Ashley B. Saunders

Angiographic classification of patent ductus arteriosus morphology in the dog

OBJECTIVES To characterize angiographic morphology and minimum internal transverse diameter of left-to-right shunting patent ductus arteriosus (PDA) in a large series of dogs. BACKGROUND PDA is the most common congenital cardiac malformation in the dog. Transarterial ductal occlusion is increasingly performed to close this defect. While accurate assessment of ductal morphology and luminal diameter is important to assure optimal occlusion using catheter-delivered devices, such information is currently limited. ANIMALS, MATERIALS AND METHODS In 246 dogs representing 31 breeds with left-to-right shunting PDA, right lateral selective aortic angiograms were recorded and reviewed. RESULTS PDA morphology conformed to four general phenotypes (types I, IIA, IIB, and III) which varied according to degree of ductal tapering, and the presence, absence, or location of abrupt ductal narrowing. Minimum internal ductal diameter for all dogs averaged 2.9mm (median, 2.5mm; range, 1.0-9.5mm) and was not correlated to age or body weight. There was no significant difference in minimum internal diameters between types I, IIA or IIB PDA, whereas, type III PDA was significantly wider (p=0.024) than other phenotypes. The most frequently-encountered variant (type IIA) was identified in 54.4% of cases (average minimum internal diameter, 2.3mm [median, 2.2mm; range, 1.0-5.5mm]). CONCLUSIONS PDA angiographic morphology was categorized based upon the degree, presence, or absence of ductal narrowing, and the location of ductal attenuation. When planning PDA repair, this information should assist planning, selection and deployment of transcatheter occluding devices.

Transarterial ductal occlusion using the Amplatz Canine Duct Occluder in 40 dogs.

OBJECTIVES Describe the result of patent ductus arteriosus (PDA) occlusion using the Amplatz Canine Duct Occluder (ACDO) in 40 dogs. ANIMALS, MATERIAL AND METHODS: Records of the first 41 dogs at Texas A&M University in which ductal occlusion with an ACDO was attempted were reviewed. RESULTS Appropriate device release was achieved in 40 of 41 dogs. Post-release angiography in 39 dogs documented complete occlusion in 27 dogs, trivial residual flow in 7, mild residual flow in 1 and moderate residual flow in 4; angiography was not recorded in one dog. The following day transthoracic color Doppler echocardiography documented complete occlusion in all 40 dogs. One dog required a larger device than could be deployed through the largest sheath accommodated by the femoral artery and the PDA was subsequently closed by surgical ligation. CONCLUSIONS Ductal occlusion using an ACDO has a high rate of initial and 24-h complete occlusion. Ductal occlusion using an ACDO is a safe and efficacious therapy for PDA in dogs. This report confirms the positive clinical outcome of the original report in a large cohort of dogs.

Effect of Pimobendan in Dogs with Preclinical Myxomatous Mitral Valve Disease and Cardiomegaly: The EPIC Study—A Randomized Clinical Trial

Background Pimobendan is effective in treatment of dogs with congestive heart failure (CHF) secondary to myxomatous mitral valve disease (MMVD). Its effect on dogs before the onset of CHF is unknown. Hypothesis/Objectives Administration of pimobendan (0.4–0.6 mg/kg/d in divided doses) to dogs with increased heart size secondary to preclinical MMVD, not receiving other cardiovascular medications, will delay the onset of signs of CHF, cardiac‐related death, or euthanasia. Animals 360 client‐owned dogs with MMVD with left atrial‐to‐aortic ratio ≥1.6, normalized left ventricular internal diameter in diastole ≥1.7, and vertebral heart sum >10.5. Methods Prospective, randomized, placebo‐controlled, blinded, multicenter clinical trial. Primary outcome variable was time to a composite of the onset of CHF, cardiac‐related death, or euthanasia. Results Median time to primary endpoint was 1228 days (95% CI: 856–NA) in the pimobendan group and 766 days (95% CI: 667–875) in the placebo group (P = .0038). Hazard ratio for the pimobendan group was 0.64 (95% CI: 0.47–0.87) compared with the placebo group. The benefit persisted after adjustment for other variables. Adverse events were not different between treatment groups. Dogs in the pimobendan group lived longer (median survival time was 1059 days (95% CI: 952–NA) in the pimobendan group and 902 days (95% CI: 747–1061) in the placebo group) (P = .012). Conclusions and Clinical Importance Administration of pimobendan to dogs with MMVD and echocardiographic and radiographic evidence of cardiomegaly results in prolongation of preclinical period and is safe and well tolerated. Prolongation of preclinical period by approximately 15 months represents substantial clinical benefit.

Pimobendan in Heart Failure Therapy – A Silver Bullet?

Pimobendan is a novel agent with properties that are highly desirable in the clinical management of congestive heart failure (CHF) secondary to both dilated cardiomyopathy (DCM) and chronic degenerative valvular disease in dogs. Review of available data suggests that pimobendan is safe, well tolerated, and leads to enhanced quality of life in dogs with CHF secondary to DCM or chronic valvular disease when used in combination with furosemide or other conventional therapies (e.g., angiotensin-converting enzyme inhibitors, digoxin). Pimobendan leads to a reduction in mortality from CHF associated with DCM, and ongoing studies are evaluating its effects on mortality associated with chronic valvular disease.

Utility of Transesophageal Echocardiography for Transcatheter Occlusion of Patent Ductus Arteriosus in Dogs: Influence on the Decision-Making Process

BACKGROUND Appropriate device selection for transcatheter occlusion of patent ductus arteriosus (PDA) is essential to procedural success. OBJECTIVES To determine if transesophageal echocardiography (TEE) influences device selection for PDA occlusion and to report benefits, limitations, and complications associated with TEE. ANIMALS Twenty-two client-owned dogs with left-to-right shunting PDA. METHODS PDA dimensions were obtained via transthoracic echocardiography (TTE) and then TEE followed by angiography. Based solely on information from TTE and angiography, an initial device type and size were selected. After initial device selection, TEE measurements were disclosed and changes in device selection were recorded. After device release, angiography, TEE, or both were performed to assess occlusion. RESULTS An Amplatz canine duct occluder (ACDO) was securely positioned and released in 21 dogs and an embolization coil was deployed in 1 dog. Based on TEE evaluation, initial selected device type was unchanged but ACDO size was changed in 3 dogs. TEE was utilized throughout the procedure allowing real time visualization of device deployment, release and assessment of closure in 17 dogs. No complications occurred related to TEE. Complete PDA closure was achieved in all dogs. CONCLUSIONS AND CLINICAL IMPORTANCE TEE provided anatomic information regarding PDA morphology that closely approximated angiographic ductal dimensions while aiding in device deployment, release and confirmation of closure. We conclude that TEE provides complementary anatomical and intraprocedural information and is well tolerated in dogs.

Transarterial Ductal Occlusion with the Amplatzer Vascular Plug in 31 Dogs

BACKGROUND Transarterial ductal occlusion with the Amplatzer vascular plug was first reported in dogs by Hogan et al in 2005. HYPOTHESIS Use of the Amplatzer vascular plug is a safe, efficacious method of patent ductus arteriosus (PDA) occlusion. ANIMALS Thirty-one client-owned dogs with PDA. METHODS Records of 31 dogs in which transarterial occlusion of PDA with an Amplatzer vascular plug was attempted were reviewed. RESULTS All dogs had a type II PDA, with 27 dogs having type IIA morphology and 4 dogs having type IIB morphology. Appropriate device deployment was achieved in 29 of 31 dogs. Postdeployment angiography in 21 dogs documented complete occlusion in 10 dogs, trivial residual flow in 5 dogs, mild residual flow in 2 dogs, moderate residual flow in 3 dogs, and severe residual flow in 1 dog. Transthoracic color Doppler echocardiography documented complete occlusion in 22 dogs, whereas 2 dogs had trivial residual flow, 2 dogs had mild residual flow, 2 dogs had mild to moderate residual flow, and 1 dog had severe residual flow. Of the 7 dogs with residual flow, 2 had complete occlusion 2-4 months postoperatively, 1 had moderate residual flow 1 month postoperatively, and 4 were lost to follow-up. One dog required a larger device than was able to be deployed through the largest sheath placed in the femoral artery. Pulmonary embolization of the device occurred in 1 dog. CONCLUSION We conclude that ductal occlusion with an Amplatzer vascular plug is a safe and efficacious therapy for PDA in dogs.

Cardiac troponin I and C-reactive protein concentrations in dogs with severe pulmonic stenosis before and after balloon valvuloplasty.

OBJECTIVE To report cardiac troponin I (cTnI) and C-reactive protein (CRP) concentrations in dogs with severe pulmonic stenosis (PS) before and after balloon valvuloplasty (BV). BACKGROUND Increased morbidity and mortality have been reported with severe PS and histopathologic evidence of myocardial damage is demonstrated with BV. Severity of myocardial injury and inflammation associated with severe PS and BV, as assessed by cTnI and CRP, is unknown. ANIMALS, MATERIALS AND METHODS Serum cTnI and CRP concentrations were measured in dogs with severe PS (n=23) and following BV (n=16). RESULTS Baseline cTnI and CRP were elevated in 7/23 (30.4%) and 8/23 (34.8%) dogs. Median cTnI at baseline and post-BV were 0.20 ng/mL(range, 0.20-1.29 ng/mL) and 2.85 ng/mL (range, 0.21-55.40 ng/mL), respectively. Median CRP at baseline and post-BV were 3.40 microg/mL (range, 0-14.70 microg/mL) and 11.70 microg/mL (range, 4.20-120 microg/mL), respectively. Post-BV concentrations were significantly increased compared to baseline for cTnI (p<0.001) and CRP (p=0.001). CONCLUSIONS Serum cTnI and CRP are increased in dogs with severe PS and following BV. Future studies should evaluate whether biomarkers correlate with severity and prognosis of PS or can be used to guide therapy.

Effect of oral administration of pimobendan in cats with heart failure

OBJECTIVE To determine the effect of PO administration of pimobendan on clinical and echocardiographic variables and survival time in cats with heart failure characterized by ventricular systolic dysfunction. DESIGN Retrospective cohort study. ANIMALS 27 client-owned cats (16 male and 11 female) with heart failure, treated with pimobendan (mean ± SD dosage, 0.26 ± 0.08 mg/kg [0.118 ± 0.036 mg/lb], PO, q 12 h). PROCEDURES Information on medical history, laboratory results, diagnostic imaging findings, treatments received, and survival time were obtained from medical records of cats that received pimobendan because of cardiac disease. When possible, additional follow-up information was obtained through telephone interviews with referring veterinarians and owners. RESULTS The mean ± SD age of all 27 cats was 8.9 ± 5.2 years. All cats had received several cardiac medications. Types of heart disease represented included unclassified cardiomyopathy (CM; n = 11 [41%]), dilated CM (8 [30%]), arrhythmogenic right ventricular CM (4 [15%]), congenital heart disease (3 [11 %]), and hypertrophic CM with regional hypokinesis (1 [4%]). All cats had ventricular systolic dysfunction. One cat with systolic anterior motion of the mitral valve became severely hypotensive after initial administration of pimobendan and was excluded from the survival analysis. Median survival time was 167 days (95% confidence interval, 32 to 339 days). CONCLUSIONS AND CLINICAL RELEVANCE Pimobendan appeared to be well tolerated in cats with heart failure characterized by ventricular systolic dysfunction of various etiologies. Cats with systolic anterior motion of the mitral valve may develop systemic hypotension when treated with pimobendan. Additional studies are needed to establish dosages for pimobendan and its effects before it can be recommended for treatment of cats with CHF.

Long‐Term Outcome in Dogs with Patent Ductus Arteriosus: 520 Cases (1994–2009)

Background Published information regarding survival and long‐term cardiac remodeling after patent ductus arteriosus (PDA) closure in dogs is limited. Objectives To report outcome and identify prognostic variables in dogs with PDA, and to identify risk factors for persistent remodeling in dogs with a minimum of 12 months of follow‐up after closure. Animals Five hundred and twenty client‐owned dogs. Methods Retrospective review of medical records of 520 dogs with PDA. Outcome was determined by contacting owners and veterinarians. Dogs with PDA closure and ≥ 12 months of follow‐up were asked to return for a re‐evaluation. Results In multivariable analysis of 506 dogs not euthanized at the time of diagnosis, not having a PDA closure procedure negatively affected survival (HzR = 16.9, P < .001). In 444 dogs undergoing successful PDA closure, clinical signs at presentation (HzR = 17, P = .02), concurrent congenital heart disease (HD) (HzR = 4.8, P = .038), and severe mitral regurgitation (MR) documented within 24 hours of closure (HzR = 4.5, P = .028) negatively affected survival. Seventy‐one dogs with ≥ 12 months follow‐up demonstrated a significant reduction in radiographic and echocardiographic measures of heart size (P = 0) and increased incidence of acquired HD (P = .001) at re‐evaluation. Dogs with increased left ventricular size and low fractional shortening at baseline were more likely to have persistent remodeling at re‐evaluation. Conclusions and Clinical Importance Patent ductus arteriosus closure confers important survival benefits and results in long‐term reverse remodeling in most dogs. Clinical signs at presentation, concurrent congenital HD, and severe MR negatively affect survival. Increased left ventricular systolic dimensions and systolic dysfunction at baseline correlated significantly with persistent remodeling.

Multi-centered investigation of a point-of-care NT-proBNP ELISA assay to detect moderate to severe occult (pre-clinical) feline heart disease in cats referred for cardiac evaluation ☆

OBJECTIVE To prospectively evaluate the diagnostic accuracy of a point-of-care (POC) N-terminal pro-B-type natriuretic peptide (NT-proBNP) ELISA to assess the likelihood of moderate to severe occult heart disease (OcHD) in a clinical population of cats suspected to have heart disease. ANIMALS One hundred and forty-six asymptomatic client-owned cats with a heart murmur, gallop rhythm, arrhythmia, or cardiomegaly. METHODS Physical examination, blood pressure measurement and echocardiography were performed prospectively. Point-of-care ELISA was visually assessed as either positive or negative by a reader blinded to the echocardiographic results. RESULTS Forty-three healthy cats, 50 mild OcHD, 31 moderate OcHD, 6 severe OcHD, and 16 cats equivocal for OcHD were examined. Cats with OcHD included 65 with hypertrophic cardiomyopathy, 6 with restrictive or unclassified cardiomyopathy, 1 with arrhythmogenic right ventricular cardiomyopathy, and 15 with non-cardiomyopathic forms of heart disease. Point-of-care ELISA differentiated cats with moderate or severe OcHD with sensitivity/specificity of 83.8%/82.6% and overall accuracy of 82.9%. Positive POC ELISA increased likelihood of moderate or severe OcHD by a factor of 4.8 vs. those that tested negative. Point-of-care ELISA differentiated cats with moderate or severe cardiomyopathic OcHD with sensitivity/specificity of 88.6%/81.3% and overall accuracy of 83.2%. CONCLUSION In a select sample of cats referred for cardiac evaluation, positive POC NT-proBNP ELISA increases likelihood of moderate to severe OcHD while negative POC NT-proBNP ELISA result excludes moderate to severe OcHD.