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A six-year-old Brussels griffon was presented for cervical swelling three months after implantation of a transvenous pacemaker. Transthoracic echocardiography demonstrated a thrombus associated with the pacemaker lead, partially obstructing right atrial inflow. The laboratory findings were consistent with protein-losing nephropathy. Initial medical therapy consisted of rivaroxaban (0.68 mg/kg orally every 24 hours), clopidogrel (2.5 mg/kg orally every 24 hours), and enalapril (0.5 mg/kg orally every 12 hours). Resolution of cervical and thoracic edema was noted within two weeks of initiating therapy. Recheck echocardiography two months and one year later revealed decreasing thrombus size despite worsening proteinuria. To the authors' knowledge, this is the first documented use of rivaroxaban for successful medical treatment of cranial vena cava syndrome caused by intracardiac pacemaker lead thrombosis in a hypercoagulable patient.

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BACKGROUND: A 5-year-old, healthy English Springer Spaniel died suddenly 4 months after delivering a litter of 7 puppies. Within 4 months of the dam's death, 3 offspring also died suddenly. HYPOTHESIS: Abnormal cardiac repolarization, caused by an inherited long QT syndrome, is thought to be responsible for arrhythmias leading to sudden death in this family. ANIMALS: Four remaining dogs from the affected litter and 11 related dogs. METHODS: Physical examination and resting ECG were done on the littermates and 9 related dogs. Additional tests on some or all littermates included echocardiogram with Doppler, Holter monitoring, and routine serum biochemistry. Blood for DNA sequencing was obtained from all 15 dogs. RESULTS: Three of 4 littermates examined, but no other dogs, had prolonged QT intervals with unique T-wave morphology. DNA sequencing of the KCNQ1 gene identified a heterozygous single base pair mutation, unique to these 3 dogs, which changes a conserved amino acid from threonine to lysine and is predicted to change protein structure. CONCLUSIONS AND CLINICAL IMPORTANCE: This family represents the first documentation in dogs of spontaneous familial QT prolongation, which was associated with a KCNQ1 gene mutation and sudden death. Although the final rhythm could not be documented in these dogs, their phenotypic manifestations of QT interval prolongation and abnormal ECG restitution suggested increased risk for sudden arrhythmic death. The KCNQ1 gene mutation identified is speculated to impair the cardiac repolarizing current IKs, similar to KCNQ1 mutations causing long QT syndrome 1 in humans.

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Ractopamine, a synthetic ß(2)-adrenoceptor agonist, is widely used as a feed additive in the United States to promote a reduction in body fat and enhance muscle growth in cattle, pigs, and turkeys. It has the potential for illegal use in show and racing animals because it may affect performance via its ß-adrenergic agonist properties or anabolic activities. Nine greyhounds were orally administered 1 mg/kg of ractopamine to investigate the ability to detect the drug in urine. Postdosing, 7 of 9 dogs developed cardiac arrhythmias and had elevated troponin levels indicating myocardial damage. One dog necropsied 4 days postdosing had massive myocardial necrosis, mild to focally moderate skeletal muscle necrosis, and widespread segmental arterial mediolysis. A second dog necropsied 17 days postdosing had mild myocardial necrosis and fibrosis. Scattered arteries exhibited segmental medial and perimedial fibromuscular dysplasia. This is the first reported case of arterial, cardiac, and skeletal muscle damage associated with ractopamine.

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Patients undergoing extracorporeal membrane oxygenation (ECMO) are at increased risk of infection. We present the first known report of nosocomial infection with Cupriavidus pauculus attributable to contamination from ECMO equipment and describe the measures taken to halt subsequent infections. A cluster of infections in ECMO patients should prompt team members to consider contamination of equipment with environmental pathogens as a possible cause.

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Twenty dogs with patent ductus arteriosus occluded with Hemoclips were evaluated with a mean follow-up time of 799.4 days (range, 83 to 3,580 days). Significant decreases were found between pre- and postsurgical means for vertebral heart size and for echocardiographic left atrial/aortic-root ratios and percent fractional shortening (%FS). Despite a good clinical outcome, six of 20 dogs had persistent cardiomyopathy of overload with diminished %FS (28% or less) at follow-up. One dog had residual ductal flow identified five days postoperatively. Subsequent evaluations in this case at 60, 144, 226, 344, and 560 days postoperatively demonstrated gradually diminishing ductal flow. The remaining 19 dogs did not recanalize.

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BACKGROUND: Although African Americans are disproportionately affected by the AIDS epidemic, they are underrepresented in AIDS research, particularly in AIDS clinical trials. This study examines a multidimensional construct of distrust and other factors that may affect willingness to participate in AIDS research. METHODS: A total of 301 African Americans (aged >/=18 years) in Durham, North Carolina participated in a cross-sectional survey. In-person interviews, 20 to 25 minutes in length, were conducted with participants. Structural equation modeling was used to develop models exploring distrust and other factors affecting willingness to participate in AIDS research among African Americans. RESULTS: Distrust was the strongest inverse predictor of willingness to participate in AIDS clinical trials. Distrust was not significantly associated with willingness to participate in AIDS surveys and educational interventions. Altruism, facilitators/barriers, religiosity, and economic group membership were also significantly associated with willingness to participate in AIDS clinical trials. Only altruism was significantly associated with willingness to participate in AIDS surveys and educational interventions. CONCLUSIONS: Distrust about research institutions is a significant barrier to recruiting African Americans in AIDS clinical trials. Issues of distrust need to be acknowledged by researchers to develop better recruitment and retention strategies when conducting AIDS clinical trials in African-American communities.

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OBJECTIVE: To develop a clinically useful model for predicting QT interval duration as a function of heart rate in healthy cats. ANIMALS: 20 healthy cats. PROCEDURE: For all cats, results of a physical examination, electrocardiography, and echocardiography were normal. Twenty-four hour heart rate and rhythm data were collected by means of ambulatory electrocardiography. Hourly ECG segments were obtained from the 24-hour recordings. Mean heart rate and the mean of 5 QT interval measurements were calculated for each of 479 usable ECG segments. Analysis of covariance was used to develop models to describe variability in QT interval duration. RESULTS: Prediction equations (R2 = 0.81) including terms for heart rate, (heart rate)2, age group (1 to 4 vs 8 to 14 years old), and their interactions were developed. Sex, individual cat, and time of day were of little value in predicting QT interval duration. A simplified prediction equation without age group (R2 = 0.71) also was developed and had better predictive ability than reported correction formulas for QT interval duration. CONCLUSIONS AND CLINICAL RELEVANCE: Prediction equations with 95% prediction intervals for expected QT interval duration in healthy cats were generated. Abnormal QT interval duration can be associated with cardiac electrical instability, yet QT interval duration is greatly influenced by heart rate. Results of the present study provide reference ranges for expected QT interval duration as a function of heart rate in healthy cats.

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Twenty-four-hour ambulatory electrocardiograms were recorded in two age groups of 10 normal cats each: group 1 (1 to 4 years) and group 2 (8 to 14 years), with equal numbers of males and females in each group. Average heart rates over the 24-hour recording period ranged from 114 to 202 beats/minute (bpm). The mean 24-hour average rate did not differ between group 1 and group 2 (157.6 vs. 156.3+/-5.3 bpm, respectively); however, females (both groups combined) had higher average heart rates than males (166.8 vs. 147.1+/-5.3 bpm, respectively). Females also had a higher mean minimum heart rate than males (116.9 vs. 96.5+/-4.2 bpm, respectively); but there were no gender or age group differences in maximum heart rate. Results of hourly analyses of average, minimum, and maximum heart rates were similar. Mean heart rates rose from mid-afternoon to about 9:00 PM and were lowest just after midnight. Although regular sinus rhythm predominated, periods of sinus arrhythmia were evident in most cats, especially in early morning hours. Supraventricular extrasystoles were uncommon. Isolated ventricular extrasystoles occurred more frequently in group 2 cats; multiform configuration was observed in both groups. Repetitive ventricular extrasystoles, which usually consisted of occasional couplets, occurred more frequently in group 2 cats. One older cat had 2 short runs of ventricular tachycardia. Another older cat appeared to have a recurrent accelerated idioventricular rhythm.

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A Veterinary Medical Database search from 1982 to 1995 identified 1,383 dogs with tumors of the heart from a total population of 729,265 dogs (0.19% incidence). Hemangiosarcoma (HSA) was the most common cardiac tumor identified. In the subset of dogs with specific histologic diagnoses, the number with HSA was almost 10-fold that of the 2nd most common tumor, aortic body tumor. Primary heart tumors were more common than cardiac metastases. When biologic behavior was noted, most heart tumors were classified as malignant. Cardiac tumors (excluding lymphoma) occurred most often in dogs between the ages of 7 and 15 years. In very old dogs (>15 years), the frequency of cardiac tumors was the same or lower than that of the youngest age group. Tumors occurred with similar frequency in males and females, but the relative risk for spayed females was >4 times that for intact females. For HSA, spayed females had >5 times greater relative risk than did intact females. The risk for castrated males was slightly greater than that for intact males, which had 2.4 times the relative risk of intact females. Thus, neutering appeared to increase the risk of cardiac tumor in both sexes. Intact females were least likely to develop a cardiac tumor, whereas spayed females were most likely to develop a tumor. Twelve breeds had greater than average risk of developing a cardiac tumor, whereas 17 had lower risk.

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OBJECTIVES: To determine the pharmacokinetics of atenolol (AT) after i.v. and oral administrations in cats, to assess duration of beta-blocking effect, and to determine whether AT can be effectively used once per day. ANIMALS: 9 clinically normal cats. PROCEDURE: Single doses of 1 (i.v.) or 3 (oral) mg of AT/kg of body weight were administered to each cat on different occasions, and serial blood samples were collected. Plasma concentrations of AT were subsequently determined, using high-performance liquid chromatography. The plasma concentration data were analyzed, using noncompartmental analysis. An isoproterenol challenge test was used to determine the beta-blocking effect of AT on heart rate after 3 consecutive days of oral treatment (3 mg/kg, once a day). RESULTS: After i.v. administration, mean +/- SD apparent volume of distribution at steady state and systemic clearance values were 1,088 +/- 148 ml/kg and 259 +/- 72 ml/h/kg, respectively. Bioavailability was 90 +/- 9% after oral administration. The half-life values were 3.44 +/- 0.5 and 3.66 +/- 0.39 hours after i.v. and oral administrations, respectively. Compared with baseline values prior to AT administration, heart rates at 6 and 12 hours after administration of AT were significantly reduced. CONCLUSIONS: AT has high oral bioavailability in cats, resulting in small interindividual variability in its kinetics in this species. The drug has beta-blocking effect in cats, as indicated by the attenuated heart rate response to isoproterenol; this effect persists for at least 12 hours in clinically normal cats.

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PURPOSE: This prospective longitudinal study examined the relationship between interpersonal support and patient satisfaction with orthognathic surgery. PATIENTS AND METHODS: Fifty-five adult patients were assessed with two questionnaires measuring the level of general social support they perceived receiving from significant others during treatment, and the level of perceived support specifically for their decision to undergo orthognathic surgery and the treatment results. RESULTS: Availability of support and satisfaction with support from specific members of the patient's support group were found to be related to satisfaction in the early postoperative period. Support of close friends for the patient's decision to undergo surgery was found to be associated with satisfaction in the early postoperative months. Further, reactions of the patient's support group to his or her postoperative appearance was found to be highly related to satisfaction in both the early and late postoperative stages.

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Randomization tests have been proposed as a statistical method for analyzing the data from single-case designs. A case is made for incorporating a responsive element into randomized designs. A partially responsive, partially randomized single-case design is presented, and an example is given to illustrate the design and the corresponding randomization test.

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Mitral stenosis was diagnosed in 15 young to middle-aged dogs. There were 5 Newfoundlands and 4 bull terriers affected, suggesting a breed predisposition for this disorder. Clinical signs included cough, dyspnea, exercise intolerance, and syncope. Soft left apical diastolic murmurs were heard only in 4 dogs, whereas 8 dogs had systolic murmurs characteristic of mitral regurgitation. Left atrial enlargement was the most prominent radiographic feature. Left-sided congestive heart failure was detected by radiographs in 11 dogs within 1 year of diagnosis. Electrocardiographic abnormalities varied among dogs and included atrial and ventricular enlargement, as well as atrial and ventricular arrhythmias. Abnormalities on M-mode and two-dimensional echocardiograms included abnormal diastolic motion of the mitral valve characterized by decreased leaflet separation, valve doming, concordant motion of the parietal mitral valve leaflet, and a decreased E-to-F slope. Increased mitral valve inflow velocities and prolonged pressure half-times were detected by Doppler echocardiography. Cardiac catheterization, performed in 8 dogs, documented a diastolic pressure gradient between the left atrial, pulmonary capillary wedge, or pulmonary artery diastolic pressures and the left ventricular diastolic pressure. Necropsy showed mitral stenosis caused by thickened, fused mitral valve leaflets in 5 dogs and a supramitral ring in another dog. The outcome in affected dogs was poor; 9 of 15 dogs were euthanatized or died by 2 1/2 years of age.

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Addition of the polyene antibiotic amphotericin B or tissue culture medium to nondifferentiated HL-60 cells in the presence of luminol induces a chemiluminescence signal that reaches a peak value within a few seconds and decays exponentially in less than a minute. The kinetics of the signal and its modulation by superoxide dismutase, catalase, and horseradish peroxidase are consistent with a series of solution biochemical processes with a rate-determining step corresponding to the disproportionation of a luminol-superoxide complex. The effects of the enzymes demonstrate that superoxide is a precursor to the rate-determining intermediate and that both catalase and peroxide enhance a reaction that competes with the rate-limiting process.

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Fourier transform infrared (IR) spectroscopic studies of phosphatidylserine/cholesterol/Ca2+ complexes are reported using the synthetic phosphatidylserines (PS) 1,2-dioleoyl-sn-glycero-3-phospho-L-serine (DOPS), 1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS), and 1,2-dimyristoyl-sn-glycero-3-phospho-L-serine (DMPS). IR spectra reveal that cholesterol does not significantly alter the binding nature of Ca2+ to PS molecules; Ca2+ binds to the phosphate ester group of PS in the presence of cholesterol up to 50 mol% as in the case of pure PS bilayers. However, the IR data indicate that the presence of cholesterol induces disorder of the acyl chain packing, increases the degree of immobilization of the interfacial and polar regions, and increases the degree of dehydration of the PS/Ca2+ complexes.

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The effects of IV administered amiodarone, a class-III antiarrhythmic agent, on myocardial contractility, early myocardial relaxation, and hemodynamic variables were evaluated in normal canine hearts and those with infarcts. In the normal canine heart, amiodarone had important, but relatively mild, depressant effects on left ventricular contractility (assessed by maximal positive first derivative of left ventricular pressure (+dP/dtmax) and maximal elastance (Emax)) and heart rate when given IV at a dose of 10 mg/kg of body weight. An effect on contractility or active relaxation (assessed by maximal negative first derivative of left ventricular pressure (-dP/dtmax) and the time constant of isovolumic pressure decrease) was not identified with smaller doses. Myocardial infarction itself caused a predictable and marked depressant effect on myocardial contractility, as indicated by decreases in +dP/dtmax, ejection fraction, Emax, and -dP/dtmax, and elevation in end diastolic pressure. Additional depressive effects on contractility and active relaxation resulted when 10 mg of amiodarone/kg was administered to dogs with myocardial infarction and these effects were sufficient to worsen acute myocardial infarction-induced heart failure. Significant changes attributable to heart rate alone could not be identified. On the basis of our findings, we suggest that amiodarone administered IV should be used with caution in dogs with compromised ventricular function.

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