Diameter of the thoracic aorta 1.5 times greater than normal (or larger)Thoracoabdominal aneurysms, comprising approximately 10% of thoracic aneurysms, may be repaired with the use of a partial bypass of the left atrium to the femoral artery
Fusiform when the whole circumference is affected (ture)Saccular when only part of the circumference is involved. (false)
Aneurysms of the thoracic aorta can be classified into four general anatomic categories, although some aneurysms involve more than one segment :Ascending aortic aneurysms arise anywhere from the aortic valve to the innominate artery — 60 percentAortic arch aneurysms include any thoracic aneurysm that involves the brachiocephalic vessels — 10 percentDescending aortic aneurysms distal to the left subclavian artery — 40 percentThoracoabdominalaneurysms — 10 percent
According to the Crawford classification,a type I aneurysm originates distal to the left subclavian artery and involves the visceral arteries. Type II involves the entire aorta distal to the left subclavian artery; type III involves the distal half of the descending thoracic aorta and the entire abdominal aorta; andtype IV involves the infradiaphragmatic aorta. Types I and II are associated with the highest rates of mortality and paraplegia
1.Death from aneurysmal rupture is one of the 15 leading causes of death in most series. 3.. due to an increase in diagnosis based on the widespread use of imaging techniques4.. The prevalence of fatal and nonfatal rupture has also increased..5. Male to female 2-4:1
Aging results in changes in collagen and elastin.which lead to weakening of the aortic wall and aneurysmal dilation.According to the law of Laplace, luminal dilation results in increased wall tension and the vicious cycle of progressive dilation and greater wall stressArteriosclerotic (degenerative) disease is the most common cause of thoracic aneurysms.A previous aortic dissection with a persistent false channel.may produce aneurysmal dilation; such aneurysms are the second most common type. False aneurysms are more common in the descending aorta and arise from the extravasation of blood into a tenuous pocket contained by the aortic adventitia. Because of increasing wall stress, false aneurysms tend to enlarge over time5. Authorities strongly agree that genetics play a role in the formation of aortic aneurysms. Of first-degree relatives of patients with aortic aneurysms, 15% have an aneurysm .. This appears especially true in first-degree relatives of female patients with aortic aneurysm6.- Marfan syndrome is a potentially lethal connective-tissue disease characterized by skeletal, heart valve, and ocular abnormalities. Individuals with this disease are at risk for aneurysmal degeneration, especially in the thoracic aorta. Marfan syndrome is an autosomal dominant genetic condition that results in abnormal fibrillin, a structural protein found in the human aorta- Ehlers Danols type IV Type IV Ehlers-Danlos syndrome results in a deficiency in the production of type III collagen, and individuals with this disease may develop aneurysms in any portion of the aorta. Imbalances in the synthesis and degradation of structural proteins of the aorta have also been discovered, which may be inherited or spontaneous mutations.7. Atherosclerosis may play a role. Whether atherosclerosis contributes to the formation of an aneurysm or whether they occur concomitantly is not established. 8. Other causes of aortic aneurysms are infection (ie, bacterial [mycotic or syphilitic]), arteritis (ie, giant cell, Takayasu, Kawasaki, Behçet), and trauma. Aortitis due to granulomatous disease is rare, but it can lead to the formation of aortic and, on occasion, pulmonary artery aneurysms. Aortitis caused by syphilis may cause destruction of the aortic media followed by aneurysmal dilation. 9. The true etiology of aortic aneurysms is probably multifactorial, and the condition occurs in individuals with multiple risk factors. Risk factors include smoking, chronic obstructive pulmonary disease (COPD), hypertension, atherosclerosis, male gender, older age, high BMI, bicuspid or unicuspid aortic valves, genetic disorders, and family history. Aortic aneurysms are more common in men than in women and are more common in persons with COPD than in those without lung disease.
-These recommendations are based on the finding that the incidence of complications (rupture and dissection) exponentially increased when the size of the ascending aorta reached 6.0 cm (31% risk of complications) or when the size of the descending aorta reached 7.0 cm (43% risk)Symptomatic patients should undergo aneurysm resection regardless of size. Acutely symptomatic patients require emergent operation. Emergent operation is indicated in the setting of acute rupture. Rupture of the ascending aorta may occur into the pericardium, resulting in acute tamponade. Rupture of the descending thoracic aorta may cause a left hemothorax.Patients who undergo surgery for symptomatic aortic insufficiency or stenosis with an associated enlarged aneurysmal aorta should have concomitant aortic replacement if the aorta reaches 5 cm in diameter. Concomitant aortic replacement should be consider for patients with bicuspid aortic valves with an aorta >4.5 cm in diameter.
No absolute, mostly relative constrictions. Indivisualised, pt ability to have a major surgeryRisk/benefit ratioEndovascular stent grafting is less invasive is ideal alternative to open repair in these patientsPatients must understand that life-long follow-up is required and that long-term durability is unknown.
Chest radiographIn the case of ascending aortic aneurysms, chest x-rays may reveal a widened mediastinum, a shadow to the right of the cardiac silhouette, and convexity of the right superior mediastinum. Lateral films demonstrate loss of the retrosternal air space. However, the aneurysms may also be completely obscured by the heart, and the chest x-ray appear normal.Plain chest radiographs may show a shadow anteriorly and slightly to the left for arch aneurysms and posteriorly and to the left for descending thoracic aneurysms. Aortic calcification may outline the borders of the aneurysm in the anterior, posterior, and lateral views in both the chest and abdomen.EchocardiographyTransthoracic echocardiography demonstrates the aortic valve and proximal aortic root. It may help detect aortic insufficiency and aneurysms of the sinus of Valsalva, but it is less sensitive and specific than transesophageal echocardiography.Transesophageal echocardiography images show the aortic valve, ascending aorta, and descending thoracic aorta, but they are limited in the area of the distal ascending aorta, transverse aortic arch, and upper abdominal aorta. Transesophageal echocardiography can help accurately differentiate aneurysm and dissection, but the images must be obtained and interpreted by skilled personnel.Ischemia may be evaluated using dipyridamole-thallium or dobutamine echocardiography scans.UltrasonographyInfrarenal abdominal aortic aneurysms may be visualized using ultrasonography, but these images do not help define the extent for thoracoabdominal aneurysms.Carotid ultrasound may be needed for patients with carotid bruits, peripheral vascular disease, a history of transient ischemic attacks, or cerebrovascular accidents to evaluate for carotid disease.Intraoperative intravascular ultrasound (IVUS) can also be used to provide additional anatomical information and guidance during placement of endovascular stents.Intraoperative epiaortic ultrasound can be performed to scan the aorta for atherosclerotic disease or thrombus.For more information, see Bedside Ultrasonography, Abdominal Aortic Aneurysm.AortographyAortography images can delineate the aortic lumen, and they can help define the extent of the aneurysm, any branch vessel involvement, and the stenosis of branch vessels. It describes the takeoff of the coronary ostia.For patients older than 40 years or those with a history suggestive of coronary artery disease, aortography helps evaluate coronary anatomy, ventricular function by ventriculography, and aortic insufficiency. It does not help in defining the size of the aneurysm because the outer diameter is not measured, which may miss dissections.Disadvantages include the use of nephrotoxic contrast and radiation. The risk of aortography includes embolization from laminated thrombus and carries a 1% stroke risk.Computed tomography scanCT scans with contrast have become the most widely used diagnostic tool. They rapidly and precisely evaluate the thoracic and abdominal aorta to determine the location and extent of the aneurysm and the relationship of the aneurysm to major branch vessels and surrounding structures. They can help accurately determine the size of the aneurysm and assesses dissection, mural thrombus, intramural hematoma, free rupture, and contained rupture with hematoma.Sagittal, coronary, and axial images may be obtained with 3-dimensional reconstruction. Stent graft planning for endovascular descending thoracic aneurysm repairs requires fine-cut images from the neck through the pelvis to the level of the femoral heads. The takeoff of the arch vessels is critical to determine the adequacy of the proximal landing zone, as is assessing the patency of the vertebral arteries, if the left subclavian artery should be covered by the stent graft. Assessment of the common femoral artery access is essential to determine the feasibility of large-bore sheath access. A spiral CT scan with 1-mm cuts and 3-dimensional reconstruction with the ability to make centerline measurements is crucial to stent graft planning.Aortic size on imaging is widely used to guide clinical decision making in regards to patients who have thoracic aortic aneurysms. It has been found that the double-oblique plane yields improved agreement with planimetry and differed from the axial plane in proportion to aortic geometric obliquity; therefore, the double-oblique measurement is recommended.CT angiography may create multiplanar reconstructions and cines. This requires nephrotoxic contrast and radiation, but the procedure is noninvasive.Magnetic resonance imagingMRI and magnetic resonance angiography have the advantage of avoiding nephrotoxic contrast and ionizing radiation compared with CT scans.MRI and magnetic resonance angiography can also help accurately demonstrate the location, extent, and size of the aneurysm and its relationship to branch vessels and surrounding organs. These studies also precisely reveal aortic composition. However, they are more time consuming, less readily available, and more expensive than CT scans.Other TestsElectrocardiogram: Baseline ECG should be performed. Transthoracic echocardiograms noninvasively screen for valvular abnormalities and cardiac function.Diagnostic ProceduresCardiac catheterization: Patients with a history of coronary artery disease or those older than 40 years should undergo cardiac catheterization.Histologic FindingsHistologic findings may include elastic fiber fragmentation, loss of elastic fibers, loss of smooth muscle cells, cystic medial necrosis, intraluminal thrombus, and atherosclerotic plaque and ulceration.
Chest radiograph showing widening of the superior mediastinum.
Computed tomography scan depicting a descending thoracic aortic aneurysm with mural thrombus at the level of the left atrium.
Ascending aortogram showing ascending aortic aneurysm. The patient also underwent computed tomography scanning.
Computed tomography scan from a patient whose ascending aortogram showed an ascending aortic aneurysm.
A contrast enhanced CT demonstrating a large thoracic aneurysm of about 7 cm which has rupturedAtherosclerotic vascular dis-ease in an aortic aneurysm. Axial postcontrast image (window = 440, level = 40) reveals a large contrast collection projecting from the undersurface of the aortic arch, consistent with aneurysm (arrow). the low attention material within the aneurysm represents thrombus
Ruptured thoracic aortic aneurysm resulting in cutaneous haematoma
Chest radiograph in a patient with a thoracic aortic aneurysm following aneurysm surgery.
Descending thoracic aneurysms with the appropriate anatomy may now be repaired by endovascular stent grafts. The GORE TAG is an FDA-approved nitinol-based stent graft designed for descending thoracic aneurysm repair. An appropriate proximal neck of 2 cm prior to the aneurysm is required. Ideally, the proximal landing zone is beyond the left subclavian artery, though, in some circumstances, the stent may be placed proximal to the left subclavian artery. Distally, a sufficient landing zone of 2 cm prior to the celiac artery is required. The aortic inner neck diameters in the proximal and distal landing zones must fall within 23-37 mm. In addition, appropriately sized femoral and iliac arteries (typically >8 mm in diameter) that lack tortuosity and calcium are required for implantation. The GORE TAG graft has been FDA-approved since March 2005. More recently, the Zenith TX2 endovascular graft (Cook Medical Inc.; Bloomington, Ind) was approved in March 2008, followed by the Talent Thoracic Stent Graft (Medtronic Inc.; Minneapolis, Minn) in June 2008.[31, 32] The Valiant Thoracic Stent Graft (Medtronic Inc.; Minneapolis, Minn) is approved for use outside the United States.-------- Thoracoabdominal aneurysms, comprising approximately 10% of thoracic aneurysms, may be repaired with the use of a partial bypass of the left atrium to the femoral artery. Crawford type I thoracoabdominal aneurysms involve Dacron graft replacement of the aorta from the left subclavian artery to the visceral and renal arteries as a beveled distal anastomosis, using sequential cross-clamping of the aorta. Crawford type II thoracoabdominal aneurysm repair requires a Dacron graft from the left subclavian to the aortic bifurcation with reattachment of the intercostal arteries, visceral arteries, and renal arteries. Crawford type III or IV thoracoabdominal aneurysm repairs, which begin lower along the thoracic aorta or upper abdominal aorta, may use either the partial bypass of the left atrial artery to the femoral artery or a modified atrio-visceral and/or renal bypass. Prevention of paraplegia is one of the principal concerns in the repair of descending and thoracoabdominal aneurysms.Brain protectionMethods used for brain protection during deep hypothermic circulatory arrest (DHCA) include intraoperative EEG monitoring, evoked somatosensory potential monitoring, hypothermia (to temperatures < 20o C), packing the patient's head in ice, Trendelenburg positioning (ie, head down), mannitol, CO2 flooding, thiopental, steroids, and antegrade and retrograde cerebral perfusion.
Thoracic aortic aneurysm
Thoracic Aortic Aneurysm Al-Momtan, Ahmed Tahir B. E-6 Dr. Emad Hijazi
Background Anatomy and cardiac skeleton Histology of Blood vessels What is an aneurysm? And whats TAA? True vs False aneurysms Thoracic vs Abdominal Classification of thoracic aortic aneurysms Dissection .. Little talk.. Ayaman
Epidemiology Prevalence greater than 3-4%of those over 65 years. 6th-7th ..decade The estimated incidence of thoracic aortic aneurysms is 6 cases per 100,000 person-years. The overall prevalence of aortic aneurysms has increased significantly in the last 30 years..Causes? The prevalence of fatal and nonfatal rupture has also increased.. Males > females
Aetiology Aging population..Laplace law Arteriolosclerosis and HTN (60%) Smoking A previous aortic dissection with a persistent false channel. trauma False aneurysms Genetics (19%), CT, Females --FHx Connective tissue; Marfan’s (young), Ehler Danols. ATHEROSCLEROSIS! Does it? Bicuspid AV (52% have TA) Others; infxn, arteritis, trauma, aortitis Multifactorial? With risk factors (smoking, COPD high BMI…..)
Facts! 13% have multiple 20-25% with TA have and AAA.
Indications for surgery Elefteriades: (size) - 5.5 ascending aneurysms- No FHx e.g Marfan’s (5) - 6.5 descending aneurysms-No FHx (6) aortic aneurysm size in relation to body surface- ASI (aortic diameter in cm / body surface area (m2) --Risk - ASI < 2.75 cm/m2 low risk (4%/y) - ASI 2.75-4.25 cm/m2 moderate (8%/y) - ASI > 4.25 cm/m2 high risk (20-25%) Rapid expansion ( Growth rate) - 0.07 cm/y asc - 0.19 cm/y desc - If > 1cm/y >> repair! Symptomatic patients
Summary of indcations Aortic size Ascending aortic diameter ≥5.5 cm or twice the diameter of the normal contiguous aorta Descending aortic diameter ≥6.5 cm Subtract 0.5 cm from the cutoff measurement in the presence of Marfan syndrome, family history of aneurysm or connective tissue disorder, bicuspid aortic valve, aortic stenosis, dissection, patient undergoing another cardiac operation Growth rate ≥1 cm/y Symptomatic aneurysm Traumatic aortic rupture Acute type B aortic dissection with associated rupture, leak, distal ischemia Pseudoaneurysm Large saccular aneurysm Mycotic aneurysm Aortic coarctation Bronchial compression by aneurysm Aortobronchial or aortoesophageal fistula Relevant Anatomy
Contraindications for surgery Patients who have high morbidity and mortality; eg elderly with ESRD, respi insufficiency, cirhosis.. For descending ..ENDOVASCULAR stenting .. F/U ..
Treatment and Management Medical - Control HTN - Smoking cessation - Control other risk factors..
Surgical- Depends on the location, the extension, the patient comorbidities, the age, the staff, and the hospital setup!- Principally; TEE is needed for assessment of coronary artery bypass grafting!, the patient need of valve replacement or if the patients need valve sparing procedures.- Aortic arch aneurysms; comorbidities; neurologic injury (permenant), steroids are given at the onset of procedure if hypothermic circulatory aarrest is anticipated- Descending aneurysms; spinal complications, paraplagia, paraparessis– spinal arteriograms for reimplantation of Adankiewics artery!- Brain protection, DHCA, and intraoperative EEG monitoring, pacjing the patients head in ice, trendelenburg position, mannitol, CO2 flooding, thiopental, steroids, antergrade and retrograde cerebral perfusion.
Surgical Summary Dacron tube graft Ascending – may need to replace valve Arch – graft Descending – graft, stent grafts
Follow-up Development of another aneurysm postoperatively is not uncommon! Serial evaluations (CT, MRI –for ascending, arch or descending, echo for ascending) may be performed 3-6 months in 1st post-op year, and every 6 months thereafter. There was a difference in female and male patients undergoing thoracic endo repairs, FDA approved, females had higher rates of procedural complications, requiring more blood transfusions, longer hospital stay, more major adverse events after 30 days! BUT they are more often have successful
Outcome and prognosis Early hospital mortality following Asc TAA is 4-10%, stroke in 2-5% Arch aneurysms; mortality is 6-12%,, stroke 3-22%, renal failure requiring dialysis is 7% Descending; mortality is 12-15% overall; survivial rate is 60% at 5 years and 30-40% at 10 years Endovascular stenting stent grafting vs open surgery mortality is 3% and 14%, and operative mortality was 1% vs 6% Endovascular achieved shorter hospital stay, quicker recovery time and lower incidence of major adverse effects (except vascular compications. Endovascular complications at 2 years, 4% proximal stent migration, 6% migration of graft components and 15% had an endoleak! Survival rates between Endo and open groups are almost the same aat 2 years and 5 years (80% and 70%), no difference in rates of paraplagia!
Dacron tubeNataf P , Lansac E Heart 2006;92:1345-1352 Composite valve and graft replacemen
Natural History Yearly Rupture or Dissection Rates for Thoracic Aortic Aneurysms: Simple Prediction Based on Size 304 patients; 58.9% male; median age 65.8 Aneurysm size – 43.7% were 4.0-4.9 cm Location – 72% ascending Follow up – average 43.1 months End points Events No. Patients Dissection, rupture and death 2 Dissection, rupture (no death) 2 Dissection, death (no rupture) 5 Rupture and death (no dissection) 4 Rupture alone 5 Dissection alone 15 Death alone 44Davies RR, et al. Ann Thorac Surg 2002;73:17
Trials and comparisons ENDOVASCULAR STENT GRAFT TRIALS vs OPEN