Aortic dissection and aortic aneurysm surgery: clinical observations, experimental investigations, and statistical analyses. Part II

The distribution of the depth of aortic dissection and the correlation of the dissection depth index with other parameters

BACKGROUND

In patients with aortic dissection, the aortic wall is separated into two layers along a dissection plane. In this study, a survey was performed to investigate the distribution of the depth of dissection plane and its correlation with other clinical and pathological parameters to help understand and expand the current knowledge of aortic dissection.

METHODS

Pathology information system were searched for patients with aortic dissection who had undergone aortic replacement between 2019 and 2022 in Wuhan Asia General Hospital. The depth of dissection plane and dissection depth index were measured in the area around the edge of dissection plane. Correlation between parameters was calculated using Spearman's rank correlation coefficient.

RESULTS

124 patients were included in this study. The depth of dissection plane ranged from 533 to 2335 microns, and the 5th percentile was 778 microns. The dissection depth index ranged from 0.320 to 0.972, and the 5th percentile was 0.503. The correlation coefficients were -0.305 (P=.0007), -0.259 (P=0.0111), 0.188 (P=0.0367), 0.189 (P=0.0359) respectively for male gender, the length of aortic dissection, atherosclerosis, and translamellar mucoid extracellular matrix accumulation.

CONCLUSIONS

In 95% of patients with aortic dissection, the depth of dissection plane is larger than 778 microns, and the dissection depth index is greater than 0.503. In other words, aortic dissection rarely occurs in the inner 50.3% of the aortic media. The dissection depth index is negatively correlated with male gender and the length of aortic dissection, and positively correlated with atherosclerosis and translamellar mucoid extracellular matrix accumulation.

Review of Malpractice Lawsuits in the Diagnosis and Management of Aortic Aneurysms and Aortic Dissections

OBJECTIVE

Aortic aneurysms and dissections are prevalent causes of morbidity and mortality. The management of aortic pathologies may be called into question in malpractice suits. Malpractice claims were analyzed to understand common reasons for litigation, medical specialties involved, patient injuries, and outcomes.

METHODS

Litigation cases in the Westlaw database from September 1st, 1987 to October 23 rd, 2019 were analyzed. Search terms included "aortic aneurysm" and "aortic dissection." Data on plaintiff, defendant, litigation claims, patient injuries, misdiagnoses, and case outcomes were collected and compared for aortic aneurysms, aortic dissections, and overall cases.

RESULTS

A total of 346 cases were identified, 196 involving aortic aneurysms and 150 aortic dissections. Physician defendants were emergency medicine (29%), cardiology (20%), internal medicine (14%), radiology (11%), cardiothoracic (10%) and vascular surgery (10%). Litigation claims included "failure to diagnose and treat" (61%), "delayed diagnosis and treatment" (21%), "post-operative complications after open repair" (10%) and "negligent post-operative care" (10%). Patients with aneurysms presented with abdominal (63%) and back pain (37%), while dissections presented with chest pain (78%), abdominal pain (15%), and shortness of breath (14%). Misdiagnoses included gastrointestinal (12%), other cardiovascular (9%), and musculoskeletal conditions (9%), but many were not specified (58%). Overall, 83% of cases were wrongful death suits. Injuries included loss of consortium (23%), emotional distress (19%), and bleeding (17%). In 53% of the cases, the jury ruled in favor of the defendant. 25% of cases ruled for the plaintiff. 22% of cases resulted in a settlement. The mean rewarded for each case was $1,644,590.66 (SD: $5,939,134.58; Range: $17,500-$68,035,462).

CONCLUSION

For aortic pathologies, post-operative complications were not prominent among the reasons why suits were brought forth. This suggests improvements in education across all involved medical specialties may allow for improved diagnostic accuracy and efficient treatment, which could then translate to a decrease in associated litigation cases.

Is the frozen elephant trunk technique justified for chronic type A aortic dissection in Marfan syndrome?

Background

Chronic type A aortic dissection (cTAAD) in Marfan syndrome (MFS) is rare. Surgical experience is limited and the role of frozen elephant trunk (FET) technique remains undefined. We seek to evaluate the safety and efficacy of the total arch replacement (TAR) and FET technique for cTAAD in MFS.

Methods

The clinical data of sixty-eight patients with MFS undergoing FET and TAR for cTAAD were analyzed.

Results

Mean age was 35.8±9.7 years and thirty-nine were male (57.4%). Operative mortality was 10.3% (7/68). Stroke occurred in one (1.5%), re-exploration for bleeding in five (7.3%), low cardiac output in four (5.9%), and acute renal failure in two (2.9%). Follow-up was complete in 100% (61/61) at mean 7.3±4.0 years. The false lumen was obliterated in 73.5% across FET and 50.0% in unstented descending aorta (DAo). Distal dilation occurred in twenty patients, six of whom underwent thoracoabdominal aortic replacement, one abdominal aortic replacement and one thoracic endovascular aortic repair (TEVAR). Late death occurred in five. At ten years, 59.8% were free from distal aortic dilation, and the incidences were 23.2% for death, 14.4% for distal reoperation, and 62.4% for reoperation-free survival. Predictors for operative mortality were extra-anatomic bypass [odds ratio (OR), 229.592; P=0.036], preoperative maximal size (DMax) of aortic sinuses (mm) (OR, 1.134; P=0.032) and cardiopulmonary bypass (CPB) time (minute) (OR, 1.061; P=0.041). Risk factors for aortic dilatation included patent false lumen at diaphragmatic hiatus [hazard ratio (HR), 5.374; P=0.008], preoperative DMax (mm) of proximal DAo (HR, 1.068; P=0.001) and renal arteries (HR, 1.102; P=0.005) which also predicted distal reoperation (HR, 1.149; P=0.001). The time from onset to operation (day) (HR, 1.002; P=0.004) and CPB time (minute) (HR, 1.032; P=0.036) predicted late death.

Conclusions

This study shows that the TAR and FET technique is a safe and durable approach to cTAAD in patients with MFS. The operation should be performed as early as possible to optimize clinical outcomes.

A machine learning model to classify aortic dissection patients in the early diagnosis phase

Aortic dissection is one of the most clinical-challenging and life-threatening cardiovascular diseases associated with high morbidity and mortality. Aortic dissection requires fast diagnosis and timely therapy. Any delay or misdiagnosis can cause severe consequence to aortic dissection patients with even higher mortality. To better help physicians identify the potential dissection within the scope of all misdiagnosed patients, this paper describes a method which is developed with data mining methods for aortic dissection patient classification and prediction in the phase of early diagnosis. Various machine learning algorithms were used to build the models which were all trained and tested on the patient dataset with cross validation. Among them, Bayesian Network model achieved the best performance by predicting at a precision rate of 84.55% with Area Under the Curve (AUC) value of 0.857. On this basis, the Bayesian Network model can help physicians better with early diagnosis of aortic dissection in clinical practice. Beyond this study, more data from diverse regions and the internal pathology can be crucial to further build a universal model with broader predictive power.

Transesophageal echocardiography evaluation of the thoracic aorta

Transesophageal echocardiography (TEE) can be used to identify risk factors such as aortic atherosclerosis [2] before any sort of surgical manipulations involving aorta and its related structures. TEE has become an important noninvasive tool to diagnose acute thoracic aortic pathologies. TEE evaluation of endoleaks helps early detection and immediate corrective interventions. TEE is an invaluable imaging modality in the management of aortic pathology. TEE has to a large extent improved the patient outcomes.

Surgical techniques in type A dissection

Acute aortic dissection is a surgical emergency that must be urgently managed, with the primary goal of restoring flow to the dominant true lumen in the downstream aorta. Our preference at the Cleveland Clinic is for an open distal anastomosis technique without aortic clamping, as it permits more accurate approximation of dissected layers and more homeostatically secure anastomosis. During this procedure we employ right axillary end-to-side graft perfusion, followed by deep hypothermic circulatory arrest and antegrade brain perfusion. The distal anastomosis is performed without felt strips or glue. Critical to achieving a successful outcome is meticulous de-airing of the arch, diligent myocardial protection, and a water-tight anastomosis prior to discontinuing cardiopulmonary bypass.

Svensson class IV Ascending aortic dissection, often confused with penetrating ulcer

TWe present the case of a 64 years old male patient who had recently suffered an infective aortic valve endocarditis (Streptococcus agalactiae) complicated by embolic arthritis of the right hip. Initial echocardiography revealed moderate aortic insufficiency developed on a tricuspid aortic valve with a small vegetation (5 mm × 4 mm) on the left coronary cusp. Furthermore, an aneurysmal dilatation of the ascending aorta (maximal diameter, 54 mm) was noted. Other heart valves and left ventricular function were considered normal. The patient completed a 4 weeks course of antibiotherapy, and the right hip arthritis was treated by drainage and synovectomy. The patient was subsequently referred to surgery on an outpatient basis for the aneurysm of the ascending aorta. Preoperative computed tomography showed localized aortic dissection of the tubular ascending aorta characterized by an intimal tear without medial hematoma but excentric bulging of the aortic wall. This lesion was initially considered a penetrating ulcer of the aortic wall The operative specimen allowed to make differential diagnosis with a penetrating aortic ulcer by showing that the lesion did not develop within an atherosclerotic plaque. However, downstream extension of the dissection was probably limited by the presence of transmural calcifications on its distal side. The patient underwent successful complete aortic root replacement using a stentless Freestyle bioprosthesis with Dacron graft extension as reported previously.

The role of multidetector-row CT in the diagnosis, classification and management of acute aortic syndrome

The term "acute aortic syndrome" (AAS) encompasses several non-traumatic life-threatening pathologies of the thoracic aorta presenting in patients with a similar clinical profile. These include aortic dissection, intramural haematoma and penetrating atherosclerotic ulcers. These different pathological entities can be indistinguishable on clinical grounds alone and may be confused with other causes of chest pain, including myocardial infarction. Multidetector-row CT (MDCT) is the current modality of choice for imaging AAS with a sensitivity and specificity approaching 100%. Early diagnosis and accurate radiological classification is associated with improved clinical outcomes in AAS. We review the characteristic radiological features of the different pathologies that encompass AAS and highlight the vital role of MDCT in determining the management of these life-threatening conditions.

Biomechanical factors in the biology of aortic wall and aortic valve diseases

The biomechanical factors that result from the haemodynamic load on the cardiovascular system are a common denominator of several vascular pathologies. Thickening and calcification of the aortic valve will lead to reduced opening and the development of left ventricular outflow obstruction, referred to as aortic valve stenosis. The most common pathology of the aorta is the formation of an aneurysm, morphologically defined as a progressive dilatation of a vessel segment by more than 50% of its normal diameter. The aortic valve is exposed to both haemodynamic forces and structural leaflet deformation as it opens and closes with each heartbeat to assure unidirectional flow from the left ventricle to the aorta. The arterial pressure is translated into tension-dominated mechanical wall stress in the aorta. In addition, stress and strain are related through the aortic stiffness. Furthermore, blood flow over the valvular and vascular endothelial layer induces wall shear stress. Several pathophysiological processes of aortic valve stenosis and aortic aneurysms, such as macromolecule transport, gene expression alterations, cell death pathways, calcification, inflammation, and neoangiogenesis directly depend on biomechanical factors.

Multidetector CT of Aortic Dissection: A Pictorial Review

Aortic dissection is the most common acute emergency condition of the aorta and often has a fatal outcome. Outcome is determined by the type and extent of dissection and the presence of associated complications (eg, cerebral sequelae, aortic branch involvement, pericardial involvement, and visceral involvement), with early diagnosis and treatment being essential for improved prognosis. Aortic dissections are classified on the basis of the site of the intimal tear according to the Stanford classification system. Type A aortic dissection involves the ascending thoracic aorta and may extend into the descending aorta, whereas in a type B dissection the intimal tear is located distal to the left subclavian artery. Type A dissection typically requires urgent surgical intervention, whereas type B dissection can often be treated medically. Modern multidetector computed tomography (CT) is a fast, widely available imaging modality with high sensitivity and specificity. Multidetector CT allows the early recognition and characterization of aortic dissection as well as determination of the presence of any associated complications, findings that are essential for optimizing treatment and improving clinical outcomes.

The diagnosis and management of aortic dissection

Aortic dissection represents the most common aortic emergency, affecting 3 to 4 per 100,000 people per year and is still associated with a high mortality. Twenty percent of the patients with aortic dissection die before reaching hospital and 30% die during hospital admission. Aortic dissections may be classified in 3 ways: according to their anatomical extent (the Stanford or DeBakey systems), according to the time from onset (acute or chronic), and according to the underlying pathology (the European Society of Cardiologists' system). Advances in endovascular technology have provided new treatment options. Hybrid endovascular and conventional open surgical repair represent the mainstay of treatment for acute type A dissection. Medical management remains the gold standard for acute and uncomplicated chronic type B dissection, though endovascular surgery offers exciting potential in the management of complicated type B dissection through sealing of the intimal entry tear.

Murine model of surgically induced acute aortic dissection type A

OBJECTIVES

This study aimed at developing a murine model of surgically induced acute aortic dissection type A for investigation of the formation and progression of acute aortic dissection and to test whether this system could be used for biomarker discovery.

METHODS

Adult fibrillin-1 deficient, Fbn1(C1039G/+) mice and wild-type mice were anesthetized, ventilated, and the ascending aorta exposed via hemisternotomy. We hypothesized that acute aortic dissection could be induced either by injecting autologous blood into the aortic wall or by injury to the wall with aortic clamping. Echocardiography was done preoperatively, and serum samples were collected before and 30 minutes after the operation and analyzed by enzyme-linked immunosorbent assay.

RESULTS

Echocardiography revealed larger aortic root diameters in Fbn1(C1039G/+) compared with wild-type mice (P = .001). Histologic examination showed that aortic clamp injury but not injection of blood leads to large intimal tears, disruption of aortic wall structures, and localized dissection of the aortic media in Fbn1(C1039G/+) mice. Acute aortic dissection developed in 4 of 5 Fbn1(C1039G/+) mice versus 0 of 5 wild-type mice after aortic clamping (P < .01). Elastin staining showed higher elastic fiber fragmentation and disarray in Fbn1(C1039G/+) compared with wild-type mice. Enzyme-linked immunosorbent assay analysis revealed elevated circulating transforming growth factor beta1 concentrations after induction of acute aortic dissection in Fbn1(C1039G/+) mice (P = .02, 150 +/- 61 ng/mL vs 456 +/- 97 ng/mL), but not in wild-type or sham-operated mice.

CONCLUSIONS

Aortic clamp injury can induce AAD in Fbn1(C1039G/+), but not in wild-type mice. This murine model of surgically induced acute aortic dissection is highly reproducible and nonlethal in the short term. Using this system, we revealed that circulating transforming growth factor beta1 is a promising biomarker for acute aortic dissection.

Pathophysiology, diagnosis, and management of aortic dissection

Aortic dissection is an uncommon but potentially fatal disease with catastrophic complications. A high level of suspicion is required for successful diagnosis as presenting symptoms are so variable that dissection may be overlooked in up to 39% of cases. It most commonly presents in the elderly population with a history of chronic hypertension. Rapid intervention is necessary as delay leads to higher mortality. Despite advances in diagnostic and therapeutic techniques, morbidity and mortality remains high. Advances in diagnostic imaging have raised the awareness of variants of aortic dissection, including intramural hemorrhage and penetrating aortic ulcer. This distinction is important as the clinical course of these variants differs from that of classical aortic dissection, and thus treatment may also differ. Understanding of these variants has also led to the recognition of markers that may help predict progression to classical aortic dissection and thus warrant closer vigilance in selected patient populations. The recognition that rapid diagnosis is required for management of aortic dissection has led to the investigation of serum tests as diagnostic aids. Serum smooth muscle myosin heavy chain, d-dimer, and serum soluble elastin fragments are promising tests that may help raise suspicion for the diagnosis of acute aortic dissection. The high mortality associated with surgical therapy has led to investigation of alternative approaches. Endovascular therapy has emerged as a viable option in patients with type B dissection who are too unstable for surgery. However, long-term follow up is required to validate this procedure.

Unexpected limited chronic dissection of the ascending aorta

We report a rare case of a limited chronic dissection of the ascending aorta that was accidentally discovered at operation performed for severe aortic stenosis and moderate to severe dilatation of the ascending aorta. Preoperative investigations such as transoesophageal echocardiography and cardiac catheterization missed the diagnosis of dissection. Intraoperative findings included a 3.5 cm eccentric bulge of the ascending aorta and a 5 mm circular shaped intimal tear comunicating with a limited hematoma or small dissection of the media layer. (The rarety of the report is that the chronic dissection is limited to a small area (approximatively 3.5 x 2.5 cm) of the ascending aorta).

Acute cardiovascular emergency: missed killer in the emergency room

Acute chest pain in hypertensive patients presenting to the emergency room constitute a wide spectrum of life threatening conditions including an acute aortic dissection. Acute Aortic syndromes constitute uncommon but lethal identities, with high morbidity and mortality requiring a high index of suspicion, appropriate diagnostic tools and urgent line of management. The authors are reporting a case of an elderly hypertensive lady, presenting with acute chest pain secondary to type B aortic dissection, which was missed on the initial presentation. The authors reviewed the current practice of diagnosing and managing acute aortic dissection.

Fluid-structure interaction within a layered aortic arch model

The response of wall stress to the elasticity of each layer in the aorta wall was investigated to understand the role of the different elastic properties of layers in the aortic dissection. The complex mechanical interaction between blood flow and wall dynamics in a three-dimensional arch model of an aorta was studied by means of computational coupled fluid-structure interaction analysis. The results show that stresses in the media layer are highest in three layers and that shear stress is concentrated in the media layer near to the adventitia layer. Hence, the difference in the elastic properties of the layers could be responsible for the pathological state in which a tear splits across the tunica media to near to the tunica adventitia and the dissection spreads along the laminar planes of the media layer where it is near the adventitia layer.

Endovascular treatment of type B aortic dissections

The purpose is to describe our experience with endovascular treatment of type B aortic dissections. Five patients were treated for complications following type B dissections like, false channel aneurysm formation, rupture and arterial obstruction. They were treated in general anaesthesia using a 'homemade' endoprosthesis or a commercially available endoprosthesis (Excluder) deployed during fluoroscopy. The patients have been followed at regular intervals with a median observation time of 18 months (range 12--36). One patient needed a secondary intervention due to dislodgement of the proximal stentgraft with haemorrhage into both the false and the true lumen. Otherwise there have been no early or late mortality or major complications in this series. Even if our experience with endovascular treatment of type B dissections is rather limited, the results so far are promising. Open surgery in many of these cases is complicated with high morbidity and mortality rate and the endovascular technique offers great advantages. A longer follow-up period is necessary to define the place of endovascular treatment.