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- Author or Editor: Karsten E. Schober x
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Abstract
Objectives
To investigate the effect of ammonium chloride-induced urine acidification on acid-base status (ABS) of blood, plasma, and erythrocytes, and to compare the diagnostic value of acid-base analysis for erythrocytes with that for blood and plasma.
Design
Ammonium chloride (100 mg/kg of body weight) was administered orally every 12 hours for 8 consecutive days. The ABS was determined daily in venous blood, plasma, and lysed, packed erythrocytes (erythrolysate) and in urine. In plasma and erythrocytes, concentrations of sodium (Na+) and potassium (K+) were analyzed.
Animals
16 clinically normal (8 treated and 8 control) dogs.
Procedure
The acid-base analysis (standard pH, standard bicarbonate concentration, base excess, and carbon dioxide tension) in blood, plasma, and erythrocytes was determined by use of the CO2, O2 gas equilibration method. Determination of urine ABS (pH, concentrations of acids and bases, net acid-base excretion, and baseacid quotient) was performed by titration methods. Determination of concentrations of Na+ and K+ in erythrocytes was performed by flame photometry, and in plasma, by use of ion-specific electrodes.
Results
Ammonium chloride caused metabolic acidosis in blood and plasma, but no change of ABS in erythrocytes. The concentrations of K+ in plasma and erythrocytes did not change in treated dogs; however, the concentrations of Na+ in plasma and erythrocytes decreased significantly (P <0.05) after ammonium chloride administration. Urinary acid excretion increased significantly (P<0.05) in treated dogs; urine pH was between 4.51 and 5.49 at all times.
Conclusions
Ammonium chloride administration (100 mg/kg, PO, q 12 h) causes substantial blood and urine acidification but does not influence erythrocyte ABS. In this study, determination of erythrocyte ABS did not provide any additional benefit in diagnosing metabolic acidosis, compared with analysis of blood. (Am J Vet Res 1996; 57:743–749)
Abstract
Objective—To determine the influence of age, body weight (BW), heart rate (HR), sex, and left ventricular shortening fraction (LVSF) on transmitral and pulmonary venous flow in clinically normal dogs.
Animals—92 client-owned dogs 3 months to 19 years old.
Procedure—Transthoracic Doppler echocardiography recordings of transmitral flow and pulmonary venous flow were obtained in conscious unsedated dogs. Influence of age, BW, HR, sex, and LVSF on diastolic variables was assessed, using statistical methods such as ANOVA on ranks and univariate and multivariate forward stepwise linear regression analyses.
Results—Age significantly influenced isovolumic relaxation time (IVRT; r = 0.56), ratio between peak velocity of the early diastolic mitral flow wave-to-peak velocity of late diastolic mitral flow wave (E:A; r = –0.44), deceleration time of early diastolic mitral flow (DTE; r = 0.26), and peak velocity of atrial reversal pulmonary venous flow wave (AR-wave; r= 0.37). Significant changes of mitral inflow and pulmonary venous flow variables were evident only in dogs > 6 and > 10 years old, respectively. Body weight significantly influenced DTE ( r = 0.63), late diastolic flow duration ( r= 0.60), and AR duration ( r= 0.47), whereas HR significantly affected DTE ( r = –0.34), IVRT ( r= –0.33), and peak velocity of AR ( r= 0.24). Sex or LVSF (range 22 to 48%) did not influence any echocardiographic variables.
Conclusions and Clinical Relevance—Age, BW, and HR are important factors that affect filling of the left atrium and left ventricle in clinically normal dogs. (Am J Vet Res 2001;62:1447–1454)
Abstract
Objective—To compare echocardiographic indices of myocardial strain with invasive measurements of left ventricular (LV) systolic function in anesthetized healthy dogs.
Animals—7 healthy dogs.
Procedures—In each anesthetized dog, preload and inotropic conditions were manipulated sequentially to induce 6 hemodynamic states; in each state, longitudinal, radial, and global strains and strain rate (SR), derived via 2-D speckle-tracking echocardiography, were evaluated along with conventional echocardiographic indices of LV function and maximum rate of rise (first derivative) of LV systolic pressure (LV+dp/dtmax). Catheter-derived and echocardiographic data were acquired simultaneously. Partial and semipartial correlation coefficients were calculated to determine the correlation between LV+dp/dtmax and each echocardiographic variable. Global longitudinal strain was compared with conventional echocardiographic indices via partial correlation analysis.
Results—All myocardial segments could be analyzed in all dogs. Significant semipartial correlations were identified between conventional echocardiographic strain indices and LV+dp/dtmax. Correlation coefficients for longitudinal deformation and global strain, segmental longitudinal strain, and segmental SR were −0.773, −0.562 to −0.786, and −0.777 to −0.875, respectively. Correlation coefficients for radial segments and strain or SR were 0.654 to 0.811 and 0.748 to 0.775, respectively. Correlation coefficients for traditional echocardiographic indices and LV+dp/dtmax (−0.586 to 0.821) and semipartial correlation coefficients for global strain and echocardiographic indices of LV systolic function (−0.656 [shortening fraction], −0.726 [shortening area], and −0.744 [ejection fraction]) were also significant.
Conclusions and Clinical Relevance—Results indicated that LV systolic function can be predicted by myocardial strain and SR derived via 2-D speckle-tracking echocardiographic analysis in anesthetized healthy dogs.
Abstract
Objective—To assess the feasibility, describe the techniques, and determine the reliability of transthoracic echocardiography for characterization of left atrial (LA) size and LA mechanical function in horses.
Animals—6 healthy adult horses.
Procedures—Repeated echocardiographic examinations were performed independently by 2 observers in standing, unsedated horses by use of 2-dimensional echocardiography, pulsed-wave flow Doppler, and tissue Doppler imaging (TDI) techniques. Test reliability was determined by estimating measurement variability, within-day interobserver variability, and between-day inter- and intraobserver variability of all echocardiographic variables. Variability was expressed as the coefficient of variation (CV) and the absolute value below which the difference between 2 measurements will lie with 95% probability.
Results—Most echocardiographic variables of LA size had low overall variability (CV, < 15%). Among the 2-dimensional indices of LA mechanical function, area-based and volume-based ejection phase indices had moderate between-day variability (CV usually < 25%). Transmitral Doppler flow indices were characterized by low to high between-day variability (CV, 6% to 35%). The TDI wall motion velocities had high between-day variability (CV, > 25%), whereas most TDI-derived time intervals had low variability (CV, < 15%).
Conclusions and Clinical Relevance—LA size and mechanical function can be reliably assessed in standing, unsedated horses by use of 2-dimensional echocardiography, transmitral blood flow velocity profiles, and analyses of LA wall motion by use of TDI. These results may provide useful recommendations for echocardiographic assessment of LA size and function in horses.
Abstract
Objective—To compare Doppler echocardiographic variables of left ventricular (LV) function with those obtained invasively via cardiac catheterization under a range of hemodynamic conditions.
Animals—7 healthy anesthetized cats (1 to 3 years of age).
Procedure—Cats were anesthetized and instrumented
to measure the time constant of isovolumic
relaxation (tau [
]), LV end-diastolic pressure
(LVEDP), peak negative and positive rate of change
of LV pressure, arterial blood pressure, and cardiac
output. Echocardiographic variables of diastolic function
(isovolumic relaxation time [IVRT], early LV flow
propagation velocity [Vp], transmitral and pulmonary
venous flow velocity indices, and LV tissue Doppler
imaging indices) were measured simultaneously
over a range of hemodynamic states induced by
treatments with esmolol, dobutamine, cilobradine,
and volume loading. Correlation between invasive
and noninvasive measures of LV filling was determined
by univariate and multivariate regression
analyses.
Results—Significant correlations were found
between and IVRT, peak Vp, peak late transmitral
flow velocity, and peak systolic pulmonary venous
flow velocity. A significant correlation was found
between LVEDP and early diastolic transmitral flow
velocity (peak E) and the ratio of peak E to peak Vp,
but not between LVEDP and peak Vp.
Conclusion and Clinical Relevance—IVRT and Vp can be used as noninvasive indices of LV relaxation; Vp was independent of preload and heart rate in this study. The E:Vp ratio may be useful as an indicator of LV filling pressure. (Am J Vet Res 2003;64:93–103)
Abstract
Objective—To determine whether serum concentrations of cardiac troponin I (cTnI) and cardiac troponin T (cTnT) are increased in dogs with gastric dilatationvolvulus (GDV) and whether concentrations correlate with severity of ECG abnormalities or outcome.
Design—Prospective case series.
Animals—85 dogs with GDV.
Procedure—Serum cTnI and cTnT concentrations were measured 12 to 24, 48, 72, and 96 hours after surgery. Dogs were grouped on the basis of severity of ECG abnormalities and outcome.
Results—cTnI and cTnT were detected in serum from 74 (87%) and 43 (51%) dogs, respectively. Concentrations were significantly different among groups when dogs were grouped on the basis of severity of ECG abnormalities (none or mild vs moderate vs severe). Dogs that died (n = 16) had significantly higher serum cTnI (24.9 ng/ml) and cTnT (0.18 ng/ml) concentrations than did dogs that survived (2.05 and < 0.01 ng/ml, respectively). Myocardial cell injury was confirmed at necropsy in 4 dogs with high serum cardiac troponin concentrations.
Conclusions and Clinical Relevance—Results indicate that concentrations of cTnI and cTnT suggestive of myocardial cell injury can commonly be found in serum from dogs with GDV and that serum cardiac troponin concentrations are associated with severity of ECG abnormalities and outcome. (J Am Vet Med Assoc 2002;221:381–388)
Abstract
Objective—To evaluate the accuracy of a commercial ultrasonographic cardiac output (CO) monitoring system (UCOMS) in anesthetized Beagles as assessed by comparison with thermodilution CO (TDCO).
Animals—8 healthy anesthetized Beagles.
Procedures—Simultaneous UCOMS and TDCO measurements of CO were obtained during 4 hemodynamic states: baseline anesthesia (0.5% to 1.5% isoflurane), a higher depth of anesthesia (2% to 3.5% isoflurane) to yield a ≥ 15% reduction in systolic arterial blood pressure, IV infusion of colloidal solution to a mean right atrial pressure of ≥ 15 mm Hg, and IV infusion of dobutamine at 5 μg/kg/min. Measurements were obtained at 2 probe positions: the subxiphoid region and the right thoracic inlet. Correlation and agreement of results between methods were determined via linear regression analysis and Bland-Altman plots.
Results—A significant positive correlation was detected between UCOMS andTDCO measurements obtained at the subxiphoid (R = 0.86) and thoracic inlet (R = 0.83) positions. Bland-Altman plots revealed minimal bias between methods (bias ± SD, −0.03 ± 0.73 L/min and −0.20 ± 0.80 L/min for subxiphoid and thoracic inlet measurements, respectively). However, the percentage error associated with UCOMS measurements made at the 2 positions was > 45%.
Conclusions and Clinical Relevance—When compared with the results of TDCO, CO measured with the UCOMS exceeded commonly accepted limits of error in healthy dogs. The UCOMS was, however, able to track changes in CO across hemodynamic states. Additional research is needed to assess the usefulness of the UCOMS for monitoring CO in critically ill dogs.
Abstract
Objective—To identify Doppler echocardiographic (DE) variables that correlate with left ventricular filling pressure (LVFP).
Animals—7 healthy dogs (1 to 3 years old).
Procedures—Dogs were anesthetized and instrumented to measure left atrial pressure (LAP), left ventricular pressures, and cardiac output. Nine DE variables of LVFP derived from diastolic time intervals, transmitral and pulmonary venous flow, and tissue Doppler images were measured over a range of hemodynamic states induced by volume loading and right atrial pacing. Associations between simultaneous invasive measures of LVFP and DE measures of LVFP were determined by use of regression analysis. Receiver operating characteristic analysis was used to predict increases in mean LAP on the basis of DE variables.
Results—Mean LAP was correlated with several DE variables: the ratio between peak velocity during early diastolic transmitral flow and left ventricular isovolumic relaxation time (peak E:IVRT) during sinus rhythm and during right atrial pacing, IVRT, the ratio between late diastolic transmitral flow velocity and pulmonary venous flow duration, and the interval between onset of early diastolic mitral annulus motion and onset of early diastolic transmitral flow. Cutoff values of 2.20 and 2.17, for peak E:IVRT in dogs with sinus rhythm and atrial pacing predicted increases in mean LAP (≥ 15 mm Hg) with sensitivities of 90% and 100% and specificities of 92% and 100%, respectively.
Conclusions and Clinical Relevance—Doppler echocardiography can be used to predict an increase in LVFP in healthy anesthetized dogs subjected to volume loading.
Abstract
Objective—To evaluate the effects of the pacemaker funny current (If) inhibitor ivabradine on heart rate (HR), left ventricular (LV) systolic and diastolic function, and left atrial performance in healthy cats and cats with hypertrophic cardiomyopathy (HCM).
Animals—6 healthy cats and 6 cats with subclinical HCM.
Procedures—Anesthetized cats underwent cardiac catheterization and were studied over a range of hemodynamic states induced by treatment with esmolol (200 to 400 μg/kg/min, IV), esmolol and dobutamine (5 μg/kg/min, IV), ivabradine (0.3 mg/kg, IV), and ivabradine and dobutamine. Left ventricular systolic and diastolic function, cardiac output, and left atrial function were studied via catheter-based methods and echocardiography.
Results—Treatment with ivabradine resulted in a significant reduction of HR, rate-pressure product, and LV contractile function and a significant increase in LV end-diastolic pressure, LV end-diastolic wall stress, and LV relaxation time constant (tau) in cats with HCM. Concurrent administration of ivabradine and dobutamine resulted in a significant increase of LV contractility and lusitropy, with blunted chronotropic effects of the catecholamine. Left atrial performance was not significantly altered by ivabradine in cats with HCM. Regression analysis revealed an association between maximum rate of LV pressure rise and tau in cats with HCM.
Conclusions and Clinical Relevance—Ivabradine had significant effects on several cardiovascular variables in anesthetized cats with HCM. Studies in awake cats with HCM are needed to clinically validate these findings.
