Barret J. Bulmer

Echocardiographic estimation of mean left atrial pressure in a canine model of acute mitral valve insufficiency.

High mean left atrial pressure (MLAP) due to canine degenerative mitral valve disease is associated with clinically relevant morbidity and mortality. The ability to noninvasively measure MLAP would assist in the diagnosis and treatment of disease. Doppler echocardiography allows measurement of early transmitral blood flow (E) and the velocity of the mitral valve annulus (Ea). The ratio of early mitral inflow velocity to early mitral annular velocity (E: Ea) correlates well with MLAP in human subjects. We sought to determine the ability of E: Ea to predict MLAP in dogs with experimentally induced mitral regurgitation. Nine anesthetized purpose-bred dogs underwent placement of a Swan-Ganz catheter into the left atrium and recording of MLAP. Simultaneous transthoracic echocardiographic and hemodynamic studies were performed after acute chordae tendineae rupture and during IV infusion with nitroprusside (2.5-5.0 microg x kg(-1) x min(-1)) or hydralazine (1-1.5 mg/kg). Mitral regurgitant fraction, measured by single-plane angiography and thermodilution, ranged from 17% to 81%. MLAP increased from 5.4 +/- 2.5 mm Hg to 17.4 +/- 9.4 mm Hg after creation of mitral valve regurgitation (MR; P = .018). Forty sets of echocardiographic measurements were obtained from 7 dogs, and E, as well as E: Ea, were linearly related to MLAP. The R2 value for the linear regression equation containing E: Ea as the dependent variable (0.83) was greater than that for E (0.73). The 95% confidence intervals were calculated for predicting MLAP = 20 mm Hg from E:Ea, and E:Ea >9.1 or <6.0 indicated a 95% probability that MLAP was >20 mm Hg or <20 mm Hg, respectively. Echocardiography can be used to predict MLAP in isoflurane-anesthetized dogs with experimentally induced acute mitral valve insufficiency.

Assessment of serum N-terminal pro-B-type natriuretic peptide concentration for differentiation of congestive heart failure from primary respiratory tract disease as the cause of respiratory signs in dogs

OBJECTIVE To determine whether serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) concentration is useful in discriminating between cardiac and noncardiac (ie, primary respiratory tract disease) causes of respiratory signs (ie, coughing, stertor, stridor, excessive panting, increased respiratory effort, tachypnea, or overt respiratory distress) in dogs. DESIGN Multicenter cross-sectional study. ANIMALS P 115 dogs with respiratory signs. PROCEDURES Dogs with respiratory signs were solicited for study. Physical examination, thoracic radiography, and echocardiography were used to determine whether respiratory signs were the result of cardiac (ie, congestive heart failure) or noncardiac (ie, primary respiratory tract disease) causes. Serum samples for NT-proBNP assay were obtained at time of admission for each dog. Receiver-operating characteristic curves were constructed to determine the ability of serum NT-proBNP concentration to discriminate between cardiac and noncardiac causes of respiratory signs. RESULTS Serum NT-proBNP concentration was significantly higher in dogs with cardiac versus noncardiac causes of respiratory signs. In dogs with primary respiratory tract disease, serum NT-proBNP concentration was significantly higher in those with concurrent pulmonary hypertension than in those without. A serum NT-proBNP cutoff concentration > 1,158 pmol/L discriminated between dogs with congestive heart failure and dogs with primary respiratory tract disease with a sensitivity of 85.5% and a specificity of 81.3%. CONCLUSIONS AND CLINICAL RELEVANCE Measuring serum NT-proBNP concentration in dogs with respiratory signs helps to differentiate between congestive heart failure and primary respiratory tract disease as an underlying cause.

Comparison of complications of percutaneous endoscopic versus surgically placed gastrostomy tubes in 42 dogs and 52 cats.

Dogs and cats that had a percutaneous endoscopic gastrostomy (PEG) tube or surgically placed gastrostomy (SPG) tube inserted were retrospectively analyzed to compare complication rates and the severity of complications. Complication rates and severity scores were not significantly different when the PEG tube group was compared to the SPG tube group in either dogs or cats. Only when data from dogs and cats were combined did PEG tubes have a significantly higher complication rate and significantly greater complication severity scores.

Physiologic VDD versus nonphysiologic VVI pacing in canine 3rd-degree atrioventricular block.

Historically, ventricular demand, nonphysiologic (VVI) pacing has been the most commonly used modality to treat 3rd-degree atrioventricular (AV) block. The goal of this study was to determine the feasibility of using a commercial, single-lead, physiologic (VDD) pacemaker in dogs with 3rd-degree AV block. Furthermore, we hoped to characterize and identify differences in the radiographic, echocardiographic, neurohormonal, and quality of life consequences of physiologic versus nonphysiologic pacing. We evaluated 10 dogs during a 12-week crossover study. Acutely, rate-matched physiologic pacing reduced pulmonary capillary wedge pressure by 19% compared with nonphysiologic pacing. VDD pacing significantly reduced left atrial size normalized to body weight, left atrial-to-aortic root ratio, and left ventricular end-systolic dimension and increased fractional shortening, aortic Doppler velocity, cardiac output, and stroke volume compared with VVI pacing. Variable rate VDD pacing resulted in a significantly slower heart rate (HR) during echocardiography than fixed-rate (100 bpm) VVI pacing. AV synchronous pacing reduced circulating N-terminal proatrial natriuretic peptide (ANP), norepinephrine (NOR), and epinephrine (EPI) concentrations compared with asynchronous pacing. There were no significant differences in systemic blood pressure, thoracic radiographs, or owner-perceived quality of life. The median percentage of AV synchronous pacing during the VDD modality was 99.8% (range, 1.2 to 99.9%). This study confirms the potential to achieve physiologic pacing with a commercial, single-lead system in dogs. VDD pacing improved hemodynamics and neurohormonal profiles over asynchronous pacing although the long-term clinical benefits of these changes remain to be determined.

Cardiovascular Dysfunction in Sepsis and Critical Illness

Myocardial dysfunction is commonly encountered in humans, and presumably in dogs with sepsis and critical illness. This dysfunction contributes to increased mortality. With management of the underlying diseases and an understanding of the processes contributing to myocardial dysfunction, steps may be taken to mitigate the consequences of cardiac impairment. Clinical findings, proposed pathophysiologic mechanisms, and current treatment considerations are discussed. Further study is needed to find practical ways to identify myocardial dysfunction and to determine whether timed interventions intended to augment cardiac performance will reduce mortality in this patient population.

Evaluation of a training course in focused echocardiography for noncardiology house officers

Objective To determine whether a training course in focused echocardiography can improve the proficiency of noncardiology house officers in accurately interpreting cardiovascular disease and echocardiography findings in dogs entering the emergency room setting. Design Prospective, blinded, educational study. Setting University veterinary teaching hospital. Study Subjects House officers underwent training in focused echocardiography. Fifteen dogs, including normal dogs and dogs with stable congenital or acquired cardiac disease, were used as study subjects during the laboratory session. Interventions A 6-hour curriculum on focused echocardiography was developed that included didactic lectures, clinical cases, and hands-on echocardiography. Measurements and Main Results Pre- and postcourse written examinations were administered to participants. House officers attended didactic lectures that were subsequently followed by a hands-on laboratory session and practical examination, which involved performing transthoracic echocardiography on dogs with and without cardiovascular disease. Twenty-one house officers completed the focused echocardiography training course. Written examination scores were 57 ± 12% before and 75 ± 10% after training (P 6 hours. Conclusion A focused echocardiography training course improved knowledge and yielded acceptable proficiency in some echocardiographic findings commonly identified in the emergency room. This training course was not able to provide the skills needed for house officers to accurately assess fluid volume status, identify cardiac masses, ventricular enlargement or hypertrophy, and certain cardiac diseases.OBJECTIVE To determine whether a training course in focused echocardiography can improve the proficiency of noncardiology house officers in accurately interpreting cardiovascular disease and echocardiography findings in dogs entering the emergency room setting. DESIGN Prospective, blinded, educational study. SETTING University veterinary teaching hospital. STUDY SUBJECTS House officers underwent training in focused echocardiography. Fifteen dogs, including normal dogs and dogs with stable congenital or acquired cardiac disease, were used as study subjects during the laboratory session. INTERVENTIONS A 6-hour curriculum on focused echocardiography was developed that included didactic lectures, clinical cases, and hands-on echocardiography. MEASUREMENTS AND MAIN RESULTS Pre- and postcourse written examinations were administered to participants. House officers attended didactic lectures that were subsequently followed by a hands-on laboratory session and practical examination, which involved performing transthoracic echocardiography on dogs with and without cardiovascular disease. Twenty-one house officers completed the focused echocardiography training course. Written examination scores were 57 ± 12% before and 75 ± 10% after training (P < 0.001). Following the course, 97% of participants in the practical examination were able to obtain the correct right parasternal short- or long-axis view. Posttraining, most participants correctly identified pleural effusion (90%) and pericardial effusion (95%) and discriminated normal atrial size from atrial enlargement (86%). However, successful identification of a cardiac mass, volume status, and ability to recognize a poor quality study as nondiagnostic remained relatively low. Most trainees responded that the length of hands-on laboratory training was too abbreviated and that the course should be > 6 hours. CONCLUSION A focused echocardiography training course improved knowledge and yielded acceptable proficiency in some echocardiographic findings commonly identified in the emergency room. This training course was not able to provide the skills needed for house officers to accurately assess fluid volume status, identify cardiac masses, ventricular enlargement or hypertrophy, and certain cardiac diseases.

Body size and metabolic differences in Maine Coon cats with and without hypertrophic cardiomyopathy

An interplay between growth, glucose regulation and hypertrophic cardiomyopathy (HCM) may exist, but has not been studied in detail. The purpose of this study was to characterize morphometric features, insulin-like growth factor-1 (IGF-1) and glucose metabolism in Maine Coon cats with HCM. Body weight, body condition score (BCS), head length and width, and abdominal circumference were measured in Maine Coon cats >2 years of age. Echocardiography and thoracic radiography (for measurement of humerus length, and fourth and twelfth vertebrae length) were also performed. Blood was collected for biochemistry profile, DNA testing, insulin and IGF-1. Sixteen of 63 cats had HCM [myosin binding protein C (MYBPC)+, n = 3 and MYBPC−, n = 13] and 47/63 were echocardiographically normal (MYBPC+, n = 17 and MYBPC−, n = 30). There were no significant differences in any measured parameter between MYBPC+ and MYBPC− cats. Cats with HCM were significantly older (P <0.001), heavier (P = 0.006), more obese (P = 0.008), and had longer humeri (P = 0.02) compared with the HCM− group. Cats with HCM also had higher serum glucose (P = 0.01), homeostasis model assessment (HOMA) and IGF-1 (P = 0.01) concentrations, were from smaller litters (P = 0.04), and were larger at 6 months (P = 0.02) and at 1 year of age (P = 0.03). Multivariate analysis revealed that age (P <0.001), BCS (P = 0.03) and HOMA (P = 0.047) remained significantly associated with HCM. These results support the hypothesis that early growth and nutrition, larger body size and obesity may be environmental modifiers of genetic predisposition to HCM. Further studies are warranted to evaluate the effects of early nutrition on the phenotypic expression of HCM.

Auscultatory, echocardiographic, biochemical, nutritional, and environmental characteristics of mitral valve disease in Norfolk terriers.

OBJECTIVES In order to more fully understand degenerative mitral valve disease (DMVD) in the Norfolk terrier, we sought to characterize findings from the physical and echocardiographic examination; biochemical, biomarker, and nutritional profiles; and select environmental variables from a cohort of apparently healthy Norfolk terriers. ANIMALS, MATERIALS AND METHODS Overtly healthy Norfolk terriers ≥ 6 yrs old were recruited by 3 different veterinary hospitals and underwent historical, physical, electrocardiographic (ECG), and 2D/color-flow Doppler echocardiographic examinations. Anterior mitral valve leaflet length, maximal thickness, area, and degree of prolapse were measured or calculated from two-dimensional images. Blood samples were obtained for serum biochemistry, serum serotonin, plasma NT-proBNP, amino acid profile, C-reactive protein, and cardiac troponin I. RESULTS Of the 48 dogs entered into the study, 23 (48%) had murmurs, 2 (4%) had mid-systolic clicks, 11 (23%) had ECG P pulmonale, and 41 (85%) were deemed to have echocardiographic evidence of DMVD, including 18 Norfolk terriers without a murmur. Seven (15%), 28 (58%), and 13 (27%) dogs were classified as normal (stage 0), International Small Animal Cardiac Health Council (ISACHC) stage 1a, and 1b, respectively. Mean indexed echocardiographic mitral leaflet thickness (P = 0.017), area (P = 0.0002), prolapse (P = 0.0004), and left atrial to aortic diameter (P = 0.01) were significantly different between ISACHC 0, 1a, and 1b. CONCLUSION DMVD is relatively common in Norfolk terriers and echocardiographic changes consistent with mild DMVD can be seen in dogs without a heart murmur.

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.