Thoracic aorta 3D hemodynamics in pediatric and young adult patients with bicuspid aortic valve

BACKGROUND

To evaluate the 3D hemodynamics in the thoracic aorta of pediatric and young adult bicuspid aortic valve (BAV) patients.

METHODS

4D flow MRI was performed in 30 pediatric and young adult BAV patients (age: 13.9 ± 4.4 (range: [3.4, 20.7]) years old, M:F = 17:13) as part of this Institutional Review Board-approved study. Nomogram-based aortic root Z-scores were calculated to assess aortic dilatation and degree of aortic stenosis (AS) severity was assessed on MRI. Data analysis included calculation of time-averaged systolic 3D wall shear stress (WSSsys ) along the entire aorta wall, and regional quantification of maximum and mean WSSsys and peak systolic velocity (velsys ) in the ascending aorta (AAo), arch, and descending aorta (DAo). The 4D flow MRI AAo velsys was also compared with echocardiography peak velocity measurements.

RESULTS

There was a positive correlation with both mean and max AAo WSSsys and peak AAo velsys (mean: r = 0.84, P < 0.001, max: r = 0.94, P < 0.001) and AS (mean: rS  = 0.43, P = 0.02, max: rS  = 0.70, P < 0.001). AAo peak velocity was significantly higher when measured with echo compared with 4D flow MRI (2.1 ± 0.98 m/s versus 1.27 ± 0.49 m/s, P < 0.001).

CONCLUSION

In pediatric and young adult patients with BAV, AS and peak ascending aorta velocity are associated with increased AAo WSS, while aortic dilation, age, and body surface area do not significantly impact AAo hemodynamics. Prospective studies are required to establish the role of WSS as a risk-stratification tool in these patients.

Three-dimensional haemodynamics in patients with obstructive and non-obstructive hypertrophic cardiomyopathy assessed by cardiac magnetic resonance

AIMS

The left ventricular outflow tract (LVOT) peak pressure gradient is an important haemodynamic descriptor in patients with hypertrophic cardiomyopathy (HCM); however, secondary alterations in aortic blood flow have not been well described in these patients. Aortic flow derangement is not easily assessed by traditional imaging methods, but may provide unique characterization of this disease. In this study, we demonstrated how four-dimensional (4D) flow MRI can assess LVOT peak pressure gradients in HCM patients and also evaluated the ascending aorta (AAo) haemodynamic derangement associated with HCM.

METHODS AND RESULTS

Obstructive (n = 12) and non-obstructive (n = 18) HCM patients were included in the study along with 10 normal volunteers. 4D flow MRI was used to visualize three-dimensional (3D) blood flow patterns within the LVOT and AAo, which were graded for the presence of helical flow as a marker of flow derangement (absent = 0, mild/moderate = 1, and severe = 2). MRI-estimated pressure gradient (ΔPMRI) was calculated from the peak systolic 3D blood velocity profile within the LVOT. There was higher grade helical flow in obstructive HCM patients compared with non-obstructive patients (P = 0.04) and volunteers (P < 0.001). Non-obstructive patients also had higher helix grade than volunteers (P = 0.002). There was a significant correlation between helical grade and increasing ΔPMRI (rS = 0.69, P < 0.001). Systolic anterior motion (SAM) of the mitral valve was associated with both increasing helix grade (P < 0.001) and ΔPMRI (P = 0.006).

CONCLUSIONS

Ascending aorta flow derangement occurs in both obstructive and non-obstructive HCM patients and can be identified using 4D flow MRI. The degree of flow derangement correlates with LVOT gradient, SAM, and outflow tract geometry.

4D flow imaging with MRI

Magnetic resonance imaging (MRI) has become an important tool for the clinical evaluation of patients with cardiovascular disease. Since its introduction in the late 1980s, 2-dimensional phase contrast MRI (2D PC-MRI) has become a routine part of standard-of-care cardiac MRI for the assessment of regional blood flow in the heart and great vessels. More recently, time-resolved PC-MRI with velocity encoding along all three flow directions and three-dimensional (3D) anatomic coverage (also termed '4D flow MRI') has been developed and applied for the evaluation of cardiovascular hemodynamics in multiple regions of the human body. 4D flow MRI allows for the comprehensive evaluation of complex blood flow patterns by 3D blood flow visualization and flexible retrospective quantification of flow parameters. Recent technical developments, including the utilization of advanced parallel imaging techniques such as k-t GRAPPA, have resulted in reasonable overall scan times, e.g., 8-12 minutes for 4D flow MRI of the aorta and 10-20 minutes for whole heart coverage. As a result, the application of 4D flow MRI in a clinical setting has become more feasible, as documented by an increased number of recent reports on the utility of the technique for the assessment of cardiac and vascular hemodynamics in patient studies. A number of studies have demonstrated the potential of 4D flow MRI to provide an improved assessment of hemodynamics which might aid in the diagnosis and therapeutic management of cardiovascular diseases. The purpose of this review is to describe the methods used for 4D flow MRI acquisition, post-processing and data analysis. In addition, the article provides an overview of the clinical applications of 4D flow MRI and includes a review of applications in the heart, thoracic aorta and hepatic system.

A methodology to detect abnormal relative wall shear stress on the full surface of the thoracic aorta using four-dimensional flow MRI

PURPOSE

To compute cohort-averaged wall shear stress (WSS) maps in the thoracic aorta of patients with aortic dilatation or valvular stenosis and to detect abnormal regional WSS.

METHODS

Systolic WSS vectors, estimated from four-dimensional flow MRI data, were calculated along the thoracic aorta lumen in 10 controls, 10 patients with dilated aortas, and 10 patients with aortic valve stenosis. Three-dimensional segmentations of each aorta were coregistered by group and used to create a cohort-specific aortic geometry. The WSS vectors of each subject were interpolated onto the corresponding cohort-specific geometry to create cohort-averaged WSS maps. A Wilcoxon rank sum test was used to generate aortic P-value maps (P<0.05) representing regional relative WSS differences between groups.

RESULTS

Cohort-averaged systolic WSS maps and P-value maps were successfully created for all cohorts and comparisons. The dilation cohort showed significantly lower WSS on 7% of the ascending aorta surface, whereas the stenosis cohort showed significantly higher WSS on 34% of the ascending aorta surface.

CONCLUSIONS

The findings of this study demonstrated the feasibility of generating cohort-averaged WSS maps for the visualization and identification of regionally altered WSS in the presence of disease, compared with healthy controls.

Influence of documented history of coronary artery disease on outcomes in patients admitted for worsening heart failure with reduced ejection fraction in the EVEREST trial

AIMS

Data on the prognosis of heart failure (HF) patients with coronary artery disease (CAD) have been conflicting. We describe the clinical characteristics and mode-specific outcomes of HF patients with reduced ejection fraction (EF) and documented CAD in a large randomized trial.

METHODS AND RESULTS

EVEREST was a prospective, randomized trial of vasopressin-2 receptor blockade, in addition to standard therapy, in 4133 patients hospitalized with worsening HF and reduced EF. Patients were classified as having CAD based on patient-reported myocardial infarction (MI) or coronary revascularization. We analysed the characteristics and outcomes [all-cause mortality and cardiovascular (CV) mortality/HF hospitalization] of patients with and without documented CAD. All events were centrally adjudicated. Documented CAD was present in 2353 patients (57%). Patients with CAD were older and had more co-morbidities compared with those without CAD. Patients with CAD were more likely to receive a beta-blocker, but less likely to receive an angiotensin-converting enzyme (ACE) inhibitor or aldosterone antagonist (P < 0.01). After risk adjustment, patients with documented CAD had similar mortality [hazard ratio (HR) 1.12, 95% confidence interval (CI) 0.97-1.30], but were at an increased risk for CV mortality/HF hospitalization (HR 1.25, 95% CI 1.12-1.41) due to an increased risk for HF hospitalization (HR 1.26, 95% CI 1.10-1.44). Patients with CAD had increased HF- and MI-related events, but similar rates of sudden cardiac death.

CONCLUSION

Documented CAD in patients hospitalized for worsening HF with reduced EF was associated with a higher burden of co-morbidities, lower use of HF therapies (except beta-blockers), and increased HF hospitalization, while all-cause mortality was similar.

Evidence from Western north america for rapid shifts in climate during the last glacial maximum

The Estancia basin in southwestern United States contains evidence for strong and rapid pulsations in the supply of moisture brought into the region during the last ice age. The pulses were recorded during episodes of stream discharge that spread plumes of fresh water laden with quartz sand over the saline lake. The largest pulses in stream discharge lasted only a few decades, were organized into cycles that were spaced approximately 200 to 250 and 2000 years apart, and were of sufficient magnitude to freshen and maintain the lake at its maximum recorded elevation.

The cost of infertility evaluation and therapy: findings of a self-insured university healthcare plan

OBJECTIVE

To assess the total costs of infertility coverage, determine the proportion of healthcare costs related to infertility, compare infertility costs to those of other diseases, and calculate a per member per month cost of an infertility benefit.

DESIGN

Historical prospective analysis.

SETTING

A university-based, self-insured, fee-for-service healthcare plan.

PATIENT(S)

Healthcare policy members from January 1993 through December 1995.

INTERVENTION(S)

General and infertility-specific healthcare that included diagnostic tests for infertility, induction of ovulation, artificial insemination, donor gametes, in vitro fertilization, gamete intrafallopian transfer, zygote intrafallopian transfer, microsurgical epididymal sperm aspiration, embryo cryopreservation, and frozen embryo transfer.

MAIN OUTCOME MEASURE(S)

Healthcare costs, as calculated from the International Classification of Diseases, Volume 9 codes.

RESULT(S)

Total healthcare and infertility-specific costs of the university healthcare plan over a 3-year period were $86,445,642 and $680,921, respectively. Therefore, infertility accounted for 0.79% of the total university healthcare costs. The mean total and infertility-specific per member per month healthcare costs were $86.15 and $0.67, respectively.

CONCLUSION(S)

These data reveal that infertility costs account for only a small fraction of the total healthcare costs and can be attained at a nominal monthly fee.

Cost-effective treatment of the infertile couple

OBJECTIVE

To review the published literature on the cost-effective approach to infertility treatment.

DESIGN

The literature on the economics and cost-effectiveness of infertility treatments was reviewed. Studies related to this topic were identified through MEDLINE.

RESULT(S)

Few cost-effectiveness studies about infertility treatment have been published. In the absence of tubal blockage and severe male factor, use of IUI and hMG-IUI is more cost-effective than IVF. In vitro fertilization is at least as cost-effective as tubal surgery. Although IVF costs are high, they fall well within the range of other accepted medical treatments and are below the general public's willingness to pay for these treatments.

CONCLUSION(S)

Cost-effectiveness analysis is an important means of improving quality of care while controlling costs. Further work regarding cost-effectiveness of treatments among different diagnostic groups is needed.

Cost-effectiveness of infertility treatments: a cohort study

OBJECTIVE

To determine the cost-effectiveness of infertility treatments.

DESIGN

Retrospective cohort study.

SETTING

Academic medical center infertility practice.

PATIENT(S)

All patients treated for infertility in a 1-year time span.

INTERVENTION(S)

Intrauterine inseminations, clomiphene citrate and IUI (CC-IUI), hMG and IUI (hMG-IUI), assisted reproductive techniques (ART), and neosalpingostomy by laparotomy.

MAIN OUTCOME MEASURE(S)

All medical charges and pregnancy outcomes associated with the treatments were obtained. Cost-effectiveness ratios defined as cost per delivery were determined for each procedure. The effects of a woman's age and the number of spermatozoa inseminated on cost-effectiveness of the procedures was also determined.

RESULT(S)

Intrauterine inseminations, CC-IUI, and hMG-IUI have a similar cost per delivery of between $7,800 and $10,300. All of these were more cost-effective than ART, which had a cost per delivery of $37,000. Assisted reproductive techniques in women with blocked fallopian tubes was more cost-effective than tubal surgery performed by laparotomy, which had a cost per delivery of $76,000. Increasing age in women and lower numbers of spermatozoa inseminated were factors leading to higher costs per delivery for IUI, CC-IUI, hMG-IUI, and ART. Use of donor oocytes reduced the cost per delivery of older women to the range seen in younger women with ART.

CONCLUSION(S)

Our analysis supports, in general, the use of IUI, CC-IUI, and hMG-IUI before ART in women with open fallopian tubes. For women with blocked fallopian tubes, IVF-ET appears to be the best treatment from a cost-effectiveness standpoint.

The efficacy and cost effectiveness of embryo cryopreservation compared with other assisted reproductive techniques

OBJECTIVE

To evaluate the efficacy and cost effectiveness of embryo cryopreservation compared with other assisted reproductive techniques (ARTs).

DESIGN

Retrospective review of medical records and health care costs.

SETTING

Tertiary care academic medical school ART program.

PATIENTS

For determination of the efficacy of cryopreserved ET, we analyzed 610 patients undergoing the first 1,000 oocyte retrievals in our program. For determination of cost effectiveness, we analyzed the costs associated with 334 initiated ART cycles in 1992.

MAIN OUTCOME MEASURES

The ongoing pregnancy rate (PR) per initiated cycle and per oocyte retrieval. The medical costs associated with each procedure.

RESULTS

The transfer of cryopreserved embryos increased the ongoing PR per oocyte retrieval by 6.6%. Transfer of cryopreserved embryos was cost effective compared with other ARTs. The cost per delivery for cryopreserved ETs was between 25% and 45% that of a fresh cycle.

CONCLUSIONS

Including embryo cryopreservation in an ART program can improve PRs and lower the ultimate cost per delivery.

A correlative study of RU38486 biopotency and competition with [3H]dexamethasone for receptors in the rat central nervous system

Dexamethasone inhibitory action on the release of adrenocorticotrophin has been studied using in vitro anterior pituitary preparations. This inhibition is reversed when the animal is given the antiglucocorticoid compound RU38486 simultaneously with dexamethasone. RU38486 acts at the receptor level and in the cytosolic binding study, it competes with [3H]dexamethasone for the binding sites in pituitary. Such competition is even more pronounced in hypothalamus and hippocampus, indicating that RU38486 also exert its antagonistic action at these sites.