Objective—To determine whether Boxers with a clinical
diagnosis of arrhythmogenic right ventricular cardiomyopathy
(ARVC) have increased plasma concentrations
of brain natriuretic peptide (BNP), compared
with concentrations in clinically normal dogs.
Animals—13 Boxers with ARVC, 9 clinically normal
Boxers, 10 clinically normal non-Boxer dogs, and 5
hound dogs with systolic dysfunction.
Procedure—All Boxers were evaluated via 24-hour
ambulatory electrocardiography and echocardiography;
the number of ventricular premature contractions
(VPCs) per 24 hours was assessed. Hound
dogs with cardiac pacing-induced systolic dysfunction
(positive control dogs) and clinically normal non-Boxer
dogs (negative control dogs) were evaluated
echocardiographically. Three milliliters of blood was
collected from each dog for measurement of plasma
BNP concentration by use of a radioimmunoassay.
Results—Mean ± SD plasma BNP concentration for
the ARVC-affected Boxers, clinically normal Boxers,
negative control dogs, and positive control dogs was
11.0 ± 4.6 pg/mL, 7.9 ± 3.2 pg/mL, 11.5 ± 4.9 pg/mL,
and 100.8 ± 56.8 pg/mL, respectively. Compared with
findings in the positive control group, plasma BNP
concentration in each of the other 3 groups was significantly
different. There was no significant difference
in BNP concentration between the 2 groups of
Boxers. A significant correlation between plasma BNP
concentration and number of VPCs per 24 hours in
the ARVC-affected Boxers was not identified.
Conclusions and Clinical Relevance—A significant
difference in BNP concentration between Boxers with
ARVC and clinically normal Boxers was not identified.
Results suggest that BNP concentration may not be
an indicator of ARVC in Boxers. (Am J Vet Res
Objective—To use an index of myocardial performance (IMP) to assess right ventricular function in Boxers with arrhythmogenic right ventricular cardiomyopathy (ARVC).
Animals—22 Boxers (12 Boxers with ARVC diagnosed by the detection of ≥ 1,000 ventricular premature complexes (VPCs)/24 h and 10 Boxers with ≤ 5 VPCs/24 h (control dogs).
Procedures—Pulsed-wave Doppler recordings of tricuspid inflow and pulmonic outflow were acquired. Preejection period (PEP), ejection time (ET), PEP/ET, and IMP were determined for the right ventricle by use of data from separate cardiac cycles.
Results—A significant difference was not identified between groups for right ventricular PEP, right ventricular ET, right ventricular PEP/ET, or right ventricular IMP. Right ventricular IMP was not significantly correlated with VPC number (r = 0.21) or VPC grade (r = −0.3) in Boxers with ARVC.
Conclusions and Clinical Relevance—Boxers with ARVC did not have significant differences in right ventricular IMP, compared with results for control Boxers. This would suggest that right ventricular dysfunction does not develop in Boxers with ARVC or that a more severe phenotype of the disease may be necessary for detection of dysfunction. Additional studies that use more sensitive techniques to evaluate myocardial function may be warranted.
Objective—To evaluate serum cardiac troponin I (cTnI) concentrations in Boxers with arrhythmogenic right ventricular cardiomyopathy (ARVC), unaffected (control) Boxers, and control non-Boxers.
Animals—10 Boxers with a clinical diagnosis of ARVC defined by ≥ 1,000 ventricular premature complexes (VPCs)/24 h on an ambulatory ECG, 10 control Boxers assessed as normal by the presence of < 5 VPCs/24h, and 10 control non-Boxers.
Procedures—Serum was extracted from a blood sample from each dog. Analysis of serum cTnI concentrations was performed.
Results—Mean ± SD serum cTnI concentration was 0.142 ± 0.05 ng/mL for Boxers with ARVC, 0.079 ± 0.03 ng/mL for control Boxers, and 0.023 ± 0.01 ng/mL for control non-Boxers. A significant difference in serum cTnI concentrations was observed among the 3 groups. In the combined Boxer population (ie, Boxers with ARVC and control Boxers), a significant correlation was found between serum cTnI concentration and number of VPCs/24 h (r = 0.78) and between serum cTnI concentration and grade of ventricular arrhythmia (r = 0.77).
Conclusions and Clinical Relevance—Compared with clinically normal dogs, Boxers with ARVC had a significant increase in serum cTnI concentration. For Boxers, correlations were found between serum cTnI concentration and number of VPCs/24 h and between concentration and the grade of arrhythmia. Because of the overlap in serum cTnI concentrations in control Boxers and Boxers with ARVC, future studies should evaluate the correlation of serum cTnI concentration with severity of disease in terms of degree of myocardial fibrofatty changes.
CASE DESCRIPTION A 6-month-old sexually intact male domestic shorthair cat was referred for evaluation of a heart murmur and ventricular septal defect (VSD).
CLINICAL FINDINGS Physical examination revealed a grade 5/6 right apical systolic heart murmur. Findings on thoracic radiography were consistent with moderate right and left ventricular enlargement, left atrial enlargement, and enlargement of the pulmonary arteries and veins; an interstitial pulmonary pattern was also evident. Echocardiography revealed a perimembranous VSD with left-to-right shunting combined with trace mitral valve regurgitation. The cat later developed a dry cough, the intensity of the heart murmur increased to grade 6/6, and signs of left-sided congestive heart failure developed.
TREATMENT AND OUTCOME Medical treatment included enalapril maleate and furosemide. When the cat's condition worsened despite medical treatment, palliative pulmonary artery banding was performed. During surgery, blood pressure in the pulmonary artery was measured with a pulmonary artery catheter, and pulmonary artery banding was successfully achieved with a polytetrafluoroethylene band and hemoclips. The pulmonary-to-systemic blood flow ratio was reduced from 3 to 1.5, and signs of congestive heart failure resolved within 2 weeks after surgery.
CLINICAL RELEVANCE Findings suggested that cats with a VSD and pulmonary-to-systemic flow ratio > 3 or with congestive heart failure attributable to a VSD could be considered candidates for palliative pulmonary artery banding to alleviate clinical signs. However, further investigation into long-term prognosis with objective outcome measurements and with multiple cases is needed. (J Am Vet Med Assoc 2019;254:723–727)
Objective—To determine the prevalence of ventricular arrhythmias in clinically normal adult Boxers.
Design—Prospective cross-sectional study.
Animals—301 Boxers (181 females and 120 males) > 1 year old with echocardiographically normal systolic function and no history of syncope or congestive heart failure.
Procedures—Physical examination, which included echocardiography, was performed on all dogs. A 24-hour ambulatory ECG was performed on each dog, and results were evaluated to assess ventricular arrhythmias. Statistical evaluation was performed to determine correlations between the total number of ventricular premature complexes (VPCs)/24 h, grade of ventricular arrhythmia, and age of the dogs.
Results—Age of dogs ranged from 1 to 16 years (median, 4 years). Number of VPCs/24 h in each dog ranged from 0 to 62,622 (median, 6 VPCs/24 h). Grade of arrhythmias ranged from 0 to 3 (median, 1). Age was correlated significantly with number of VPCs/24 h (r = 0.43) and with grade of arrhythmia (r = 0.37). Number of VPCs/24 h was significantly correlated with grade of arrhythmia (r = 0.82).
Conclusions and Clinical Relevance—Clinically normal adult Boxers generally had < 91 VPCs/24 h and an arrhythmia grade < 2. Boxers with > 91 VPCs/24 h were uncommon and may have represented dogs with arrhythmogenic right ventricular cardiomyopathy or other disease processes that could have resulted in the development of ventricular arrhythmias.
Objective—To identify clinical, echocardiographic,
and electrocardiographic abnormalities in Boxers with
cardiomyopathy and echocardiographic evidence of
left ventricular systolic dysfunction.
Animals—48 mature Boxers.
Procedure—Medical records were reviewed for information
on age; sex; physical examination findings;
and results of electrocardiography, 24-hour ambulatory
electrocardiography, thoracic radiography, and
Results—Mean age of the dogs was 6 years (range, 1
to 11 years). Twenty (42%) dogs had a systolic murmur,
and 9 (19%) had ascites. Congestive heart failure was
diagnosed in 24 (50%) dogs. Seventeen (35%) dogs
had a history of syncope. Mean fractional shortening
was 14.4% (range, 1% to 23%). Mean left ventricular
systolic and diastolic diameters were 4.5 cm (range, 3
to 6.3 cm) and 5.3 cm (range, 3.9 to 7.4 cm), respectively.
Twenty-eight (58%) dogs had a sinus rhythm
with ventricular premature complexes (VPCs), and 20
had supraventricular arrhythmias (15 with atrial fibrillation
and 5 with sinus rhythm and atrial premature complexes).
Sixteen of the dogs with supraventricular
arrhythmias also had occasional VPCs. Morphology of
the VPCs seen on lead II ECGs was consistent with left
bundle branch block in 25 dogs, right bundle branch
block in 8, and both in 11.
Conclusions and Clinical Relevance—Results suggest
that Boxers with cardiomyopathy and left ventricular
dysfunction frequently have arrhythmias of supraventricular
or ventricular origin. Whether ventricular dysfunction
was preceded by electrical disturbances could
not be determined from these data, and the natural history
of myocardial disease in Boxers requires further
study. (J Am Vet Med Assoc 2005;226:1102–1104)