Systolic blood pressure in cats with diabetes mellitus

OBJECTIVE: To determine the prevalence of systemic hypertension in cats with diabetes mellitus and establish ranges for echocardiographic variables in diabetic cats. DESIGN: Prospective study. ANIMALS: 14 cats with diabetes mellitus and 19 healthy control cats. PROCEDURE: Systolic blood pressure was measured indirectly with a noninvasive Doppler technique. Ophthalmic and echocardiographic examinations were performed, and urine protein concentration was measured. Cats were considered to have hypertension if they had systolic blood pressure > 180 mm Hg and at least 1 other clinical abnormality typically associated with hypertension (eg, hypertensive retinopathy, left ventricular hypertrophy, or proteinuria). RESULTS: None of the diabetic or control cats had systolic blood pressure > 180 mm Hg. One diabetic cat had left ventricular hypertrophy, but systolic blood pressure was 174 mm Hg. None of the cats had evidence of hypertensive retinopathy or proteinuria. Mean values for echocardiographic variables for the diabetic cats were not significantly different from published values for healthy cats. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that hypertension does not occur or occurs in only a small percentage of cats with diabetes mellitus.     

Effect of amlodipine on echocardiographic variables in cats with systemic hypertension

Left ventricular hypertrophy signals a poor prognosis in hypertensive humans. Cardiac disease is common in cats with systemic hypertension. The aims of this study were to characterize the echocardiographic findings of cats with systemic hypertension and to determine if reducing the degree of hypertension is associated with resolution of cardiac hypertrophy. Echocardiographic examinations were performed on 19 cats with naturally occurring systemic hypertension. Fourteen of these cats were subsequently studied after a minimum of 3 months of treatment with the antihypertensive agent amlodipine. Hypertensive cats had a significantly thicker interventricular septum in both systole and diastole, thicker left ventricular free wall in both systole and diastole, and larger left atrium compared to the published normal values and 74% (14/19) of the cats met criteria for left ventricular hypertrophy (diastolic septal or free-wall thickness > 0.60 cm). Systolic blood pressure was lower after treatment (217 +/- 25 mm Hg, range: 180-275 mm Hg; and 142 +/- 27 mm Hg, range: 90-200 mm Hg). No difference was found in any of the echocardiographic measurements between the untreated and treated cats, although more cats had ventricular hypertrophy before treatment (11/14) than after initiating amlodipine (6/14; P = .006). Ventricular hypertrophy is common in hypertensive cats and may resolve after the initiation of amlodipine.     

Blood pressure assessment in healthy cats and cats with hypertensive retinopathy

OBJECTIVE: To determine whether there was an association between hypertensive retinopathy and high systolic, diastolic, and mean arterial blood pressures in cats. ANIMALS: 181 cats. PROCEDURE: Systolic, diastolic, and mean arterial blood pressures were measured by use of a noninvasive oscillometric technique. The range of blood pressure measurements in healthy cats from various age groups was determined. Associations among systolic, diastolic, and mean arterial blood pressure; hypertensive retinopathy; hyperthyroidism; left ventricular cardiac hypertrophy; chronic renal failure; and serum biochemical abnormalities were determined. RESULTS: All blood pressure measurements increased with age in healthy cats. The frequency of hypertensive retinopathy also increased with age and with blood pressure, and hypertensive retinopathy was particularly found in cats with systolic blood pressures > 168 mm Hg. There was an increased risk for hypertensive retinopathy in cats that were female, > 10 years old, and neutered. The risk of chronic renal failure also increased as blood pressure, particularly systolic blood pressure, increased. CONCLUSIONS AND CLINICAL RELEVANCE: Hypertensive retinopathy was common in cats > or = 10 years of age and was associated with systolic blood pressures > 168 mm Hg when measured by the noninvasive oscillometric technique.     

A comparison of CAT Doppler and oscillometric Memoprint machines for non-invasive blood pressure measurement in conscious cats

Indirect blood pressure measurements were compared in 28 conscious cats using Doppler and oscillometric blood pressure-measuring devices. Ten cats were used to compare Doppler measurements between two examiners and 18 cats were used to compare Doppler and oscillometric measurements. The Doppler machine obtained systolic and diastolic blood pressure readings in 100% and 51% of attempts, respectively. With the oscillometric machine, systolic and diastolic blood pressure readings were obtained in 52% of the attempts. With the Doppler, measures of mean systolic blood pressure between two examiners were positively correlated, but there was no correlation for diastolic blood pressure measures. When comparing the results obtained by Doppler and oscillometric machines there was no significant difference between mean systolic blood pressure readings, but the oscillometric machine produced significantly higher estimates of diastolic blood pressure. In both cases, the standard deviations for the oscillometric machine were considerably larger than those for the Doppler machine. The first reading of systolic blood pressure obtained with the Doppler machine was an excellent predictor of the mean of five readings, but this was not so for the oscillometric machine. It took less than 5 min to obtain five readings in 37.5% of cases with the Doppler machine but this was true for only 5% of cases with the oscillometric machine. Two cats with ophthalmological lesions consistent with systemic hypertension were identified. In these two patients, systolic blood pressure measurements were between 200 and 225 mmHg when measured by Doppler, and between 140 and 150 mmHg when measured by the oscillometric machine. This suggests that a lower reference range for normal systolic blood pressure values should be used for the oscillometric device.     

Spontaneous Systemic Hypertension in 24 Cats

Twenty-four cats with spontaneous systemic hypertension were retrospectively studied. Blood pressure (BP) was measured indirectly by the Doppler technique in 17 cats (mean systolic 219.4 ± 43.2 mm Hg) and directly by femoral arterial puncture in 15 cats (mean systolic/diastolic 233.2 ± 40.9/148.1 ± 28.7 mm Hg). All cats had bilateral retinal hemorrhages and/or detachments. Twenty cats presented because of blindness. Other presenting signs included polyuria/polydipsia, weight loss, neurological signs, and/or epistaxis. Diagnostic tests were performed to determine the presence and the cause of any secondary organ damage. Common findings included retinal hemorrhages/ detachments, low-grade systolic murmurs, cardiomegaly with left ventricular hypertrophy (LVH), small kidneys, mild azotemia, and urine specific gravity ≤ 1.020. Only 3 cats had hyperthyroidism. One cat was transiently diabetic. Necropsies on 2 cats with neurological signs showed nephrosclerosis, arteriosclerosis, and multifocal cerebral hemorrhages. Twenty cats were treated with diuretics, β- adrenergic antagonists, and/or an angiotensin converting enzyme (ACE) inhibitor. One cat was treated with methimazole only, and 1 was treated with insulin transiently. The median survival of the 24 cats was 18 months. Response to therapy did not appear to have an impact on survival time.     

Cardiovascular effects of a high dose of romifidine in propofol-anesthetized cats

OBJECTIVE: To determine the hemodynamic effects of IM administration of romifidine hydrochloride in propofol-anesthetized cats. ANIMALS: 15 adult domestic shorthair cats. PROCEDURE: Cats were randomly assigned to receive romifidine (0, 400, or 2,000 microg/kg, IM). Cats were anesthetized with propofol and mechanically ventilated with oxygen. The right jugular vein, left carotid artery, and right femoral artery and vein were surgically isolated and catheterized. Heart rate; duration of the PR, QRS, and QT intervals; mean pulmonary artery pressure; mean right atrial pressure; systolic, diastolic, and mean arterial pressures; left ventricular systolic pressure; left ventricular end-diastolic pressure; and cardiac output were monitored. Systemic vascular resistance, rate of change of left ventricular pressure, and rate pressure product were calculated. Arterial and venous blood samples were collected anaerobically for determination of pH and blood gas tensions (Po2 and Pco2). RESULTS: Administration of romifidine at 400 and 2,000 microg/kg, IM, decreased heart rate, cardiac output, rate of change of left ventricular pressure, rate pressure product, and pH. Arterial and pulmonary artery pressures, left ventricular pressure, left ventricular end-diastolic pressure, and right atrial pressure increased and then gradually returned to baseline values. Arterial blood gas values did not change, whereas venous Pco2 increased and venous Po2 decreased. Significant differences between low and high dosages were rare, suggesting that the dosages investigated produced maximal hemodynamic effects. CONCLUSIONS AND CLINICAL RELEVANCE: Romifidine produces cardiovascular effects that are similar to those of other alpha2-agonists. High dosages of romifidine should be used with caution in cats with cardiovascular compromise.     

Pulsed tissue Doppler imaging in normal cats and cats with hypertrophic cardiomyopathy

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.     

Hypertension in Cats With Chronic Renal Failure or Hyperthyroidism

The Doppler ultrasonic recording technique was used to measure systolic and diastolic blood pressures indirectly in 28 cats with naturally occurring renal failure, 39 cats with hyperthyroidism, and 33 clinically normal cats. The mean systolic and diastolic blood pressures in the normal cats were 118.4 +/- 10.6 mm Hg and 83.8 +/- 12.2 mm Hg, respectively. In the cats with chronic renal failure, both the systolic (146.6 +/- 25.4 mm Hg) and diastolic (96.6 +/- 15.2 mm Hg) blood pressures were significantly higher (P less than 0.0001 and P less than 0.01, respectively) than in the normal cats. Elevations in systolic and/or diastolic blood pressure were recorded in 17 (61%) of the 28 cats with chronic renal failure. In the 39 untreated hyperthyroid cats, both the mean systolic (167.9 +/- 28.9 mm Hg) and diastolic (111.6 +/- 21.5 mm Hg) pressures also were significantly higher (P less than 0.0001) than normal. Increased systolic and/or diastolic blood pressure was recorded in 34 (87%) of the 39 hyperthyroid cats. In seven cats with hyperthyroidism that were reevaluated two to four months after successful treatment of the hyperthyroid state, there was a significant fall in mean systolic pressure (P less than 0.05) from a pretreatment value of 159.5 +/- 15.4 mm Hg to a posttreatment value of 132.0 +/- 1.62 mm Hg. Overall, the results of this study indicate that mild to moderate hypertension is common in cats with chronic renal failure and in cats with untreated hyperthyroidism. In addition, the hypertension appears to be reversible following successful treatment of the hyperthyroid state.     

Spontaneous feline hypertension: clinical and echocardiographic abnormalities,and survival rate

Systemic hypertension was diagnosed in 58 of 188 untreated cats referred for evaluation of suspected hypertension-associated ocular, neurologic. cardiorespiratory, and urinary disease, or diseases frequently associated with hypertension (hyperthyroidism and chronic renal failure). Hypertensive cats were significantly older than normotensive subjects (13.0 +/- 3.5 years versus 9.6 +/- 5.0 years; P < .01), and had a greater prevalence of retinal lesions (48 versus 3%; P < .001), gallop rhythm (16 versus 0%; P < .001), and polyuria-polydipsia (53 versus 29%: P < .01). Blood pressure was significantly higher (P < .001) in cats with retinopathies (262 +/- 34 mm Hg) than in other hypertensive animals (221 +/- 34 mm Hg). Hypertensive cats had a thicker interventricular septum (5.8 +/- 1.7 versus 3.7 +/- 0.64 mm; P < .001) and left ventricular free wall (6.2 +/- 1.6 versus 4.1 +/- 0.51 mm; P < .001) and a reduced diastolic left ventricular internal diameter (13.5 +/- 3.2 versus 15.8 +/- 0.72 mm; P < .001) than control cats. Left ventricular geometry was abnormal in 33 of 39 hypertensive subjects. No significant difference was found in age or blood pressure at the initial visit between cats that died or survived over a 9-month period after initial diagnosis of hypertension. Mean survival times were not significantly different between hypertensive cats with normal and abnormal left ventricular patterns. Further prospective studies are needed to clearly identify the factors involved in survival time in hypertensive cats.     

Mitral valve dysplasia in a cat causing reversible left ventricular hypertrophy and dynamic outflow tract obstruction

A 6-month-old male European shorthair cat was examined because of a 2/6 systolic left apical cardiac murmur. Echocardiography revealed severe concentric left ventricular hypertrophy and severe dynamic left ventricular outflow tract obstruction (pressure gradient of 85 mmHg) caused by systolic anterior motion (SAM) of the septal mitral valve leaflet. After 2 months of oral treatment with atenolol, the cardiac murmur had disappeared. Echocardiography showed only slight thickening of the interventricular septum and resolution of the pressure gradient. The cat was discharged and its owner was advised to continue atenolol lifelong. Echocardiographic findings of a combination of left ventricular concentric hypertrophy and dynamic left ventricular outflow tract obstruction can be caused by hypertrophic obstructive cardiomyopathy (HOCM) or mitral valve dysplasia in the absence of hypertension and fixed aortic stenosis. In the case of HOCM, left ventricular hypertrophy is the primary process. In the case of mitral valve dysplasia, systolic anterior motion of the mitral valve is the primary problem, which leads to dynamic left ventricular outflow tract obstruction and ultimately to left ventricular concentric hypertrophy, due to pressure overload. If the left ventricular outflow tract obstruction is reduced with an oral beta-receptor blocker the secondary left ventricular hypertrophy may resolve. This would not happen in the case of hypertrophic obstructive cardiomyopathy. To the best of the authors' knowledge, this is the first documented case of severe dynamic left ventricular outflow tract obstruction and severe left ventricular hypertrophy in a cat successfully treated with oral atenolol.     

Colour M-mode tissue Doppler imaging in healthy cats and cats with hypertrophic cardiomyopathy

OBJECTIVES: To determine whether decreased diastolic and systolic myocardial velocity gradient between the endocardium and the epicardium exist in the left ventricle of cats with hypertrophic cardiomyopathy. METHODS: Myocardial velocity gradient and mean myocardial velocities were measured by colour M-mode tissue Doppler imaging in the left ventricular free wall of 20 normal cats and 17 cats with hypertrophic cardiomyopathy. RESULTS: The peak myocardial velocity gradient (sec(-1)) during the first (E1) (5.71+/-1.75 versus 11.38+/-3.1, P<0.001) and second phase (E2) (3.09+/-1.53 versus 7.02+/-3.1, P=0.005) of early diastole and also the maximum early diastolic myocardial velocity gradient (Emax) (6.12+/-2.1 versus 10.76+/-3.2, P<0.001) were reduced in cats with hypertrophic cardiomyopathy compared with normal cats. Peak myocardial velocity gradient during early systole (Se) was lower in affected cats than in normal cats (6.26+/-2.08 versus 8.67+/-2.83, P=0.006). Affected cats had a lower peak mean myocardial velocities (mm/s) during the two isovolumic periods (IVRb and IVCb) compared with normal cats (2.97+/-6.76 versus 12.74+/-5.5 and 22.28+/-9.96 versus 38.65+/-10.1, P<0.001, respectively). CLINICAL SIGNIFICANCE: 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.     

Quantification of left ventricular diastolic wall motion by Doppler tissue imaging in healthy cats and cats with cardiomyopathy

OBJECTIVE: To assess Doppler tissue imaging (DTI) for evaluating left ventricular diastolic wall motion in healthy cats and cats with cardiomyopathy. ANIMALS: 20 healthy cats, 9 cats with hypertrophic cardiomyopathy (HCM), and 9 cats with unclassified cardiomyopathy (UCM). PROCEDURE: A pulsed wave DTI sample gate was positioned at a subendocardial region of the left ventricular free wall in the short axis view and at the lateral mitral annulus in the apical 4-chamber view. Indices of diastolic wall motion were measured, including peak diastolic velocity (PDV), mean rate of acceleration and deceleration of the maximal diastolic waveform (MDWaccel and MDWdecel, respectively), and isovolumetric relaxation time (IVRT). RESULTS: The PDV of cats with HCM and 6 of 9 cats with UCM was significantly decreased, compared with that of healthy cats. In the 3 cats with UCM that had a PDV that was not different from healthy cats, MDWaccel and MDWdecel were greater, and IVRT was shorter than those of healthy cats. The IVRT in cats with HCM was longer than that of other cats. CONCLUSIONS AND CLINICAL RELEVANCE: Indices of diastolic function in cats with HCM, and in many cats with UCM, differed from those of healthy cats and were similar to those reported in humans with HCM and restrictive cardiomyopathy, respectively. However, the hemodynamic abnormality was not the same for all cats with UCM; some cats with an enlarged left atrium and a normal left ventricle (ie, UCM) had abnormal left ventricular wall motion consistent with restrictive cardiomyopathy while others did not.     

Natural history of hypertrophic cardiomyopathy and aortic thromboembolism in a family of domestic shorthair cats

A feline domestic shorthair queen and her 3 offspring were all diagnosed with asymptomatic hypertrophic cardiomyopathy (HCM). The family has been followed for 13 years, and 3 cats have died of aortic thromboembolism (ATE). This communication documents the long-term progression of HCM in these cats that presented with mild left ventricular hypertrophy and hyperdynamic systolic ventricular function, developed progressive left atrial enlargement, and eventually resulted in hypodynamic left ventricular systolic function with relative left ventricular chamber dilation at the time of ATE.     

Doppler echocardiographic effects of medetomidine on dynamic left ventricular outflow tract obstruction in cats

OBJECTIVE: To evaluate the effects of medetomidine on dynamic left ventricular outflow tract (LVOT) obstruction in cats with left ventricular hypertrophy. DESIGN: Clinical trial. ANIMALS: 6 domestic shorthair cats with echocardiographic evidence of dynamic LVOT obstruction. PROCEDURE: Cats were restrained in lateral recumbency, and baseline M-mode and Doppler echocardiographic examinations were performed. An ECG was recorded continuously, and blood pressure was measured indirectly with Doppler instrumentation. Medetomidine (20 microg/kg 19.1 microg/lb]) was then administered i.m., and examinations were repeated 15 minutes later. RESULTS: Significant decreases in heart rate, LVOT velocity, and the LVOT pressure gradient were documented following medetomidine administration. After adjusting for the effects of heart rate by ANCOVA, there were no significant differences in any other systolic or diastolic indices of left ventricular function. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that administration of medetomidine to cats with dynamic LVOT obstruction may result in elimination of outflow tract obstruction; medetomidine may be a suitable sedative and analgesic agent in this subpopulation of cats.     

Effects of the calcium channel antagonist amlodipine in cats with surgically induced hypertensive renal insufficiency

OBJECTIVE: To determine whether amlodipine besylate decreases systemic arterial blood pressure (BP) and reduces the prevalence of complications in cats with induced hypertensive renal insufficiency. ANIMALS: 20 cats with partial nephrectomy. PROCEDURE: Following reduction in renal mass, 10 cats were administered 0.25 mg of amlodipine/kg, PO, q 24 h (group A). Ten cats served as a control group (group C). Systolic BP (SBP), diastolic BP (DBP), and mean BP (MBP), physical activity, and pulse rate were measured continuously for 36 days by use of radiotelemetric devices. RESULTS: Compared with values for clinically normal cats, SBP, DBP, and MBP were significantly increased in cats of group C. Cats in group A had significant reductions in SBP, DBP, and MBP, compared with values for cats in group C. Albuminuria but not urine protein-to-creatinine ratio was significantly correlated (R2 = 0.317) with SBP in hypertensive cats. Prevalence of ocular lesions attributable to systemic hypertension in group C (7 cats) was greater than that observed in group A (2). Two cats in group C were euthanatized on day 16 because of nuerologic complications attributed to systemic hypertension. One normotensive cat in group A was euthanatized because of purulent enteritis of unknown cause on day 27. CONCLUSIONS AND CLINICAL RELEVANCE: Amlodipine had an antihypertensive effect in cats with coexistent systemic hypertension and renal insufficiency. Its use may improve the prognosis for cats with systemic hypertension by decreasing the risk of ocular injury or neurologic complications induced by high BP.     

Echocardiographic and radiographic changes associated with systemic hypertension in cats

The purpose of this study was to assess the effects of systemic hypertension (SHT) on echocardiographic and radiographic cardiovascular variables in affected cats compared with healthy geriatric cats. Secondary objectives were to determine whether there were any relationships between these findings and age or systolic blood pressure (SBP). Fifteen healthy cats (>8 years of age with normal SBP) and 15 hypertensive cats (SBP > 180 mm Hg) were studied. Each cat was evaluated for standard echocardiographic parameters and 4 different aortic root dimensions. Seventeen variables were measured from right lateral and dorsoventral radiographic views. Left ventricle wall thickness was greater in the SHT group (5.1 +/- 0.9 mm) than in the healthy cats (4.2 +/- 0.5 mm). Left ventricular hypertrophy in the SHT cats often was not severe, and mean measures were considered normal. Some cats had asymmetrical septal hypertrophy (ASH) in the basilar portion of the septum as determined from the 2-dimensional view of the left ventricular outflow tract. ASH was greater in cats with SHT. Comparisons of the proximal ascending aorta indicated the presence of dilatation in the SHT cats, and comparison of the ascending aorta to the aortic annulus was helpful in differentiating between the 2 groups. The distal aortic root measurements and ratios evaluated by echocardiography were significantly different between the 2 groups of cats (P = .0001) and were significantly correlated with SBP (P = .0001) but not age (P > .3).     

Effects of saffan on cardiopulmonary function in healthy cats.

The effects of saffan on cardiopulmonary function were evaluated in eight healthy adult cats. Measured values were cardiac output by thermodilution, heart rate by electrocardiogram, arterial blood gases, respiratory rate and systolic, diastolic and mean arterial blood pressures by arterial catheterization. Calculated values included cardiac index, stroke volume and systemic vascular resistance. Statistical analysis employed paired t-tests comparing pre saffan anesthetic induction and post saffan anesthetic parameters over a 120 minute time sequence. Thirty min after saffan induction, significant depression in cardiac output was evident while stroke volume was significantly depressed at 45 and 60 min, systolic blood pressure at 15 min and respiratory rate at 5, 10 and 15 min. No significant changes occurred in cardiac index, heart rate, arterial blood gases, diastolic and mean arterial blood pressure or systemic vascular resistance. It was concluded that saffan causes significant depression of cardiopulmonary function in normal adult cats.     

Increased mean arterial pressure and aldosterone-to-renin ratio in Persian cats with polycystic kidney disease

Polycystic kidney disease (PKD) in Persian cats has been increasingly reported and compared to human autosomal dominant polycystic kidney disease (ADPKD) in the last decade. In cats, however, few studies have dealt with the occurrence and hormonal determinants of hypertension, one of the most common extrarenal manifestations of ADPKD in humans. The purpose of this study was to compare Persian cats >4 years old with PKD to unaffected control cats with regard to blood pressure (BP), plasma renin activity (PRA), serum aldosterone concentration, plasma atrial natriuretic peptide (ANP) concentration, and aldosterone-to-renin ratio (ARR). Three gender- and age-matched groups were studied, each consisting of 7 cats: (1) a control group without cysts, (2) a group with mild PKD, and (3) a group with severe PKD (multiple cysts and renal enlargement). Mild renal insufficiency was found in only 1 of 14 cats with PKD. Cats with PKD had a higher mean arterial pressure (P = .04) and more often had a high ARR (P = .047) than did control cats. Tendencies toward higher diastolic and systolic arterial pressures (DAPs and SAPs, respectively) and lower PRAs were observed in cats with PKD compared to controls (.05 < P < or = .1). No significant differences were found between the groups in serum aldosterone and plasma ANP concentrations. None of the cats had echocardiographic evidence of cardiac hypertrophy. In conclusion, cats with PKD had a minor increase in mean arterial pressure compared to control cats, and half of the cats had a high ARR.     

PULMONARY HYPERTENSION IN DOGS WITH MITRAL REGURGITATION ATTRIBUTABLE TO MYXOMATOUS VALVE DISEASE

Pulmonary hypertension has been associated with mitral insufficiency caused by chronic degenerative valve disease in dogs. Our aim was to search for associations between left atrial to aortic root ratio, end‐systolic and end‐diastolic volume indices, and changes in the right ventricular to right atrial pressure gradient as estimated by the peak velocity of tricuspid regurgitation in dogs with chronic degenerative valve disease and different classes of heart failure. Dogs, for which follow‐up was available were evaluated for changes in the right ventricular to right atrial systolic pressure gradient over time. Three hundred and forty‐four dogs were studied; 51 in the International Small Animal Cardiac Health Council class 1a, 75 in class 1b, 113 in class 2, 97 in class 3a, and 8 in class 3b. The mean values for right ventricular to right atrial systolic pressure gradient, end‐systolic volume index, end‐diastolic volume index, and left atrial to aortic ratio were 49.2 ± 17.1 mmHg, 149.12 ± 60.8 and 37.7 ± 21.6 ml/m², and 1.9 ± 0.5, respectively. A weak positive correlation was found between the right ventricular to right atrial systolic pressure gradient and the left atrial to aorta ratio (r=0.242, P<0.0001), end‐diastolic volume index (r=0.242, P<0.0001), and end‐systolic volume index (r=0.129, P<0.001). Follow up was available for 49 dogs. Of these, 18 had an increased, 12 a decreased, and 19 a stable right ventricular to right atrial systolic pressure gradient despite therapy. The equivalence point between the sensitivity and specificity curves of about 80% in the coincident point corresponded to a right ventricular to right atrial systolic pressure gradient of 48 mmHg. Our results suggest an association between the progressive nature of chronic degenerative mitral valve disease and pulmonary hypertension. It is of clinical interest that, with a right ventricular to right atrial systolic pressure gradient pressure gradient at or above 48 mmHg, pulmonary hypertension does not appear to improve despite therapy targeted at lowering the left atrial load.     

M-mode echocardiographic measurements in nonanesthetized healthy cats: effects of body weight, heart rate, and other variables

Body weight, heart rate, and 19 M-mode echocardiographic variables were measured in 41 nonanesthetized healthy cats. Estimated limits were determined for the echocardiographic variables, and each variable was then correlated to body weight, heart rate, and the 18 other variables. A significant (P less than 0.05) positive correlation to body weight was found with aortic diameter, left atrial dimension, septal and left ventricular systolic and left ventricular diastolic wall thicknesses, and left and right ventricular diastolic and right ventricular systolic internal dimensions. Significant inverse correlation (P less than 0.05) to heart rate was found with body weight, left ventricular systolic and diastolic and right ventricular systolic internal dimensions, left atrial dimension, left atrial dimension to aortic ratio, mitral valve E point to ventricular septal separation, and left ventricular ejection time. Left ventricular shortening fraction in the short axis and velocity of circumferential fiber shortening were significantly correlated (P less than 0.05) to heart rate. Significant correlation (P less than 0.05) was also found between many echocardiographic variables.