Coronary haemodynamics associated with left ventricular hypertrophy in aortic stenosis and hypertension

Background

Left ventricular hypertrophy (LVH) occurs in both aortic stenosis (AS) and hypertension (HT) due to an increase in afterload. However, in AS there is an increase in resting coronary flow (per gram of LV) while in HT it is reduced.

Wave intensity analysis (WIA) is a well-established method of characterising and quantifying the energies that drive coronary flow. Energies propagating from the proximal vessel (aorta and systemic arteries) interact with energies travelling from the distal end (myocardial microcirculation). WIA allows the separation of these energies into the waves that drive cyclic changes in coronary flow.

Purpose

We aimed to compare coronary flow patterns in LVH secondary to AS with coronary flow patterns in LVH secondary to HT.

Methods

Thirty-one participants were recruited (mean age 63, 18 female), 10 with LVH and severe AS, 11 with LVH and HT, and 10 with no LVH and no AS. Participants underwent invasive pressure and Doppler velocity measurements in each of the left coronary arteries and echocardiography. We applied WIA.

Results

Mean resting coronary flow per gram of LV tissue (Fig. 1) was increased in participants with LVH secondary to AS (1.62±0.60 ml/min/g) and reduced in participants with LVH secondary to HT (0.49±0.27 ml/min/g), compared to participants with no LVH and no AS (1.47±0.73 ml/min/g).

We observed marked differences between the magnitudes of the waves driving coronary flow in the three groups (Fig. 2). Forward and backward travelling waves are shown above and below the line respectively. Waves causing acceleration of coronary forward flow are shown as black and waves causing deceleration are shown in white.

Wave 6, the backwards decompression wave (BDW), is particularly important for myocardial perfusion. The BDW corresponds to the diastolic 'suction' of blood down the coronary arteries during myocardial relaxation.

The energy of the BDW was increased in LVH secondary to AS (31.1x103 W m–2 s–2) but was reduced in LVH secondary to HT (12.3x103 W m–2 s–2) (p<0.05), compared to participants with no LVH and no AS (14.3x103 W m–2 s–2).

The energy of the BDW correlated with LV cavity pressure (r=0.84, p<0.001) and diastolic time (r=−0.62, p<0.001) only in LVH secondary to AS participants. In contrast, the BDW correlated with LV mass (r=−0.49, p=0.03) in participants with LVH secondary to HT and with no LVH and no AS, but not in participants with LVH secondary to AS.

Conclusions

In hypertension, LVH is associated with reduced mean coronary flow and reduced myocardial “suction” during diastole, presumably by the reduction in myocardial compliance associated with diastolic dysfunction.

However, in AS the large pressure gradient between the LV cavity and the aorta results in a large contractile force which is generated in systole and then released in diastole. This large diastolic force overwhelms any local impairment caused by the hypertrophied myocardium and contributes to high resting coronary flow in AS.

Funding Acknowledgement

Type of funding sources: None.

An experimental evaluation of the benefits and costs of providing fertility information to adolescents and emerging adults

STUDY QUESTION

Does the provision of fertility (compared to control) information affect fertility-related knowledge, perceived threat of infertility, anxiety, physical stress and fertility plans in adolescents and emerging adults?

SUMMARY ANSWER

The provision of fertility information was associated with increased fertility knowledge (emerging adults) and greater infertility threat (adolescents and emerging adults).

WHAT IS KNOWN ALREADY

According to fertility education research, adolescents and emerging adults know less than they should know about fertility topics. Fertility knowledge can be improved through the provision of information in older adults.

STUDY DESIGN, SIZE, DURATION

Experimental design. Secondary and university students completed pre-information questionnaires, were randomly assigned via computer to an experimental group, read either fertility (FertiEduc group) or healthy pregnancy information (Control group), and completed post-information questionnaires. Data were collected in group sessions via an online portal.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Eligible participants were aged 16–18 (adolescents) or 21–24 years (emerging adults), childless, not currently pregnant (for men, partner not pregnant) or trying to conceive, presumed fertile and intending to have a child in the future. Of the 255 invited, 208 (n = 93 adolescents, n = 115 emerging adults) participated. The FertiEduc group received ‘A Guide to Fertility’, four online pages of information about fertility topics (e.g. ‘When are men and women most fertile?’) and the Control group received four online pages from the National Health Service (NHS) pregnancy booklet ‘Baby Bump and Beyond’. Participants completed a questionnaire (fertility knowledge, perceived threat of infertility, anxiety, physical stress and fertility plans, moderators) prior to and after the provision of information. Mixed factorial analysis of variance was used to examine the effects of information provision and hierarchical multiple regression to assess potential moderators of knowledge.

MAIN RESULTS AND THE ROLE OF CHANCE

The FertiEduc and Control groups were equivalent on age, gender, disability, relationship status and orientation at baseline. Results showed that fertility information significantly increased fertility knowledge for emerging adults only (P < 0.001) and threat of infertility for emerging adults and adolescents (P = 0.05). The moderators were not significant. Participation in the study was associated with an increase in feelings of anxiety but a decrease in physical stress reactions. Adolescents had more optimal fertility plans compared to emerging adults due to being younger.

LIMITATIONS, REASONS FOR CAUTION

This was an experimental study on a self-selected sample of men and women from selected educational institutions and only short term effects of information were studied.

WIDER IMPLICATIONS OF THE FINDINGS

Provision of fertility information can have benefits (increased fertility knowledge) but also costs (increase potential threat of infertility). Adolescents find fertility information positive but do not learn from it. Fertility education should be tailored according to age groups and created to minimise negative effects. Longitudinal examination of the effects of fertility information in multi-centre studies is warranted and should include measures of perceived threat of infertility.

STUDY FUNDING/COMPETING INTEREST(S)

Cardiff University funded this research. All authors have no conflicts of interest to declare.

New Transcranial Doppler (TCD) Waveform Shape Parameters: A Repeatability/Reproducibility Study

Introduction and Objective

Doppler ultrasound is used in nearly every medical discipline for the evaluation of blood flow. The cerebral circulation is of particular interest, but is difficult to interpret because of the complex hemodynamics of the brain's blood flow. However, advances in the field of transcranial Doppler (TCD) could have important clinical and cost-saving benefits. We describe the testing of a novel method for acquiring and analyzing TCD flow velocity waveforms, in conjunction with other physiologic data. We also evaluate the repeatability and reproducibility of the technique.

Methods

We used custom-designed waveform analysis software to calculate 16 new waveform shape parameters and indices. We present the repeatability and reproducibility results for the new waveform shape parameters, as well as traditional TCD measurements, during repeated vasomotor reactivity studies on five healthy subjects. A ranked score ( mean value of test 1 and 2/coefficient of repeatability) is used to evaluate each parameter. The scores are presented by category: Traditional TCD Measurements, Velocity Minima, Velocity Maxima, Acceleration/Deceleration, Miscellaneous measures (e.g. blood pressure, heart rate), Time Measurements, and Shape Indices. Higher scores indicate better reproducibility.

Results

The mean scores of all parameters for each testing segment were Baseline 4.60, Hypercapnia 4.34, and Hypocapnia 4.00; showing that Baseline measurements are more easily reproduced than measurements during an intervention, particularly Hypocapnia. Individual parameters with the best reproducibility over all three testing segments are: RI (Resistance Index) 19.02; Mean Resistance ( mean blood pressure/mean velocity) 10.64; Umin (end-diastolic velocity) 9.84; Umaxdias (velocity rise immediately after aortic valve closure) 9.83; and DuDtmax (systolic acceleration) 8.54. We discuss why some parameters are more reliable than others in TCD studies and how the cyclical variations in the cerebral circulation can affect reproducibility.

Conclusions

This new methodology allows for discrete measurements of Doppler waveforms and would have the ability to track subtle changes during physiological or pharmacological interventions. These advances may aid the interpretation of complex cerebral hemodynamics, and increase the utility of this non-invasive, low-cost technique.

An ovine hepatorenal fibrocystic model of a Meckel-like syndrome associated with dysmorphic primary cilia and TMEM67 mutations

Meckel syndrome (MKS) is an inherited autosomal recessive hepatorenal fibrocystic syndrome, caused by mutations in TMEM67, characterized by occipital encephalocoele, renal cysts, hepatic fibrosis, and polydactyly. Here we describe an ovine model of MKS, with kidney and liver abnormalities, without polydactyly or occipital encephalocoele. Homozygous missense p.(Ile681Asn; Ile687Ser) mutations identified in ovine TMEM67 were pathogenic in zebrafish phenotype rescue assays. Meckelin protein was expressed in affected and unaffected kidney epithelial cells by immunoblotting, and in primary cilia of lamb kidney cyst epithelial cells by immunofluorescence. In contrast to primary cilia of relatively consistent length and morphology in unaffected kidney cells, those of affected cyst-lining cells displayed a range of short and extremely long cilia, as well as abnormal morphologies, such as bulbous regions along the axoneme. Putative cilia fragments were also consistently located within the cyst luminal contents. The abnormal ciliary phenotype was further confirmed in cultured interstitial fibroblasts from affected kidneys. These primary cilia dysmorphologies and length control defects were significantly greater in affected cells compared to unaffected controls. In conclusion, we describe abnormalities involving primary cilia length and morphology in the first reported example of a large animal model of MKS, in which we have identified TMEM67 mutations.

Wave intensity analysis and its application to the coronary circulation

Wave intensity analysis (WIA) is a technique developed from the field of gas dynamics that is now being applied to assess cardiovascular physiology. It allows quantification of the forces acting to alter flow and pressure within a fluid system, and as such it is highly insightful in ascribing cause to dynamic blood pressure or velocity changes. When co-incident waves arrive at the same spatial location they exert either counteracting or summative effects on flow and pressure. WIA however allows waves of different origins to be measured uninfluenced by other simultaneously arriving waves. It therefore has found particular applicability within the coronary circulation where both proximal (aortic) and distal (myocardial) ends of the coronary artery can markedly influence blood flow. Using these concepts, a repeating pattern of 6 waves has been consistently identified within the coronary arteries, 3 originating proximally and 3 distally. Each has been associated with a particular part of the cardiac cycle. The most clinically relevant wave to date is the backward decompression wave, which causes the marked increase in coronary flow velocity observed at the start of the diastole. It has been proposed that this wave is generated by the elastic re-expansion of the intra-myocardial blood vessels that are compressed during systolic contraction. Particularly by quantifying this wave, WIA has been used to provide mechanistic and prognostic insight into a number of conditions including aortic stenosis, left ventricular hypertrophy, coronary artery disease and heart failure. It has proven itself to be highly sensitive and as such a number of novel research directions are encouraged where further insights would be beneficial.

Methamphetamine absorption by skin lipids: accumulated mass, partition coefficients, and the influence of fatty acids

Occupants of former methamphetamine laboratories, often residences, may experience increased exposure through the accumulation of the methamphetamine in the organic films that coat skin and indoor surfaces. The objectives of this study were to determine equilibrium partition coefficients of vapor-phase methamphetamine with artificial sebum (AS-1), artificial sebum without fatty acids (AS-2), and real skin surface films, herein called skin oils. Sebum and skin oil-coated filters were exposed to vapor-phase methamphetamine at concentrations ranging from 8 to 159 ppb, and samples were analyzed for exposure time periods from 2 h to 60 days. For a low vapor-phase methamphetamine concentration range of ~8-22 ppb, the equilibrium partition coefficient for AS-1 was 1500 ± 195 μg/g/ppb. For a high concentration range of 98-112 ppb, the partition coefficient was lower, 459 ± 80 μg/g/ppb, suggesting saturation of the available absorption capacity. The low partition coefficient for AS-2 (33 ± 6 μg/g/ppb) suggests that the fatty acids in AS-1 and skin oil are responsible for much high partition coefficients. We predict that the methamphetamine concentration in skin lipids coating indoor surfaces can exceed recommended surface remediation standards even for air concentrations well below 1 ppb.

A Mixed-Methods Evaluation of a Social Paediatrics Block Rotation for Paediatric Residents

BACKGROUND: Poverty and social injustice have a direct link to health outcomes and health care utilization, especially for children. Understanding the complexity of impact of social determinants on health is essential in providing effective, compassionate care to vulnerable populations. Currently, there is a paucity of literature on the impact of various models of advocacy curricula on pediatric residents and future involvement in advocacy. Social Pediatrics is an approach to child health that focuses on the child, in illness, and in health, within the context of their society, environment, school, and family.

OBJECTIVES: 1) To determine if a social pediatrics rotation greater enables residents to become involved in advocacy projects during their residency and interest for career. 2) To identify resident knowledge translation of the social determinants of health and their impact on the pediatric population. 3) To characterize the barriers and enablers, if any, for residents to engage in advocacy.

DESIGN/METHODS: The Social Pediatrics rotation was embedded in the second year of a postgraduate pediatric curriculum. Knowledge and attitudes of resident participants before and after the rotation was assessed with written tests and surveys. A qualitative descriptive study of community partners and resident perspectives was semi-structured interviews, thematic coding and analysis via an inductive-iterative approach.

RESULTS: 21 residents completed pre-and post- written knowledge tests, and 12 residents completed optional attitudinal surveys. Knowledge increased from 68% prior to rotation, to 80% (p &lt; 0.001) following the rotation. All residents completing written surveys indicated increased likelihood of participating in social pediatrics and advocacy in practice following this rotation. Results from 6 resident and 5 community partner interviews included: enhanced knowledge of social determinants of health, residency curricula development with further mental health placements, future practice models involving vulnerable populations, multi-disciplinary learning opportunities, and advocacy projects both at the patient and community level. Community partners shared experiences of residents demonstrating enthusiasm and engagement in placements, some logistical challenges but value in experiences outside hospital environment, particularly in learning from multidisciplinary team.

CONCLUSION: Pediatric residents demonstrate increase in knowledge of social determinants of health and an increased interest in community advocacy initiatives and vulnerable populations following a block rotation in Social Pediatrics. Community partners valued engagement with pediat-ric residents, identifying key learning opportunities in these unique environments and report few barriers to continued involvement. Future directions include impact on advocacy work or career decisions, and multi-centre collaboration.

P18: MULTIPLE DIAGNOSIS OR CONTINUUM OF DISEASE: MULTICENTRIC CASTLEMAN'S DISEASE

Purpose of Study

Multicentric Castleman's disease (MCD) is a rare lymphoproliferative disorder characterized by peripheral lymphadenopathy (LAD), hepatosplenomegaly(HSM), and B symptoms. It is associated with HIV and HHV8 infection.

We report a case of young woman presented with B symptoms, workup suggestive of lupus but lymph node biopsy (BX) was consistent with MCD. Association of SLE with MCD is rare. We report this case to increase awareness of this potential diagnostic and therapeutic dilemma.

Methods Used

Patient is a 27 yr old black woman presented with malaise, fevers, cough, weight loss, arthralgia, alopecia, numbness of extremities and Raynaud's phenomenon. Patient had skin tightness around the mouth, telangiectasia, digital ulcers, HSM, pitting edema, diffuse LAD and moderate pericardial effusion.

Laboratory results consistent with hemolytic anemia with Hb 5.6 g/dl, direct coombs positive, elevated reticulocyte count, LDH and low haptoglobin. Initial RF, ANA, and all infectious work up including HIV were normal. She was transfused cautiously, with inconclusive LN and bone marrow Bx. Patient left hospital against medical advice.

She presented two days later with altered mental status (AMS) and hypotension. CT head and Lumbar puncture were negative. Hypotension responded to fluids, but no response in AMS. Repeat ANA, AntiSSB, AntiSm, AntiRNP, and Antihistone antibodies were positive. Patient met diagnostic criteria for SLE and was subsequently treated for lupus cerebritis with pulse steroids, with moderate improvement in mental status. Repeat LNBX revealed reactive lymphadenitis with features of MCD, HHV8 negative. Patient was treated with IL-6 inhibitor Siltuximab, with significant improvement in mental status.

Summary of Results

MCD is a rare angiolymphoproliferative disorder of unclear etiology. Most cases occur in middle aged men and are associated with immunosuppression where as SLE is common in women of child bearing age. Reported cases of MCD in association with SLE are common in immunocompetent young women. Our patient is a young woman, HIV/HHV8 negative with good response to Siltuximab, favoring MCD.

Conclusions

It is unclear whether this finding of MCD and SLE represents an overlap or a pure association. However, this phenomenon needs further investigation.

Accumulation of gas-phase methamphetamine on clothing, toy fabrics, and skin oil

To better understand methamphetamine exposure and risk for occupants of former residential clandestine methamphetamine laboratories, we measured the dynamic accumulation of methamphetamine in skin oil, cotton and polyester (PE) clothing, upholstery, and toy fabric (substrates) exposed to 15-30 ppb (91-183 μg/m(3)) neutral methamphetamine in air for up to 60 days. The average equilibrium partition coefficients at 30% RH, in units of μg of methamphetamine per gram of substrate per ppb, are 3.0 ± 0.2 for a PE baby blanket, 5.6 ± 3.5 for a PE fabric toy, 3.7 ± 0.2 for a PE shirt, 18.3 ± 8.0 for a PE/cotton upholstery fabric, and 1200 ± 570 in skin oil. The partition coefficients at 60% RH are 4.5 ± 0.4, 5.2 ± 2.1, 4.5 ± 0.6, 36.1 ± 3.6, and 1600 ± 1100 μg/(g ppb), respectively. There was no difference in the partition coefficient for a clean and skin-oil-soiled cotton shirt [15.3 ± 2.1 μg/(g ppb) @ 42 days]. Partition coefficients for skin oil may be sensitive to composition. 'Mouthing' of cloth is predicted to be the dominant exposure pathway [60 μg/(kg body weight*ppb)] for a toddler in former meth lab, and indoor air concentrations would have to be very low (0.001 ppb) to meet the recommended reference dose for children.

PRACTICAL IMPLICATIONS

Gas-phase methamphetamine transfers to and accumulates on clothing, toys and other fabrics significantly increases risk of ingestion of methamphetamine. Current remediation methods should consider measurement of postremediation gas-phase air concentrations of methamphetamine in addition to surface wipe samples.