Comparison of the myocardial performance index derived by use of pulsed Doppler echocardiography and tissue Doppler imaging in dogs with volume overload

Reference Values and Repeatability of Pulsed Wave Doppler Echocardiography Parameters in Normal Donkeys

Simple Summary

Cardiovascular disease is underreported in donkeys, possibly related to their limited athletic posture and frequent poor performance-related examinations. Reports on treatments for cardiovascular disease are anecdotal in donkey. Normal echocardiographic parameters have been reported in healthy donkeys. The aim of the present study was to establish the reference values and repeatability for Pulsed Wave Doppler echocardiographic variables of the mitral valve, aortic valve and myocardial performance. Two-dimensional Color flow mapping and spectral Doppler modes were performed. For the mitral valve, the mean velocity, pressure gradient and duration of E-wave were 57.7 ± 12.5 cm/s, 1.4 ± 0.7 mmHg and 0.4 ± 0.13 s, respectively. The results of the present study provide the reference values of PW echocardiographic parameters measurements in normal adult donkeys. Such reference values are helpful, especially when confronted with clinical cases with cardiovascular disorders.

Abstract

In the present study, thirty clinically healthy donkeys were used to establish the reference values and repeatability for Pulsed Wave Doppler echocardiographic variables of the mitral valve, aortic valve and myocardial performance. 2-dimensional Color flow mapping and spectral Doppler modes were performed. For the mitral valve, the mean velocity, pressure gradient and duration of E-wave were 57.7 ± 12.5 cm/s, 1.4 ± 0.7 mmHg and 0.4 ± 0.13 s, respectively. The velocity, pressure gradient and duration of the A-wave were 32.3 ± 9.1 cm/s, 0.3 ± 0.04 mmHg and 0.3 ± 0.1 s, respectively. The mitral valve area, pressure half time, pulsatility index (PI), resistance index (RI) and velocity time integral (VTI) were 1.8 ± 0.5 cm², 66 ± 17 ms, 2.8 ± 1.4, 0.9 ± 0.03 and 19.1 ± 5.7 cm, respectively. For the aortic valve, the mean velocity was 64.9 ± 10.4 cm/s, pressure gradient was 1.8 ± 0.4 mmHg, pulsatility index was 1.4 ± 0.3, resistance index was 0.9 ± 0.02, VTI was 25.02 ± 6.2 cm, systolic/diastolic was 19 ± 4.7 and heart rate was 95.7 ± 28.9 per minute. For Myocardial Performance Index (LV)–Tei Index, the mean ejection, isovolumic relaxation, isovolumic contraction time and myocardial performance index were 0.24 ± 0.01, 0.14 ± 0.01, 0.14 ± 0.02 and 1.2 ± 0.1 s, respectively. The results of the present study provide the reference values of PW echocardiographic parameter measurements in normal adult donkeys. Such reference values are helpful, especially when confronted with clinical cases with cardiovascular disorders.

Evaluation of Right Ventricular Function and Dyssynchrony in a Dog Model of Acute Pulmonary Embolism: Diagnostic Utility and Reversibility

Background

The diagnosis of acute pulmonary thromboembolism is challenging in dogs. Little has been reported on changes in echocardiographic indices in dogs with acute pulmonary thromboembolism. The objective of this study was to validate the relationship between echocardiographic indices and right heart catheterization variables in dogs with acute pulmonary embolism and to identify a useful echocardiographic index for diagnosing acute pulmonary embolism.

Materials and Methods

Six healthy laboratory beagles were included in the study. Echocardiography and right heart catheterization were performed in a dog model of acute pulmonary embolism produced by microsphere injection. Echocardiographic indices, including the right ventricular (RV) Tei index, RV longitudinal strain, and the dyssynchrony index using speckle tracking echocardiography, transmitral flow, and eccentricity index, were measured.

Results

The mean pulmonary arterial pressure increased (22.2 ± 1.2 mmHg) and the blood pressure decreased after microsphere injection. Although the mean pulmonary arterial pressure remained elevated, the blood pressure recovered 2 days after the microsphere injection. Most echocardiographic indices of RV function were significantly impaired following microsphere injection and recovered after 2 days. In contrast, the RV Tei index was significantly impaired after microsphere injection and the impairment persisted after 2 days. Multivariable analysis revealed that the RV Tei index was an independent echocardiographic predictor of pulmonary vascular resistance (β = 0.88, P < 0.001), and transmitral early diastolic wave was an independent predictor of the cardiac index (β = −0.86, P = 0.001).

Conclusions

The RV Tei index is a useful echocardiographic index for diagnosing acute pulmonary embolism. Ventricular interdependence may be an important factor causing low cardiac output in dogs with acute pulmonary embolism.

Novel Approach to Assess Cardiac Function Using Systolic Performance and Myocardial Performance Indices From Simultaneous Electrocardiography and Phonocardiography Recordings in Dogs With Various Stages of Myxomatous Mitral Valve Disease

Background and Objective: Myxomatous mitral valve disease (MMVD) progression entails changes in the structural and functional properties of the heart affecting cardiac timings and intervals within the cardiac cycle. Conventionally, echocardiography is used to determine the cardiac time intervals (CTIs) including systolic and myocardial performance indices (SPI and MPI) in evaluating cardiac function. Alternatively, these CTIs can also be measured using simultaneous recordings of electrocardiography (ECG) and phonocardiography (PCG), but their values in different MMVD stages remain to be established. This study aimed to establish and prove the use of derived SPI and MPI from a dedicated device as a novel approach to assess cardiac function in different stages of MMVD dogs. Materials and Methods: A prospective study in 52 dogs with different MMVD stages measured the CTIs using a novel device. These were compared and correlated with standard echocardiographic parameters. The predictive value of SPI and three new proposed formulas to estimate MPI (i.e., F1, F2, and F3) in association with asymptomatic from symptomatic MMVD dogs were investigated. Results: Our findings revealed that CTI parameters measured from a novel device including QS1, QS2, S1S2, MPI-F1, and MPI-F2 were altered at different stages of MMVD. The SPI and all proposed MPI formulas were comparable with the systolic time interval and Tei index from echocardiography. In addition, the SPI, MPI-F1, and MPI-F2 were significantly correlated with the Tei index. However, the SPI was not able to differentiate the various stages of MMVD. Conversely, only the MPI-F1 (i.e., (QS1 + S2)/S1S2) demonstrated good predictive accuracy when compared between asymptomatic and symptomatic MMVD dogs similar to the Tei index. Moreover, this formula was able to differentiate stages B1 and C with remarkable predictive accuracy, higher sensitivity, and high specificity when compared with the Tei index. Conclusion: We have successfully described the CTI parameters in different MMVD stages using simultaneous ECG and PCG recordings in dogs. Furthermore, we have proven that the concept of using the newly proposed parameters from a novel device is equivalent to the Tei index. Thus, we established a novel approach to evaluate cardiac function and its supportive use in the diagnosis of MMVD patients.

Effects of intravenous administration of pimobendan on hemodynamic indices and indices of left atrial longitudinal strain derived from speckle-tracking echocardiography in healthy dogs

OBJECTIVE

To determine the effects of IV administration of pimobendan on hemodynamic indices and indices of left atrial (LA) longitudinal strain by speckle-tracking echocardiography in healthy dogs.

ANIMALS

6 healthy Beagles.

PROCEDURES

After the dogs were anesthetized, the right heart was catheterized and 2-D conventional and speckle-tracking echocardiography were performed before and after IV administration of 0.15 mg of pimobendan/kg. Speckle-tracking echocardiography was performed to assess the 3 LA phasic functions through LA deformation (longitudinal strain and strain rate) and volumetric analyses.

RESULTS

Pimobendan significantly increased stroke volume and cardiac output and decreased systemic vascular resistance. Pimobendan significantly improved left ventricular function assessed by the Tei index and LA booster pump function assessed by LA longitudinal strain and change in fractional volume during atrial systole. Indices of LA reservoir and conduit function were unchanged.

CONCLUSIONS AND CLINICAL RELEVANCE

In healthy dogs, IV administration of pimobendan improved the indices of LA booster pump function but had no effect on the indices of LA reservoir and conduit functions. Further studies are needed to validate whether these results can be extrapolated to dogs with myxomatous mitral valve disease.

Effect of acute volume loading on left atrial strain values derived from two-dimensional speckle tracking echocardiography in dogs

The purpose of this study was to evaluate the cardiac acute volume loading effect on left atrial (LA) strain and strain rate (SR) parameters derived from two-dimensional speckle tracking echocardiography (2D-STE) in healthy dogs. Six healthy beagles were anesthetized and subjected to increase cardiac preload by intravenous infusion with lactated Ringer solution at 150 ml/kg/hr for 90 min. A Swan-Ganz catheter was placed to directly measure the mean pulmonary capillary wedge pressure (PCWP). Echocardiography was performed before (baseline) and at 15, 30, 45, 60, 75, and 90 min after acute volume loading began. Apical 4-chamber images focused on the LA were digitally recorded for later strain and SR analysis via 2D-STE. Acute volume loading significantly increased from baseline during LA strain and SR as assessed by the speckle tracking–based technique during reservoir and conduit function at 15 to 90 min after volume load began, and strain indices representing booster pump function were enhanced at 45 to 90 min. In addition, acute volume loading resulted in a significantly greater PCWP after fluid infusion. On multiple regression analysis, quadratic regression analysis was a better fit for the relationship between PCWP and all LA functional indices. Our findings indicated that LA function analyzed by strain and SR was enhanced during cardiac acute volume loading in healthy dogs. The change in strain and SR during acute volume loading should be interpreted with caution during the diagnosis of heart diseases related to volume overload.

Left ventricular vortex and intraventricular pressure difference in dogs under various loading conditions

Restrictions on the conventional evaluation of diastolic function have been recognized, especially under various loading conditions. Recently, new noninvasive ventricular vortex indexes have been introduced and are expected to reflect the cardiac function. Physiologically, there is a hypothesis that the intraventricular pressure difference (IVPD) is related to the formation of vortexes. IVPD and vortex indexes were simultaneously measured, and the relationship between the two was investigated. To verify the possibility of diastolic vorticity as an index of diastolic relaxation, a correlation between diastolic vorticity and the load dependency of vorticity [time constant (τ)] was examined. Six healthy dogs were studied using transthoracic echocardiography, pressure, and a conductance catheter. Vorticity was analyzed using vector flow mapping (VFM). IVPD was determined using Euler's equation with color M-mode Doppler images. Data were obtained at baseline, at balloon dilatation in the thoracic aorta to alter afterload, at hydroxyethyl starch infusion to alter preload, and at milrinone administration to alter ventricular relaxation. Peak vorticity at early diastole (E-Vor) and IVPD of the midventricle (MIVPD) decreased under pressure loading, were unchanged under volume loading, and increased during milrinone administration. In multivariate analysis, the independent predictors of τ were global longitudinal strain, strain rate at early diastole, and E-Vor. MIVPD was strongly correlated with E-Vor ( r = 0.84). VFM-derived peak E vorticity was strongly related to IVPD, especially MIVPD, under various loading conditions. Both of these novel indexes are promising as reliable indexes of ventricular relaxation, independent from preload. NEW & NOTEWORTHY We showed the close relationship of vortex and intraventricular pressure difference and showed that both of them can become new markers of the left ventricular relaxation property. Our present study creates a paradigm for future studies in the field of intraventircular flow physiology and clinical diastology.

Effects of experimental cardiac volume loading on left atrial phasic function in healthy dogs

OBJECTIVE To elucidate the relationship between acute volume overload and left atrial phasic function in healthy dogs. ANIMALS 6 healthy Beagles. PROCEDURES Dogs were anesthetized. A Swan-Ganz catheter was placed to measure mean pulmonary capillary wedge pressure (PCWP). Cardiac preload was increased by IV infusion with lactated Ringer solution at 150 mL/kg/h for 90 minutes. Transthoracic echocardiography was performed before (baseline) and at 15, 30, 45, 60, 75, and 90 minutes after volume loading began. At each echocardiographic assessment point, apical 4-chamber images were recorded and analyzed to derive time-left atrial area curves. Left atrial total (for reservoir function), passive (for conduit function), and active (for booster-pump function) fractional area changes were calculated from the curves. RESULTS Volume overload resulted in a significant increase from baseline in PCWP from 15 to 90 minutes after volume loading began. All fractional area changes at 15 to 90 minutes were significantly increased from baseline. In multiple regression analysis, quadratic regression models were better fitted to the relationships between PCWP and each of the total and active fractional area changes than were linear regression models. A linear regression model was better fitted to the relationship between PCWP and passive fractional area change. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that left atrial phasic function assessed on the basis of left atrial phasic areas was enhanced during experimental cardiac volume loading in healthy dogs. The effect of volume load should be considered when evaluating left atrial phasic function by indices derived from left atrial phasic sizes.

Prospective evaluation of Doppler echocardiography, tissue Doppler imaging and biomarkers measurement for the detection of doxorubicin-induced cardiotoxicity in dogs: A pilot study

The purpose of this pilot study was to evaluate the usefulness of selected echocardiographic parameters, NT-proBNP and cardiac troponin I (cTnI) in the detection of cardiotoxicity in dogs treated with doxorubicin for various malignancies. Echocardiographic studies and biomarker measurements were performed before each administration of doxorubicin, then 1 and 3 months after completion of therapy. Thirteen dogs were included, with a total cumulative dose of doxorubicin ranging from 30 to 150 mg/m(2). E/A ratio significantly decreased during doxorubicin administration (p=0.047). cTnI level was also significantly affected by treatment (p=0.046), increasing above normal at least at one time point in 11 of 13 dogs. The results of this pilot study suggest that monitoring of left ventricular diastolic function and cTnI level measurement might be useful in the early detection of cardiotoxic signs of doxorubicin therapy in dogs.

The relationship between invasive hemodynamic measurements and tissue Doppler-derived myocardial velocity and acceleration during isovolumic relaxation in healthy dogs

This study investigated the feasibility of using the values of tissue Doppler imaging (TDI)-derived myocardial velocity during isovolumic relaxation (V(IR)) and myocardial acceleration during isovolumic relaxation (ACC) obtained from the left ventricular (LV) free wall to evaluate LV relaxation in normal dogs. Seven dogs were anesthetized, and dobutamine or esmolol was infused at a rate of 5.0 and 10.0 mug/kg/min or 100 and 500 mug/kg/min, respectively, via a cephalic vein. The order of drug administration (dobutamine or esmolol) was assigned to each dog. Simultaneous pulsed-Doppler (PD) echocardiography, TDI and hemodynamic measurements were performed. Compared with the baseline values, dobutamine significantly increased dP/dt min, but significantly shortened tau (tau). Similarly, esmolol significantly decreased dP/dt min, but significantly prolonged tau. Compared with the baseline values, dobutamine significantly increased V(IR) and ACC, and esmolol significantly decreased V(IR) and ACC. Both dP/dt min and tau were significantly correlated with TDI-derived IVRT (r=-0.43 and 0.74), V(IR) (r=0.85 and -0.49) and ACC (r=0.84 and -0.52). These results indicate that the TDI-derived V(IR) and ACC values obtained from the LV free wall can potentially be used to assess LV relaxation in dogs.

Methods and reliability of tissue Doppler imaging for assessment of left ventricular radial wall motion in horses

BACKGROUND

Noninvasive assessment of left ventricular (LV) function is incompletely studied in horses.

OBJECTIVES

The goals of this study were to investigate the feasibility, techniques, and reliability of tissue Doppler imaging (TDI) for characterization of LV radial wall motion in healthy horses.

ANIMALS

Three Standardbreds, 3 Thoroughbreds; age 8-14 years; body weight 517-606 kg.

METHODS

Repeated echocardiographic examinations were performed by 2 observers in unsedated horses using TDI. Test reliability was determined by estimating measurement variability, within-day interobserver variability, and between-day interobserver and intraobserver variability of all echocardiographic variables. Variability was expressed as coefficient of variation (CV) and the absolute value below which the difference between 2 measurements will lie with 95% probability.

RESULTS

Assessment of LV radial wall motion by TDI was feasible in all horses. Measurement variabilities were very low (CV < 5%) to low (CV 5-15%) for most variables. Within-day interobserver variability as well as between-day interobserver and intraobserver variabilities were low to moderate (CV 16-25%) for most variables. All pulsed-wave TDI variables of systolic LV function showed very low to low variability, whereas some of the variables of LV diastolic and LA function showed moderate to high (CV > 25%) variability. Pulsed-wave TDI variables appeared more reliable than color TDI variables.

CONCLUSIONS AND CLINICAL IMPORTANCE

Measurement of TDI indices of LV function is feasible and reliable in adult Standardbred and Thoroughbred horses. The clinical relevance of LV function assessment by TDI remains to be determined.

Impact of intravenous immunoglobulin infusion on longitudinal left ventricular performance in patients with acute Kawasaki disease of usual course

PURPOSE

To determine the acute change in cardiac performance after intravenous immunoglobulin infusion (IVIG) in patients with acute Kawasaki disease (KD).

MATERIALS AND METHODS

Subjects were 33 patients with KD who were treated with IVIG 2 g/kg and recovered without coronary artery lesion and 27 controls. Subjects underwent combined two-dimensional, Doppler, and tissue Doppler echocardiographic (TDI) studies. In KD, these echocardiographic studies were performed before IVIG, 48 h after IVIG, and in convalescence. Echocardiographic variables were compared between KD and controls as well as among 3 time points in KD.

RESULTS

Before IVIG, KD showed significantly higher peak aortic velocity and shorter aortic ejection time as results of tachycardia and significantly lower E' (p<0.04) but significantly higher E/E' (p<0.02). After IVIG, patients with KD became afebrile and showed significantly lower TDI indices such as S', E', and, A' and isovolumic acceleration (IVA) (163+/-56 vs. 208+/-70 cm/s(2), p<0.01) with higher TDI-derived Tei index (0.50+/-0.10 vs. 0.44+/-0.06, p<0.02) than controls. These differences tended to disappear in convalescence. In analysis of repeated measurements, except for hemodynamic changes associated with tachycardia, S' (7.9+/-1.3 vs. 7.0+/-1.1 vs. 7.4+/-0.9 cm/s, p<0.001), IVA (227+/-72 vs. 163+/-56 vs. 180+/-63, p<0.05), and A' (7.7+/-3.0 vs. 5.6+/-1.3 vs. 6.7+/-2.3 cm/s, p<0.001) were significantly different among these time points.

CONCLUSIONS

In patients with acute KD with usual course, IVIG induced transient sub-clinical longitudinal left ventricular dysfunction.

Is the aging heart similar to the diabetic heart? Evaluation of LV function of the aging heart with Tissue Doppler Imaging

BACKGROUND AND AIMS

Left ventricular (LV) function in the healthy aging heart is modified by biochemical changes with advancing age. We employed for the first time Tissue Doppler Imaging (TDI), to identify which phase of the cardiac cycle is involved.

METHODS

TDI was performed in 175 aging subjects, free of cardiovascular and/or respiratory disease (group II), and in 182 healthy adults enrolled as the control group (group I), to calculate the Myocardial Performance Index (MPI). The index derives from the values of Isovolumetric Contraction Time (ICT), Isovolumetric Relaxation Time (IRT) and Left Ventricular Ejection Time (LVET) measured in ms, according to the formula: (ICT+IRT)/LVET.

RESULTS

An increase in MPI in group II was shown, with significant lengthening of IRT in comparison with the same value obtained in the control group (group I), ICT and LVET were unchanged.

CONCLUSIONS

The rise in IRT in the aging healthy heart is dependent on diastolic LV dysfunction consequent upon the formation of Advanced Glycosilation End-product (AGE) crosslinks with connectival proteins of interstitial myocardial tissue. Agerelated increase in oxidative stress also modifies some interstitial compounds, favoring hardening of ventricular walls. These changes are similar to those happening in the diabetic heart, and TDI seems to be able to define non-invasively which phase of the cardiac cycle is impaired.