Weight Lifting and Aortic Dissection: More Evidence for a Connection

Aortic root/left ventricular diameters golden ratio in competitive athletes

BACKGROUND

The athlete's heart is a well-known phenomenon characterized by a harmonic remodelling that affects the cardiac chambers. However, whether mild-to-moderate aortic dilatation can be considered normal in athletes is debated. This study aimed to evaluate the ratio between left ventricular (LV) size and aortic dimensions, reporting the normal values of the ratio between the aortic root diameters at the level of the sinuses of Valsalva and LV diameters (AoD/LVEDD ratio) in a wide cohort of competitive athletes.

MATERIALS AND METHODS

Competitive athletes were compared with sedentary subjects and patients with aortic dilatation. 1901 subjects who underwent echocardiography from 2019 to 2022 were retrospectively enrolled: 993 athletes (74% males, mean age 26 ± 7 years), 410 sedentary (74.1% males, mean age 29 ± 11 years) and 498 patients with aortic dilatation (74.3% males, mean age 56 ± 7 years).

RESULTS

Patients with aortic dilatation had both an absolute (39.2 ± 2.4 mm) and indexed (19.4 ± 2.2 mm/m2) aortic diameter larger than athletes (30.6 ± 3.2 mm; 16.1 ± 1.5 mm/m2, p < 0.05) and sedentary subjects (30.5 ± 3.1 mm; 16.5 ± 1.6 mm/m2, p < 0.05), with no differences between athletes and sedentary subjects. The AoD/LVEDD ratio was lower in athletes (0.59 ± 0.06) compared to controls (0.65 ± 0.05, p < 0.05) and patients with aortic dilatation (0.81 ± 0.06, p < 0.05). The patients with aortopathy had the lowest LVEDD/AoD ratio, while competitive athletes had the highest, with values of 1.71 ± 0.16 in the latter (overall p value<0.001).

CONCLUSIONS

In this study, we reported the AoD/LVEDD and LVEDD/AoD ratio values in a cohort of healthy athletes, additional parameters that could help confirm the harmonic remodelling in the athlete's heart.

Aortic Dissection in a Young Patient With Unsuspected Aortopathy

Aortic dissection is often a fatal condition if not recognized and treated emergently. Fortunately, it is extremely rare in children and adolescents. We report a case of an adolescent boy who survived an aortic dissection due to severe aortic root dilation. A comprehensive history and physical examination, including family history, can facilitate an early diagnosis of connective tissue diseases, such as Loeys-Dietz syndrome (LDS).

Aortic Root Diameter in Highly-Trained Competitive Athletes: Reference Values According to Sport and Prevalence of Aortic Enlargement

BACKGROUND

Studies exploring the extent of aortic root dilation across the different types of sport are limited. We aimed to define the physiological limits of aortic remodelling in a large population of healthy elite athletes in comparison with nonathletic controls.

METHODS

A total of 1995 consecutive athletes evaluated at the Institute of Sports Medicine (Rome, Italy) and 515 healthy controls underwent a comprehensive cardiovascular screening. The aortic diameter was measured at the level of the sinuses of Valsalva. The 99th percentile from the mean of the aortic diameter in the control population was used to define an abnormally enlarged aortic root dimension.

RESULTS

Athletes showed a larger aortic root diameter (30.6 [± 3.3] vs 28.1 [± 3.1] mm, P value < 0.001) than controls. The difference was evident in male and female athletes, regardless of sport- predominant component and level of intensity. The 99th percentile value for aortic root diameter in control male and female subjects was 37 mm and 32 mm, respectively. Based on these values, 50 (4.2%) male and 21 (2.6%) female athletes would have been diagnosed with an enlarged aortic root. However, aortic root diameter of clinical relevance-ie, ≥ 40 mm-was observed in only 17 male athletes (0.85%) and did not exceed > 44 mm.

CONCLUSIONS

Athletes show a mild, although significant, increased aortic dimension in comparison with healthy controls. The degree of aortic enlargement varies in relation to type of sports and sex. Eventually, only a small minority of athletes exhibited a markedly enlarged aortic diameter (ie, ≥ 40 mm) in a range of clinical relevance.

Chest and Thorax Injuries in Athletes

Injuries to the chest and thorax are rare, but when they occur, they can be life-threatening. It is important to have a high index of suspicion to be able to make these diagnoses when evaluating a patient with a chest injury. Often, sideline management is limited and immediate transport to a hospital is indicated.

Geometry and flow in ascending aortic aneurysms are influenced by left ventricular outflow tract orientation: Detecting increased wall shear stress on the outer curve of proximal aortic aneurysms

BACKGROUND

The geometrical characterization of ascending thoracic aortic aneurysms in clinical practice is limited to diameter measurements. Despite growing interest in hemodynamic assessment, its relationship with ascending thoracic aortic aneurysm pathogenesis is poorly understood. This study examines the relationship between geometry of the ventriculo-aortic junction and blood flow patterns in ascending thoracic aortic aneurysm disease.

METHODS

Thirty-three patients with ascending thoracic aortic aneurysms (exclusions: bicuspid aortic valves, connective tissue disease) underwent 4-dimensional flow magnetic resonance imaging. After image segmentation, geometrical parameters were measured, including aortic curvature, tortuosity, length, and diameter. A unique angular measurement made by the trajectory of the left ventricular outflow tract axis and the proximal aorta was also conducted. Velocity profiles were quantitatively and qualitatively analyzed. In addition, 11 patients (33%) underwent wall shear stress mapping of the ascending thoracic aortic aneurysm region using computational fluid dynamics simulation.

RESULTS

Greater left ventricular outflow tract aortic angles were associated with larger aortic diameters at the levels of the sinus (coefficient = 0.387, P = .014) and ascending aorta (coefficient = 0.284, P = .031). Patients with left ventricular outflow tract aortic angles greater than 60° had marked asymmetric flow acceleration on the outer curvature in the proximal aorta, ascertained from 4-dimensional flow analysis. For patients undergoing computational fluid dynamics assessment, regression analysis found that higher left ventricular outflow tract aortic angles were associated with significantly higher wall shear stress values in the outer curve of the aorta (coefficient 0.07, 95% confidence interval 0.04-0.11, P = .002): Angles greater than 50° yielded time-averaged wall shear stress values greater than 2.5 Pa, exhibiting a linear relationship.

CONCLUSIONS

Our findings strengthen the hypothesis of flow-mediated ascending thoracic aortic aneurysm disease progression and that left ventricular outflow tract aortic angle may be a predictor of disease severity.

Association of MLL3 and TGF-β signaling gene polymorphisms with the susceptibility and prognostic outcomes of Stanford type B aortic dissection : MLL3 with TGF-β signal pathway association with Stanford type B AD

OBJECTIVE

This study aims to investigate the association of lysine methyltransferase 2 C (MLL3) and transforming growth factor β (TGF-β) signaling-related gene polymorphisms with the susceptibility of Stanford type B aortic dissection (AD) and its clinical prognostic outcomes. The methods involved investigating the MLL3 (rs10244604, rs6963460, rs1137721), TGFβ1 (rs1800469), TGFβ2 (rs900), TGFR1 (rs1626340) and TGFR2 (rs4522809) gene polymorphisms. Logistic regression was performed to investigate the association between 7 single nucleotide gene polymorphisms (SNPs) and Stanford type B aortic dissection. The GMDR software was used to analyze gene-gene and gene-environment interactions. The odds ratio (OR) with a 95% confidence interval (CI) was employed to evaluate the association of genes and Stanford type B AD risk.

RESULTS

Genotypes and allele distributions in the case and control groups showed significant differences (P < 0.05). Logistic regression has shown that the Stanford Type B AD risk was highest in individuals with the rs1137721 CT genotype (OR = 4.33, 95% CI = 1.51-12.40). Additionally, WBC, drinking, hypertension, triglycerides (TG), and low-density lipoprotein (LDL-C) were independent risk factors for Stanford Type B AD. Logistic regression showed that the Stanford Type B AD risk was highest in individuals with the MLL3 (rs1137721)-TT + CT and TGFβ1 (rs4522809)-AA genotype (OR = 6.72, 95% CI = 1.56-29.84), and lowest in those with the MLL3 (rs1137721)-CC and TGFβ1 (rs4522809)-AA + GG genotype (OR = 4.38, 95% CI = 0.92-20.83). However, the 55-month median long-term follow-up did not show statistical significance.

CONCLUSION

Carriers of both TT + CT of MLL3 (rs1137721) and AA of TGFβ1 (rs4522809) polymorphisms may be closely related to the development of Stanford type B AD. MLL3 (rs1137721), WBC, and TG/TC were found to be associated with the morbidity of Stanford type B AD. MLL3 (KMT2C) is associated with the TGF-β signaling pathway protein. The risk of Stanford type B AD is related to the interactions of gene-gene and gene-environment.

Physiotherapy Screening for Referral of a Patient with Patent Foramen Ovale Presenting with Neck Pain as Primary Complaint: A Case Report

Neck pain is a common musculoskeletal disorder encountered by physiotherapists. However, it may be the early manifestation of more alarming conditions, such as cardiovascular diseases mimicking musculoskeletal pain. Patent foramen ovale (PFO) is a congenital heart defect consisting of a small opening between the right and the left atrium. A 56-year-old male presented with neck pain and head heaviness as primary complaints. The cardiovascular profile and the behavioral symptoms led the physiotherapist to find an exaggerated blood pressure response during exercise; in addition to subtle neurological signs, this prompted the physiotherapist to make an urgent referral. At the emergency department a PFO was diagnosed. To the best of the authors' knowledge, this is the first case to describe a rare clinical presentation of a PFO presenting neck pain as primary complaint. This case report emphasizes the importance for physiotherapists to be able to triage patients for conditions outside their scope suggestive of further medical investigation.

Nonsize Criteria for Surgical Intervention on the Ascending Thoracic Aorta

For decades, aortic surgery has relied on size criteria for intervention on the ascending aorta. While diameter has served well, diameter alone falls short of an ideal criterion. Herein, we examine the potential application of other, nondiameter criteria in aortic decision-making. These findings are summarized in this review. We have conducted multiple investigations of specific alternate nonsize criteria by leveraging our extensive database, which includes complete, verified anatomic, clinical, and mortality data on 2,501 patients with thoracic aortic aneurysm (TAA) and dissections (198 Type A, 201 Type B, and 2102 TAAs). We examined 14 potential intervention criteria. Each substudy had its own specific methodology, reported individually in the literature. The overall findings of these studies are presented here, with a special emphasis on how the findings can be incorporated into enhanced aortic decision-making-above and beyond sheer diameter. The following nondiameter criteria have been found useful in decision-making regarding surgical intervention. (1) Pain: In the absence of other specific cause, substernal chest pain mandates surgery. Well-developed afferent neural pathways carry warning signals to the brain. (2) Aortic length/tortuosity: Length is emerging as a mildly better predictor of impending events than diameter. (3) Genes: Specific genetic aberrations provide a powerful predictor of aortic behavior; malignant genetic variants obligate earlier surgery. (4) Family history: Aortic events closely follow those in relatives with a threefold increase in likelihood of aortic dissection for other family members once an index family dissection has occurred. (5) Bicuspid aortic valve: Previously thought to increase aortic risk (as a "Marfan light" situation), current data show that bicuspid valve is not a predictor of higher risk. (6) Diabetes actually protects against aortic events, via mural thickening and fibrosis. (7) Biomarkers: A specialized "RNA signature test" identifies aneurysm-bearing patients in the general population and promises to predict impending dissection. (8) Aortic stress: Blood pressure (BP) elevation from anxiety/exertion precipitates dissection, especially with high-intensity weightlifting. (9) Root dilatation imposes higher dissection risk than supracoronary ascending aneurysm. (10) Inflammation on positron emission tomography (PET) imaging implies high rupture risk and merits surgical intervention. (11) A KIF6 p.Trp719Arg variant elevates aortic dissection risk nearly two-fold. (12) Female sex confers some increased risk, which can be largely accommodated by using body-size-based nomograms (especially height nomograms). (13) Fluoroquinolones predispose to catastrophic dissection events and should be avoided rigorously in aneurysm patients. (14) Advancing age makes the aorta more vulnerable, increasing likelihood of dissection. In conclusion, nondiameter criteria can beneficially be brought to bear on the decision to observe or operate on specific TAA.

Collegiate Wrestler With a Bicuspid Aortic Valve and Aortic Dilation

Bicuspid aortic valve and aortopathy are generally considered contraindications to isometric exercise. For athletes with mild disease at low risk of adverse events, a shared decision-making approach for continued sports participation is reasonable. We present a case of a collegiate wrestler with bicuspid aortic valve and aortopathy to illustrate shared decision making. (Level of Difficulty: Intermediate.).

Does altitude increase the risk of traumatic aortic injuries? A retrospective cohort study among six level I trauma centers in the United States

Background

Traumatic aortic injuries (TAIs) are rare but are associated with a high mortality. Prior studies have shown skiers and pilots, whose injuries occur at high altitudes, are at an increased risk for a TAI. The purpose of this study was to examine the effect of altitude on the incidence of TAIs across all causes of injury.

Methods

This retrospective cohort study at six Level I trauma centers (8/1/2016–1/1/2020) included adult blunt trauma patients with a chest or abdomen injury. High altitude injuries (> 5000 ft.) were compared to low altitude injuries (≤ 5000 ft.). The primary outcome was incidence of TAI.

Results

There were 8562 patients, 37% were at high altitude and 63% at low altitude. High altitude patients were older (p < 0.01), more often Caucasian (p < 0.01) and had a higher ISS (p < 0.01). There was a significantly greater incidence of TAI at high altitude than low altitude (1.5% vs. 1.1%, p = 0.01). The median altitude was significantly higher for patients with a TAI than for patients without a TAI (5100 ft. vs. 1400 ft., p = 0.01). After adjustment, high altitude patients had 2-fold [OR: 2.4 (1.6, 3.7)] greater odds of having a TAI than low altitude patients.

Conclusion

TAIs were more prevalent among high altitude injuries. Providers should be aware of the increased incidence of TAIs at high altitudes particularly when there is a delay in diagnosis and transfer to a trauma center with appropriate resources to manage these critical injuries. TAI screening at high altitude trauma centers may improve survival rates.

Updated Blood Pressure Guidelines: Implications for Athletes

PURPOSE OF REVIEW

To review the prevalence, short- and long-term impact of exercise on blood pressure, and the evaluation and treatment of hypertension in competitive athletes.

RECENT FINDINGS

Due, in part, to inconsistencies in measurement and the definitions used, the true prevalence of hypertension is unknown as reports range from 0 to 83%. With recent changes in the blood pressure guidelines, the proportion of athletes that meet criteria for elevated blood pressure or stage 1 hypertension has increased dramatically with over one-third of collegiate and professional athletes meeting criteria for hypertension. Data consistently show that American-style football players, particularly linemen, display the highest rates of hypertension. These athletes typically have a larger body mass index, higher body fat percentage, and weight gain in serial follow-up. Many athletes with hypertension have traditional risk factors, and, to date, there is no evidence of a causal relationship between long-term sport participation and increased risk of developing hypertension. Many more athletes now meet criteria for hypertension, given the updated blood pressure guidelines. This should be taken as an opportunity for early intervention, as athletes are not immune to the development of cardiovascular risk factors and disease.

Is Exercise Blood Pressure Putting the Brake on Exercise Rehabilitation after Acute Type A Aortic Dissection Surgery?

(1) Background: Exercise is recommended to improve physical fitness in patients recovering from acute type A aortic dissection (ATAAD). However, surgery corrects the diseased blood vessels and reduces the risk of ATAAD, but it does not redefine a safe exercise blood pressure (BP) threshold. This review aimed to discuss whether the safe threshold of exercise BP can be upregulated after ATAAD surgery to increase exercise intensity with additional benefits. (2) Data sources: The PubMed databases were searched with the keywords “type A acute aortic dissection surgery”, “exercise”, “BP”, “stress”, and variations of these terms. (3) Study selection: Data from clinical trials, guidelines, and recent reviews were selected for review. (4) Results: Regular exercise can be considered a cardioprotective intervention for aortic dissection patients by attenuating hemodynamic responses at rest and during exercise. Previous studies have mainly focused on moderate-intensity aerobic exercise. In practice, the exercise systolic BP of some patients was higher than 160 mm Hg without adverse events, which indicates that the training intensity may be underestimated for patients after ATAAD surgery. Limited studies suggest a light-to-moderate resistance training for selected patients because it may cause a greater increase in BP. (5) Conclusions: Moderate-intensity continuous aerobic exercise supplemented by low-intensity resistance training is appropriate for cardiac rehabilitation after ATAAD surgery. The BP increase based on the normal exercise BP response, corresponding to the moderate-intensity is relatively safe. For high-risk post-ATAAD patients, considering the overall volume of training, personalizing the exercise regimen to remain within “safe” BP limits, and avoiding excessive fluctuations in BP should be the primary considerations for exercise training.

Association of gene polymorphisms in FBN1 and TGF-β signaling with the susceptibility and prognostic outcomes of Stanford type B aortic dissection

Background

This study is aimed at investigating the association of Fibrillin-1 (FBN1) and transforming growth factor β (TGF-β) signaling-related gene polymorphisms with the susceptibility of Stanford type B aortic dissection (AD) and its clinical prognostic outcomes.

Methods

Five single-nucleotide polymorphism (SNPs) (FBN1rs 145233125, rs201170905, rs11070646, TGFB1rs1800469, and TGFB2rs900) were analyzed in patients with Stanford type B AD (164) and healthy controls (317). Gene–gene and gene–environment interactions were assessed by generalized multifactor dimensionality reduction. A 4-year follow-up was performed for all AD patients.

Results

G carriers of FBN1 rs201170905 and TGFB1 rs1800469 have an increased risk of Stanford type B AD. The interaction of FBN1, TGFB1, TGFB2 and environmental promoted to the increased risk of type B AD (cross-validation consistency = 10/10, P = 0.001). Dominant models of FBN1rs145233125 TC + CC genotype (P = 0.028), FBN1 rs201170905 AG + GG (P = 0.047) and TGFB1 rs1800469 AG + GG (P = 0.052) were associated with an increased risk of death of Stanford type B AD. The recessive model of FBN1 rs145233125 CC genotype (P < 0.001), FBN1rs201170905 GG (P < 0.001), TGFB1 rs1800469 AG + GG genotype (P = 0.011) was associated with an increased risk of recurrence of chest pain in Stanford type B AD.

Conclusions

The interactions of gene–gene and gene–environment are related with the risk of Stanford type B AD. C carriers of rs145233125, G carriers of rs201170905 and G carriers of rs1800469 may be the poor clinical outcome indicators of mortality and recurrent chest pain in Stanford type B AD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01213-z.

Once after a full moon: acute type A aortic dissection and lunar phases

OBJECTIVES

Acute type A aortic dissection (ATAAD) is a rare but severe condition, routinely treated with emergent cardiac surgery. Many surgeons have the notion that patients with ATAAD tend to come in clusters, but no studies have examined these observations. This investigation was undertaken to study the potential association between the lunar cycle and the incidence of ATAAD.

METHODS

We collected information on 2995 patients who underwent ATAAD surgery at centres from the Nordic Consortium for Acute Type A Aortic Dissection collaboration. We cross-referenced the time of surgery with lunar phase using a case-crossover design with 2 different definitions of full moon (>99% illumination and the 7-day full moon period).

RESULTS

The period when the moon was illuminated the most (99% definition) did not show any significant increase in incidence for ATAAD surgery. However, when the full moon period was compared with all other moon phases, it yielded a relative risk of 1.08 [95% confidence interval (CI) 1.00-1.17, P = 0.057] and, compared to waxing moon, only the relative risk was 1.11 (95% CI 1.01-1.23, P = 0.027). The peak incidence came 4-6 days after the moon was fully illuminated.

CONCLUSIONS

This study found an overrepresentation of surgery for ATAAD during the full moon phase. The explanation for this is not known, but we speculate that sleep deprivation during full moon leads to a temporary increase in blood pressure, which in turn could trigger rupture of the aortic wall. While this finding is interesting, it needs to be corroborated and the clinical implications are debateable.

Changes in aortic collagen in β-aminopropionitrile-induced acute aortic dissection

Background

The precise role collagen plays in acute aortic dissection (AAD) was investigated in an animal model of β-aminopropinitrile (BAPN)-induced AAD.

Methods

The 30 3-week-old male specific-pathogen free (SPF)-grade Sprague-Dawley (SD) rats were randomly divided into two groups: 10 in the Control group and 20 in the Model group. The Model group was treated with 0.1% BAPN for 4 weeks, while the Control group received untreated water. Histopathological staining and western blot were used to detect changes of the extracellular matrix (ECM) and collagen content in the aorta.

Results

At the end of the experiment, the incidence of AAD was 25%, the aortic ECM of surviving rats was severely damaged, and the arrangement was disordered. Fibroblast cells are unevenly distributed, with wide gaps, collagen fibers were also distributed unevenly in a disordered arrangement and their thickness was uneven. The elastic membrane disappeared over a large area. Compare to Control group, the Collagen types I, III and their subunits were upregulated (P<0.05), while matrix metalloproteinase (MMP) 2 and MMP9 were downregulated in the aorta of Model group (P<0.05).

Conclusions

In the animal model of BAPN-induced AAD, collagen types I, III and subunits were increased, while MMP2 and MMP9 were decreased in thoracic aorta, which may lead to stiffness of the aorta and be the cause of dissection.

The impact of pre-existing blood pressure control in patients with acute aortic dissections

OBJECTIVES

Arterial hypertension (HTN) is considered a seminal risk factor for aortic dissection (AD). The purpose of this study is to evaluate whether pre-existing blood pressure (BP) control lessens the extent of dissection and has a favorable impact on outcome of patients with acute AD.

METHODS

Consecutive acute AD patients who had at least two BPs recorded within the 12 months preceding the AD were retrospectively analyzed. The two most recent BPs were averaged and defined per published guidelines as normal (BP≤ 130/80), Stage I HTN (BP >130/80 and <139/89), or Stage 2 or greater HTN (BP > 140/90). The number of hypertensive medications (MEDs) was also used as a surrogate marker of HTN severity. Patients with known genetic causes of AD were excluded.

RESULTS

89 subjects (55% men, 45% women; mean age, 64±14 years) with acute AD (58% Stanford type A and 42% Stanford type B) were included. Two most recent BPs were recorded a mean of 5±3 and 3±2.7 months before the AD, respectively. Twenty-nine (33%) subjects had normal BP, including nine subjects with no history of HTN and on no MEDs. Sixty (67%) subjects had elevated BP, including 21 (35%) with Stage I HTN and 39 (65%) with Stage 2 HTN. Compared to subjects with normal BP, subjects with Stage 1 and Stage 2 HTN were younger (70±13 years vs 62±1 year, p = 0.01), but there were no differences in other demographics, risk factors, comorbidities, or history of drug use. There were no group differences in the distal extent of the dissections, complications requiring thoracic endograft repair, mean length of hospital stay, final discharge status, or 30-day mortality. Compared to the number of MEDs before AD, all three groups had a higher mean number of MEDs to achieve normal BP at discharge that persisted at a mean follow-up of 18±15 months.

CONCLUSIONS

These data show that approximately one-third of patients with acute AD had well controlled or no antecedent history of HTN. The degree of pre-existing HTN control had no bearing on the type or extent of AD, length of stay, or early outcome. Regardless of the state of HTN control before AD, the consistent and sustained increase in the severity of HTN after AD suggests that the dissection process has a profound and lasting effect on BP regulation. Further studies are indicated to elucidate the pathologic mechanisms involved in AD.

Straight back syndrome as a clue to diagnosing asymptomatic congenital valvular heart disease and limiting the risk of weightlifting

Although both are initially asymptomatic, mitral valve prolapse/myxomatous mitral valve disease (MVP/MMVD) and bicuspid aortic valve (BAV), with its associated aortic disease, are currently the two most common congenital valvular heart diseases. Severe mitral regurgitation due to rupture of chordae tendineae (CTR) prompts surgery for MVP/MMVD. Surgery for BAV is performed for severe aortic stenosis and/or regurgitation, often with management of root and/or ascending aortic enlargement. There may be an association between straight back syndrome (SBS) and MVP/MMVD, which may be a key to earlier diagnosis. Other associations link weightlifting with ascending aortic enlargement and with CTR, where the common theme is blood pressure elevation. As the number of people with fitness center memberships continues to increase, this potentially exposes more undiagnosed individuals with MVP/MMVD or BAV to risk from weightlifting. Challenges include making the public aware of this risk and preparing the osteopathic physician to recognize patients at risk through a structured history-taking and targeted cardiovascular examination.

Computation of a probabilistic and anisotropic failure metric on the aortic wall using a machine learning-based surrogate model

Scalar-valued failure metrics are commonly used to assess the risk of aortic aneurysm rupture and dissection, which occurs under hypertensive blood pressures brought on by extreme emotional or physical stress. To compute failure metrics under an elevated blood pressure, a classical patient-specific computer model consists of multiple computation steps involving inverse and forward analyses. These classical procedures may be impractical for time-sensitive clinical applications that require prompt feedback to clinicians. In this study, we developed a machine learning-based surrogate model to directly predict a probabilistic and anisotropic failure metric, namely failure probability (FP), on the aortic wall using aorta geometries at the systolic and diastolic phases. Ascending thoracic aortic aneurysm (ATAA) geometries of 60 patients were obtained from their CT scans, and biaxial mechanical testing data of ATAA tissues from 79 patients were collected. Finite element simulations were used to generate datasets for training, validation, and testing of the ML-surrogate model. The testing results demonstrated that the ML-surrogate can compute the maximum FP failure metric, with 0.42% normalized mean absolute error, in 1 s. To compare the performance of the ML-predicted probabilistic FP metric with other isotropic or deterministic metrics, a numerical case study was performed using synthetic "baseline" data. Our results showed that the probabilistic FP metric had more discriminative power than the deterministic Tsai-Hill metric, isotropic maximum principal stress, and aortic diameter criterion.

Cardiopulmonary Exercise Testing Following Open Repair for a Proximal Thoracic Aortic Aneurysm or Dissection

PURPOSE

There are limited data on cardiopulmonary exercise testing (CPX) and cardiorespiratory fitness (CRF), following open repair for a proximal thoracic aortic aneurysm or dissection. The aim was to evaluate serious adverse events, abnormal CPX event rate, CRF (peak oxygen uptake, (Equation is included in full-text article.)O2peak), and blood pressure.

METHODS

Patients were retrospectively identified from cardiac rehabilitation participation or prospectively enrolled in a research study and grouped by phenotype: (1) bicuspid aortic valve/thoracic aortic aneurysm, (2) tricuspid aortic valve/thoracic aortic aneurysm, and (3) acute type A aortic dissection.

RESULTS

Patients (n = 128) completed a CPX a median of 2.9 mo (interquartile range: 1.8, 3.5) following repair. No serious adverse events were reported, although 3 abnormal exercise tests (2% event rate) were observed. Eighty-one percent of CPX studies were considered peak effort (defined as respiratory exchange ratio of ≥1.05). Median measured (Equation is included in full-text article.)O2peak was <36% predicted normative values (19.2 mL·kgmin vs 29.3 mLkgmin, P < .0001); the most marked impairment in (Equation is included in full-text article.)O2peak was observed in the acute type A aortic dissection group (<40% normative values), which was significantly different from other groups (P < .05). Peak exercise systolic and diastolic blood pressures were 160 mm Hg (144, 172) and 70 mm Hg (62, 80), with no differences noted between groups.

CONCLUSIONS

We observed no serious adverse events with an abnormal CPX event rate of only 2% 3 mo following repair for a proximal thoracic aortic aneurysm or dissection. (Equation is included in full-text article.)O2peak was reduced among all patient groups, especially the acute type A aortic dissection group, which may be clinically significant, given the well-established prognostic importance of reduced cardiorespiratory fitness.

Cervical Artery Dissection and Sports

Cervical artery dissection (CeAD) occurring in the context of sports is a matter of concern for CeAD patients. They seek advice on the role of sports in CeAD and on the safety of resuming sports after CeAD. The scarcity of studies and guidelines addressing these issues poses a challenge. We aimed at summarizing the current knowledge about CeAD and sports in order to provide an informed, comprehensive opinion for counseling CeAD patients. We took into account pathophysiological considerations, observations of cases reports, series, and registries, and conclusions by analogy from aortic dissection or inherited connective tissue syndromes. In summary, practicing active sports as the cause of CeAD seems uncommon. It seems recommendable to refrain from any kind of sports activities for at least 1 month, which can be extended in case of an unfavorable clinical or neurovascular course. We recommend starting with sport activities at low intensity—preferably with types of endurance sports—and to gradually increase the pace in an individually tailored manner, taking into circumstances of the occurrences of the CeAD in the individual patient (particularly in relation to sports), the meaning of sports activities for the individual well-being, the presence or absence of comorbidities and of neurological sequela, neurovascular findings, and whether there are signs of an underlying connective tissue alteration. Major limitations and several forms of bias are acknowledged. Still, in the absence of any better data, the summarized observations and considerations might help clinicians in advising and counseling patients with CeAD in clinical practice.

Physical activities and surgical outcomes in elderly patients with acute type A aortic dissection

OBJECTIVE

Although elderly patients undergoing surgery for acute type A aortic dissection (ATAAD) is increasing, their physical activities are not fully understood. We report the physical activities and surgical outcomes in elderly patients who underwent ATAAD.

METHODS

From 2009 to 2019, 103 consecutive patients underwent surgery for ATAAD at our institution. Surgical outcomes along with pre- and postoperative physical activities in 52 elderly patients (≥70 years old) were compared with those in 51 younger patients (<70 years old). Postoperative walking difficulty was defined as taking ≥30 days to regain the ability to walk 200 m postoperatively or as the inability to walk at discharge.

RESULTS

It took longer for elderly patients to regain the ability to walk 100 or 200 m postoperatively. ROC analysis revealed the AUC of the duration for walking 200 m postoperatively as a prognostic indicator for late deaths was 0.878, with the highest accuracy at 30 days (sensitivity = 83.3%, specificity = 91.8%). Hospital mortality within 30 days was 3.8%, and 1-, 3-, and 5-years survival rates were 92%, 84.7%, 84.7%, respectively, for elderly patients, with no significant differences between groups. Cox proportional hazard analysis showed postoperative walking difficulty was an independent risk factor for late mortality in all cohorts (p = .017).

CONCLUSIONS

Elderly patients undergoing surgical ATAAD repair showed acceptable surgical outcomes. However, they were more likely to decrease their physical activities postoperatively. Postoperative difficulty in walking was an independent risk factor for the late mortality in patients with ATAAD.

A Parametric Study on Factors Influencing the Onset and Propagation of Aortic Dissection Using the Extended Finite Element Method

OBJECTIVE

Aortic dissection is a life-threatening event which starts most of the time with an intimal tear propagating along the aortic wall, while blood enters the medial layer and delaminates the medial lamellar units. Studies investigating the mechanisms underlying the initiation sequence of aortic dissection are rare in the literature, the majority of studies being focused on the propagation event. Numerical models can provide a deeper understanding of the phenomena involved during the initiation and the propagation of the initial tear, and how geometrical and mechanical parameters affect this event. In the present paper, we investigated the primary factors contributing to aortic dissection.

METHODS

A two-layer arterial model with an initial tear was developed, representing three different possible configurations depending on the initial direction of the tear. Anisotropic damage initiation criteria were developed based on uniaxial and shear experiments from the literature to predict the onset and the direction of crack propagation. We used the XFEM-based cohesive segment method to model the initiation and the early propagation of the tear along the aorta. A design of experiment was used to quantify the influence of 7 parameters reflecting crack geometry and mechanics of the wall on the critical pressure triggering the dissection and the directions of propagation of the tear.

RESULTS

The results showed that the obtained critical pressures (mean range from 206 to 251 mmHg) are in line with measurement from the literature. The medial tensile strength was found to be the most influential factor, suggesting that a medial degeneration is needed to reach a physiological critical pressure and to propagate a tear in an aortic dissection. The geometry of the tear and its location inside the aortic wall were also found to have an important role not only in the triggering of tear propagation, but also in the evolution of the tear into either aortic rupture or aortic dissection. A larger and deeper initial tear increases the risk of aortic dissection.

CONCLUSION

The numerical model was able to reproduce the behaviour of the aorta during the initiation and propagation of an aortic dissection. In addition to confirm multiple results from the literature, different types of tears were compared and the influence of several geometrical and mechanical parameters on the critical pressure and direction of propagation was evaluated with a parametric study for each tear configuration.

SIGNIFICANCE

Although these results should be experimentally validated, they allow a better understanding of the phenomena behind aortic dissection and can help in improving the diagnosis and treatment of this disease.

Factors mediating the pressor response to isometric muscle contraction: An experimental study in healthy volunteers during lower body negative pressure

Whilst both cardiac output (CO) and total peripheral resistance (TPR) determine mean arterial blood pressure (MAP), their relative importance in the pressor response to isometric exercise remains unclear. This study aimed to elucidate the relative importance of these two different factors by examining pressor responses during cardiopulmonary unloading leading to step-wise reductions in CO. Hemodynamics were investigated in 11 healthy individuals before, during and after two-minute isometric exercise during lower body negative pressure (LBNP; -20mmHg and -40mmHg). The blood pressure response to isometric exercise was similar during normal and reduced preload, despite a step-wise reduction in CO during LBNP (-20mmHg and -40mmHg). During -20mmHg LBNP, the decreased stroke volume, and consequently CO, was counteracted by an increased TPR, while heart rate (HR) was unaffected. HR was increased during -40 mmHg LBNP, although insufficient to maintain CO; the drop in CO was perfectly compensated by an increased TPR to maintain MAP. Likewise, transient application of LBNP (-20mmHg and -40mmHg) resulted in a short transient drop in MAP, caused by a decrease in CO, which was compensated by an increase in TPR. This study suggests that, in case of reductions of CO, changes in TPR are primarily responsible for maintaining the pressor response during isometric exercise. This highlights the relative importance of TPR compared to CO in mediating the pressor response during isometric exercise.

Diagnostic approach and management of genetic aortopathies

Aortic aneurysms were the primary cause of nearly 10,000 deaths in 2014 according to data from the Centers for Disease Control and may involve segments of the thoracic or abdominal aorta. Thoracic aortic aneurysms and dissections are more commonly associated with an underlying genetic etiology. In the past several decades, in parallel with the burst of new genome sequencing technologies, a number of genetic aortopathies have been identified. These have provided important insights into the molecular mechanisms of aneurysmal disease, but pose challenges in clinical practice as there are limited consensus recommendations at this time. In this review, we aim to address the pathophysiology, clinical presentation, and treatment considerations in the key heritable thoracic aortopathies.

Blood Pressure Increase in Hypertensive Individuals During Resistance Training Protocols With Equated Work to Rest Ratio

Introduction: Despite growing evidence regarding the benefits of resistance training in hypertension, the large and abrupt rise of systolic blood pressure (SBP) observed during resistance exercise execution has resulted in concern about its safety. However, the manipulation of the resistance training protocol (RTP) organization, maintaining the work to rest ratio equated between protocols (W:R-equated), may reduce the SBP increase.

Purpose: To compare cardiovascular responses during two W:R-equated RTPs (3 × 15:88 s vs. 9 × 5:22 s – sets × reps: rest between sets) performed in exercises for the lower and upper limbs.

Methods: Twelve medicated hypertensives (48 ± 8 years) randomly performed two RTPs in the bilateral leg extension (BLE) and unilateral elbow flexion (UEF) exercises at 50% 1RM. Increases (Δ) of SBP, heart rate (HR) and rate pressure product (RPP) during the exercises were measured by photoplethysmography.

Results: In both BLE and UEF exercises, Δ SBP was significantly greater during 3 × 15:88 s than 9 × 5:22 s (peak values: BLE = + 84 ± 39 vs. + 67 ± 20 mm Hg, and UEF = + 46 ± 25 vs. + 37 ± 18 mm Hg, respectively, both p < 0.05). ΔHR and ΔRPP were significantly higher in the 3 × 15:88 s than 9 × 5:22 s in BLE (peak values + 45 ± 17 vs. + 30 ± 8 bpm, and + 15,559 ± 5570 vs. + 10,483 ± 2614 mm Hg. bpm).

Conclusion: In medicated hypertensives, a RTP combining more sets with less repetitions per set and shorter rest intervals between sets (i.e., 9 × 5:22 s) produced a smaller increase in cardiovascular load (ΔSBP, ΔHR and ΔRPP) during its execution than a protocol with fewer longer sets (i.e., 3 × 15:88 s).

Acceleration-induced acute type A aortic dissection in the sky: 10-year follow-up

Acute aortic dissection is uncommon, but can turn into a fatal disease if not managed quickly. A 49-year-old male fighter pilot presented to us after sudden excruciating chest pain during a flight at the moment of an acute spiral down action. A contrast-enhanced computed tomography angiography showed Stanford type A aortic dissection that required surgical ascending aorta and hemiarch replacement with uneventful postoperative recovery and 10-year follow-up. Here, we presented the first report of a previously healthy pilot developed acute aortic dissection in the sky. Physicians should be aware of such a case that might happen more common with rapid aviation progress.

Exercise-Related Acute Cardiovascular Events and Potential Deleterious Adaptations Following Long-Term Exercise Training: Placing the Risks Into Perspective-An Update: A Scientific Statement From the American Heart Association

Epidemiological and biological plausibility studies support a cause-and-effect relationship between increased levels of physical activity or cardiorespiratory fitness and reduced coronary heart disease events. These data, plus the well-documented anti-aging effects of exercise, have likely contributed to the escalating numbers of adults who have embraced the notion that "more exercise is better." As a result, worldwide participation in endurance training, competitive long distance endurance events, and high-intensity interval training has increased markedly since the previous American Heart Association statement on exercise risk. On the other hand, vigorous physical activity, particularly when performed by unfit individuals, can acutely increase the risk of sudden cardiac death and acute myocardial infarction in susceptible people. Recent studies have also shown that large exercise volumes and vigorous intensities are both associated with potential cardiac maladaptations, including accelerated coronary artery calcification, exercise-induced cardiac biomarker release, myocardial fibrosis, and atrial fibrillation. The relationship between these maladaptive responses and physical activity often forms a U- or reverse J-shaped dose-response curve. This scientific statement discusses the cardiovascular and health implications for moderate to vigorous physical activity, as well as high-volume, high-intensity exercise regimens, based on current understanding of the associated risks and benefits. The goal is to provide healthcare professionals with updated information to advise patients on appropriate preparticipation screening and the benefits and risks of physical activity or physical exertion in varied environments and during competitive events.

Particle-based computational modelling of arterial disease

Accumulated glycosaminoglycans (GAGs) can sequester water and induce swelling within the intra-lamellar spaces of the medial layer of an artery. It is increasingly believed that stress concentrations caused by focal swelling can trigger the damage and delamination that is often seen in thoracic aortic disease. Here, we present computational simulations using an extended smoothed particle hydrodynamics approach to examine potential roles of pooled GAGs in initiating and propagating intra-lamellar delaminations. Using baseline models of the murine descending thoracic aorta, we first calculate stress distributions in a healthy vessel. Next, we examine increases in mechanical stress in regions surrounding GAG pools. The simulations show that smooth muscle activation can partially protect the wall from swelling-associated damage, consistent with experimental observations, but the wall can yet delaminate particularly in cases of smooth muscle dysfunction or absence. Moreover, pools of GAGs located at different but nearby locations can extend and coalesce, thus propagating a delamination. These findings, combined with a sensitivity study on the input parameters of the model, suggest that localized swelling can alter aortic mechanics in ways that eventually can cause catastrophic damage within the wall. There is, therefore, an increased need to consider roles of GAGs in aortic pathology.

The American Association for Thoracic Surgery consensus guidelines on bicuspid aortic valve-related aortopathy: Full online-only version

Bicuspid aortic valve disease is the most common congenital cardiac disorder, being present in 1% to 2% of the general population. Associated aortopathy is a common finding in patients with bicuspid aortic valve disease, with thoracic aortic dilation noted in approximately 40% of patients in referral centers. Several previous consensus statements and guidelines have addressed the management of bicuspid aortic valve-associated aortopathy, but none focused entirely on this disease process. The current guidelines cover all major aspects of bicuspid aortic valve aortopathy, including natural history, phenotypic expression, histology and molecular pathomechanisms, imaging, indications for surgery, surveillance, and follow-up, and recommendations for future research. It is intended to provide clinicians with a current and comprehensive review of bicuspid aortic valve aortopathy and to guide the daily management of these complex patients.

Fluoroquinolones and Aortic Diseases: Is There a Connection

Fluoroquinolones (FQs) are one of the most commonly prescribed classes of antibiotics. Their high tissue distribution and broad-spectrum antibacterial coverage make their use very attractive in numerous infectious diseases. Although generally well tolerated, FQs have been associated with different adverse effects including dysglycemia and arrhythmias. FQs have been also associated with a series of adverse effects related to collagen degradation, such as Achilles tendon rupture and retinal detachment. Recently, an association between consumption of FQs and increased risk of aortic aneurysm and dissection has been proposed. This article reviews the pathogenesis of thoracic aortic diseases, the molecular mechanism of FQ-associated collagen toxicity, and the possible contribution of FQs to aortic diseases.

The American Association for Thoracic Surgery consensus guidelines on bicuspid aortic valve-related aortopathy: Executive summary

Bicuspid aortic valve disease is a common congenital cardiac disorder, being present in 1% to 2% of the general population. Associated aortopathy is a common finding in patients with bicuspid aortic valve disease, with thoracic aortic dilation noted in approximately 40% of patients in referral centers. Several previous consensus statements and guidelines have addressed the management of bicuspid aortic valve-associated aortopathy, but none focused entirely on this disease process. The current document is an executive summary of "The American Association for Thoracic Surgery Guidelines on Bicuspid Aortic Valve-Related Aortopathy." All major aspects of bicuspid aortic valve aortopathy, including natural history, phenotypic expression, histology and molecular pathomechanisms, imaging, indications for surgery, surveillance, and follow-up, and recommendations for future research are contained within these guidelines. The current executive summary serves as a condensed version of the guidelines to provide clinicians with a current and comprehensive review of bicuspid aortic valve aortopathy and to guide the daily management of these complex patients.

Blood Pressure Response During Resistance Training of Different Work-to-Rest Ratio

Paulo, AC, Tricoli, V, Queiroz, ACC, Laurentino, G, and Forjaz, CLM. Blood pressure response during resistance training of different work-to-rest ratio. J Strength Cond Res 33(2): 399-407, 2019-Changes in the work-to-rest ratio (W:R) of resistance training protocols (RTPs) (i.e., decreasing work or increasing rest) reduce the marked elevation in blood pressure (BP) that occurs during RTP execution. However, whether changes in RTP structure without changing W:R can change BP responses to RTP is unknown. To investigate the effect of different structures of rest intervals and number of repetitions per set on BP response among RTP equated and nonequated for W:R, 20 normotensive participants (25 ± 4 years) performed 4 different RTP of the leg extension exercise with the same work but different W:R structures. Two protocols followed the recommendations for cardiovascular disorders: (a) HIGHW:R-3×15:44s-3×15:44s (set×reps:rest between sets), which has high W:R (45reps:88s) and (b) LOWW:R-3×15:88s-3×15:88s, which has low W:R (45reps:176s). The other 2 protocols were W:R-equated to LOWW:R (45reps:176s): (c) LOWW:R-9×5:22s and (d) LOWW:R-45×1:4s. Systolic BP (ΔSBP) and diastolic BP (ΔDBP) were assessed by finger photoplethysmography. There were significant main effects for ΔSBP after RTP (p ≤ 0.05): HIGHW:R-3×15:44s = LOWW:R-3×15:88s > LOWW:R-45×1:4s > LOWW:R-9×5:22s (+87 ± 5 and +84 ± 5 vs. +61 ± 4 vs. 57 ± 4 mm Hg). For ΔDBP, there was a significant interaction between RTP and moment (p ≤ 0.05). Thus, HIGHW:R-3×15:44 > LOWW:R-3×15:88s > LOWW:R-45×1:4s > LOWW:R-9×5:22s (+53 ± 5 vs. +49 ± 5 vs. +44 ± 4 vs. +38 ± 3 mm Hg). HIGHW:R-3×15:44s produced the highest increase in ΔDBP, and LOWW:R-9×5:22s produced the lowest increase in ΔSBP and ΔDBP. Our findings may help the development of RTP protocols that may mitigate pressure peaks without changing important exercise variables (i.e., volume or duration).

Experimental Insight into the Hemodynamics and Perfusion of Radiological Contrast in Patent and Non-patent Aortic Dissection Models

PURPOSE

In a curved vessel such as the aortic arch, the velocity profile closer to the aortic root is normally skewed towards the inner curvature wall, while further downstream along the curve, the velocity profile becomes skewed towards the outer wall. In an aortic dissection (AD) disease, blood velocities in the true lumen (TL) and false lumen (FL) are hypothesized to depend on the proximity of the entry tear to the root of aortic arch. Faster velocity in the FL can lead to higher hemodynamic loading, and pose tearing risk. Furthermore, the luminal velocities control the perfusion rate of radiological contrast media during diagnostic imaging. The objective in this study is to investigate the effect of AD disease morphology and configuration on the blood velocity field in the TL and FL, and on the relative perfusion of radiological enhancement agents through the dissection.

METHODS

Eight in vitro models were studied, including patent and non-patent FL configurations. Particle image velocimetry (PIV) was used to quantify the AD velocity field, while laser-induced fluorescence (LIF) was implemented to visualize dynamical flow phenomena and to quantify the perfusion of injected dye, in mimicry of contrast-enhanced computed tomography (CT).

RESULTS

The location of the proximal entry tear along the aortic arch in a patent FL had a dramatic impact on whether the blood velocity was higher in the TL or FL. The luminal velocities were dependent on the entry/reentry tear size combination, with the smaller tear (whether distal or proximal) setting the upper limit on the maximal flow velocity in the FL. Upon merging near the distal reentry tear, the TL/FL velocity differential gave rise to the roll up and shedding of shear layer vortices that convected downstream in close proximity to the wall of the non-dissected aorta. In a non-patent FL, the flow velocity was practically null with all the blood passing through the TL. LIF imaging showed much slower perfusion of contrast dye in the FL compared to the TL. In a patent FL, however, dye had a comparable perfusion rate appearing around the same time as in the TL.

CONCLUSIONS

Blood velocities in the TL and FL were highly sensitive to the exact dissection configuration. Geometric case A1R, which had its proximal entry tear located further downstream along the aortic arch, and had its entry and reentry tears sufficiently sized, exhibited the highest FL flow velocity among the tested models, and it was also higher than in the TL, which suggest that this configuration had elevated hemodynamic loading and risk for tearing. In contrast-enhanced diagnostic imaging, a time-delayed acquisition protocol is recommended to improve the detection of suspected cases with a non-patent FL.

Spontaneous Infrarenal Aortic Dissection in an Athlete Managed Emergently With Endovascular Stent Grafts, Occluders, and Femoral-Femoral Artery Bypass

While competing in an obstacle course race, a 57-year-old male athlete developed left groin and leg pain. Several days later, infrarenal aortic dissection with clinically worsening left leg ischemia was diagnosed. An emergent repair was performed and consisted of an aorto-uni-iliac endovascular stent graft, an occluder in the left iliac artery, and a right-to-left femoral-femoral artery bypass. To the authors' knowledge, the present report is the first case of a spontaneous infrarenal aortic dissection in a competitive athlete associated with participation in an extreme athletic event.

Local variations in material and structural properties characterize murine thoracic aortic aneurysm mechanics

We recently developed an approach to characterize local nonlinear, anisotropic mechanical properties of murine arteries by combining biaxial extension-distension testing, panoramic digital image correlation, and an inverse method based on the principle of virtual power. This experimental-computational approach was illustrated for the normal murine abdominal aorta assuming uniform wall thickness. Here, however, we extend our prior approach by adding an optical coherence tomography (OCT) imaging system that permits local reconstructions of wall thickness. This multimodality approach is then used to characterize spatial variations of material and structural properties in ascending thoracic aortic aneurysms (aTAA) from two genetically modified mouse models (fibrillin-1 and fibulin-4 deficient) and to compare them with those from angiotensin II-infused apolipoprotein E-deficient and wild-type control ascending aortas. Local values of stored elastic energy and biaxial material stiffness, computed from spatial distributions of the best fit material parameters, varied significantly with circumferential position (inner vs. outer curvature, ventral vs. dorsal sides) across genotypes and treatments. Importantly, these data reveal an inverse relationship between material stiffness and wall thickness that underlies a general linear relationship between stiffness and wall stress across aTAAs. OCT images also revealed sites of advanced medial degeneration, which were captured by the inverse material characterization. Quantification of histological data further provided high-resolution local correlations among multiple mechanical metrics and wall microstructure. This is the first time that such structural defects and local properties have been characterized mechanically, which can better inform computational models of aortopathy that seek to predict where dissection or rupture may initiate.

Cerebral blood flow, frontal lobe oxygenation and intra-arterial blood pressure during sprint exercise in normoxia and severe acute hypoxia in humans

Cerebral blood flow (CBF) is regulated to secure brain O₂ delivery while simultaneously avoiding hyperperfusion; however, both requisites may conflict during sprint exercise. To determine whether brain O₂ delivery or CBF is prioritized, young men performed sprint exercise in normoxia and hypoxia (P_IO₂ = 73 mmHg). During the sprints, cardiac output increased to ∼22 L min^-1, mean arterial pressure to ∼131 mmHg and peak systolic blood pressure ranged between 200 and 304 mmHg. Middle-cerebral artery velocity (MCAv) increased to peak values (∼16%) after 7.5 s and decreased to pre-exercise values towards the end of the sprint. When the sprints in normoxia were preceded by a reduced P_ETCO₂, CBF and frontal lobe oxygenation decreased in parallel ( r = 0.93, P < 0.01). In hypoxia, MCAv was increased by 25%, due to a 26% greater vascular conductance, despite 4-6 mmHg lower PaCO₂ in hypoxia than normoxia. This vasodilation fully accounted for the 22 % lower CaO₂ in hypoxia, leading to a similar brain O₂ delivery during the sprints regardless of P_IO₂. In conclusion, when a conflict exists between preserving brain O₂ delivery or restraining CBF to avoid potential damage by an elevated perfusion pressure, the priority is given to brain O₂ delivery.

Interrepetition Rest Set Lacks the V-Shape Systolic Pressure Response Advantage during Resistance Exercise

Resistance exercise may lead to an aneurysm due to dangerous levels of systemic hypertension. Thus, a minimized pressure response during exercise may guarantee safer training. For that, we analyzed an interrepetition rest design (IRD) hypothesizing that it would produce a lower systolic blood pressure (SBP) response in comparison with a continuous design (CD). Additionally, we studied the effect of accumulated repetitions on the increasing SBP rate during the first continuous set. Fifteen healthy participants (age: 24 ± 2 years; SBP: 113 ± 8 mmHg) performed leg presses, with 40 repetitions and 720 s of total rest, structured in an IRD of individual repetitions (resting time: 18.5 s), and in a CD of five sets of eight repetitions (resting time: 180 s). Analyses reported an increase (p = 0.013) in the mean peaks of SBP in the IRD (162 ± 21 mmHg), versus the CD (148 ± 19 mmHg), while both augmented versus baselines (p < 0.001). Additionally, the linear model estimated a progressive increase of SBP of around 7 mmHg per repetition. Summarily, the IRD produced a higher mean of the SBP peaks during the 40 repetitions due to lacking the v-shape advantage in comparison with the CD.

Genetic diagnostics of inherited aortic diseases : Medical strategy analysis

Genetic aortic syndromes (GAS) include Marfan, Loeys-Dietz, vascular Ehlers-Danlos, and Turner syndrome as well as congenital bicuspid aortic valve. The clinical management of these diseases has certain similarities and differences. We employed medical strategy analysis to test the utility of genetic diagnostics in the management of GAS. We chose the standpoint of the cardiologist for our analysis. In the first step, the medical goals in the management of GAS are specified. In the second step, the accuracy of genetic diagnostics for GAS is examined. Finally, conclusions can be drawn about the utility of genetic diagnostics in managing GAS. We found that genetic diagnostics is necessary to exclude GAS, to diagnose GAS, and to specify disease types. Second, combining phenotype with genotype information maximizes the predictability of the course of disease. Third, with genetic diagnostics it is possible to predict the birth of children with causative mutations for GAS and to initiate drug therapy to prevent the onset of aortic dilatation or to slow down its progression to aortic aneurysm. Finally, genetic diagnostics improves prognostic predictions and thereby contributes to a better timing of elective surgery and to a better choice of procedures. The findings of our medical strategy analysis indicate the high utility of genetic diagnostics for managing GAS.

Altered Smooth Muscle Cell Force Generation as a Driver of Thoracic Aortic Aneurysms and Dissections

The importance of maintaining contractile function in aortic smooth muscle cells (SMCs) is evident by the fact that heterozygous mutations in the major structural proteins or kinases controlling contraction lead to the formation of aneurysms of the ascending thoracic aorta that predispose to life-threatening aortic dissections. Force generation by SMC requires ATP-dependent cyclic interactions between filaments composed of SMC-specific isoforms of α-actin (encoded by ACTA2) and myosin heavy chain (MYH11). ACTA2 and MYH11 mutations are predicted or have been shown to disrupt this cyclic interaction predispose to thoracic aortic disease. Movement of the myosin motor domain is controlled by phosphorylation of the regulatory light chain on the myosin filament, and loss-of-function mutations in the dedicated kinase for this phosphorylation, myosin light chain kinase (MYLK) also predispose to thoracic aortic disease. Finally, a mutation in the cGMP-activated protein kinase (PRKG1) results in constitutive activation of the kinase in the absence of cGMP, thus driving SMC relaxation in part through increased dephosphorylation of the regulatory light chain and predisposes to thoracic aortic disease. Furthermore, SMCs cannot generate force without connections to the extracellular matrix through focal adhesions, and mutations in the major protein in the extracellular matrix, fibrillin-1, linking SMCs to the matrix also cause thoracic aortic disease in individuals with Marfan syndrome. Thus, disruption of the ability of the aortic SMC to generate force through the elastin-contractile units in response to pulsatile blood flow may be a primary driver for thoracic aortic aneurysms and dissections.