Comparison of echocardiographic measurements and cardiac biomarkers in healthy dogs eating nontraditional or traditional diets.

BACKGROUND: There has been a recent association between nontraditional diets and development of diet-associated dilated cardiomyopathy (DCM) in dogs. HYPOTHESIS/OBJECTIVES: To compare echocardiographic measurements and cardiac biomarkers between healthy dogs eating nontraditional vs traditional diets. We hypothesized that dogs eating nontraditional diets would have lower measures of systolic myocardial performance compared to dogs eating traditional diets. ANIMALS: Forty-six healthy dogs: 23 eating nontraditional diets and 23 eating traditional diets. METHODS: Prospective, cross-sectional study. Dogs were divided into groups based on diet ingredients. Dogs underwent 2-dimensional (2D), 3-dimensional (3D), and Doppler echocardiographic examinations and analysis of plasma N-terminal prohormone of B-type natriuretic peptide, serum cardiac troponin I, and whole blood and plasma taurine concentrations. RESULTS: Mean 2D ejection fraction (EF) was lower for dogs eating nontraditional diets (48.65 ± 7.42%) vs dogs eating traditional diets (56.65 ± 4.63%; P < .001; mean difference 8.0% [4.0%-12.0%] 95% confidence interval [CI]). Mean 3D EF was lower for dogs eating nontraditional diets (45.38 ± 7.35%) vs dogs eating traditional diets (57.58 ± 4.84%; P < .001; 12.0% [8.0%-16.0%] 95% CI). Mean 2D left ventricular end-systolic volumes, indexed to body weight, were significantly higher in dogs eating nontraditional diets (1.46 ± 0.08 mL/kg) vs dogs eating traditional diets (1.06 ± 0.08 mL/kg; P = .002; 0.4 mL/kg [0.18-0.62 mL/kg] 95% CI). CONCLUSIONS AND CLINICAL IMPORTANCE: Healthy dogs eating nontraditional diets had lower indices of systolic function and larger left ventricular volumes compared to dogs eating traditional diets. Screening of apparently healthy dogs eating nontraditional diets might allow for early detection of diet-associated DCM.

Retrospective evaluation of hypertrophic cardiomyopathy in 68 dogs.

BACKGROUND: There is a lack of clinical data on hypertrophic cardiomyopathy (HCM) in dogs. HYPOTHESIS/OBJECTIVES: To investigate signalment, clinical signs, diagnostic findings, and survival in dogs with HCM. ANIMALS: Sixty-eight client-owned dogs. METHODS: Retrospective multicenter study. Medical records were searched between 2003 and 2015. The diagnosis of left ventricular (LV) hypertrophy was made by echocardiographic examination. RESULTS: Three hundred and forty-five dogs with LV hypertrophy were identified, of which 277 were excluded. The remaining 68 dogs were 0.3 to 14 years old and predominantly <10 kg (85%), and without a sex predilection. Twenty-four % were Shih Tzu and 24% terrier breeds. Most (80%) had a systolic heart murmur. Owner-determined exercise intolerance (37%) and syncope (18%) were most commonly reported signs. The majority (84%) of dogs had symmetrical LV hypertrophy, whereas asymmetrical septal and LV free wall hypertrophy was observed in 9% and 6% of dogs, respectively. Isolated basal interventricular septal hypertrophy was not observed. Commonly recorded were systolic anterior motion of the mitral valve (60%) and LV diastolic dysfunction (89% of dogs where diastolic function was evaluated). Six dogs died unexpectedly, and 3 developed congestive heart failure. Known survival times were between 1 day and 114 months after diagnosis. CONCLUSIONS AND CLINICAL IMPORTANCE: Hypertrophic cardiomyopathy in dogs should be considered as a differential diagnosis if LV hypertrophy is identified. Small breed dogs are overrepresented, and it is uncommon for dogs with HCM to develop CHF although sudden death can occur.

Hemodynamic, Echocardiographic, and Sedative Effects of Oral Gabapentin in Healthy Cats.

The study objective was to evaluate sedative, hemodynamic, and echocardiographic effects of cats receiving single-dose, oral gabapentin. A prospective, double-blinded, placebo-controlled, crossover study was conducted with 10 client-owned cats. Vital parameters, physical exam, blood pressure, echocardiography, and sedation scoring were performed at each visit within 2 hr of receiving either a placebo or gabapentin capsule. Vital parameters, blood pressure recordings, and echocardiographic measurements were compared between baseline, gabapentin, and placebo; interobserver agreement for sedation scoring and correlation between variables were also evaluated. Seven of 10 cats exhibited mild sedation within 120 min after receiving gabapentin, and no adverse events occurred. Significant differences were detected with two-dimensional fractional shortening (P = .022), left ventricular internal diameter in systole using M-mode (P = .014), and left atrial volume (P < .0001). Interobserver agreement for sedation scoring was near-perfect (κ = 0.84). No significant correlation was found for gabapentin dosage and sedation score. Single-dose oral gabapentin is well tolerated in healthy cats and produces a modest decrease in several echocardiographic parameters of systolic function; however, all affected variables remained within established reference ranges. These results suggest gabapentin may be an appropriate sedative to administer before echocardiography in cats necessitating mild sedation.

Investigation of the short-term effects of a transdermal formulation of atenolol in healthy cats.

OBJECTIVE: To investigate associations between short-term treatment with a previously described compounded transdermal formulation of atenolol and heart rate in cats. ANIMALS: 11 healthy adult cats. PROCEDURES: Cats received the atenolol gel formulation (gradually increased from 12.5 mg/cat, q 24 h to 25 mg/cat, q 12 h) by application to the pinnae at home over a 10-day period in a prospective, experimental study. On day 10, cats were hospitalized for measurement of serum atenolol concentrations 3, 6, and 12 hours after the morning treatment. Mean heart rate measured at the 3- and 6-hour time points was compared with a baseline value (measured at enrollment). RESULTS: All cats completed the study; 4 were excluded from analyses after an apparent formulation error was detected in 1 batch. Two cats had minor adverse effects (localized erythema of the pinna). Five of 7 cats had serum atenolol concentrations ≥ 260 ng/mL (considered therapeutic) at ≥ 1 time point. Heart rate had a strong negative correlation (r = -0.87) with serum atenolol concentration. A 90-day drug stability investigation of 4 formulations (identical to the intended study treatment except for pH [range, 6.5 to 7.7]) revealed an apparent decrease in atenolol concentration at a pH of 7.7. CONCLUSIONS AND CLINICAL RELEVANCE: Topical administration of the formulation as described resulted in targeted serum atenolol concentrations in most cats, with attendant HR reduction. Validation of these preliminary results in a larger sample and investigation of the treatment in cats with structural heart disease is needed. Verification of appropriate pH (target, 7.0) is likely essential for the compound's stability.

Comparison of left and right atrial volumes determined by two- and three-dimensional echocardiography with those determined by multidetector computed tomography for healthy dogs.

OBJECTIVE: To compare left atrial volume (LAV) and right atrial volume (RAV) determined by 2-D and 3-D echocardiographic methods with the LAV and RAV determined by ECG-gated multidetector CT (MDCT) for healthy dogs. ANIMALS: 11 healthy purpose-bred young adult hound-type dogs. PROCEDURES: Each dog was anesthetized and underwent MDCT and a complete echocardiographic examination. Modality-specific software was used to measure the respective atrial volumes at ventricular end systole, and LAV and RAV measurements were subsequently indexed to body weight and compared among imaging modalities. RESULTS: The LAV determined by echocardiographic methods did not differ significantly from the LAV determined by MDCT. However, the RAV determined by 3-D echocardiography and 2-D echocardiography via the left apical and left cranial windows differed significantly from the RAV determined by MDCT. Bland-Altman analyses indicated that the indexed LAV and RAV determined by echocardiographic methods were systematically underestimated, compared with MDCT measurements, but the bias was much smaller for LAV than for RAV. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that, for dogs, echocardiography might be an acceptable alternative to MDCT for measurement of LAV but not for measurement of RAV. However, the study population was small and homogenous in terms of breed, age, and weight. These findings need to be validated in a larger, more varied population of dogs with and without cardiac disease.

Effects of intravenous administration of tiletamine-zolazepam, alfaxalone, ketamine-diazepam, and propofol for induction of anesthesia on cardiorespiratory and metabolic variables in healthy dogs before and during anesthesia maintained with isoflurane.

OBJECTIVE To compare effects of tiletamine-zolazepam, alfaxalone, ketamine-diazepam, and propofol for anesthetic induction on cardiorespiratory and acid-base variables before and during isoflurane-maintained anesthesia in healthy dogs. ANIMALS 6 dogs. PROCEDURES Dogs were anesthetized with sevoflurane and instrumented. After dogs recovered from anesthesia, baseline values for cardiorespiratory variables and cardiac output were determined, and arterial and mixed-venous blood samples were obtained. Tiletamine-zolazepam (5 mg/kg), alfaxalone (4 mg/kg), propofol (6 mg/kg), or ketamine-diazepam (7 and 0.3 mg/kg) was administered IV in 25% increments to enable intubation. After induction (M0) and at 10, 20, 40, and 60 minutes of a light anesthetic plane maintained with isoflurane, measurements and sample collections were repeated. Cardiorespiratory and acid-base variables were compared with a repeated-measures ANOVA and post hoc t test and between time points with a pairwise Tukey test. RESULTS Mean ± SD intubation doses were 3.8 ± 0.8 mg/kg for tiletamine-zolazepam, 2.8 ± 0.3 mg/kg for alfaxalone, 6.1 ± 0.9 mg/kg and 0.26 ± 0.04 mg/kg for ketamine-diazepam, and 5.4 ± 1.1 mg/kg for propofol. Anesthetic depth was similar among regimens. At M0, heart rate increased by 94.9%, 74.7%, and 54.3% for tiletamine-zolazepam, ketamine-diazepam, and alfaxalone, respectively. Tiletamine-zolazepam caused higher oxygen delivery than propofol. Postinduction apnea occurred in 3 dogs when receiving alfaxalone. Acid-base variables remained within reference limits. CONCLUSIONS AND CLINICAL RELEVANCE In healthy dogs in which a light plane of anesthesia was maintained with isoflurane, cardiovascular and metabolic effects after induction with tiletamine-zolazepam were comparable to those after induction with alfaxalone and ketamine-diazepam.

Comparison of major complication and survival rates between surgical ligation and use of a canine ductal occluder device for treatment of dogs with left-to-right shunting patent ductus arteriosus.

OBJECTIVE To compare rates of major intraoperative complications and survival to hospital discharge between surgical ligation (SL) and canine ductal occluder (CDO) implantation for treatment of dogs with left-to-right shunting patent ductus arteriosus (PDA). DESIGN Retrospective cohort study. ANIMALS 120 client-owned dogs with left-to-right shunting PDA (62 treated by SL and 58 treated by CDO implantation). PROCEDURES Data were retrieved from medical records of included dogs regarding signalment, medical history, vertebral heart scale, preoperative echocardiographic findings, complications encountered during surgery, and durations of anesthesia and surgery (SL or CDO implantation). Data were compared between dogs treated by SL and those treated by CDO implantation. RESULTS Dogs treated by CDO implantation were significantly older and heavier than dogs treated by SL and had more pathological cardiac remodeling (as indicated by mitral regurgitation scores, left atrial-to-aortic root diameter ratios, and fractional shortening values). Durations of anesthesia and surgery were also significantly longer for CDO implantation versus SL. The major complication rate for dogs treated by SL (6/62 [10%]) was significantly greater than that for dogs treated by CDO implantation (0/58 [0%]). One dog in the SL group died during surgery. Overall rate of survival to hospital discharge was 99% (119/120). CONCLUSIONS AND CLINICAL RELEVANCE Both SL and CDO implantation were viable methods for PDA attenuation in the evaluated dogs. Although a greater proportion of dogs had major complications during the SL procedure, the 2 procedures had comparable rates of survival to hospital discharge.

Quantification of right ventricular volume measured by use of real-time three-dimensional echocardiography and electrocardiography-gated 64-slice multidetector computed tomography in healthy dogs.

OBJECTIVE To evaluate accuracy of quantification of right ventricle volume (RVV) by use of 3-D echocardiography (3DE) and ECG-gated multidetector CT (MDCT). ANIMALS 6 healthy hound-cross dogs. PROCEDURES ECG-gated MDCT and complete 3DE examinations were performed on each dog. Right ventricular end-diastolic volumes (EDVs), end-systolic volumes (ESVs), stroke volume (SV), and ejection fraction (EF) were measured for 3DE and MDCT data sets by use of software specific for RVV quantification. Correlation and level of agreement between methods were determined. Intraobserver and interobserver variability were assessed for 3DE. RESULTS No significant differences were detected between SV and EF obtained with MDCT and 3DE. Significant differences were detected between right ventricular EDV and ESV obtained with MDCT and 3DE. No significant difference in heart rate was detected between methods. The correlation between MDCT and 3DE was very good (r = 0.87) for EDV and ESV, moderate (r = 0.60) for EF, and poor (r = 0.31) for SV. Bland-Altman analysis revealed a systematic underestimation of RVV derived by use of 3DE, compared with the RVV derived by use of MDCT (mean bias, 15 and 10.3 mL for EDV and ESV, respectively). Intraobserver (EDV, 12%; ESV, 18%) and interobserver (EDV, 14%; ESV, 11%) variability were acceptable for 3DE. CONCLUSIONS AND CLINICAL RELEVANCE There was substantial variance for RVV measured by use of 3DE in healthy dogs and a significant underestimation of volumes, compared with results for MDCT, despite the fact there were no significant differences in SV and EF.

Cardiac output measured by use of electrocardiogram-gated 64-slice multidector computed tomography, echocardiography, and thermodilution in healthy dogs.

OBJECTIVE To evaluate the accuracy of cardiac output (CO) estimated by use of ECG-gated multidetector CT (MDCT) and 1-, 2-, and 3-D echocardiography and by use of thermodilution. ANIMALS 6 healthy hound-cross dogs. PROCEDURES Electrocardiogram-gated contrast-enhanced 64-slice MDCT and 1-, 2-, and 3-D echocardiography were performed on each dog. The CO for ECG-gated MDCT was calculated as volumetric measurements of stroke volume multiplied by mean heart rate. Echocardiographic left ventricle end-diastolic volumes and end-systolic volumes were measured by use of the Teichholz method (1-D echocardiography) and a single-plane method of disks (2-D echocardiography). Real-time 3-D echocardiographic left ventricle volumes were measured with 3-D functional analysis software on right long-axis and left apical views. The CO of each dog was measured in triplicate by use of thermodilution. Mean CO values, correlations, and limits of agreement for MDCT, echocardiographic modalities, and thermodilution were compared. RESULTS CO measured by use of MDCT, 2-D echocardiography, and 3-D echocardiography had the strongest correlations with CO measured by use of thermodilution. No significant difference in CO was detected between MDCT, any echocardiographic method, and thermodilution. Bland-Altman analysis revealed a systematic underestimation of CO derived by use of MDCT, 2-D echocardiography, and 3-D echocardiography. CONCLUSIONS AND CLINICAL RELEVANCE Use of MDCT, 2-D echocardiography, and 3-D echocardiography to measure CO in healthy dogs was feasible. Measures of CO determined by use of 3-D echocardiography on the right long-axis view were strongly correlated with CO determined by use of thermodilution, with little variance and slight underestimation.

Assessment of left ventricular volume and function in healthy dogs by use of one-, two-, and three-dimensional echocardiography versus multidetector computed tomography.

OBJECTIVE To compare left ventricle (LV) volume and function variables obtained by use of 1-D, 2-D, and real-time 3-D echocardiography versus ECG-gated multidetector row CT (MDCT) angiography, which was considered the criterion-referenced standard. ANIMALS 6 healthy, purpose-bred dogs. PROCEDURES Dogs were anesthetized and administered a constant rate infusion of esmolol, and 1-D, 2-D, and 3-D echocardiography and ECG-gated, contrast-enhanced MDCT were performed. End-diastolic volume (EDV), end-systolic volume (ESV), stroke volume, and ejection fraction (EF) were calculated by use of the Teichholz method for 1-D echocardiography, single-plane and biplane modified Simpson method of disks (MOD) and area-length method for 2-D echocardiography, and real-time biplane echocardiography (RTBPE) and real-time 3-D echocardiography (RT3DE) for 3-D echocardiography. Volumes were indexed to body surface area and body weight. Median values, correlations, and limits of agreement were compared between echocardiographic modalities and MDCT. RESULTS EDV and ESV measured by use of RTBPE and RT3DE had the strongest correlations with results for MDCT. Values obtained for EDV, ESV, stroke volume, and EF did not differ significantly between echocardiographic methods and MDCT. Use of RT3DE and RTBPE slightly underestimated EDV, ESV, and EF, compared with values for MDCT, as determined with Bland-Altman analysis. CONCLUSIONS AND CLINICAL RELEVANCE Values for EDV and ESV obtained by use of 3-D echocardiography, including RTBPE and RT3DE, had the highest correlation with slight underestimation, compared with values obtained by use of MDCT. This was similar to results for 3-D echocardiography in human medicine.

Biologic variability in NT-proBNP and cardiac troponin-I in healthy dogs and dogs with mitral valve degeneration.

BACKGROUND: The N-terminal fragment of the prohormone B-type natriuretic peptide (NT-proBNP) and cardiac troponin-I are candidate biomarkers for cardiac disease in dogs. The degree of biologic variation in these biomarkers has not previously been reported in healthy dogs or dogs with mitral regurgitation. OBJECTIVES: The purpose of the study was to derive estimates of intrinsic biologic variability and reference change values for NT-proBNP and cardiac troponin-I in healthy dogs and dogs with mitral regurgitation grade IB and II according to the International Small Animal Cardiac Health Council (ISACHC) grading system. METHODS: Plasma and sera were collected weekly for up to 7 weeks from 12 control dogs and 9 dogs with mitral regurgitation. NT-proBNP and troponin-I (C-TnI) concentrations were determined. Indices of biologic variation such as reciprocal index of individuality (r-IoI) and reference change values (RCV) were calculated in both the groups. RESULTS: Individuality was high in control dogs and dogs with grade IB and II mitral valve regurgitation for both C-TnI (r-IoI 1.6 and 2) and NT-proBNP (1.5 and 2.7), while the 2-sided RCV for NT-proBNP was significantly lower in dogs with mitral regurgitation (52.5% vs 99.4%, P<0.01.). CONCLUSIONS: High individuality of these cardiac biomarkers suggests that, following diagnosis, these assays are best interpreted by serial determination in individual canine patients rather than by comparison to a population-based reference interval. The smaller RCV values for dogs with mitral regurgitation suggest that smaller relative changes in NT-proBNP are clinically meaningful in these patients.

Long-term outcome of physiologic VDD pacing versus non-physiologic VVI pacing in dogs with high-grade atrioventricular block.

OBJECTIVE: To compare the long-term outcome associated with physiologic VDD and non-physiologic VVI or VVIR pacing in dogs with high-grade atrioventricular block. ANIMALS: Forty-nine paced dogs with high-grade atrioventricular block were included. METHODS: Retrospective review of medical records, thoracic radiographs and echocardiograms for all dogs. Patient owners and referring veterinarians were contacted for survival times and a satisfaction questionnaire was submitted to the owners. Survival times, complication rates, resolution of clinical signs, and owner satisfaction were compared between the pacing modalities. RESULTS: A single lead VDD pacemaker was implanted in 19 dogs (39%) whereas 30 dogs (61%) were treated with VVI pacing. The median survival time for all dogs post-pacemaker implantation was 24.5 months. Survival time was significantly decreased in dogs that were older at the time of presentation or that presented with ventricular tachycardia or reduced left ventricular fractional shortening. Median survival times after implantation were not significantly different between pacing modalities (P = 0.29). Major complication rates were 11% within the VDD group and 20% within the VVI group and were not significantly different (P = 0.46). Minor complications were significantly higher within the VDD group than within the VVI group (47% versus 7% respectively; P < 0.01) due to a higher number of dogs in the VDD group experiencing transient ventricular premature contractions in the immediate post-implantation time period. Resolution of clinical signs, owner satisfaction, and quality of life perception were considered excellent in both groups. CONCLUSIONS: No long-term clinical benefit of VDD over VVI pacing could be identified in the present study.

Bacterial pericarditis in a cat.

CASE SUMMARY: A 4-year-old male neutered domestic shorthair cat was presented to the Oregon State University cardiology service for suspected pericardial effusion. Cardiac tamponade was documented and pericardiocentesis yielded purulent fluid with cytologic results supportive of bacterial pericarditis. The microbial population consisted of Pasteurella multocida, Actinomyces canis, Fusobacterium and Bacteroides species. Conservative management was elected consisting of intravenous antibiotic therapy with ampicillin sodium/sulbactam sodium and metronidazole for 48 h followed by 4 weeks of oral antibiotics. Re-examination 3 months after the initial incident indicated no recurrence of effusion and the cat remained free of clinical signs 2 years after presentation. RELEVANCE AND NOVEL INFORMATION: Bacterial pericarditis is a rare cause of pericardial effusion in cats. Growth of P multocida, A canis, Fusobacterium and Bacteroides species has not previously been documented in feline septic pericarditis. Conservative management with broad-spectrum antibiotics may be considered when further diagnostic imaging or exploratory surgery to search for a primary nidus of infection is not feasible or elected.

Multi-detector computed tomography of an aortic dissection in a cat.

Contrast enhanced, multi-detector computed tomography (MDCT) is a useful diagnostic imaging modality that has become increasingly available in veterinary medicine. Multi-planar and three-dimensional reconstructions allow accurate and comprehensive assessment of cardiac and vascular lesions with short image acquisition times. ECG-gated, contrast enhanced MDCT was used to assess the lesion extent and therapeutic options in a case of aortic dissection diagnosed in a hypertensive cat.

Transvenous extraction of an abandoned endocardial pacemaker lead in a dog.

A 6-year-old male castrated labrador retriever presented with endocardial pacemaker infection following migration and subsequent repositioning of the pulse generator. An epicardial lead and pulse generator were surgically implanted and the endocardial lead could not be removed with manual traction. The endocardial lead was severed, anchored, and abandoned at the thoracic inlet. The patient presented 4 months later with endocardial lead migration, bacteremia, and suspected glomerulonephritis. The endocardial pacemaker lead was transvenously extracted using a mechanical dilator sheath and locking stylet. This report of transvenous pacemaker lead extraction in a dog addresses the challenges and describes recent advances in extraction devices.

Validation of a commercially available enzyme immunoassay for measurement of plasma antidiuretic hormone concentration in healthy dogs and assessment of plasma antidiuretic hormone concentration in dogs with congestive heart failure.

OBJECTIVE: To validate the use of a human enzyme immunoassay (EIA) kit for measurement of plasma antidiuretic hormone (ADH) concentration in dogs and evaluate plasma ADH concentrations in dogs with congestive heart failure (CHF) attributable to acquired cardiac disease, compared with findings in healthy dogs. ANIMALS: 6 healthy dogs and 12 dogs with CHF as a result of chronic degenerative valve disease or dilated cardiomyopathy. PROCEDURES: Plasma samples from the 6 healthy dogs were pooled and used to validate the EIA kit for measurement of plasma ADH concentration in dogs by assessing intra-assay precision, dilutional linearity, and spiking recovery. Following validation, plasma ADH concentrations were measured in the 6 healthy dogs and in the 12 dogs with CHF for comparison. RESULTS: The EIA kit measured ADH concentrations in canine plasma samples with acceptable intra-assay precision, dilutional linearity, and spiking recovery. The intra-assay coefficient of variation was 11%. By use of this assay, the median plasma concentration of ADH in dogs with CHF was 6.15 pg/mL (SD, 3.2 pg/mL; range, 4.18 to 15.47 pg/mL), which was significantly higher than the median concentration in healthy dogs (3.67 pg/mL [SD, 0.93 pg/mL; range, 3.49 to 5.45 pg/mL]). CONCLUSIONS AND CLINICAL RELEVANCE: Plasma ADH concentrations in dogs can be measured with the tested EIA kit. Plasma ADH concentrations were higher in dogs with CHF induced by acquired cardiac disease than in healthy dogs. This observation provides a basis for future studies evaluating circulating ADH concentrations in dogs with developing heart failure.

Anomalous left-to-right shunting communication between the ascending aorta and right pulmonary artery in a dog.

Anomalies of conotruncal septation are rare in dogs and uncommon in humans. Congenital conotruncal defects most commonly reported in veterinary medicine include aorto-pulmonary window and persistent truncus arteriosus. We report a case of an anomalous vessel connecting the ascending aorta to the right pulmonary artery causing left-to-right shunting, left-sided volume overload, and pulmonary overcirculation. Transesophageal echocardiography, cardiac catheterization, and contrast-enhanced computed tomography assisted in the diagnosis and facilitated the surgical correction of the anomalous vessel. The authors hypothesize this defect represents an unusual anomalous vessel connecting the ascending aorta to the right pulmonary artery.