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At least 1,441 records · Page 80Linked to original sources
PubMed1995

M-mode magnetic resonance imaging: a new modality for assessing cardiac function.

Magnetic resonance imaging (MRI) studies of the heart have been used for some years, but there are few tools available to quantify cardiac motion. A method has been developed that creates an M-mode MRI image, analogous to the one used in echocardiography, to display motion along a line as a function of time. The M-mode image is created from MRI images acquired with an ordinary gradient echo cine sequence. In a cinematographic display of the images, a cursor line can be positioned in order to determine the orientation of the measurement. A resampling algorithm then calculates the appearance of the M-mode image along the cursor line. The MRI method has been compared to echocardiographic M-mode in a phantom study and by measuring mitral and tricuspid annulus motion in 20 normal subjects. The phantom study showed no significant differences between MRI and echocardiographic M-mode measurements (difference < 1 mm). The annulus motion exhibits a similar pattern using both methods and the measured amplitudes are in close agreement. M-mode MRI provides similar information to echocardiography, but the cursor line can be placed arbitrarily within the image plane and the method is thus not limited to certain acoustic windows. This makes M-mode MRI a promising technique for assessing cardiac motion.

Adult↗
PubMed2006

Bone marrow mesenchymal stem cells differentiate into functional cardiac phenotypes by cardiac microenvironment.

Heart attacks and congestive heart failure remain among the world's most prominent health challenges despite the many breakthroughs. Bone marrow mesenchymal stem cells (BMSCs) have the potential to transdifferentiate into myocytes if an appropriate cardiac environment is provided. This study is meant to investigate the ability of BMSCs to differentiate into cardiomyocytes in a conditioned medium. BMSCs were isolated from rat femurs and tibias using Percoll gradient centrifugation method. Cells were expanded as undifferentiated cells in culture for more than 3 passages and their phenotypes were identified with flow cytometer. BMSCs were cocultured with neonatal rat ventricular myocytes in a rate of 1:10 separated by semipermeable membrane. BMSCs marker of CD29 were highly expressed (98.89+/-1.2%); however, CD34 could hardly be identified (5.61+/-0.1%). After coculturing with myocytes, some of BMSCs showed contraction which became more regular and more vigorous. As assessed by RT-PCR, SERCA2 and RyR(2) were expressed by newly formed cells from 1 to 3 weeks. Immunostaining of newly differentiated BMSCs revealed positivity for cTnT. Some of these cells were positive for sarcomeric alpha-actinin, desmin, cTnT, and cTnI. Western blotting showed that cTnI protein expression was upregulated in these cells from 1 to 3 weeks. Newly formed BMSCs exhibited ultrastructural features of sarcomere formation and inward rectifier potassium current (I(K1)). It is concluded that BMSCs possess the potential to differentiate into cardiomyocytes in the cardiac environment. BMSCs provide an excellent model for development of stem cell therapeutics, and their potential in the cardiac repair under various pathological conditions.

Animals↗
PubMed1986

[Behavior of contractile and functional cardiac parameters of patients in the early stage of type I diabetes mellitus].

The echocardiographically obtained data for contractility and function of the heart showed that patients with type I diabetes mellitus known up to 1 year at the age of 29 +/- 7 years showed more unfavourable parameters concerning the contraction fraction of the two chambers and the ejection fraction of the left ventricle and had also a larger diastolic diameter of the posterior wall, those patients were compared with persons with healthy metabolism aged 43 +/- 2 years. Since the two groups did not show any evidences as to cardiovascular diseases, the echocardiographic results might be explained as early symptoms of a diabetic cardiopathy.

Adult↗
PubMed1994

Cardiac function in malnourished children.

The cardiovascular status of severely malnourished children was characterized before, during, and after nutritional rehabilitation. In most children with third-degree malnutrition, cardiac mass was decreased on admission to the hospital and recovered subsequent to nutritional therapy. All children had echocardiographic and Doppler measurements indicative of impaired ventricular function which significantly improved during the course of hospitalization, as evidenced in part by the change in fractional shortening (P = 0.015), mean velocity of circumferential fiber shortening (P = 0.038), and systolic time interval (P = 0.030). We conclude that children with primary third-degree malnutrition not only have cardiac muscle wasting, but also have inherent ventricular dysfunction as the result of severe malnutrition that responds to nutritional therapy. Particular care with fluid administration is imperative in the first week of therapy, when heart function is the most compromised.

Child, Preschool↗
PubMed1999

Effect of estrogen replacement therapy on cardiac function in postmenopausal women with and without flushes.

Left ventricular heart function and its response to long-term estrogen replacement therapy was assessed in 30 postmenopausal women, 20 of whom had modest to severe hot flushes and 10 of whom had never had them. Continuous transdermal estradiol was given to women who had surgically induced menopause, and a combination of transdermal estradiol and sequential medroxyprogesterone acetate was given to those who had spontaneous menopause. Left ventricular systolic and diastolic function was evaluated by complete two-dimensional M-mode and pulsed Doppler echocardiography before and after 6 and 12 months of therapy. The parameters assessed were: systolic and diastolic blood pressure, heart rate, cardiac septal and posterior wall dimensions, left ventricular end-systolic and end-diastolic dimensions and volumes, ejection fraction (EF), ejection time, peak left ventricular outflow velocity (PFV), flow velocity integral (FVI), acceleration time (AT), mean acceleration of systolic flow (MA), duration of early and late filling phase, peak velocity of the early (E) and late (A) mitral flow, and A/E velocity ratio. Although no difference in chamber and wall dimensions between flushers and non-flushers was found, women with hot flushes had lower (not significantly) EF, PFV, FVI, MA, blood pressure and heart rate before therapy. Twelve-month estrogen replacement therapy significantly reduced cardiac wall dimensions and improved systolic function in both flushers and non-flushers. However, stroke volume, EF and MA were increased whereas systolic blood pressure and heart rate were decreased more in flushers. Also, the increase in E mitral flow and decrease in A/E were more pronounced in flushers. Thus, although estrogen replacement therapy significantly improves heart function in healthy postmenopausal women, there appears to be some minor differences in response between flushers and non-flushers.

Administration, Cutaneous↗
PubMed1988

Optimal hematologic variables for oxygen transport, including P50, hemoglobin cooperativity, hematocrit, acid-base status, and cardiac function.

The two important blood properties that affect O2 delivery are the O2 equilibrium curve (OEC) and blood viscosity with its subsequent effect on flow (cardiac output). To quantitate these properties blood OEC's were analyzed in terms of the Adair 4-step oxygenation model and the resulting parameters were used to construct a computer nomogram to reproduce the OEC at any combination of effectors that regulate P50 (pH, PCO2, and 2,3-DPG). In this way, the P50 could be changed systematically and the effects on overall O2 transport could be studied. Hematocrit-viscosity-cardiac output relationships were taken from the literature and validated using data from human subjects with various pathological states and high-altitude natives. A model was then developed, using the Bohr integration, to predict the O2 transport function of blood under a variety of conditions including exercise and hypoxia. The results indicate that the optimal hematocrit is about 43-45%, even in hypoxia. The optimal P50, however, depends on the availability of O2: a high P50 is not necessarily beneficial in hypoxia and high cardiac output states. This model and general approach should prove useful in the design of blood substitutes.

2,3-Diphosphoglycerate↗
PubMed1998

Histamine H3 activation depresses cardiac function in experimental sepsis.

In the heart, histamine (H3) receptors may function as inhibitory presynaptic receptors that decrease adrenergic norepinephrine release in conditions of enhanced sympathetic neural activity. We hypothesized that H3-receptor blockade might improve cardiovascular function in sepsis. In a canine model of Escherichia coli sepsis, we found that H3-receptor blockade increased cardiac output (3.6 to 5.3 l/min, P < 0.05), systemic blood pressure (mean 76 to 96 mmHg, P < 0.05), and left ventricular contractility compared with pretreatment values. Plasma histamine concentrations increased modestly in the H3-blocker-sepsis group compared with values obtained in a nonsepsis-time-control group. In an in vitro preparation, histamine H3 activation could be identified under conditions of septic plasma. We conclude that activation of H3 receptors may contribute to cardiovascular collapse in sepsis.

Animals↗
PubMed1998

[Changes of tissue oxygenation and relationship between oxygen delivery and consumption in patients with poor cardiac function undergoing valve replacement].

To study the relationship between oxygen delivery(DO2) and consumption(VO2) and tissue oxygenation in patients during cardiac valve replacement, DO2, VO2, arterial blood lactate (ABL) SvO2 were measured. The results showed a poor correlation between DO2 and VO2 and a normal tissue oxygenation before CPB. There was a good positive correlation between DO2 and VO2 within 20 h after the end of CPB(P < 0.01), and changes of ABL and SvO2 showed tissue hypoxia. The level of ABL in patients showing O2 supply-dependency was lower, and SvO2 was higher than those in 15 patients showing O2 supply-independency, respectively (P < 0.05). These data suggest that O2 supply-dependency was existed after the end of CPB, and there was a good correlation between O2 supply-dependency and ABL. It might not exclude tissue hypoxia in O2 supply-independency and normal level of SvO2.

Adult↗