0.05).

RESULTS

Crossbreed dogs were the most commonly represented followed by the Cavalier King Charles Spaniel. The median age was 8 (2-108) months, and female dogs were over-represented (65.3%). The most common American Society of Anesthesiologists score was III. Mean duration of anaesthesia was 96 ± 26 minutes and mean surgery time was 58 ± 21 minutes. Acepromazine with methadone was the most commonly used premedication combination (77.6%). Propofol was the most common induction agent (73.5%). General anaesthesia was maintained with isoflurane in oxygen in all dogs. Complications included hypotension (63%), hypothermia (34%), bradycardia (28%), arrhythmias (16%), hypertension (16%) and haemorrhage (2%). MAP and DAP increased significantly 10 minutes after device deployment compared with time 0.

CONCLUSIONS

and clinical relevance: Hypotension was the most common complication reported in dogs undergoing transvascular PDA occlusion. No major adverse events were documented.

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.

Cardiac Interventions in Small Animals: Areas of Uncertainty

There remain areas of uncertainty in optimal technique, preferred candidates, and expected outcome for small animal patients undergoing cardiac intervention. This article highlights issues within interventional cardiology that are in need of study and offers the author's opinion and experience on topics such as variants of pulmonary valve anatomy and alternatives to conventional balloon dilation for pulmonary valve stenosis, patient selection for cutting or high-pressure balloon dilation of aortic valvar or subaortic stenosis, occlusion of patent ductus arteriosus in very small dogs, ductal stenting in conditions with reduced pulmonary blood flow, and alternative considerations for vascular access and closure.

An experimental canine patent ductus arteriosus occlusion device based on shape memory polymer foam in a nitinol cage

Patent ductus arteriosus (PDA) is a congenital cardiovascular defect in which a fetal connection between the aorta and pulmonary artery does not spontaneously close shortly after birth. If left uncorrected serious complications and even death can occur. Surgical ligation is the traditional treatment method; however, it is an invasive procedure, that motivates development of a minimally invasive option. Shape memory polymer (SMP) foams are unique materials that hold promise in the field of minimally invasive occlusion devices. In this work, a prototype nitinol foam cage (NFC) incorporating SMP foams has been designed and evaluated in multiple mechanical and in vitro verification tests. The NFC demonstrated acceptable fatigue resistance in a preliminary strut integrity test, withstanding one million cycles without complete strut fracture. Radial force analysis of both thick- and thin-walled prototype variations generated less vessel distension and wall tension in a vessel mimic compared to a commercial device. The NFCs exhibited negligible in vitro migration, comparable to that of a commercial device, using simplified, ideal models of PDA. Deployment characteristics of the prototypes were evaluated and compared to that of a commercial device when delivered into physiological models of PDA. During mock deployments, a veterinary cardiologist noted that, while deliverable, the thin-walled NFC prototype exhibited poor deployment characteristics, however the thick-walled NFC had deployment characteristics comparable to that of a commercial device. The promising results of this study warrant further investigation of the NFC device for canine PDA closure.

Clinical Characteristics of Adult Dogs More Than 5 Years of Age at Presentation for Patent Ductus Arteriosus

Background

The median age at presentation for dogs with patent ductus arteriosus (PDA) is <6 months of age, and closure is associated with a decrease in heart size and increased survival time, which are not well described in older dogs.

Objectives

To describe the clinical characteristics of dogs with PDA ≥5 years of age at the time of presentation to a veterinary referral hospital.

Animals

35 client‐owned dogs.

Methods

Retrospective case series.

Results

PDA was diagnosed at a median age of 7.4 years (range, 5.1–12.3 years). Females represented 23/35 (65.7%) of the patients. Concurrent heart disease included degenerative mitral valve disease (DMVD; 13), arrhythmias (11), pulmonary hypertension (7), and other congenital defects (2). Cardiomegaly was documented in the majority of dogs consisting of left ventricular enlargement (91%) and left atrial enlargement (86%). Median vertebral heart size in 24 dogs was 12.9 (range, 10.7–18.2). The PDA shunt direction was left‐to‐right in 33 and bidirectional in 2 dogs. Closure was performed in 26 dogs, including 4 with pulmonary hypertension. In 10 dogs receiving furosemide pre‐operatively for management of heart failure, furosemide was discontinued (8) or the dosage decreased (2) at the time of discharge.

Conclusions and Clinical Importance

Adult dogs can present with a left‐to‐right shunting PDA that results in cardiomegaly and clinical signs that can improve or resolve with PDA closure. This improvement is also apparent in dogs with PDA complicated by DMVD. Pulmonary hypertension that does not result in complete right‐to‐left shunting should not be considered a contraindication to closure.

Mechanical and in vitro evaluation of an experimental canine patent ductus arteriosus occlusion device

Patent ductus arteriosus (PDA) is a congenital cardiovascular malformation in which a fetal connection between the aorta and pulmonary artery remains patent after birth. This defect commonly results in clinical complications, even death, necessitating closure. Surgical ligation is the most common treatment but requires a thoracotomy and is therefore invasive. A minimally invasive option is preferable. A prototype device for PDA occlusion which utilizes shape memory polymer foams has been developed and evaluated using mechanical and in vitro experiments. Removal force and radial pressure measurements show that the prototype device exhibited a lower removal force and radial pressure than a commercially available device. The in vitro experiments conducted within simplified and physiological PDA models showed that the prototype does not migrate out of position into the pulmonary artery at either physiological or elevated pressures in multiple model configurations. While the radial pressure and removal force were lower than commercial devices, the device performed acceptably in the in vitro benchtop experiments warranting further prototype development.

Patent ductus arteriosus occlusion in small dogs utilizing a low profile Amplatz® canine duct occluder prototype

OBJECTIVES

To develop procedural methodology and assess the safety, utility and effectiveness of a low profile Amplatz(®) canine duct occluder (ACDO) prototype in dogs deemed too small to undergo ductal occlusion with the commercially-available ACDO device.

ANIMALS

Twenty-one dogs with left-to-right shunting patent ductus arteriosus (PDA). Dogs were ≥1.5 kg but considered too small to accommodate a 6 Fr catheter or 4 Fr sheath within the femoral artery.

METHODS

Prospective canine study using a low profile ACDO prototype delivered through a 4 Fr catheter via a femoral arterial approach. Procedural methods, fluoroscopy time, perioperative complications, and residual ductal flow were evaluated, and angiographic ductal morphology and dimensions were tabulated.

RESULTS

All 21 dogs underwent successful ductal occlusion using the prototype device, 4 Fr catheter, and right femoral artery approach. No perioperative complications or device embolization occurred. The median minimal ductal diameter was 1.9 mm (range, 0.4-3.4), and the median device size deployed was 4 mm (range, 3-6). Complete ductal occlusion was noted in 17 dogs (81%) on post-deployment angiography. Twenty dogs (95%) had no residual flow on echocardiography performed the following day. In the 17 dogs (81%) that returned for a long-term (≥3months) follow-up evaluation, all had complete ductal occlusion based on echocardiography.

CONCLUSIONS

The low profile ACDO prototype is a safe and effective method of PDA occlusion in the small dog. The deployment procedure appears of similar technical difficulty to the commercially available ACDO.

Echocardiographic evaluation of myocardial changes observed after closure of patent ductus arteriosus in dogs

BACKGROUND

Closure of PDA can be associated with echocardiographic changes including deterioration of LV systolic function. Although PDA is commonly encountered in dogs, few comprehensive reports of echocardiographic changes in dogs with PDA closure are available.

OBJECTIVES

To evaluate the short-term echocardiographic changes observed after PDA closure in dogs using strain analysis.

ANIMALS

Seventeen client-owned dogs with left-to-right PDA.

METHODS

Echocardiographic evaluations, including standard echocardiography and two-dimensional tissue tracking (2DTT), were performed before and within 3 days of PDA closure.

RESULTS

Preclosure examination showed LV and left atrial dilatation indicating volume overload as a result of PDA. Closure of PDA resulted in significant reduction of LVIDd (<.0001) and LA/Ao (0.01) without change in LVIDs, suggestive of decreased preload. Postclosure LV systolic dysfunction was observed with significant decreased in FS (<.0001) and strain values (P = .0039 for radial strains, P = .0005 for circumferential strains). Additionally, significant LV dyssynchrony (P = .0162) was observed after closure of PDA.

CONCLUSIONS AND CLINICAL IMPORTANCE

Closure of PDA resulted in decreased preload as a result of alleviation of LV volume overload, which in turn caused transient deterioration of LV systolic function. Additionally, this study demonstrated that strain analysis is load dependent. Therefore, care should be taken when interpreting strain measurements as an indicator of LV systolic function.

Structural and functional cardiovascular changes and their consequences following interventional patent ductus arteriosus occlusion in dogs: 24 cases (2000-2006)

OBJECTIVE

To investigate cardiovascular changes and survival times following complete interventional device occlusion of uncomplicated left-to-right shunting patent ductus arteriosus in dogs.

DESIGN

Retrospective cohort study.

ANIMALS

24 dogs with uncomplicated patent ductus arteriosus that was fully occluded and reevaluated within 24 hours, approximately 3 months, and 1 year after the procedure.

PROCEDURES

Information on medical history, diagnostic imaging findings, treatment received, and survival times were obtained from medical records. Patients were allocated into 2 groups on the basis of age (< 1 year [n = 14] and ≥ 1 year [10]) at the time of the procedure. Additional follow-up information was obtained through interviews of owners and referral veterinarians.

RESULTS

Following ductal occlusion, decreases were detected in vertebral heart scale size, left ventricular chamber diameter in diastole and in systole, left atrial dimension, fractional shortening, aortic velocity, and ventricular wall thickness. There were no differences between age groups for postocclusion changes except vertebral heart scale size. Systolic dysfunction was detected in 14 (58%) patients on the final visit. Median survival time for all dogs after ductal occlusion was > 11.5 years.

CONCLUSIONS AND CLINICAL RELEVANCE

Complete ductal occlusion resulted in immediate removal of the volume overload state and eventual return of cardiac chamber dimensions to reference range, suggesting regression of eccentric hypertrophy. Systolic dysfunction persisted in some dogs but appeared to be clinically unimportant. Most cardiovascular changes were independent of patient age at the time of the procedure.

Long-term outcome in dogs with patent ductus arteriosus: 520 cases (1994-2009)

Background

Published information regarding survival and long‐term cardiac remodeling after patent ductus arteriosus (PDA) closure in dogs is limited.

Objectives

To report outcome and identify prognostic variables in dogs with PDA, and to identify risk factors for persistent remodeling in dogs with a minimum of 12 months of follow‐up after closure.

Animals

Five hundred and twenty client‐owned dogs.

Methods

Retrospective review of medical records of 520 dogs with PDA. Outcome was determined by contacting owners and veterinarians. Dogs with PDA closure and ≥ 12 months of follow‐up were asked to return for a re‐evaluation.

Results

In multivariable analysis of 506 dogs not euthanized at the time of diagnosis, not having a PDA closure procedure negatively affected survival (HzR = 16.9, P < .001). In 444 dogs undergoing successful PDA closure, clinical signs at presentation (HzR = 17, P = .02), concurrent congenital heart disease (HD) (HzR = 4.8, P = .038), and severe mitral regurgitation (MR) documented within 24 hours of closure (HzR = 4.5, P = .028) negatively affected survival. Seventy‐one dogs with ≥ 12 months follow‐up demonstrated a significant reduction in radiographic and echocardiographic measures of heart size (P = 0) and increased incidence of acquired HD (P = .001) at re‐evaluation. Dogs with increased left ventricular size and low fractional shortening at baseline were more likely to have persistent remodeling at re‐evaluation.

Conclusions and Clinical Importance

Patent ductus arteriosus closure confers important survival benefits and results in long‐term reverse remodeling in most dogs. Clinical signs at presentation, concurrent congenital HD, and severe MR negatively affect survival. Increased left ventricular systolic dimensions and systolic dysfunction at baseline correlated significantly with persistent remodeling.

An Intrapericardial Technique for PDA Ligation: Surgical Description and Clinical Outcome in 35 Dogs

A number of surgical techniques have been reported for dissection and ligation of patent ductus arteriosi (PDAs) in dogs. The objectives of this study were to provide a detailed description of an intrapericardial technique for PDA dissection and ligation and to report the clinical outcome of that technique in dogs. Medical records of 35 dogs were retrospectively reviewed for signalment, clinical signs, echocardiographic findings, surgical time, intra- and postoperative complications, and completeness of ductal closure. Median surgery time was 60 min (range, 35–125 min). Neither intraoperative nor postoperative complications occurred. Within 48 hr of surgery, the continuous left basilar heart murmur was absent in all dogs, and complete echocardiographic closure was confirmed in 29 of 32 dogs. Residual flow was identified echocardiographically in three dogs within 48 hr of surgery. Residual flow was decreased in one dog at 1 mo, which resolved within 33 mo. One dog had mild residual flow postoperatively but did not return for follow-up. The intrapericardial technique was successful for PDA dissection and ligation and had a lower rate (6%) of echocardiographic residual flow compared with previously reported techniques.

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.

Patent ductus arteriosus in a family of Chihuahuas

This report describes a patent ductus arteriosus (PDA) in four puppies from the same family of Chihuahuas, bred from the same mother and from two different litters. Identification of this congenital anomaly relies on clinical examination, radiography and ultrasonography. Three of these puppies were female, and had a type-1 PDA. A conventional surgical ligation was performed on one of them, whilst the others underwent no treatment. One puppy was male, and presented with a type-4 PDA, requiring euthanasia. Post-mortem examination and histopathological examination of the PDA allowed characterisation of the histological anomalies, which were identical to those described in other breeds. The mother and the two stud dogs were not affected. Even though the mode of transmission has not been fully identified, it is evident that this PDA is hereditary in nature. To the authors' knowledge this is the first description of this congenital cardiopathy in a family of this breed, and in a significant number of first-generation individuals.

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.

Therapeutic changes of plasma N-terminal pro-brain natriuretic peptide concentrations in 9 dogs with patent ductus arteriosus

The plasma N-terminal proBNP (NT-proBNP) concentration is measured for determining the diagnosis and severity of heart failure in dogs. However, it is still unclear whether measurements of circulating NT-proBNP levels provide clinical utility as an indicator of therapeutic efficacy. Thus, we investigated the surgical correction-related changes of plasma NT-proBNP concentrations in 9 dogs with patent ductus arteriosus (PDA). Physical examination, thoracic radiography and echocardiography were conducted both before and after surgery. Similarly, the plasma NT-proBNP concentrations were determined using an enzyme immunoassay for canine pro-BNP. The International Small Animal Cardiac Health Council (ISACHC) class and murmur grade were significantly improved after surgery compared with before surgery. Vertebral heart size (VHS) and cardiothoracic ratio (CTR) were significantly decreased after surgery. Fractional shortening was significantly decreased and relative wall thickness (RWT) was significantly increased after surgery. Furthermore, the plasma NT-proBNP concentrations were significantly decreased by surgical correction. The plasma NT-proBNP concentration showed significant positive correlation with the ISACHC class, murmur grade, VHS and CTR and significant negative correlation with the RWT. Therefore, measurement of plasma NT-proBNP levels can be used to monitor the effectiveness of therapies such as surgical correction of PDA.