Management of Thoracic aortic dissection type A

Management of Aortic dissection type A ! Aortic dissection aorta media false lumen aorta intimal tear entry site
! Aorta Ascending aorta, Aortic arch, Thoracic (descending) aorta, Abdominal aorta (1) ! tunica intima, tunica media, tunica adventitia (2)
1! ! ! ! ! ! ! ! ! ! 2
! 5.2 2.9 3.5 1 40-70 60
! aortic dissection ! 1. (Predisposing Factor) ! 1.1 75 aortic dissection ! 1.2 ! 1.3 (Connective tissue disease) Marfan syndrome, Ehlers-Danlos syndrome ! 1.4 Congenital cardiovascular abnormalities Bicuspid aortic valve, Coarctation of aorta ! ! 2. aorta (Direct trauma) ! 2.1 Blunt trauma decelerating injury aorta ! 2.2 Iatrogenic trauma ! ! 2.2.1 Intra-arterial catheterization ! ! 2.2.2 Intra-aortic balloon pump ! ! 2.2.3 aorta ! ! 2.2.4 aortic valve late dissection
! (Classification) ! Aortic dissection ! ! 1. ! 1.1 Acute Aorta ! 1.2 Chronic Aorta ! ! 2. (intimal tear) entry site aorta (Extension of aortic involvement) !
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! ! ! ! 3 aortic dissection
! intimal tear aorta media media aorta (antegrade propagation) (retrograde propagation) aorta pleural effusion pericardial effusion (5)
! dynamic force false lumen ! aortic dissection dissection ! 1. false lumen (extrinsic compression true lumen) ! 2. true lumen ! ! Proximal extension aortic dissection aortic root ! 1. Acute aortic regurgitation Aortic valve aortic wall ! 2.Myocardial infarction coronary artery
! ! 5! ! ! true lumen !
! ! ! ! ! ! ! ! 6 true false lumen
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1 aortic dissection ! complication ! ! 2.1 ! Acute aortic Regurgitation ! cardiac complication 41 76 aortic dissection type A congestive heart failure diastolic murmur ! Acute aortic regurgitation aortic dissection ! ! 2.1.1 aortic root false lumen aortic valve ! ! 2.1.2 aorta aortic root aortic valve valve leaflet prolapse ! ! 2.1.3 flap aortic valve aortic valve ! 2.2! Myocardial ischemia of infarction 7 false lumen coronary flap coronary artery ! EKG ! 2.3! Heart failure and shock 6 aortic insufficiency, acute myocardial ischemia or infarction cardiac tamponade ! 2.4! Pericardial effusion cardiac tamponade transudate false lumen pericardial space aortic dissection aorta pericardial space cardiac tamponade !
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! 7.Hemodynamic complication ! Hemodynamic status aortic dissection ! 1.Sudden death acute dissection massive myocardial infarction ! 2.Hypovolemic shock false lumen, acute aortic insufficiency, cardiac tamponade, hemothorax ! 3.Good hemodynamic status
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! !
! CT sensitivity 100 specificity 98 TEE sensitivity 98 specificity 95
! ! ! (stress) aorta beta-blocker , calcium channel blocker, ACEI systolic blood pressure 100-120 mmHg 60 ! sympathetic opiate analgesia ! hypotension false lumen, cardiac complication cardiac tamponade aortic valve regurgitation MI vasopressin inotropic drug adequate tissue perfusion vasopressin inotropic drug aorta sheering force stress aorta hemodynamic ! cardiac tamponade pericardiocentesis ! ! ! indication for surgery ! 1. acute proximal aortic dissection ! 2. chronic proximal aortic dissection ! ! 2.1 Aortic insufficiency ! ! 2.2 localized aneurysm ! ! 2.3 dissection ! 3. Acute distal aortic dissection ! ! 3.1 dissection ! ! 3.2 vital organ ! ! 3.3 dissection ! ! 3.4 localized aneurysm ! ! 3.5 ! ! 3.6 ! 4. Chronic distal aortic dissection ! ! 4.1 dissection ! ! 4.2 localized aneurysms ! 5. underlying marfan syndrome ! ! !
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! ! ! ! 9 11-13 c retrograde brain perfusion jugular vein brain perfusion pressure 20-40 mmHg antegrade brain perfusion brachiocephalic arteries brain perfusion pressure 50-80 mmHg2,8! ! ! ! ! ! ! ! ! ! !
dissection
Late complication late complication 1. dissection dissection 2. aortic insufficiency aortic valve replacement 3. aortic aneurysm
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! stress shearing force aorta volume consumption, cardiac out put aortic dissection 50 peripartum period 33 ! aortic dissection type A Type A aortic dissection Hypotermia ! Aortic dissection type A Aortic dissection !
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! aortic dissection
itoring, bedside TEE is preferred to avoid moving the patient out of the acute care environment (Figure 25, T11).
The most recent comparative study with nonhelical CT, 0.5 Tesla MR and TEE showed 100% sensitivity for all modalities, with better specificity of CT (100%) than for TEE and MR.44 A recent meta-analysis that evaluated the diagnostic accuracy of TEE, helical CT, and MR for suspected AoD found that all 3 imaging techniques provided equally reliable diagnostic val- ues.46 Accordingly, selection of an imaging modality is influ- enced by individual patient variables and institutional capabilities.
The diagnosis of acute AoD cannot be excluded defin- itively based on the results of a single imaging study.
Although TEE, CT, and MR are all highly accurate for the evaluation of acute AoD; false-negative studies can and do occur47 (Figures 9 and 15). If a high clinical suspicion exists for acute AoD but initial aortic imaging is negative, strongly consider obtaining a second imaging study (Fig- ure 25, T12).
8.6.3. Initial Management Once the diagnosis of AoD or one of its anatomic variants (IMH or PAU) is obtained, initial management is directed at limiting propagation of the false lumen by controlling aortic shear stress while simultaneously determining which patients will benefit from surgical or endovascular repair (Figure 26).
Figure 25. AoD evaluation pathway. ACS indicates acute coronary syndrome; AoD, aortic dissection; BP, blood pressure; CNS, central nervous system; CT, computed tomographic imaging; CXR, chest x-ray; EKG, electrocardiogram; MR, magnetic resonance imaging; STEMI, ST-elevation myocardial infarction; TAD; thoracic aortic disease; and TEE, transesophageal echocardiogram.
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to 39%) and, when present, were strongly suggestive of AoD (positive likelihood ratio 5.7; 95% CI 1.4 to 23)37 and predict increased risk. Of 513 cases of Type A dissection, patients with perfusion deficits were more likely to present with hypotension, shock, neurologic deficits, and tamponade and were more likely to have higher rates of hospital complica- tions and mortality (41% versus 25%, P!0.0002).246 Further- more, overall mortality rates correlated with the number of
pulse deficits present, likely as a reflection of the extent of vascular compromise and associated end-organ ischemia.246
Similarly, of 118 patients with Type A acute dissection, limb ischemia (defined as loss of pulse with associated pain and neurologic symptoms) was present in 38 cases (32%).247 The presence of limb ischemia was associated with an increased likelihood of other end-organ ischemia (ie, cerebral, visceral, or coronary) and a significant increase in overall mortality.247
Figure 22. Acute surgical management pathway for AoD. *Addition of ‘if appropriate’ based on Patel et al.226a AoD indicates aortic dis- section; CABG, coronary artery bypass graft surgery; CAD, coronary artery disease; TAD, thoracic aortic disease; and TEE, transesoph- ageal echocardiogram.
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8.6.3.1. Blood Pressure and Rate Control Therapy Aortic wall stress is affected by the velocity of ventricular contraction (dP/dt), the rate of ventricular contraction, and blood pressure. Initial medical stabilization using beta block- ers controls these 3 parameters by reducing heart rate and blood pressure to the lowest amounts that will still maintain adequate end-organ perfusion.61 Reasonable initial targets are a heart rate less than 60 bpm and a systolic blood pressure between 100 and 120 mm Hg.61
Intravenous propranolol, metoprolol, labetalol, or esmolol is an excellent choice for initial treatment. In patients who have a potential contraindication to beta blockade (eg, those with asthma, congestive heart failure, or chronic obstructive pulmonary disease), esmolol may be a viable option given its extremely short half-life. Use of labetalol, which is both an alpha- and beta-receptor antagonist, offers the advantage of potent heart rate and blood pressure control from a single agent, potentially eliminating the need for a secondary
Figure 26. Acute AoD management pathway. AoD indicates aortic dissection; BP, blood pressure; MAP, mean arterial pressure; and TTE, transthoracic echocardiogram.
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