Age is superior to aortopathy phenotype as a predictor of aortic mechanics in patients with bicuspid valve.

OBJECTIVES: Bicuspid aortic valve (BAV) aortopathy is defined by 3 phenotypes-root, ascending, and diffuse-based on region of maximal aortic dilation. We sought to determine the association between aortic mechanical behavior and aortopathy phenotype versus other clinical variables. METHODS: From August 1, 2016, to March 1, 2023, 375 aortic specimens were collected from 105 patients undergoing elective ascending aortic aneurysm repair for BAV aortopathy. Planar biaxial data (191 specimens) informed constitutive descriptors of the arterial wall that were combined with in vivo geometry and hemodynamics to predict stiffness, stress, and energy density under physiologic loads. Uniaxial testing (184 specimens) evaluated failure stretch and failure Cauchy stress. Boosting regression was implemented to model the association between clinical variables and mechanical metrics. RESULTS: There were no significant differences in mechanical metrics between the root phenotype (N = 33, 31%) and ascending/diffuse phenotypes (N = 72, 69%). Biaxial testing demonstrated older age was associated with increased circumferential stiffness, decreased stress, and decreased energy density. On uniaxial testing, longitudinally versus circumferentially oriented specimens failed at significantly lower Cauchy stress (50th [15th, 85th percentiles]: 1.0 [0.7, 1.6] MPa vs 1.9 [1.3, 3.1] MPa; P < .001). Age was associated with decreased failure stretch and stress. Elongated ascending aortas were also associated with decreased failure stress. CONCLUSIONS: Aortic mechanical function under physiologic and failure conditions in BAV aortopathy is robustly associated with age and poorly associated with aortopathy phenotype. Data suggesting that the root phenotype of BAV aortopathy portends worse outcomes are unlikely to be related to aberrant, phenotype-specific tissue mechanics.

Longitudinal versus circumferential biomechanical behavior of the aneurysmal ascending aorta.

OBJECTIVES: We evaluate the independent effects of patient and aortic tissue characteristics on biaxial physiologic mechanical metrics in aneurysmal and nonaneurysmal tissues, and uniaxial failure metrics in aneurysmal tissue, comparing longitudinal and circumferential behavior. METHODS: From February 2017 to October 2022, 382 aortic specimens were collected from 134 patients; 268 specimens underwent biaxial testing, and 114 specimens underwent uniaxial testing. Biaxial testing evaluated Green-Lagrange transition strain and low and high tangent moduli. Uniaxial testing evaluated failure stretch, Cauchy stress, and low and high tangent moduli. Longitudinal gradient boosting models were implemented to estimate mechanical metrics and covariates of importance. RESULTS: On biaxial testing, nonaneurysmal tissue was less deformable and exhibited a lower transition strain than aneurysmal tissue in the longitudinal (0.18 vs 0.30, P < .001) and circumferential (0.25 vs 0.30, P = .01) directions. Older age and increasing ascending aortic length contributed most to predicting transition strain. On uniaxial testing, longitudinal specimens failed at lower stretch (1.4 vs 1.5, P = .003) and Cauchy stress (1.0 vs 1.9 kPa, P < .001) than circumferential specimens. Failure stretch and Cauchy stress were most strongly associated with tissue orientation and decreased sharply with older age. Age, ascending aortic length, and tissue thickness were the most frequent covariates predicting mechanical metrics across 10 prediction models. CONCLUSIONS: Age was the strongest predictor of mechanical behavior. After adjusting for age, nonaneurysmal tissue was less deformable than aneurysmal tissue. Differences in longitudinal and circumferential mechanics contribute to tissue dysfunction and failure in ascending aneurysms. This highlights the need to better understand the effects of age, ascending aortic length, and thickness on clinical aortic behavior.

The modified frozen elephant trunk may outperform limited and extended-classic repair in acute type I dissection.

OBJECTIVES: A better surgical approach for acute DeBakey type I dissection has been sought for decades. We compare operative trends, complications, reinterventions and survival after limited versus extended-classic versus modified frozen elephant trunk (mFET) repair for this condition. METHODS: From 1 January 1978 to 1 January 2018, 879 patients underwent surgery for acute DeBakey type I dissection at Cleveland Clinic. Repairs were limited to the ascending aorta/hemiarch (701.79%) or extended through the arch [extended classic (88.10%) or mFET (90.10%)]. Weighted propensity score matched established comparable groups. RESULTS: Among weighted propensity-matched patients, mFET repair had similar circulatory arrest times and postoperative complications to limited repair, except for postoperative renal failure, which was twice as high in the limited group [25% (n = 19) vs 12% (n = 9), P = 0.006]. Lower in-hospital mortality was observed following limited compared to extended-classic repair [9.1% (n = 7) vs 19% (n = 16), P = 0.03], but not after mFET repair [12% (n = 9) vs 9.5% (n = 8), P = 0.6]. Extended-classic repair had higher risk of early death than limited repair (P = 0.0005) with no difference between limited and mFET repair groups (P = 0.9); 7-year survival following mFET repair was 89% compared to 65% after limited repair. Most reinterventions following limited or extended-classic repair underwent open reintervention. All reinterventions following mFET repair were completed endovascularly. CONCLUSIONS: Without increasing in-hospital mortality or complications, less renal failure and a trend towards improved intermediate survival, mFET may be superior to limited or extended-classic repair for acute DeBakey type I dissections. mFET repair facilitates endovascular reintervention, potentially reducing future invasive reoperations and warranting continued study.

Lengthwise regional mechanics of the human aneurysmal ascending thoracic aorta.

The prognosis of patients undergoing emergency endovascular repair of ascending thoracic aortic aneurysm (ATAA) depends on defect location, with root disease bearing worse outcomes than proximal or distal aortopathy. We speculate that a spatial gradient in aneurysmal tissue mechanics through the length of the ascending thoracic aorta may fuel noted survival discrepancies. To this end, we performed planar biaxial testing on 153 root, proximal, and distal segments of ATAA samples collected from 80 patients receiving elective open surgical repair. Following data averaging via surface fitting-based interpolation of strain-controlled protocols, we combined in-vitro and in-vivo measurements of loads and geometry to resolve inflation-extension kinematics and evaluate mechanical metrics of stress, stiffness, and energy at consistent deformation levels. Representative (averaged) experimental data and simulated in-vivo conditions revealed significantly larger biaxial stiffness at the root compared to either proximal or distal tissues, which persisted as the entire aorta stiffened during aging. Advancing age further reduced biaxial stretch and energy storage, a measure of aortic function, across all ATAA segments. Importantly, age emerged as a stronger predictor of tissue mechanics in ATAA disease than either bicuspid aortic valve or connective tissue disorders. Besides strengthening the general understanding of aneurysmal disease, our findings provide specifications to customize the design of stent-grafts for the treatment of ATAA disease. Optimization of deployment and interaction of novel endovascular devices with the local native environment is expected to carry significant potential for improving clinical outcomes. STATEMENT OF SIGNIFICANCE: Elucidating the lengthwise regional mechanics of ascending thoracic aortic aneurysms (ATAAs) is critical for the design of endovascular devices tailored to the ascending aorta. Stent-grafts provide a less invasive alternative to support the long-term survival of ATAA patients ineligible for open surgical repair. In this study, we developed a numerical framework that combines semi-inverse constitutive and forward modeling with in-vitro and in-vivo data to extract mechanical descriptors of ATAA tissue behavior at physiologically meaningful deformation. Moving distally from the aortic root to the first ascending aortic branch, we observed a progressive decline in biaxial stiffness. Furthermore, we showed that aging leads to reduced aortic function and is a stronger predictor of mechanics than either valve morphology or underlying syndromic disorder.

Ex vivo biaxial load testing analysis of aortic biomechanics demonstrates variation in elastic energy distribution across the aortic zone zero.

OBJECTIVES: We hypothesized that tissue characteristics vary significantly along zone zero, which may be reflected by regional differences in stored elastic energy. Our objectives were to (1) characterize the regional variation in stored elastic energy within tissues of the aortic zone zero and (2) identify the association between this variation and patient characteristics. METHODS: From February 2018 to January 2021, 123 aortic tissue samples were obtained from the aortic root and proximal and distal ascending aortas of 65 adults undergoing elective ascending aorta replacement. Biaxial biomechanics testing was performed to obtain tissue elastic energy at the inflection point and compared with patient demographics and preoperative computed tomography imaging. Coefficient models were fit using B-spline to interrogate the relationship among elastic energy, region, and patient characteristics. RESULTS: Mean elastic energy at inflection point was 24.3 ± 15.6 kJ/m3. Elastic energy increased significantly between the root and proximal, and root and distal ascending aorta and decreased with increasing age. Differences due to history of connective tissue disorder and bicuspid aortic valve were significant but diminished when controlled for other patient characteristics. Among covariates, age and region were found to be the most important predictors for elastic energy. CONCLUSIONS: Aortic tissue biomechanical metrics varied across regions and with patient characteristics within the aortic zone zero. Assessment of endovascular outcomes in the ascending aorta must closely consider the region of deployment and variable tissue qualities along the length of the landing zone. Regional variation in tissue characteristics should be incorporated into existing patient-specific models of aortic mechanics.

Ascending aorta mechanics and dimensions in aortopathy - from science to application.

The ascending aorta has a unique microstructure and biomechanical properties that allow it to absorb energy during systole and return energy during diastole (Windkessel effect). Derangements in aortic architecture can result in changes to biomechanics and inefficiencies in function. Ultimately biomechanical failure may occur resulting in aortic dissection or rupture. By measuring aortic biomechanics with either in vivo or ex vivo methods, one may be able to predict tissue failure in patients with aortic disease such as aneurysms. An understanding of the biomechanical changes that lead to these tissue-level failures may help guide therapy, disease surveillance, surgical intervention, and aid in the development of new treatments for this deadly condition.

Outcomes and role of peripheral revascularization in type A aortic dissection presenting with acute lower extremity ischemia.

OBJECTIVE: Limited data exists on management and outcomes of patients presenting with type A aortic dissection (TAAD) and acute lower extremity ischemia (ALI). The role of limb-related revascularization and optimal treatment strategy remains undefined. The objective of this study was to analyze dissection characteristics, treatment modalities, and outcomes of patients undergoing proximal aortic repair for TAAD with ALI. METHODS: Consecutive patients who underwent proximal aortic repair for TAAD were identified from a prospectively maintained database. Clinical data, imaging, operative details, and outcomes of patients with TAAD and ALI were retrospectively analyzed. Kaplan-Meier methodology was used to estimate overall and amputation-free survival. Log-rank tests were used to compare overall curves. Predictors of revascularization and in-hospital mortality were determined using multivariable logistic regression analysis. RESULTS: From 2010 to 2018, 463 patients with TAAD underwent proximal aortic repair. A total of 81 patients (17%) presented with ALI; 48% (39/81) with isolated ALI, and 52% (42/81) with ALI and renovisceral malperfusion. Thirty percent (24/81) required revascularization in addition to proximal aortic repair. Revascularization strategies involved endovascular (46%; 11/24), open (33%; 8/24), and hybrid (21%; 5/24) interventions. The major amputation rate was 4% (3/81), and in-hospital mortality was 21% (17/81). Amputation-free survival was significantly lower in patients requiring revascularization compared with those who did not (log-rank P = .023). Overall survival did not significantly differ between the two groups (log-rank P = .095). Overall survival was significantly lower in patients with concomitant ALI and renovisceral malperfusion compared with those with isolated ALI (log-rank P = .0017). Distal extent of dissection flap into zone 11 (odds ratio [OR], 5.65; 95% confidence interval [CI], 1.58-20.2; P = .008) and partial/complete thrombosis of any iliac artery (OR, 3.94; 95% CI, 1.23-12.6; P = .021) were associated with increased risk of requiring an additional revascularization procedure. True lumen collapse at level of renovisceral aorta (OR, 8.84; 95% CI, 1.74-44.9; P = .0086) was associated with increased risk of in-hospital mortality. CONCLUSIONS: ALI resolves after proximal aortic repair of TAAD in most cases. Distal extent of aortic dissection into zone 11 and iliac thrombosis are risk factors for additional peripheral revascularization. True lumen collapse at the renovisceral aorta and TAAD with concomitant ALI and renovisceral malperfusion portends a poor prognosis. A multi-disciplinary team approach to manage these patients who present with ascending aortic dissection and distal malperfusion may improve outcomes in this complex population.

Long-term Outcomes of Surgery for Invasive Valvular Endocarditis Involving the Aortomitral Fibrosa.

BACKGROUND: Reconstruction of the intervalvular fibrosa (IVF) for invasive double-valve infective endocarditis (IE) is a technically challenging operation. This study presents the long-term outcomes of two surgical techniques for IVF reconstruction. METHODS: From 1988 to 2017, 138 patients with invasive double-valve IE underwent surgical reconstruction of the IVF, along with double-valve replacement (Commando procedure, n = 86) or aortic valve replacement with mitral valve repair (hemi-Commando procedure, n = 52). Mean follow-up was 41 ± 5.9 months. RESULTS: Reoperation was required in 82% of patients, and 34% underwent emergency surgery. Pathologic features included positive blood cultures (90%), prosthetic valve IE (75%), aortic root abscess (78%), mitral annular abscess (24%), and intracardiac fistula (12%). There were 28 hospital deaths: 21 (24%) in the Commando group and 7 (14%) in the hemi-Commando group (P = .12). Overall survival at 1, 5, and 10 years was 67%, 48%, and 37%, respectively. Coronary artery disease, native valve IE, and causative organism (Staphylococcus aureus, coagulase-negative Staphylococcus, and viridans streptococci) were risk factors for late mortality. Freedom from reoperation at 1, 5, and 8 years was 87%, 74%, and 55%, respectively. Freedom from recurrent IE at 1, 5, and 8 years was 90%, 78%, and 67%, respectively. CONCLUSIONS: Although it is technically demanding, surgery for invasive IE involving IVF, which provides the only chance for cure, can be performed with reasonable clinical outcomes. In cases of IE invading the IVF and limited to the anterior mitral valve leaflet, a hemi-Commando procedure that includes mitral valve repair has improved early outcomes.

Cannulation strategies in acute type A dissection repair: A systematic axillary artery approach.

OBJECTIVES: Consensus regarding initial cannulation site for acute type A dissection repair is lacking. Objectives were to review our experience with systematic initial axillary artery cannulation, characterize patients on the basis of cannulation site, and assess outcomes. METHODS: From January 2000 to January 2017, 775 patients underwent emergency acute type A dissection repair. Initial axillary cannulation was performed in 617 (80%), femoral in 93 (12%), and central in 65 (8.4%). In-hospital mortality and stroke risk factors were identified using logistic regression. RESULTS: Reasons for selecting initial central or femoral instead of axillary cannulation included unsuitable axillary anatomy (n = 67; 42%), surgeon preference (n = 38; 24%), hemodynamic instability (n = 34; 22%), and preexisting cannulation (n = 19; 12%). Cannulation site was shifted or added intraoperatively in 82 (11%), with initial cannulation site being axillary (n = 23 of 617; 3.7%), central (6 of 65; 9.2%), or femoral (n = 53 of 93; 57%), for surgeon preference (n = 60; 73%), high flow resistance (n = 13; 16%), increased aortic false lumen flow (n = 6; 7.3%), and other (n = 3; 3.7%). In-hospital mortality was 8.6% (n = 67; lowest for axillary, 7.3% [P = .02]) and stroke 8.3% (n = 64). Hemodynamic instability (odds ratio [OR], 7.6; 95% confidence interval [CI], 4.2-14), limb ischemia (OR, 3.7; 95% CI, 1.5-9.3), stroke (OR, 5.5; 95% CI, 2.2-14), and aortic regurgitation (OR, 2.2; 95% CI, 1.2-4.2) at presentation were risk factors for mortality and central cannulation site (OR, 2.3; 95% CI, 1.05-5.1) and aortic stenosis (OR, 2.4; 95% CI, 1.2-4.6) for stroke. CONCLUSIONS: Systematic initial axillary cannulation for acute type A dissection repair is safe and effective and can be tailored to patients' specific needs. With this strategy, comparable outcomes are observed among cannulation sites and are largely determined according to patient presentation rather than cannulation site.

Advances in managing the noninfected open chest after cardiac surgery: Negative-pressure wound therapy.

OBJECTIVE: The objective of this study was to compare safety and clinical effectiveness of negative-pressure wound therapy (NPWT) with traditional wound therapy for managing noninfected open chests with delayed sternal closure after cardiac surgery. METHODS: From January 2000 to July 2015, 452 of 47,325 patients who underwent full sternotomy left the operating room with a noninfected open chest (0.96%), managed using NPWT in 214-with frequency of use rapidly increasing to near 100%-and traditionally in 238. Predominant indications for open-chest management were uncontrolled coagulopathy or hemodynamic compromise on attempted chest closure. Weighted propensity-score matching was used to assess in-hospital complications and time-related survival. RESULTS: NPWT and traditionally managed patients had similar high-risk preoperative profiles. Most underwent reoperations (63% of the NPWT group and 57% of the traditional group), and 21% versus 25% were emergency procedures. Reexplorations for bleeding were less common with NPWT versus traditional wound therapy (n = 63 [29%] vs 104 [44%], P = .002). Median duration of open-chest to definitive sternal closure was 3.5 days for NPWT versus 3.1 for traditionally managed patients (P[log rank] = .07). Seven patients (3.3%) were converted from NPWT to traditional therapy because of hemodynamic intolerance and 6 (2.5%) from traditional to NPWT. No NPWT-related cardiovascular injuries occurred. Among matched patients, NPWT was associated with better early survival (61% vs 44% at 6 months; P = .02). CONCLUSIONS: NPWT is safe and effective for managing noninfected open chests after cardiac surgery. By facilitating open-chest management and potentially improving outcomes, it has become our therapy of choice and perhaps has lowered our threshold for leaving the chest open after cardiac surgery.