OBJECTIVETo evaluate the changes of cerebral blood flow (CBF) with real-time contrast-enhanced ultrasound (CEU) in a canine model of acute cerebral ischemia.

METHODSCerebral perfusion was assessed in 6 dogs subjected to craniotomy with CEU at the time of 0, 30, 60, 90 and 120 min after occlusion of the left common carotid artery (LCCA). The microvascular volume (A) and blood flow velocity (beta) in the brain were measured from the time-versus-acoustic intensity plots, and the value of Axbeta were calculated. 99mTc-ECD brain single photon emission computed tomography (SPECT) was performed on the day before the experiment and at 120 min after LCCA occlusion. The radioactive counts on both sides of the cerebral cortex were calculated.

RESULTSA significant correlation was found between Axbeta from CEU and volume of the blood flow of the CCA from Doppler flowmetry. A, beta and Axbeta values varied significantly between the different time points (P>0.001). The ipsilateral hemisphere showed a low-perfusion state while the contralateral hemisphere showed a high-perfusion state immediately after the occlusion.

CONCLUSIONSThe changes of beta is the main regulation mechanism during acute cerebral ischemia in dogs.

Animals ; Blood Flow Velocity ; Brain ; blood supply ; Brain Ischemia ; diagnostic imaging ; Cerebrovascular Circulation ; Dogs ; Male ; Regional Blood Flow ; Ultrasonography

OBJECTIVETo investigate the feasibility of bone marrow mesenchymal stem cell (MSC) transplantation with ultrasound-targeted microbubble destruction.

METHODSTwenty-one Wistar rats were divided into MSCs-iv group (MSCs-iv), ultrasound+MSCs-iv group (US+MSCs-iv), ultrasound+microbubble+MSCs-iv group (US+MB+MSCs-iv) with intravenous MSC transfer, ultrasound and microbubble treatment as indicated. The skeletal muscles were obtained from the rats for microscopic examination with HE staining. The hindlimb gracilis and semimembranosus muscles were sampled 7 days after MSC transplantation, and the transplanted MSCs were detected by immunohistochemistry. The vital organs were collected from rats in US+MB+MSCs-iv group for immunohistochemistry.

RESULTSIn US+MB+MSCs-iv group, HE staining demonstrated the presence of red blood cell leakage into the tissue space in the gracilis and semimembranosus muscles, and immunohistochemistry identified large numbers of transplanted MSCs in the the gracilis and semimembranosus muscles and the spleen, whereas no labeled cells were detected in the skeletal muscles in other groups.

CONCLUSIONUltrasound-targeted microbubble destruction provides a useful means for enhancing the efficiency of stem cell transplantation.

Animals ; Bone Marrow Cells ; cytology ; Cell Movement ; radiation effects ; Female ; Male ; Mesenchymal Stem Cell Transplantation ; methods ; Mesenchymal Stromal Cells ; cytology ; Microbubbles ; Muscle, Skeletal ; cytology ; Rats ; Rats, Wistar ; Ultrasonics

OBJECTIVETo study value of velocity vector imaging (VVI) in assessment of normal left ventricular diastolic function and the corresponding reference values.

METHODSNinety-seven healthy subjects were selected by combined clinical, ultrasound, and NT-proBNP examinations. Using a Siemens Acuson Sequoia C512 echocardiograph, VVI was adopted to examine the myocardial early diastolic velocity (E) of the septal, lateral, anterior, inferior, anterior septum, and posterior wall of the left ventricle at the level of mitral annulus. The images were analyzed for VVI and the mean diastolic velocity (E(m)) and hence the E/E(m) ratio was calculated based on the offline workstation interface.

RESULTSThe reference range of E/E(m) ratio derived from the data of the 97 healthy subjects was (unilateral boundaries with 95% limit) and (1, 22.935), was (1, 22.300) in male subjects and (1, 24.766) in female subjects. The reference E/E(m) range was (0, 22.413) in male subjects under 50 years of age, (1, 24.766) in female subjects under 50 years, (1, 22.300) in male subjects over 50 years, and (1, 24.766) in female subjects over 50 years.

CONCLUSIONVVI is a good method for non-invasive evaluation of the left ventricular diastolic function and provides an accurate and reliable means for clinical assessment of the left ventricular diastolic function.

Adolescent ; Adult ; Aged ; Blood Flow Velocity ; physiology ; Diastole ; physiology ; Echocardiography ; methods ; Female ; Humans ; Male ; Middle Aged ; Reference Values ; Ventricular Function, Left ; physiology ; Young Adult

OBJECTIVETo investigate the effects of nitroglycerine (NTG) on myocardial oxygen metabolism and regional cardiac function in canine hearts with a stable systemic hemodynamics in situ.

METHODSEight anesthetized open-chest dogs with flow-limited left anterior descending branch of the coronary artery or left circumflex artery (LCx) stenosis were studied. The percentage of ventricular wall thickening (%WT) was measured with quantitative two-dimensional echocardiography (2DE), myocardial blood flow (MBF) with radiolabeled microspheres and tissue oxygen pressure (tPO(2).) with oxygen-dependent quenching of phosphorescence. 2DE was performed and radiolabeled microspheres and Pd-porphyrin injected in the dogs at rest during intracoronary infusion of 0.3-0.6 mg x kg(-1) x min(-1) of NTG. Myocardial oxygen consumption (MVO(2), ml x min(-1) x 100 g(-1)) was calculated as the multiplication product between the arterio-venous oxygen content difference and MBF, and myocardial O(2) delivery as the product between arterial oxygen content and MBF.

RESULTSAs compared with the baseline, NTG increased %WT and MBF significantly in both normal and ischemic beds (P<0.05). There was a significant increase in MVO(2) during NTG infusion in the ischemic bed (P<0.05) in comparison with that measured at rest. NTG, however, significantly increased the ability of myocardial O(2) delivery in both normal and ischemic beds (P<0.05), therefore tPO(2) was still higher in the ischemic bed during NTG infusion than that at rest (P<0.05). The percentage increment in tPO(2) was significantly greater in the ischemic bed than percentage MBF increment.

CONCLUSIONSNTG enhances myocardial oxygen concentration in normal and ischemic myocardium and may increase oxygen release to the ischemic myocardium in vivo. NTG may have a positive inotropic effect on regional cardiac function. In addition to direct effect on vascular tone, NTG plays important roles in the cardiovascular system by modulating myocardial oxygen metabolism and contractile function.

Animals ; Dogs ; Echocardiography ; Hemodynamics ; Myocardium ; metabolism ; Nitroglycerin ; pharmacology ; Oxygen Consumption ; drug effects

OBJECTIVETo evaluate the effects of polyethylene oxide (PEO) on blood perfusion in hind limb skeletal muscles in a rat model of chronic hind limb ischemia.

METHDOSTwelve rat models of chronic hind limb ischemia established by unilateral femoral artery ligation were randomized into PEO and control groups (n=6) and treated with intravenous infusion of PEO and saline through the internal jugular vein every other day for 2 weeks. Contrast-enhanced ultrasonography was performed after the treatments to evaluate the blood flow in the skeletal muscles at different time points and blood flow reserve in the ischemic hind limbs on day 28.

RESULTSStarting from 7 days after femoral artery ligation, blood flow in the ischemic hind limb skeletal muscles was significantly higher in PEO group than in the control group (P<0.05). On day 28, blood flow reserve in the ischemic hind limb was significantly higher (P=0.012), and blood volume was significantly increased in PEO group as compared that in the control group (P=0.024).

CONCLUSIONSPEO can increase blood flow, blood flow reserve and vascular volume in the hind limb skeletal muscles in rats with chronic hind limb ischemia, suggesting that PEO can promote angiogenesis and arterial formation by increasing blood flow shear stress to improve blood supply of ischemic hind limbs.

OBJECTIVETo investigate the changes and the effects of captopril on the renal blood flow and microvascular perfusion in dogs with acute cardiac insufficiency.

METHODSAcute cardial insufficiency was induced by combining occlusion of the left anterior descending artery with right ventricular pacing in 12 mongrel dogs. The ascending aorta and left kidney were dissected and ultrasonic flow probes were placed on ascending aorta and renal artery to monitor cardiac output (CO) and renal blood flow (RBF). Contrast-enhanced ultrasound of the kidney was performed as CO was reduced to 25% (LCO25%) and 50% (LCO50%) from the basic measurement and microvascular flow velocity (beta), microvascular volume (A) and microvascular blood flow (renal cortex) were observed. After CO reduced to 50%, captopril 1 mg/kg and 2 mg/kg were injected successively and contrast-enhanced ultrasound of the kidney were performed again before and after injection.

RESULTSAt baseline, CO, RBF, CXbeta (beta of renal cortex), A and A x beta were (1.46 +/- 0.16) ml/min, (107.5 +/- 35.7) ml/min, 1.39 +/- 0.14, 120.3 +/- 14.8 and 167.4 +/- 25.0, respectively. After the LCO25% was reached, RAF, CXbeta, A and A x beta decreased to (72.50 +/- 32.4) ml/min, 0.87 +/- 0.082, 117.6 +/- 13.1, and 102.6 +/- 15.5, respectively. The corresponding values after the LCO50% was reached were (44.1 +/- 17.2) ml/min, 0.61 +/- 0.039, 106.9 +/- 12.0, and 64.7 +/- 8.83, respectively. It is suggested that the volume of the renal microvasculature remained stable until the LCO50% was reached. When captopril 1 mg/kg and 2 mg/kg were injected successively at LCO50%, MAP decreased from (85.4 +/- 7.8) mm Hg to (78.7 +/- 7.3) mm Hg and to (69.1 +/- 6.3) mm Hg (P < 0.05), respectively, while CO increased from 0.73 +/- 0.084 to 0.83 +/- 0.065 and to 0.9 +/- 0.054 (P < 0.05), respectively. RBF increased from (44.1 +/- 17.2) ml/min to 60.3 +/- 17.8 and to 79.4 +/- 17.8 (P < 0.05), respectively. After captopril 1 mg/kg and 2 mg/kg were injected, the increased flow ratios with CO were 0.15 +/- 0.084 and 0.31 +/- 0.011, respectively, and with RBF were 0.29 +/- 089 and 0.522 +/- 0.040, respectively. The increased renal blood flow ratio was higher than that of CO after captopril was used. The corresponding increases were from 0.61 +/- 0.039 to 0.75 +/- 0.020 and to 0.86 +/- 0.027 for CX beta, from 106.9 +/- 11.9 to 115.4 +/- 11.1 and to 116.6 +/- 8.9 for A, from 64.7 +/- 8.83 to 87.0 +/- 8.6 and to 100.6 +/- 8.9 for A x beta, respectively.

CONCLUSIONThe renal microvasculature plays a role by keeping its volume stable in the protection against renal ischemia when acute cardiac output decreases slightly. The role of captopril to improve renal microvascular perfusion is independent of increased total cardiac output or increased systemic blood pressure.

Angiotensin-Converting Enzyme Inhibitors ; pharmacology ; therapeutic use ; Animals ; Captopril ; pharmacology ; therapeutic use ; Cardiac Output, Low ; complications ; drug therapy ; physiopathology ; Dogs ; Female ; Kidney ; blood supply ; diagnostic imaging ; Male ; Perfusion ; Renal Circulation ; drug effects ; Ultrasonography

OBJECTIVETo evaluate the direct effects of dobutamine as compared to adenosine on the coronary microcirculation in both normal and stenotic segments using myocardial contrast echocardiography (MCE).

METHODSLeft anterior descending (LAD) coronary artery stenosis, which was not flow limiting at rest, was established in 9 dogs. At the baseline and during intracoronary infusion of dobutamine (2 mg.kg(-1).min(-1)) and adenosine (5 mg.kg(-1).min(-1)), the radiolabeled microsphere (RM)-derived myocardial blood flow (MBF) were determined, and the double product (DP) and myocardial vascular resistance (MVR) were calculated. MCE was performed to determine the myocardial blood volume (MBV, represented by A) and microbubble velocity (beta).

RESULTSAs compared to the baseline level, the MBF increased and MVR decreased significantly in both the normal and abnormal beds during infusion of both drugs (P<0.05). In the normal bed, adenosine had no effect on MBV, the decrease in MVR was the result of decreased arteriolar (plus venular) resistance, and the increase in MBF was predominately due to the increase in b (deltabeta/ deltaA=13.6). Dobutamine caused a 28% increase in MBV, responsible for 32% of the decrease in the total MVR, but the increase in MBF arose mainly from the increase in b (deltabeta/deltaA=5.9). In the abnormal bed, both the drugs caused a similar increase in MBF entirely by increasing b, and 14% and 15% of the increases in capillary resistance were associated with the capillary derecruitment during administration of dobutamine and adenosine, respectively.

CONCLUSIONThe direct effects of intracoronary dobutamine infusion on the coronary microcirculation are similar to that of adenosine, and the increase in MBF occurs mostly as the result of increased myocardial blood velocity.

Adenosine ; pharmacology ; Adrenergic beta-Agonists ; pharmacology ; Animals ; Blood Flow Velocity ; drug effects ; Coronary Circulation ; drug effects ; Coronary Stenosis ; diagnostic imaging ; Coronary Vessels ; diagnostic imaging ; Dobutamine ; pharmacology ; Dogs ; Echocardiography ; methods ; Microcirculation ; drug effects ; Vasodilator Agents ; pharmacology

OBJECTIVETo validate the efficacy of velocity vector imaging (VVI) and quantitative tissue velocity imaging (QTVI) for evaluating left ventricular diastolic function.

METHODSFifty-one patients underwent left heart catheterization were included in this study. Mean of peak early diastolic velocity (Em), EF and the ratio of early (E) to late (A) mitral valve flow velocity (E/A) were measured by echocardiography and the ratio of E to Em (E/Em) was calculated. Left ventricular end diastolic pressure (LVEDP) was measured during catheterization examination.

RESULTSE/Em derived from VVI or QTVI was significantly correlated with LVEDP (r = 0.808, P < 0.01 and r = 0.692, P < 0.01, respectively) and the correlation coefficient between VVI and LVEDP was significantly higher than that between QTVI and LVEDP (Z = 2.246, P = 0.025). Em derived from VVI and QTVI also negatively correlated with LVEDP (r = -0.740, P < 0.01 and r = -0.567, P < 0.01) and the correlation coefficient between VVI and LVEDP was significantly higher than that between QTVI and LVEDP (Z = 2.595, P = 0.009). However, there was no correlation between E/A and LVEDP (r = 0.117, P = 0.415).

CONCLUSIONE/Em and Em derived from VVI and QTVI are valuable parameters for evaluating LV diastolic function.

Blood Flow Velocity ; Cardiac Catheterization ; Diastole ; physiology ; Echocardiography ; methods ; Humans ; Mitral Valve ; diagnostic imaging ; physiology ; Reproducibility of Results ; Ventricular Function, Left ; physiology

OBJECTIVETo investigate the effect of therapeutic ultrasound-induced microbubble destruction on the microcirculation of rat skeletal muscle.

METHODSThirty SD rats were randomized into 5 groups (n=6), namely normal saline, microbubble, ultrasound, high-energy ultrasound microbubble and low-energy ultrasound microbubble groups. Before and after the treatments, the diameter and blood flow velocity in the microvessels in the skeletal muscle were measured, and the structural changes of the injured microvessels observed by electron microscopy.

RESULTSMicrobubble cavitation did not produce significant effect on the mean arterial pressure and diameter of microvessels in rat skeletal muscle (P>0.05), but the blood flow velocity was obviously lowered and blood flow volume reduced in the microvessels. The reduction of the flow velocity and blood flow volume and their subsequent recovery were associated with ultrasound energy, and in the low ultrasound energy group, the flow velocity and blood flow volume in the of venules recovered obviously after about 15 min, which, however, took approximately 1 h for the arterioles. In contrast, recovery of the flow velocity and blood flow volume in the microvessels took more than 2 h in the high ultrasound energy group. Cavitation resulted in endothelium cell rupture, widening of the endothelial interspace and entry of the red blood cells into the extravascular tissues as revealed by electron microscopy, but no rupture of the lining endothelium was observed 2 h after the treatment.

CONCLUSIONSEndothelium cell rupture induced by microbubble cavitation may affect the local microcirculation, and lower ultrasound energy exposure is associated with milder endothelial injury and more rapid recovery.

Animals ; Blood Flow Velocity ; Blood Vessels ; pathology ; physiopathology ; Endothelial Cells ; pathology ; ultrastructure ; Female ; Male ; Microbubbles ; Microcirculation ; Microscopy, Electron ; Microspheres ; Muscle, Skeletal ; blood supply ; Rats ; Rats, Sprague-Dawley ; Ultrasonics

OBJECTIVETo assess the value of velocity vector imaging (VVI) and quantitative tissue velocity imaging (QTVI) in assessing left ventricular diastolic function of the dogs with acute myocardial ischemia.

METHODSSix healthy mongrel dogs were subjected to ligation of the left circumflex artery or left anterior descending artery to induce coronary artery stenosis of varying degrees. The mean peak diastolic velocity (Em) of the ventricular walls around the mitral annulus was recorded with VVI or QTVI in the coronary blood flow. The left ventricular end diastolic pressure (LVEDP) was measured with pigtail catheter in the left ventricle.

RESULTSAs the coronary blood flow decreased, LVEDP was gradually increased, and Em measured by VVI or QTVI were also gradually decreased. A good linear correlation was shown between Em measured by VVI or QTVI and LVEDP (r=-0.834, P<0.001, and r=-0.68, P<0.001, respectively). A significant difference was observed in the correlation coefficient between VVI and QTVI (Z=2.625, P=0.0087).

CONCLUSIONVVI and QTVI both provide good noninvasive means for measuring left ventricular diastolic function. VVI, a new echocardiographic modality without angular dependence, is better than QTVI in evaluating left ventricular diastolic function.

Animals ; Disease Models, Animal ; Dogs ; Echocardiography ; methods ; Male ; Myocardial Ischemia ; diagnostic imaging ; physiopathology ; Ventricular Function, Left