Development of three-dimensional cardiac models from computed tomography angiography.

Three-dimensional (3D) modeling and printing is an emerging technology in veterinary cardiovascular medicine allowing the fabrication of anatomically correct patient-specific models. These patient-specific models can be used for a wide range of purposes including medical teaching, assessment of cardiac function and movement of valve leaflets, design and assessment of devices created for interventional procedures, and pre-surgical planning [1-3]. Additionally, these 3D models can facilitate communication between the clinical team and the patient's owner. The process of creating 3D models starts with acquiring volumetric imaging data sets of the area of interest. Three-dimensional modeling and printing are reliable when high-quality volumetric imaging data are used to create these models. Currently, only ungated- and electrocardiogram (ECG)-gated computed tomography (CT), cardiac magnetic resonance imaging (CMRI), and 3D echocardiography provide the volumetric data sets needed to create these 3D models. These imaging data sets are imported into a software or open-source freeware platform and then segmented to create a virtual 3D model. This virtual 3D model can be further refined using computer-aided design (CAD) software and then be printed to create a physical 3D model. Cardiovascular 3D modeling and printing is a new medical tool which allows us to expand the way we plan interventional procedures, practice interventional skills, communicate with the medical team and owner, and teach future veterinarians.

Echocardiographic and electrocardiographic effects of atenolol versus sotalol in dogs with severe subaortic stenosis.

BACKGROUND: Subaortic stenosis (SAS) is a commonly diagnosed canine congenital cardiac defect, with severe forms of carrying a poor long-term prognosis. To date, an effective treatment strategy has not been developed in veterinary medicine. This study sought to determine if sotalol, a class III antiarrhythmic, may have salient echocardiographic and antiarrhythmic benefits for medical management for dogs affected with severe SAS. METHODS: Ten dogs diagnosed with severe SAS were enrolled in this prospective, double-blinded, crossover study. Dogs underwent physical exam, non-invasive blood pressure measurement, electrocardiography, echocardiography, and 24-h Holter monitoring. Diagnostics were repeated 12-16 days following randomization to oral atenolol (0.5-1 mg/kg) or sotalol (1-2 mg/kg) twice daily. After a medication taper and four-day washout, dogs were crossed-over to the alternate study medication, and the diagnostics were repeated in 12-16 days. Linear and multinomial mixed models were developed to evaluate the effects of treatments on echocardiographic and electrocardiographic variables. RESULTS: Indices of left ventricular systolic function were reduced based on the volumetric assessment when dogs received sotalol compared to atenolol. No difference was noted between groups in left ventricular systolic function based on the linear assessment. No difference was observed in the reduction in left ventricular outflow tract velocity. No significant differences were observed between treatment groups for any variable on 24-h Holter monitor. CONCLUSIONS: Sotalol may be a viable therapy to consider for dogs with severe SAS based on this pilot study. A larger, prospective study is necessary to investigate further.

Epicardial pacemaker implantation and outcome in eight pet ferrets (Mustela putorius furo).

INTRODUCTION/OBJECTIVES: Minimal information exists regarding epicardial pacemaker (EP) implantation in pet ferrets (Mustela putorius furo). The objectives were to describe the indications, surgical technique, and outcome of EP implantation in ferrets for the treatment of advanced atrioventricular block (AVB). ANIMALS, MATERIALS, AND METHODS: Eight client-owned ferrets presenting to five veterinary referral centers. Signalment, physical exam findings, diagnostic tests, anesthesia protocols, surgical implantation techniques, postoperative treatment plans, and EP interrogations were reviewed. Intra- and postoperative, minor and major, and EP-related complications were established. Descriptive statistics were performed to report complication rates. Survival analyses were performed. RESULTS: All ferrets had advanced AVB: 3/8 had high-grade second-degree and 5/8 had third-degree. The primary clinical signs were collapse and weakness. Seven EP were implanted via a transdiaphragmatic approach and one via a left intercostal thoracotomy. Intraoperative complications occurred in 2/8 ferrets, both major. One ferret with severe comorbidities died during general anesthesia. Postoperative pacemaker-related complications were minor: inappropriate sinus beat sensing in 2/8 and occasional muscle fasciculations in 1/8. Two ferrets were alive at the time of manuscript submission, at 10 and 21 months postoperatively. The overall median survival time was 24 months. CONCLUSIONS: Implantation of EP was performed successfully in most ferrets for treatment of advanced AVB and was well tolerated. Ferrets with advanced AVB may experience resolution of clinical signs associated with their cardiac disease following EP implantation. Additional studies are warranted to investigate the effects of epicardial pacing on survival times in this species.

Single left coronary ostium with a prepulmonic right coronary artery course in a French Bulldog with congenital valvular pulmonary stenosis.

A two-year-old, male castrated, French bulldog was presented for evaluation of coronary artery anatomy before balloon valvuloplasty for severe pulmonic valve stenosis. Multidetector computed tomography angiography showed a single left coronary ostium, absent right coronary ostium, and an anomalous, prepulmonic coursing right coronary artery. Medical management was elected to avoid the attendant risk associated with intervention. This case report documented the first known case of this specific anomaly in French bulldogs. Veterinary cardiologists should be aware of the potential for this specific coronary artery anomaly in this breed, given the predilection for the development of pulmonary stenosis. Routine screening of French bulldogs for anomalous, prepulmonic coronary arteries is recommended before interventional balloon valvuloplasty.

Evaluation of the NuCLEUS-X™ balloon valvuloplasty catheter for severe pulmonic stenosis in dogs.

INTRODUCTION/OBJECTIVES: Balloon instability is commonly encountered during balloon pulmonary valvuloplasty (BPV) and may result in an unsuccessful procedure. The NuCLEUS-X™ catheter is a recently developed BPV catheter with a unique barbell shape and an ordered pattern of inflation that stabilizes the balloon to span the valve annulus before expansion of the balloon center. ANIMALS: Ten client-owned dogs with severe valvular pulmonic stenosis (PS). MATERIALS AND METHODS: Prospective observational study. The BPV procedure was performed by standard technique with use of NuCLEUS-X™ catheters targeting a balloon-to-annulus ratio between 1.2 and 1.5. Balloon stability, safety, and procedural success were assessed. Procedural success was defined as either a reduction in the Doppler transpulmonic PG by at least 50% of the pre-procedural PG or <80 mmHg one month post procedure. RESULTS: Balloon stability centered at the pulmonic valve on the first inflation was achieved in 10/10 cases. The mean PG before BPV was 141 mmHg ±41 mmHg, and the PG after BPV at one month was 83 mmHg ±41 mmHg. Procedural success was achieved in 56% of patients. All dogs survived the BPV, and no major procedural complications were encountered using the NuCLEUS-X™ catheter. CONCLUSIONS: The use of the NuCLEUS-X™ catheter is feasible for BPV in dogs with severe PS. The unique balloon shape provided catheter stability on the first inflation in all dogs, which may be beneficial when stabilization of a conventional BPV catheter cannot be achieved.

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

INTRODUCTION/OBJECTIVES: Coronary artery abnormalities are described sporadically in dogs, most commonly with pulmonic stenosis. Computed tomographic angiography (CTA) allows non-invasive assessment of coronary anatomy. Three-dimensional (3D) models improve the understanding and visualization of spatially complex anatomy. The study objective was to evaluate coronary artery anomalies using CTA imaging and using rapid prototyping technology to create life-sized coronary artery models of these studies. ANIMALS, MATERIAL AND METHODS: Combined retrospective case and prospective pilot study. Inclusion criteria were dogs with reported coronary artery anomalies. The CTA data sets were imported into a medical imaging framework for the analysis of the coronary arteries and into a 3D-planning and printing software for creating printable 3D models. The 3D models were printed using fusion deposition modeling technology. RESULTS: Six male dogs with an R2A coronary artery anomaly and pulmonic stenosis diagnosed by CTA were included. Electrocardiogram (ECG)-gated CTA allowed better identification of anomalous coronary arteries than non-gated CTA. In all dogs, the right coronary artery had a smaller diameter than the left and the left coronary artery or its branch had a prepulmonic course. All ECG-gated studies were 3D printed while non-gated studies were not printable due to CTA artifacts. CONCLUSION: In dogs, CTA is effective for diagnosis of coronary artery anomalies. Printed 3D models of ECG-gated CTA studies were of excellent quality and allowed direct visualization of abnormal coronary artery anatomy. The usefulness of these models to improve the understanding of anomalous coronary artery anatomy could be evaluated in future studies.

Inotropic and chronotropic effects of sotalol in healthy dogs.

INTRODUCTION: Sotalol is an anti-arrhythmic drug commonly used for the treatment of pathologic tachyarrhythmias in dogs. The ß-adrenergic blockade associated with sotalol administration may result in reduced myocardial contractility, which is clinically relevant for treating dogs with arrhythmias and concurrent myocardial dysfunction. The inotropic properties of sotalol are not well characterized in dogs. ANIMALS, MATERIALS, AND METHODS: Ten healthy, adult, large breed dogs were prospectively enrolled. All dogs underwent physical examination, blood pressure measurement, electrocardiography, 24-h Holter monitoring, and echocardiography including three-dimensional left ventricular volume measurements. Dogs were subsequently administered sotalol (1-2 mg/kg) orally twice daily for 12-16 days, and the same diagnostic tests were performed. Paired statistical analysis was used to compare parameters at baseline and after treatment with sotalol. RESULTS: Standard echocardiographic parameters of systolic function were reduced on sotalol compared to baseline, including ejection fraction via Simpson's method of disks which was 5.8% (95% confidence interval [CI]: 2.77-8.83%, p = 0.002) lower post-treatment. Maximum heart rate on Holter monitor was 17 bpm (95% CI: 9-37 bpm, p = 0.002) lower post-treatment than at baseline. CONCLUSIONS: Sotalol has a mild negative inotropic effect in healthy dogs based on standard echocardiographic measurements. There is also a negative chronotropic effect at higher heart rates based on 24-h Holter monitoring.

Left atrial size and volume in cats with primary cardiomyopathy with and without congestive heart failure.

INTRODUCTION/OBJECTIVES: Myocardial diseases are the most common acquired cardiac diseases in cats and may result in left atrial enlargement and congestive heart failure (CHF). Volume calculations have replaced linear measurements for chamber quantification in humans but are not commonly measured in cats. The aims of this retrospective study were to compare the left atrial (LA) size by two-dimensional linear measurements to two-dimensional LA volumes (LAV). ANIMALS: One hundred sixty-two client-owned cats were included. MATERIALS AND METHODS: Cats with complete echocardiographic examinations were included and categorized into one of the three groups: healthy, cardiomyopathy (CM), and CHF. Seven measurements of the LA size were performed including minimal and maximal LA-to-aortic ratio (LA:Ao) and LAV and also maximal left atrial diameter (LAD). RESULTS: Cats were classified as healthy (n = 56), CM (n = 62), and CHF (n = 44). The minimal LA:Ao (LA:Aomin) and minimal LAV from the left apical view (LAVmin-LAP) best differentiated the CM and CHF groups. The LA:Aomin value with the optimal sensitivity and specificity to distinguish CM and CHF cats was 1.64 (sensitivity 84% and specificity 75%). CONCLUSIONS: Left atrial volumes were not superior to linear measurements of LA size in distinguishing CM and CHF cats in this study. Minimal LA size and volumes resulted in a larger area under the curve than each corresponding maximal value. Minimum LA size may be a better prognostic factor of CHF in cats with CM.

Prevalence of major complications and procedural mortality in 336 dogs undergoing interventional cardiology procedures in a single academic center.

INTRODUCTION: Overall complication rates associated with a wide range of diagnostic and therapeutic interventional cardiac procedures in a contemporary academic setting have not been reported. ANIMALS, MATERIALS AND METHODS: Consecutive interventional procedures performed for client-owned dogs were retrospectively analyzed to characterize procedural complications and mortality. RESULTS: Three hundred sixty-four procedures were performed on 336 dogs. Interventions included attempted or completed transvenous pacemaker (PM) implantation (n = 134) with subsequent pacing system revision (n = 8), pulmonic balloon valvuloplasty (BVP) (n = 117) with a subset of patients undergoing an additional BVP (n = 14), transarterial closure of left-to-right shunting patent ductus arteriosus (PDA) (n = 66), diagnostic angiography and/or cardiovascular pressure measurement (n = 9), transvenous temporary pacing (n = 7), septal defect occlusion (n = 5), heartworm extraction (n = 3), and BVP catheter fragment retrieval (n = 1). The prevalence of major perioperative and postoperative complications for all procedures was 5% and 6%, respectively, and the procedural mortality rate was 2%. The overall rate of major complications was 12% for the PM group, 11% for the BVP group, and 2% for the PDA occlusion group. Both PM implantation and BVP have higher rates of major complications overall compared with PDA occlusion (p=0.0151). CONCLUSIONS: The results of this study indicate that the prevalence of major complications and mortality associated with interventional cardiac procedures is low; however, significant differences exist in complication rates between procedures.

Interreader agreement of radiographic left atrial enlargement in dogs and comparison to echocardiographic left atrial assessment.

INTRODUCTION: Assessing left atrial (LA) size is an integral part of the cardiac evaluation in dogs. Left atrial size is routinely evaluated by thoracic radiographs or echocardiography. OBJECTIVES: The objectives of the study were to assess agreement of subjective radiographic left atrial enlargement (LAE) between readers, to compare subjective radiographic LAE with echocardiography, and to assess the accuracy and reliability of commonly used Roentgen signs for LAE. ANIMALS: One hundred one dogs with thoracic radiographs and echocardiography performed on the same day at a veterinary teaching hospital were retrospectively reviewed. METHODS: Thoracic radiographs were reviewed by two cardiologists, two radiologists, and two small animal rotating interns. Radiographs were evaluated for the subjective presence and severity of LAE and for seven Roentgen signs. Echocardiographic LA size was evaluated objectively by the left atrial-to-aortic root ratio and LA volume indexed to body weight. Interreader agreement of radiographic LAE evaluation and agreement between radiographic LAE assessment and echocardiographic LAE were assessed by linearly weighted kappa and intraclass correlation coefficient. RESULTS: Interreader agreement for the presence and degree of radiographic LAE ranged from moderate to substantial. The agreement between subjective radiographic LAE and echocardiographic LAE was moderate. Single Roentgen signs had poor to fair correlation with echocardiographic LAE. CONCLUSIONS: The present study found that interreader agreement for radiographic classification of LAE was substantial among specialists and moderate for all readers. Subjective, global assessment of radiographic LAE is better than using any single Roentgen sign.

Complete transposition of the great arteries with double outlet right ventricle in a dog.

A 2-year old intact male Collie dog presented to the cardiology service at Oregon State University for evaluation of cyanosis and suspected congenital cardiac disease. Echocardiography revealed a constellation of cardiac abnormalities including a single large vessel exiting the right ventricle with a diminutive left ventricular outflow tract, a ventricular septal defect, and marked concentric right ventricular hypertrophy with moderate right atrial dilation. Cardiac-gated computed tomography confirmed the previous anomalies in addition to supporting a diagnosis of complete transposition of the great arteries, double outlet right ventricle, and pulmonic hypoplasia with a single coronary ostium. Prominent bronchoesophageal collateral vessels were concurrently identified. Clinically, the dog was stable despite mild cyanosis that worsened with exercise; no intervention was elected at the time. This case report describes a rare combination of congenital cardiac defects and the usefulness of cardiac-gated cross-sectional imaging in the anatomic diagnosis.

Cardiac-gated computed tomography angiography in three alpacas with complex congenital heart disease.

BACKGROUND: The prevalence of congenital heart disease is higher in camelids than in other domestic species and complex defects, often involving the great vessels, are more frequently encountered in llamas and alpacas than in other species. Some of these complex defects can be difficult to accurately characterize via echocardiography, the most commonly used diagnostic imaging technique to evaluate the heart in veterinary patients. Contrast-enhanced, electrocardiogram (ECG)-gated computed tomography (CT) has proven utility for the evaluation of human patients with certain congenital heart defects, including those with conotruncal septation defects and other abnormalities involving the formation of the great vessels. METHODS: Three alpaca crias, 4 days, 5 weeks and 14 months of age were clinically evaluated and subjected to a complete color-flow Doppler echocardiogram and a contrast-enhanced ECG-gated CT. RESULTS: These alpacas exhibited a variety of clinical findings including lethargy, failure to thrive, exercise intolerance, heart murmur, and/or respiratory difficulty. All three crias were subsequently diagnosed with complex cardiac defects including pulmonary atresia with a ventricular septal defect (VSD), a truncus arteriosus with a large VSD, and a double outlet right ventricle with a large VSD and aortic hypoplasia. In each case, the diagnosis was confirmed by postmortem examination. CONCLUSION: Color flow echocardiographic evaluation identified all of the intra-cardiac lesions and associated flow anomalies but contrast-enhanced ECG-gated CT permitted more accurate assessment of the morphology of the extracardiac structures and permitted a more precise determination of the exact nature and anatomy of the great vessels.

Use of multidetector computed tomography in the assessment of dogs with pericardial effusion.

BACKGROUND: Contrast-enhanced multidetector computed tomography (MDCT) allows high spatial and temporal resolution imaging of cardiac, thoracic, and abdominal structures. Accurate determination of the cause of pericardial effusion (PE) is essential to providing appropriate treatment and prognosis. Echocardiography and pericardial fluid analysis may not differentiate between causes of PE and cannot identify extracardiac metastasis. HYPOTHESIS/OBJECTIVES: Describe the thoracic and abdominal MDCT findings and evaluate the utility of MDCT to differentiate between neoplastic and nonneoplastic causes of PE in dogs. ANIMALS: Eleven client-owned dogs with PE diagnosed by echocardiography. METHODS: Prospective observational study. Transthoracic echocardiography (TTE), 3-view thoracic radiography, and contrast-enhanced thoracic and abdominal MDCT images were evaluated for the presence of cardiac masses, pulmonary metastases, and abdominal masses. Histopathology in 5 dogs and survival analysis in all dogs were evaluated. RESULTS: A neoplastic cause was identified in 6/11 dogs and a nonneoplastic cause was identified in 5/11. Cardiac MDCT findings were consistent with TTE findings in all dogs with right atrial (5/5) and heart base masses (1/1). Pulmonary metastases were identified in 1/11 dogs by thoracic radiography and in 2/11 dogs by MDCT. MDCT identified splenic or hepatic lesions consistent with neoplasia in 6/11 and 5/11 dogs, respectively. Focal MDCT pericardial changes at the pericardiocentesis site were noted in 3/11 dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: Multidetector computed tomography did not improve the detection of cardiac masses in dogs with PE over echocardiography. The benefit of MDCT was primarily in the detection of pulmonary metastases and extracardiac lesions using a single imaging modality.