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.     

Closure of large patent ductus arteriosus with a self-expanding duct occluder in two dogs

Of the different catheterisation methods described for closure of patent ductus arteriosus (PDA), coil embolisation is most commonly used in dogs. However, for a PDA larger than 4 to 5 mm in diameter, coil implantation is difficult. For these cases, the Amplatzer duct occluder (ADO) offers an alternative method. This report describes the successful implantation of an ADO in two dogs with large PDAs of approximately 6 mm diameter. The self-expandible device attached to an implantation wire was advanced through a long sheath antegrade to the femoral vein through the right heart and pulmonary artery to the duct and delivered into the PDA. Thereafter the device was released by unscrewing it from the delivery cable. The large PDA in both dogs was totally occluded by these means without any residual shunt. Thus, the ADO is a controlled release implant that also allows occlusion of a large PDA. Its high costs limit its general use in veterinary medicine at the present time.     

Congenital cardiac diseases in dogs: a retrospective analysis

In a time period of 6 years, 158 congenital cardiac defects were diagnosed in 146 dogs at the Clinic for Small Animal Medicine University of Zurich. In respect to all dogs with cardiac disease, these were 23.5% of the cases. Most common defects were subaortic stenosis (SAS, 31.5%), pulmonic stenosis (PS, 23.3%), ventricular septal defect (VSD, 14.4%), patent ductus arteriosus (PDA, 13.7%) and tricuspid dysplasia (TD, 7.5%). Complex defects were found in 8.2% of the dogs. Although single dogs per breed were affected by various defects, some breed-related tendencies could be observed. We found PS more numerously in boxers and Jack Russell Terriers whereas SAS, VSD and TD were also found in breeds reported to be predisposed. Congenital cardiac defects are an important clinical entity, and knowledge of prevalence is helpful when considering the differential diagnosis and for making a tentative diagnosis in an individual case.     

Treatment of patent ductus arteriosus by placement of two intravascular embolisation coils in a puppy

A 14-week-old border collie with a history of exercise intolerance was confirmed to have a patent ductus arteriosus (PDA) from colour flow Doppler echocardiography. Under general anaesthesia, angiography was performed to gauge accurately the width of the ductus, and then two intravascular embolisation coils were introduced into the ductus via percutaneous catheterisation of the femoral vein. The coils were both 8 mm in diameter, each with four loops. This led to an immediate disappearance of the murmur. Some slight residual flow was detected at the time of the procedure by angiography, but by 10 days postoperatively there was no PDA flow detectable. The time taken to complete the procedure was 55 minutes, with a total fluoroscopy time of 15 minutes. Placement of intravascular embolisation coils represents a viable alternative to traditional surgical methods of ductus closure.     

Interventional Closure of a Patent Ductus Arteriosus Using an Amplatz Canine Duct Occluder in an Alpaca Cria

A 6‐month old female alpaca cria presented to The Ohio State University for evaluation of a cardiac murmur. Echocardiography revealed a left‐to‐right shunting patent ductus arteriosus, a restrictive left‐to‐right shunting perimembranous ventricular septal defect, and secondary moderate left atrial and ventricular dilation. Aortic root angiography demonstrated a type IIA patent ductus arteriosus (PDA). Interventional closure of the PDA was successfully performed, without complication, using an Amplatz canine duct occluder. This case report describes the materials and methods used for interventional closure of a PDA in an alpaca cria.     

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).     

Patent ductus arteriosus repair in general practice

A 3-month-old female German Shepherd puppy was presented for routine vaccination. Clinical evaluation revealed a grade 5/6 continuous murmur with the point of maximal intensity over the left 4th intercostal space. Echocardiography revealed a patent ductus arteriosus (PDA). The PDA was closed by a team of general practitioners using the Jackson-Henderson technique, via a standard 4th intercostal thoracotomy. A multi-modal approach to analgesia and premedication was employed. A successful outcome was achieved with no murmur or evidence of cardiac disease present 6 months after surgical occlusion. The literature is reviewed with an emphasis placed on choosing techniques that are appropriate to the level of expertise of the surgical and anaesthetic teams, as well as the surgical facilities available.     

Detachable Coils for Occlusion of Patent Ductus Arteriosus in 2 Dogs

OBJECTIVE: To describe the use of a detachable coil for transcatheter closure (TCC) of patent ductus arteriosus (PDA) in 2 dogs. STUDY DESIGN: Clinical study. ANIMALS: Two female Pembroke Welsh Corgi dogs with PDA. METHODS: Using fluoroscopic guidance, an 8-mm-diameter coil stent with 5 loops (detachable coils for PDA closure) was inserted via catheterization of the femoral artery. The catheter was passed through the PDA into the pulmonary artery. The coil was withdrawn so that 1.5 loops remained on the pulmonary side of the orifice of the ductus. The rest of the loops were pushed out from the catheter into the ductus. After confirming the correct placement of the coil and the effectiveness of the occlusion, the delivery wire was detached from the coil. RESULTS: Insertion of the coil was easily performed, even without previous experience. Immediate and marked decrease of the cardiac murmur was auscultated. Only slight residual flow was detected by angiography conducted 3 months' postoperatively. The dogs experienced quick and uneventful recovery after coil placement and required minimal postoperative care. Follow-up evaluation of the dogs showed no functional clinical signs of PDA, and no cardiac abnormalities were detected on electrocardiographic, phonocardiographic, and echocardiographic examination. In dog 1, the residual flow had disappeared on the color-flow Doppler echocardiographic examination at 18 months' postoperatively. CONCLUSION: TCC using a detachable coil was easy, safe, and effective in 2 dogs with PDA. The minimal residual shunting observed only by echocardiography seemed hemodynamically insignificant. CLINICAL RELEVANCE: This method can be used as an alternative to traditional surgical methods.     

Necrotizing pulmonary arteritis in a dog with patent ductus arteriosus

A 4-month-old, male Cocker Spaniel was examined because of exercise intolerance. A grade IV/V holosystolic diastolic murmur was auscultated. Increased pulmonary arterial pressure was measured via cardiac catheterization. A patent ductus arteriosus (PDA) was diagnosed radio-graphically by injection of contrast media into the sinus of Valsalva with the immediate appearance of contrast in the pulmonary artery. The dog was destroyed at the owner's request. The presence of a PDA was confirmed by necropsy examination. Medial hypertrophy and necrotizing arteritis of muscular pulmonary arteries were observed on histopathologic examination.     

Congenital cardiac disease in dogs

Patent ductus arteriosus (PDA) is thought to be inherited and occurs twice as often in females as in males, most commonly in Poodles, Collies, Cocker Spaniels and Shetland Sheepdogs. About half of untreated dogs develop left-sided heart failure by 8 months of age. Clinical signs include coughing, decreased exercise tolerance, pulmonary edema, a "machinery" murmur in the pulmonic-aortic region, and a bounding pulse. An ECG may reveal an increased amplitude of the R wave and a lengthened P wave. Plain LAT films reveal loss of the cranial and caudal cardiac waists, increased sternal contact of the heart, increased width and straightened caudal border of the cardiac silhouette, elevated carina, and an enlarged left atrium. Changes on plain DV films include an elongated cardiac silhouette, enlarged right ventricle, and 3 bulges on the left side of the cardiac silhouette. Nonselective angiocardiography can be used for a definitive diagnosis and to demonstrate a reverse right-to-left PDA, in which the ascending aorta, brachiocephalic trunk and left subclavian artery are not opacified by contrast medium. Animals with a right-to-left shunt PDA are cyanotic in caudal body parts. Treatment of left-to-right shunt PDA involves ligation with 2 nonabsorbable sutures. A right-to-left shunt PDA should not be ligated but is treated by restricted exercise and periodic phlebotomy.     

The relevance of echocardiography heart measures for breeding against the risk of subaortic and pulmonic stenosis in Boxer dogs

The aims of this study were to investigate the role and relative importance of auscultation and echocardiography traits as risk factors for the diagnosis of subaortic (SubAS) and pulmonic (PS) stenosis and to estimate the heritability (h(2)) of cardiac measurements taken through echocardiography for a random sample of Italian Boxer dogs. The data were cardiovascular examination results of 1,283 Italian Boxer dogs (686 females and 597 males) enrolled in the national screening program for heart defects arranged by the Italian Boxer Club. Examinations were performed during a 6-yr period by a group of 7 veterinary cardiologists following a standard protocol. Occurrence and severity of SubAS and PS were diagnosed, taking into account clinical and echocardiography findings such as the grade of cardiac murmur, direct ultrasound imaging of the anatomic obstructive lesions, and values of aortic or pulmonary blood flow velocities. A Bayesian logistic regression analysis was performed to identify clinical and echocardiography variables related to SubAS and PS diagnosis. Estimation of variance components for clinical and echocardiography traits was performed using a mixed linear animal model, Bayesian procedures, and the Gibbs sampler. Prevalence of SubAS (PS) was 8.4% (2.2) and 10.7% (6.4) for female and male dogs, respectively. Cardiac murmur, peak velocities, and annulus areas behaved as risk factors for SubAS and PS. The risk of a positive diagnosis for SubAS was 3 times greater for dogs with aortic annulus area <2.1 cm(2) relative to dogs with areas >2.37 cm(2), 84 times greater for dogs showing aortic peak velocities >2.19 m/s relative to dogs with peak velocities <1.97 m/s, and 41 times greater for dogs with moderate to severe murmur grades relative to dogs with absent murmur. Similar results were obtained for PS. The estimated h(2) for the occurrence of cardiac defects was 23.3% for SubAS and 8.6% for PS. Echocardiography and cardiac murmur grades exhibited moderate h(2) estimates and exploitable additive genetic variation. The estimated h(2) was 36, 24, and 20% for aortic annulus area, aortic peak velocity, and cardiac murmur score, respectively. For the area of the pulmonary annulus and peak pulmonary velocity, the estimated h(2) were smaller, ranging from 9.5 to 12.8%. These measures are candidate indicator traits that might be effectively used in dog breeding to reduce the prevalence and severity of cardiac defects.     

Infective endocarditis of the aortic valve in a Border collie dog with patent ductus arteriosus

Infective endocarditis (IE) in dogs with cardiac shunts has not been reported previously. However, we encountered a dog with concurrent patent ductus arteriosus (PDA) and IE. The dog was a 1-year-old, 13.9-kg female Border collie and presented with anorexia, weight loss, pyrexia (40.4°C) and lameness. A continuous murmur with maximal intensity over the left heart base (Levine 5/6) was detected on auscultation. Echocardiography revealed a PDA and severe aortic stenosis (AS) caused by aortic-valve vegetative lesions. Corynebacterium spp. and Bacillus subtilis were isolated from blood cultures. The dog responded to aggressive antibiotic therapy, and the PDA was subsequently surgically corrected. After a series of treatments, the dog showed long-term improvement in clinical status.     

Transvenous correction of patent ductus arteriosus in two toy-breed dogs with the Amplatzer™ Vascular Plug 4

Two Pomeranian dogs referred for interventional correction of a left-to-right shunting patent ductus arteriosus (PDA) had inadequate femoral arterial access for any occlusion device other than micro coils. The decision was made to attempt correction of the PDA using the Amplatzer™ Vascular Plug 4 (AVP4) from a femoral venous approach. An AVP4 was successfully deployed in each dog with complete occlusion noted within 5 min. Complete occlusion was persistent at 24 h after the procedure, while both dogs were subclinical, had no residual ductal flow, and complete or near complete reverse cardiac remodeling at subsequent visits. This report demonstrates the feasibility of PDA occlusion with the AVP4 from the femoral venous approach in small dogs where femoral arterial access is inadequate for other occlusion devices.     

Urinary catheterisation of female dogs: a comparison between three techniques for catheter placement

The objective of this study was to describe a new technique for urinary catheterisation of female dogs using a novel catheterisation device (NCD) and to compare the time taken to place a catheter using this technique with traditional techniques. A secondary objective was to survey participants on which of the techniques they preferred. Female canine cadavers of varying sizes were utilised and veterinary students who had not previously placed a urinary catheter were enrolled. Each participant performed three catheterisation techniques, Visual with speculum (SPEC), Blind Palpation (BP) and catheterisation with NCD on three sizes of dog. Time required using each technique was compared using Kaplan–Meier plots and mixed models Cox Proportional Hazards regression. Median times to catheterisation were 300 s (IQR 261–417 s) with the SPEC method, 420 s (IQR 253–545 s) with the NCD method and 725 s (574–1032s) with the BP method. Both SPEC and NCD methods were significantly faster compared to the BP method, with Hazard Ratios of 3.66 (95% CI 1.94–6.91, P < 0.001) and 3.57 (95% CI 1.87–6.81, P < 0.001), respectively. Six of nine participants found the NCD the easiest technique, 5/9 of the participants found the palpation technique most difficult and 4/9 found the speculum technique most difficult. BP appears to be the technique of least preference and increased time requirement. The novel urinary catheterisation device may provide a simpler method of visualisation of the urethral papilla and may provide a more sterile way of placing the catheter, although further investigation is needed to confirm this.     

Invasive pressure measuring for the determination of the aortic opening surface in normal and stenotic left ventricular outflow tracts

A method of evaluation of the aortic opening area in healthy dogs and dogs with aortic stenosis is described. Through right and left heart catheterisation intraventricular and intravascular pressures were measured. For the determination of cardiac output the thermodilution technique is used. The aortic opening area is calculated by using the GORLIN-formula. Values of normal and stenotic left ventricular outflow opening area are given.     

Diagnostic value of contrast echocardiography in the horse

M-mode echocardiography is a safe and practical means of using ultrasound to evaluate the dynamic movements of cardiac structures. The technique can be refined by using a simple contrast medium in the form of carbon dioxide mixed with heparinised blood to provide a strong echogenic result. This technique was employed in a series of 15 normal conscious standing horses and in three animals with specific cardiac defects. In the clinical cases it was possible to confirm the diagnosis and differentiate between a congenital septal defect and mitral regurgitation. The method was found to be safe and relatively simple to perform using percutaneous insertion of catheters. The intracardiac catheterisation was trouble free and no clinical side effects to direct injection of the carbon dioxide contrast medium into the heart were demonstrated.     

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.     

Peri-operative changes in echocardiographic measurements and plasma atrial and brain natriuretic peptide concentrations in 3 dogs with patent ductus arteriosus

Peri-operative changes in echocardiographic measurements and plasma levels of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) were investigated for 1 month in 3 dogs with patent ductus arteriosus (PDA). Post-operative left ventricular end-diastolic dimention and fractional shortening decreased in all cases. Pre-operatively increased plasma ANP concentrations reduced dramatically after the operation. Peri-operative changes in plasma BNP levels had slightly S-shaped curves in all cases. These observations suggest that post-operative responsiveness of ANP and cardiac function are rapid in comparison with cardiac morphological changes, and BNP has a different pathophysiological significance from ANP in dogs with PDA.     

Postoperative rupture of an aortic aneurysmal dilation associated with a patent ductus arteriosus in a dog

OBJECTIVE: To describe an unusual case of fatal aortic aneurysm rupture after standard ligation of a left-to-right shunting patent ductus arteriosus (PDA) and review the literature concerning the causes of aneurysm and applicable medical physics of blood flow that may contribute to mural failure. STUDY DESIGN: Clinical case report. SAMPLE POPULATION: An 11-month-old female Brittany spaniel. RESULTS: A PDA was diagnosed in the dog after referral for a grade IV/IV cardiac murmur. Diagnostic tests performed included a minimum database, thoracic radiography, and echocardiography. Conventional surgical ligation of the PDA was performed. The postoperative recovery from anesthesia was uneventful. Approximately 5 hours after surgery, the dog vocalized once and collapsed. All resuscitative efforts failed. Necropsy showed a large, spiral rupture of the cranial and dorsal wall of the aorta that extended from the left subclavian artery to 2 cm distal to the PDA-aorta junction. No evidence of intramural, perianeurysmal hemorrhage or inflammation was noted. Histopathologic examination of the ruptured aneurysm showed that the wall lacked a defined tunica intima and endothelial cell layer. A distinct separation of the thinned tunica media parallel to the elastic fibers was noted. CONCLUSIONS AND CLINICAL RELEVANCE: Dilatation of the aorta near the area of a PDA is one of the recognized abnormalities associated with the condition. Aneurysmal dilatation results from and contributes to abnormal blood flow dynamics and increased aortic wall tension, which promotes expansion. Although an unusual and previously unreported sequela, rupture of the aneurysm should be considered a possible complication when ligation of a PDA with a conspicuous aortic aneurysmal dilation is performed.     

Aberrant branch of the bronchoesophageal artery resembling patent ductus arteriosus in a dog

An anomalous shunt between the bronchoesophageal artery and pulmonary artery was diagnosed in a 1-year- old, 3.5 kg female Miniature Dachshund by selective contrast angiography. A cardiac murmur had been observed in the dog during examination at another hospital. The machinery murmur was auscultated at the left side of the base of the heart. Although thoracic radiography revealed mild cardiomegaly, the characteristic findings of patent ductus arteriosus (PDA), including as aortic arch enlargement and pulmonary artery enlargement were not observed. Echocardiography demonstrated shunting of blood flow presumably from the arterial duct at the pulmonary artery carina. Based on the above findings the case was diagnosed as PDA. Angiocardiography was performed to confirm the diagnosis in preparation for surgical treatment, but later we confirmed that the shunt vessel was not PDA, but apparently a branch of the bronchoesophageal artery. The shunt vessel was branching in a complicated manner and shunted to the pulmonary artery.