Echocardiography In Rats Research Articles

Comparative assessment of coronary physiology using transthoracic pulsed-wave Doppler and myocardial contrast echocardiography in rats

BackgroundCoronary physiology assessment in rodents by ultrasound is an excellent noninvasive and easy to perform technique, including pulsed-wave Doppler (PWD) and myocardial contrast echocardiography (MCE). Both techniques and the corresponding calculated parameters were investigated in this study at rest as well as their response to pharmacologically induced stress.MethodsLeft ventricular myocardial function was assessed in eight anaesthetised rats using transthoracic echocardiography. Coronary physiology was assessed by both PWD of the left coronary artery and MCE using a bolus method. Measurements were performed at rest and under stimulation with adenosine and dobutamine. Effects of stimulation on the calculated parameters were evaluated and rated by effect size (η2).ResultsChanges could be demonstrated by selected parameters of PWD and MCE. The clearest effect in PWD was found for diastolic peak velocity (η2 = 0.58). It increased from 528 ± 110 mm/s (mean ± standard deviation) at rest to 839 ± 342 mm/s (p = 0.001) with adenosine and 1093 ± 302 mm/s with dobutamine (p = 0.001). The most distinct effect from MCE was found for the normalised wash-in rate (η2 = 0.58). It increased from 1.95 ± 0.35% at rest to 3.87 ± 0.85% with adenosine (p = 0.001) and 3.72 ± 1.03% with dobutamine (p = 0.001).ConclusionInduced changes in coronary physiology by adenosine and dobutamine could successfully be monitored using MCE and PWD in anaesthetised rats. Due to the low invasiveness of the measurements, this protocol could be used for longitudinal animal studies.

Early and dynamic detection of doxorubicin induced cardiotoxicity by myocardial contrast echocardiography combined with two-dimensional speckle tracking echocardiography in rats.

Anthracycline-induced cardiotoxicity is well-known as a side effect of chemotherapy. Currently, clinical imaging techniques are not capable to detect doxorubicin (DOX)-induced cardiotoxicity before a functional decline. The purpose of this study was to evaluate whether myocardial contrast echocardiography (MCE) can dynamically monitor the cardiac changes in the early stage in the DOX-induced rat model of cardiotoxicity. A weekly injection of 2.5 mg/kg of DOX was used to generate a rat model of cardiotoxicity. All groups underwent ultrasonic examinations including standard echocardiography, 2D speckle tracking echocardiography (2D-STE), and MCE. Then all rats were sacrificed immediately for histopathological evaluation. A total of eight control rats and 32 DOX-treated rats were included in the study and grouped according to their treatment period. Decreased quantitative parameters of myocardial blood flow (MBF) (control vs. group 1: 133.31 ± 20.23 dB/s vs. 103.35 ± 21.60 dB/s, P = 0.048) and β (control vs. group 2: 11.17 ± 1.48/s vs. 7.15 ± 1.23/s, P < 0.001) were observed after 2 and 4 weeks of treatment, respectively, while left ventricular global strain (control vs. group 3: -23.67 ± 3.92% vs. -16.01 ± 3.40%, P = 0.002) decreased after 6 weeks of treatment and left ventricular ejection fraction (LVEF) (control vs. group 4: 82.41 ± 3.20% vs. 70.89 ± 9.30%, P = 0.008) decreased after 8 weeks of treatment. The main histopathological features are increased myocardial vacuolization and interstitial fibrosis and decreased myocardial microvessel density. Compared with standard echocardiography and 2D-STE, MCE can accurately and non-invasively detect changes in early myocardial perfusion, demonstrating the clinical potential of continuous and dynamic monitoring of DOX-induced cardiotoxicity.

Effect of Loading Changes on the Intraventricular Pressure Measured by Color M-Mode Echocardiography in Rats.

Evaluation of diastolic function is a pivotal challenge due to limitations of the conventional echocardiography, especially when the heart rate is rapid as in rats. Currently, by using color M-mode echocardiography (CMME), intraventricular pressure difference (IVPD) and intraventricular pressure gradient (IVPG) in early diastole can be generated and are available as echocardiographic indices. These indices are expected to be useful for the early diagnosis of heart failure (HF), especially diastolic dysfunction. There have not been any studies demonstrating changes in IVPD and IVPG in response to changes in loading conditions in rats. Therefore, the present study aims to evaluate CMME-derived IVPD and IVPG changes in rats under various loading conditions. Twenty rats were included, divided into two groups for two different experiments, and underwent jugular vein catheterization under inhalational anesthetics. Conventional echocardiography, CMME, and 2D speckle tracking echocardiography were measured at the baseline (BL), after intravenous infusion of milrinone (MIL, n = 10), and after the infusion of hydroxyethyl starch (HES, n = 10). Left ventricular IVPD and IVPG were calculated from color M-mode images and categorized into total, basal, mid-to-apical, mid, and apical parts, and the percentage of the corresponding part was calculated. In comparison to the BL, the ejection fraction, mid-to-apical IVPG, mid IVPG, and apical IVPD were significantly increased after MIL administration (p < 0.05); meanwhile, the end-diastolic volume, E-wave velocity, total IVPD, and basal IVPD were significantly increased with the administration of HES (p < 0.05). The increase in mid-to-apical IVPD, mid IVPD, and apical IVPD indicated increased relaxation. A significant increase in basal IVPD reflected volume overloading by HES. CMME-derived IVPD and IVPG are useful tools for the evaluation of various loading conditions in rats. The approach used in this study provides a model for continuous data acquisition in chronic cardiac disease models without drug testing.

The Prominin-1-Derived Peptide Improves Cardiac Function Following Ischemia.

Myocardial infarction (MI) remains the leading cause of death in the western world. Despite advancements in interventional revascularization technologies, many patients are not candidates for them due to comorbidities or lack of local resources. Non-invasive approaches to accelerate revascularization within ischemic tissues through angiogenesis by providing Vascular Endothelial Growth Factor (VEGF) in protein or gene form has been effective in animal models but not in humans likely due to its short half-life and systemic toxicity. Here, we tested the hypothesis that PR1P, a small VEGF binding peptide that we developed, which stabilizes and upregulates endogenous VEGF, could be used to improve outcome from MI in rodents. To test this hypothesis, we induced MI in mice and rats via left coronary artery ligation and then treated animals with every other day intraperitoneal PR1P or scrambled peptide for 14 days. Hemodynamic monitoring and echocardiography in mice and echocardiography in rats at 14 days showed PR1P significantly improved multiple functional markers of heart function, including stroke volume and cardiac output. Furthermore, molecular biology and histological analyses of tissue samples showed that systemic PR1P targeted, stabilized and upregulated endogenous VEGF within ischemic myocardium. We conclude that PR1P is a potential non-invasive candidate therapeutic for MI.

Ultrasound assessment of heart remodelling affected by therapeutic hypothermia and MSC on myocardial infarction model

Background. Late seeking medical advice, limited number of cardiac surgery hospitals and conservative treatment, which does not seem to be always efficacious, trigger the search for new, more effective mode therapy of acute myocardial infarction (MI). Recently, mesenchymal stromal cells (MSCs) have come into sharp focus of scientists due to the prospects for clinical use. On the other hand, multicenter studies have proved that therapeutic hypothermia (TH) has neuro- and cardioprotective effects, and it is administered as one of the urgent methods in providing primary health care.&#x0D; Purpose. Providing and analyzing ultrasonography (US) of rat hearts with experimental MI in order to determine the nature of heart remodelling under combined use of TH and introducing allogeneic MSCs.&#x0D; Materials and methods. The study involved 90 outbred white rats weighing 240–270 g. Myocardial infarction was reproduced by ligating the descending branch of the left coronary artery on the border of the upper and middle third of the vessel. Therapeutic hypothermia was performed in a cold chamber, 60 minutes long. The local skin temperature of the neck area was maintained at +4 оC, while the rectal and tympanic temperature decreased to + 25 оC. A suspension of allogeneic cryopreserved MSCs of the placenta with a concentration of 1.2 × × 106 cells/ml was administered once intravenously through v. saphena magna. Heart sonography was carried out by means of «Сономед 500» («СПЕКТРОМЕД», Russia) ultrasound scanner in B- and M-mode using a linear sensor 7.5L38 with frequency of 7.5 MHz.&#x0D; Results and discussion. The control group with experimental MI showed significantly suppressed function of the left ventricle (LV). It resulted in decreasing stroke volume (SV) and cardiac output (CO) and on the whole indicated reduced ejection fraction (EF) to 46.04 %, that was 35 % less than the corresponding normal range. According to the values of relative wall thickness (RWT) and left ventricular mass (LVM) on day 7 and day 30 after ligating the left coronary artery, LV remodelling was proceeding via eccentric mode of LV alteration. Therapeutic hypothermia was not able to completely stop the pathophysiological processes associated with coronary ligation. EF was not significantly different from the control group, and was 51.08 ± ± 2.68 %. On day 7 of the experiment, heart remodelling in this group was proceeding according to the normal geometry model, and on day 30 – according to the eccentric model. In spite of the volume overload causing post-infarction extension of the left ventricular cavity, in the group with applying MSCs, on day 7 there was a compensatory increase of the stroke volume, 1.8 times over compared to the group with normal range values and 2.3 over compared to the control group. The ejection fraction was 17 % less than the normal range, but statistically significantly higher than the corresponding indicator of the control group of this observation period. Heart remodelling after applying allogeneic MSCs associated with MI at all stages of observation was proceeding by eccentric LV hypertrophy. Аfter therapeutic hypothermia and applying MSCs associated with experimental myocardial infarction on day 7 and day 30, the group recorded the best values of echo params of LV anatomical structures, indicating no dilatation along with occuring moderate myocardial hypertrophy. The ejection fraction showed the best outcome, i. e. 58.78 %, while LV remodelling was minimal, occurring according to normal heart geometry.&#x0D; Conclusions. Applying echocardiography in rats is a very informative diagnosis method which makes it possible to describe the type of structural and functional remodelling of the myocardium associated infarction at early and late observation stages. The ultrasound study showed that the closest to the normal range was the group of animals exposed to therapeutic hypothermia and MSC transplantation. According to LVM and RWT values, in the rats of that group on day 7 and day 30 of the experiment, LV remodelling was characterized by normal geometry.

Early Intervention of Tongxinluo () on Right Ventricular Function Assessed by Echocardiography in Rats with Pulmonary Arterial Hypertension Induced by Monocrotaline.

To investigate the effect of early intervention of Tongxinluo (, TXL) on right ventricular function (RVF) of rats with pulmonary arterial hypertension (PAH) induced by monocrotaline (MCT). A total of 30 adult male Sprague-Dawley rats were assigned to 5 groups with complete random experiment design: Sham group (Sham), MCT group, TXL group, sildenafil (SIL) group and combination group (TXL+SIL), 6 rats in each group. Rats were injected with 50 mg/kg MCT solution for inducing PAH model except for those in the sham group. From the day of modeling, rats of TXL, SIL and TXL+SIL groups were given TXL (1.2 g/kg), SIL (10 mg/kg) and combination solution (TXL:1.2 g/kg, SIL: 10 mg/kg) respectively, and rats in Sham and MCT groups were given normal saline (5 mL/kg). The samples were collected and tested after 21 consecutive days of intragastric administration. Echocardiography was used to measure the related indices of RVF, including pulmonary arterial flow spectrum, pulmonary artery diameter (PAD), right ventricular wall thickness (RVWT), right ventricular diameter (RVD), tricuspidannular plane systolic excursion (TAPSE), right atrium transverse diameter (RAT), and inferior vena cava diameter (IVCD). Elastic Verhoeff-Van Gieson staining was adopted to measure the percentage of wall thickness (WT%) of pulmonary arteriols. Hematoxylin-eosin staining was used to measure the cross-sectional area (CSA) of right ventricular cardiomyocytes. MCT-induced PAH rat model was successfully established. In MCT group the wall of pulmonary arterioles exhibited a prominent-increase thickness, PAD, RVWT, RVD, RAT, IVCD, WT%, right ventricular hypertrophy index (RVHI) as well as CSA of RV cardiomyocyte significantly increased (all P<0.01), and TAPSE markedly decreased (P<0.01). At the same time, TXL prominently improved all of the above indices (all P<0.01). In comparison with SIL, TXL significantly reduced RVD (P<0.05) and decreased CAS of RV cardiomyocytes (P<0.01), but TAPSE in SIL group was much larger than in TXL group (P<0.01). Moreover, TAPSE in TXL+SIL group was larger than that in TXL group (P<0.01), while the two groups performed equally well in terms of the other indices. Early intervention of TXL could inhibit pulmonary arterioles remodeling, and improve RVF by attenuating right ventricular hypertrophy, and TXL has a stronger effect on inhibiting right ventricular remodeling than SIL.

Simultaneous integration of telemetered left-ventricular pressure and echocardiography in rats: Minimally-invasive serial pressure-volume relationships in the setting of normal and impaired diastolic function

Simultaneous integration of telemetered left-ventricular pressure and echocardiography in rats: Minimally-invasive serial pressure-volume relationships in the setting of normal and impaired diastolic function

Abstract P3060: Cardiovascular Regulatory Actions of Apelin in Normotensive Rats: Central versus Peripheral Effects

Apelin and its receptor APJ are expressed in both cardiovascular system (CVS) and central nervous system (CNS). Although the apelin/APJ system have already been shown to be involved in cardiovascular homeostasis, the mechanisms in the regulation of CVS are still not fully clear. Thus, this study was undertaken to compare central versus peripheral effect of apelin in the regulation of hemodynamic in SD rats. The chronic recording of blood pressure (BP) and heart rate (HR) were performed using radiotelemetry. Chronic infusion of apelin-13 (100 μg/kg/day) into the lateral cerebral ventricle using osmotic minipumps significantly elevated BP by 15.2±0.9 mmHg, The water intake was also increased from 38±2 to 51±3 ml/day before and after brain infusion of apelin-13. However, the HR was not significantly altered. Furthermore, this chronic pressor effect of apelin-13 was associated with a dramatic increase in the number of Fra-LI positive neurons within the paraventricular nucleus (PVN) and nucleus tractus solitarii (NTS), which were measured with immunohistochemistry using c-Fos antibodies, suggesting an elevated neuronal activity in the brain cardiovascular regulatory areas. Thus, apelin-13 was microinjected into the PVN to confirm the neuronal effect on the BP. The BP of rats was recorded using femoral arterial cannulation. The results demonstrated that acute microinjection of apelin-13 into the PVN significantly increased BP and HR. In peripheral CVS, acute intravenous injections of apelin-13 induced a transient reduction in BP by 25±3 mmHg as expected. Surprisingly, in the same group of rats, the cardiac contractility (dP/dt Max from 8131±512 to 7822±484 mmHg/s) was not significantly altered by apelin-13. In addition, chronic subcutaneous infusion of apelin-13 did not significantly alter either BP or cardiac contractility, which were detected with ratiotelemetry and echocardiography in rats. In conclusion, peripheral administration of apelin-13 only induced a transient decrease in BP without chronic BP regulatory and cardiotonic effects. In contrast, central application of apelin-13 leaded to a chronic elevation in the BP, suggesting that apelin-13 acting as an important neuropeptide in the CNS may contribute to the long-term control of BP.

Effects of mature rehmannia root extract on PDGF and bcl-2 in rat myocardial tissue after myocardial infarction

Objective To observe the effect of mature rehmannia extract on platelet derived growth factor (PDGF) and b-cell lymphoma-2 (bcl-2) 2 in myocardial tissue of rats with myocardial infarction. Methods A total of 30 healthy SD rats were randomly divided into blank group, model group and rehmannia glutinosa group with 10 rats in each group. Myocardial infarction models were established in rats of model group and prepared Rehmannia glutinosa group. The rats in the prepared rehmannia glutinosa group were subcutaneously injected with the extract of the prepared Rehmannia glutinosa 4 g/kg. The rats in the blank group and the model group were subcutaneously injected with the same volume of saline. Once a day for 15 days. The cardiac function was measured by echocardiography in rats. The HE staining was used to observe the histopathological changes of myocardium. The levels of PDGF and Bcl-2 in myocardium were detected by ELISA. The levels of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (BFGF) and CD34 protein were detected by immunoturbidimetry. Results Compared with the model group, the levels of LVDd, LVDs, LVEDs and LVESV in the Rehmannia glutinosa group were significantly decreased (P<0.05) and LVEF was significantly increased (P<0.05), while the levels of PDGF (0.53 ± 0.02 g/ml vs. 0.35 ± 0.01 g/ml), Bcl-2 (1.04 ± 0.20 g/ml vs. 0.84 ± 0.12 g/ml), VEGF (85.24 ± 12.45 pg/ml vs. 65.26 ± 10.06 pg/ml), BFGF (86.27 ± 6.56 pg/ml vs. 62.26 ± 4.37 pg/ml) and CD34 (102.36 ± 10.52 pg/ml vs. 26.37 ± 3.94 pg/ml) in in the Rehmannia glutinosa group were significantly increased (P<0.05). Conclusions The Rehmannia glutinosa extract can improve the cardiac function of rats with myocardial infarction, Promote the formation of new blood vessels and improve myocardial damage. Key words: Rehmanniae radix praeparata; Extracts; Myocardial infarction; Platelet derived growth factor; Apoptosis; Rats

Minimally‐invasive Serial Assessment of Left‐Ventricular Pressure‐Volume Relationships in Rats: Pilot Evaluation in the Setting of Normal and Impaired Diastolic Function.

IntroductionThe assessment of myocardial mechano‐energetic states is paramount to understand both pathological remodeling and responses to therapeutic interventions. In vivo, such state is determined by the interplay between both load‐independent functional properties (inotropy/lusitropy) and loading conditions. However, albeit most cardiac remodeling occurs over time, tools permitting the serial evaluation of load‐independent cardiac function and energetics responses in the chronic setting are limited, particularly in small animals. This pilot study established the feasibility of serial left‐ventricular (LV) pressure‐volume assessments (and derived mechano‐energetic indices) via the simultaneous integration of telemetered pressures and non‐invasive high‐resolution echocardiography in rats with either normal or acquired impaired diastolic function.MethodsHealthy (CTRL, n = 4) and obese/diabetic/hypertensive rats (ZSF1, n = 6) were instrumented with an analog telemetered (Data Sciences International) micro‐manometer catheter in the LV. Real‐time continuous LV pressures (LVP) and dimensions/volumes (via high‐resolution parasternal long‐axis transthoracic echocardiography) were measured simultaneously. In healthy rats, LV pressure‐volume relationships (LVPV) were determined under anesthesia (isoflurane) before/during inotropic (dobutamine, 5 to 10 μg/kg/min IV) and/or vascular (phenylephrine, 5 to 10 μg/kg/min IV) challenges. In the ZSF1 rats, conscious LVP and anesthetized LVPV data were collectd over the course of disease development (16 to 24 weeks).ResultsSimultaneous LV dimensions and pressures were successfully collected in all animals. LV pressures, dimensions, and derived functional indices remained independently sensitive to the pharmacological challenges. Acutely, PE increased systolic and end‐diastolic pressures (EDP) while shifting the pressure‐volume relationships to the right. DOB increased dP/dtmax and decreased EDP, while shifting the LVPV relationship to the left. Both PE and DOB increased stroke‐work, while having opposite effects in arterial elastance/load (Ea, ↑PE and ↓DOB) (see Fig. A). Meanwhile, ZSF1 rats showed progressive elevations in EDP (12.0 ± 1.6 to 17.5 ± 2.1 mmHg. P &lt; 0.05) and Ea (0.51 ± 0.04 to 0.56 ± 0.05 mmHg/μL, P &lt; 0.05), but preserved ejection fraction (73.5 ± 1.7 to 70.6 ± 2.0%, N.S.) and end‐diastolic dimensions (see Fig. B)ConclusionsTaken together, these experiments demonstrate that telemetered pressures and echocardiography‐derived dimensions can be successfully integrated in vivo in order to generate real‐time and serial (minimally‐invasive) LV pressure‐volume relationships in rats.Support or Funding InformationTelemetry devices were donated by DSIThis abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Evaluation of right ventricle by speckle tracking and conventional echocardiography in rats with right ventricular heart failure.

Speckle tracking echocardiography (STE) has been reported to be a promising technique for evaluating right ventricular (RV) function in the clinical setting. On the other hand, the usefulness of STE for RV evaluation in small animal models has not been clarified, although the rat model is among the most commonly used animal models to develop novel effective treatments against pulmonary hypertension and RV heart failure (HF).We validated the use of STE and conventional echocardiographic variables for evaluating RV functions in a rat model by comparing the echocardiographic values of RVHF rats (n = 12) induced by monocrotaline injection with those of control rats (n = 12).Most conventional echocardiographic variables demonstrated that RVHF rats have significant RV dysfunction. The area under the curve (AUC) values to distinguish RV dysfunction in RVHF rats from normal RV function in control rats using fractional area change (FAC), tricuspid annular plane systolic excursion (TAPSE), RV myocardial performance index (MPI), peak tissue Doppler tricuspid annular velocities at systole (Sa), and at early diastole (Ea) were 0.71, 0.98, 0.79, 0.92, and 0.91, respectively. However, using STE analysis for RV evaluation, limited reproducibility was observed (variability 19-37 %, ICC 0.74-0.88) and the only circumferential strain showed significantly lower absolute values (P = 0.039, AUC = 0.76).To evaluate RV function in rat models, circumferential strain may be useful, however, the reproducibility and diagnostic utility were limited. Conventional echocardiographic variables such as TAPSE, tissue Doppler Sa, and Ea have superior diagnostic utility.

Echocardiography Alone Allows the Determination of Heart Failure Stages in Rats with Pressure Overload

There is currently no standard for the assessment of contractile function in animals. We aimed to determine whether transthoracic echocardiography in rats with chronic pressure overload allows determining the stage of hypertrophy and heart failure (HF). Pressure overload was created by placement of a metal clip around the thoracic aorta at a weight of 40 to 50 g. After 1, 2, 6, 10, and 20 weeks, we performed echocardiography according to the American Heart Association guidelines (n = 26, four to six rats for each time point). We also obtained heart, lung, and body weights and regularly evaluated clinical signs of HF. : Pressure overload caused significant hypertrophy within 1 week. Contractile function was normal until 6 weeks when diastolic dysfunction appeared. After 10 weeks of pressure overload, systolic function decreased. At 20 weeks, hearts were dilated and cardiac index was decreased. These findings correlated with increased lung-to-body weight ratio after 6 weeks and clinical signs of HF after 20 weeks. Echocardiography alone allows the reproducible determination of HF stages after aortic constriction in rats.

Effect of SIRT1 gene on cardiac function and life

AimsTo observe effect of SIRT1 gene on cardiac function and life and study influence of SIRT1 gene on myocardial express of AMPK.MethodsHeart failure model of rats were set up by...

Noninvasive monitoring of cardiac function in a chronic ischemic heart failure model in the rat: Assessment with tissue Doppler and non-Doppler 2D strain echocardiography

ObjectivesFeasibility of noninvasive monitoring of cardiac function after surgically induced ischemic cardiomyopathy with tissue Doppler and non-Doppler 2D strain echocardiography in rats.BackgroundThe optimal method for quantitative assessment of global and regional ventricular function in rats with chronic heart failure for research purposes remains unclear.Methods20 rats underwent suture ligation of the left anterior descending coronary artery via a left thoracotomy to induce ischemic cardiomyopathy. Echocardiographic examination with estimation of left ventricular wall thickness, diameters, fractional shortening, ejection fraction, wall velocities as well as radial strain were performed before and 4 weeks after surgery.ResultsMean LVEF decreased from 70 ± 6% to 40 ± 8% (p < 0.0001) one month after the operation. LVEDD increased from 7 ± 1 mm to 9 ± 1 mm (p < 0.0001), systolic anterior velocity decreased from 0.79 ± 0.25 cm/s to 0.18 ± 0.19 cm/s (p < 0.0001). Radial 2D strain was significantly reduced after myocardial infarction of the septal (18.2 ± 6.6% vs 7.0 ± 5.9%, p < 0.001), anteroseptal (17.3 ± 5.2% vs 4.6 ± 3.0%, p < 0.0001), anterior (18.9 ± 5.9% vs 5.6 ± 2.5%, p < 0.0001), lateral (21.4 ± 4.9% vs 8.1 ± 3.5%, p < 0.0001) as well as posterior myocardial segments (19.3 ± 5.2% vs 15.4 ± 5.5%, p < 0.01). Inferior segments (19.2 ± 7.9% vs 17.8 ± 7.9%, ns) did not change at all.ConclusionIt is feasible to assess dimensions, global function, and regional contractility with echocardiography in rats suffering from chronic heart failure after myocardial infarction. Particularly regional function can be exactly evaluated if tissue Doppler and 2D strain is used.

Effect of streptozotocin-induced diabetes on myocardial blood flow reserve assessed by myocardial contrast echocardiography in rats.

The role of structural and functional abnormalities of small vessels in diabetes cardiomyopathy remains unclear. Myocardial contrast echocardiography allows the quantification of myocardial blood flow at rest and during dipyridamole infusion. The aim of the study was to determine the myocardial blood flow reserve in normal rats compared with Streptozotocin-induced diabetic rats using contrast echocardiography.We prospectively studied 40 Wistar rats. Diabetes was induced by intravenous streptozotocin in 20 rats. All rats underwent baseline and stress (dipyridamole: 20 mg/kg) high power intermittent imaging in short axis view under anaesthesia baseline and after six months. Myocardial blood flow was determined and compared at rest and after dipyridamole in both populations. The myocardial blood flow reserve was calculated and compared in the 2 groups. Parameters of left ventricular function were determined from the M-mode tracings and histological examination was performed in all rats at the end of the study.At six months, myocardial blood flow reserve was significantly lower in diabetic rats compared to controls (3.09 ± 0.98 vs. 1.28 ± 0.67 ml min-1 g-1; p < 0.05). There were also a significant decrease in left ventricular function and a decreased capillary surface area and diameter at histology in the diabetic group.In this animal study, diabetes induced a functional alteration of the coronary microcirculation, as demonstrated by contrast echocardiography, a decrease in capillary density and of the cardiac systolic function. These findings may offer new insights into the underlying mechanisms of diabetes cardiomyopathy.

Evans Blue Staining of Cardiomyocytes Induced by Myocardial Contrast Echocardiography in Rats: Evidence for Necrosis Instead of Apoptosis

High mechanical index (MI) echocardiography with contrast agent has been shown to induce Evans blue staining of cardiomyocytes, seen 1 d after exposure, in addition to contraction band necrosis, seen immediately after exposure. This research examined the roles of necrosis vs. apoptosis in these bioeffects. Myocardial contrast echocardiography at high MI with 1:4 electrocardiogram triggering was performed in anesthetized rats at 1.5 MHz. Histologically observable cell injury was accumulated by infusing a high dose of 50 μL/kg ultrasound contrast media via tail vein for 5 min at the start of 10 min of scanning. Evans blue dye or propidium iodide was injected as an indicator of cardiomyocyte plasma membrane integrity. Histologic sections were stained using the terminal dUTP nick-end labeling (TUNEL) method for labeling nuclei with DNA degradation ( e.g., apoptosis). Evans blue fluorescent cells were counted on frozen sections or on hematoxylin-stained and TUNEL-labeled paraffin sections. In addition, transmission electron microscopy was used to assess potential apoptotic nuclei. Hypercontraction and propidium iodide staining were observed immediately after imaging exposure. Although TUNEL-positive cells were evident after 4 h, these also had indications of contraction band necrosis, and features of apoptosis were not confirmed by electron microscopy. Inflammatory cell infiltration was evident after 24 h. A second, more subtle injury was recognized by Evans blue staining, with minimal inflammatory cell infiltration at the morphologically intact stained cells after 24 h. Apoptosis was not detected by the TUNEL method in the cardiomyocytes stained with Evans blue at 24 h. However, Evans blue–stained cell numbers declined after 48 h, with continued inflammatory cell infiltration. The initial insult for Evans blue–stained cardiomyocytes apparently induced partial permeability of the plasma membrane, which led to gradual degeneration (but not apoptosis) and necrosis after 24 to 48 h. (E-mail: douglm@umich.edu)

Noninvasive monitoring of myocardial function after surgical and cytostatic therapy in a peritoneal metastasis rat model: assessment with tissue Doppler and non-Doppler 2D strain echocardiography

ObjectiveWe sought to evaluate the impact of different antineoplastic treatment methods on systolic and diastolic myocardial function, and the feasibility estimation of regional deformation parameters with non-Doppler 2D echocardiography in rats.BackgroundThe optimal method for quantitative assessment of global and regional ventricular function in rats and the impact of complex oncological multimodal therapy on left- and right-ventricular function in rats remains unclear.Methods90 rats after subperitoneal implantation of syngenetic colonic carcinoma cells underwent different onclogical treatment methods and were diveded into one control group and five treatment groups (with 15 rats in each group): group 1 = control group (without operation and without medication), group 2 = operation group without additional therapy, group 3 = combination of operation and photodynamic therapy, group 4 = operation in combination with hyperthermic intraoperative peritoneal chemotherapy with mitomycine, and group 5 = operation in combination with hyperthermic intraoperative peritoneal chemotherapy with gemcitabine, group 6 = operation in combination with taurolidin i.p. instillation. Echocardiographic examination with estimation of wall thickness, diameters, left ventricular fractional shortening, ejection fraction, early and late diastolic transmitral and myocardial velocities, radial and circumferential strain were performed 3–4 days after therapy.ResultsThere was an increase of LVEDD and LVESD in all groups after the follow-up period (P = 0.0037). Other LV dimensions, FS and EF as well as diastolic mitral filling parameters measured by echocardiography were not significantly affected by the different treatments. Values for right ventricular dimensions and function remained unchanged, whereas circumferential 2D strain of the inferior wall was slightly, but significantly reduced under the treatment (-18.1 ± 2.5 before and -16.2 ± 2.9 % after treatment; P = 0.001) without differences between the single treatment groups.ConclusionIt is feasible to assess dimensions, global function, and regional contractility with echocardiography in rats under different oncological therapy. The deformation was decreased under overall treatment without influence by one specific therapy. Therefore, deformation assessment with non-Doppler 2D strain echocardiography is more sensitive than conventional echocardiography for assessing myocardial dysfunction in rats under oncological treatment.

Contrast Enhanced Echocardiographic Follow-up of Cardiac Remodeling and Function after Myocardial Infarction in Rats

Echocardiography is a reliable and commonly used method to examine cardiac diseases. Recent employment of modern technologies provides new opportunities to study left ventricular (LV) remodeling after myocardial infarction (MI) also in small rodents. LV volumes as most important prognostic parameters can be estimated by noncontrast enhanced echocardiography in rats from M-mode or single cross sections only. In this study, contrast enhanced echocardiography and volume measurements by the biplane method of discs (Simpson’s rule) were applied in rats to monitor remodeling and function after MI. MI was induced in female Sprague-Dawley rats ( n = 26 for MI, and n = 16 for sham). LV remodeling and heart function were serially studied by contrast enhanced echocardiography for 12 to 16 wk. At the end of the observation periods hemodynamic data were additionally measured by left and right heart catheterization. LV end systolic volume (LVESV) measured by biplane method of discs correlated best with LV developed pressure as indicator for severely impaired heart function. Interestingly, LV end systolic area (LVESA) from native short axis view correlated well with LVESV (R 2 = 0.93) and was the second best predictor for depressed heart function. Moreover, left atrial size was a powerful indicator of severely impaired heart function whereas ejection fraction or fractional area change were primarily related to infarct size. In conclusion, contrast enhanced echocardiography in rats is feasible and an economical method to study time-dependent LV remodeling and deterioration of contractile function after MI. (E-mail: Alexander.Deten@vetphys.unizh.ch)

1102 Effect of recent onset diabetes on myocardial blood flow reserve assessed by myocardial contrast echocardiography in rats

1102 Effect of recent onset diabetes on myocardial blood flow reserve assessed by myocardial contrast echocardiography in rats

Magnetic resonance imaging of microvascular leakage induced by myocardial contrast echocardiography in rats

The extent and magnitude of microvascular leakage induced by myocardial contrast echocardiography (MCE) were characterized with contrast-aided magnetic resonance imaging (MRI). Evans blue dye, Definity ultrasound contrast agent and Omniscan magnetic resonance contrast agent were injected intravenously in anesthetized rats suspended in a water bath. Diagnostic ultrasound B mode scans with 1:4 end-systolic triggering were performed at 1.5 MHz using a cardiac phased array scanhead to provide a short axis view of the left ventricle. The in situ peak rarefactional pressure amplitude (PRPA) was 2.0 MPa. Microvascular leakage was characterized by extraction of the dye from tissue samples and by imaging the distribution and concentration of Omniscan within the myocardium. The extracted Evans blue was 2.3 times greater than in shams (P<.05) for heart samples perfused with heparin saline, and 1.6 times greater than shams (not significant) for unperfused samples. The MRI showed the penetration of the ultrasound-induced capillary leakage throughout much of the scan plane. The overall gadolinium content measured by MR showed the same trends as the extracted Evans blue, but was more variable. For pooled data (perfused and unperfused), the exposed samples were significantly increased (P<.05) relative to the sham samples for both Evans blue and gadolinium content. Omniscan leakage was also discernable in two of four MRIs from intact rats (after sacrifice). These results demonstrate a potential for MR mapping of capillary leakage induced by contrast-aided ultrasound, with a possible application to spatial characterization of local drug delivery.