A 2-year-old 24-kg (53-lb) spayed female American Staffordshire Terrier was referred to the Texas A&M Veterinary Medical Teaching Hospital for potential pacemaker placement. Six days prior, the dog began to vomit persistently and became lethargic, anorectic, and hypodipsic. Results of a CBC (performed at the referring veterinary clinic) were within reference ranges. An abbreviated serum biochemical profile performed at the referring clinic revealed high BUN (66.4 mg/dL; reference range, 9.0 to 29.0 mg/dL) and creatinine (1.8 mg/dL; reference range, 0.4 to 1.4 mg/dL) concentrations; serum electrolyte concentrations were not measured. The referring veterinarian had administered a dose of barium contrast
Objective—To determine the pharmacokinetics of
carvedilol administered IV and orally and determine
the dose of carvedilol required to maintain plasma
concentrations associated with anticipated therapeutic
efficacy when administered orally to dogs.
Animals—8 healthy dogs.
Procedures—Blood samples were collected for 24
hours after single doses of carvedilol were administered
IV (175 µg/kg) or PO (1.5 mg/kg) by use of a
crossover nonrandomized design. Carvedilol concentrations
were detected in plasma by use of high-performance
liquid chromatography. Plasma drug concentration
versus time curves were subjected to noncompartmental
Results—The median peak concentration (extrapolated)
of carvedilol after IV administration was
476 ng/mL (range, 203 to 1,920 ng/mL), elimination
half-life (t1/2) was 282 minutes (range, 19 to 1,021
minutes), and mean residence time (MRT) was 360
minutes (range, 19 to 819 minutes). Volume of distribution
at steady state was 2.0 L/kg (range, 0.7 to 4.3
L/kg). After oral administration of carvedilol, the median
peak concentration was 24 µg/mL (range, 9 to
173 µg/mL), time to maximum concentration was 90
minutes (range, 60 to 180 minutes), t1/2 was 82 minutes
(range, 64 to 138 minutes), and MRT was 182
minutes (range, 112 to 254 minutes). Median bioavailability
after oral administration of carvedilol was 2.1%
(range, 0.4% to 54%).
Conclusions and Clinical Relevance—Although
results suggested a 3-hour dosing interval on the
basis of MRT, pharmacodynamic studies investigating
the duration of β-adrenoreceptor blockade provide a
more accurate basis for determining the dosing interval
of carvedilol. (Am J Vet Res 2005;66:2172–2176)
Case Description—A 12-year-old Miniature Dachshund with a history of permanent endocardial pacemaker implantation performed 7 weeks previously was admitted for routine dental prophylaxis.
Clinical Findings—Preanesthetic ECG revealed normal ventricular capture. Thoracic radiographic findings included caudomedial displacement of the endocardial pacemaker lead. Echocardiography revealed moderate chronic degenerative valve disease with moderate left atrial and ventricular dilation. After induction of anesthesia, loss of ventricular capture was detected. The dog recovered from anesthesia and had improved ventricular capture. The following day, surgical exposure of the cardiac apex revealed perforation of the right ventricular apex by the passive-fixation pacemaker lead.
Treatment and Outcome—A permanent epicardial pacemaker was implanted through a transxiphoid approach. Appropriate ventricular capture and sensing were achieved. The dog recovered without complications. Approximately 2 months later, the dog developed sudden respiratory distress at home and was euthanized.
Clinical Relevance—In dogs with permanent pacemakers and loss of ventricular capture, differential diagnoses should include cardiac perforation. If evidence of perforation of the pacemaker lead is found, replacement of the endocardial pacemaker lead with an epicardial pacemaker lead is warranted.
Case Description—A 3-year-old sexually intact male Standard Poodle was admitted to the veterinary teaching hospital for transcatheter closure of a large atrial septal defect (ASD).
Clinical Findings—The dog had exercise intolerance and was thin. Findings on physical examination were within normal limits with the exception of a left base systolic heart murmur (grade 5/6). The dog was not receiving any medications. Echocardiography and thoracic radiography confirmed the diagnosis of ASD and revealed compensatory changes consistent with a large left to right shunting ASD. Results of serum biochemical analysis and CBC were within reference range limits.
Treatment and Outcome—Transcatheter ASD closure with an atrial septal occluder (ASO) was performed and failed. An open heart surgical approach under cardiopulmonary bypass was declined by the dog's owners. The dog underwent a novel hybrid approach involving active device fixation under temporary inflow occlusion after transatrial device deployment. The dog recovered with some manageable postoperative complications. As of the last follow-up examination, the dog had 10 months of event-free survival.
Clinical Relevance—Transcatheter closure by use of an ASO and open heart patch repair with cardiopulmonary bypass to surgically treat dogs with ASD has been reported. Transcatheter closure is not possible in dogs with large ASD. The novel hybrid procedure reported herein represented a viable alternative to euthanasia.
Objective—To report the outcome of minimally invasive surgical treatment of heartworm caval syndrome in a series of dogs and to provide information on long-term survival of patients with this condition.
Design—Retrospective case series.
Animals—42 client-owned dogs with a diagnosis of heartworm caval syndrome.
Procedures—Information on history, clinical, laboratory, and diagnostic imaging findings and treatment was obtained from medical records. When possible, additional follow-up information was obtained through telephone interviews with referring veterinarians and owners.
Results—Of the 42 dogs with caval syndrome, 21 underwent minimally invasive surgical treatment consisting of transvenous heartworm extraction. Two of the 21 dogs died during the procedure, and after surgery, 4 died. Following induction of anesthesia, heartworms migrated into the distal portion of the pulmonary artery in 1 dog; therefore, extraction was not attempted. Transvenous heartworm extraction was completed successfully in 14 dogs, and all 14 of these dogs were discharged from the hospital. Mean follow-up time in these 14 dogs was 24.4 ± 17.7 months with a range of 2 to 56 months. At the time of final follow-up, 10 of these 14 dogs had survived at least 18 months and 7 had survived > 24 months. By the end of the study, 1 dog was lost to follow-up and 3 had been euthanatized for unrelated reasons.
Conclusions and Clinical Relevance—Results of the study reported here suggest that dogs with caval syndrome that undergo successful transvenous heartworm extraction and survive to discharge have a good long-term prognosis.
Case Description—2 cats were examined because of congestive heart failure secondary to heartworm infection.
Clinical Findings—One cat had severe abdominal distention and the other had dyspnea secondary to chylothorax. Both had loud right-sided heart murmurs, precordial thrills, and jugular distension. Thoracic radiography revealed cardiomegaly and enlarged caudal pulmonary arteries. Echocardiography revealed tricuspid regurgitation and multiple hyperechoic structures consistent with adult Dirofilaria immitis within the right atrium, right ventricle, and main pulmonary artery. Pulmonary hypertension was documented by means of Doppler echocardiography in 1 cat.
Treatment and Outcome—Cats were anesthetized, and a nitinol gooseneck snare catheter was introduced into the right side of the heart via a jugular venotomy. In the first cat, the snare was used to retrieve 5 female and 2 male adult D immitis. The catheter was then passed into the main pulmonary artery in an unsuccessful attempt to retrieve remaining heartworms. In the second cat, 2 adult female D immitis were removed from the right atrium with the nitinol snare. In both cats, clinical signs resolved within 4 weeks after the procedure.
Clinical Relevance—Findings suggested that use of a nitinol gooseneck snare catheter may be a safe and effective technique for removing adult D immitis from the right atrium and ventricle in cats and that successful removal of adult heartworms in infected cats may resolve clinical signs of right-sided congestive heart failure and chylothorax. In addition, findings in 1 cat suggested that removal of all adult heartworms may not be necessary for clinical signs to resolve.
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.
The science and clinical usefulness of cardiac biomarker measurement in veterinary patients is a subject of increasing interest. Despite progress in our understanding of the potential clinical applications of NT-proBNP measurement, clear recommendations for use of the NT-proBNP assay are lacking, and for many clinical scenarios, use of this assay requires further study. The purpose of this report is to render the collective opinion of a group of investigators who have been involved in NT-proBNP studies in veterinary patients or in formulating recommendations for use of an NT-proBNP assay in human medicine (FZ).1 Our objective was to interpret
Objective—To evaluate the effect of 4 antiarrhythmic
treatment protocols on number of ventricular premature
complexes (VPC), severity of arrhythmia, heart
rate (HR), and number of syncopal episodes in Boxers
with ventricular tachyarrhythmias.
Design—Randomized controlled clinical trial.
Procedure—Dogs with > 500 VPC/24 h via 24-hour
ambulatory ECG (AECG) were treated with atenolol
(n = 11), procainamide (11), sotalol (16), or mexiletine
and atenolol (11) for 21 to 28 days. Results of pre- and
posttreatment AECG were compared with regard to
number of VPC/24 h; maximum, mean, and minimum
HR; severity of arrhythmia; and occurrence of syncope.
Results—Significant differences between pre- and
posttreatment number of VPC, severity of arrhythmia,
HR variables, or occurrence of syncope were not
observed in dogs treated with atenolol or procainamide.
Significant reductions in number of VPC,
severity of arrythmia, and maximum and mean HR
were observed in dogs treated with mexiletineatenolol
or sotalol; occurrence of syncope was not significantly
different between these 2 treatment groups.
Conclusions and Clinical Relevance—Treatment
with sotalol or mexiletine-atenolol was well tolerated
and efficacious. Treatment with procainamide or
atenolol was not effective. (J Am Vet Med Assoc 2002;221:522–527)