Overview
Definition:
Thoracic Endovascular Aortic Repair (TEVAR) is a minimally invasive surgical procedure used to treat pathologies of the thoracic aorta, including aneurysms, dissections, and traumatic injuries
It involves the placement of a stent graft via a catheter inserted through the femoral artery, reinforcing the weakened aortic wall without requiring open thoracotomy.
Epidemiology:
Thoracic aortic aneurysms (TAA) are less common than abdominal aortic aneurysms (AAA), with an estimated prevalence of 5-10 per 100,000 person-years
Aortic dissections, particularly Type B, are serious medical emergencies with high mortality rates if untreated
TEVAR has become a preferred option for a growing number of patients with these conditions.
Clinical Significance:
TEVAR offers a less invasive alternative to traditional open surgical repair, leading to reduced perioperative morbidity and mortality, shorter hospital stays, and faster recovery
It expands treatment options for patients with high surgical risk who may not be candidates for open repair, significantly improving outcomes for complex thoracic aortic diseases.
Indications
Indications For Tevar:
Ruptured or symptomatic thoracic aortic aneurysms (TAA)
Thoracic aortic dissections (Stanford Type B, and selected Type A in specific centers)
Traumatic aortic injuries
Aortic arch pathologies involving the origin of great vessels (if anatomy is suitable)
Patients with prohibitive risk for open surgical repair.
Contraindications:
Unsuitable anatomy for stent graft deployment (e.g., inadequate sealing zones, tortuous iliac/femoral arteries, severe iliac occlusive disease)
Active infection
Patients with a life expectancy too short to benefit from the procedure
Extensive intramural hematoma in dissections without malperfusion.
Imaging Criteria:
Accurate measurement of aortic dimensions
Identification of proximal and distal landing zones (adequate healthy aorta for graft sealing)
Assessment of vessel tortuosity and diameter of access arteries
Evaluation of anatomical suitability for specific stent graft devices.
Preoperative Preparation
Patient Assessment:
Comprehensive cardiovascular assessment, including ECG, echocardiogram, and assessment of renal function
Detailed evaluation of access vessels (femoral/iliac arteries) using CTA or MRA
Risk stratification for anesthesia and the procedure.
Imaging Studies:
Computed Tomography Angiography (CTA) is the gold standard for anatomical assessment, providing detailed information on aneurysm/dissection morphology, landing zones, and access vessel characteristics
MRA may be used in patients with contraindications to contrast agents.
Informed Consent:
Discussing the procedure, potential benefits, risks (including endoleak, graft migration, stroke, spinal cord ischemia, device failure), alternatives (open surgery, medical management), and expected outcomes with the patient and family.
Procedure Steps
Access And Deployment:
Vascular access is typically achieved via bilateral femoral artery cutdowns or percutaneous femoral artery access
Guidewires are advanced into the thoracic aorta
The stent graft, pre-loaded on a delivery catheter, is then deployed precisely at the diseased segment of the aorta under fluoroscopic guidance.
Stent Graft Selection:
Selection of appropriate stent graft size (length and diameter) based on pre-operative imaging to ensure adequate sealing in healthy aorta proximal and distal to the pathology
Various devices are available for different aortic regions and pathologies.
Adjunctive Procedures:
Chimney grafts or fenestrations may be used to maintain flow to the supra-aortic branches (e.g., innominate, subclavian, carotid arteries) when these are involved in the pathology or occluded by the dissection
Balloon angioplasty or stenting of access vessels may be performed if necessary.
Postoperative Care
Immediate Monitoring:
Close monitoring of vital signs, hemodynamics, and urine output
Serial imaging (e.g., CTA) to assess graft deployment, rule out endoleaks, and evaluate for complications
Management of blood pressure is critical to minimize stress on the repair.
Medical Management:
Aspirin and a P2Y12 inhibitor (e.g., clopidogrel) are typically prescribed long-term to prevent graft thrombosis
Beta-blockers are often used to reduce aortic wall stress, especially in dissection cases
Pain management and antibiotic prophylaxis are standard.
Complication Surveillance:
Routine follow-up imaging (CTA or MRA) at 1 month, 6 months, and then annually or as needed, to monitor for endoleaks, graft migration, dilatation, or stenosis
Prompt intervention for any identified complications.
Complications
Early Complications:
Endoleak (Type I, II, III, IV, V)
Access site complications (hematoma, pseudoaneurysm, infection)
Hemorrhage
Stroke or transient ischemic attack (TIA)
Spinal cord ischemia (paraplegia)
Myocardial infarction
Graft migration or collapse.
Late Complications:
Late endoleaks
Graft infection
Degeneration of the stent graft material
Aortic rupture despite repair
Re-intervention due to graft failure or endoleak
Progressive dilatation of the aorta distal to the graft.
Prevention Strategies:
Meticulous patient selection and anatomical assessment
Optimal stent graft sizing and accurate deployment
Careful intraoperative management and imaging
Aggressive postoperative medical management (antiplatelets, antihypertensives)
Regular surveillance imaging.
Prognosis
Factors Affecting Prognosis:
The type and extent of aortic pathology (aneurysm vs
dissection)
Anatomical suitability for TEVAR
Patient comorbidities and surgical risk
Presence and type of endoleak
Technical success of the procedure
Adequacy of postoperative surveillance and management.
Outcomes:
TEVAR has demonstrated excellent short-term and durable long-term results for suitable patients, with significantly lower mortality and morbidity compared to open repair
Survival rates for uncomplicated TEVAR are generally high, with a substantial reduction in the risk of rupture.
Follow Up:
Lifelong surveillance is recommended for all patients treated with TEVAR
This typically involves periodic clinical evaluation and imaging studies to monitor the integrity of the repair and detect any potential complications early, enabling timely intervention.
Key Points
Exam Focus:
Understand indications for TEVAR, contraindications, and essential anatomical considerations for landing zones
Differentiate types of endoleaks and their management
Recall key imaging modalities (CTA) and their interpretation for TEVAR planning.
Clinical Pearls:
Adequate proximal and distal seal is paramount for successful TEVAR
consider "chimney" or "fenestrated" grafts for arch pathology
Postoperative blood pressure control is crucial to prevent graft failure and dissection propagation.
Common Mistakes:
Inadequate pre-operative imaging leading to suboptimal graft selection or deployment
Misinterpretation of endoleaks
Failure to initiate or adhere to lifelong surveillance protocols
Overlooking access vessel complications.