Objective—To determine whether logarithmic and
polynomial models are superior to simple linear models
for predicting reference values for M-mode echocardiographic variables in dogs with a wide range
of body weights.
Animals—69 apparently healthy adult male and
female dogs of various breeds, ages (range, 1 to 12
years; median, 3.5 years), and body weights (range,
3.9 to 97.7 kg; median, 25.4 kg).
Procedure—Echocardiographic M-mode measurements
of the interventricular septum, left ventricular
dimension (LVD), left ventricular wall, aorta, and left
atrium were obtained. Simple linear, second-order
polynomial, third-order polynomial, and logarithmic
regression models were determined by use of the
least-squares method to describe the relationship
between M-mode measurements and body weight.
Differences in adjusted R2 values of logarithmic and
polynomial models were tested for significance of
contribution, compared with the simple linear
Results—Significant differences in adjusted R2 were
found when comparing simple linear with logarithmic
or polynomial models for LVD-diastole, LVD-systole,
aorta, and left atrium. Differences in adjusted R2
between second-order polynomial, third-order polynomial,
and logarithmic models were not significant for
any M-mode measurement.
Conclusions and Clinical Relevance—In this study,
logarithmic or second-order polynomial models predicted
reference values of M-mode measurements
for size of the cardiac chambers better than simple linear
models for dogs with a wide range of body
weights. Logarithmic and polynomial models were
not superior to simple linear models for M-mode measurements
of cardiac wall thickness. (Am J Vet Res
Objective—To describe surgical techniques for and
assess outcome of treatment of mitral regurgitation
Design—Uncontrolled prospective study.
Animals—18 dogs with naturally occurring mitral
Procedure—All dogs weighed > 5 kg (11 lb) and had
severe mitral regurgitation, congestive heart failure
(CHF), and no serious noncardiac disease. Left ventricular
volume indices, left atrial size, and degree of
mitral regurgitation were determined echocardiographically
before and after surgery. Repair techniques
included circumferential annuloplasty, placement
of artificial chordae, chordal fenestration and
papillary muscle splitting, and edge-to-edge repair.
Factors predictive for surgery survival and resolution
of CHF were determined.
Results—12 dogs survived surgery. Factors predictive
for surgery survival included weight > 10 kg (22 lb) and
CHF of less than 6 months' duration. In 9 dogs, CHF
resolved for a median period of 1 year (range, 4
months to 3 years) after surgery. One dog had stable
CHF at 12 months. One dog died as a result of progressive
CHF; another was euthanatized for a noncardiac
reason. Left ventricular diastolic volume index
was 226.9 ± 117.7 cm3/m2 before surgery and 134.9 ±
70.4 cm3/m2 at 6 months after surgery (n = 10). Factors
predictive for resolution of CHF included left ventricular
diastolic volume index < 250 cm3/m2 and systolic
volume index < 70 cm3/m2.
Conclusion and Clinical Relevance—Mitral valve
repair may resolve CHF in dogs with severe mitral
regurgitation, particularly in dogs that weigh > 10 kg
and are treated within 6 months of the onset of CHF.
(J Am Vet Med Assoc 2004;224:1941–1945)
Case Description—A 5-year-old male German Shepherd Dog was evaluated because of a 5-month history of progressive lethargy, weight loss, and heart failure.
Clinical Findings—On physical examination, bounding femoral pulses and systolic and diastolic murmurs were detected. Echocardiography revealed severe aortic valve insufficiency (AVI) and a large vegetative lesion on the aortic valve consistent with aortic valve endocarditis. The AVI velocity profile half-time was 130 milliseconds; the calculated peak systolic pressure gradient across the aortic valve was 64 mm Hg. Left ventricular diameter during diastole was 63.6 mm (predicted range, 40.2 to 42 mm) and during systole was 42.9 mm (predicted range, 25.4 to 27 mm). Systolic, diastolic, and mean arterial blood pressures were 120, 43, and 65 mm Hg, respectively.
Treatment and Outcome—To palliate severe AVI, the descending aorta was occluded (duration, 16.75 minutes) and heterotopic implantation of a porcine bioprosthetic heart valve in that vessel was performed. After surgery, systolic, diastolic, and mean arterial blood pressures were 115, 30, and 61 mm Hg, respectively, in the forelimb and 110, 62, and 77 mm Hg, respectively, in the hind limb. Within 6 months, the AVI velocity profile half-time had increased to 210 milliseconds, indicating diminished severity of AVI. After 24 months, the dog was able to engage in vigorous exercise; no pulmonary edema had developed since surgery.
Clinical Relevance—Heterotopic bioprosthetic heart valve implantation into the descending aorta during brief aortic occlusion appears feasible in dogs and may provide substantial palliation for dogs with severe AVI.
Objective—To compare outcome and intermediateterm
survival for dogs undergoing open surgical correction
of subvalvular aortic stenosis (SAS) with those
for dogs with SAS that did not undergo surgery.
Animals—44 dogs with congenital SAS.
Procedure—Maximum instantaneous systolic pressure
gradients were determined by use of Doppler
echocardiography. Cardiopulmonary bypass and open
surgical correction of SAS (membranectomy with or
without septal myectomy) was performed in 22 dogs,
whereas 22 dogs did not undergo surgical correction.
Cumulative survival was compared between surgical
and nonsurgical groups, using Kaplan-Meier nonparametric
analysis and a Mantel-Cox log-rank test.
Results—Initial systolic pressure gradients were not
significantly different for dogs undergoing surgery (128
± 55 mm Hg), compared with those that did not undergo
surgery (117 ± 57 mm Hg). Systolic pressure gradients
were significantly decreased after surgery in
dogs that underwent surgery (54 ± 27 mm Hg).
Cumulative survival was not significantly different
between dogs in the surgical and nonsurgical groups.
Censoring surgery-related mortality in the analysis still
did not reveal a significant difference in cumulative survival
between the surgical and nonsurgical groups.
Conclusion and Clinical Relevance—Despite
reductions in the systolic pressure gradient and possible
associated improvement in exercise tolerance, a
palliative benefit on survival was not documented in
dogs undergoing surgery for SAS. (J Am Vet Med