Jehangir J. Appoo

Thoracic Aortic Frontier: Review of Current Applications and Directions of Thoracic Endovascular Aortic Repair (TEVAR)

Thoracic endovascular aortic repair, a minimally invasive technique is replacing the maximally invasive gold standard of thoracotomy and replacement of the descending thoracic aorta. With experience, indications have expanded to encroach on the arch and even ascending aorta. This review highlights the current state of technology, discusses controversies, and takes the perspective of a forward-thinking review to describe novel, innovative techniques that might make the entire thoracic aorta amenable to minimally invasive repair.

Mechano-biology in the thoracic aortic aneurysm: a review and case study

An aortic aneurysm is a permanent and localized dilatation of the aorta resulting from an irreversible loss of structural integrity of the aortic wall. The infrarenal segment of the abdominal aorta is the most common site of aneurysms; however, they are also common in the ascending and descending thoracic aorta. Many cases remain undetected because thoracic aortic aneurysms (TAAs) are usually asymptomatic until complications such as aortic dissection or rupture occurs. Clinical estimates of rupture potential and dissection risk, and thus interventional planning for TAAs, are currently based primarily on the maximum diameter and growth rate. The growth rate is calculated from maximum diameter measurements at two subsequent time points; however, this measure cannot reflect the complex changes of vessel wall morphology and local areas of weakening that underline the strong regional heterogeneity of TAA. Due to the high risks associated with both open and endovascular repair, an intervention is only justified if the risk for aortic rupture or dissection exceeds the interventional risks. Consequently, TAAs clinical management remains a challenge, and new methods are needed to better identify patients for elective repair. We reviewed the pathophysiology of TAAs and the role of mechanical stresses and mathematical growth models in TAA management; as a proof of concept, we applied a multiscale biomechanical analysis to a case study of TAA.

Canadian Cardiovascular Society/Canadian Society of Cardiac Surgeons/Canadian Society for Vascular Surgery Joint Position Statement on Open and Endovascular Surgery for Thoracic Aortic Disease

In 2014, the Canadian Cardiovascular Society (CCS) published a position statement on the management of thoracic aortic disease addressing size thresholds for surgery, imaging modalities, medical therapy, and genetics. It did not address issues related to surgical intervention. This joint Position Statement on behalf of the CCS, Canadian Society of Cardiac Surgeons, and the Canadian Society for Vascular Surgery provides recommendations about thoracic aortic disease interventions, including: aortic valve repair, perfusion strategies for arch repair, extended arch hybrid reconstruction for acute type A dissection, endovascular management of arch and descending aortic aneurysms, and type B dissection. The position statement is constructed using Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology, and has been approved by the primary panel, an international secondary panel, and the CCS Guidelines Committee. Advent of endovascular technology has improved aortic surgery safety and extended the indications of minimally invasive thoracic aortic surgery. The combination of safer open surgery with endovascular treatment has improved patient outcomes in this rapidly evolving subspecialty field of cardiovascular surgery.

Strategies in the surgical treatment of type A aortic arch dissection

Aortic dissection involving the ascending aorta is a lethal condition, with mortality approaching 60% if surgical intervention is not performed early (1). Stanford type A acute aortic dissection involves the ascending aorta, aortic arch and a variable extent of the descending thoracic aorta. Identification and resection of the primary intimal tear with re-approximation of the intima and adventitia remains the surgical principle of repair. Despite using this approach, a residual dissection flap persists in the arch and descending thoracic aorta in 64-90% of patients (2-5). This can lead to distal malperfusion in the acute setting (6), with a risk of aneurysm formation and rupture over the long term (7). Despite the advancement of cardiac surgery techniques, employment of modern cerebral protection strategies, myocardial protection, and aortic graft development, the surgical mortality of these operations, even in centers with a specific interest in aortic surgery, is in the range of 25% (8). In the modern era of cardiac surgery, it is rare to undertake a “common” operation with a mortality of 25% and this serves as a challenge for the cardiac surgery community to improve. In order to reduce this high operative mortality, one first needs to understand the contributing factors.

False positive computed tomographic angiography for Stanford type A aortic dissection

Background Computed tomographic angiography (CTA) has emerged as the defacto imaging test to rule out acute aortic dissection; however, it is not without flaws. We report a case of a false-positive CTA with respect to Stanford Type A aortic dissection. Case A 52 year-old male presented with sudden onset shortness of breath. He denied chest pain. Due to severe hypertension and an Emergency Department bedside ultrasound suggesting an intimal flap in the aorta, CTA was requested to better assess the ascending aorta and was interpreted as consistent with Stanford Type A aortic dissection with thrombosis of the false lumen in the ascending aorta. However, intra-operative imaging (TEE and epi-aortic scanning) did not identify an intimal flap or dissection, and neither did definitive surgical inspection of the aorta. The suspected aortic dissection and thrombosed false lumen were not visualized on repeat CTA two days later. Discussion False positive diagnosis of Stanford Type A aortic dissection on CTA can be the result of technical factors, streak artifacts, motion artifacts, and periaortic structures. In this case, non-uniform arterial contrast enhancement secondary to unrecognized biventricular dysfunction resulted in the false positive CTA appearance of an intimal flap and mural thrombus. Intra-operative TEE and epi-aortic scanning were proven correct in excluding aortic dissection by the standard of definitive surgical inspection of the aorta.

Acute aortic dissections with entry tear in the arch: a report from the International Registry of Acute Aortic Dissection (IRAD)

Objective: To analyze presentation, management, and outcomes of acute aortic dissections with proximal entry tear in the arch. Methods: Patients enrolled in the International Registry of Acute Aortic Dissection and entry tear in the arch were classified into 2 groups: arch A (retrograde extension into the ascending aorta with or without antegrade extension) and arch B (only antegrade extension into the descending aorta or further distally). Presentation, management, and in‐hospital outcomes of the 2 groups were compared. Results: The arch A (n = 228) and arch B (n = 140) groups were similar concerning the presence of any preoperative complication (68.4% vs 60.0%; P = .115), but the types of complication were different. Arch A presented more commonly with shock, neurologic complications, cardiac tamponade, and grade 3 or 4 aortic valve insufficiency and less frequently with refractory hypertension, visceral ischemia, extension of dissection, and aortic rupture. Management for both groups were open surgery (77.6% vs 18.6%; P < .001), endovascular treatment (3.5% vs 25.0%; P < .001), and medical management (16.2% vs 51.4%; P < .001). Overall in‐hospital mortality was similar (16.7% vs 19.3%; P = .574), but mortality tended to be lower in the arch A group after open surgery (15.3% vs 30.8%; P = .090), and higher after endovascular (25.0% vs 14.3%; P = .597) or medical treatment (24.3% vs 13.9%; P = .191), although the differences were not significant. Conclusions: Acute aortic dissection patients with primary entry tear in the arch are currently managed by a patient‐specific approach. In choosing the management type of these patients, it may be advisable to stratify them based on retrograde or only antegrade extension of the dissection. Graphical abstract Figure. No caption available.

Association of Mortality and Acute Aortic Events With Ascending Aortic Aneurysm: A Systematic Review and Meta-analysis

Key Points Question What are the growth rate and risk of complications in patients with moderately dilated ascending aortas? Findings This systematic review and meta-analysis of 20 studies including 8800 patients found that the ascending aorta growth rate was 0.61 mm/y, and the incidence of elective aortic surgery was 13.82%. The linearized mortality rate was 1.99% per patient-year, while the rate of aortic dissection, aortic rupture, and mortality was 2.16% per patient-year. Meaning More robust natural history data from prospective studies are needed to better inform clinical decision making in patients with ascending aortic aneurysms.

Cause of Death Following Surgery for Acute Type a Dissection: Evidence from the Canadian Thoracic Aortic Collaborative

BACKGROUND Surgery confers the best chance of survival following acute Type A dissection (ATAD), yet perioperative mortality remains high. Although perioperative risk factors for mortality have been described, information on the actual causes of death is sparse. In this study, we aimed to characterize the inciting events causing death during surgical repair of ATAD. METHODS Nine centers participated in the study. We included all patients who died following surgical repair for ATAD between January 2007 and December 2013. An aortic surgeon at each site determined the primary cause of death from seven predetermined categories: cardiac, stroke, hemorrhage, other organ ischemia (peripheral, renal, or visceral), multiorgan failure, sepsis, or other causes. Additional characteristics and variables were analyzed to delineate potential modifiable factors for mortality. RESULTS Of the 692 surgeries for ATAD, there were 123 deaths (17.8% mortality rate). Mean age at death was 66 years. Events contributing to death were: cardiac (25%), stroke (22%), hemorrhage (21%), multiorgan failure (12%), other organ ischemia (11%), sepsis (4%), and other causes (5%). Neurologic injury at presentation was a predictor of stroke as the inciting cause of death (p = 0.04). Peripheral, renal, or visceral ischemia at presentation was highly predictive of death due to these presenting ischemic conditions (p = 0.004). We found no associations between cardiogenic shock, tamponade, or cardiopulmonary bypass duration and cardiac death. CONCLUSION Operative mortality for ATAD remains high in Canada. Nearly 70% of deaths arise from cardiac failure, stroke, or hemorrhage. Therefore, novel surgical, hybrid, and endovascular strategies should target these three areas.BACKGROUND Surgery confers the best chance of survival following acute Type A dissection (ATAD), yet perioperative mortality remains high. Although perioperative risk factors for mortality have been described, information on the actual causes of death is sparse. In this study, we aimed to characterize the inciting events causing death during surgical repair of ATAD. METHODS Nine centers participated in the study. We included all patients who died following surgical repair for ATAD between January 2007 and December 2013. An aortic surgeon at each site determined the primary cause of death from seven predetermined categories: cardiac, stroke, hemorrhage, other organ ischemia (peripheral, renal, or visceral), multiorgan failure, sepsis, or other causes. Additional characteristics and variables were analyzed to delineate potential modifiable factors for mortality. RESULTS Of the 692 surgeries for ATAD, there were 123 deaths (17.8% mortality rate). Mean age at death was 66 years. Events contributing to death were: cardiac (25%), stroke (22%), hemorrhage (21%), multiorgan failure (12%), other organ ischemia (11%), sepsis (4%), and other causes (5%). Neurologic injury at presentation was a predictor of stroke as the inciting cause of death (p = 0.04). Peripheral, renal, or visceral ischemia at presentation was highly predictive of death due to these presenting ischemic conditions (p = 0.004). We found no associations between cardiogenic shock, tamponade, or cardiopulmonary bypass duration and cardiac death. CONCLUSION Operative mortality for ATAD remains high in Canada. Nearly 70% of deaths arise from cardiac failure, stroke, or hemorrhage. Therefore, novel surgical, hybrid, and endovascular strategies should target these three areas.

Infrarenal to Innominate Artery Collateral Complicating a Chronic Residual Type B Dissection

Residual type B aortic dissection following open surgical repair of a type A thoracic aortic dissection can sometimes be complicated by collateral blood supplies, which can impact existing flow patterns and result in progressive aneurysmal dilatation of the thoracic false lumens. We report a unique case that describes the clinical presentation of an infrarenal to innominate artery collateral blood flow that complicated a chronic residual type B dissection, which was diagnosed in a timely manner using multimodality imaging, and successfully managed through an innovative minimally invasive endovascular treatment strategy (without thoracotomy) with no neurological sequela.

Zone 2 Arch Replacement and Staged Thoracic Endovascular Aortic Repair for Acute Type A Aortic Dissection

Potential benefits of extending the distal extent of repair for acute type A aortic dissection beyond hemiarch has prompted the exploration of various total arch repair approaches. A zone 2 arch is advocated by some surgeons but the nomenclature and technique have not been described.