International collaborative study to assess cardiovascular risk and evaluate long-term health in cats with preclinical hypertrophic cardiomyopathy and apparently healthy cats: The REVEAL Study.

BACKGROUND: Hypertrophic cardiomyopathy is the most prevalent heart disorder in cats and principal cause of cardiovascular morbidity and mortality. Yet, the impact of preclinical disease is unresolved. HYPOTHESIS/OBJECTIVES: Observational study to characterize cardiovascular morbidity and survival in cats with preclinical nonobstructive (HCM) and obstructive (HOCM) hypertrophic cardiomyopathy and in apparently healthy cats (AH). ANIMALS: One thousand seven hundred and thirty client-owned cats (430 preclinical HCM; 578 preclinical HOCM; 722 AH). METHODS: Retrospective multicenter, longitudinal, cohort study. Cats from 21 countries were followed through medical record review and owner or referring veterinarian interviews. Data were analyzed to compare long-term outcomes, incidence, and risk for congestive heart failure (CHF), arterial thromboembolism (ATE), and cardiovascular death. RESULTS: During the study period, CHF, ATE, or both occurred in 30.5% and cardiovascular death in 27.9% of 1008 HCM/HOCM cats. Risk assessed at 1, 5, and 10 years after study entry was 7.0%/3.5%, 19.9%/9.7%, and 23.9%/11.3% for CHF/ATE, and 6.7%, 22.8%, and 28.3% for cardiovascular death, respectively. There were no statistically significant differences between HOCM compared with HCM for cardiovascular morbidity or mortality, time from diagnosis to development of morbidity, or cardiovascular survival. Cats that developed cardiovascular morbidity had short survival (mean ± standard deviation, 1.3 ± 1.7 years). Overall, prolonged longevity was recorded in a minority of preclinical HCM/HOCM cats with 10% reaching 9-15 years. CONCLUSIONS AND CLINICAL IMPORTANCE: Preclinical HCM/HOCM is a global health problem of cats that carries substantial risk for CHF, ATE, and cardiovascular death. This finding underscores the need to identify therapies and monitoring strategies that decrease morbidity and mortality.

Pharmacokinetics and pharmacodynamics of the factor Xa inhibitor apixaban after oral and intravenous administration to cats.

OBJECTIVE: To determine pharmacokinetic and pharmacodynamic properties of the novel factor Xa inhibitor apixaban in clinically normal cats. ANIMALS: 5 purpose-bred domestic shorthair cats. PROCEDURES: A single dose of apixaban (0.2 mg/kg, PO) was administered to each cat (time 0), and blood samples were obtained at 0, 15, 30, 45, 60, 120, 240, 360, 480, and 1,440 minutes. After a 1-week washout period, another dose of apixaban (0.2 mg/kg, IV) was administered to each cat, and blood samples were obtained at 0, 5, 10, 15, 30, 45, 60, 120, 240, 360, 480, and 1,440 minutes. Apixaban concentrations in plasma were measured via liquid chromatography-tandem mass spectrometry. Pharmacodynamic effects of apixaban were determined with a commercial assay for factor × activity, which measures endogenous factor Xa activity chromogenically. RESULTS: Factor Xa was inhibited as a function of time after a single dose of apixaban administered orally or IV, and a direct inverse correlation with the plasma apixaban concentration was detected. Pharmacokinetic analysis revealed moderate clearance, short half-life, and high bioavailability for apixaban. A 2-compartment model was fit to the IV pharmacokinetic data; compartmental modeling could not be used to adequately describe the oral data because of substantial interindividual variability. CONCLUSIONS AND CLINICAL RELEVANCE: Results inticated that apixaban was an effective inhibitor of factor Xa in cats. Further studies will be needed to determine pharmacokinetics and pharmacodynamics after multidose administration, effects of cardiac disease on pharmacokinetics and pharmacodynamics, dosing recommendations, and efficacy of apixaban for use in the treatment and prevention of thromboembolic disease in cats.

Pulmonary artery dissection in eight dogs with patent ductus arteriosus.

OBJECTIVES: To describe a series of dogs with pulmonary artery dissection and patent ductus arteriosus (PDA). ANIMALS: Eight dogs. METHODS: Retrospective case series. RESULTS: Pulmonary artery dissection was diagnosed in 8 dogs, 3 were Weimaraners. Four dogs presented in left-sided congestive heart failure, 4 presented for murmur evaluation and without clinical signs, and 1 presented in right-sided congestive heart failure. In 7 dogs the dissection was first documented concurrent with a diagnosis of uncorrected PDA. In the other dog, with pulmonary valve stenosis and PDA, the dissection was observed on autopsy examination 17 months after balloon pulmonary valvuloplasty and ductal closure. Median age at presentation for the 7 dogs with antemortem diagnosis of pulmonary artery dissection was 3.5 years (range, 1.5-4 years). Three dogs had the PDA surgically ligated, 2 dogs did not undergo PDA closure, 1 dog failed transcatheter occlusion of the PDA with subsequent surgical ligation, 1 dog underwent successful transcatheter device occlusion of the PDA, and 1 dog had the PDA closed by transcatheter coil delivery 17 months prior to the diagnosis of pulmonary artery dissection. The 2 dogs that did not have the PDA closed died 1 and 3 years after diagnosis due to heart failure. CONCLUSIONS: Pulmonary artery dissection is a potential complication of PDA in dogs, the Weimaraner breed may be at increased risk, presentation is often in mature dogs, and closure of the PDA can be performed and appears to improve outcome.

An echocardiographic study of healthy Border Collies with normal reference ranges for the breed.

OBJECTIVES: The objectives of this study were to obtain standard echocardiographic measurements from healthy Border Collies and to compare these measurements to those previously reported for a general population of dogs. ANIMALS: Standard echocardiographic data were obtained from twenty apparently healthy Border Collie dogs. These data (n = 20) were compared to data obtained from a general population of healthy dogs (n = 69). METHODS: Border Collies were deemed healthy based on normal history, physical examination, complete blood count, serum biochemical profile, electrocardiogram, and blood pressure, with no evidence of congenital or acquired heart disease on echocardiographic examination. Standard two dimensional, M-mode, and Doppler echocardiographic measurements were obtained and normal ranges determined. The data were compared to data previously obtained at our hospital from a general population of normal dogs. RESULTS: Two dimensional, M-mode, and Doppler reference ranges for healthy Border Collies are presented in tabular form. Comparison of the weight adjusted M-mode echocardiographic means from Border Collies to those from the general population of dogs showed Border Collies to have larger left ventricular systolic and diastolic dimensions, smaller interventricular septal thickness, and lower fractional shortening. CONCLUSIONS: There are differences in some echocardiographic parameters between healthy Border Collies and the general dog population, and the echocardiographic reference ranges provided in this study should be used as breed specific reference values for Border Collies.

Thrombotic complications associated with atrial fibrillation in three dogs.

Atrial fibrillation (AF) is the most common chronic pathologic arrhythmia in dogs, and whereas thromboembolism is a common complication of AF in humans, this complication has not been previously reported in dogs. This report describes thrombotic complications associated with AF in three dogs. A spherical left atrial mass consistent with a thrombus was identified in two dogs during echocardiographic examination. A third dog experienced arterial thromboembolism confirmed with ultrasound and postmortem examination. These cases provide a unique antemortem description of intra-atrial thrombus formation and cardioembolic disease associated with AF in dogs, and raise awareness of the importance of thorough echocardiographic evaluation of the atria for thrombus prior to pharmacologic cardioversion or direct current cardioversion.

Doppler echocardiographic description of double-inlet left ventricle in an Arabian horse.

Univentricular atrioventricular (AV) connections are rare and complex congenital cardiac anomalies in which both AV valves communicate into a large, common (single) receiving chamber. The common chamber can be of left, right, or mixed ventricular morphology. Although well documented in people, reports of the double-inlet ventricle malformation are rare in the veterinary literature. This report provides description of an Arabian horse with a double-inlet univentricular connection of left ventricular type, a hypoplastic subpulmonary right ventricle, two muscular ventricular septal defects, and a stenotic mitral valve. Transthoracic Doppler echocardiography enabled antemortem diagnosis, and provided an assessment of intracardiac hemodynamics. The findings indicate that Doppler echocardiography is a useful, noninvasive tool for evaluating equine patients with congenital univentricular AV connections, such as a double-inlet left ventricle.

Transvenous occlusion of patent ductus arteriosus in 56 consecutive dogs.

OBJECTIVE: Document safety and efficacy of transvenous catheter occlusion of patent ductus arteriosus (PDA) over a wide range of ductal and patient sizes. ANIMALS, MATERIALS AND METHODS: Retrospective study of fifty-six consecutive dogs referred to Colorado State University with diagnosis of PDA. All cases utilized the transvenous approach, via the femoral vein. Occlusion was achieved using a coil (Flipper) in dogs with PDA minimal dimension of 4 mm, or if a coil was unstable following deployment. RESULTS: Ductal occlusion was achieved using the transvenous route alone in 54/56 dogs (96.4%). Occlusion was achieved using detachable Flipper coils in 39/42 dogs (92.9%) in which coil occlusion was attempted, with 38/39 dogs (97.4%) requiring only a single coil. In 16 dogs, occlusion was achieved using an Amplatzer duct occluder or vascular plug. Post-procedure residual ductal flow was absent or only mild in 36/39 (92.3%) dogs in which it was assessed. Procedural mortality rate was 1.7%, and major complication rate 7.0%. CONCLUSION: Transcatheter occlusion via a transvenous approach is a safe and effective method for treating PDA in dogs and is useful for small dogs (<2.5 kg).

Chronic cardiac tamponade in a cat caused by an intrapericardial biliary cyst.

A 1-year-old domestic longhair cat presented to our hospital with a 4-month history of progressive exercise intolerance and coughing. Two-dimensional echocardiography confirmed the presence of an intrapericardial cyst and cardiac tamponade. Tamponade was relieved via percutaneous aspiration of the cyst. The cyst was surgically excised 4 days later, and histopathology was consistent with a biliary cyst. The cat's clinical signs completely resolved following surgery.

Successful biphasic transthoracic defibrillation of a dog with prolonged, refractory ventricular fibrillation.

OBJECTIVE: To describe a case of spontaneous ventricular fibrillation in a dog in which biphasic defibrillation was life saving. CASE SUMMARY: Ventricular fibrillation occurred in a 7-year-old female Australian Heeler during recovery from anesthesia following pacemaker implantation. Resuscitative efforts including immediate delivery of transthoracic monophasic defibrillation shocks of escalating energy and administration of vasopressors were unsuccessful. However, a single biphasic shock restored sinus rhythm despite prolonged duration of the arrhythmia. NEW OR UNIQUE INFORMATION PROVIDED: This case suggests greater efficacy of biphasic defibrillation compared with traditional monophasic defibrillation. In this dog the newer, biphasic technology was life saving after monophasic shocks failed repeatedly to terminate ventricular fibrillation.

Chronic cor pulmonale secondary to pulmonary atherosclerosis in an African Grey parrot.

CASE DESCRIPTION: A 20-year-old sexually intact female African Grey parrot (Psittacus erithacus) was evaluated to determine the cause of lethargy, hyporexia, weight loss, and persistent ascites of 21 days' duration. CLINICAL FINDINGS: Physical examination revealed a markedly distended abdomen and systolic heart murmur. Thoracic radiography revealed cardiomegaly and hepatomegaly. Doppler echocardiography revealed severe eccentric and concentric hypertrophy of the right ventricle with systolic dysfunction, moderate regurgitation through the right atrioventricular valve, a substantial increase in estimated systolic pulmonary arterial pressure, hepatic venous congestion, and coelomic effusion. A clinical diagnosis of chronic cor pulmonale was established. TREATMENT AND OUTCOME: The parrot was initially stabilized by use of coelomocentesis. During the next month, the parrot was treated by administration of furosemide, hydrochlorothiazide, spironolactone, benazepril, and pimobendan. The parrot appeared to be responding well to treatment but was found dead in its cage 35 days following initial examination. Postmortem examination revealed substantial atherosclerosis of the large pulmonary arteries, with lesions extending into the medium-size arteries. Pulmonary atherosclerosis was suspected as a cause of the severe pulmonary hypertension. CLINICAL RELEVANCE: Although atherosclerosis most commonly affects the systemic and coronary arteries of parrots, sclerotic changes within the pulmonary vasculature should be considered as a possible cause of pulmonary hypertension and as a differential diagnosis for right-sided congestive heart failure in psittacine species.

The effects of age and heart rate on tricuspid annular motion velocities in healthy nonsedated cats.

BACKGROUND: Age and heart rate have effects on myocardial velocities as assessed by color tissue Doppler imaging (TDI) in people. A similar phenomenon has been identified when left ventricular velocities are assessed in cats. To date, the effects of age and heart rate on tricuspid annular velocities of cats have not been assessed. OBJECTIVES: This study was designed to determine the relationships between age and heart rate and tricuspid annular velocities in cats as assessed by 2-dimensional (2D) color TDI. ANIMALS: Fifty healthy nonsedated cats with age range from 3 months to 19 years old were studied. METHODS: Tricuspid annular velocities were obtained with 2D color TDI. Effects of age and heart rate on tricuspid annular velocities were evaluated by simple linear regression. The strength of the linear relationship was determined by using coefficient of determination (R2). RESULTS: A significant weak negative relationship was found between age and peak early diastolic annular velocity (E'; R2 = 0.135, P = .018). No significant relationships between age and right ventricular (RV) systolic TDI values were found. Diastolic and systolic TDI parameters were not affected by heart rate with the exception of deceleration rate of early diastolic motion (DR; R2 = 0.100, P = .025). CONCLUSIONS AND CLINICAL IMPORTANCE: Age and heart rate have minimal effects on tricuspid annular velocities. The present study provides reference ranges for tricuspid annular velocities in healthy cats and information for assessing the clinical utility of color TDI for evaluation of RV function in cats.

Percutaneous selective pulmonary artery bands (Joeys) in a pulmonary overcirculation model.

BACKGROUND: Control of distal pulmonary artery (PA) pressure and flow is a critical step in palliating infants with complex congential heart disease. Surgical procedures to protect or isolate the pulmonary circulation carry significant risk and can be unpredictable. Interventional control of pulmonary pressure/flow with an intravascular device (band) could reduce risk and improve regulation of pulmonary flow. METHODS: Internal pulmonary bands were created from woven nitinol to create an internal orifice estimated to reduce distal pulmonary arterial pressure by 50%. Two designs were tested, a single eccentric lumen and two symmetrical lumens. The devices were approximately 7-mm long and the external diameter varied to suit the pulmonary arterial lumen size. A total of 15 devices were implanted in seven lambs with a stented ductus arteriosus to create high pulmonary pressure/flow. Four lambs were followed with devices and stent in place for a mean of 37 +/- 13 days. RESULTS: Fourteen of 15 devices were successfully implanted. One was acutely removed since the size was too large. Both device designs created greater than a 50% reduction in distal pulmonary pressure. Main PA pressure was 70/38, mean 50 +/- 13 mm Hg, and distal PA pressure 25/16, mean 20 +/- 7 mm Hg (P < 0.05). Angiography demonstrated protection of the internal banded pulmonary segments from overcirculation. Late follow-up showed that the device lumen(s) remained patent. Histology showed the vessel media to be intact but there was intimal proliferation where the device approximated the wall. There were no thrombotic emboli detected. CONCLUSION: Percutaneous internal banding of the pulmonary arteries was feasible and successful in lambs with high pulmonary flow/pressure analogous to infants with complex congenital heart disease.

Cardiovascular involvement in 8 dogs with blastomyces dermatitidis infection.

BACKGROUND: Blastomycosis is a common systemic fungal infection in dogs. HYPOTHESIS: Dogs with cardiovascular involvement may have abnormalities in electrical conduction and valvular function, and may have a worse prognosis. ANIMALS: Eight client-owned animals. METHODS: Dogs with cardiovascular lesions caused by blastomycosis were identified from retrospective evaluation of medical records. RESULTS: Five dogs had de novo infections and 3 had recurrences of previously treated infections. Harsh labored breathing, lethargy, and anorexia were the most common historic complaints. Three dogs had syncope. Physical examination and clinicopathologic data were typical of blastomycosis and included dyspnea, increased lung sounds, and lethargy. In addition, 3 dogs had heart murmurs and 1 had a third-degree atrioventricular block. Four dogs had myocarditis and 2 had pericarditis or epicarditis. Two dogs had cardiac signs attributed to extracardiac compression by fungal granulomas and clinical signs were relieved by treatment. Half of the remaining 6 dogs were euthanized; 2 of these were not treated. Of the remaining 3 dogs, 1 dog died acutely while sleeping; the second died intraoperatively during an attempt to place an epicardial pacemaker; and the third had Blastomyces-induced endocarditis and died of heart failure. CONCLUSIONS AND CLINICAL IMPORTANCE: Blastomycosis should be considered in the differential diagnosis of dogs from endemic areas with inflammatory myocarditis, heart block, heart base or intracardiac mass lesions, syncope, or endocarditis.

Transcatheter intravascular stent placement to relieve supravalvular pulmonic stenosis.

Valvular pulmonic stenosis has been successfully treated in dogs via minimally invasive transcatheter balloon dilation procedures for almost 20years. Supravalvular pulmonic stenosis however is not amenable to balloon dilation procedures. Although several surgical procedures are described for treatment of pulmonic stenosis, the morbidity and mortality of these procedures are significantly higher than for transcatheter approaches. Two cases of supravalvular pulmonic stenosis are presented, one acquired and one congenital, which were successfully treated with transcatheter intravascular stent placement. The procedure alleviated the stenotic lesion and resolved clinical signs.

Web-based technology: its effects on small group "problem-based learning" interactions in a professional veterinary medical program.

The objective of this investigation was to ascertain whether and how the introduction of a new technology (WebCT) influenced faculty teaching styles while facilitating small group problem-based learning (PBL) sessions in a professional veterinary medical (PVM) program. The following questions guided the study: (1) How does the use of technology affect faculty teaching behaviors? (2) Do the facilitators' interactions with WebCT technology change over the course of one semester? (3) What is the perceived impact of WebCT on facilitators' role in PBL? The study employed a combination of qualitative (case study) and semi-quantitative (survey) methods to explore these issues. Nine clinical sciences faculty members, leading a total of six PBL groups, were observed over the course of an academic semester for a total of 20 instructional sessions. The qualitative data gathered by observing faculty as they facilitated PBL sessions yielded three major themes: (1) How do PBL facilitators adapt to the addition of WebCT technology? (2) Does this technology affect teaching? and (3) How do PBL facilitators interact with their students and each other over the course of a semester? No direct evidence was found to suggest that use of WebCT affected teaching behaviors (e.g., student-centered vs. teacher-centered instruction). However, all facilitators showed a moderate increase in comfort with the technology during the semester, and one participant showed remarkable gains in technology skills. The teaching theme provided insight into how facilitators foster learning in a PBL setting as compared to a traditional lecture. A high degree of variability in teaching styles was observed, but individuals' styles tended to remain stable over the course of the semester. Nevertheless, all facilitators interacted similarly with students, in a more caring and approachable manner, when compared to the classroom or clinic atmospheres.

A retrospective evaluation of transthoracic biphasic electrical cardioversion for atrial fibrillation in dogs.

OBJECTIVES: To evaluate safety, efficacy, and clinical usefulness of biphasic transthoracic cardioversion for management of dogs with atrial fibrillation (AF). BACKGROUND: In dogs AF is usually managed with heart rate control rather than by restoration of sinus rhythm (SR). However, restoration of SR has potential advantages of improving cardiac output and reducing ventricular filling pressures, and biphasic cardioversion provides an improved benefit/risk ratio compared to traditional monophasic cardioversion. ANIMALS, MATERIALS AND METHODS: Retrospective analysis of data from 39 dogs with spontaneous AF managed with biphasic transthoracic cardioversion was done. Conversion characteristics, adverse effects, and duration of SR were evaluated. Effects of heart disease and pretreatment with amiodarone on success of cardioversion and on duration of SR were also evaluated. RESULTS: Restoration of SR was achieved in 36 of 39 dogs (92.3%). Presence of heart disease or atrial enlargement had no effect on cardioversion characteristics or ability to restore SR. Median duration of SR following cardioversion and treatment with amiodarone was 120 days. Dogs with lone AF remained in SR longer than those with heart disease. CONCLUSIONS: Biphasic cardioversion is safe and effective. Although duration of SR varied, a majority of dogs remained in SR long enough to benefit.

Secure pacemaker fixation critical for prevention of Twiddler's syndrome.

A two year old, female spayed border collie presented three weeks after permanent pacemaker implantation for weakness, lethargy and collapse. Electrocardiogram documented complete (3(rd) degree) atrioventricular (AV) block, the absence of pacing and a ventricular escape rhythm. Thoracic radiographs revealed retraction and dislodgement of the passive fixation lead from the right ventricular apex. During a procedure to reposition the lead, it was noted that lead retraction had resulted from rotation of the generator with twisting and entanglement of the lead on itself and around the generator, a complication recognized in human patients as "Twiddlers syndrome". The pacemaker lead was removed, a new lead securely placed at the right ventricular apex, and the generator was secured into a revised subcutaneous pocket. Pacing was re-established and the Twiddler's syndrome has not reoccurred.