Aortic dissection overview: Difference between revisions

Jump to navigation Jump to search
Shankar Kumar (talk | contribs)
Shankar Kumar (talk | contribs)
No edit summary
Line 7: Line 7:


[[Acute]] [[aortic]] dissection is the most common fatal condition that involves the [[aorta]]. The [[mortality]] rate has been estimated to be as high as 1% per hour during the first 48 hours. Because of the diverse clinical manifestations of [[aortic]] dissection, one needs to maintain a high index of suspicion in patients with not just [[Ddx:Chest Pain|chest pain]], but also those with [[stroke]], [[congestive heart failure]], [[hoarseness]], [[hemoptysis]], [[claudication]], [[superior vena cava (SVC) syndrome]], or upper airway obstruction. Despite the fact that a noninvasive [[diagnosis]] can be made in up to 90% of cases, the correct antemortem [[diagnosis]] is made less than 50% of the time. Recognition of the condition and vigorous pre-operative management are critical to survival.
[[Acute]] [[aortic]] dissection is the most common fatal condition that involves the [[aorta]]. The [[mortality]] rate has been estimated to be as high as 1% per hour during the first 48 hours. Because of the diverse clinical manifestations of [[aortic]] dissection, one needs to maintain a high index of suspicion in patients with not just [[Ddx:Chest Pain|chest pain]], but also those with [[stroke]], [[congestive heart failure]], [[hoarseness]], [[hemoptysis]], [[claudication]], [[superior vena cava (SVC) syndrome]], or upper airway obstruction. Despite the fact that a noninvasive [[diagnosis]] can be made in up to 90% of cases, the correct antemortem [[diagnosis]] is made less than 50% of the time. Recognition of the condition and vigorous pre-operative management are critical to survival.
 
==Historical Perspective==
DeBakey and Cooley reported the first successful operation for resection and [[graft]] replacement of the [[ascending aorta]] using [[cardiopulmonary bypass]] in 1956.
==Classification==
==Classification==
Several different classification systems have been used to describe [[aortic]] dissections. The systems commonly in use are either based on either the [[anatomy]] of the dissection ([[proximal]], [[distal]]) or the duration of onset of [[symptom]]s ([[acute]], [[chronic]]) prior to presentation.
Several different classification systems have been used to describe [[aortic]] dissections. The systems commonly in use are either based on either the [[anatomy]] of the dissection ([[proximal]], [[distal]]) or the duration of onset of [[symptom]]s ([[acute]], [[chronic]]) prior to presentation.
===DeBakey Classification System===
The DeBakey system is an [[anatomy|anatomical]] description of the [[aortic]] dissection. It categorizes the dissection based on where the original [[intima]]l tear is located and the extent of the dissection (localized to either the [[ascending aorta]] or [[descending aorta]], or involves both the ascending and descending [[aorta]].<ref>DeBakey ME, Henly WS, Cooley DA, Morris GC Jr, Crawford ES, Beall AC Jr. Surgical management of dissecting aneurysms of the aorta. ''J Thorac Cardiovasc Surg'' 1965;49:130-49. PMID 14261867.</ref>
*''Type I'' - Originates in [[ascending aorta]], propagates at least to the [[aortic arch]] and often beyond it [[distal]]ly.
*''Type II'' – Originates in and is confined to the [[ascending aorta]].
*''Type III'' – Originates in [[descending aorta]], rarely extends [[proximal]]ly.
{| border="1" cellspacing="0" style="width:320px;float:Center;margin-left:0.5em;border-collapse:collapse"
|-
|valign="top"|
|[[Image:AoDissect DeBakey1.png|90px]]
|[[Image:AoDissect DeBakey2.png|90px]]
|[[Image:AoDissect DeBakey3.png|90px]]
|-
|bgcolor="#DCDCDC"|Percentage
|align="center" bgcolor="#DCDCDC"|60&nbsp;%
|align="center" bgcolor="#DCDCDC"|10-15&nbsp;%
|align="center" bgcolor="#DCDCDC"|25-30&nbsp;%
|-
|style="border-bottom:white"|Type
|align="center" border="0"|DeBakey I
|align="center" |DeBakey II
|align="center" |DeBakey III
|-
|style="border-bottom:white"|
| colspan=2 align="center" |Stanford A
|align="center" |Stanford B
|-
|&nbsp;
| colspan=2 align="center" |Proximal
|align="center" |Distal
|-
| colspan=4 bgcolor="#ABCDEF" | <small>Classification of aortic dissection</small>
|}
===Stanford Classification System===
Divided into 2 groups; A and B depending on whether the ascending [[aorta]] is involved.<ref>Daily PO, Trueblood HW, Stinson EB, Wuerflein RD, Shumway NE. Management of acute aortic dissections. ''Ann Thorac Surg'' 1970;10:237-47. PMID 5458238.</ref>
*''A'' = ''Type I'' and ''II'' DeBakey
*''B'' = ''Type III'' Debakey
==Pathophysiology==
==Pathophysiology==
===Initial Intimal Tear===
[[Aortic]] dissection begins as a tear in the [[aortic]] wall in > 95% of patients. The tear is usually transverse, extends through the [[intima]] and halfway through the [[tunica media|media]] and involves ~50% of the [[aortic]] circumference. Two thirds of dissections originate in the [[ascending aorta]], and 20% are in the [[proximal]] [[descending aorta]].
* [[Aortic]] dissection begins as a tear in the [[aortic]] wall in > 95% of patients.  
*It is usually transverse, extends through the [[intima]] and halfway through the [[tunica media|media]] and involves ~50% of the [[aortic]] circumference.
 
Location of dissections:
:*The initial tear is usually within 100 mm of the [[aortic valve]].
:*65% of dissections originate in the [[ascending aorta]], distal to the [[aortic valve]] and [[coronary ostia]]
:*10% arise in the [[transverse aortic arch]]
:*20% in the [[proximal]] [[descending aorta]]
:*5% in the more [[distal]] [[descending aorta]]
 
===Propagation of the Intimal Tear===
In an [[aortic]] dissection, blood penetrates the ''[[intima]]'' and enters the ''[[tunica media|media]]'' layer. The high pressure rips the [[biological tissue|tissue]] of the ''[[tunica media|media]]'' apart, allowing more blood to enter. This can propagate along the length of the [[aorta]] for a variable distance, dissecting either towards or away from the [[heart]] or both.
Once a tear develops, blood then passes into the [[tunica media|media]], and a [[false lumen]] is dissected in the outer layer of [[aortic]] [[tunica media|media]] involving ~50% of the [[aortic]] circumference. This [[false lumen]] can enlarge, and compress the true [[lumen]], as well as extend [[proximal]]ly or [[distal]]ly and occlude [[aortic]] branches. For some unknown reason, the right [[lateral]] wall of the [[ascending aorta]] is the most common site for dissection. The [[right coronary artery]] can become occluded as a result of this propagation.
 
Separating the [[false lumen]] from the true [[lumen]] is a layer of [[intima]]l tissue. This [[tissue]] is known as the ''[[intima]]l flap''. As blood flows down the [[false lumen]], it may cause secondary tears in the [[intima]]. Through these secondary tears, the blood can re-enter the true [[lumen]].
 
==Causes==
==Causes==
Age related changes due to [[atherosclerosis]] and [[hypertension]] are associated with spontaneous dissection, while blunt trauma injury and sudden deceleration in a motor vehicle accident is a major cause of [[aortic]] dissection.
Age related changes due to [[atherosclerosis]] and [[hypertension]] are associated with spontaneous dissection, while blunt trauma injury and sudden deceleration in a motor vehicle accident is a major cause of [[aortic]] dissection.
Other risk factors and conditions associated with the development of aortic dissection include:
*[[Aging]]
*[[Bicuspid aortic valve]]
*[[Chest trauma]]
*[[Coarctation of the aorta]]
*[[Connective tissue disorders]]
*[[Ehlers-Danlos syndrome]]
*[[Heart surgery]] or procedures
*[[Marfan syndrome]]
*[[Third trimester of pregnancy]]
*[[Pseudoxanthoma elasticum]]
*[[Tertiary syphilis]]
*[[Turner's syndrome]]
*[[Vascular]] [[inflammation]] due to conditions such as [[arteritis]] and [[syphilis]]
==Differentiating Aortic Dissection from other Diseases==
==Differentiating Aortic Dissection from other Diseases==
[[Aortic]] dissection is a life threatening entity that must be distinguished from other life threatening entities such as [[cardiac tamponade]], [[cardiogenic shock]], [[myocardial infarction]], and [[pulmonary embolism]]. An [[aortic aneurysm]] is not synonymous with [[aortic]] dissection. [[Aneurysm]]s are defined as a localized permanent [[dilation]] of the [[aorta]] to a diameter > 50% of normal. Other disorders that [[aortic]] dissection should be differentiated from include the following:
[[Aortic]] dissection is a life threatening entity that must be distinguished from other life threatening entities such as [[cardiac tamponade]], [[cardiogenic shock]], [[myocardial infarction]], and [[pulmonary embolism]]. An [[aortic aneurysm]] is not synonymous with [[aortic]] dissection. [[Aneurysm]]s are defined as a localized permanent [[dilation]] of the [[aorta]] to a diameter > 50% of normal.
 
* [[Aortic Regurgitation]]
* [[Aortic Stenosis]]
* [[Cardiac Tamponade]]
* [[Cardiogenic Shock]]
* [[Gastroenteritis]]
* [[Hemorrhagic Shock]]
* [[Hernias]]
* [[Hypertensive Emergencies]]
* [[Hypovolemic Shock]]
* [[Mechanical Back Pain]]
* [[Myocardial Infarction]]
* [[Myocarditis]]
* [[Myopathies]]
* [[Pancreatitis]]
* [[Pericarditis]]
* [[Peripheral Vascular Injuries]]
* [[Pleural Effusion]]
* [[Pulmonary Embolism]]
* [[Thoracic Outlet Syndrome]]
 
==Epidemiology and Demographics==
==Epidemiology and Demographics==
There are approximately 2,000 cases of [[aortic]] dissection in the US per year, and [[aortic]] dissection accounts  for 3-4% of [[sudden deaths]]. The peak [[incidence]] is in the sixth and seventh decades, and males predominate 2:1.
There are approximately 2,000 cases of [[aortic]] dissection in the US per year, and [[aortic]] dissection accounts  for 3-4% of [[sudden deaths]]. The peak [[incidence]] is in the sixth and seventh decades, and males predominate 2:1.
== Risk Factors ==
== Risk Factors ==
* [[Aging]]. The highest [[incidence]] of [[aortic]] dissection is in individuals who are 50 to 70 years old.
[[Aging]], [[atherosclerosis]], [[diabetes]], [[hypertension]] and [[trauma]] are common risk factors for aortic dissection. Uncommon risk factors include [[bicuspid aortic valve]], [[cocaine]], [[coarctation of the aorta]], [[cystic medial necrosis]], [[Ehlers-Danlos syndrome]], [[giant cell arteritis]], [[heart surgery]], [[Marfan’s syndrome]], [[Pseudoxanthoma elasticum]], [[Turner's syndrome]], [[tertiary syphilis]] and the [[third trimester of pregnancy]].
* [[Atherosclerosis]] and its associated risk factors like [[diabetes]]
==Natural History, Complications and Prognosis==
* [[Bicuspid aortic valve]] is present in approximately 7%-14% of patients. These individuals are prone to dissection in the [[ascending aorta]]. The risk of dissection in individuals with [[bicuspid aortic valve]] is not associated with the degree of [[aortic stenosis|stenosis]] of the [[valve]].
[[Aortic]] dissection carries a very poor [[prognosis]]. 90% of patients who are untreated will be dead at one year. Type A dissection is associated with a worse [[prognosis]] than type B dissection. [[Aortic]] dissection can be complicated by extension to the [[coronary artery|coronary arteries]] resulting in [[myocardial infarction]], involvement of the [[aortic arch]] to cause [[stroke]], dilation of the route to cause [[aortic insufficiency]], extension into the [[pericardium]] to cause [[pericardial tamponade]], and [[heart failure]], and [[aortic rupture]].
* [[Chest trauma]]. Chest trauma leading to [[aortic]] dissection can be divided into two groups based on etiology: blunt chest trauma (commonly seen in car accidents) and [[iatrogenic]]. [[Iatrogenic]] causes include trauma during [[cardiac catheterization]] or due to an [[intra-aortic balloon pump]].
==Diagnosis==
* [[Cocaine abuse]]
===History and Symptoms===
* [[Coarctation of the aorta]]
* [[Cystic medial necrosis]]
* Deceleration [[trauma]] most commonly causes [[aortic rupture]], not dissection
* [[Ehlers-Danlos syndrome]]
* [[Giant cell arteritis]]
* [[Heart surgery]] particularly [[aortic valve replacement]]; 18% of individuals who present with an [[acute]] [[aortic]] dissection have a history of open [[heart surgery]]. Individuals who have undergone [[aortic valve replacement]] for [[aortic insufficiency]] are at particularly high risk. This is because [[aortic insufficiency]] causes increased blood flow in the [[ascending aorta]]. This can cause [[dilatation]] and weakening of the walls of the [[ascending aorta]].
* [[Hypertension]] is seen in 71-86% of patients. It occurs most frequently in those with type III dissection.
* Male gender. The [[incidence]] is twice as high in males as in females (male-to-female ratio is 2:1).
* [[Marfan’s syndrome]] is present in 5%-9% of patients. In this subset, there is an increased [[incidence]] in young individuals. Individuals with [[Marfan syndrome]] patients are more prone to [[proximal]] dissections of the [[aorta]].
* [[Pseudoxanthoma elasticum]]
* [[Turner's syndrome]]. [[Turner syndrome]] increases the risk of [[aortic]] dissection as a result of [[aortic root dilatation]]<ref>[http://www.ncbi.nlm.nih.gov/sites/entrez?Db=PubMed&Cmd=ShowDetailView&TermToSearch=17055808&ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum Increased maternal cardiovascular mortality associated with pregnancy in women with Turner syndrome.]</ref>.
* [[Tertiary syphilis]]
* [[Third trimester of pregnancy]]. Half of dissections in females before age 40 occur during [[pregnancy]] (typically in the 3rd trimester or early [[postpartum]] period).
* [[Vasculitis]] ([[inflammation]] of an [[artery]]) is rarely associated with [[aortic]] dissection.
 
== Natural History ==
If the patient remains untreated, the [[mortality]] is:
* 1% per hour during the first day
* 75% at 2 weeks
* 90% at 1 year
 
==Complications==
The complications of aortic dissection include:
=== Cardiac===
* [[Aortic rupture]] leading to [[massive blood loss]], [[hypotension]] and [[shock]] often resulting in death. Indeed, [[aortic]] dissection accounts  for 3-4% of [[sudden deaths]].
*[[Pericardial tamponade]] due to extension of the dissection into the [[pericardium]]
*[[Acute aortic regurgitation]]due to the [[aortic]] [[dilation]] and dissection into the [[valve]] structure which can then cause [[acute]] [[pulmonary edema]]
*[[Myocardial ischemia]] or [[myocardial infarction]] due to dissection into either the right or left [[coronary]] [[ostium]] (but most commonly the [[right coronary artery]])
*Redissection and [[aortic]] diameter enlargement
*[[Aneurysm]]al [[dilatation]] and [[saccular aneurysm]] [[chronic]]ally
 
===Kidney===
*[[Mesenteric]] and [[renal ischemia]]  due to dissection into the [[ostium]] of the parent [[vessel]]s which can lead to [[hematuria]], [[renal infarction]], [[acute renal failure]], or [[visceral]] [[ischemia]]
 
===Peripheral Arterial===
*[[Claudication]] due to an extension of the dissection into the [[iliac arteries]]
 
===Neurologic===
*[[Ischemic]] [[cerebrovascular accident]] ([[CVA]]) due to dissection into the head [[vessel]]s
*[[Hemiplegia]] due to dissection into the [[spinal cord|spinal]] [[artery|arteries]]
*[[anesthesia|Hemianesthesia]] due to dissection into the [[spinal cord|spinal]] [[artery|arteries]]
 
=== Compression of Nearby Organs===
*[[Swelling]] of the neck and face (compression of the [[superior vena cava]] or [[Superior vena cava syndrome]])
*[[Horner syndrome]] (compression of the [[superior cervical ganglia]])
*[[Dysphagia]] (compression of the [[esophagus]])
*[[Stridor]] and [[wheezing]] (compression of the airway)
*[[Hemoptysis]] (compression of and erosion into the [[bronchus]])
*[[Vocal cord paralysis]] and [[hoarseness]] (compression of the [[recurrent laryngeal nerve]])
 
==Prognosis==
The [[mortality]] rate is in large part determined by the patient's age and [[comorbidity|comorbidities]].
 
*30% in hospital [[mortality]]
*60% 10-year survival rate among treated patients
 
Type A [[aortic]] dissection
*[[surgery|Surgical]] treatment-30% [[mortality]] rate
*Medical treatment-60% [[mortality]] rate
Type B [[aortic]] dissection
*[[surgery|Surgical]] treatment-10% [[mortality]] rate
*Medical treatment- 30% [[mortality]] rate
 
==History and Symptoms==
67% of patients with [[aortic]] dissection present with [[acute]] [[symptom]]s (<2 weeks), and 33% with [[chronic]] [[symptom]]s (>= 2 weeks). 74% of patients who survive the initial tear typically present with the sudden onset of severe tearing pain.  
67% of patients with [[aortic]] dissection present with [[acute]] [[symptom]]s (<2 weeks), and 33% with [[chronic]] [[symptom]]s (>= 2 weeks). 74% of patients who survive the initial tear typically present with the sudden onset of severe tearing pain.  


===Pain===
===Physical Examination===
====Chest Pain====
[[Aortic dissection]] is commonly associated with varying blood pressure (pseudohypotension or [[hypertension]] or [[hypotension]]), [[wide pulse pressure]] (if the [[aortic root]] is involved causing [[aortic insufficiency]]), [[tachycardia]], [[pulsus paradoxus]], [[swollen face]] due to [[superior vena cava]] compression ([[superior vena cava syndrome]]). In proximal dissections involving [[aortic root]], [[aortic insufficiency]] is a [[complication]], and on physical examination an early [[diastolic]] decrescendo [[murmur]], which is best heard in the right second [[intercostal space]] is noted.
92% of patients with [[anterior]] [[chest pain]] as their major source of [[pain]] have either type I or type II dissections, and only 8% have type III. In 17% patients, the [[pain]] migrates as dissection extends down the [[aorta]].
===Laboratory Findings===
 
====Neck, Throat, and Jaw Pain====
Neck, throat, jaw, and [[unilateral]] face [[pain]] are also seen more commonly in those with type I or type II dissection.
 
====Back Pain====
52% of patients with type III dissection have the majority of their [[pain]] in the back, and 67% of these patients have some degree of back [[pain]].
 
====Pleuritic Pain====
[[Pleuritic pain]] suggests acute [[pericarditis]] associated with [[hemorrhage]] into the [[pericardial sac]].
 
====Painless Dissection====
Up to 15 – 55 % of patients can have [[pain]]less dissection. Dissection should therefore be included in the differential in patients with unexplained [[syncope]], [[stroke]] or [[congestive heart failure|congestive heart failure (CHF)]].
 
===Infrequent Symptoms===
* [[Abdominal pain]] due to [[mesenteric ischemia]]
* [[Cardiac arrest]] occurs in 4% of patients
* [[Claudication]] due to [[iliac artery]] occlusion
* [[Congestive heart failure]] may be observed due to [[aortic root]] dilatation leading to [[aortic insufficiency]]
*[[Dysphagia]] due to compression of the [[esophagus]]
*[[Hemoptysis]] due to compression of and erosion into the [[bronchus]]
*[[Horner syndrome]] due to compression of the [[superior cervical ganglia]]
* [[Oliguria]]/ [[Anuria]] due to involvement of the [[renal arteries]] causing pre-[[renal]] [[azotemia]].<ref>Saner, H.E., et al., Aortic dissection presenting as Pericarditis. Chest, 1987. 91(1): p. 71-4. PMID 3792088</ref> <ref>Rosman, H.S., et al., Quality of history taking in patients with aortic dissection. Chest, 1998. 114(3): p. 793-5. PMID 9743168</ref> <ref>Hagan, P.G., et al., The International Registry of Acute Aortic Dissection (IRAD): new insights into an old disease. JAMA, 2000. 283(7): p. 897-903. PMID 10685714</ref> <ref>von Kodolitsch, Y., A.G. Schwartz, and C.A. Nienaber, Clinical prediction of acute aortic dissection. Arch Intern Med, 2000. 160(19): p. 2977-82. PMID 11041906</ref>
* [[Paraplegia]], [[paralysis]] from involvement of one of the [[cerebral artery|cerebral]] or [[spinal cord|spinal]] [[artery|arteries]]
*[[Stridor]] and [[wheezing]] due to compression of the airway
*[[Swelling]] of the neck and face due to compression of the [[superior vena cava]] or [[Superior vena cava syndrome]]
* [[Syncope]] may occur and in 50% of cases, the [[etiology]] of the [[syncope]] is [[hemorrhage]] into the [[pericardial sac]] causing [[pericardial tamponade]]
* [[Upper gastrointestinal bleed|Upper gastrointestinal (UGI) bleed]]
*[[Vocal cord paralysis]] and [[hoarseness]] (compression of the [[recurrent laryngeal nerve]])
 
==Physical Examination==
===Blood Pressure===
====Blood Pressure Discrepancy====
''Pseudohypotension'' (falsely low [[blood pressure]] measurement) may occur due to involvement of the [[brachiocephalic artery]] (supplying the right arm) or the [[left subclavian artery]] (supplying the left arm).
==== Hypertension====
While many patients with an [[aortic]] dissection have a history of [[arterial hypertension|hypertension]], the [[blood pressure]] is quite variable among patients with [[acute]] [[aortic]] dissection, and tends to be higher in individuals with a [[distal]] dissection. In individuals with a [[proximal]] [[aortic]] dissection, 36% present with [[arterial hypertension|hypertension]], while 25% present with [[hypotension]]. In those that present with [[distal]] [[aortic]] dissections, 70% present with [[hypertension]] while 4% present with [[hypotension]].
==== Hypotension====
Severe [[hypotension]] at presentation is a grave [[prognosis|prognostic]] indicator. It is usually associated with [[pericardial tamponade]], severe [[aortic insufficiency]], or [[rupture of the aorta]]. Accurate measurement of the [[blood pressure]] is important.
 
===Pulse===
*[[Tachycardia]] may be present due to [[pain]], [[anxiety]], [[aortic rupture]]  with [[massive bleeding]], [[pericardial tamponade]], [[aortic insufficiency]] with [[acute]] [[pulmonary edema]] and [[hypoxemia]].
*A [[wide pulse pressure]] may be present if [[acute]] [[aortic insufficiency]] develops.
* [[Pulsus paradoxus]] (a drop of > 10 mmHg in [[artery|arterial]] [[blood pressure]] on [[inspiration]]) may be present of [[pericardial tamponade]] develops.
 
===General===
The patient may be [[hoarse]] due to  compression of the left [[recurrent laryngeal nerve]]
 
===Head, Eyes, Ears, Nose, Throat===
*[[Swelling]] of the neck and face may be present due to compression of the [[superior vena cava]] or [[Superior vena cava syndrome]]
*[[Horner syndrome]] may be present due to compression of the [[superior cervical ganglia]]
 
=== Heart ===
====Aortic Insufficiency====
[[Aortic insufficiency]] occurs in 1/2 to 2/3 of [[ascending aorta|ascending aortic]] dissections, and the [[heart sounds|murmur]] of [[aortic insufficiency]] is audible in about 32% of [[proximal]] dissections. The intensity (loudness) of the [[murmur]] is dependent on the [[blood pressure]] and may be inaudible in the event of [[hypotension]]. [[Aortic insufficiency]] is more commonly associated with type I or type II dissection. The [[murmur]] of [[aortic insufficiency]] ([[AI]]) due to [[aortic]] dissection is best heard at the right 2nd [[intercostal space]] (ICS), as compared with the lower left [[sternal]] border for [[AI]] due to primary [[aortic]] [[valvular disease]].
 
====Cardiac Tamponade====
* [[Beck's triad]] may be present:<ref>Gwinnutt, C., Driscoll, P. (Eds) (2003) (2nd Ed.) Trauma Resuscitation: The Team Approach. Oxford: BIOS Scientific Publishers Ltd. ISBN 978-1859960097 </ref>
** [[Hypotension]] (due to decreased [[stroke volume]])
** [[Jugular venous distension]] (due to impaired [[venous return]] to the heart)
** Muffled [[heart sounds]] (due to fluid inside the [[pericardium]]) <ref>Dolan, B., Holt, L. (2000). Accident & Emergency: Theory into practice. London: Bailliere Tindall ISBN 978-0702022395</ref>
* Distension of [[vein]]s in the forehead and [[scalp]]
* [[Altered mental state|Altered sensorium]] (decreasing [[Glasgow coma scale]])
* [[Peripheral edema]]
In addition to the [[Beck's triad]] and [[pulsus paradoxus]] the following can be found on [[cardiovascular]] examination:
* [[Pericardial rub]]
* Clicks - As [[ventricular]] volume shrinks disproportionately, there may be psuedoprolapse/true prolapse of [[mitral]] and/or [[tricuspid valve|tricuspid valvular]] structures that result in clicks.
* [[Kussmaul's sign]] - Decrease in [[jugular venous pressure]] with [[inspiration]] is uncommon.
 
=== Lungs ===
*[[Rales]] may be present due to [[cardiogenic pulmonary edema]] which may result from [[acute]] [[aortic regurgitation]].
*[[Hemothorax]] and / or [[pleural effusion]] may cause dullness to [[percussion]].
*[[Stridor]] and [[wheezing]] may be present due to compression of the airway
*[[Hemoptysis]] may be present due to compression of and erosion into the [[bronchus]]
 
=== Extremities ===
Diminution or absence of [[pulse]]s is found in up to 40% of patients, and occurs due to occlusion of a major [[aortic]] branch. For this reason it is critical to assess the [[pulse]] and [[blood pressure]] in both arms.  The [[iliac arteries]] may be affected as well.
 
=== Neurologic ===
* [[Neurologic]] deficits such as [[coma]], [[altered mental status]], [[Ddx:Cerebrovascular Accident|Cerebrovascular accident]] (CVA) and [[vagal episodes]] are seen in up to 20%.
*There can also be focal [[neurologic]] signs due to occlusion of a [[Anterior spinal artery|spinal artery]]. This condition is known as [[Anterior spinal artery syndrome]] or [[Anterior spinal artery syndrome|"Beck's syndrome"]].
 
==Laboratory Findings==
Routine blood work is usually not helpful and should not delay definitive [[diagnosis|diagnostic studies]] such as a [[CT]] scan and treatment. [[Hemolysis]] can be present as a result of blood in the [[false lumen]]. The presence of an elevated [[CK MB]] may indicate the presence of concomitant [[acute myocardial infarction]] (often a [[right coronary artery]] occlusion due to occlusion of the [[ostium]] of the [[RCA]] by the dissection). [[Hematuria]] may be present and may indicate the presence of [[renal infarction]].
Routine blood work is usually not helpful and should not delay definitive [[diagnosis|diagnostic studies]] such as a [[CT]] scan and treatment. [[Hemolysis]] can be present as a result of blood in the [[false lumen]]. The presence of an elevated [[CK MB]] may indicate the presence of concomitant [[acute myocardial infarction]] (often a [[right coronary artery]] occlusion due to occlusion of the [[ostium]] of the [[RCA]] by the dissection). [[Hematuria]] may be present and may indicate the presence of [[renal infarction]].
 
===Electrocardiogram===
==Electrocardiogram==
[[ST elevation myocardial infarction]] ([[MI]]) due to occlusion by the dissection of the [[coronary artery]] at its [[ostium]] may be present. The [[right coronary artery]] tends to be involved more frequently than the [[left coronary artery]]. [[Electrical alternans]] may be present in the setting of a [[pericardial effusion]] should the dissection have extended into the [[pericardium]].
[[ST elevation myocardial infarction]] ([[MI]]) due to occlusion by the dissection of the [[coronary artery]] at its [[ostium]] may be present. The [[right coronary artery]] tends to be involved more frequently than the [[left coronary artery]]. [[Electrical alternans]] may be present in the setting of a [[pericardial effusion]] should the dissection have extended into the [[pericardium]].
 
===Imaging in Acute aortic dissection===
==Chest X-ray==
There are a wide variety of imaging studies that can be used to [[diagnose]] [[aortic]] dissection, but in general, [[Transesophageal echocardiography (TEE)|transesophageal imaging]] is the imaging modality of choice in the [[acute]]ly ill patient and [[MRI]] is the imaging modality of choice in the assessment of longstanding [[aortic]] disease in a patient who has [[chronic]] [[chest pain]] who is [[hemodynamic]]ally stable or for the evaluation of a [[chronic]] dissection.
===Chest X-ray===
An increased [[aortic]] diameter is the most common finding on chest [[X ray]], and is observed in up to 84% of patients.  A [[widened mediastinum]] is the next most common finding, and is observed in 15-20% of patients. The chest X-Ray is normal in 17% of patients. A [[pleural effusion]] ([[hemothorax]]) in the absence of [[congestive heart failure]] can be another sign of [[aortic]] dissection.
An increased [[aortic]] diameter is the most common finding on chest [[X ray]], and is observed in up to 84% of patients.  A [[widened mediastinum]] is the next most common finding, and is observed in 15-20% of patients. The chest X-Ray is normal in 17% of patients. A [[pleural effusion]] ([[hemothorax]]) in the absence of [[congestive heart failure]] can be another sign of [[aortic]] dissection.
 
===CT===
==A General Approach to Imaging to Diagnose Aortic Dissection==
A [[CT scan]] can be used to [[diagnosis|diagnose]] [[aortic]] dissection if neither a [[TEE]] nor [[MRI]] is available in a timely fashion, or if there is a contraindication to their performance. An example would be after hours in an emergency room setting. If the results of the [[CT]] scan are non-[[diagnostic]], then [[TEE]] or [[MRI]] should be performed to confirm the [[diagnosis]].
There are a wide variety of imaging studies that can be used to [[diagnose]] [[aortic]] dissection, but in general, [[Transesophageal echocardiography (TEE)|transesophageal imaging]] is the imaging modality of choice in the [[acute]]ly ill patient and [[MRI]] is the imaging modality of choice in the assessment of longstanding [[aortic]] disease in a patient who has [[chronic]] [[chest pain]] who is [[hemodynamic]]ally stable or for the evaluation of a [[chronic]] dissection.
===MRI===
 
[[MRI]] is the imaging modality of choice in the assessment of longstanding [[aortic]] disease in a patient who has [[chronic]] [[chest pain]] who is [[hemodynamic]]ally stable or for the evaluation of a [[chronic]] dissection.
===Use of Transesophageal Echo Imaging in the Acute Setting===
===Echocardiography===
In the management of the [[acute]] patient with suspected [[aortic]] dissection, a [[Transesophageal echocardiography (TEE)|transesophageal echo]] performed acutely in the emergency room is the preferred approach. If the patient is [[hemodynamic]]ally unstable, then a [[Transesophageal echocardiography (TEE)|transesophageal echo]] can be performed in the operating room as the patient after the patient has been induced and is being prepared for [[surgery]].
In the management of the [[acute]] patient with suspected [[aortic]] dissection, a [[TEE|transesophageal echo]] performed [[acute]]ly in the emergency room is the preferred approach. If the patient is [[hemodynamic]]ally unstable, then a [[TEE|transesophageal echo]] can be performed in the operating room as the patient after the patient has been induced and is being prepared for [[surgery]].
 
===Aortography===
===Use of MRI Imaging in the Absence of Acute Disease===
[[MRI]] is the imaging modality of choice in the assessment of
*A patient who has [[chronic]] [[chest pain]] who is [[hemodynamic]]ally stable
*A [[chronic]] dissection
 
===Use of CT Scanning===
A [[CT]] scan can be used if neither a [[Transesophageal echocardiography (TEE)|TEE]] nor [[MRI]] is available in a timely fashion, or if there is a contraindication to their performance. An example would be after hours in an emergency room setting. If the results of the [[CT]] scan are non-diagnostic, they [[Transesophageal echocardiography (TEE)|TEE]] or [[MRI]] should be performed to confirm the diagnosis.
 
===Use of Aortography===
[[Aortography]] is rarely used in the modern era. It can be used of the other imaging modalities are not available or are inconclusive.
[[Aortography]] is rarely used in the modern era. It can be used of the other imaging modalities are not available or are inconclusive.
 
===Coronary Angiography===
===Use of Coronary Angiography===
Pre-operative [[angiography]] has not been associated with improved outcomes in [[retrospective]] analyses.
Pre-operative [[angiography]] has not been associated with improved outcomes in retrospective analyses. It is reasonable to perform [[coronary angiography]] in the following scenarios:
*Age over 60 years
*Presence of [[CAD risk factors]]
*History of prior [[myocardial infarction]]
 
==Medical Therapy==
==Medical Therapy==
Type A dissections of the [[proximal]] [[aorta]] are generally managed with operative repair whereas Type B dissections of the [[descending aorta]] are generally managed medically. Even patients who are undergoing operative repair require optimal medical management. The two goals in the medical management of [[aortic]] dissection are to reduce [[blood pressure]] and to reduce the oscillatory shear on the wall of the aorta (the shear-force dP/dt or force of ejection of blood from the [[left ventricle]]). The target [[blood pressure]] should be a [[mean arterial pressure|mean arterial pressure (MAP)]] of 60 to 75 mmHg.
Type A dissections of the [[proximal]] [[aorta]] are generally managed with operative repair whereas Type B dissections of the [[descending aorta]] are generally managed medically. Even patients who are undergoing operative repair require optimal medical management. The two goals in the medical management of [[aortic]] dissection are to reduce [[blood pressure]] and to reduce the oscillatory shear on the wall of the aorta (the shear-force dP/dt or force of ejection of blood from the [[left ventricle]]). The target [[blood pressure]] should be a [[mean arterial pressure|mean arterial pressure (MAP)]] of 60 to 75 mmHg.

Revision as of 21:09, 25 January 2013

Aortic dissection Microchapters

Home

Patient Information

Overview

Historical Perspective

Classification

Pathophysiology

Causes

Differentiating Aortic dissection from other Diseases

Epidemiology and Demographics

Risk Factors

Screening

Natural History, Complications and Prognosis

Diagnosis

Diagnostic Study of Choice

History and Symptoms

Physical Examination

Laboratory Findings

Electrocardiogram

X-ray

Echocardiography and Ultrasound

CT scan

MRI

Other Imaging Findings

Other Diagnostic Studies

Treatment

Medical Therapy

Surgery

Primary Prevention

Secondary Prevention

Special Scenarios

Management during Pregnancy

Case Studies

Case #1


Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Cafer Zorkun, M.D., Ph.D. [2]

Overview

Aortic dissection is a tear in the wall of the aorta that causes blood to flow between the layers of the wall of the aorta and force the layers apart. Aortic dissection is a medical emergency and can quickly lead to death, even with optimal treatment. If the dissection tears the aorta completely open (through all three layers) massive and rapid blood loss occurs. Aortic dissections resulting in rupture have a 90% mortality rate even if intervention is timely.

Acute aortic dissection is the most common fatal condition that involves the aorta. The mortality rate has been estimated to be as high as 1% per hour during the first 48 hours. Because of the diverse clinical manifestations of aortic dissection, one needs to maintain a high index of suspicion in patients with not just chest pain, but also those with stroke, congestive heart failure, hoarseness, hemoptysis, claudication, superior vena cava (SVC) syndrome, or upper airway obstruction. Despite the fact that a noninvasive diagnosis can be made in up to 90% of cases, the correct antemortem diagnosis is made less than 50% of the time. Recognition of the condition and vigorous pre-operative management are critical to survival.

Historical Perspective

DeBakey and Cooley reported the first successful operation for resection and graft replacement of the ascending aorta using cardiopulmonary bypass in 1956.

Classification

Several different classification systems have been used to describe aortic dissections. The systems commonly in use are either based on either the anatomy of the dissection (proximal, distal) or the duration of onset of symptoms (acute, chronic) prior to presentation.

Pathophysiology

Aortic dissection begins as a tear in the aortic wall in > 95% of patients. The tear is usually transverse, extends through the intima and halfway through the media and involves ~50% of the aortic circumference. Two thirds of dissections originate in the ascending aorta, and 20% are in the proximal descending aorta.

Causes

Age related changes due to atherosclerosis and hypertension are associated with spontaneous dissection, while blunt trauma injury and sudden deceleration in a motor vehicle accident is a major cause of aortic dissection.

Differentiating Aortic Dissection from other Diseases

Aortic dissection is a life threatening entity that must be distinguished from other life threatening entities such as cardiac tamponade, cardiogenic shock, myocardial infarction, and pulmonary embolism. An aortic aneurysm is not synonymous with aortic dissection. Aneurysms are defined as a localized permanent dilation of the aorta to a diameter > 50% of normal.

Epidemiology and Demographics

There are approximately 2,000 cases of aortic dissection in the US per year, and aortic dissection accounts for 3-4% of sudden deaths. The peak incidence is in the sixth and seventh decades, and males predominate 2:1.

Risk Factors

Aging, atherosclerosis, diabetes, hypertension and trauma are common risk factors for aortic dissection. Uncommon risk factors include bicuspid aortic valve, cocaine, coarctation of the aorta, cystic medial necrosis, Ehlers-Danlos syndrome, giant cell arteritis, heart surgery, Marfan’s syndrome, Pseudoxanthoma elasticum, Turner's syndrome, tertiary syphilis and the third trimester of pregnancy.

Natural History, Complications and Prognosis

Aortic dissection carries a very poor prognosis. 90% of patients who are untreated will be dead at one year. Type A dissection is associated with a worse prognosis than type B dissection. Aortic dissection can be complicated by extension to the coronary arteries resulting in myocardial infarction, involvement of the aortic arch to cause stroke, dilation of the route to cause aortic insufficiency, extension into the pericardium to cause pericardial tamponade, and heart failure, and aortic rupture.

Diagnosis

History and Symptoms

67% of patients with aortic dissection present with acute symptoms (<2 weeks), and 33% with chronic symptoms (>= 2 weeks). 74% of patients who survive the initial tear typically present with the sudden onset of severe tearing pain.

Physical Examination

Aortic dissection is commonly associated with varying blood pressure (pseudohypotension or hypertension or hypotension), wide pulse pressure (if the aortic root is involved causing aortic insufficiency), tachycardia, pulsus paradoxus, swollen face due to superior vena cava compression (superior vena cava syndrome). In proximal dissections involving aortic root, aortic insufficiency is a complication, and on physical examination an early diastolic decrescendo murmur, which is best heard in the right second intercostal space is noted.

Laboratory Findings

Routine blood work is usually not helpful and should not delay definitive diagnostic studies such as a CT scan and treatment. Hemolysis can be present as a result of blood in the false lumen. The presence of an elevated CK MB may indicate the presence of concomitant acute myocardial infarction (often a right coronary artery occlusion due to occlusion of the ostium of the RCA by the dissection). Hematuria may be present and may indicate the presence of renal infarction.

Electrocardiogram

ST elevation myocardial infarction (MI) due to occlusion by the dissection of the coronary artery at its ostium may be present. The right coronary artery tends to be involved more frequently than the left coronary artery. Electrical alternans may be present in the setting of a pericardial effusion should the dissection have extended into the pericardium.

Imaging in Acute aortic dissection

There are a wide variety of imaging studies that can be used to diagnose aortic dissection, but in general, transesophageal imaging is the imaging modality of choice in the acutely ill patient and MRI is the imaging modality of choice in the assessment of longstanding aortic disease in a patient who has chronic chest pain who is hemodynamically stable or for the evaluation of a chronic dissection.

Chest X-ray

An increased aortic diameter is the most common finding on chest X ray, and is observed in up to 84% of patients. A widened mediastinum is the next most common finding, and is observed in 15-20% of patients. The chest X-Ray is normal in 17% of patients. A pleural effusion (hemothorax) in the absence of congestive heart failure can be another sign of aortic dissection.

CT

A CT scan can be used to diagnose aortic dissection if neither a TEE nor MRI is available in a timely fashion, or if there is a contraindication to their performance. An example would be after hours in an emergency room setting. If the results of the CT scan are non-diagnostic, then TEE or MRI should be performed to confirm the diagnosis.

MRI

MRI is the imaging modality of choice in the assessment of longstanding aortic disease in a patient who has chronic chest pain who is hemodynamically stable or for the evaluation of a chronic dissection.

Echocardiography

In the management of the acute patient with suspected aortic dissection, a transesophageal echo performed acutely in the emergency room is the preferred approach. If the patient is hemodynamically unstable, then a transesophageal echo can be performed in the operating room as the patient after the patient has been induced and is being prepared for surgery.

Aortography

Aortography is rarely used in the modern era. It can be used of the other imaging modalities are not available or are inconclusive.

Coronary Angiography

Pre-operative angiography has not been associated with improved outcomes in retrospective analyses.

Medical Therapy

Type A dissections of the proximal aorta are generally managed with operative repair whereas Type B dissections of the descending aorta are generally managed medically. Even patients who are undergoing operative repair require optimal medical management. The two goals in the medical management of aortic dissection are to reduce blood pressure and to reduce the oscillatory shear on the wall of the aorta (the shear-force dP/dt or force of ejection of blood from the left ventricle). The target blood pressure should be a mean arterial pressure (MAP) of 60 to 75 mmHg.

Step 1: Urgent Surgical Consultation

  1. Simultaneous with the initiation of medical therapy as described below, urgent surgical consultation should be required regarding the potential need for operative repair of the dissection. Type A dissections of the proximal aorta are generally managed with operative repair whereas Type B dissections of the descending aorta are generally managed medically. Even patients who are undergoing operative repair require optimal medical management as described in the steps below.

Step 2: Rate Control

  1. The initial step in the medical management of the patient with aortic dissection is rate control. Rate control reduces oscillatory sheer stress as well as blood pressure. Rate control should be accomplished before vasodilators are administered in so far as vasodilators can increase oscillatory sheer stress.
  2. All patients should have an arterial line in the arm with the higher BP for accurate monitoring.
  3. Intravenous beta blockers can be administered and titrated to a heart rate of 60 bpm or less. The systolic blood pressure is kept at the lowest level that maintains adequate perfusion. Labetalol is an ideal agent in so far as it has both alpha and beta blocking properties. Initial treatment usually involves either labetalol (a 20 mg bolus followed by 20-80mg every 10 minutes to a total dose of 300 mg, or as an infusion of 0.5 to 2 mg/min) or Propranolol (1 to 10 mg load followed by 3mg/hr) with the goal being a heart rate of 60 beats per minutes. Lopressor can also be administered.
  4. If there is an absolute contraindication to the administration of beta blockers than a nondihydropyridine calcium channel–blocking can be administered as an alternative for rate control. The calcium channel blockers typically used are verapamil and diltiazem, because of their combined vasodilator and negative inotropic effects.
  5. If aortic insufficiency is present, then beta blocker administration should be undertaken carefully as prolonging the diastolic filling period may increase the magnitude of aortic regurgitation.
  6. Pain control with morphine is important in so far as it reduces sympathetic tone, heart rate and blood pressure.

Step 3: Blood Pressure Control

  1. Vasodilator administration should only be undertaken after the heart rate is controlled. If the heart rate is not controlled, the administration of vasodilators may cause reflex tachycardia, and cause further expansion of the dissection.
  2. If the systolic blood pressure remains above 120 mm Hg, then an angiotensin-converting enzyme inhibitor should be administered to further reduce the blood pressure. If this is ineffective, then the administration of parenteral vasodilators should be considered.
  3. If the heart rate is controlled, and the systolic blood pressure (SBP) is > 100 mmHg with adequate mentation and urine output, Sodium nitroprusside can be administered at a dose of 0.25 – 0.5 ug/kg/min. Nitroprusside should never be administered prior to beta blockade, as the hypotension can result in a reflex tachycardia.
  4. The target blood pressure should be a mean arterial pressure (MAP) of 60 to 75 mmHg.
  5. If the individual has refractory hypertension (persistent hypertension on the maximum doses of three different classes of antihypertensive agents), involvement of the renal arteries in the aortic dissection plane should be considered.

Step 4: Operative Repair Versus Medical Therapy

  1. Acute thoracic aortic dissection of the proximal ascending aorta (Type A dissections) should be urgently evaluated for emergent surgical repair given the increased risk of associated morbid/ mortal complications such as aortic rupture.
  2. Acute thoracic aortic dissection of the descending aorta (Type B dissection) should be managed medically unless and of the following morbid/ mortal complications develop:
  • For patients with DeBakey III or Daily B dissections, medical therapy offers an > 80% survival rate.

Step 5: Chronic Therapy

  1. In order to prevent recurrence and improve the patient's long term prognosis, smoking cessation, aggressive blood pressure control, and aggressive lipid- lowering therapy are essential. The relative risk of late rupture of an aortic aneurysm is 10 times higher in individuals who have uncontrolled hypertension, compared to individuals with a systolic blood pressure below 130 mmHg.

Surgery

Any dissection that involves the ascending aorta is considered a surgical emergency, and urgent surgical consultation is recommended. There is a 90% 3-month mortality among patients with a proximal aortic dissection who do not undergo surgery. These patients can rapidly develop acute aortic insufficiency (AI), tamponade or myocardial infarction (MI).

Contraindications to the Operative Repair of a Type A Dissection

Even acute MI in the setting of dissection is not a surgical contraindication. Acute hemorrhagic stroke is, however, a relative contraindication, due to the necessity of intraoperative heparinization.

Surgical Indications for Operative Repair of a Type B Dissection

Dissections involving only the descending aorta can generally be managed medically, but indications for surgery include the following:

Surgical Complications Following Repair of a Type B Dissection

Surgical Risk Factors

Risk factors associated with increased surgical mortality include the following:

Surgical Procedure

Surgical therapy involves excision of the intimal tear, obliteration of the proximal entry site into the false lumen, and reconstitution of the aorta with placement of a synthetic graft. AI can be corrected by resuspension of the native valve, or by aortic valve replacement (AVR).

References

Template:WH Template:WS