Real-time 3D transesophageal echocardiography-guided closure of a complicated patent ductus arteriosus in a dog

Advanced imaging modalities are becoming more widely available in veterinary cardiology, including the use of transesophageal echocardiography (TEE) during occlusion of patent ductus arteriosus (PDA) in dogs. The dog in this report had a complex history of attempted ligation and a large PDA that initially precluded device placement thereby limiting the options for PDA closure. Following a second thoracotomy and partial ligation, the morphology of the PDA was altered and device occlusion was an option. Angiographic assessment of the PDA was limited by the presence of hemoclips, and the direction of ductal flow related to the change in anatomy following ligature placement. Intra-operative TEE, in particular real-time three-dimensional imaging, was pivotal for assessing the PDA morphology, monitoring during the procedure, selecting the device size, and confirming device placement. The TEE images increased operator confidence that the size and location of the device were appropriate before release despite the unusual position. This report highlights the benefit of intra-operative TEE, in particular real-time three-dimensional imaging, for successful PDA occlusion in a complicated case.     

Role of computed tomography angiography in the differentiation of feline truncus arteriosus communis from pulmonary atresia with ventricular septal defect

Two domestic shorthair cats, a 6-month-old castrated male and a 7-month-old intact female, were diagnosed with complex congenital heart disease. Transthoracic echocardiography in both cats revealed a dilated arterial trunk overriding the interventricular septum with a large ventricular septal defect. The pulmonary trunk and branch pulmonary arteries were not visible using standard echocardiographic views in either cat. The differential diagnosis for both cats included truncus arteriosus communis vs. pulmonary atresia with ventricular septal defect. Each cat underwent computed tomography angiography to determine the origin and extent of the pulmonary blood supply and to better define extra-cardiac anatomy. Computed tomography angiography led to a diagnosis of truncus arteriosus communis with unrestricted pulmonary blood flow in one cat, whereas the other cat was diagnosed with pulmonary atresia with ventricular septal defect and major aortopulmonary collaterals serving as the primary source of pulmonary blood flow. Computed tomography angiography allowed for the ante mortem differentiation of truncus arteriosus communis from pulmonary atresia with ventricular septal defect in these two cats, leading to an accurate diagnosis and providing valuable information to therapeutic decision-making for each case.     

Transvenous detachable coiling of patent ductus arteriosus in small dogs

ObjectiveTo report on transvenous detachable coiling in small dogs deemed ineligible for traditional transarterial patent ductus arteriosus occlusion and compare transthoracic echocardiographic and angiographic measurements to determine their equivalence.Materials and methodsA retrospective study of 35 dogs that underwent transvenous coiling of a patent ductus arteriosus. Demographic information, echocardiographic and angiographic studies, surgery reports, and follow-up evaluation of residual flow were obtained. A Bland-Altman analysis was used to compare echocardiographic and angiographic measurements of the minimal ductal diameter (Echo-MDD, Ang-MDD) and ampulla diameter (Echo-A, Ang-A).ResultsThirty-four of 35 dogs had successful deployment of a coil, with one dog undergoing occlusion with a different device after the exteriorized coil pulled through the ductus. Complete occlusion was achieved in 18 dogs within 24 h; four dogs were lost to follow-up, and the remaining 12 dogs had no residual flow or a significant reduction in shunting with normalization in cardiac chamber dimensions by a median of 99 days. Thirty percent of dogs (11/35) experienced perioperative complications of which 10 were minor complications. The analysis of 26 dogs with both echocardiographic and angiographic ductal measurements showed a −0.14 mm mean difference (95% limits of agreement −1.08 to 0.8 mm) in minimal ductal diameter and −0.68 mm mean difference (95% limits of agreement −2.73 to 1.37 mm) in ampulla diameter.ConclusionsDogs less than 3 kg deemed too small for transarterial occlusion can successfully undergo transvenous coil embolization of patent ductus arteriosus.     

Pulmonary embolization of vascular occlusion coils in dogs with patent ductus arteriosus

Transcatheter coil embolization of patent ductus arteriosus (PDA) was performed in 206 dogs between 1994 and 2003 at Texas A&M University, of which 7 (3%) had embolization of coils to the pulmonary vasculature. Thoracic radiographs indicated that coils were located in the right pulmonary artery in 6 of the 7 dogs. Pulmonary perfusion scans were available for review in 5 dogs, and moderate perfusion defects were observed in the right caudal lung lobe in 4 dogs within 24 hours of embolization. Perfusion deficits observed initially in 2 of the dogs resolved on perfusion scans performed at 6 months and 3.1 years. One dog did not have evidence of focal perfusion defects on a perfusion scan performed 4.5 months after embolization. All pulmonary embolizations occurred during the procedure. Attempts at retrieval of coils were unsuccessful in the 2 dogs in which it was attempted. No short- or long-term clinical complications were observed in any of the dogs with pulmonary embolization. We conclude that pulmonary embolization of vascular occlusion coils is an uncommon event and is not typically associated with adverse clinical effects in dogs with PDA.     

Immediate and late outcomes of transarterial coil occlusion of patent ductus arteriosus in dogs

Records from dogs (n = 125) that underwent attempted transarterial coil occlusion of patent ductus arteriosus (PDA) at the University of California, Davis, between 1998 and 2003, were reviewed, and a subset of these dogs (n = 31) in which the procedure was performed at least 12 months earlier were reexamined to determine long-term outcome. Coil implantation was achieved in 108 dogs (86%). Despite immediate complete ductal closure in only 34% of dogs, the procedure was hemodynamically successful as evidenced by a reduction in indexed left ventricular internal diameter in diastole (LVIDd; P < .0001), fractional shortening (P < .0001), and left atrial to aortic ratio (LA: Ao; P = .022) within 24 hours. Complete ductal closure was documented in 61% of dogs examined 12 to 63 months after coil occlusion. Long-standing residual ductal flow in the other 39% of dogs was not associated with increased indexed LVIDd or LA: Ao and was not hemodynamically relevant. Repeat intervention was deemed advisable in only 4 dogs with persistent (n = 1) or recurrent (n = 3) ductal flow. Complications included aberrant embolization (n = 27), death (n = 3), ductal reopening (n = 3), transient hemoglobinuria (n = 2), hemorrhage (n = 1), aberrant coil placement (n = 1), pulmonary hypertension (n = 1), and skin abscessation (n = 1). Serious infectious complications did not occur despite antibiotic administration to only 40% of these dogs. Transarterial coil occlusion was not possible in 14 dogs (11%) because of coil instability in the PDA and was associated with increased indexed minimum ductal diameter (P = .03), LVIDd (P = .0002), LVIDs (P = 0.001), and congestive left heart failure (P = .03) reflecting a relatively large shunt volume.     

Echocardiographic and angiographic comparison of ductal dimensions in dogs with patent ductus arteriosus

BACKGROUND: Transcatheter occlusion of patent ductus arteriosus (PDA) is a minimally invasive treatment option in dogs. Device selection based on appropriately acquired PDA dimensions and morphology can minimize procedural complications, including minimizing residual ductal flow and inappropriate embolization. HYPOTHESIS: Transesophageal echocardiographic (TEE) derived minimum ductal diameter measurements would most accurately reflect angiographic measurements. Color Doppler (CD) TEE and transthoracic echocardiographic (TTE) ductal measurements would overestimate two-dimensional (2D) measurements. ANIMALS: Fifteen client-owned dogs with PDA. METHODS: PDA dimensions obtained with angiography, 2D and CD TTE, 2D and CD TEE from the right and left views were prospectively evaluated. RESULTS: PDA dimensions were measured by using TEE most closely approximated angiographic measures. CD TTE and TEE frequently overestimated angiographic measures of minimum ductal diameter. TEE accurately identified a type III (tubular) PDA morphology in 1 dog. Fourteen of 15 dogs were determined to have hemodynamically significant reductions in left to right shunting documented by a first-pass nuclear angiocardiographic ratio of pulmonary to systemic blood flow < or = 1.2 and trivial (n = 3) to no (n = 11) CD TTE flow at approximately 1 month after PDA occlusion. CONCLUSIONS: TEE provided accurate anatomic information regarding PDA morphology and closely approximated angiographic ductal dimensions while aiding in both coil deployment and confirmation of intra-operative ductal closure.     

Intracardiac echocardiography: use during transcatheter device closure of a patent ductus arteriosus in a dog

Intracardiac echocardiography (ICE) is used in humans for percutaneous interventional procedures, such as transcatheter device closures. Intracardiac echocardiography provides high-resolution imaging of cardiac structures with two-dimensional, M-mode, Doppler, and also three-dimensional modalities. The present report describes application of ICE during transcatheter occlusion of patent ductus arteriosus using a canine ductal occluder in a dog for which transesophageal echocardiography could not provide an optimal acoustic window.     

Transcatheter closure of patent ductus arteriosus in 11 dogs and one cat after incomplete or aborted surgical ligation

ObjectiveTo describe the characteristics and outcomes of transcatheter patent ductus arteriosus (PDA) occlusion after incomplete or aborted surgical ligation in dogs and cats.AnimalsTwelve client-owned animals (11 dogs and one cat).Materials and methodsThis retrospective study describes data from animals with aborted or incomplete surgical PDA ligation that subsequently underwent transcatheter closure using endovascular methods. Patient demographics, reason for incomplete or aborted surgery, complications, and method of transcatheter occlusion were recorded. Data are presented as mean ± standard deviation or median (interquartile range), where appropriate.ResultsFor all cases, median age at surgery was 12.2 months (4.9–15.1 months) and at catheterization was 15.4 months (8.9–21.9 months), with 79 days (29–209 days) between surgical and interventional procedures. Median weight at catheterization was 4.5 kg (2.5–12.6 kg). Reasons for failed surgical ligation included hemorrhage during ductal dissection in seven dogs, residual flow in four dogs, and inability to identify the ductus in one cat. Transcatheter closure was successfully performed using a canine duct occluder in eight dogs, transarterial coil embolization in two dogs, and transvenous coil embolization in one dog and one cat. Metallic hemoclips partially obscured angiographic findings in three cases with prior surgical hemorrhage but did not prevent transcatheter closure. In all cases, ductal flow was successfully attenuated, with no or trace residual shunting on angiography and complete occlusion the following day on echocardiography.ConclusionsWhen surgery is unsuccessful, either owing to hemorrhage or residual flow, transcatheter closure of PDA is feasible, even in small patients.     

The use of Amplatzer vascular plug II in 32 consecutive dogs for transvenous occlusion of patent ductus arteriosus

ObjectivesTo describe the use of the Amplatzer vascular plug II (AVPII) for transvenous occlusion of patent ductus arteriosus in a non-selective population of dogs, with a focus on the surgical technique, short term outcome and associated complications.Animals, materials and methodsRetrospective study. Records of thirty-two consecutive dogs treated for a left-to-right shunting patent ductus arteriosus with the AVPII were reviewed.ResultsDuctal occlusion with an AVPII occlusion device was attempted in 32 dogs weighing 1.1–53.8 kg. Transvenous occlusion was successful in 30 dogs. One dog required a transarterial approach for occlusion. One dog died during catheterisation of the right heart but prior to transductal catheterisation. Mean ductal ampulla diameter was 7.9 mm (range, 4.1–15.4 mm) and median size of deployed devices was 10 mm (range 4–20 mm). Mean device to ampulla ratio was 1.34 ± 0.15. Device was positioned in situ with no residual flow on follow-up echocardiographic assessment (> one month) in all dogs where deployment was attempted. Occlusion success rate was 96.9% and mortality rate was 3.1%. Four dogs (13.3%) demonstrated minor complications, with none having long-term significance.ConclusionsThe use of AVPII device via a transvenous approach is a feasible and effective method for occlusion of a left-to-right shunting patent ductus arteriosus in dogs of a wide range of weight. The method described may complement existing catheter-based occlusion methods.     

Etiology of patent ductus arteriosus in dogs

Patent ductus arteriosus (PDA) is the most common congenital heart disease in dogs and usually causes heart failure and death unless corrected at a young age. Previous histologic studies in a line of dogs derived from Miniature Poodles with hereditary PDA identified varying degrees of hypoplasia and asymmetry of ductus-specific smooth muscle and the presence of aortalike elastic tissue in the ductus wall sufficient to cause patency. To determine if similar structural abnormalities cause PDA in other dogs, serial-section, 3-dimensional histology of ductal architecture was studied in 8 non-Poodle purebred dogs with PDA with no immediate family history of PDA. Morphologic abnormalities were observed in 7 of 8 dogs with PDA and essentially were the same as those in dogs known to have a hereditary form of PDA. These findings suggest that apparently sporadic PDA in these breeds is caused by a genetic defect in the structure of the ductus arteriosus that is similar or identical to that in the Poodle. The relatives of dogs with PDA, particularly parents, offspring, and siblings, should be screened for evidence of PDA. Dogs with PDA should not be used for breeding, regardless of breed.     

Computed tomography angiography of coarctation of the aorta in a dog

Coarctation of the aorta has been described previously as either a post-mortem or angiographic finding in three dogs with clinical signs related to the aortic coarctation. A 10-year-old dog was presented for evaluation of suspected laryngeal paralysis. On physical examination, femoral pulses were absent bilaterally, with an indirect systolic blood pressure difference of 60 mmHg between the ipsilateral thoracic and pelvic limbs. Coarctation of the aorta was detected on a thoracic computed tomographic angiography study. The coarctation was pre-ductal in position, with extensive dilation of the descending thoracic aorta. Characteristic rib changes that are seen in humans with coarctation were not apparent in this dog. 3D reconstructions of the thorax provided high vascular definition with exact localization of the aortic narrowing.     

Contrast-enhanced magnetic resonance angiography of patent ductus arteriosus in a dog

Gadolinium-enhanced three-dimensional magnetic resonance angiography is a relatively new technique in the veterinary field. A mature dog with suspected patent ductus arteriosus underwent contrast-enhanced magnetic resonance angiography at 1·0 T with a three-dimensional fast low-angle shot (FLASH) gradient-echo technique. Qualitatively, three-dimensional images of the ductus were particularly clear with surface reconstructions, and ductus diameters were easy to assess in native images. Contrast-enhanced magnetic resonance angiography is a fast, relatively non-invasive procedure that could be particularly useful when non-surgical interventional procedures are anticipated for ductus occlusion.     

Transvenous embolization of small patent ductus arteriosus with single detachable coils in dogs

Transvenous embolization of small patent ductus arteriosus (PDA; < or = 4 mm) with a single detachable coil was attempted in 24 dogs (median age 5.7 months, range, 2.6-65.5 months; median body weight 5.5 kg, range, 1.5-30.0 kg). Angiographic imaging of the duct and pressure measurements were made before and after embolization. The minimal ductal diameter was 2.7 +/- 0.7 mm. In all dogs, a single coil was employed regardless of residual shunting. Ten dogs (PDA minimal diameter range, 1.5-2.2 mm) received a 5-mm coil, and 14 dogs (PDA minimal diameter range, 2.9-3.6 mm) received a 8-mm coil. After coil embolization the angiographic shunt grade decreased significantly (n = 20, P < .001). Residual shunts were assessed by angiography 15 minutes after and by Doppler echocardiography 1-3 days and 3 months after the intervention. In the dogs treated with the 5-mm coils the residual shunt rate was low (0%, 10%, and 0% for angiography and Doppler echocardiography at 1-3 days and 3 months, respectively), in contrast to the dogs treated with the 8-mm coils (91%, 79%, and 67% for angiography and Doppler echocardiography at 1-3 days and 3 months, respectively). After 3 months, no residual murmur was found in dogs treated with the 5-mm coils (0/7), in contrast to murmurs in 5 of 12 (42%) dogs treated with the 8-mm coils. Despite incomplete closure in these dogs, volume loading of the left heart decreased in all dogs. Pulmonic or aortic coil embolism did not occur. Analysis of initial results shows that single detachable coil embolization is possible in all dogs with a small PDA (< or = 4 mm), but only very small PDA (< or = 2.5) could be treated effectively, and for the moderate PDA (2.6-4.0 mm) longer coils or multiple coils may be necessary to achieve complete occlusion.     

Use of transesophageal echocardiography for visualization of the patent ductus arteriosus during transcatheter coil embolization

Transesophageal echocardiography (TEE) enhances our ability to see the patent ductus arteriosus in the dog. The improved visualization may potentially improve our ability to perform transcatheter coil embolization in patients that are more likely to have a successful outcome. This report uses still and video images to detail the specifics of coil embolization as performed with the assistance of TEE and compares the images with those of angiography, surgery and postmortem examination.     

Acute onset of pulmonary necrotising arteritis in a dog with a left-to-right patent ductus arteriosus

A 12-week-old, clinically normal Chihuahua was referred for investigation for a continuous heart murmur. Cardiac evaluation revealed an anatomically and haemodynamically typical left-to-right shunting patent ductus arteriosus. The continuous wave Doppler measurement of peak ductal jet velocity of 5.6 m/s was suggestive of a normal pulmonary to systemic arterial pressure ratio. The dog returned 16 days later with right heart failure and severe pulmonary hypertension. Marked reduction in left-to-right shunting was demonstrated and the ductal jet velocity had decreased to 2.5 m/s. Immediate ductus ligation, oxygen therapy before and after the operation, and administration of hydralazine failed to reduce pulmonary hypertension, and the dog was euthanased. Histopathological examination of the lung showed pulmonary necrotising arteritis with acute and chronic arterial lesions. Chronic pulmonary vascular changes related to high flow have been associated with altered nitric oxide and endothelin responses. These changes may be responsible for the acute onset of pulmonary hypertension due to relatively minor vascular insults in some human and veterinary patients with left-to-right shunts. The potential for acute progression supports the recommendations for early ductus ligation and the prognostic importance of detecting pulmonary hypertension presurgically in patent ductus arteriosus patients.     

Long-term clinical management of right-to-left ("reversed") patent ductus arteriosus in 3 dogs

A small number of dogs with patent ductus arteriosus (PDA) have right-to-left flow of blood through the ductus, leading to polycythemia and clinical signs associated with hyperviscosity. Three dogs with right-to-left-shunting PDA are described. Treatment consisted solely of phlebotomy, performed on an outpatient basis when indicated by exacerbation of clinical signs, for a total of 11-68 times on each dog. Each treatment entailed the removal of a mean of 19% (maximum 28%) of circulating blood volume, divided into 2 phlebotomies several hours apart, without intravenous fluid replacement. Subjectively, marked clinical improvement was noted. Intermittent clinical signs decreased in frequency and severity in all dogs. Adverse effects were rare (1 for 98 phlebotomies) and reversible. Dogs lived > 2 to > 8 years during treatment. Outpatient phlebotomy without fluid replacement was safe, and was associated with subjective improvement and prolonged survival in these dogs.     

Utility of N-terminal pro-brain natriuretic peptide for assessing hemodynamic significance of patent ductus arteriosus in dogs undergoing ductal repair

ObjectiveDetermine if plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) correlates with markers of hemodynamically significant patent ductus arteriosus (PDA) in dogs.AnimalsTen dogs with PDA and 30 healthy dogs of similar ages.MethodsProspective case series with control population. Dogs with PDA were initially evaluated with thoracic radiographs, transthoracic echocardiography, pulmonary capillary wedge pressure (PCWP) and NT-proBNP. Following ductal occlusion, NT-proBNP and echocardiography were repeated within 24 h and at day 90. PCWP was repeated at day 90. Correlation between NT-proBNP and hemodynamic measurements was assessed, and accuracy of NT-proBNP for identifying PDA severity was estimated.ResultsNT-proBNP was significantly higher (median; absolute range) in dogs with PDA (895; 490–7118 pmol/L) than controls (663; 50–1318 pmol/L) (p = 0.025). NT-proBNP decreased significantly 90 days post-ductal closure (597; 154–1858 pmol/L) (p = 0.013). Left atrial and ventricular size decreased significantly within 24 h and at day 90 as did PCWP (day 90 only). NT-proBNP correlated with vertebral heart size (VHS) and indexed left ventricular systolic diameter (iLVIDs); concentrations ≥ 1224 pmol/L distinguished dogs with elevated VHS and iLVIDs.ConclusionsNT-proBNP is elevated in dogs with PDA, decreases following PDA closure and correlates with select radiographic and echocardiographic markers of cardiac remodeling.     

Double-chambered left ventricle in a cat

Double-chambered left ventricle is a rare congenital disorder in which the left ventricular cavity is subdivided into two cavities by an anomalous septum or muscle band. We describe a case of double-chambered left ventricle, most likely caused by the presence of excessive left ventricular bands, in an asymptomatic cat.