Right Ventricle-Pulmonary Artery Coupling in Patients Undergoing Cardiac Interventions

PURPOSE OF REVIEW

This review aims to summarize the fundamentals of RV-PA coupling, its non-invasive means of measurement, and contemporary understanding of RV-PA coupling in cardiac surgery, cardiac interventions, and congenital heart disease.

RECENT FINDINGS

The need for more accessible clinical means of evaluation of RV-PA coupling has driven researchers to investigate surrogates using cardiac MRI, echocardiography, and right-sided pressure measurements in patients undergoing cardiac surgery/interventions, as well as patients with congenital heart disease. Recent research has aimed to validate these alternative means against the gold standard, as well as establish cut-off values predictive of morbidity and/or mortality. This emerging evidence lays the groundwork for identifying appropriate RV-PA coupling surrogates and integrating them into perioperative clinical practice.

Right ventricular performance during acute hypoxic exercise

Acute hypoxia increases pulmonary arterial (PA) pressures, though its effect on right ventricular (RV) function is controversial. The objective of this study was to characterize exertional RV performance during acute hypoxia. Ten healthy participants (34 ± 10 years, 7 males) completed three visits: visits 1 and 2 included non-invasive normoxic (fraction of inspired oxygen (F i O 2 ${F_{{\mathrm{i}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) = 0.21) and isobaric hypoxic (F i O 2 ${F_{{\mathrm{i}}{{\mathrm{O}}_{\mathrm{2}}}}}$  = 0.12) cardiopulmonary exercise testing (CPET) to determine normoxic/hypoxic maximal oxygen uptake (V ̇ O 2 max ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{max}}}}$ ). Visit 3 involved invasive haemodynamic assessments where participants were randomized 1:1 to either Swan-Ganz or conductance catheterization to quantify RV performance via pressure-volume analysis. Arterial oxygen saturation was determined by blood gas analysis from radial arterial catheterization. During visit 3, participants completed invasive submaximal CPET testing at 50% normoxicV ̇ O 2 max ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{max}}}}$ and again at 50% hypoxicV ̇ O 2 max ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{max}}}}$ (F i O 2 ${F_{{\mathrm{i}}{{\mathrm{O}}_{\mathrm{2}}}}}$  = 0.12). Median (interquartile range) values for non-invasiveV ̇ O 2 max ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{max}}}}$ values during normoxic and hypoxic testing were 2.98 (2.43, 3.66) l/min and 1.84 (1.62, 2.25) l/min, respectively (P < 0.0001). Mean PA pressure increased significantly when transitioning from rest to submaximal exercise during normoxic and hypoxic conditions (P = 0.0014). Metrics of RV contractility including preload recruitable stroke work, dP/dtmax , and end-systolic pressure increased significantly during the transition from rest to exercise under normoxic and hypoxic conditions. Ventricular-arterial coupling was maintained during normoxic exercise at 50%V ̇ O 2 max ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{max}}}}$ . During submaximal exercise at 50% of hypoxicV ̇ O 2 max ${\dot V_{{{\mathrm{O}}_{\mathrm{2}}}{\mathrm{max}}}}$ , ventricular-arterial coupling declined but remained within normal limits. In conclusion, resting and exertional RV functions are preserved in response to acute exposure to hypoxia at anF i O 2 ${F_{{\mathrm{i}}{{\mathrm{O}}_{\mathrm{2}}}}}$  = 0.12 and the associated increase in PA pressures. KEY POINTS: The healthy right ventricle augments contractility, lusitropy and energetics during periods of increased metabolic demand (e.g. exercise) in acute hypoxic conditions. During submaximal exercise, ventricular-arterial coupling decreases but remains within normal limits, ensuring that cardiac output and systemic perfusion are maintained. These data describe right ventricular physiological responses during submaximal exercise under conditions of acute hypoxia, such as occurs during exposure to high altitude and/or acute hypoxic respiratory failure.

Obesity dominates early effects on cardiac structure and arterial stiffness in people with type 2 diabetes

OBJECTIVE

Type 2 diabetes (T2D) and obesity are global epidemics leading to excess cardiovascular disease (CVD). This study investigates standard and novel cardiac MRI parameters to detect subclinical cardiac and central vascular dysfunction in inactive people with and without T2D.

METHODS

Physically inactive age and BMI-similar premenopausal women and men with ( n  = 22) and without [ n  = 34, controls with overweight/obesity (CWO)] uncomplicated T2D were compared to an age-similar and sex-similar reference control cohort ( n  = 20). Left ventricular (LV) structure, function, and aortic stiffness were assessed by MRI. Global arterial pulse wave velocity (PWV) was assessed using carotid-to-femoral applanation tonometry. Regional PWV was measured via 2D phase-contrast MRI and 4D flow MRI.

RESULTS

Global arterial PWV did not differ between CWO and T2D. 2D PC-MRI PWV in the ascending aorta was higher in people with T2D compared with CWOs ( P  < 0.01). 4D flow PWV in the thoracic aorta was higher in CWO ( P  < 0.01), and T2D ( P  < 0.001) compared with RC. End-diastolic volume, end-systolic volume, stroke volume, and cardiac output were lower in CWO and T2D groups compared with reference control.

CONCLUSION

Subclinical changes in arterial stiffening and cardiac remodeling in inactive CWO and T2D compared with reference control support obesity and/or physical inactivity as determinants of incipient CVD complications in uncomplicated T2D. Future studies should determine the mechanistic causes of the CVD complications in greater detail in order to create therapeutic targets.

CLINICAL TRIAL REGISTRATION

Cardiovascular Mechanisms of Exercise Intolerance in Diabetes and the Role of Sex (NCT03419195).

Leave events among Aboriginal and Torres Strait Islander people: a systematic review

BACKGROUND

Leave events are a public health concern resulting in poorer health outcomes. In Australia, leave events disproportionally impact Aboriginal and Torres Strait Islander people. A systematic review was conducted to explore the causes of leave events among Aboriginal and Torres Strait Islander people and strategies to reduce them.

METHODS

A systematic review was conducted using Medline, Web of Science, Embase and Informit, a database with a strong focus on relevant Australian content. Additionally, we examined the references of the records included, and performed a manual search using Google, Google scholar and the Australia's National Institute for Aboriginal and Torres Strait Islander Health Research. Two independent reviewers screened the records. One author extracted the data and a second author reviewed it. To appraise the quality of the studies the Mixed Methods Appraisal Tool was used as well as the Aboriginal and Torres Strait Islander Quality Appraisal Tool. A narrative synthesis was used to report quantitative findings and an inductive thematic analysis for qualitative studies and reports.

RESULTS

We located 421 records. Ten records met eligibility criteria and were included in the systematic review. From those, four were quantitative studies, three were qualitative studies and three reports. Five records studied data from the Northern Territory, two from Western Australia, two from New South Whales and one from Queensland. The quantitative studies focused on the characteristics of the patients and found associations between leave events and male gender, age younger than 45 years and town camp residency. Qualitative findings yielded more in depth causes of leave events evidencing that they are associated with health care quality gaps. There were multiple strategies suggested to reduce leave events through adapting health care service delivery. Aboriginal and Torres Strait Islander representation is needed in a variety of roles within health care provision and during decision-making.

CONCLUSION

This systematic review found that multiple gaps within Australian health care delivery are associated with leave events among Aboriginal and Torres Strait Islander people. The findings suggest that reducing leave events requires better representation of Aboriginal and Torres Strait Islander people within the health workforce. In addition, partnership with Aboriginal and Torres Strait Islander people is needed during the decision-making process in providing health services that meet Aboriginal and Torres Strait Islander cultural needs.

Non-fatal injuries among boys and girls presenting to Red Cross War Memorial Children's Hospital, Cape Town, South Africa

BACKGROUND

In South Africa (SA), road traffic injuries, homicides and burns are the leading causes of injury-related deaths among children. Injury-related deaths are well documented for SA, but this is not the case for non-fatal injuries.

OBJECTIVES

To describe the non-fatal injuries sustained among children aged 0 - 13 years, to identify any significant sex differences by age group, cause of injury, admission status and injury severity.

METHODS

The trauma unit database from 1997 to 2016 at Red Cross War Memorial Children's Hospital, Cape Town, was utilised for this analysis. The prevalence of injuries and the boy/girl ratios with 95% confidence intervals (CIs) were reported.

RESULTS

Analysis indicated significant differences by sex for individual injury causes (transport, assault, burns, falls and other injuries), age group, injury severity and admission status. Moderately severe injuries were largely caused by burns, while severe injuries were mostly transport related. Boys had significantly higher proportions of all injury causes. The boy/girl ratio was lowest for assault (1:18), where significantly more girls aged 1 - 3 and 4 - 6 years were injured. Rape/sexual assault was 5.5 times higher for girls, with a significantly higher proportion of moderate-severity injuries (87%; 95% CI 84.7 - 89.4).

CONCLUSION

The study findings call for a more targeted prevention response for boy and girl children. Interventions should be targeted at the prevention of burns, traffic collisions and interpersonal violence, in particular sexual assaults against girls.

Hemodynamically Unloading the Distal Pulmonary Circulation in Pulmonary Hypertension: A Modeling Study

Pulmonary hypertension (PH) is a progressive disease that is characterized by a gradual increase in both resistive and reactive pulmonary arterial (PA) impedance. Previous studies in a rodent model of PH have shown that reducing the hemodynamic load in the left lung (by banding the left PA) reverses this remodeling phenomenon. However, banding a single side of the pulmonary circulation is not a viable clinical option, so-using in silico modeling-we evaluated if the banding effect can be recreated by replacing the proximal vasculature with a compliant synthetic PA. We developed a computational model of the pulmonary circulation by combining a one-dimensional model of the proximal vasculature with a zero-dimensional line transmission model to the 12th generation. Using this model, we performed four simulations: (1) Control; (2) PH; (3) PH with a stenosis in the left PA; and (4) PH with proximal vessel compliance returned to Control levels. Simulations revealed that vascular changes associated with PH result in an increase in pulse pressure (PP), maximum pressure (Pmax), maximum wall shear stress (WSS), and maximum circumferential stress (σθθ) relative to controls, in the distal circulation. Banding the left PA reduced these measurements of hemodynamic stress in the left lung, but increases them in the right lung. Furthermore, left PA banding increased reactive PA impedance. However, returning the proximal PA compliance to Control levels simultaneously decreased all measures of hemodynamic stress in both lungs, and returned reactive PA impedance to normal levels. In conclusion, if future in vivo studies support the idea of hemodynamic unloading as an effective therapy for PH, this can be surgically achieved by replacing the proximal PA with a compliant prosthesis, and it will have the added benefit of reducing reactive right ventricular afterload.

A modified Dabestani-Mahan formula estimates a normal pulmonary artery systolic pressure: a single-center retrospective study

Background

Pulmonary artery systolic pressure (PASP) is increasingly used as an important datapoint in clinical decision-making and prognostication even in specialties outside of cardiology. Estimation of PASP by Doppler quantification using tricuspid regurgitation (TR) peak velocity is commonly used and correlates well with invasive measurement by right heart catheterization. Further study of transthoracic echocardiogram (TTE) techniques to estimate PASP is needed to provide this datapoint in the absence of sufficient Doppler data for the TR peak velocity method. One technique using right ventricular outflow tract acceleration time (AT) to estimate mean pulmonary artery pressure (MPAP) has been proposed by Dabestani Et al. by the equation MPAP=90-(0.62x AT). Assuming a linear relationship between MPAP and PASP, as suggested by Chemla Et al. by MPAP=(0.61xPASP)+2, a modified formula PASP=145-AT could possibly estimate a normal PASP ≤25 mmHg.

Purpose

To examine if a modified Dabestani-Mahan formula PASP=145-AT can estimate a normal PASP ≤25 mmHg as calculated by the TR peak velocity method.

Methods

We queried the electronic medical record at our institution for a sample of 300 patients who had a TTE performed between 2017 and 2020. Each TTE was reviewed and PASP was estimated for each using the TR peak velocity method. A right atrial pressure of 3 mmHg, 8 mmHg, or 15 mmHg was used in the estimation based on inferior vena cava diameter and collapsibility in keeping with the 2015 American Society of Echocardiography guidelines. A short axis view of pulmonary flow using the pulse-waved Doppler sample volume over the transpulmonary valve jet was then reviewed. The time from onset of ejection to peak flow velocity was measured manually as AT in milliseconds using Change Healthcare Cardiology Web Software Package 14.1.1. The measured AT was averaged over three cardiac cycles. Patients with a heart rate between 60 and 100 beats per minute at time of TTE and with sufficient Doppler data to estimate PASP by TR peak velocity and to measure AT were included in a logistic regression analysis.

Results

154 patients were included in the statistical analysis. Patients who had a right ventricular outflow tract acceleration time greater than 120 milliseconds, giving a PASP ≤25 mmHg by the modified formula PASP=145-AT, had a 36 times greater odds of having a PASP ≤25 mmHg by the TR peak velocity method (OR=36.0, 95% CI=10.36–125.12, p&lt;0.001).

Conclusion(s)

Based on a single-center sample, a right ventricular outflow tract acceleration time greater than 120 milliseconds could be used to estimate a normal pulmonary artery systolic pressure less than or equal to 25 mmHg in the absence of sufficient Doppler data for the commonly used TR peak velocity method.

Funding Acknowledgement

Type of funding sources: None.

Ventricular-vascular coupling is predictive of adverse clinical outcome in paediatric pulmonary arterial hypertension

Aims

Ventricular–vascular coupling, the ratio between the right ventricle’s contractile state (E_es) and its afterload (E_a), may be a useful metric in the management of paediatric pulmonary arterial hypertension (PAH). In this study we assess the prognostic capacity of the ventricular–vascular coupling ratio (E_es/E_a) derived using right ventricular (RV) pressure alone in children with PAH.

Methods

One hundred and thirty paediatric patients who were diagnosed with PAH via right heart catheterisation were retrospectively reviewed over a 10-year period. Maximum RV isovolumic pressure and end-systolic pressure were estimated using two single-beat methods from Takeuchi et al (E_es/E_a_(Takeuchi)) and from Kind et al (E_es/E_a_(Kind)) and used with an estimate of end-systolic pressure to compute ventricular–vascular coupling from pressure alone. Patients were identified as either idiopathic/hereditary PAH or associated PAH (IPAH/HPAH and APAH, respectively). Haemodynamic data, clinical functional class and clinical worsening outcomes—separated into soft (mild) and hard (severe) event categories—were assessed. Adverse soft events included functional class worsening, syncopal event, hospitalisation due to a proportional hazard-related event and haemoptysis. Hard events included death, transplantation, initiation of prostanoid therapy and hospitalisation for atrial septostomy and Pott’s shunt. Cox proportional hazard modelling was used to assess whether E_es/E_a was predictive of time-to-event.

Results

In patients with IPAH/HPAH, E_es/E_a_(Kind) and E_es/E_a_(Takeuchi) were both independently associated with time to hard event (p=0.003 and p=0.001, respectively) and when adjusted for indexed pulmonary vascular resistance (p=0.032 and p=0.013, respectively). Neither E_es/E_a_(Kind) nor E_es/E_a_(Takeuchi) were associated with time to soft event. In patients with APAH, neither E_es/E_a_(Kind) nor E_es/E_a_(Takeuchi) were associated with time to hard event or soft event.

Conclusions

E_es/E_a derived from pressure alone is a strong independent predictor of adverse outcome and could be a potential powerful prognostic tool for paediatric PAH.

Massive Perivillous Fibrin Deposition and Chronic Histiocytic Intervillositis a Complication of SARS-CoV-2 Infection

An emerging complication of COVID-19 (SARS-CoV-2) infection is reported. A 23-year-old patient presented with high temperature and reduced fetal movements at 25 + 5/40 weeks of gestation. RT-PCR proved maternal COVID-19 infection. Ultrasound examination confirmed intrauterine death. Placenta histology showed necrosis of the villous trophoblast, associated with Chronic Histiocytic Intervillositis (CHI) and Massive Perivillous Fibrin Deposition (MPFD) with up to 90% - of the intervillous spaces being involved. Immunohistochemistry showed CD68 positive histiocytes in the intervillous spaces and the villous trophoblast was positive for the COVID-19 spike protein. RNA scope signal was indicative of the presence of the viral genome and active viral replication in the villous trophoblastic cells, respectively. MPFD is a gradually developing end-stage disease with various etiology, including autoimmune and alloimmune maternal response to antigens expressed at the feto-maternal interface and frequently accompanies chronic alloimmune villitis or histiocytic intervillositis. Covid-19 infection is associated with similar pattern of histological changes of the placenta leading to placental insufficiency and fetal death. This case report supports maternal- fetal vertical transmission of SARS-CoV-2 virus leading to placental insufficiency and fetal demise. MPFD and CHI appear to be the typical placental histology for SARS-CoV-2 virus infection associated fetal demise.

Increased right ventricular uptake on (99m Tc)-sestamibi SPECT myocardial perfusion imaging as a marker of elevated pulmonary artery systolic pressure measured by Doppler echocardiography

Funding Acknowledgements

Type of funding sources: None.

Background

Though prior work has been done, the significance of the not uncommon finding of increased right ventricular (RV) tracer uptake in patients undergoing (99m Tc)-sestamibi SPECT myocardial perfusion imaging remains poorly defined and this finding not been systemically integrated into the interpretation of the study, despite likely carrying both diagnostic and prognostic relevance for the patient.

Purpose

To examine if the presence of increased RV tracer uptake in patients undergoing myocardial perfusion imaging with same-day protocol (99m Tc)-sestamibi SPECT is associated with a higher pulmonary artery systolic pressure (PASP) measured non-invasively with transthoracic Doppler echocardiography 

Methods

Patients who underwent myocardial perfusion imaging with same-day protocol (99m Tc)-sestamibi SPECT at a single academic health system between 2017-2020 were retrospectively enrolled. Those patients who had a transthoracic echocardiogram performed within 60 days of the nuclear study with sufficient Doppler data to estimate pulmonary artery systolic pressure(PASP) using the tricuspid regurgitation peak velocity method were included. A right atrial pressure of either 3 mmHg, 8 mmHg, or 15 mmHg was used in the calculation of PASP in keeping with the 2015 American Society of Echocardiography guidelines. The rest images for each nuclear study were reviewed and analyzed for the presence of RV tracer uptake. RV uptake was graded as either 0 or "no RV uptake", 1+ or "partial RV uptake", or  2+ or "complete RV uptake".  The nuclear studies were grouped accordingly and the mean PASP for each group was computed.  The mean PASP was also computed for a combined group of patients who demonstrated either 1+ or 2+ RV uptake. Statistical analysis using a t-test was performed to compare the mean PASP of each patient group. 

Results

193 patients were included in the analysis. Of those, 123(63%) demonstrated "no RV uptake",  58(31%) demonstrated 1+ or "partial RV uptake", and 12(6%) demonstrated 2+ or "complete RV uptake". 70 patients(36%) had either 1+ or 2 + RV uptake. The mean PASP was 27.2 ± 7 mmHg for the "no RV uptake" group, 28.3 ± 9 mmHg for the 1+ RV uptake group and 41. 6 ± 14 mmHg for the 2+ RV uptake group. When combined, patients demonstrating 1+ or 2+ RV uptake had a mean PASP of 30.6 ± 11 mmHg. There was no statistical difference in the mean PASP of the "no RV uptake" group and the 1+ or "partial RV uptake group" (p = 0.434). The difference in mean PASP between the "no RV uptake" group and the combined 1+ or 2+ RV uptake group was statistically significant(p = 0.028). 

Conclusion

In a small single health system sample, patients undergoing (99m Tc)-sestamibi SPECT myocardial perfusion imaging who have either partial or complete RV uptake on rest images have an increased pulmonary artery systolic pressure compared to patients who do not exhibit this finding.

Right ventricular function and cardiopulmonary performance among patients with heart failure supported by durable mechanical circulatory support devices

BACKGROUND

Patients with continuous-flow left ventricular assist devices (CF-LVADs) experience limitations in functional capacity and frequently, right ventricular (RV) dysfunction. We sought to characterize RV function in the context of global cardiopulmonary performance during exercise in this population.

METHODS

A total of 26 patients with CF-LVAD (aged 58 ± 11 years, 23 males) completed a hemodynamic assessment with either conductance catheters (Group 1, n = 13) inserted into the right ventricle to generate RV pressure‒volume loops or traditional Swan‒Ganz catheters (Group 2, n = 13) during invasive cardiopulmonary exercise testing. Hemodynamics were collected at rest, 2 sub-maximal levels of exercise, and peak effort. Breath-by-breath gas exchange parameters were collected by indirect calorimetry. Group 1 participants also completed an invasive ramp test during supine rest to determine the impact of varying levels of CF-LVAD support on RV function.

RESULTS

In Group 1, pump speed modulations minimally influenced RV function. During upright exercise, there were modest increases in RV contractility during sub-maximal exercise, but there were no appreciable increases at peak effort. Ventricular‒arterial coupling was preserved throughout the exercise. In Group 2, there were large increases in pulmonary arterial, left-sided filling, and right-sided filling pressures during sub-maximal and peak exercises. Among all participants, the cardiac output‒oxygen uptake relationship was preserved at 5.8:1. Ventilatory efficiency was severely abnormal at 42.3 ± 11.6.

CONCLUSIONS

Patients with CF-LVAD suffer from limited RV contractile reserve; marked elevations in pulmonary, left-sided filling, and right-sided filling pressures during exercise; and severe ventilatory inefficiency. These findings explain mechanisms for persistent reductions in functional capacity in this patient population.

Radiologists are increasingly recommending follow-up of chest radiographs: a 10-year review

PURPOSE

To assess for changes in trends of GP chest radiograph reporting over a 10-year period and to assess if there has been a change in recommendations for follow-up.

METHODS

Retrospective study of an Irish tertiary referral center. The total number of GP-referred chest x-rays performed per year from 2007 to 2017 are recorded. One-hundred male/100 female GP-referred chest x-rays are chosen at random from NIMIS data for each of 2007, 2010, 2013, and 2017. Reports are analyzed with regard to abnormal findings, recommendation for follow-up, and yield of follow-up imaging.

RESULTS

There were 4917 GP CXRs performed in 2007, 4856 in 2010, 5561 in 2013, and 6492 in 2017. Follow-up was recommended in 17 studies(8.5%) in 2007, 19 studies(9.5%) in 2010, 22 studies(11%) in 2013, and 27 studies(13.5%) in 2017. Indications for follow-up recommendation were largely to ensure resolution of infection (52%) or for nodule surveillance (43%). There has been a notable increase in lung nodule follow-up, with suggested follow-ups increasing from 6 in 2007, to 7 in 2010, 9 in 2013, and 14 in 2017, an increase of 58%.

CONCLUSION

Along with the increase in the quantity of GP-referred chest radiographs over the past 10 years, suggestions for follow-up have increased, particularly for nodule surveillance. Reasons for this increase may include lack of availability of CT to GPs for lung cancer screening, insensitivity of plain radiographs to early cancer detection, and possible fear of litigation for missing lesions, making radiologists more cautious.

New insights into resting and exertional right ventricular performance in the healthy heart through real-time pressure-volume analysis

KEY POINTS

Despite growing interest in right ventricular form and function in diseased states, there is a paucity of data regarding characteristics of right ventricular function - namely contractile and lusitropic reserve, as well as ventricular-arterial coupling, in the healthy heart during rest, as well as submaximal and peak exercise. Pressure-volume analysis of the right ventricle, during invasive cardiopulmonary exercise testing, demonstrates that that the right heart has enormous contractile reserve, with a three- or fourfold increase in all metrics of contractility, as well as myocardial energy production and utilization. The healthy right ventricle also demonstrates marked augmentation in lusitropy, indicating that diastolic filling of the right heart is not passive. Rather, the right ventricle actively contributes to venous return during exercise, along with the muscle pump. Ventricular-arterial coupling is preserved during submaximal and peak exercise in the healthy heart.

ABSTRACT

Knowledge of right ventricular (RV) function has lagged behind that of the left ventricle and historically, the RV has even been referred to as a 'passive conduit' of lesser importance than its left-sided counterpart. Pressure-volume (PV) analysis is the gold standard metric of assessing ventricular performance. We recruited nine healthy sedentary individuals free of any cardiopulmonary disease (42 ± 12 years, 78 ± 11 kg), who completed invasive cardiopulmonary exercise testing during upright ergometry, while using conductance catheters inserted into the RV to generate real-time PV loops. Data were obtained at rest, two submaximal levels of exercise below ventilatory threshold, to simulate real-world scenarios/activities of daily living, and maximal effort. Breath-by-breath oxygen uptake was determined by indirect calorimetry. During submaximal and peak exercise, there were significant increases in all metrics of systolic function by three- to fourfold, including cardiac output, preload recruitable stroke work, and maximum rate of pressure change in the ventricle (dP/dtmax ), as well as energy utilization as determined by stroke work and pressure-volume area. Similarly, the RV demonstrated a significant, threefold increase in lusitropic reserve throughout exercise. Ventricular-arterial coupling, defined by the quotient of end-systolic elastance and effective arterial elastance, was preserved throughout all stages of exercise. Maximal pressures increased significantly during exercise, while end-diastolic volumes were essentially unchanged. Overall, these findings demonstrate that the healthy RV is not merely a passive conduit, but actively participates in cardiopulmonary performance during exercise by accessing an enormous amount of contractile and lusitropic reserve, ensuring that VA coupling is preserved throughout all stages of exercise.

Beyond HOSPEX: what is the additional training value of military hospital exercises (HOSPEX)?

BACKGROUND

The use of simulation in clinical environments is a frequently used adjunct to training individuals and teams. The military uses clinical simulation to train large numbers of personnel, standardise patient pathways and sustain specific skills to ensure medical personnel are prepared to deploy in their clinical roles.

METHODS

As part of a North Atlantic Treaty Organization (NATO) exercise, 256 Field Hospital (Reserves) deployed a team of clinicians to simulate a role 2 basic field hospital. This hospital exercise (HOSPEX) involved training, and a 4-day real-time exercise with casualty simulation. A retrospective survey of all clinical personnel was conducted to analyse the utility of the exercise on their understanding of their job role, the workings of the field hospital and their confidence in deploying on operations.

RESULTS

39 personnel were surveyed, with questions graded on a modified Likert scale. 41% had previous operational experience in their current job role. A significantly higher proportion of respondents graded their understanding of their job role, and the field hospital overall, as good or excellent having completed the exercise (p<0.01), and 90% felt more confident in fulfilling their operational role postexercise. 90% of respondents had previous experience of simulation, and 94% of these rated the military simulation as being more beneficial than civilian equivalents.

DISCUSSION

With a shift towards simulation in medical training, opportunities have arisen within HOSPEX to develop additional skills for teams and individuals. Simulation is especially important in personnel who have not had previous operational experience, who may deploy on first time operations in senior clinical and leadership roles.

CONCLUSION

HOSPEXs are perceived as being extremely useful by clinical personnel preparing for future operational deployment. HOSPEX simulation has prepared the military for varied operations since its inception, and the paradigm has potential for extension into civilian training for high intensity medical responses.

Efficacy and cultural appropriateness of psychosocial interventions for paediatric burn patients and caregivers: a systematic review

Background

Paediatric burns are highly painful and traumatising injuries that are overrepresented among Aboriginal and Torres Strait Islander people. Paediatric burn patients’ pain remains poorly managed by pharmacological interventions, leading to increased anxiety, distress, and trauma in patients and their caregivers. Non-pharmacological psychosocial interventions have been suggested as effective in reducing pain and psychological morbidities among paediatric burn patients and their caregivers; however, their degree of effectiveness and appropriateness for Aboriginal and Torres Strait Islander people is unclear.

Methods

A non-date restricted systematic review was conducted through four databases. Studies published in English assessing psychosocial interventions on paediatric burn patients’ physical pain along with theirs and/or their caregiver’s anxiety, distress, or trauma symptoms were identified and included in this review. Included studies were assessed for their ability to reduce one of the outcomes of interests and for their reflection of Aboriginal and Torres Strait Islander peoples’ perspectives of health.

Results

Of the 3178 identified references, 17 were eligible. These include distraction based techniques (n = 8), hypnosis/familiar imagery (n = 2), therapeutic approaches (n = 4), and patient preparation/procedural control (n = 3). Distraction techniques incorporating procedural preparation reduced pain, while discharge preparation and increased ‘patient control’ reduced patient and caregiver anxiety; and internet based Cognitive Behaviour Therapy reduced short-term but not long-term post-traumatic stress symptoms. No interventions reflected Aboriginal and Torres Strait Islander peoples’ perspectives of health; and few targeted caregivers or focused on reducing their symptoms.

Conclusions

The development and assessment of psychosocial interventions to appropriately meet the needs of Aboriginal and Torres Strait Islander paediatric burn patients is required.

Are we Over-Imaging the Obese Patient with Suspected Pulmonary Embolus in Ireland

Aims To assess if there was a significant difference in the number of positive studies for pulmonary embolism between obese and non obese patients. Methods A retrospective analysis of all CTPAs performed in our institution over one year in patients aged 18-50 was performed. Data regarding the diagnosis of pulmonary embolism, the presence of airways disease, other significant chest findings, D dimer values and demographic data including a BMI surrogate was obtained. Results Two hundred and thirty CTPAs were performed in our institution over 12 months. Two hundred and twenty-one were included for analysis, of which 129 were male and 92 were female. Sixty-nine (31%) patients were classified as obese. Eleven (16%) of these had positive studies. One hundred and fifty-two patients were in the non obese category, of which 24 (15%) had positive studies. Conclusions We are not over imaging the obese patient, but are over imaging patients in general with suspected PE, but are exposing a significant number overall, to unnecessary radiation.

The role of microbiota and inflammation in self-judgement and empathy: implications for understanding the brain-gut-microbiome axis in depression

RATIONALE

The gut-brain axis includes bidirectional communication between intestinal microbiota and the central nervous system. Bifidobacterium and Lactobacillus spp. have been implicated in psychological health, such as depression, through various pathways (e.g. inflammation). Research needs a better understanding of direct and indirect effects through examination of psychological factors that make people susceptible to, or offer protection against, depression.

OBJECTIVE

This study investigated the relationships between gut microbiota, inflammation and psychological risk and resilience factors for depression.

METHODS

Forty participants (13 m/27 f) recruited from the general population completed self-report questionnaires for depression, self-judgement, over-identification and affective and cognitive empathy. Faecal and blood samples were taken to assay microbiota (Bifidobacterium; Lactobacillus spp.) and pro-inflammatory molecules (C-reactive protein, CRP and interleukin-6, IL-6), respectively.

RESULTS

Hierarchical regression analyses (controlling for sex, age and the shared variance of risk and resilience factors) showed that (i) cognitive depression was significantly predicted by negative self-judgement and reduced cognitive empathy; (ii) abundance of Lactobacillus spp. was directly related to positive self-judgement but only indirectly to cognitive depression and lower affective empathy (both through self-judgement); and (iii) CRP was the strongest predictor of reduced cognitive empathy, with suppression effects seen for age (negative) and IL-6 (positive) after controlling for CRP.

CONCLUSIONS

Findings suggest that lactobacilli and inflammation may be differentially associated with mood disorder via brain mechanisms underpinning self-judgement and cognitive empathy, respectively. Further trials investigating interventions to increase Lactobacillus spp. in depression would benefit from direct measures of self-judgement and affective empathic distress, whilst those that aim to reduce inflammation should investigate cognitive empathy.

Strain and Rotational Mechanics in Children With Single Left Ventricles After Fontan

BACKGROUND

Left ventricular (LV) mechanics in patients with different single morphologic LV subtypes, including tricuspid atresia, double-inlet left ventricle, and pulmonary atresia with intact ventricular septum, remain poorly studied. Given that histologic studies indicate differences in LV myocardial fiber orientation, we hypothesized that this may result in altered LV mechanics. The aim of this study was to evaluate the influence of LV morphology on LV mechanics.

METHODS

Fifty-two children with single left ventricles after Fontan operation and age-matched control subjects were prospectively enrolled. Using two-dimensional speckle-tracking echocardiography, longitudinal strain was measured in the four-, three-, and two-chamber long-axis planes, and circumferential strain was measured at the basal, mid, and apical short-axis planes. Apical and basal rotation were measured, and twist and torsion were calculated. We compared strain and rotational mechanics in cases versus control subjects and among LV subtypes.

RESULTS

Compared with control subjects, subjects with single left ventricles had similar LV end-diastolic dimensions but significantly decreased ejection fractions. The single left ventricle cohort had normal global longitudinal strain (P = .20) but lower basal mean circumferential strain (P < .0001). Single left ventricle subjects had higher apical rotation (P = .0001) but decreased basal rotation (P = .0007); there was no difference in twist but increased torsion (P = .001). LV subtypes had different four-chamber (P = .01), two-chamber (P = .006), and global longitudinal strain (P = .01), lowest in the pulmonary atresia with intact ventricular septum subtype.

CONCLUSIONS

Longitudinal LV strain was preserved in children with single left ventricles after Fontan. A pattern of reduced basal circumferential strain and rotation with an increase in apical rotation and torsion in the single left ventricle cohort may be related to differences in myofiber orientation, increased fibrosis, and the impact of altered loading conditions throughout palliation. Decreased longitudinal strain in the pulmonary atresia with intact ventricular septum group may also reflect detrimental interventricular interactions.

Human papillomavirus and oral and oropharyngeal carcinoma: the essentials

There is a global increase in the prevalence of human papillomavirus (HPV)-driven oropharyngeal squamous cell carcinoma (OPSCC) in Australia and New Zealand. Risk factors for HPV-positive OPSCC are male gender, white race, age older than 40 but younger than 59 years old, having multiple lifetime sex partners, having oro-genital and oro-anal sex. High-risk HPV subtypes play a major role in the pathogenesis of OPSCC, however, they play a much lesser role in oral squamous cell carcinoma (OSCC). Among the laboratory tests used to detect oncogenic HPV infection, polymerase chain reaction is a sensitive method but does not reflect the role of HPV in oncogenesis. While widely used, p16 immunohistochemistry is both a sensitive and a specific surrogate marker for oncogenic HPV infection in OPSCC, but not in OSCC. However, it is a useful prognostic marker in OPSCC. The current gold standard to accurately detect oncogenic HPV infection is E6/E7 mRNAin situ hybridization. Because both HPV-positive and p16-positive OPSCC have better short-term prognoses there is current debate and trials on treatment de-escalation in HPV-positive OPSCC. Dental practitioners can play an important role in early diagnosis of HPV-positive OPSCC.

Glucagon-like peptide-1 receptor antagonism impairs basal exercise capacity and vascular adaptation to aerobic exercise training in rats

Cardiorespiratory fitness (CRF) inversely predicts cardiovascular (CV) mortality and CRF is impaired in people with type 2 diabetes (T2D). Aerobic exercise training (ET) improves CRF and is associated with decreased risk of premature death in healthy and diseased populations. Understanding the mechanisms contributing to ET adaptation may identify targets for reducing CV mortality of relevance to people with T2D. The antihyperglycemic hormone glucagon-like peptide-1 (GLP-1) influences many of the same pathways as exercise and may contribute to CV adaptation to ET. We hypothesized that GLP-1 is necessary for adaptation to ET. Twelve-week-old male Wistar rats were randomized (n = 8-12/group) to receive PBS or GLP-1 receptor antagonist (exendin 9-39 (Ex(9-39)) via osmotic pump for 4 weeks ± ET. CRF was greater with ET (P < 0.01). Ex(9-39) treatment blunted CRF in both sedentary and ET rats (P < 0.001). Ex(9-39) attenuated acetylcholine-mediated vasodilation, while this response was maintained with Ex(9-39)+ET (P = 0.04). Aortic stiffness was greater with Ex(9-39) (P = 0.057) and was made worse when Ex(9-39) was combined with ET (P = 0.004). Ex vivo aortic vasoconstriction with potassium and phenylephrine was lower with Ex(9-39) (P < 0.0001). Carotid strain improved with PBS + ET but did not change in the Ex(9-39) rats with ET (P < 0.0001). Left ventricular mitochondrial respiration was elevated with Ex(9-39) (P < 0.02). GLP-1 receptor antagonism impairs CRF with and without ET, attenuates the vascular adaptation to ET, and elevates cardiac mitochondrial respiration. These data suggest that GLP-1 is integral to the adaptive vascular response to ET.

Quantification of Left Ventricular Shape Differentiates Pediatric Pulmonary Hypertension Subjects From Matched Controls

Changes in left ventricle (LV) shape are observed in patients with pulmonary hypertension (PH). Quantification of ventricular shape could serve as a tool to noninvasively monitor pediatric patients with PH. Decomposing the shape of a ventricle into a series of components and magnitudes will facilitate differentiation of healthy and PH subjects. Parasternal short-axis echo images acquired from 53 pediatric subjects with PH and 53 age and sex-matched normal control subjects underwent speckle tracking using Velocity Vector Imaging (Siemens) to produce a series of x,y coordinates tracing the LV endocardium in each frame. Coordinates were converted to polar format after which the Fourier transform was used to derive shape component magnitudes in each frame. Magnitudes of the first 11 components were normalized to heart size (magnitude/LV length as measured on apical view) and analyzed across a single cardiac cycle. Logistic regression was used to test predictive power of the method. Fourier decomposition produced a series of shape components from short-axis echo views of the LV. Mean values for all 11 components analyzed were significantly different between groups (p < 0.05). The accuracy index of the receiver operator curve was 0.85. Quantification of LV shape can differentiate normal pediatric subjects from those with PH. Shape analysis is a promising method to precisely describe shape changes observed in PH. Differences between groups speak to intraventricular coupling that occurs in right ventricular (RV) overload. Further analysis investigating the correlation of shape to clinical parameters is underway.

Development of an electrospun biomimetic polyurea scaffold suitable for vascular grafting

The optimization of biomechanical and biochemical properties of a vascular graft to render properties relevant to physiological environments is a major challenge today. These critical properties of a vascular graft not only regulate its stability and integrity, but also control invasion of cells for scaffold remodeling permitting its integration with native tissue. In this work, we have synthesized a biomimetic scaffold by electrospinning a blend of a polyurea, poly(serinol hexamethylene urea) (PSHU), and, a polyester, poly-ε-caprolactone (PCL). Mechanical properties of the scaffold were varied by varying polymer blending ratio and electrospinning flow rate. Mechanical characterization revealed that scaffolds with lower PSHU content relative to PCL content resulted in elasticity close to native mammalian arteries. We also found that increasing electrospinning flow rates also increased the elasticity of the matrix. Optimization of elasticity generated scaffolds that enabled vascular smooth muscle cells (SMCs) to adhere, grow and maintain a SMC phenotype. The 30/70 scaffold also underwent slower degradation than scaffolds with higher PSHU content, thereby, providing the best option for in vivo remodeling. Further, Gly-Arg-Gly-Asp-Ser (RGD) covalently conjugated to the polyurea backbone in 30/70 scaffold resulted in significantly increased clotting times. Reducing surface thrombogenicity by the conjugation of RGD is critical to avoiding intimal hyperplasia. Hence, biomechanical and biochemical properties of a vascular graft can be balanced by optimizing synthesis parameters and constituent components. For these reasons, the optimized RGD-conjugated 30/70 scaffold electrospun at 2.5 or 5 mL/h has great potential as a suitable material for vascular grafting applications. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 278-290, 2018.

A Zero-Dimensional Model and Protocol for Simulating Patient-Specific Pulmonary Hemodynamics From Limited Clinical Data

In pulmonary hypertension (PH) diagnosis and management, many useful functional markers have been proposed that are unfeasible for clinical implementation. For example, assessing right ventricular (RV) contractile response to a gradual increase in pulmonary arterial (PA) impedance requires simultaneously recording RV pressure and volume, and under different afterload/preload conditions. In addition to clinical applications, many research projects are hampered by limited retrospective clinical data and could greatly benefit from simulations that extrapolate unavailable hemodynamics. The objective of this study was to develop and validate a 0D computational model, along with a numerical implementation protocol, of the RV-PA axis. Model results are qualitatively compared with published clinical data and quantitatively validated against right heart catheterization (RHC) for 115 pediatric PH patients. The RV-PA circuit is represented using a general elastance function for the RV and a three-element Windkessel initial value problem for the PA. The circuit mathematically sits between two reservoirs of constant pressure, which represent the right and left atriums. We compared Pmax, Pmin, mPAP, cardiac output (CO), and stroke volume (SV) between the model and RHC. The model predicted between 96% and 98% of the variability in pressure and 98-99% in volumetric characteristics (CO and SV). However, Bland Altman plots showed the model to have a consistent bias for most pressure and volumetric parameters, and differences between model and RHC to have considerable error. Future studies will address this issue and compare specific waveforms, but these initial results are extremely promising as preliminary proof of concept of the modeling approach.

Enhancing Insights into Pulmonary Vascular Disease through a Precision Medicine Approach. A Joint NHLBI-Cardiovascular Medical Research and Education Fund Workshop Report

The Division of Lung Diseases of the NHLBI and the Cardiovascular Medical Education and Research Fund held a workshop to discuss how to leverage the anticipated scientific output from the recently launched "Redefining Pulmonary Hypertension through Pulmonary Vascular Disease Phenomics" (PVDOMICS) program to develop newer approaches to pulmonary vascular disease. PVDOMICS is a collaborative, protocol-driven network to analyze all patient populations with pulmonary hypertension to define novel pulmonary vascular disease (PVD) phenotypes. Stakeholders, including basic, translational, and clinical investigators; clinicians; patient advocacy organizations; regulatory agencies; and pharmaceutical industry experts, joined to discuss the application of precision medicine to PVD clinical trials. Recommendations were generated for discussion of research priorities in line with NHLBI Strategic Vision Goals that include: (1) A national effort, involving all the stakeholders, should seek to coordinate biosamples and biodata from all funded programs to a web-based repository so that information can be shared and correlated with other research projects. Example programs sponsored by NHLBI include PVDOMICS, Pulmonary Hypertension Breakthrough Initiative, the National Biological Sample and Data Repository for PAH, and the National Precision Medicine Initiative. (2) A task force to develop a master clinical trials protocol for PVD to apply precision medicine principles to future clinical trials. Specific features include: (a) adoption of smaller clinical trials that incorporate biomarker-guided enrichment strategies, using adaptive and innovative statistical designs; and (b) development of newer endpoints that reflect well-defined and clinically meaningful changes. (3) Development of updated and systematic variables in imaging, hemodynamic, cellular, genomic, and metabolic tests that will help precisely identify individual and shared features of PVD and serve as the basis of novel phenotypes for therapeutic interventions.

Errors in interpretation of neck levels in postoperative pathological specimens

Accurate orientation of pathological specimens is of fundamental importance, and specimens that are divided postoperatively may be misinterpreted. We asked surgeons and pathologists to identify boundaries between nodal levels on a clinical photograph of a neck dissection specimen. Few participants were able to identify the boundaries between levels accurately, with several important errors where a marked level contained none of the relevant anatomical tissue. Most errors were in level I, and the number decreased towards level IV. Errors were made by both pathologists and surgeons. The boundaries of level IIA were consistently overestimated, which may have implications for previous studies that evaluated patterns of nodal spread.

Hearing in school-aged children with trisomy 21 - results of a longitudinal cohort study in children identified at birth

OBJECTIVES

To report the prevalence of hearing problems and the hearing sequelae in school-aged children with trisomy 21 in a longitudinal study.

DESIGN

All children with trisomy 21 were identified via schools, community-based child development centres, general practitioners, or the universal newborn hearing screen. Audiological data and otorhinolaryngological problems were prospectively entered in to the Audiological Surveillance Programme database from each visit.

SETTING

Retrospective review of the Audiological Surveillance Programme database in the Glasgow area (United Kingdom) of all children reviewed between 2004 and 2012.

PARTICIPANTS

All pre-teenaged children with trisomy 21 of school age (aged 5-12 years old).

MAIN OUTCOME MEASURES

Hearing thresholds, aetiology of hearing loss and management of hearing loss was determined for the cohort of children.

RESULTS

A total of 102 children were included. Fifty-four had normal hearing. Twenty-six had fluctuating otitis media with effusion; five had hearing in normal limits, six were managed with hearing aids, fourteen were managed conservatively, and one had ventilation tube insertion. Fifteen had persistent otitis media with effusion; four had ventilation tube insertion; and nine were managed with hearing aids. Seven had mixed hearing loss with four required hearing aids.

CONCLUSIONS

Otitis media with effusion was the commonest cause of hearing impairment; effusions may fluctuate through the pre-teenaged years, and thus, hearing aids are beneficial. Ventilation tube insertion and bone-conducting hearing aids were useful when ear-level hearing aids were not tolerated. Mixed hearing loss occurred in later years as sensorineural hearing loss developed on a background of otitis media with effusion.

Non-invasive determination by cardiovascular magnetic resonance of right ventricular-vascular coupling in children and adolescents with pulmonary hypertension

BACKGROUND

Pediatric pulmonary hypertension (PH) remains a disease with high morbidity and mortality in children. Understanding ventricular-vascular coupling, a measure of how well matched the ventricular and vascular function are, may elucidate pathway leading to right heart failure. Ventricular vascular coupling ratio (VVCR), comprised of effective elastance (Ea, index of arterial load) and right ventricular maximal end-systolic elastance (Ees, index of contractility), is conventionally determined by catheterization. Here, we apply a non-invasive approach to determining VVCR in pediatric subjects with PH.

METHODS

This retrospective study included PH subjects who had a cardiovascular magnetic resonance (CMR) study within 14 days of cardiac catheterization. PH was defined as mean pulmonary artery pressure (mPAP) ≥ 25 mmHg on prior or current catheterization. A non-invasive measure of VVCR was derived from CMR-only (VVCRm) and compared to VVCR estimated by catheterization-derived single beat estimation (VVCRs). Indexed pulmonary vascular resistance (PVRi) and pulmonary vascular reactivity were determined during the catheterization procedure. Pearson correlation coefficients were calculated between PVRi and VVCRm. Receiver operating characteristic (ROC) curve analysis determined the diagnostic value of VVCRm in predicting vascular reactivity.

RESULTS

Seventeen subjects (3 months-23 years; mean 11.3 ± 7.4 years) were identified between January 2009-August 2013 for inclusion with equal gender distributions. Mean mPAP was 35 mmHg ± 15 and PVRi was 8.5 Woods unit x m2 ± 7.8. VVCRm (range 0.43-2.82) increased with increasing severity as defined by PVRi (p < 0.001), and was highly correlated with PVRi (r = 0.92, 95 % CI 0.79-0.97, p < 0.0001). Regression of VVCRm and PVRi demonstrated differing lines when separated by reactivity. VVCRm was significantly correlated with VVCRs (r = 0.79, CI 0.48-0.99, p <0.0001). ROC curve analysis showed high accuracy of VVCRm in determining vascular reactivity (VVCR = 0.85 had a sensitivity of 100 % and a specificity of 80 %) with an area under the curve of 0.89 (p = 0.008).

CONCLUSION

Measurement of VVCRm in pediatrics is feasible. Pulmonary vascular non-reactivity may be contribute to ventricular-vascular decoupling in severe PH. Therapeutic intervention to maintain a low vascular afterload in reactive patients may preserve right ventricular functional reserve and delay the onset of RV-PA decoupling. Use of VVCRm may have significant prognostic implication.

Investigating the effects of an oral fructose challenge on hepatic ATP reserves in healthy volunteers: A (31)P MRS study

BACKGROUND

Impaired homeostasis of hepatic ATP has been associated with NAFLD. An intravenous fructose infusion has been shown to be an effective challenge to monitor the depletion and subsequent recovery of hepatic ATP reserves using (31)P MRS.

AIMS

The purpose of this study was to evaluate the effects of an oral rather than intravenous fructose challenge on hepatic ATP reserves in healthy subjects.

METHODS

Self-reported healthy males were recruited. Following an overnight fast, baseline liver glycogen and lipid levels were measured using Magnetic Resonance Spectroscopy (MRS). Immediately after consuming a 500 ml 75 g fructose drink (1275 kJ) subjects were scanned continuously for 90 min to acquire dynamic (31)P MRS measurements of liver ATP reserves.

RESULTS

A significant effect on ATP reserves was observed across the time course (P < 0.05). Mean ATP levels reached a minimum at 50 min which was markedly lower than baseline (80 ± 17% baseline, P < 0.05). Subsequently, mean values tended to rise but did not reach statistical significance above minimum. The time to minimum ATP levels across subjects was negatively correlated with BMI (R(2) = 0.74, P < 0.005). Rates of ATP recovery were not significantly correlated with BMI or liver fat levels, but were negatively correlated with baseline glycogen levels (R(2) = 0.7, P < 0.05).

CONCLUSIONS

Depletion of ATP reserves can be measured non-invasively following an oral fructose challenge using (31)P MRS. BMI is the best predictor of postprandial ATP homeostasis following fructose consumption.