Transesophageal echocardiography using a microprobe for determination of transcatheter procedural candidacy, device selection, and procedural monitoring in small dogs with patent ductus arteriosus.

INTRODUCTION: Small dogs with patent ductus arteriosus (PDA) may be unable to undergo transesophageal echocardiography (TEE) with traditional probes. OBJECTIVES: To report the utility of TEE using a microprobe in dogs weighing less than 4 kg diagnosed with PDA for determination of transcatheter procedural candidacy, device selection, and intraoperative procedural guidance. ANIMALS: Eight dogs weighing less than 4 kg diagnosed with PDA. MATERIALS AND METHODS: All dogs had standard transthoracic echocardiography and microprobe TEE imaging. The quality of TEE images was graded as optimal, adequate, or poor. The ability of TEE to assess PDA anatomy, determine procedural candidacy, provide procedural guidance, detect deployed devices, and assess residual flow was recorded. RESULTS: The median age of included dogs was 6.4 months (range: 3.2-15.7 months) and the median body weight was 2.2 kg (range: 1.4-3.8 kg). Microprobe TEE images were adequate or optimal in all dogs and were integral for guiding procedural candidacy decisions. Transcatheter procedures were not pursued in two dogs based on TEE images. In the other six dogs, TEE procedural guidance was useful during transvenous (n = 5) and transarterial (n = 1) PDA occlusion attempts. Each deployed device (n = 4) was easily detected with the TEE microprobe. Real-time confirmation of adequate device sizing and placement was possible prior to release and residual flow could be monitored after release. CONCLUSIONS: Transesophageal echocardiography using a microprobe in dogs weighing less than 4 kg diagnosed with PDA allowed for characterization of PDA anatomy and determination of transcatheter procedural candidacy. Microprobe TEE images were integral for PDA device selection and offered valuable intraoperative procedural guidance.

Abundant triatomines in Texas dog kennel environments: Triatomine collections, infection with Trypanosoma cruzi, and blood feeding hosts.

Triatomine insects are vectors of the protozoan parasite Trypanosoma cruzi- the causative agent of Chagas disease. Chagas disease is endemic to Latin America and the southern United States and can cause severe cardiac damage in infected mammals, ranging from chronic disease to sudden death. Identifying interactions among triatomines, T. cruzi discrete typing units (DTUs), and blood feeding hosts is necessary to understand parasite transmission dynamics and effectively protect animal and human health. Through manual insect trapping efforts, kennel staff collections, and with the help of a trained scent detection dog, we collected triatomines from 10 multi-dog kennels across central and south Texas over a one-year period (2018-2019) and tested a subset to determine their T. cruzi infection status and identify the primary bloodmeal hosts. We collected 550 triatomines, including Triatoma gerstaeckeri (n = 515), Triatoma lecticularia (n = 15), Triatoma sanguisuga (n = 6), and Triatoma indictiva (n = 2), with an additional 10 nymphs and 2 adults unable to be identified to species. The trained dog collected 42 triatomines, including nymphs, from areas not previously considered vector habitat by the kennel owners. Using qPCR, we found a T. cruzi infection prevalence of 47 % (74/157), with T. lecticularia individuals more likely to be infected with T. cruzi than other species. Infected insects harbored two T. cruzi discrete typing units: TcI (64 %), TcIV (23 %), and mixed TcI/TcIV infections (13 %). Bloodmeal host identification was successful in 50/149 triatomines, revealing the majority (74 %) fed on a dog (Canis lupus), with other host species including humans (Homo sapiens), raccoons (Procyon lotor), chickens (Gallus gallus), wild pig (Sus scrofa), black vulture (Coragyps atratus), cat (Felis catus), and curve-billed thrasher (Toxostoma curviostre). Given the frequency of interactions between dogs and infected triatomines in these kennel environments, dogs may be an apt target for future vector control and T. cruzi intervention efforts.

Current use of transesophageal echocardiography in animals.

The unique imaging capabilities of transesophageal echocardiography (TEE) make it a valuable tool for characterizing the structure and function of the heart and for providing procedural monitoring. With the creation of new devices and expansion of procedural options with increased applications, multiplanar and three-dimensional imaging with TEE can be essential for clinical decision making. A description of the indications and clinical application of TEE in animals while highlighting probe characteristics, limitations and patient safety are the focus of this review. The increased availability of three-dimensional imaging in smaller probes, advanced applications including photorealistic and fusion imaging, and the development of recommended standards for performing a comprehensive TEE imaging study including training guidelines may facilitate the use of TEE in the veterinary field.

Use of physical examination, electrocardiography, radiography, and biomarkers to predict echocardiographic stage B2 myxomatous mitral valve disease in preclinical Cavalier King Charles Spaniels.

INTRODUCTION: Cavalier King Charles Spaniels (CKCS) are predisposed to developing myxomatous mitral valve disease (MMVD). Dogs with stage B2 MMVD benefit from medication. OBJECTIVES: To develop (1) breed-specific cut-offs for individual screening tests and (2) predictive models utilizing physical examination (PE), ECG, radiograph, and blood-based biomarker variables in combination for identification of echocardiographic stage B2 MMVD in preclinical CKCS. ANIMALS: Adult, preclinical CKCS not receiving cardiac medications (N = 226). MATERIALS AND METHODS: Prospective, cross-sectional study. Enrolled CKCS underwent PE, ECG, radiography, Doppler blood pressure measurement, echocardiography, and biomarker testing. Dogs were grouped by MMVD stage using echocardiography only. The discriminatory ability of individual tests to identify stage B2 was assessed, and prediction models were developed using variables derived from four 'tests' (PE, ECG, radiography, and biomarkers). RESULTS: N-terminal pro-B-type natriuretic peptide (NT-proBNP) and radiographic vertebral heart size (VHS) had the best discriminatory ability of individual diagnostic tests to differentiate stage A/B1 CKCS from stage B2, with an area under the curve (AUC) of 0.855 and 0.843, respectively. An NT-proBNP ≥1138 pmol/L or a VHS ≥11.5 had high specificity for predicting stage B2 (90.1% and 90.6%, respectively). Prediction models incorporating variables from multiple tests had better discriminatory ability than single tests. The four-test prediction model had an AUC of 0.971. Three and two-test models had AUCs ranging between 0.925-0.959 and 0.895-0.949, respectively. CONCLUSIONS: Both NT-proBNP and VHS have good utility for predicting echocardiographic stage B2 MMVD in CKCS as individual tests. Prediction models incorporating multiple test variables have superior discriminatory ability.

Advanced imaging in an adult dog with anomalous origin of the left coronary artery from the pulmonary artery and extensive collateral coronary circulation.

A three-year-old, spayed female, Bichon Frise was diagnosed with an anomalous origin of the left coronary artery from the pulmonary artery, a rare congenital coronary artery defect which has only been reported in two other dogs. Echocardiography was initially performed, though the final diagnosis was made with angiography and computed tomography angiography. An extensive network of collateral coronary circulation allowed for communication between the dilated, tortuous right coronary artery, and the anomalous left coronary artery. Though collateral circulation likely prolonged the patient's life, it is suspected that coronary steal phenomenon and chronic myocardial ischemia ultimately led to fatal ventricular arrhythmias. The dog died suddenly at the age of six, three years after initial diagnosis.

Evaluation of two probes for transesophageal echocardiography in small dogs: imaging capabilities, image quality, and usability.

INTRODUCTIONS: Patient size is a limiting factor for transesophageal echocardiography (TEE) in small dogs. The objective of this study was to describe imaging capabilities of two probes for TEE in small dogs. ANIMALS, MATERIALS, AND METHODS: Prospective study in 10 client-owned dogs weighing <4 kg with congenital heart disease (CHD). Dogs had TEE performed with a microprobe (10T-D, GE Medical) and intracardiac echocardiography (ICE) catheter-based probe (AcuNav™, Biosense Webster) in the esophagus in alternating order. Ease of placement, ability to acquire images of the CHD, image quality, and probe limitations were recorded. RESULTS: Median weight was 2.4 kg (range, 1.0-3.2). Congenital abnormalities included patent ductus arteriosus (n = 9) and pulmonary valve stenosis (n = 1). The 10T-D microprobe was easy to place (n = 8) or achievable with gentle manipulation (n = 2), and image quality of the CHD was optimal (n = 8), adequate (n = 1), or poor (n = 1). The ICE probe was difficult to place in the esophagus even with an external support system (n = 9) or could not be placed (n = 1), and image quality of the CHD was optimal (n = 2), adequate (n = 3), or poor (n = 5). Both probes provided images in a 1.0-kg dog. Probe limitations included lack of lateral motion (microprobe), the need for an external support system (ICE probe) and inability to consistently maintain contact with the esophagus (ICE probe). CONCLUSION: The 10T-D microprobe provided high-quality TEE images more consistently than the ICE probe in the majority of dogs in this study; however, the lack of lateral motion can diminish its utility in some dogs.

Echocardiographic measurement of the mitral valve in normal Cavalier King Charles spaniels: repeatability, optimal future study methods, and preliminary reference intervals.

INTRODUCTION/OBJECTIVES: Cavalier King Charles spaniels (CKCS) are ideal candidates for longitudinal study of myxomatous mitral valve (MV) disease and stage B1 clinical trials; however, the optimization of MV measurement acquisition and repeatability must be better defined to realize this potential. Additionally, breed-specific reference ranges for CKCS MV measurements are lacking. Study objectives were to assess measurement repeatability and define optimal methods for the longitudinal study of echocardiographic MV anatomy and to define preliminary, two-dimensional echocardiographic reference ranges for MV measurements in CKCS. ANIMALS: Forty CKCS between 10 and 24 months old. MATERIALS AND METHODS: Pre- and post-sedation two-dimensional echocardiographic images optimized for the MV were obtained. The length, width, and area of the anterior and posterior leaflets and the diameter of the MV annulus at end-diastole and end-systole were measured. Measurement repeatability was assessed using % coefficient of variation and repeatability coefficients. RESULTS: Intraoperator repeatability was best for the operator with previous MV measurement experience, with comparable results for the experienced operator measuring the second operator's images, mimicking a core echocardiography laboratory setting. Except for MV annulus diameter at end-systole, sedation had no significant effect on any MV measurements, nor did it impact measurement repeatability. Preliminary, breed-specific reference ranges were defined for the population, with CKCS often noted to have a larger annular diameter at end-systole than end-diastole. CONCLUSIONS: Optimal methods for longitudinal study of the MV in CKCS have been proposed, as have two-dimensional preliminary echocardiographic reference ranges for CKCS MV measurements. The MV annulus in CKCS may differ from other breeds.

Hybrid balloon valvuloplasty for management of severe mitral stenosis in four symptomatic, adult dogs.

Four adult dogs weighing <10 kg presented for the evaluation of severe mitral valve stenosis with clinical signs. Owing to the size of the dogs, a hybrid surgical and interventional approach was utilized for balloon valvuloplasty. A left lateral thoracotomy was performed to allow direct entry through the left atrial wall. Transesophageal echocardiography was utilized for the entirety of the procedure in all dogs, and fluoroscopy was additionally used in two dogs. One dog had mild to moderate intra-operative bleeding from the left atrial wall during the procedure, but no other intra-operative complications were observed. No dogs developed a clinically relevant amount of worsened mitral regurgitation. Based on mitral leaflet mobility and transmitral flow profiles, there was perceived improvement in all four dogs. One dog died 6 h after extubation due to respiratory arrest. The remaining dogs survived to discharge and had resolution of clinical signs at home and discontinuation of heart failure medications. One dog died of an unknown cause at five months and another developed atrial fibrillation, and the owners elected to euthanize at ten months after the procedure. One dog continues to do well six months after the procedure as of the time of this writing. Hybrid balloon valvuloplasty can be a viable management option for small breed dogs with severe mitral stenosis exhibiting clinical signs, and both transesophageal echocardiography and fluoroscopy can be used intra-operatively to assist in successful procedural outcomes.

Feasibility and clinical utility of transvenous intracardiac echocardiography in conscious, sedated horses.

INTRODUCTION/OBJECTIVES: Intracardiac echocardiography (ICE) is a method of obtaining echocardiographic images with a steerable ultrasound catheter placed within the heart via a venous or arterial approach. The objectives of this study were to assess the feasibility of a 5-10 MHz, 8 French, 90 cm ICE catheter to evaluate cardiac structures and function in standing, sedated horses, and describe standard views in this species. ANIMALS: Ten apparently healthy horses weighing 458.1-618.2 kg from a university teaching herd. MATERIALS AND METHODS: Each horse had a physical examination, transthoracic echocardiography, and ICE performed through a 10 French introducer percutaneously placed in the right jugular vein in the proximal third of the neck with continuous ECG monitoring using telemetry. RESULTS: Three intracardiac echocardiography positions (cranial right atrium, mid right atrium, and right ventricle) with seven views were described with the associated 2D, pulse wave Doppler, continuous wave Doppler, color Doppler, and M-mode image acquisition standardized by referencing the intracardiac positions and common landmarks. The positions were confirmed with simultaneous transthoracic echocardiography. The procedure was well tolerated with only mild, occasional ventricular, and supraventricular arrhythmias that resolved with intracardiac echocardiography catheter repositioning. CONCLUSIONS: Intracardiac echocardiography is feasible, safe, and allows for the acquisition of diagnostic images in conscious, sedated horses.

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.

Pre-procedural femoral vessel ultrasound in dogs with patent ductus arteriosus: diameter, image quality and relationship with arterial catheterization.

INTRODUCTION: Objectives: Patent ductus arteriosus (PDA) in dogs is often treated via minimally invasive transvascular occlusion using femoral artery access. This study compared ultrasound-derived diameter and image quality of the right femoral artery (RFA) and vein (RFV) in dogs with PDA using a linear ultrasound probe (L-P) and phased-array transthoracic echocardiography probe (TTE-P). The case outcome was assessed. ANIMALS, MATERIALS & METHODS: Forty-five client-owned dogs with PDA were prospectively enrolled. Ultrasound-measured RFA and RFV diameters were obtained on images acquired with both probes pre-operatively and compared using Bland-Altman plots. The image quality of RFA and RFV was scored on L-P and TTE-P images. RESULTS: Comparison of RFA and RFV diameter from L-P versus TTE-P images revealed: [Mean difference (limits of agreement): RFA = 0.009 mm (-0.78-0.79 mm), RFV = 0.523 mm (-1.75-2.79 mm)]. Image quality scores were significantly higher for L-P than TTE-P (P < 0.0001). In six small dogs, measurable images were unattainable with TTE-P. Dogs of similar body weight had variable RFA diameters. Twenty-seven dogs had RFA catheterization. In 21/27 dogs, RFA diameter exceeded the external diameter of the introducer used for catheterization, and in 6/27, it was smaller. CONCLUSIONS: Pre-procedural ultrasound of the RFA in dogs with PDA is useful given variable RFA diameter relative to body weight. Despite poorer image quality, RFA diameters from TTE-P images were very similar to L-P images on average, suggesting TTE-Ps are suitable for pre-procedural planning in most dogs. Vasospasm, hypotension or differences in the location of ultrasound measurement versus catheterization might produce variation in pre-procedural versus intraoperative RFA size.

Prediction of clinically important acquired cardiac disease without an echocardiogram in large breed dogs using a combination of clinical, radiographic and electrocardiographic variables.

INTRODUCTION: Large breed (LB) dogs develop dilated cardiomyopathy (DCM) and myxomatous mitral valve disease (MMVD). Echocardiography is required for a definitive diagnosis but is not always available. Our objective was to assess the clinical utility of thoracic radiographs alone and in combination with physical examination and electrocardiography findings for the prediction of clinically important DCM or MMVD in LB dogs. ANIMALS: Four hundred fifty-five client-owned dogs ≥20 kg with concurrent thoracic radiographs and echocardiogram. MATERIALS AND METHODS: Medical records were reviewed and stored thoracic radiographs and echocardiographic images were measured to classify dogs as normal heart size (NHS), preclinical DCM, clinical DCM, preclinical MMVD (with cardiomegaly), clinical MMVD, or equivocal. Dogs with preclinical MMVD, without cardiomegaly, were classified as NHS. Vertebral heart size (VHS) and vertebral left atrial size (VLAS) were measured. Receiver operating characteristic curves and prediction models were derived. RESULTS: Prevalence of MMVD (39.3%) was higher than the prevalence of DCM (24.8%), though most MMVD dogs (67.0%) lacked cardiomegaly and were classified as NHS for analysis. The area under the curve for VHS to discriminate between NHS and clinical DCM/MMVD or preclinical DCM/MMVD was 0.861 and 0.712, respectively, while for VLAS, it was 0.891 and 0.722, respectively. Predictive models incorporating physical examination and electrocardiography findings in addition to VHS/VLAS increased area under the curve to 0.978 (NHS vs. clinical DCM/MMVD) and 0.829 (NHS vs. preclinical DCM/MMVD). CONCLUSIONS: Thoracic radiographs were useful for predicting clinically important DCM or MMVD in LB dogs, with improved discriminatory ability when physical examination abnormalities and arrhythmias were accounted for.

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.

Histologic comparison in two Doberman pinschers with a dilated cardiomyopathy phenotype.

Idiopathic dilated cardiomyopathy (DCM) is a common acquired cardiac disease in large breed dogs with a high prevalence in Doberman pinschers. It is characterized histologically by attenuated wavy fibers and fatty infiltration with degeneration. The phenotypic appearance of DCM includes ventricular dilation with systolic dysfunction and ventricular arrhythmias. These changes can be caused by other etiologies, including infectious, toxic, metabolic, and nutritional deficiencies. Chagas disease is the result of an infection with the protozoal parasite, Trypanosoma cruzi, transmitted by an insect vector. Histopathology of the myocardium is characterized by inflammation, fibrosis, and pseudocysts containing T. cruzi amastigotes. Differentiating idiopathic DCM from infectious myocarditis can be challenging when the clinical presentation and diagnostic test results are similar in affected dogs. We present thoracic radiographs, echocardiography, and post-mortem histopathology images obtained from two Doberman pinschers with similar signalment, clinical presentation, and electrocardiographic and echocardiographic appearance but with different appearing radiographs and different etiologies for their heart disease, one with idiopathic DCM and one with myocarditis attributed to Chagas disease, to highlight the value of considering alternative etiologies for DCM to guide additional clinical evaluation and owner counseling.

Palliative combined cutting and high-pressure balloon valvuloplasty in six dogs with severe, symptomatic subaortic stenosis.

INTRODUCTION/OBJECTIVES: Severe subaortic stenosis (SAS) is a congenital heart defect in dogs that often results in clinical signs and reduced survival. The objective of this study was to describe characteristics of dogs with severe, symptomatic SAS who underwent combined cutting and high-pressure balloon valvuloplasty (CB/HPBV). ANIMALS, MATERIALS, AND METHODS: Retrospective description of the clinical characteristics, CB/HPBV procedural deviations from reported methodology and outcomes in a series of six client-owned dogs with severe, symptomatic SAS. RESULTS: Breeds included two each of Newfoundland, Golden retriever, and German shepherd. Median age was 10.1 months (range: 5-72.3 months), and median weight was 25.5 kg (range: 21.8-36.4 kg). Before CB/HPBV, clinical signs were present in all dogs; four were managed for congestive heart failure (CHF). Three dogs had concurrent congenital heart disease. Median Doppler-estimated left ventricular outflow tract pressure gradient was pre-operatively 149.7 mmHg (range: 89.9-254.7 mmHg) and post-operatively 134.1 mmHg (range: 83.9-181.2 mmHg). Median aortoseptal angle was steep at 136° (range: 109-143°). Clinical improvement was documented in all dogs, based on temporary discontinuation of diuretics and/or owner-perceived reduction in clinical signs. At the time of writing, three dogs had died suddenly, one was euthanized because of recurrence of clinical signs, and one died in CHF. Median survival time was 26.4 months after procedure (range: 6.3-45.8 months). One dog remained alive at 44 months after procedure. CONCLUSIONS: Palliative CB/HPBV is a potential therapeutic option for dogs with severe, symptomatic SAS complicated by concurrent congenital heart disease, arrhythmias, or CHF.

A pictorial view of the three-dimensional representation and comparative two-dimensional image orientation derived from computed tomography angiography in a dog with a patent ductus arteriosus.

Patent ductus arteriosus (PDA) occlusion is one of the more common cardiovascular procedures performed in dogs. Two-dimensional imaging has been the primary method of visualizing the PDA and is the basis of its morphologic description. Transesophageal echocardiographic imaging has further characterized the three-dimensional (3D) variation in ductal morphology and shape (circle, oval). An accurate assessment of the shape and dimensions of a PDA in an individual dog is important when making decisions about definitive closure. Ductal measurements from angiography and echocardiography have not been found to be interchangeable, likely related in part to the static two-dimensional measurement of a 3D structure. We describe the use of computed tomography angiography (CTA) images imported into three software programs as a tool to provide 3D information about PDA anatomy including a comparison to images obtained from classic two-dimensional imaging modalities. These images provide an example of thorax and heart position related to transducer position and the orientation of image acquisition to demonstrate why measurements do not always compare. Additionally, 3D images are useful as a training tool and in the development of devices and training opportunities. Multidimensional imaging provides a unique representation of the 3D anatomical structure of the ductus arteriosus as displayed in these images from a dog with a PDA.

Quantitative assessment of two- and three-dimensional transthoracic and two-dimensional transesophageal echocardiography, computed tomography, and magnetic resonance imaging in normal canine hearts.

INTRODUCTION: The objective of the study was to evaluate the accuracy of two- and three-dimensional (2D, 3D) transthoracic echocardiography (TTE), 2D transesophageal echocardiography, and computed tomography angiography (CTA) compared with cardiac magnetic resonance imaging (CMR) in normal dogs and to assess repeatability of 2D and 3D TTE for the assessment of left ventricular (LV) and left atrial (LA) dimensions. ANIMALS: The study was performed on six healthy dogs. MATERIALS AND METHODS: Transthoracic echocardiography, transesophageal echocardiography, CTA, and CMR were performed on each dog. Right ventricular (RV) and LV volumes (in systole and diastole), ejection fraction (EF), and LA and right atrial (RA) volumes were assessed. Repeatability and intrarater and interrater measurements of variability were quantified by average coefficient of variation (CV) for 2D and 3D TTE. RESULTS: No clinically relevant differences in LV volume were detected between CMR and all modalities. Importantly, 3D TTE had the lowest CV (6.45%), correlated with (rs = 0.62, p = 0.01), and had the highest overlap in distribution with CMR (OVL >80%). Left ventricular EF and LA size via CTA compared best with CMR and RV and RA volumes were best estimated by 3D TTE. Assessment of LV and LA volumes via 3D TTE had moderate repeatability (15-21%) compared with LV M-mode measurements and 2D LA-to-aortic ratio (<10%), respectively. For LV size, interrater CV for 3D TTE (19.4%) was lower than 2D TTE (23.1%). CONCLUSIONS: Measurements of LV, RV, and RA volumes via 3D TTE and LA volume and LV EF assessed by CTA compared best with CMR. Three-dimensional echocardiography had lower interrater and intrarater CV compared with 2D TTE.

Artificial cardiac pacemaker placement in dogs with a cohort of myocarditis suspects and association of ultrasensitive cardiac troponin I with survival.

INTRODUCTION: Artificial cardiac pacemakers (APs) are a common treatment for symptomatic bradyarrhythmias in dogs, some of which may be triggered by underlying myocarditis. Severely elevated cardiac troponin I (cTnI) concentrations support a diagnosis of myocarditis. The association of ultrasensitive-cTnI (US-cTnI) concentration with survival in a large cohort of dogs receiving APs is not described. ANIMALS, MATERIALS, AND METHODS: The study included 110 dogs receiving APs over a 5-year period. Medical records were retrospectively reviewed to characterize the entire population receiving APs, with further analysis in dogs with preprocedural US-cTnI concentrations (n = 64) classified as normal/group 1 (n = 11), mildly to moderately elevated/group 2 (n = 27), and severely elevated/myocarditis suspects/group 3 (n = 26). RESULTS: Median survival time was 1079 days for the entire population, 1167 days for group 2, 949 days for group 3, and not met in group 1. There was not a statistically significant difference in survival between group 2 and group 3. Overall, US-cTnI had a mild, negative association with survival. Age had a stronger negative association. Infectious etiologies were identified in a minority of group 3 cases. A possible association between severely elevated US-cTnI and a sudden death outcome was noted. CONCLUSIONS: The negative association of US-cTnI with survival outcomes was mild, with age having a larger effect. Although a sudden death outcome may be seen more commonly in myocarditis suspects, group 3 survival time was similar to that of the entire canine population. Plausible infectious causes of myocarditis were infrequently identified.

Longitudinal Analysis of Quality of Life, Clinical, Radiographic, Echocardiographic, and Laboratory Variables in Dogs with Preclinical Myxomatous Mitral Valve Disease Receiving Pimobendan or Placebo: The EPIC Study.

BACKGROUND: Changes in clinical variables associated with the administration of pimobendan to dogs with preclinical myxomatous mitral valve disease (MMVD) and cardiomegaly have not been described. OBJECTIVES: To investigate the effect of pimobendan on clinical variables and the relationship between a change in heart size and the time to congestive heart failure (CHF) or cardiac-related death (CRD) in dogs with MMVD and cardiomegaly. To determine whether pimobendan-treated dogs differ from dogs receiving placebo at onset of CHF. ANIMALS: Three hundred and fifty-four dogs with MMVD and cardiomegaly. MATERIALS AND METHODS: Prospective, blinded study with dogs randomized (ratio 1:1) to pimobendan (0.4-0.6 mg/kg/d) or placebo. Clinical, laboratory, and heart-size variables in both groups were measured and compared at different time points (day 35 and onset of CHF) and over the study duration. Relationships between short-term changes in echocardiographic variables and time to CHF or CRD were explored. RESULTS: At day 35, heart size had reduced in the pimobendan group: median change in (Δ) LVIDDN -0.06 (IQR: -0.15 to +0.02), P < 0.0001, and LA:Ao -0.08 (IQR: -0.23 to +0.03), P < 0.0001. Reduction in heart size was associated with increased time to CHF or CRD. Hazard ratio for a 0.1 increase in ΔLVIDDN was 1.26, P = 0.0003. Hazard ratio for a 0.1 increase in ΔLA:Ao was 1.14, P = 0.0002. At onset of CHF, groups were similar. CONCLUSIONS AND CLINICAL IMPORTANCE: Pimobendan treatment reduces heart size. Reduced heart size is associated with improved outcome. At the onset of CHF, dogs treated with pimobendan were indistinguishable from those receiving placebo.

Transcatheter closure of a small atrial septal defect with an Amplatzer™ patent foramen ovale occluder in a working dog with cyanosis and exercise intolerance at high altitude.

A 6.5-year-old male Border Collie presented for transcatheter closure of an atrial septal defect due to exercise intolerance and cyanosis while working and training at altitude. A small, left-to-right shunting secundum atrial septal defect was confirmed with no evidence of significant right-sided volume overload. Pulmonary hypertension with subsequent right-to-left interatrial shunting occurring during exercise at high altitude was suspected and prompted the closure of the defect due to the dog's continued athletic requirements. The anatomy of the defect prompted use of a patent foramen ovale occluder rather than an atrial septal defect occluder, which was deployed using a combination of fluoroscopic and transesophageal echocardiographic guidance. The owner did not report continued exercise intolerance or cyanosis and the dog's lifestyle and residence at altitude was unchanged.