Ventricular Volume Measurements Research Articles

Dynamic Brain Phantom for Intracranial Volume Measurements

Knowledge of intracranial ventricular volume is important for the treatment of hydrocephalus, a disease in which cerebrospinal fluid (CSF) accumulates in the brain. Current monitoring options involve MRI or pressure monitors (InSite, Medtronic). However, there are no existing methods for continuous cerebral ventricle volume measurements. In order to test a novel impedance sensor for direct ventricular volume measurements, we present a model that emulates the expansion of the lateral ventricles seen in hydrocephalus. To quantify the ventricular volume, sensor prototypes were fabricated and tested with this experimental model. Fluid was injected and withdrawn cyclically in a controlled manner and volume measurements were tracked over 8 h. Pressure measurements were also comparable to conditions seen clinically. The results from the bench-top model served to calibrate the sensor for preliminary animal experiments. A hydrocephalic rat model was used to validate a scaled-down, microfabricated prototype sensor. CSF was removed from the enlarged ventricles and a dynamic volume decrease was properly recorded. This method of testing new designs on brain phantoms prior to animal experimentation accelerates medical device design by determining sensor specifications and optimization in a rational process.

Comparison of Simpson's Method and Three-Dimensional Reconstruction for Measurement of Right Ventricular Volume in Patients With Complete or Corrected Transposition of the Great Arteries

The right ventricular (RV) volume is commonly measured from magnetic resonance images using Simpson's method from the stack of short-axis images acquired for analysis of the left ventricle. We compared the RV volume measured using Simpson's method to the RV volume measured using 3-dimensional reconstruction and the piecewise smooth subdivision surface (PSSS) method. We studied 6 normal subjects and 18 patients whose right ventricles carried a systemic pressure load, 1/2 with dexto-transposition of the great arteries repaired with an atrial baffle and 1/2 with levo-transposition of the great arteries. The right ventricle was reconstructed from manually traced borders from the short- and long-axis views using the PSSS method. Simpson's analysis was performed on short-axis views alone. The RV volumes were smaller when analyzed using Simpson's method than using the PSSS method. The underestimation averaged 12 +/- 19 ml (7 +/- 12% of PSSS volume; p <0.001), without a significant difference between the groups. The ejection fraction was similar using both methods in patients with transposition of the great arteries and was overestimated in normal subjects. Image review revealed that the volume underestimation using Simpson's method was more frequently due to difficulty in interpreting the basal short-axis images than the apical images. In conclusion, to obtain accurate analysis of the short-axis views for RV volume measurement, it would be helpful to incorporate information from additional images, such as the long-axis views, to assist in delineating this chamber's complex anatomy.

Brain Ventricular Volume and Cerebrospinal Fluid Biomarkers of Alzheimer's Disease

The frequent co-occurrence of Alzheimer's disease (AD) pathology in patients with normal pressure hydrocephalus suggests a possible link between ventricular dilation and AD. If enlarging ventricles serve as a marker of faulty cerebrospinal fluid (CSF) clearance mechanisms, then a relationship may be demonstrable between increasing ventricular volume and decreasing levels of amyloid-beta peptide (Abeta) in CSF in preclinical and early AD. CSF biomarker data (Abeta, tau, and phosphorylated tau) as well as direct measurements of whole brain and ventricular volumes were obtained from the Alzheimer's Disease Neuroimaging Initiative dataset. The ratio of ventricular volume to whole brain volume was derived as a secondary independent measure. Baseline data were used for the group analyses of 288 subjects classified as being either normal (n=87), having the syndrome of mild cognitive impairment (n=136), or mild AD (n=65). Linear regression models were derived for each biomarker as the dependent variable, using the MRI volume measures and age as independent variables. For controls, ventricular volume was negatively associated with CSF Abeta in APOE epsilon4 positive subjects. A different pattern was seen in AD subjects, in whom ventricular volume was negatively associated with tau, but not Abeta in epsilon4 positive subjects. Increased ventricular volume may be associated with decreased levels of CSF Abeta in preclinical AD. The basis for the apparent effect of APOE epsilon4 genotype on the relationship of ventricular volume to Abeta and tau levels is unknown, but could involve altered CSF-blood-brain barrier function during the course of disease.

COMPARISON OF LEFT VENTRICULAR VOLUMES AND EJECTION FRACTION ASSESSMENT BY TWO-DIMENSIONAL ECHOCARDIOGRAPHY COMPARED WITH GATED MYOCARDIAL SPECT IN PATIENTS WITH ISCHEMIC CARDIOMYOPATHY

The aim of this study was to assess accuracy of echocardiography in the measurement of left ventricular ejection fraction (LVEF), enddiastolic volume (EDV) and endsystolic volume (ESV) compared with gated SPECT. A total of 70 patients with left ventricular systolic dysfunction were enrolled to study. Median of the time interval between gated SPECT and echocardiography was 1 hour. Echocardiography was in good agreement with gated SPECT for quantification of LVEF by using Simpson's method in triplane (r=0.88, p<0.001), biplane (r=0.83, p<0.001) and monoplane apical four chamber projections (A4CH) (r=0.71, p<0,001). LVEF measured by SPECT (36.6+/-11.5%) was non-significantly higher then triplane (35.9+/-10%, median dif. 0.4%), biplane (35.7+/-10%, median dif. 0.7%), A4CH monoplane (36.6+/-12.2%, median dif. 0.1%). Echocardiography correlated with SPECT in quantification of EDV using triplane (r=0.8, p<0.001), biplane (r=0.81, p<0.001) and monoplane echocardiography (r=0.76, p<0.001). EDV measured by SPECT (201.1+/-72.5 ml) was significantly different and higher then triplane (174.4,5+/-60.8 ml, median dif. 22.8), biplane (170.9+/-58.4, median dif. 28 ml) and monoplane echocardiography (173.7+/-59.3, median dif. 85.7 ml). Echocardiography correlated with SPECT in quantification of ESV by triplane (r=0.87, p<0.001), biplane (r=0.86, p<0.001) and monoplane echocardiography (r=0.83, p<0.001). ESV measured by SPECT (133.1+/-64.3) was significantly different then triplane (115.1+/-52.1, median dif. 17 ml), biplane (113.2+/-51.5, median dif. 15.5 ml) and A4CH monoplane echocardiography (112.5+/-48.8, median dif. 17.2 ml). Echocardiography is a valid tool for LVEF assessment and systematically underestimates LV volumes compared with gated SPECT in patients with LV systolic dysfunction.

Accuracy of Knowledge-Based Reconstruction for Measurement of Right Ventricular Volume and Function in Patients With Tetralogy of Fallot

We tested the accuracy and reproducibility of knowledge-based reconstruction (KBR) for measuring right ventricular (RV) volume and function. KBR enables rapid assessment of the right ventricle from sparse user input by referencing a database. KBR generates a 3-dimensional surface to fit points that the user enters at anatomic landmarks. We measured the RV volume using KBR from magnetic resonance images in 20 patients with repaired tetralogy of Fallot at end-diastole and end-systole. We entered points in the long- and short-axis and/or oblique views. The true volume was computed by manually tracing the RV borders for 3-dimensional reconstruction using the piecewise smooth subdivision surface method. The reference database included 54 patients with tetralogy of Fallot patients. The KBR values agreed closely with the true values for the end-diastolic volume (r = 0.993), end-systolic volume (r = 0.992), and ejection fraction (EF; r = 0.930). KBR slightly overestimated the end-diastolic volume (4 +/- 10 ml, p = NS), end-systolic volume (1 +/- 9 ml, p = NS), and EF (4 +/- 3%, p = NS). No bias in the error was found by Bland-Altman analysis (p = NS for end-diastolic and end-systolic volume and EF). The KBR volumes had approached the true volumes (235 +/- 93 vs 243 +/- 93, p = 0.012, r = 0.978 for end-diastolic and end-systolic volumes combined) already after the first run and the entry of 19 +/- 3 points. In conclusion, KBR provided accurate measurement of the RV volume and EF with minimal user input. KBR is a clinically feasible alternative to full manual tracing of the heart borders from imaging data.

Role of Sonographic Automatic Volume Calculation in Measuring Fetal Cardiac Ventricular Volumes Using 4-Dimensional Sonography

The purpose of this study was to compare the agreement and reliability of virtual organ computer-aided analysis (VOCAL) and sonographic automatic volume calculation (sonoAVC) for measurements of ventricular volume from fetal heart data sets acquired by 4-dimensional sonography with spatiotemporal image correlation (STIC). We studied 45 volumes from fetuses with normal (n = 30) and abnormal (n = 15) hearts. Spatiotemporal image correlation data sets were frozen in end systole and end diastole, and ventricular volumes were measured with VOCAL and sonoAVC. The stroke volume was calculated from these measurements. Reliability and agreement of the two techniques were evaluated with intraclass correlation coefficients (ICCs), and proportionate Bland-Altman plots were constructed. The time necessary to complete the measurements with either technique was compared. Intraobserver and interobserver agreement of measurements was calculated. All data sets could be measured with both techniques. A high degree of reliability was observed between VOCAL and sonoAVC (left ventricular stroke volume ICC, 0.978; 95% confidence interval [CI], 0.957-0.989; right ventricular stroke volume ICC, 0.985; 95% CI, 0.972-0.992). The time necessary to measure the stroke volume was significantly shorter with sonoAVC (2.8 versus 11.7 minutes; P < .0001) than with VOCAL. Bland-Altman tests showed no clinically significant mean percent differences between stroke volume measurements obtained from each ventricle by the same observer or by 2 independent observers using either VOCAL or sonoAVC. There was good agreement between cardiac volumes measured with VOCAL and sonoAVC. Sonographic automatic volume calculation represents a rapid technique for estimating fetal stroke volume and promises to become the method of choice.

Assessment of the accuracy and reproducibility of right ventricular volume measurements in patients with congenital heart disease

Methods Data from 24 patients (mean age 19 years; range: 0.2 to 51 years) with CHD who underwent CMR were reviewed. Patients with ventricular level shunts and more than mild tricuspid regurgitation were excluded. Cine steady state free precession imaging was acquired in stacked axial and short-axis slices. RV contours were traced manually. Argus software was used to compute the end systolic volume (ESV) and end diastolic volume (EDV) using Simpson's method, and stroke volume (SV) by subtracting ESV from EDV. RV SV was also measured directly by phase contrast (PC) imaging, acquired in the main pulmonary artery. Flow measurements were made using Argus software. Measurements were made twice by one skilled observer to assess intra-observer variability. A second skilled observer repeated these measurements in a blinded fashion to assess inter-observer variability. Agreement between PC SV and SV measured in the axial and short-axis planes was assessed using Lin's concordance correlation coefficient (CCC). Interand intra-observer variability was also assessed using Lin's CCC.

La anestesia subaracnoidea (espinal) podría disminuir la función ventricular izquierda: Estudio con ecocardiografía transtorácica intraoperatoria

Spinal anesthesia reduces arterial blood pressure mainly because of vasodilation secondary to blocking preganglionic fibers in the sympathetic nervous system. It is hypothesized, however, that spinal anesthesia may also be a direct cause of some degree of myocardial depression. These factors may be studied by means of transthoracic echocardiography to detect changes in left ventricular function following start of spinal anesthesia. Left ventricular function was assessed in ASA 1 patients before spinal anesthesia, by means of measurements of left ventricular systolic and diastolic volumes, ejection fraction, the Doppler transmitral (E and A) and tissue (E', A', and Sm) inflow velocities, and the left ventricular outflow tract velocity. The measurements were repeated after the start of spinal anesthesia. Fifty-five patients (58% men; mean [SD] age, 46.9 [15.7] years) were studied. The spinal block caused a significant reduction in systolic and diastolic arterial blood pressures (P < .0009). Diastolic function also decreased (the E wave from 69.52 [11.24] to 61.59 [10.82] cm x s(-1) and the A wave from 50.18 [10.69] to 43.67 [13.75] cm x s(-1); P < .0001). Also reduced was the left ventricular outflow tract velocity, from 18.77 (4.89) to 15.64 (4.75) cm x s(-1) (P < .00001). There were no significant changes in systolic and diastolic volumes or ejection fraction. There was no correlation between the level of spinal block and the magnitude of changes. Left ventricular function was compromised after spinal anesthesia without significant changes in left ventricular volumes. We can infer that the reduction in arterial blood pressure after a spinal block might be due to some degree of direct ventricular depression.

Prenatal diagnosis of cardiac defect

Fetal cardiac malformations are the most common congenital malformations with an incidence of 8:1000 among live births. Furthermore, 10% of neonatal deaths and up to 50% of infant deaths were attributed to congenital anomalies. In 2006 the International Society of Ultrasound in Obstetrics and Gynecology (ISUOG) published practice guidelines for the sonographic screening of congenital heart disease (CHD) at some time between 18 and 22 weeks’ gestation. Two levels for screening low-risk fetuses for heart anomalies are recommended. Firstly, a basic scan should be performed by analyzing a four-chamber view of the fetal heart. Secondly, an extended-basic scan further examines the size and relationships of both arterial outflow tracts. Obstetricians, midwives, and perinatalogists are able to evaluate a thorough examination of the four-chamber view, both arterial outflow tracts, three vessels and trachea view, and an assessment of pulmonary venous return. These anatomical features are usually evaluated using transverse views, although sagittal scanning planes are also used as necessary. Color doppler ultrasonography is an important component of the fetal echocardiogram. Occasionally, advanced techniques such as Velocity Vector Imaging (VVI) may be required to evaluate fetal cardiac function using measurements of ventricular ejection fraction, stroke volume, and ventricular strain parameters. An accurate prenatal diagnosis of cardiac defects, especially ductal dependent anomaly, is extremely important for healthcare professionals who will be counseling parents about the nature, severity, clinical management and prognosis of their unborn child. Fetal cardiac malformations are the most common congenital malformations with an incidence of 8 : 1000 among live births. Furthermore, 10% of neonatal deaths and up to 50% of infant deaths were attributed to congenital anomalies. Fetal echocardiography has now become widely used in obstetrics and perinatology. It allows detailed prenatal diagnosis of suspected or known congenital heart disease and serves as a general screening tool for possible congenital heart disease. Outcomes of infants with severe cardiac malformations can improve with prenatal diagnosis of congenital heart disease. Fetal echocardiography also allows improvement s of counseling the families after a prenatal diagnosis of congenital heart defects. It allows them to better anticipate the expected course of the fetal life and leads to a better understanding of the postnatal prognosis. The physician and the family may have enough time to plan the timing, mode and site of delivery to perform surgery on the neonate in the best possible hemodynamic conditions, thus improving the surgical outcome. 1

Right ventricular remodelling after pulmonary thrombendarterectomie (PEA) for chronic thrombembolic pulmonary hypertension by cardiac MRI

Introduction About 5% of all patients suffering acute pulmonary embolism will develop chronic thrombembolic pulmonary hypertension (CTEPH). This in turn causes continuous detoriation of right ventricular function. Pulmonary thrombendarterectomy (PEA) is a possible cure of this condition with favourable long term prognosis. Cardiac magnetic resonance imaging (cMRI) is an excellent tool for measurement of right ventricular volumes and function.

Comparison of Echocardiographic and Cardiac Magnetic Resonance Imaging Measurements of Functional Single Ventricular Volumes, Mass, and Ejection Fraction (from the Pediatric Heart Network Fontan Cross-Sectional Study)

Comparison of Echocardiographic and Cardiac Magnetic Resonance Imaging Measurements of Functional Single Ventricular Volumes, Mass, and Ejection Fraction (from the Pediatric Heart Network Fontan Cross-Sectional Study)

2009 Laennec Clinician/Educator Lecture—Diastolic Function: Past, Present, and Future

One hundred years ago, research by Otto Frank, Carl Wiggers, and Yandell Henderson identified cardiac tonus and variable diastolic relaxation as important aspects of cardiac function. Belief in the existence of cardiac tonus and variable relaxation then went into eclipse from 1930 to 1970, during which time the application of A.V. Hill’s equations of muscle mechanics (derived from experiments on skeletal muscle) to cardiac physiology assumed that cardiac muscle was basically a “twitch” muscle and was completely passive between contractions. For the past 40 years, there has been a resurgence of interest in and experimental support for the concept of variable diastolic relaxation. At the same time, improved clinical measurement techniques have allowed simultaneous measurement of left ventricular pressure and volume, establishing firmly the existence and importance of rapidly occurring shifts in the diastolic left ventricular pressure–volume relation. Today, it is clear that up to 50% of patients presenting with acute heart failure manifest as pulmonary edema are exhibiting increased resistance to diastolic left ventricular filling as their primary problem, rather than impaired contractile function and reduced left ventricular systolic emptying. Many causes of increased resistance to diastolic left ventricular filling occur clinically, including myocardial hypertrophy, ischemia, diabetes, and increased coronary venous pressure, and may be modifiable with appropriate therapy. Examples will be presented.

Measurement of physical work capacity in patients with chronic aortic regurgitation: a potential improvement in patient management

Timing of surgery in aortic regurgitation (AR) is important. Exercise testing is recommended upon uncertainty about functional limitations but reports on cardiopulmonary exercise testing (CPET) in populations with pure chronic AR are scarce. Twenty-eight patients referred for surgery because of chronic AR (13 in NYHA I, 10 in NYHA II and five in NYHA III) were tested by CPET pre- and 6 months postoperatively. Echocardiography, with measurement of left ventricular ejection fraction (LVEF), diameters (LVED, LVES) and volumes (LVEDV, LVESV) was also performed. The patients had normal LVEF pre- and postoperatively. LV diameters and volumes diminished significantly postoperatively (LVED from 67 to 57, LVES from 49 to 41 mm; P < 0.001). The majority of the patients had a 'low' physical work capacity, none of them performed better than 'average' according to Astrand's classification preoperatively and there was no significant postoperative improvement. The mean peak oxygen uptake (VO(2peak)) was 25 ml kg(-1) min(-1) both pre- and postoperatively, and six of the 28 patients had a VO(2peak) of less than 20 ml kg(-1) min(-1). VO(2peak) was not significantly related to NYHA class. LVEF, diameters and volumes at rest did not fulfil the criteria for surgery in most of our AR patients, of whom 46% were asymptomatic. However, many had a remarkably low work capacity, which was neither improved 6 months postoperatively nor correlated to echocardiographic LV dimensions. CPET predicted the postoperative work capacity and may, therefore, be a useful complement for timing of surgery in patients with chronic AR.

Three-dimensional cine MRI in free-breathing infants and children with congenital heart disease

Patients with congenital heart disease frequently have complex cardiac and vascular malformations requiring detailed non-invasive diagnostic evaluation including functional parameters. To evaluate the morphological and functional information provided by a novel 3-D cine steady-state free-precession (SSFP) sequence. Twenty consecutive children (mean age 2.2 years, nine boys) were examined using a 1.5-T MR system including 2-D cine gradient-recalled-echo sequences, static 3-D SSFP and 3-D cine SSFP sequences. Measurement of ventricular structures and volumes showed close agreement between the 3-D cine SSFP sequence and the 2-D cine gradient-recalled-echo and static 3-D SSFP sequences (left ventricular volumes mean difference 1.0-1.9 ml and 8.8-11.4%, respectively; right ventricular volumes 1.7-2.1 ml and 9.9-16.9%, respectively). No systematic bias was observed. 3-D cine MRI provides anatomic as well as functional information with sufficient spatial and temporal resolution in free-breathing infants with congenital heart disease.

Conductance, admittance, and hypertonic saline: should we take ventricular volume measurements with a grain of salt?

undoubtedly the most comprehensive way to assess contractile function of the heart relies on pressure-volume relationships, often called pressure-volume loops. Originally established in the canine model by Sagawa and coworkers, pressure-volume relationships allow us to determine indexes of

Determination of right ventricular end systole by cardiovascular magnetic resonance imaging: a standard method of selection

For reproducible measurements of right ventricular (RV) volume and function, it may be important to use a consistent method to identify end systole (ES). We determined whether a significant difference exists between RV volumes measured using varying criteria from previous studies to define the timing of ES. In three normal subjects and nine patients with congenital heart disease, we measured RV volume from 3D reconstructions generated from 12 short and long axis magnetic resonance images (MRI). Cine frames analyzed included two frames before and three frames following ES, which we determined as the frame in which chamber area was most frequently minimum. ES coincided with onset of aortic valve closure in ten of 12 subjects; complete closure occurred 1 frame later. The tricuspid valve began to open 1-2 frames after ES, and completely opened 2-4 frames after ES. RV volume was unchanged between ES and the frame following. However, ES volume differed significantly from volume measured 1 or 2 frames before ES and from volume measured 2 or 3 frames following ES, although these volume differences lay within the range of observer variability. The time of minimum RV area in the 4-chamber view agreed closely with that of ES (intraclass correlation coefficient = 0.962). We conclude that minimum RV area in the 4-chamber view is a convenient marker of use for ES, and that aortic valve closure or onset of tricuspid valve opening could also be used, being unlikely to result in clinically significant errors.

The use of real-time three-dimensional echocardiography for the quantification of left ventricular volumes and function

The purpose of this review is to provide readers with an update on the latest developments and the current status of the real-time three-dimensional echocardiographic (RT3DE) quantitative evaluation of left ventricular volumes and function. In recent years, the growing availability of RT3DE imaging technology, its ease of use and its multiple attractive features have sparked significant interest in the echocardiography community, resulting in a large number of research papers, most of which have endorsed RT3DE imaging for clinical use by demonstrating its unique capabilities in different scenarios. In parallel, the clinical acceptance of this new tool has broadened significantly. Although the clinical value of RT3DE evaluation of the left ventricle is already well established, future improvements will determine whether this methodology can become the new standard reference technique for accurate and repeatable measurement of left ventricular volumes, mass, regional left ventricular function and dyssynchrony.

Dynamic correction for parallel conductance, GP, and gain factor, α, in invasive murine left ventricular volume measurements

The conductance catheter technique could be improved by determining instantaneous parallel conductance (G(P)), which is known to be time varying, and by including a time-varying calibration factor in Baan's equation [alpha(t)]. We have recently proposed solutions to the problems of both time-varying G(P) and time-varying alpha, which we term "admittance" and "Wei's equation," respectively. We validate both our solutions in mice, compared with the currently accepted methods of hypertonic saline (HS) to determine G(P) and Baan's equation calibrated with both stroke volume (SV) and cuvette. We performed simultaneous echocardiography in closed-chest mice (n = 8) as a reference for left ventricular (LV) volume and demonstrate that an off-center position for the miniaturized pressure-volume (PV) catheter in the LV generates end-systolic and diastolic volumes calculated by admittance with less error (P < 0.03) (-2.49 +/- 15.33 microl error) compared with those same parameters calculated by SV calibrated conductance (35.89 +/- 73.22 microl error) and by cuvette calibrated conductance (-7.53 +/- 16.23 microl ES and -29.10 +/- 31.53 microl ED error). To utilize the admittance approach, myocardial permittivity (epsilon(m)) and conductivity (sigma(m)) were calculated in additional mice (n = 7), and those results are used in this calculation. In aortic banded mice (n = 6), increased myocardial permittivity was measured (11,844 +/- 2,700 control, 21,267 +/- 8,005 banded, P < 0.05), demonstrating that muscle properties vary with disease state. Volume error calculated with respect to echo did not significantly change in aortic banded mice (6.74 +/- 13.06 microl, P = not significant). Increased inotropy in response to intravenous dobutamine was detected with greater sensitivity with the admittance technique compared with traditional conductance [4.9 +/- 1.4 to 12.5 +/- 6.6 mmHg/microl Wei's equation (P < 0.05), 3.3 +/- 1.2 to 8.8 +/- 5.1 mmHg/microl using Baan's equation (P = not significant)]. New theory and method for instantaneous G(P) removal, as well as application of Wei's equation, are presented and validated in vivo in mice. We conclude that, for closed-chest mice, admittance (dynamic G(P)) and Wei's equation (dynamic alpha) provide more accurate volumes than traditional conductance, are more sensitive to inotropic changes, eliminate the need for hypertonic saline, and can be accurately extended to aortic banded mice.

Electrical Conductivity and Permittivity of Murine Myocardium

A classic problem in traditional conductance measurement of left ventricular (LV) volume is the separation of the contributions of myocardium from blood. Measurement of both the magnitude and the phase of admittance allow estimation of the time-varying myocardial contribution, which provides a substantial improvement by eliminating the need for hypertonic saline injection. We present in vivo epicardial surface probe measurements of electrical properties in murine myocardium using two different techniques (a digital and an analog approach). These methods exploit the capacitive properties of the myocardium, and both methods yield similar results. The relative permittivity varies from approximately 100,000 at 2 kHz to approximately 5000 at 50 kHz. The electrical conductivity is approximately constant at 0.16 S/m over the same frequency range. These values can be used to estimate and eliminate the time-varying myocardial contribution from the combined signal obtained in LV conductance catheter measurements, thus yielding the blood contribution alone. To study the effects of albumin on the blood conductivity, we also present electrical conductivity estimates of murine blood with and without typical administrations of albumin during the experiment. The blood conductivity is significantly altered (p < 0.0001) by administering albumin (0.941 S/m with albumin, 0.478 S/m without albumin).

Serial Assessment of Ventricular Morphology and Function

Cardiovascular magnetic resonance (CMR) is an accurate, reproducible and well-validated imaging technique for the measurement of left ventricular and right ventricular volumes, function, and mass. In patients who have heart failure, CMR is ideally suited both for the initial assessment of fundamental parameters of cardiac function and longitudinal follow-up. Because of its accuracy, the decision to implement therapeutic measures based on cutoff values for ventricular ejection fraction can be made with confidence. Because the above-mentioned parameters correlate with morbidity and mortality, CMR can be used to estimate the prognosis of an individual patient and to obtain surrogate parameters in clinical trials. The process of ventricular remodeling after cardiac injury and reverse remodeling using medical and interventional therapy can be assessed using relatively small sample sizes, which puts CMR in the forefront of imaging techniques in remodeling research.