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Background: Papillary muscle hypertrophy can occur in conjunction with, or as the only indication of, hypertrophic cardiomyopathy or other diseases that result in left ventricular concentric hypertrophy (LVCH). Assessment of papillary muscle size is usually subjective because objective measures have not been reported., Hypothesis: The study hypothesis was that papillary muscle dimensions are different between normal cats and cats with LVCH., Animals: Echocardiograms from 44 normal cats and 40 cats with LVCH were included in the study., Methods: All measurements were taken from the right parasternal short-axis view at the level of the papillary muscles at end-diastole. Three methods were used to assess papillary muscle size: the area subtraction method, the direct area trace method, and the diameter method. Measurements were compared between cat groups and method comparisons were made among methods for area determination., Results: Cats with LVCH were older and had significantly greater left ventricular septal and free wall thicknesses and larger left atrial measurements than normal cats (P < .0006). Papillary muscle measurements were significantly greater by all measurement methods in cats with LVCH than in cats with normal echocardiograms (P < .0001). The area subtraction method and direct area trace method showed moderate agreement., Conclusions and Clinical Importance: Papillary muscle measurements were larger for LVCH cats than normal cats; however, some overlap was present. The establishment of these objective measures adds to the echocardiographic examination of cats.

Objective: To determine ECG and echocardiographic measurements in healthy anesthetized Grevy's zebras (Equus grevyi)., Animals: 20 healthy zebras., Procedures: Auscultation, base-apex ECG, and echocardiography were performed on anesthetized zebras., Results: Low-grade systolic murmurs were detected in the left basilar region in 4 of 20 zebras. Evaluation of ECGs from 19 zebras revealed sinus rhythm with a predominantly negative QRS complex and a mean +/- SD heart rate of 67 +/- 10 beats/min. Echocardiograms of sufficient image quality were obtained for 16 zebras. Interventricular septal thickness in diastole, left ventricular chamber in diastole and systole, left atrial diameter, and left ventricular mass were significantly and moderately correlated with estimated body weight (r values ranged from 0.650 to 0.884). Detectable swirling of blood in the right and sometimes the left ventricles was detected in 9 of 16 zebras, whereas physiologic regurgitation of blood was detected for the aortic valve in 3 zebras, pulmonary valve in 2 zebras, mitral valve in 2 zebras, and tricuspid valve in 1 zebra., Conclusions and Clinical Relevance: Results of this study provide reference information for use in the cardiac evaluation of anesthetized Grevy's zebras.

The objective of this study was to assess 2 noninvasive methods of measuring cardiac output (CO) in neonatal foals by comparing results to that of the lithium-dilution method. Ten neonatal foals were anesthetized and CO was manipulated by varying the depth of anesthesia and infusion of dobutamine. Concurrent CO measurements were obtained by lithium dilution (reference method), partial carbon dioxide (CO2) rebreathing, volumetric echocardiography (cubic, Teichholz, Bullet, area-length, and single and biplane modified Simpson formulas), and transthoracic Doppler echocardiography. Thirty pairs of lithium-dilution/noninvasive CO measurements were taken from the 10 foals. For each method, relative bias was calculated as a percentage of the average CO. Lithium determinations of CO ranged between 3.09 and 1 1.1 L/min (mean +/- SD = 6.39 +/- 2.1 L/min), resulting in cardiac indices ranging between 79.0 and 209 mL/kg/min (mean +/- SD = 131 +/- 35.9 mL/kg/min). Relative bias of Doppler echocardiography significantly increased (P < .05), whereas that of partial CO2 rebreathing significantly decreased (P = .03) with increasing CO. Other methods were not influenced by the level of CO. Among methods not influenced by the level of CO, relative bias of the Bullet method (-4.2 +/- 20.9%; limits of agreement -45.2 to 36.7%) was significantly lower (P < .05) than that of each of the other noninvasive methods evaluated. Volumetric echocardiography using the Bullet method provides an accurate and noninvasive estimate of CO in anesthetized neonatal foals and warrants investigation in critically ill conscious foals.

Abstract: Objective: The purpose of this study was to evaluate echocardiograms from normal cats for the presence of physiologic valve regurgitation (PVR). Background: PVR occurs commonly in normal dogs, however, the percentage of normal cats with PVR has not been previously reported. Animals, materials and methods: Echocardiograms were retrospectively and prospectively evaluated from clinically normal cats without echocardiographic evidence of cardiac disease. PVR was diagnosed if the valve was structurally normal and regurgitant color flow was subjectively trivial. The color jet area was expressed as a percentage of the chamber area. Results are expressed as mean±SD. Results: Retrospective study: The 46 cats were 2.1±1.5 years (range 0.3–7 years) and were purebred. Four cats (9%) had physiologic mitral regurgitation (PMR) (area of 4%). One cat (2%) had physiologic pulmonary regurgitation (PPR). Twenty-seven cats (57%) had physiologic tricuspid regurgitation (PTR) (area of 6±3% to 11±8% depending on view). Prospective study: The 58 cats were 4.9±2.8 years (range 1–12 years), weighed 5.2±1.2kg and were of various breeds. Three cats (5%) had PMR (area of 10±2%). One cat (2%) had PPR. Forty-one cats (71%) had PTR (area of 9±5% to 11±6% depending on view). Retrospective and prospective data were pooled (104 cats) and 7 cats (7%) had PMR, 2 cats (2%) had PPR and 68 cats (65%) had PTR. Conclusions: PTR is common in normal cats and the average regurgitant jet area is small compared to the chamber area. [Copyright &y& Elsevier]

Objective To investigate the negative chronotropic, antiarrhythmic, and obstruction-relieving effects of atenolol in cats with subclinical hypertrophic cardiomyopathy (HCM). Animals Seventeen cats with HCM. Methods Results for echocardiography, electrocardiography, Doppler blood pressure, and 24 h Holter monitoring were compared in cats before and 2–4 weeks after atenolol therapy (6.25–12.5 mg PO q 12 h). Results The left ventricular outflow tract maximum velocity (LVOT Vmax) decreased after atenolol administration (mean Vmax pre-treatment 3.3 m/s ± 1.8 m/s; post-treatment 1.6 m/s ± 1.0 m/s, p < 0.0001). Heart rate (HR) decreased after atenolol for all HR modalities. The total number of ventricular origin complexes (TotVent) and ventricular premature complexes (VPCs) decreased after atenolol. The VPCs decreased from a geometric mean of 61 complexes/24 h (range, 11–620 complexes/24 h) to 15 complexes/24 h (range, 1–1625 complexes/24 h) (p < 0.0001). Murmur grade decreased after atenolol from a median grade of 3/6 to 2/6 (p < 0.0001). The systolic blood pressure did not change (mean pre-treatment 130 mmHg ± 16 mmHg, mean post-treatment 123 mmHg ± 20 mmHg, p = 0.2). Conclusion Atenolol decreases HR, murmur grade, and LVOT obstruction, and to a lesser degree, frequency of ventricular ectopy, in cats with subclinical HCM. Further studies are needed to determine if sudden cardiac death or long-term outcome is influenced by atenolol administration. [ABSTRACT FROM AUTHOR]