Hypertension continues to be a significant cause of morbidity and mortality, underscoring the need to better understand its early effects on the myocardium. The aim of this study is to determine the feasibility of in vivo longitudinal assessment of cardiac function, particularly diastolic function, in a mouse model of renovascular hypertension. Renovascular hypertension (RVH) was induced in 129S1/SvImJ male mice (n=9). To assess left ventricular (LV) systolic and diastolic function, M-mode echocardiography, pulsed-wave Doppler echocardiography and tissue Doppler imaging were performed at baseline, 2 and 4 weeks after the induction of renal artery stenosis. Myocardial tissue was collected to assess cellular morphology, fibrosis, extracellular matrix remodeling and inflammation ex vivo. RVH led to a significant increase in systolic blood pressure after 2 and 4 weeks (baseline: 99.26±1.09 mm Hg; 2 weeks: 140.90±7.64 mm Hg; 4 weeks: 147.52±5.91 mm Hg, P<0.05), resulting in a significant decrease in LV end-diastolic volume, associated with a significant elevation in ejection fraction and preserved cardiac output. Furthermore, the animals developed an abnormal diastolic function profile, with a shortening in the E velocity deceleration time as well as increases in the E/e' and the E/A ratio. The ex vivo analysis revealed a significant increase in myocyte size and deposition of extracellular matrix. Non-invasive high-resolution ultrasonography allowed assessment of the diastolic function profile in a small animal model of renovascular hypertension.Hypertension Research advance online publication, 16 May 2013; doi:10.1038/hr.2013.43.

BACKGROUND:

Blocked atrial bigeminy (BAB) and second-degree atrioventricular block with 2:1 conduction block (2:1 AVB) both present as ventricular bradycardia, and can be difficult to distinguish by echocardiography. Since the prognosis and clinical management of these rhythms are very different, an accurate diagnosis is essential.

METHODS:

A retrospective fMCG and pulsed Doppler ultrasound study of ten BAB and seven 2:1 AVB subjects was performed in order to identify parameters that could reliably distinguish BAB from 2:1 AVB.

RESULTS:

Distinguishing BAB from 2:1 AVB with fMCG was relatively straightforward because in BAB the ectopic P-wave (P') occurred very early, resulting in a bigeminal (short-long) atrial rhythm. The normalized coupling interval of the ectopic beat (PP' of blocked beat to PP of conducted beat) was 0.29±0.03. In contrast, echocardiographic assessment of inflow-outflow gave a normalized mechanical coupling interval (AA'/AA) near 0.5, which made it difficult to distinguish BAB from 2:1 AVB. Heart rate distinguished most BAB and 2:1 AVB subjects (82±5.7 vs. 69±4.2 bpm), but was not a completely reliable indicator. In most subjects, BAB alternated with sinus rhythm or other rhythms, resulting in complex heart rate and rhythm patterns.

CONCLUSION:

fMCG can accurately differentiate BAB from 2:1 AVB, based on measurement of PP' interval and PP'/PP ratios. Differential diagnosis with pulsed Doppler, however, was more difficult because the mechanical rhythm did not accurately reflect the magnetic rhythm in BAB. fMCG also allows detailed characterization of the complex heart rate and rhythm patterns that commonly accompany BAB.

To compare ultrasound guidance versus nerve stimulator guidance supraclavicular brachial plexus block for regional hemodynamic changes of upper extremity.Sixty ASA I-II patients scheduled for upper extremity operation were randomly assigned to receive a supraclavicular brachial plexus block guided by either ultrasound (U group, n = 30) or nerve stimulation (N group, n = 30).20 ml mixture of equal volumes of 2% lidocaine and 0.75% ropivacaine was injected in both groups. Regional hemodynamic parameters were measured in the ipsilateral ulnar artery and radial artery, using pulsed-wave Doppler ultrasound, before and 30 minutes after the block. Regional hemodynamic parameters included peak systolic velocity (PSV), end-diastolic velocity (EDV), time averaged maximum velocity (TAMAX), resistance index (RI), pulsatility index (PI), cross-sectional area (Area) and Blood flow (Q). The intensity of sensory block was measured at 30 minutes after the block.There was no significant difference in the hemodynamic parameters of ulnar artery and radial artery before the block between two groups. Compared with N group, EDV, TAMAX and Q of ulnar artery were higher in U group (1.88-fold, 1.71-fold and 1.84-fold)(P < 0.01 or P < 0.05), PI and RI of ulnar artery were lower in U group (P < 0.01) at 30 minutes after the block, EDV of redial artery was higher in U group (1.47-fold) (P < 0.01), PI and RI of redial artery were lower in U group (P < 0.05) at 30 minutes after the block. Comparing the hemodynamic parameters of ulnar artery and radial artery with complete block between two groups at 30 minutes after the block, EDV, TAMAX and Q of ulnar artery in U group were higher than that in N group (1.68-fold, 1.55-fold and 1.62-fold) (P < 0.01 or P < 0.05), PI of ulnar artery in U group was lower than that in N group (P < 0.01), EDV and TAMAX of redial artery in U group was higher than that in N group (1.54-fold and 1.26-fold) (P < 0.01 or P < 0.05), PI and RI of redial artery in U group was lower than that in N group (P < 0.05). The rate of complete block in U group was higher than that in N group (28/30 vs 22/30, P < 0.05).Ultrasound-guided supraclavicular brachial plexus block enhance the degree of sympathetic block of upper extremity, especially of ulnar artery and increase the blood flow of ulnar artery compared with nerve stimulator.

BACKGROUND:

The feeding interval is an important factor in enteral feeding of premature infants. We investigated postprandial intestinal blood flow in stable very-low-birth-weight infants fed at 2 h and 3 h intervals.

METHODS:

We used pulsed wave Doppler ultrasound to measure blood flow velocity of the superior mesenteric artery (SMA) before feeding and at 15, 30, 45, and 60 min after feeding. Measurements were made on the day of starting enteral nutrition (1or 2 days of age), and at 3 and 5 days of age. A total of 21 studies were performed in 7 infants fed every 2 h, and 54 studies were performed in 18 infants fed every 3 h.

RESULTS:

In infants fed every 2 h, SMA blood flow velocity increased from before feeding to 30 min after feeding, and then decreased at 60 min after feeding. In infants fed every 3 h, SMA blood flow velocity increased after feeding, reaching a peak at 30 min. The correlation coefficients between the volume of milk per feed and the postprandial increase in time-averaged mean blood flow velocity were 0.398 (P = 0.074, n = 21,) and 0.597 (P = 0.000, n = 54,) in infants fed at 2 h and 3 h intervals, respectively.

CONCLUSIONS:

SMA blood flow velocity significantly increased after feeding in infants fed at 2 h and 3 h intervals. The volume of milk per feed might affect the postprandial increase in SMA blood flow velocity.

PURPOSE:

The study's purpose was to investigate the age-related changes in diastolic filling parameters in the aging hearts of active C57Bl/6J mice throughout the lifespan to indicate optimal age periods for improvements in resting diastolic parameters.

METHODS:

Fourteen C57Bl/6J mice (seven male and seven female) were individually housed at eight weeks of age in cages with a running wheel, magnetic sensor and digital odometer. Duration, distance and running velocity were recorded daily. Fourteen additional mice C57Bl/6J mice (seven male and seven female) were placed in individual cages without running wheels at eight weeks of age. Pulsed-wave Doppler transmittal inflow recordings with a SONOS 5500 ultrasound and 15-6L ultrasound probe were used to image the left ventricle every four weeks throughout the lifespan.

RESULTS:

Peak E wave filling velocities were significantly greater by the start of the second quarter of the lifespan in the mice with access to running wheels (p<0.0001). Peak E wave velocities improved in both groups during the first half of the lifespan (p<0.0001) and declined throughout the second half of the lifespan (p<0.0001). E:A filling ratio was significantly greater for the physically active mice by the start of the second quarter of the lifespan (p<0.0001) and continued throughout most of the remainder of the lifespan (p<0.0001). No differences were observed between the two groups of mice with Peak A wave filling velocities (p>0.05). Similar findings were observed when corrected for resting heart rate.

CONCLUSION:

Lifelong physical activity resulted in greater diastolic filling parameters by the second quarter of the lifespan highlighting the clinical importance of regular aerobic activity in young adulthood as a mechanism for improved left ventricular performance with aging.

Images of tumor mechanical properties provide important insights into malignant-cell processes manifest by extracellular matrix (ECM) stiffening and remodeling. This article presents a pilot study measuring in vivo mechanical-property characteristics of rodent mammary tumors using an ultrasonic shear-wave imaging technique. Shear waves are generated by a needle inserted into the tumor of anesthetized rodents that is vibrated harmonically between 50 and 450 Hz. Particle motion in the tumor associated with the radiation of cylindrical shear waves is imaged using pulsed-Doppler ultrasound techniques. Estimating the spatial gradient of shear-wave phase along the direction of propagation at frequencies in the measurement range yields shear-speed dispersion curves. Measured dispersion curves were fit to those predicted by three different rheological models to estimate the elastic and viscous coefficients of the complex shear modulus. The investigation was performed in vivo on four rat-mammary fibroadenoma tumors and five xenograft mouse-mammary carcinoma tumors. Each tumor was subsequently excised for histological imaging and composition analysis. Collagen composition was measured using hydroxyproline assays that were then correlated with mechanical measurements. The goal was to relate soft-tissue mechanical behavior to biological characteristics of tumor structures, specifically the collagenous ECM protein content. The choice of rheological model and the effects of artifacts induced by shear-wave reflections at internal tissue boundaries are carefully examined in this article. Addressing these issues is of great importance when selecting force-excitation methods and modulus estimation method to assess intrinsic tissue properties responsible for disease-specific elastographic contrast.

Transgenic mice displaying abnormalities in cardiac development and function represent a powerful tool for the understanding the molecular mechanisms underlying both normal cardiovascular function and the pathophysiological basis of human cardiovascular disease. Fetal and perinatal death is a common feature when studying genetic alterations affecting cardiac development. In order to study the role of genetic or pharmacologic alterations in the early development of cardiac function, ultrasound imaging of the live fetus has become an important tool for early recognition of abnormalities and longitudinal follow-up. Noninvasive ultrasound imaging is an ideal method for detecting and studying congenital malformations and the impact on cardiac function prior to death. It allows early recognition of abnormalities in the living fetus and the progression of disease can be followed in utero with longitudinal studies. Until recently, imaging of fetal mouse hearts frequently involved invasive methods. The fetus had to be sacrificed to perform magnetic resonance microscopy and electron microscopy or surgically delivered for transillumination microscopy. An application of high-frequency probes with conventional 2-D and pulsed-wave Doppler imaging has been shown to provide measurements of cardiac contraction and heart rates during embryonic development with databases of normal developmental changes now available. M-mode imaging further provides important functional data, although, the proper imaging planes are often difficult to obtain. High-frequency ultrasound imaging of the fetus has improved 2-D resolution and can provide excellent information on the early development of cardiac structures.

OBJECTIVE:

To test the hypothesis that clinically relevant vessels can be visualized and interrogated with Doppler recording during the second half of pregnancy at an output energy below the currently advocated limits without loss of information.

DESIGN:

Observational cross-sectional study.

SETTING:

Tertiary fetal medicine center. SAMPLE: Based on a power calculation for equivalence studies, we recruited 65 pregnant women.

METHODS:

Ultrasound examination was performed at 18, 24, or 36 weeks of gestation. The umbilical artery, middle cerebral artery, ductus venosus, and both uterine arteries were identified using color Doppler, and the blood velocities were measured using pulsed wave Doppler at a thermal index for bone (TIB) of 1.0. This procedure was repeated at TIB values of 0.5 and 0.1. The depth of Doppler recording was noted.

MAIN OUTCOME MEASURES:

Visualization of the vessels by color Doppler at all power levels and any systematic changes or increased variance of the recorded parameters with decreasing power level.

RESULTS:

All vessels could be visualized by color Doppler and their flow velocities measured using pulsed wave Doppler in all participants and at all power levels. There were no systematic changes or increased parameter variance when reducing the power level, despite the insonation depth being significantly greater than in early pregnancy.

CONCLUSIONS:

Reducing the ultrasound power from TIB 1.0 to 0.1 does not alter color Doppler visualization or pulsed wave Doppler measurements in the second half of pregnancy. The lower power level can be recommended as a starting point for clinical examinations throughout pregnancy. © 2013 The Authors Acta Obstetricia et Gynecologica Scandinavica © 2013 Nordic Federation of ocieties of Obstetrics and Gynecology.

Many authors have found that diastolic retrograde arterial flow is associated with increased stiffness of the arterial wall. Most of the studies were based in femoral or brachial artery examination. As the abdominal aorta is a large vessel routinely explored in abdominal ultrasound scans, we decided to study whether it could be useful for early identification of abnormalities of the arterial wall. Sixteen young and 16 old, healthy patients matched for sex, weight and height were studied using pulsed Doppler at the level of the abdominal aortic bifurcation. Different hemodynamic factors were measured and compared to establish the systolic and diastolic function of this artery. Triphasic wave pattern was present in 14 of 16 patients in the younger group and only in 4 of 16 in the older group. In addition, diastolic retrograde arterial flow duration and retrograde components of diastolic phase were more prominent in the advanced age group. Increased retrograde flow and incapacity to impulse arterial flow forward during diastolic time are early markers of vascular wall deterioration that can be observed easily in the abdominal aorta during routine abdominal ultrasound scans.

This comparative ultrasound study included 210 patients aged 65-80 years with non-valvular atrial fibrillation treated with the use of 4 different therapeutic modalities. Intake of perindopril, valsartan, valsartan + rozuvastatin, and lercanidipine resulted in a rise in distension index of common carotid artery, decrease of rigidity coefficient of the aortic wall and increase of the pulsed wave propagation speed. Combination of valsartan (80-160 mg/d) and rozuvastatin (10 mg/d) had the most pronounced effect on the vascular wall compliance compared with other modalities and reduced the frequency of ischemic stroke, myocardial infarction, and mortality. It is concluded that therapy of non-valvular atrial fibrillation in elderly patients with valsartan + rozuvaststin is the optimal strategy for the improvement of elastic properties of the vascular wall and reduction of the frequency of cardiovascular complications.