Aortic Dissection Riya Chacko, MD November 4, 2009

Background Pathophysiology Imaging Modalities Management

Incidence 3/100,000 per year Men more likely to have aortic dissections compared to women 78% have chronic hypertension Peak for proximal dissection 50-55, distal At least 20% die before arriving at the hospital

Michael Ellis Debakey

High mortality rate: 25% during 1 st 24 hours, 70% in 1 st week, 80% at 2 weeks for proximal dissections, 10% in distal in 24 hours Acute versus chronic – present of symptoms within 2 weeks 30% are chronic 50% start in ascending aorta Khan et al. Chest 2002.

Death from: aortic rupture, aortic regurgitation, branch vessel rupture 75% of proximal untreated aortic dissections will rupture into pericardium, left pleural cavity, and mediastinum

Pathophysiology Medial degeneration Intimal tear

Disorders Associated with Increased Risk Hypertension Marfan’s – most common cause of dissection in patients <40 years of age Ehlers-Danlos syndrome Turner’s syndrome Biscupid aortic valve Cocaine Trauma Pregnancy Noonan syndrome Aortitis Aortic coarctation

Trauma

Double Barrel Sign – Aortic Disruption

Presentation Von Kodolitsch et al studied 3 variables: mediastinal widening, acute onset chest pain, and BP differential. Dissection probability high with any combo of 3 or isolated pulses/BP differential (>83%) Aortic pain 31% Mediastinal widening 39% Absence of all 37%

IRAD registry: Severe sharp pain 84.8% 31% nonspecific EKG changes 12.7% presented with syncope

Golledge et al. Lancet 2008.

Variants of Acute Aortic Syndromes Aortic intramural hematoma Aortic ulceration

Aortic intramural hematoma No intimal flap Rupture of vasa vasorum Occurs in 10-15% acute aortic syndromes Descending thoracic aorta Atherosclerosis Crescentic shape Can result in pseudoaneurysm High incidence of aortic rupture, prognosis SAME as dissection Ascending hematoma same risk as ascending dissection

Intramural Hematoma On TEE, see localized thickening of aortic wall >7 mm, echo-free spaces within the aortic wall, centrally displaced calcium, or absence of dissection flap/communication MRI can detect age of the hematoma (methemoglobin) 30-47% will lead to dissection, tamponade, or aortic rupture Pseudoaneurysm 20-45% Hematoma <1.0 cm better prognosis

Aortic Ulceration % of acute aortic syndromes Also seen in elderly patients with hypertension, severe atherosclerosis Descending thoracic aorta (AAA) Ulcer crater with thickened aortic wall extending from elastic lamina to media May lead to aneurysms and/or dilation Less commonly dissections Rare to have thromboembolism MRI most accurate 40% lead to aortic rupture

Khan et al. CHEST / 122 / 1 / JULY, 2002

Classification of Aortic Dissections Golledge et al. Lancet

Copyright ©2007 BMJ Publishing Group Ltd. Ince, H. et al. Heart 2007;93: Figure 1 Classification of distal or proximal aortic dissection. De Bakey: type I, originates in the ascending aorta, propagates at least to the aortic arch and often beyond it distally; type II, originates in and is confined to the ascending aorta; type III, originates in the descending aorta and extends distally down to the aorta or, rarely, retrograde into the aortic arch and ascending aorta. Stanford: type A, all dissections involving the ascending aorta, regardless of the site of origin; type B, all dissections not involving the ascending aorta. Adapted from Nienaber et al.3

Aortogram in a Patient with a Type A Aortic Dissection. The anterior view is shown. The well-opacified true lumen (T) and the poorly opacified false lumen (F) are separated by an intimal flap (I), which is visible in some parts of this image as a thin radiolucent line within the aorta. In addition, the proximal portions of both coronary arteries are well visualized. Cigarroa JE, Isselbacher EM et al. NEJM. Volume 328:35-43 January 7, 1993 Number 1January 7, 1993

Ascending aortic dissections posterior and to the right, above the right coronary artery ostium Descending aortic dissections posterior and to the left, more commonly affecting left renal and left iliofemoral arteries

Organ Involvement Cardiovascular Neurologic

The left oblique view is shown. The aortic root is dilated. The true lumen (T) and the false lumen (F) are separated by a faintly visible radiolucent line, which is the intimal flap (I). Note the abundance of contrast agent in the left ventricle (LV), which is indicative of substantial aortic insufficiency.

Cardiac Involvement Aortic regurgitation in 18-50% Pericardial effusion most commonly from transudation of fluid through intact false lumen, NOT rupture or leak Regional wall motion abnormalities % due to low coronary perfusion 38% of patients have pulse differential (right and left arm) 31-60% have EKG changes

Mechanism of Aortic Regurgitation

Neurologic Involvement Stroke 5-10% of all aortic dissections Spinal cord ischemia in 10% with distal involvement Intercostal arteries, artery of Adamkiewicz and thoracic radicular arteries

The Aortic Dissection Distinguishing true and false lumen  False lumen has spontaneous echo contrast with delayed/reverse flow  Thrombus only in false lumen – usually distal to entry site  True lumen expands during systole, compressed during diastole  False lumen usually larger (not always true)  Color flow: true lumen forward systolic flow, false lumen variable

Thrombus in False Lumen

Imaging Modalities To Assess Dissections CT MRI TEE TTE

Goals of Imaging

Barbant et al reported in 1992 results from CT, MRI and TEE PPV for all three in high-risk patients >85% In low-risk patients, PPV <50% for CT and TEE but 100% for MRI NPV high for all three >85%

Cigarroa JE, Isselbacher EM et al. NEJM. Volume 328:35-43 January 7, 1993 Number 1January 7, 1993

CT Sensitivity for ascending aorta <80% but up to 94% in descending and % specific overall Limitations: use of IV contrast, identifying intimal tear, branch vessel involvement, aortic regurgitation Helical CT superior

MRI Sensitivity and specificity % Limitations: lack of immediate availability, scan timing, restricted vitals monitoring

MRI of the Ascending Aorta in a Patient with a Type A Aortic Dissection. The coronal plane is shown. The aortic root (AR) and the pulmonary artery (P) are visualized. In the ascending aorta an intimal flap (I) separates the true (T) and false (F) lumens.

TTE Sensitivity 35-80% Specificity 39-96%

Xray 30-60% have mediastinal widening Bulges to the right with ascending and left with descending Left pleural effusion

TEE Sensitivity 98% Specificity 63-96% Identifies: entry site with intimal flap, thrombus, abnormal flow, involvement of coronary and arch vessels, pericardial effusion, aortic valve regurgitation, left ventricular function Limitations: operater experience, limited to thoracic and proximal abdominal aorta (cannot see below the celiac trunk), also “blind spot” proximal aortic arch where trachea and left mainstem bronchus along between esophagus and aorta

Methods by TEE of Assessing Aorta Understand relationship of aorta to esophagus – distal arch, aorta is anterior to the esophagus, at diaphragm aorta is posterior to the esophagus Communicating location – try to identify relative to known surgical structures (ie aortic valve, subclavian artery) versus incisors (less helpful to surgeons, helpful for serial exams) Focus on area just above aortic valve (Type A) and area just beyond left subclavian (Type B) Difficult to assess distal aortic arch because of trachea (between aorta and esophagus)

Ascending Aorta cm from incisors Start at 0 ME 5 chamber view Spin to for AV short axis Spin to AV long axis – measure sinus of Valsalva and ST junction Slowly withdraw to see additional 2-3 cm of ascending aorta Beware of swan catheters (artifact) Decrease to 60 then 0 and withdraw

Descending Aorta Adjust depth to 6-8 cm so descending aorta enlarged Advance to stomach, rotate and spin to 90 degrees, slowly withdraw gradually rotating

Intimal tear in 70% of dissections occurs 1-3 cm above sinus of Valsalva 20-30% at ligamentum arteriosum Entry site can be identified 88% of the time (Adachi et al.)

Differentiating Intimal Tear vs. Reverberation Intimal TearReverberation Undulates with cardiac cycle Distinct borders Crosses anatomic borders Blurred borders Does NOT undulate

Preferred Imaging Modalities Moore, A. et al. Am J Cardiology, 89: , 2002

Medical Treatment B-blocker + nitroprusside (Beta-blocker 1 st ) or Labetalol (alpha and beta-blocker)

Surgical Treatment Operative mortality 5- 10%, higher if complications present Goal is to replace the ORIGIN of dissection, not entire involved segment Mortality of surgery higher than medical therapy in Type B dissections 15% treated surgically require a 2 nd operation

Copyright ©2007 BMJ Publishing Group Ltd. Ince, H. et al. Heart 2007;93: Figure 2 Fourteen-day mortality in 645 patients from the International Registry of Aortic Dissection (IRAD) registry stratified by medical and surgical treatment in both type A and B aortic dissection. Adapted from Hagan et al.1

Endovascular Stents Success rate of % with 25% 30- day mortality Palliative or those unsuitable for surgery 13% of aortic dissections receive stents

Proximal Dissection Followup 65-80% survival if treated at 5 years 40-50% at 10 years

Distal Dissection Follow up 75% survival regardless of medical/surgical management if treated