UCSF Vascular & Endovascular Symposium 2015 UCSF Vascular & Endovascular Symposium 2015 UC SF UC SF TBAD Anatomy & Pathophysiology TBAD Anatomy & Pathophysiology DISCLOSURES � INDIVIDUAL CURRENT UNDERSTANDING: None � INSTITUTIONAL ANATOMY & PHYSIOLOGY Cook, Inc TYPE B AORTIC DISSECTION � Not discussing off-label use of anything UCSF Vascular & Endovascular Symposium 2015 UCSF Vascular & Endovascular Symposium 2015 UC SF UC SF TBAD Anatomy & Pathophysiology TBAD Anatomy & Pathophysiology ANATOMY ANATOMY � Medial degeneration characterized by • Smooth muscle cell loss • Fragmentation and depletion of elastic fibers • Accumulation of proteoglycans and glycosaminoglycans in cell depleted areas of the aortic wall 1
UCSF Vascular & Endovascular Symposium 2015 UCSF Vascular & Endovascular Symposium 2015 UC SF UC SF TBAD Anatomy & Pathophysiology TBAD Anatomy & Pathophysiology ANATOMY ANATOMY � Media consists of elastic fibers and vascular � Progression results from interplay of smooth muscle cells, interconnected by collagen • Hemodynamic stress fibers, proteoglycans, glycosaminoglycans and • Aortic injury various adhesive proteins � When functioning normally, these ECM • Chronic inflammation components • Genetic propensity • Impart elasticity & tensile strength • Epidemiologic risk factors • Sequester growth factors • Form structural interactions UCSF Vascular & Endovascular Symposium 2015 UCSF Vascular & Endovascular Symposium 2015 UC SF UC SF TBAD Anatomy & Pathophysiology TBAD Anatomy & Pathophysiology ANATOMY ANATOMY � All aortic media components show defects � All the usual inflammatory markers are present (T-cells, macrophages, cytokines) • Elastin—fibers, microfibrils, associated proteins & interface proteins � Hypoxia and increased oxidative stress • Collagen—increased expression, disordered � An excess of proteases (including MMPs) deposition � Pathologic signalling • Smooth muscle cells • TGF β � Apoptosis • Angiotensin II � Phenotype change • PG / GAG—content, function 2
UCSF Vascular & Endovascular Symposium 2015 UCSF Vascular & Endovascular Symposium 2015 UC SF UC SF TBAD Anatomy & Pathophysiology TBAD Anatomy & Pathophysiology ANATOMY ANATOMY Golledge et al, Lancet, 2008 Percentage 60% 10-15% 25-30% Type DeBakey I DeBakey II DeBakey III Stanford A Stanford B Proximal Distal Svensson et al, Circulation, 1999 UCSF Vascular & Endovascular Symposium 2015 UCSF Vascular & Endovascular Symposium 2015 UC SF UC SF TBAD Anatomy & Pathophysiology TBAD Anatomy & Pathophysiology ANATOMY ANATOMY INTIMAL TEAR � Location • Outer curve � less likelihood of retrograde extension � possibly less likelihood of late enlargement • Inner curve � greater likelihood of retrograde extension (only 15% with NO arch or ascending aortic involvement) 3
UCSF Vascular & Endovascular Symposium 2015 UCSF Vascular & Endovascular Symposium 2015 UC SF UC SF TBAD Anatomy & Pathophysiology TBAD Anatomy & Pathophysiology ANATOMY ANATOMY INTIMAL TEAR INTIMAL TEAR � Size / Number Caution • Less likelihood of late enlargement � How imaged � small entry tear (<10 mm) � How measured � multiple tears � Modeling vs in vivo • More likelihood of late enlargement � large entry tear � single / few tears � no distal tear UCSF Vascular & Endovascular Symposium 2015 UCSF Vascular & Endovascular Symposium 2015 UC SF UC SF TBAD Anatomy & Pathophysiology TBAD Anatomy & Pathophysiology ANATOMY ANATOMY LUMEN LOCATION, SHAPE & FLOW AORTIC DIAMETER � More likelihood of late enlargement Increased Risk Decreased Risk • Overall initial aortic diameter ≥ 40 mm True lumen True lumen • Proximal descending thoracic aortic false � Elliptical shape � Circular lumen lumen ≥ 22 mm False lumen False lumen • Initial diameter of the mid-thoracic aorta � Patent � Thrombosed � Partially thrombosed � Outer curve � Saccular � Inner curve 4
UCSF Vascular & Endovascular Symposium 2015 UCSF Vascular & Endovascular Symposium 2015 UC SF UC SF TBAD Anatomy & Pathophysiology TBAD Anatomy & Pathophysiology PHYSIOLOGY PHYSIOLOGY HEMODYNAMICS HEMODYNAMICS � Importance of false lumen pressure � Importance of false lumen pressure • BP control • HR control Onitsuka et al, J Thor Surg, 2003 Kodama et al, Circulation, 2008 UCSF Vascular & Endovascular Symposium 2015 UCSF Vascular & Endovascular Symposium 2015 UC SF UC SF TBAD Anatomy & Pathophysiology TBAD Anatomy & Pathophysiology PHYSIOLOGY PHYSIOLOGY HEMODYNAMICS HEMODYNAMICS � Static Obstruction � Static Obstruction • aortic stent-graft • branch stent • thrombectomy � Dynamic Obstruction � Dynamic Obstruction • aortic stent-graft • fenestration 5
UCSF Vascular & Endovascular Symposium 2015 UCSF Vascular & Endovascular Symposium 2015 UC SF UC SF TBAD Anatomy & Pathophysiology TBAD Anatomy & Pathophysiology PATHOPHYSIOLOGY PATHOPHYSIOLOGY GENETICS GENETICS 50 year old man, with Type B dissection, mild (one- � Syndromic drug) antecedent hypertension, no abnormal morphometrics, a cousin who had an aortic aneurysm (not dissection). He probably has 51% A. Hypertension-related sporadic TAD 31% B. Some form of Marfan’s 14% C. Some other genetic abnormality DeBacker et al, Ann 3% Cardiothor Surg, 2013 D. Bad luck s k ’ . n c . . u . a . . l p f b s r d a a a d M B e c t i t f a e l o n e r m e g - n r o o r f e s i h n e t e m o t r o e e S m p y o H S UCSF Vascular & Endovascular Symposium 2015 UCSF Vascular & Endovascular Symposium 2015 UC SF UC SF TBAD Anatomy & Pathophysiology TBAD Anatomy & Pathophysiology PATHOPHYSIOLOGY PATHOPHYSIOLOGY GENETICS GENETICS � Syndromic � Non-Syndromic genes related to SYNDROME GENE LOCATION smooth muscle Marfans Fibrillin 1 Mostly ascending aorta, aortic root; few descending aorta contractile function Loeys-Dietz 1 TGFBR1/2 Aortic root � Isolated / sporadic Ehlers-Danlos IV COL3A1 Mostly thoracic aorta and abdominal aorta Aneurysm-Osteoarthritis SMAD3 Mostly ascending aorta Turners syndrome 46X 15% are Type B eNOS 4a/b 90% Type A DeBacker et al, Ann polymorphism Cardiothor Surg, 2013 6
UCSF Vascular & Endovascular Symposium 2015 UCSF Vascular & Endovascular Symposium 2015 UC SF UC SF TBAD Anatomy & Pathophysiology TBAD Anatomy & Pathophysiology PATHOPHYSIOLOGY PATHOPHYSIOLOGY GENETICS GENETICS � Non-Syndromic � ACTA2 (12-21%) • About 50% have aortic events • Estimated that 20% of TAAD have a � Thoracic dissection genetic component � 25% mortality • Autosomal dominant � Type A > Type B • Interfamilial variability � Age of Type B < age at Type A • Arterial occlusive disease • Variable penetrance • Livedo reticularis • Variable severity • Dissect at diameter of 4.5-5.0 cm � TGF β 2 (4%) UCSF Vascular & Endovascular Symposium 2015 UCSF Vascular & Endovascular Symposium 2015 UC SF UC SF TBAD Anatomy & Pathophysiology TBAD Anatomy & Pathophysiology PATHOPHYSIOLOGY PATHOPHYSIOLOGY GENETICS GENETICS TGF β Arteriopathies � MYH11 (1-2%) Marfan’s abnormal fibrillin-1 failed sequestration of TGF β complex, resulting in increased • Patent ductus active TGF β & TGF β signalling • Dissect at diameter of 4.0-4.5 cm Loeys-Dietz TGFBR1 & 2 increased active TGF β � MLYK dissect with no enlargement Aneurysm/ SMAD gene abnormalities in the TGF β 2 ligand � FTAAD5 causes proteoglycan deposition Osteoarthritis ACTA2 increased TGF β signalling MYH11 increased TGF β signalling FTAAD5 increased PG deposition, ? caused by TGF β signalling 7
UCSF Vascular & Endovascular Symposium 2015 UCSF Vascular & Endovascular Symposium 2015 UC SF UC SF TBAD Anatomy & Pathophysiology TBAD Anatomy & Pathophysiology PATHOPHYSIOLOGY PATHOPHYSIOLOGY GENETICS GENETICS TGF β Arteriopathies Marfan’s abnormal fibrillin-1 failed sequestration of TGF β complex, resulting in increased active TGF β & TGF β signalling Loeys-Dietz TGFBR1 & 2 increased active TGF β Aneurysm/ SMAD gene abnormalities in the TGF β 2 ligand Osteoarthritis ACTA2 increased TGF β signalling MYH11 increased TGF β signalling FTAAD5 increased PG deposition, ? caused by TGF β signalling DeBacker et al, Ann Cardiothor Surg, 2013 UCSF Vascular & Endovascular Symposium 2015 UCSF Vascular & Endovascular Symposium 2015 UC SF UC SF TBAD Anatomy & Pathophysiology TBAD Anatomy & Pathophysiology PATHOPHYSIOLOGY PATHOPHYSIOLOGY GENETICS GENETICS Hiratzka et al, Circulation, 2010 Hiratzka et al, Circulation, 2010 8
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