Arterial Hypertension and Unusual Ascending Aortic Dilatation in a Neonate With Acute Kidney Injury: Mechanistic Computer Modeling

Determinants of thoracic aortic size in normotensive and hypertensive individuals

AIMS

Thoracic aortic diameter is modulated by various factors including both physiological and pathological mechanisms. The aim of this study was to explore the determinants of thoracic aortic size focusing on arterial blood pressure and physical activity in normotensive and hypertensive individuals.

METHODS

Ascending and descending aortic diameters were measured in participants of the Copenhagen General Population Study using thoracic CT angiography. To assess the relation between arterial blood pressure and thoracic aortic diameters, individuals with diabetes, hypercholesterolemia, smoking, and prescribed antihypertensive medication were excluded. Intensity of physical activity was recorded based on self-reported questionnaire data.

RESULTS

A total of 1214 normotensive and 284 hypertensive individuals were examined. In all individuals, male sex, older age, and body surface area were associated with higher diameters of the ascending and descending aorta ( P  < 0.01). In normotensive individuals, hard physical activity > 4 h/week was independently associated with higher thoracic aortic diameters (ascending β:1.09[0.52;1.66] and descending β : 0.47[0.14;0.80], both P  < 0.01), whereas higher systolic blood pressure was not associated with thoracic aortic diameters (ascending P  = 0.12 and descending p  = 0.33). In hypertensive individuals, higher systolic blood pressure (per 10 mmHg) was independently associated with higher thoracic aortic diameters (ascending β : 0.55[0.17;0.94] and descending β : 0.23[0.10;0.37] mm/10 mmHg, both P  < 0.01), whereas hard physical activity was not associated with higher aortic diameters (ascending P  = 0.11 and descending P  = 0.51).

CONCLUSION

In normotensive individuals hard physical activity, and in hypertensive individuals increasing systolic blood pressure are factors each independently associated with larger thoracic aortic size. These findings suggest a context sensitive mode of aortic vascular response to size modulating adaptation.

Metabolic Syndrome Components and Its Impact on Acute Kidney Injury After Total Joint Arthroplasty

BACKGROUND

Metabolic syndrome (MetS) is an independent risk factor for postoperative complications. This study aimed to evaluate the associated risk of MetS for perioperative complications, especially urinary complications, in patients who underwent primary total knee arthroplasty (TKA) or total hip arthroplasty (THA).

METHODS

We used a publicly available all-payer administrative database to identify patients undergoing TKA and THA from 2016 to 2020. The primary exposure of interest was MetS. Multivariable adjusted models based on propensity score matching were used to evaluate the association of MetS components with acute kidney injury (AKI), urinary tract infection (UTI), and acute posthemorrhagic anemia (APHA) in patients who underwent TKA and THA. A counterfactual-based mediation analysis was conducted to investigate the mediating effect of APHA on the relationship between MetS and AKI.

RESULTS

The analysis included 2,097,940 (16.4% with MetS) THA and 3,073,310 (24.0% with MetS) TKA adult hospitalizations. Multivariable adjustment analysis indicated MetS was associated with an increased risk of AKI (odds ratio [OR] 1.78, 95% confidence interval [CI] 1.69 to 1.89 for THA; OR 1.88, 95% CI 1.79 to 1.96 for TKA), UTI (OR 1.13, 95% CI 1.03 to 1.23 for THA; OR 1.26, 95% CI 1.17 to 1.35 for TKA), and APHA (OR 1.17, 95% CI 1.14 to 1.20 for THA; OR 1.7, 95% CI 1.15 to 1.19 for TKA). The risk of AKI increased with the number of MetS components, with ORs ranging from 2.58 to 9.46 in TKA patients and from 2.22 to 5.75 in THA patients. This increase was particularly associated with diabetes and hypertension, which were the most significant associated risk factors. Furthermore, APHA mediated the association between MetS and AKI.

CONCLUSIONS

The prevalence of MetS is increasing in TKA and THA patients. Metabolic syndrome was associated with increased risk of AKI, UTI, and APHA. The risk of AKI increased with each additional MetS component, with diabetes and hypertension contributing most. In addition, APHA may play a partial mediating role in MetS-induced AKI.

Structure (Epicardial Stenosis) and Function (Microvascular Dysfunction) That Influence Coronary Fractional Flow Reserve Estimation

Background. The treatment of coronary stenosis is decided by performing high risk invasive surgery to generate the fractional flow reserve diagnostics index, a ratio of distal to proximal pressures in respect of coronary atherosclerotic plaques. Non-invasive methods are a need of the times that necessitate the use of mathematical models of coronary hemodynamic physiology. This study proposes an extensible mathematical description of the coronary vasculature that provides an estimate of coronary fractional flow reserve. Methods. By adapting an existing computational model of human coronary blood flow, the effects of large vessel stenosis and microvascular disease on fractional flow reserve were quantified. Several simulations generated flow and pressure information, which was used to compute fractional flow reserve under several conditions including focal stenosis, diffuse stenosis, and microvascular disease. Sensitivity analysis was used to uncover the influence of model parameters on fractional flow reserve. The model was simulated as coupled non-linear ordinary differential equations and numerically solved using our implicit higher order method. Results. Large vessel stenosis affected fractional flow reserve. The model predicts that the presence, rather than severity, of microvascular disease affects coronary flow deleteriously. Conclusions. The model provides a computationally inexpensive instrument for future in silico coronary blood flow investigations as well as clinical-imaging decision making. A combination of focal and diffuse stenosis appears to be essential to limit coronary flow. In addition to pressure measurements in the large epicardial vessels, diagnosis of microvascular disease is essential. The independence of the index with respect to heart rate suggests that computationally inexpensive steady state simulations may provide sufficient information to reliably compute the index.

Atrial Fibrillation and Anterior Cerebral Artery Absence Reduce Cerebral Perfusion: A De Novo Hemodynamic Model

Background: Atrial fibrillation is a prevalent cardiac arrhythmia and may reduce cerebral blood perfusion augmenting the risk of dementia. We hypothesize that geometric variations in the cerebral arterial structure called the Circle of Willis (CoW) play an important role in influencing cerebral perfusion. The objective of this work was to develop a novel cardio-cerebral lumped parameter hemodynamic model to investigate the role of CoW variants on cerebral blood flow dynamics under atrial fibrillation conditions. Methods: A computational blood flow model was developed by coupling whole-body and detailed cerebral circulation descriptions, modified to represent six common variations of the CoW. Cerebral blood flow dynamics were simulated in common CoW variants, under control and imposed atrial fibrillation conditions. Risk was assessed based on the frequency of beat-wise hypoperfusion events, and sensitivity analysis was performed with respect to this model output. Results: It was found that the geometry of the CoW influenced the frequency of hypoperfusion events at different heart rates, with the variant missing a P1 segment having the highest risk. Sensitivity analysis revealed that intrinsic heart rate is most associated with the considered outcome. Conclusions: Our results suggest that CoW geometry plays an important role in influencing cerebral hemodynamics during atrial fibrillation. The presented study may assist in guiding our future clinical-imaging research.

Using a Human Circulation Mathematical Model to Simulate the Effects of Hemodialysis and Therapeutic Hypothermia

Background: We developed a hemodynamic mathematical model of human circulation coupled to a virtual hemodialyzer. The model was used to explore mechanisms underlying our clinical observations involving hemodialysis. Methods: The model consists of whole body human circulation, baroreflex feedback control, and a hemodialyzer. Four model populations encompassing baseline, dialysed, therapeutic hypothermia treated, and simultaneous dialysed with hypothermia were generated. In all populations atrial fibrillation and renal failure as co-morbidities, and exercise as a treatment were simulated. Clinically relevant measurables were used to quantify the effects of each in silico experiment. Sensitivity analysis was used to uncover the most relevant parameters. Results: Relative to baseline, the modelled dialysis increased the population mean diastolic blood pressure by 5%, large vessel wall shear stress by 6%, and heart rate by 20%. Therapeutic hypothermia increased systolic blood pressure by 3%, reduced large vessel shear stress by 15%, and did not affect heart rate. Therapeutic hypothermia reduced wall shear stress by 15% in the aorta and 6% in the kidneys, suggesting a potential anti-inflammatory benefit. Therapeutic hypothermia reduced cardiac output under atrial fibrillation by 12% and under renal failure by 20%. Therapeutic hypothermia and exercise did not affect dialyser function, but increased water removal by approximately 40%. Conclusions: This study illuminates some mechanisms of the action of therapeutic hypothermia. It also suggests clinical measurables that may be used as surrogates to diagnose underlying diseases such as atrial fibrillation.

Animal, Human, and 23Na MRI Imaging Evidence for the Negative Impact of High Dietary Salt in Children

PURPOSE OF THE REVIEW

Conditions typically prevalent in adults such as hypertension, kidney stones, osteoporosis, and chronic kidney disease are increasing among adolescents and young adults (AYA). The purpose of this review is to describe the association of these conditions to a high salt diet among pediatric patients.

RECENT FINDINGS

We present animal, human, and 23Na MRI evidence associated with the negative impact of high dietary salt in children. Special focus is placed on novel 23Na MRI imaging which reveals the important concept of a third compartment for sodium storage in soft tissue. Finally, we make recommendations on who should not be on a low salt diet.

SUMMARY

A high salt intake predisposes children and AYA to considerable morbidity. We exhort the reader to engage in advocacy efforts to curve the incidence and prevalence of high salt-related life-limiting conditions.

An Interdisciplinary Approach to Optimize the Care of Transitioning Adolescents and Young Adults with CKD

Adolescents and young adults (AYAs) with CKD or end-stage kidney disease (ESKD) have unique medical, dental, psychosocial, neurocognitive, and academic needs and require close interdisciplinary collaboration to optimize their care. The etiology of CKD in AYAs is diverse compared to older adults. With their continuously improved survival, AYAs must start preparation for health-care transition (HCT) from pediatric- to adult-focused health care in the pediatric setting and it must continue at the adult-focused setting, given that their brain maturation and self-management skill acquisition occur until their mid-20s. While the growth and physical maturation of most visible body parts occur before 18 years of age, the prefrontal cortex of the brain, where reasoning, impulse control, and other higher executive functions reside, matures around 25 years of age. The HCT process must be monitored using patient- and caregiver-measuring tools to guide interventions. The HCT process becomes more complex when patients and/or caregivers have a language barrier, different cultural beliefs, or lower literacy levels. In this article, we discuss the unique comorbidities of pediatric-onset CKD/ESKD, provide information for a planned HCT preparation, and suggest interdisciplinary coordination as well as cultural and literacy-appropriate activities to achieve optimal patient outcomes.

Lower prevalence of aortic dilatation among preemptive pediatric renal transplant recipients - A cross-sectional cohort study

BACKGROUND

Aortic dilatation is a cardiovascular complication in pediatric renal transplant recipients and may have an increased risk of aortic dissection, aortic rupture, and death. Studies failed to show an association between blood pressure and aortic dilatation; however, 24-hours ambulatory blood pressure monitoring (ABPM) was not performed. There was also no comparison between preemptive transplantation and dialysis.

METHODS

After ethics approval, a retrospective cross-sectional study was performed on all prevalent pediatric renal transplant recipients from a single tertiary care center. The presence of aortic dilatation was determined using standard echocardiographic measurements, and those with other risk factors for aortic dilatation were excluded. Associations between 24-hours ABPM, renal function, dialysis history, and aortic dimensions were determined.

RESULTS

We enrolled 37 participants with the following characteristics: 46% female, mean age 14.5 ± 3.7 years, 16% preemptive transplantation, and median end-stage renal disease (ESRD) combined vintage (time from ESRD onset to echocardiogram) 597 days (range 289-1290 days). We found 16/37 patients (43%) with aortic dilatation at any level, mostly mild. There was no association between 24-hours ABPM measurements and aortic dilatation. None of the preemptively transplanted children had aortic dilatation.

CONCLUSION

This study confirms a high prevalence of aortic dilatation among pediatric renal transplant recipients, which appears to be independent of hypertension on 24-hour ABPM. Patients with preemptive renal transplantation did not have aortic dilatation, suggesting that the effects of dialysis may contribute to the high prevalence of this complication. Pediatric cardiologists need to carefully assess aortic dimensions in these at-risk patients.