Time-dependent mechanical behaviour of the aortic chronic dissection flap.

OBJECTIVES: The transition of aortic dissection from acute to chronic is poorly understood. We examined time-dependent mechanical behaviour and biochemical properties of chronic dissection tissues. METHODS: Aorta samples were obtained from 14 patients with mixed aetiology who were undergoing elective surgery for chronic dissected aneurysms, ranging from 3 months to 15 years post-dissection. The tissue elastic modulus and tissue deformation following application of loading for 5 h were measured for the false lumen (FL), true lumen (TL) and flap (FP) tissues with a custom-indentation technique. Collagen, elastin and glycosaminoglycan levels were determined with established biochemical assays. Elastin fragmentation was graded from histological sections. The number of tissues characterized was as follows: FP (n = 10), TL (n = 5 for biomechanical testing, n = 8 for biochemical analysis, n = 8 for histological assessment) and FL (n = 4). RESULTS: Tissues stiffness was highest in FP [59.8 (14.8) kPa] as compared with TL [50.7 (6.2) kPa] and FL [40.5 (4.7) kPa] (P = 0.023 and P = 0.006, respectively). FP [0.5 (0.08) mm] also exhibited reduced deformation relative to TL [0.7 (0.02) mm] and FL [0.9 (0.08) mm] (P = 0.003 and P = 0.006, respectively), lowest collagen concentration [FP: 40.1 (19.6) µg/mg, TL: 59.9 (19.5) µg/mg, P = 0.008; FL: 79.1 (32.0) µg/mg, P = 0.006] and the lowest collagen: elastin ratio [0.4 (0.1)] relative to the other tissues [TL; 0.6 (0.3), P = 0.006, FL; 1.5 (0.4); P = 0.003]. Significant elastin loss was evident in the FL-stained tissue sections whereas highly aligned, long fibres were visible in the FP and TL. A linear relationship was found between the stiffness, deformation and the time from the dissection event to surgical intervention for the FP. All data are presented as median (interquartile range). CONCLUSIONS: FP exhibited reduced time-dependent deformation and distinct biochemical properties relative to TL and FL irrespective of connective tissue disorder or the anatomical region of the dissection.

Rapid evaporative ionization mass spectrometry (intelligent knife) for point-of-care testing in acute aortic dissection surgery.

OBJECTIVES: Rapid evaporative ionization mass spectrometry (REIMS) can discriminate aneurysmal from normal aortic tissue. Our objective in this work was to probe the integrity of acute dissection tissue using biomechanical, biochemical and histological techniques and demonstrate that REIMS can be used to discriminate identified differences. METHODS: Human aortic tissue was obtained from patients undergoing surgery for acute aortic dissection. Biomechanical, biochemical and histological assessment was carried out to probe mechanical properties and elastin, collagen and glycosaminoglycan composition of the tissue. Monopolar electrocautery was applied to samples and surgical aerosol aspirated and analysed by REIMS to produce mass spectral data. RESULTS: Tissue was obtained from 10 patients giving rise to 26 tissue pieces: 10 false lumen (FL), 10 dissection flap and 6 true lumen samples. Models generated from biomechanical and biochemical data showed that FL tissue was distinct from true lumen and dissection flap tissue. REIMS identified the same pattern being able to classify tissue types with 72.4% accuracy and 69.3% precision. Further analysis of REIMS data for FL tissue suggested patients formed 3 distinct clusters. Histological and biochemical assessment revealed patterns of extracellular matrix degradation within the clusters that are associated with altered tissue integrity identified using biomechanical testing. CONCLUSIONS: Structural integrity of the FL in acute Type A dissection could dictate future clinical distal disease progression. REIMS can detect differences in tissue integrity, supporting its development as a point-of-care test to guide surgical intraoperative decision-making.

Exploring the potential of rapid evaporative ionization mass spectrometry (Intelligent Knife) for point-of-care testing in aortic surgery.

OBJECTIVES: Many intraoperative decisions regarding the extent of thoracic aortic surgery are subjective and are based on the appearance of the aorta, perceived surgical risks and likelihood of early recurrent disease. Our objective in this work was to carry out a cross-sectional study to demonstrate that rapid evaporative ionization mass spectrometry (REIMS) of electrosurgical aerosol is able to empirically discriminate ex vivo aneurysmal human thoracic aorta from normal aorta, thus providing supportive evidence for the development of the technique as a point-of-care test guiding intraoperative surgical decision-making. METHODS: Human aortic tissue was obtained from patients undergoing surgery for thoracic aortic aneurysms (n = 44). Normal aorta was obtained from a mixture of post-mortem and punch biopsies from patients undergoing coronary surgery (n = 13). Monopolar electrocautery was applied to samples and surgical aerosol aspirated and analysed by REIMS to produce mass spectral data. RESULTS: Models generated from REIMS data can discriminate aneurysmal from normal aorta with accuracy and precision of 88.7% and 85.1%, respectively. In addition, further analysis investigating aneurysmal tissue from patients with bicuspid and tricuspid aortic valves was discriminated from normal tissue and each other with accuracies and precision of 93.5% and 91.4% for control, 83.8% and 76.7% for bicuspid aortic valve and 89.3% and 86.0% for tricuspid aortic valve, respectively. CONCLUSIONS: Analysis of electrosurgical aerosol from ex vivo aortic tissue using REIMS allowed us to discriminate aneurysmal from normal aorta, supporting its development as a point-of-care test (Intelligent Knife) for guiding surgical intraoperative decision-making.

Outcomes of acute type A aortic dissection repair: Daytime versus nighttime.

Objective: We sought to report our experience of repairing acute type A aortic dissection (ATAAD) over 21 years during in-hours versus out-of-hours before and after the establishment of specialized aortic service and rota. Methods: A retrospective analysis of all patients who had ATAAD repair between November 1998 and December 2019 in our center. In-hours were defined as 08:00 to 19:59 hours and out of hours were defined as 20:00 to 07:59 hours. Results: A total of 286 patients underwent repair of ATAAD. Eighty operations took place during the prerota period (43 operations in hours, 37 out of hours) and 206 operations during the specialized rota period (110 in hours, 96 out of hours). There was no difference in 30-day mortality between the in-hours and out-of-hours groups in either the prerota (23.3% vs 32.4%; P = .36) or specialized rota periods (11.6% vs 11.5%; P = .94). Mean number of cases per year increased by 83% between the prerota and specialized rota periods. Thirty-day mortality reduced in both the in-hours (23.3% vs 11.6%) and out-of-hours (32.4% vs 11.5%) groups since introduction of the specialized aortic rota. Conclusions: Outcomes in repair of ATAAD during in-hours and out-of-hours periods are similar when operated on in a specialized unit with a dedicated aortic team. This emphasizes the current global trend of service centralization without particular attention to time of day to operate on such critical cohort patients.

Systematic approach to diagnosis and management of infected prosthetic grafts in the proximal aorta.

OBJECTIVES: Management of infected prosthetic aortic grafts in the ascending and or root is complex and multifaceted. We report our diagnostic pathway, management and outcomes, identifying successful strategies. METHODS: This was a retrospective, single center, observational study. Consecutive patients who underwent management of infected aortic grafts in the ascending and/or root at our institution between October 1998 and December 2019 were included. The main outcome measures were: discharge from hospital alive with at least 1 year survival, operative mortality and success of primary treatment strategy. RESULTS: Twenty-six patients presented with infection of proximal aortic grafts and were managed through a number of strategies with an overall hospital-survival of 81% and 1 year survival of 69%. Twenty of them ultimately underwent redo surgery with 25% operative mortality (within 24 h of surgery). Five patients underwent washout and irrigation of which two were successfully treated and cured with adjunctive antibiotics and two went on to have staged explant and definitive surgery. Interval between surgery and infection was 42.5 ± 35.8 months. All patients had at least one major criterion and three minor criterions with no diagnostic uncertainty. The commonest primary strategy was 3a (definitive surgery), (13/26, 50%). CONCLUSIONS: Adopting a systematic and flexible patient specific approach to the diagnosis and management of patients with proximal aortic graft infections results in reasonable overall 1 year survival. In the majority of patients surgery is ultimately required in an attempt to achieve a curative treatment; however this comes with high operative mortality risk.

Reinterventions and new aortic events after aortic surgery in Marfan syndrome.

OBJECTIVES: Pre-emptive strategies to manage the aortic complications of Marfan syndrome have resulted in improved life expectancy yet, secondary to the variation of phenotypic expression, anticipating the risk and nature of future aortic events is challenging. We examine rates of new aortic events and reinterventions in a Marfan cohort following initial aortic presentation. METHODS: Retrospective cohort study of Marfan patients with aortic pathology presenting to our institution 1998-2018. Patients were grouped according to index event: aortic dissection or root aneurysm. Patients with aortic dissection were classified according to Debakey criteria. Incidence of new aortic events and frequency of reintervention were analysed. RESULTS: One hundred and twenty-six aortic procedures were performed in 74 Marfan patients with a median follow-up of 7 years. Forty-seven patients had an index event of root aneurysm and 27 had aortic dissection. Following operative intervention in the aneurysm group, 7 patients developed Debakey III dissections raising the overall number of patients who developed dissection within this cohort to 34. Reinterventions were more frequent in the dissection group with full replacement of the native aorta in 5 patients. CONCLUSIONS: After operative intervention on the proximal aorta, a proportion will develop distal pathology. A greater focus on factors contributing to future events, such as mapping genotypes to clinical course, may lead the way for targeted operative techniques and surveillance.

COVID-19 and cardiac surgery: A perspective from United Kingdom.

The emergence of severe acute respiratory syndrome coronavirus 2 in December 2019, presumed from the city of Wuhan, Hubei province in China, and the subsequent declaration of the disease as a pandemic by the World Health Organization as coronavirus disease 2019 (COVID-19) in March 2020, had a significant impact on health care systems globally. Each country responded to this disease in different ways, however this was done broadly by fortifying and prioritizing health care provision as well as introducing social lockdown aiming to contain the infection and minimizing the risk of transmission. In the United Kingdom, a lockdown was introduced by the government on March 23, 2020 and all health care services were focussed to challenge the impact of COVID-19. To do so, the United Kingdom National Health Service had to undergo widespread service reconfigurations and the so-called "Nightingale Hospitals" were created de novo to bolster bed provision, and industries were asked to direct efforts to the production of ventilators. A government-led public health campaign was publicized under the slogan of: "Stay home, Protect the NHS (National Health Service), Save lives." The approach had a significant impact on the delivery of all surgical services but particularly cardiac surgery with its inherent critical care bed capacity. This paper describes the impact on provision for elective and emergency cardiac surgery in the United Kingdom, with a focus on aortovascular disease. We describe our aortovascular activity and outcomes during the period of UK lockdown and present a patient survey of attitudes to aortic surgery during COVID-19 pandemic.

Contemporary results of open thoracic and thoracoabdominal aortic surgery in a single United Kingdom center.

OBJECTIVE: To report our outcomes and identify predictors of mortality after open descending thoracic aneurysm (DTA) and thoracoabdominal aortic aneurysm (TAAA) repair in a specialist aortic center. METHODS: This retrospective observational cohort study included consecutive patients who underwent surgery at our institution between October 1998 and December 2019. The main outcome measures were mortality and major morbidities. A multivariate analysis was used to identify predictors of mortality. RESULTS: There were 430 patients who underwent DTA (n = 157) and TAA (n = 273) repair; 151 underwent surgery nonelectively. Forty-eight patients (11%) died within 30 days of surgery. The 30-day mortality was lower after elective surgery (3.1% after DTA repair and 9.9% after TAAA repair), whereas nonelective surgery had a 30-day mortality of 17.9%. Fourteen additional patients died in hospital after 30 days, one after nonelective DTA repair and 13 after TAAA repair (10 elective), all but one extent II. In-hospital mortality for the whole cohort improved over time, as the activity volume increased, except for patients undergoing extent II TAAA repair. Predictors of in-hospital mortality were age ≥70 years (odds ratio [OR], 3.36; 95% confidence interval [CI], 1.79-6.32; P < .001), extent II repair (OR, 4.39; 95% CI, 2.34-8.21; P < .001), nonelective surgery (OR, 2.72; 95% CI, 1.44, 5.12; P = .002), out-of-hours surgery (OR, 8.17; 95% CI, 2.16-30.95; P = .002), a left ventricular ejection fraction of <30% (OR, 9.86; 95% CI, 1.91-50.86; P < .006), and surgery for a degenerative aneurysm (OR, 2.20; 95% CI, 1.12-4.31; P = .02). The incidence of stroke and paraplegia was 7.1% and 0% after DTA repair and 9.9% and 3.3% after TAAA repair. Hemodialysis was necessary in 5.1% of cases after DTA repair and 22.7% after TAAA repair. CONCLUSIONS: Open thoracoabdominal aortic surgery carries significant risk to life, which is related to age, extent of aortic replacement, timing of surgery, and left ventricular function. Morbidity is considerable. Understanding these risks is fundamental for patient selection and the consent process of potential candidates for surgery, particularly in the elderly.

Frozen elephant trunk does not increase incidence of paraplegia in patients with acute type A aortic dissection.

OBJECTIVE: We seek to assess the safety of total arch replacement with frozen elephant trunk for acute type A aortic dissection in respect to the risks of operative mortality, stroke, and paraplegia using an international multicenter registry (ARCH). METHODS: The ARCH Registry database from 37 participating centers was analyzed between 2000 and 2015. Patients who underwent emergency surgery for acute type A aortic dissection treated by total arch replacement with or without frozen elephant trunk were included. Operative mortality, permanent neurologic deficits, and spinal cord injury were primary end points. These end points were analyzed using univariate and hierarchical multivariate regression analyses, as well as conditional logistic regression analysis and post hoc propensity-score stratification. RESULTS: A total of 11,928 patients were enrolled in the ARCH database, of which 6180 were managed with total arch replacement. A comprehensive analysis was performed for 978 patients who underwent total aortic arch replacement for acute type A aortic dissection with or without frozen elephant trunk placement. In propensity-score matching, there were no significant differences between total arch replacement and frozen elephant trunk in terms of permanent neurologic deficits (11.9% vs 10.1%, P = .59) and spinal cord injury (4.0% vs 6.3%, P = .52) For patients included in the post hoc propensity-score stratification, frozen elephant trunk was associated with a statistically significantly lower mortality risk (odds ratio, 0.47; P = .03). CONCLUSIONS: The use of frozen elephant trunk for acute type A aortic dissection does not appear to increase the risk of paraplegia in appropriately selected patients at experienced centers. The exact risk factors for paraplegia remain to be determined.

Bicuspid valve aortopathy is associated with distinct patterns of matrix degradation.

OBJECTIVE: To explore the micromechanical, biochemical, and microstructural differences between bicuspid aortic valve aneurysm (BAV-A) and tricuspid aortic valve idiopathic degenerative aneurysm (DA), compared with normal aorta. METHODS: Aortic tissue was obtained from patients undergoing aneurysmal repair surgery (BAV-A; n = 15 and DA; n = 15). Control tissue was obtained from aortic punch biopsies during coronary artery bypass graft surgery (n = 9). Nanoindentation was used to determine the elastic modulus on the medial layer. Glycosaminoglycan, collagen, and elastin levels were measured using biochemical assays. Verhoeff Van Gieson-stained cross-sections were imaged for elastin microstructural quantification. RESULTS: The elastic modulus was more than 20% greater for BAV-A relative to control and DA (signifying a loss of compliance). No significance difference between control and DA were observed. Collagen levels for BAV-A (36.9 ± 7.4 µg/mg) and DA (49.9 ± 10.9 µg/mg) were greater compared with the control (30.2 ± 13.1 µg/mg). Glycosaminoglycan and elastin levels were not significant between the groups. Elastin segments were uniform throughout the control. Aneurysmal tissues had less elastin segments close to the intima and adventitia layers. Both BAV-A and DA had elastin segments compacted in the media; however, elastin segments were highly fragmented in DA. CONCLUSIONS: BAV-A has a greater loss of aortic wall compliance relative to DA and the control. Although elastin levels were equal for all groups, spatial distribution of elastin provided a unique profile of matrix degradation for BAV-A. Elastin compaction within the media of BAV-A may have resulted from the altered hemodynamic pressure against the wall, which could explain for the stiffness of the tissue.

Retrograde aortic access during ventricular tachycardia ablation: Indications, techniques, and challenges.

The retrograde aortic (RA) route is a widely used access route for mapping and ablation of ventricular tachycardias (VT) arising from the left ventricular endocardium. With the expanding role of VT ablation in patients with significant comorbidity, the choice between the RA and transseptal access routes is an increasingly important consideration. An individualized decision based on the location of the arrhythmogenic substrate, vascular anatomy, aortic valve morphology, and operator experience is necessary when deciding on the optimal access route. Among patients with challenging vascular anatomy, growing experience from structural interventions such as transcatheter aortic valve replacements and peripheral vascular interventions has provided valuable insights into techniques for safe retrograde access. The present review focuses on patient selection for RA access, potential complications associated with the technique, and optimal approaches for access in patients with challenging vascular or aortic valve anatomy.

Reducing Blood Transfusion in Aortic Surgery: A Novel Approach.

BACKGROUND: We introduced a new algorithm utilizing a patient's own platelet rich plasma and factor concentrates to better manage coagulopathy in aortic surgery under circulatory arrest. This study compares the outcomes of the patients treated with a new algorithm with those of patients managed with our traditional approach. METHODS: The data of 247 consecutive patients who had aortic surgery were analyzed. The 158 patients (group 1) who were managed with our usual algorithm were compared with the 89 patients (group 2) who were treated with the novel algorithm consisting of utilization of the patient's own platelet rich plasma, fibrinogen, and prothrombin cell concentrates. Differences in transfusion and intensive care unit stay were analyzed. Univariate and multivariable robust regression analyses were performed. RESULTS: In comparison with group 1, patients in group 2 had significantly reduced need for transfusion of red cells (7.9 ± 8.6 vs 3.5 ± 3.8 units, P < .001). Postoperative intubation time was reduced from a mean of 42 hours to a mean of 12 hours (P < .001). The time to medical discharge from the intensive care unit was reduced from a mean of 7 days to a mean of 5 days (P < .001), favoring the new algorithm. After adjustment for demographics and comorbidities, the novel algorithm remained significantly associated with a reduction in units of red blood cells transfused (robust parameter estimate, -1.14; P = .027) and blood products transfused (robust parameter estimate, -5.11; P < .001). CONCLUSIONS: Using autologous plasma and factor concentrates to reverse coagulopathy in aortic surgery significantly reduces blood product transfusion.

Idiopathic degenerative thoracic aneurysms are associated with increased aortic medial amyloid.

Objective: To explore the relationship of aortic medial amyloid with biochemical and micromechanical properties of the aortic wall in aneurysm patients. Methods: Human aortic tissues removed during aneurysm surgery from tricuspid (idiopathic degenerative aneurysm, DA) and bicuspid valve (BAV) patients were subjected to oscillatory nanoindentation experiments to determine localised mechanical properties of the tissue (shear storage modulus, G´ and shear loss modulus, G˝). Collagen, elastin, matrix metalloproteinase 2 and glycosaminoglycans concentrations were determined, along with relative levels of aortic medial amyloid-related factors (medin, milk fat globule-EGF factor 8, oligomers and fibrils). Measurements were combined with clinical data and statistical analyses performed. Results: The DA cohort can be divided based on their phenotype. One group shared similar characteristics with BAV patients, termed bicuspid like phenotype-tricuspid valve. The second group had high amyloid oligomer species present with a significantly lower G´ (p = .01), indicative of reduced elastic response of the tissue, termed amyloid-rich. Conclusions: We identified a group of DA patients with high amyloid oligomers and altered micromechanical and structural properties of the vessel wall. We propose these findings as a cause for aneurysm formation in these patients. Amyloid is not found in BAV patients, suggesting at least two distinct mechanisms for pathogenesis.

Sternal Wires-Induced Severe Systemic Inflammatory Response and Cardiac Tamponade.

Nickel hypersensitivity has been reported in up to 15% of the general population, and cases of nickel allergy have been correlated with use of stainless steel wires. This is a case report of a 48-year-old woman with history of contact allergy to metal who underwent elective coronary artery bypass grafting. Severe systemic inflammatory response and cardiac tamponade due to edema of mediastinal tissues developed postoperatively. The patient required removal of stainless steel wires and delayed sternal closure with Ethibond (Ethicon, Somerville, NJ) sutures in addition to intravenous steroids. In patients with hypersensitivity to nickel, other alternatives closure methods should be considered.

Bioprosthetic mitral valve thrombosis and subsequent obstruction from non-Hodgkins lymphoma despite anticoagulation.

Malignancy can cause a hypercoagulable state, it rarely causes prosthetic valve thrombosis, with only limited cases reports due to lymphoma. Although no standardised approach for treatment exists, the combination of early diagnosis, surgical intervention and adjuvant chemotherapy are likely to provide the best chances of survival. We describe an interesting case of a bioprosthetic mitral valve thrombosis leading to valve obstruction in a patient with non-Hodgkin's lymphoma despite being on anticoagulation.

Deep circumferential annuloplasty as an adjunct to repair regurgitant bicuspid aortic valves with a dilated annulus.

BACKGROUND: Failure to address the functional aortic annulus during bicuspid aortic valve (BAV) repair has led to early repair failures. The pathology of regurgitant BAV involves annular dilatation, which is more pronounced anteriorly and deep toward the muscular interventricular septum. In this study, we assessed the results of BAV repair using a strategy of deep circumferential annular support involving the septum in patients with a dilated annulus (>26 mm) and moderate to severe aortic regurgitation (AR). METHODS: Between February 1999 and June 2015, 100 patients with regurgitant (≥2+) BAV and a dilated ventriculoaortic junction (VAJ) (≥26 mm) underwent repair with an adjunctive circumferential annuloplasty (reimplantation procedure or ring). External root dissection to accommodate the annuloplasty was carried deep onto the anterior aspect of the interventricular septum. Follow up was complete in 96 patients, with a median follow-up of 31 months and a total of 362 patient-years. Cox regression analysis was used to predict recurrence of AR. RESULTS: The mean VAJ diameter was 30 ± 4 mm. Seventy-nine patients exhibited delayed prolapse of the anterior leaflet (conjoined right and left cusps in Siever type 1 or anterior cusp in Siever type 0), and 93 patients underwent reimplantation. In the entire study group, there were no in-hospital deaths, and only 1 patient had 2+ AR on discharge. There was 1 late noncardiac death. At 8 years, freedom from AR ≥2+ was 96.4% and freedom from reoperation was 96.8%. Higher preoperative AR grade, small graft size, and use of a ring were predictive of recurrent AR. CONCLUSIONS: Regurgitant BAVs with a dilated annulus display anterior cusp prolapse toward the septum. A deep circumferential annuloplasty may help maintain repair durability.

Staged Repair of Concomitant Aortic Regurgitation and Descending Thoracic Aortic Aneurysm.

Descending thoracic aortic (DTA) aneurysms causing left main bronchus compression can be surgically repaired under left heart bypass (LHB). Safe LHB requires a competent aortic valve. Some patients present with concomitant DTA aneurysms and severe aortic regurgitation (AR), precluding LHB as an adjunct for aortic surgery. The authors present such a case and outline the management. AR can safely be addressed first in an immediate staged surgical approach, providing adequate left ventricular function.

Giant Aortic Thrombus in the Ascending Aorta and Perforation of Bowel Associated With Cocaine Use.

A floating giant aortic thrombus is a rare finding in the absence of any coagulation disorder. Patients usually remain asymptomatic until the development of embolic complications. Our report highlights cocaine abuse as a potential cause of aortic thrombus and bowel perforation. Clinicians should have a high index of suspicion when treating patients with a history of illicit cocaine use with signs and symptoms of arterial ischemia. The risks of cardiovascular and abdominal complications related to cocaine use should not be underestimated. Prompt diagnosis is required to circumvent potentially life-threatening complications.

Late aortic aneurysm after supravalvar aortic stenosis repaired with autologous pericardial patch.

We present a patient with a late aortic root aneurysm subsequent to an autologous pericardial patch repair of congenital supravalvar aortic stenosis (SVAS) performed 20 years earlier. There have been no reports of this complication to date, to our knowledge, and the mechanism of aneurysm formation after use of autologous pericardium is not well known. We presume that nonglutaraldehyde fixation and residual distal aortic arch stenosis contributed to aneurysm formation. We highlight the importance of correct selection of patch material, especially when used in the systemic circulation, if durable long-term outcomes are to be achieved.