Transcript Aortic Dissection - CareGroup Portal

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
60-70
At least 20% die before arriving at the
hospital
Michael Ellis Debakey
1908-2008
http://www.nytimes.com/2008/07/13/health/13debakey.html?pagewanted=1&_r=1
High mortality rate: 25% during 1st 24
hours, 70% in 1st 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
 2.3-7.6% 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. 2008.
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
Ince, H. et al. Heart 2007;93:266-270
Copyright ©2007 BMJ Publishing Group Ltd.
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 1
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 1015% 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 1
CT
Sensitivity for ascending aorta <80% but
up to 94% in descending and 87-100%
specific overall
Limitations: use of IV contrast, identifying
intimal tear, branch vessel involvement,
aortic regurgitation
Helical CT superior
MRI
Sensitivity and specificity 95-100%
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
 30-35 cm from incisors
 Start at 0 ME 5 chamber view
 Spin to 40-60 for AV short axis
 Spin to 90-120 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 Tear
Reverberation
Undulates with cardiac cycle
Crosses anatomic borders
Distinct borders
Blurred borders
Does NOT undulate
Preferred Imaging Modalities
Moore, A. et al. Am J Cardiology, 89:1235-1238, 2002
Medical Treatment
B-blocker + nitroprusside (Beta-blocker
1st) or
Labetalol (alpha and beta-blocker)
Surgical Treatment
 Operative mortality 510%, 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 2nd operation
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
Ince, H. et al. Heart 2007;93:266-270
Copyright ©2007 BMJ Publishing Group Ltd.
Endovascular Stents
 Success rate of 76100% with 25% 30day 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