Objectives: To evaluate the characteristics and survival of a recent population of cats with hypertrophic cardiomyopathy. Methods: Records at the Royal Veterinary College Queen Mother Hospital for Animals were searched for cats diagnosed with hypertrophic cardiomyopathy between 1997 and 2005. Referring veterinarians and owners were contacted to determine survival times. Results: Cats with hypertrophic cardiomyopathy were evaluated for population characteristics (n=127) and survival times (n=109). Overall median survival from date of hypertrophic cardiomyopathy diagnosis at the Queen Mother Hospital for Animals was 1276 days. Cats with hypertrophic cardiomyopathy were younger (P=0·009), and more likely to be male (P<0·001) compared to a hospital control group (n=1473), and Ragdolls were over‐represented (P<0·05). Characteristics associated with increased survival in univariate analysis included younger age (P=0·007), asymptomatic status (P<0·001), normal left atrial size (P<0·001) and presence of systolic anterior motion of the mitral valve (P=0·003). Systolic anterior motion was associated with asymptomatic status, and did not influence survival in asymptomatic cats or those in congestive heart failure. Age, left atrial size and breed were significantly associated with survival time in a multivariate analysis. Clinical Significance: Cats with hypertrophic cardiomyopathy and left atrial enlargement have a poorer prognosis. The positive influence of systolic anterior motion on survival is likely to be linked to its association with asymptomatic status.

Myocardial motion was quantified in normal cats (n = 25) and cats with hypertrophic cardiomyopathy (HCM) (n = 23) using the pulsed tissue Doppler imaging (TDI) technique. A physiologic nonuniformity was documented in the myocardial motion of normal cats, which was detected as higher early diastolic velocities, acceleration, and deceleration in the interventricular septum compared with the left ventricular free wall (LVFW). HCM cats exhibited lower early diastolic velocities, acceleration, and deceleration and also prolonged isovolumic relaxation time compared with normal cats. These differences were detected mainly along the longitudinal axis of the heart. A cutoff value of E' in the LVFW along the longitudinal axis >7.2 cm/s discriminated normal from HCM cats with a sensitivity of 92% and a specificity of 87%. The physiologic nonuniformity of myocardial motion during diastole was lost in affected cats. Systolic impairment (decreased late-systolic velocities in most segments along the longitudinal axis and decreased early systolic acceleration in both mitral annular sites) was evident in HCM cats irrespective of the presence of left ventricular outflow tract obstruction and congestive heart failure. Postsystolic thickening was recorded in the LVFW along the longitudinal axis only in affected cats (n = 6) and was another finding indicative of systolic impairment in the HCM of this species. This study identified both diastolic and systolic impairment in cats with HCM compared with normal cats. The study also documents the normal physiologic nonhomogeneity in myocardial motion in cats and the subsequent loss of this feature in the HCM diseased state.

The objective of this study was to determine the intraoperator, intraobserver, and interobserver repeatability in a series of conventional echocardiographic parameters and in some of the newer measurements of diastolic function, including color M-mode flow propagation velocity, isovolumic relaxation time and pulsed-wave Doppler tissue imaging velocities. Four healthy cats were each scanned five times over a 3-day period. The repeatability of these echocardiographic analyses was compared using Bland-Altman analysis (intraoperator repeatability). After a minimum of 5 weeks, one scan was randomly selected from each cat, and was remeasured by the original observer and the results compared using a standard paired Student's t-test (intraobserver repeatability). One scan from each cat was then randomly selected and two observers, with similar levels of experience, measured each of these scans. The repeatability of these echocardiographic analyses was compared using Bland-Altman analysis (interobserver repeatability). The conventional two-dimensional (2D), M-mode and spectral Doppler measurements were repeatable in both their acquisition and measurement by a single investigator; there was a greater degree of variation between the two observers. The predominant (S', E', and A') pulsed-wave Doppler tissue imaging velocities from the left apical four-chambered view, generally had a coefficient of variation of approximately 20% (range 9.62-34.08%). However, with pulsed-wave Doppler tissue imaging, velocities recorded during the isovolumic phases, the velocity of the tricuspid annulus, and the radial fiber velocity within the interventricular septum, frequently had coefficients of variation in excess of 20% and should therefore be interpreted with caution.

Myocardial motion was quantified in normal cats (n = 25) and cats with hypertrophic cardiomyopathy (HCM) (n = 23) using the pulsed tissue Doppler imaging (TDI) technique. A physiologic nonuniformity was documented in the myocardial motion of normal cats, which was detected as higher early diastolic velocities, acceleration, and deceleration in the interventricular septum compared with the left ventricular free wall (LVFW). HCM cats exhibited lower early diastolic velocities, acceleration, and deceleration and also prolonged isovolumic relaxation time compared with normal cats. These differences were detected mainly along the longitudinal axis of the heart. A cutoff value of E' in the LVFW along the longitudinal axis >7.2 cm/s discriminated normal from HCM cats with a sensitivity of 92% and a specificity of 87%. The physiologic nonuniformity of myocardial motion during diastole was lost in affected cats. Systolic impairment (decreased late-systolic velocities in most segments along the longitudinal axis and decreased early systolic acceleration in both mitral annular sites) was evident in HCM cats irrespective of the presence of left ventricular outflow tract obstruction and congestive heart failure. Postsystolic thickening was recorded in the LVFW along the longitudinal axis only in affected cats (n = 6) and was another finding indicative of systolic impairment in the HCM of this species. This study identified both diastolic and systolic impairment in cats with HCM compared with normal cats. The study also documents the normal physiologic nonhomogeneity in myocardial motion in cats and the subsequent loss of this feature in the HCM diseased state.

This study shows that hypertrophic cardiomyopathy cats have decreased myocardial velocity gradient during both diastole and systole and also altered myocardial motion during the two isovolumic periods. Myocardial velocity gradients recorded by colour M-mode tissue Doppler imaging can discriminate between the healthy and diseased myocardium.

We sought to assess the feasibility of recording the myocardial velocity gradients (MVGs) and mean myocardial velocities (MMVs) measured by color M-mode tissue Doppler imaging (TDI) in the free wall of unsedated normal cats (n = 18) with a 7.4-MHz probe equipped to record TDI images. The peak MVG and MMV values during the different phases of the cardiac cycle corresponded to certain color velocity patterns occurring in the left ventricular free wall (LVFW). Biphasic shifts were recorded in the tracings of both the MVG and MMV during early diastole (E1 and E2) as well as during the isovolumic relaxation (IVR) and isovolumic contraction (IVC) phases. Stepwise regression analysis showed that age was the only significant predictor for the peak MVG values during the 2nd phase of early diastole (E2) (r = -0.79, r2 = 0.63, and P < .001). The peak late diastolic MVG values were associated positively with age (r = 0.50, r2 = 0.25, and P < .05). The peak MMV values showed a negative association with age during E2 (r = -0.71, r2 = 0.50, and P < .001) as well as during early systole (Se) (r = -0.55, r2 = 0.30, and P < .05) and late systole (SI) (r = -0.62, r2 = 0.39, and P < .01). A positive association was found between age and the peak MMV values during late diastole (r = 0.54, r2 =- 0.29, and P < .05). The MVG values showed cyclic variations consistent with wall thickness changes. The accuracy of velocity determination and the spatial resolution of the system used were validated with a phantom. To our knowledge, this study is the 1st report of the application of this technique to the myocardium of cats,providing insights into the physiology of myocardial motion. It provides reference ranges of the peak MVG and MMV values for future studies of feline myocardial diseases.

We sought to assess the feasibility of recording the myocardial velocity gradients (MVGs) and mean myocardial velocities (MMVs) measured by color M-mode tissue Doppler imaging (TDI) in the free wall of unsedated normal cats (n = 18) with a 7.4-MHz probe equipped to record TDI images. The peak MVG and MMV values during the different phases of the cardiac cycle corresponded to certain color velocity patterns occurring in the left ventricular free wall (LVFW). Biphasic shifts were recorded in the tracings of both the MVG and MMV during early diastole (E1 and E2) as well as during the isovolumic relaxation (IVR) and isovolumic contraction (IVC) phases. Stepwise regression analysis showed that age was the only significant predictor for the peak MVG values during the 2nd phase of early diastole (E2) (r = -0.79, r2 = 0.63, and P < .001). The peak late diastolic MVG values were associated positively with age (r = 0.50, r2 = 0.25, and P < .05). The peak MMV values showed a negative association with age during E2 (r = -0.71, r2 = 0.50, and P < .001) as well as during early systole (Se) (r = -0.55, r2 = 0.30, and P < .05) and late systole (SI) (r = -0.62, r2 = 0.39, and P < .01). A positive association was found between age and the peak MMV values during late diastole (r = 0.54, r2 =- 0.29, and P < .05). The MVG values showed cyclic variations consistent with wall thickness changes. The accuracy of velocity determination and the spatial resolution of the system used were validated with a phantom. To our knowledge, this study is the 1st report of the application of this technique to the myocardium of cats,providing insights into the physiology of myocardial motion. It provides reference ranges of the peak MVG and MMV values for future studies of feline myocardial diseases.

Background: Double-chambered right ventricle (DCRV) is a frequently recognized cardiac congenital abnormality in humans. It has been described in dogs and in 1 cat. However systemic description of clinical and echocardiographic features of the disease in cats is currently lacking from the veterinary literature.Animals: Nine cats with DCRV are described.Results: The cats ranged from 4 months to 10 years of age. Eight cats at presentation were asymptomatic and 1 cat had chylothorax. In all cases echocardiography revealed abnormal fibromuscular bundles obstructing the mid-right ventricle, dividing the chamber into 2 compartments. The proximal right ventricular compartment was markedly hypertrophied, and right atrial dilation was usually present. The mean pressure gradient measured across the stenotic area was 130 6 50 mm Hg. Concurrent abnormalities included a ventricular septal defect (n 5 2); aortic malalignment, aortic insufficiency (n 5 1); and congenital peritoneal-pericardial diaphragmatic hernia (n 5 1). Two cats had systolic anterior motion of the mitral valve, one of which had concurrent left ventricular hypertrophy. Five cats have remained asymptomatic for a median period of 3.6 years (range, 3.3-5 years) and 3 cats have developed clinical signs associated with congestive heart failure (at 2, 3.3, and 9 years). One cat showed progressive lethargy and exercise intolerance and underwent partial ventriculectomy at the age of 2 years. This cat died during the operation with electromechanical dissociation.Conclusions: DCRV is a congenital cardiac abnormality that may be more common than previously recognized.