Quantification of mitral valve regurgitation in dogs with degenerative mitral valve disease by use of the proximal isovelocity surface area method

OBJECTIVE

To determine the within-day and between-day variability of regurgitant fraction (RF) assessed by use of the proximal isovelocity surface area (PISA) method in awake dogs with degenerative mitral valve disease (MVD), measure RF in dogs with MVD, and assess the correlation between RF and several clinical and Doppler echocardiographic variables.

DESIGN

Prospective study.

ANIMALS

6 MVD-affected dogs with no clinical signs and 67 dogs with MVD of differing severity (International Small Animal Cardiac Health Council [ISACHC] classification).

PROCEDURES

The 6 dogs were used to determine the repeatability and reproducibility of the PISA method, and RF was then assessed in 67 dogs of various ISACHC classes. Mitral valve regurgitation was also assessed from the maximum area of regurgitant jet signal-to-left atrium area (ARJ/LAA) ratio determined via color Doppler echocardiographic mapping.

RESULTS

Within- and between-day coefficients of variation of RF were 8% and 11%, respectively. Regurgitation fraction was significantly correlated with ISACHC classification and heart murmur grade and was higher in ISACHC class III dogs (mean +/- SD, 72.8 +/- 9.5%) than class II (57.9 +/- 20.1%) or I (40.7 +/- 19.2%) dogs. Regurgitation fraction and left atriumto-aorta ratio, fractional shortening, systolic pulmonary arterial pressure, and ARJ/LAA ratio were significantly correlated.

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggested that RF is a repeatable and reproducible variable for noninvasive quantitative evaluation of mitral valve regurgitation in awake dogs. Regurgitation fraction also correlated well with disease severity. It appears that this Doppler echocardiographic index may be useful in longitudinal studies of MVD in dogs.

Doppler echocardiography–derived evidence of pulmonary arterial hypertension in dogs with degenerative mitral valve disease: 86 cases (2001–2005)

OBJECTIVE

To determine the prevalence of Doppler echocardiography-derived evidence of pulmonary arterial hypertension (DEE-PAH) in dogs with mitral valve disease (MVD) classified according to the International Small Animal Cardiac Health Council (ISACHC) heart failure classification scheme and various echocardiographic and Doppler indices of MVD severity.

DESIGN

Retrospective case series.

ANIMALS

617 dogs examined from 2001 to 2005 with MVD in ISACHC classes I to III.

PROCEDURES

Dogs were examined echocardiographically. Criteria used for systolic and diastolic DEE-PAH were detection of high tricuspid (> or = 2.5 m/s) and telediastolic pulmonic (> or = 2.0 m/s) valvular peak regurgitant jet velocities, respectively, by use of continuous-wave Doppler echocardiography.

RESULTS

86 (13.9%) dogs with MVD had a diagnosis of DEE-PAH. Severity and prevalence of DEE-PAH increased with ISACHC class (3.0%, 16.9%, 26.7%, and 72.2% prevalences for ISACHC classes Ia, Ib, II, and III, respectively). A significant correlation between systolic or diastolic pulmonary arterial pressure and left atrial-to-aortic diameter ratio (LA/Ao) was detected. Doppler echocardiography-derived evidence of pulmonary arterial hypertension was detected in 18 dogs with values of LA/Ao within reference range, all of which had moderate (n = 2 dogs) or severe (16) mitral valve regurgitation on color Doppler imaging.

CONCLUSIONS AND CLINICAL RELEVANCE

The prevalence and degree of DEE-PAH were related to the severity of MVD. Changes associated with DEEPAH may be detected in early stages of the disease, but only in dogs with severe mitral valve regurgitation.

Mutation induction by difunctional alkylating agents in Neurospora crassa

The genetic characterization of ad-3 mutants of Neurospora crassa induced by two carcinogenic difunctional akylating agents, 1,2,4,5-diepoxypentane (DEP) and 1,2,7,8-diepoxyoctane (DEO), has shown that point mutations at the ad-3B locus have similar complementation patterns. In addition to the induction of point mutations, DEP induces a low frequency (7.5%) of multilocus deletions, whereas DEO induces an extremely high frequency (42.0%). The distribution of the different classes of ad-3 mutants and the frequency of multilocus deletion mutants among DEP-induced mutants are not significantly different from those induced by the monofunctional alkylating agents EI, EMS and ICR-177 at comparable forward-mutation frequencies. Moreover, the frequencies of DEP-induced ad-3B mutants showing allelic completion or having nonpolarized complementation patterns are similar to those of ad-3B mutants induced by monofunctional agents. It is suggested, therefore, that the mechanism of mutation-induction by DEP in N. crassa is similar to that of monofunctional alkylating agents. Mutation-induction by DEO probably results both from the mechanism of action of monofunctional alkylating agents and from inter-strand cross-linkage of the DNA molecular by the two functional epoxy groups.