Handout-Aortic Disease

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1 Aortic Disease Page 1 Handout-Aortic Disease November :00 PM Aortic Disease Sean Wilde - December 2011 Definitions (from medscape.com and uptodate.com) Aneurysms: An aneurysm is a segmental, full-thickness dilation of a blood vessel >150 percent of its normal diameter. Thoracic Aortic Aneurysm (TAA): Dilation of the aorta involving all three wall layers equaling or exceeding twice the normal diameter. Etiologies of true tho racic aortic aneurysms include atherosclerosis, infection (mycotic aneurysms), and cystic medial necrosis (annuloaortic ectasia). The risk of rupture or dissection increases with increasing aneurysm size. Abdominal Aortic Aneurysm (AAA): An abdominal aortic aneurysm (AAA) is considered to be present when the minimum anteroposterior diameter of the aorta (at som e point between the diaphragm and aortic bifurcation) reaches 3.0 cm. Risk factors for AAA include advancing age, family histor y (particularly for first-degree relatives), male gender, and tobacco use. The risk of rupture or leak increases with increasing aneurysm size. Pseudoaneurysm (false aneurysms): Represent saccular dilations that do not contain aortic intima. Typically, such aneurysms are associated with blunt chest tra uma or penetrating atherosclerotic ulcers or, less commonly, with infection or cardiovascular surgery. Acute Aortic Syndromes: (non-traumatic) Thoracic Aortic Dissection (TAD): A tear in the thoracic aortic intima. Blood passes into the aortic media through the tear, separating the intima from the su rrounding media and/or adventitia, and creating a false lumen. Propagation of the dissection can occur both distal and proximal to the initial tear, involving branch vessels and the aortic valve and entering the pericardial space. Aortic Intra Mural Hematoma (IMH): One of the variants of aortic dissection and is classified the same way as classic aortic dissection. It is characterized by the absence of a detectable intimal tear (although microtears may be present) and therefore the absence of continuous flow communication. Th e false channel usually originates from rupture of the vaso vasorum into the media of the aortic wall. Two mechanisms have been described: spontaneous rupture; or rupture induced by a penetrating atherosclerotic ulcer. Emergency management and referral: As in Aortic Dissection Penetrating Atherosclerotic Ulcer (PAU): Occurs when atherosclerotic plaque penetrates through the intima and internal elastic membrane of the aorta, allowing blood t o gain access to the aortic media. PAU results in IMH, and can progress to dissection, saccular aneurysm, pseudo -aneurysm, or frank aortic rupture. Emergency management and referral: As in Aortic Dissection Ruptured AAA: Rupture is a devastating complication of abdominal aortic aneurysm. An aneurysm is defined as ruptured when bleeding is prese nt outside of the wall of the aneurysm. Risk factors associated with ruptured AAA include increasing aneurysm size, rate of an eurysm expansion, female gender, smoking, and uncontrolled blood pressure. Aortocaval Fistula: An abdominal aortic aneurysm (AAA) usually ruptures into the retroperitoneal space but on rare occasions, it can erode into t he adjacent inferior vena cava (IVC), leading to aortocaval fistula. Spontaneous rupture of an AAA into the adjacent vena cava o ccurs in less than 1% of all aneurysms and in approximately 3% of ruptured aortic aneurysms. (Asian Cardiovasc Thorac Ann 2000;8: ) Suspect with chest/abdo pain and: Engorged lower leg veins Loud abdominal bruit / palpable thrill Potentially JVD, SOB

2 Aortic Disease Page 2 Treatment: Interventional radiology Aortoenteric Fistula: Direct communication between the aorta and the GI tract. Rare. Primary AEF: spontaneous fistula formation with an untreated AAA Secondary AEF: fistula in the setting of prosthetic aortic materials (early or late post AAA repair complication). Suspect in: Massive upper GI bleed Fever and back pain Known AAA or prior AAA repair (especially recent) No source of bleeding on endoscopy Sometimes seen on CT scan Treatment: Physiologic support Emergent laparotomy Stable Aneurysm Management: Thoracic: Most grow at ~0.12cm/yr 3.5-4cm, image q1 year 4.5-5cm, image q6 months Typical surgical cut-offs when dissection/rupture risk increases: Type A > 6cm Type B > 7cm Abdominal: Growth rate of cm/yr Larger/faster growing aneurysms higher rupture risk Ruptures rare in <5cm AAA Monitoring 3-4cm, ultrasound q2 years 4-5.5cm, CT or ultrasound q 6-12 months Repair generally recommended > 5.5cm Or rapidly growing Newly detected aneurysm: Some are faster growing A new small TAA or AAA should be rechecked in 3-4 months to ensure it is not a rapid expander AORTIC DISSECTION Epidemiology: 2-4 per 100,000 person years Significant, but much rarer than ACS or PE On average estimate you will see 1 AD for every 80 ACS Typically year olds Does occur in younger populations M>F 2-3X more common than ruptured AAA Mortality estimated 50% if not diagnosed Mortality increases by 1% every hour of missed diagnosis. Classification: DeBakey I-IV Rarely used, as not clinically helpful Based upon the site of origin. Type 1 originating in the ascending aorta and propagating to at least the aortic arch. Type 2 originating in and confined to the ascending aorta. Type 3 originating in the descending aorta and extending distally or proximally. Stanford- most practical Type A: any involvement of ascending aorta Risks pericardial dissection and tamponade Risks involvement of major vessels of arch

3 Aortic Disease Page 3 Highest mortality Almost always surgical management Type B: only involves descending aorta Most often treated medically Still require surgical assessment Surgical if any arterial branches compromised leading to territorial symptoms Neuro, GI, GU, etc. Risk Factors: In practice these are not always very helpful in making the diagnosis. They can alter your level of suspicion, and should at least be documented if negative. Age classically Hypertension Chronic, poorly controlled Not necessarily present acutely Psuedohypotension (in 1 or more limbs) from a dissected arterial branch possible Family history!! Known prior aortic disease, including repaired Consider in younger patients with the following risks: Pregnancy 3rd trimester highest risk Bicuspid aortic valve Connective Tissue disorders Marfans Ehlers-Danlos SLE Coarctation/congenital heart disease Turner's syndrome Cocaine or other stimulant use Mean 12 hours from last use to presentation Infectious disease Syphilis Endocarditis Making the Diagnosis: International Registry of Aortic Dissection (IRAD) Study Hagan, et al. - Largest database of patients with conformed TAD - Multiple publications of clinical/lab/imaging features of these patients - Take Home Points: *** Classic history and findings are often absent *** *** Atypical presentations are the rule *** Finding Present in % of: Type A AD Type B AD Any AD Hypertension 36% 70% 50% CP described as sudden, severe, sharp. Typically anterior Abdominal/ back 73% Pulse deficit 15% Aortic murmur 44% 12% 32% NORMAL CHXR 12% ABSENT mediastinal widening 34% Syncope 13% Abdominal Pain 22% 43% TIA/CVA symptoms 5-10% Any Neurological defs 18-30% Spinal Cord symptoms 10% PAINLESS!! 2.2% to 15%

4 Aortic Disease Page 4 Ischemia on ECG (usually inferior) 15% STEMI on ECG 1% LVH on ECG 26% Remember these values mean that in a known population of AD patients, the given percentage exhibited the finding. This descri bes prevalence of the finding in an AD population, but does not say anything about positive or negative predictive value in an undifferentiated patient. Atypical Presentations: Multiple retrospective studies and case reports suggest that in a large number of missed or misdiagnosed dissections, the phy sician ignored a reported symptom that did not fit with the working diagnosis, but which in retrospect was an important clue to the true diagnosis. The Following clues on presentation should set off your "consider aortic dissection" radar: *** The Chest Pain AND Phenomena **** Chest Pain AND Neurologic symptoms (CVA) Dysphagia, cough, hoarseness Horner's syndrome, visual changes, facial droop, slurred speech Limb paresthesia Persistent or transient Spinal Cord symptoms Lower limb weakness or paresthesias Transverse myelitis Progressive myelopathy Para/quadriplegia Anterior spinal cord syndrome Syncope AD should be on the painless syncope ddx too Abdominal Pain Lower limb pain SVC syndrome Any other unexplained symptom that could be attributable to compromise of a spinal arterial branch, or obstruction from an expanding aorta. ***Unexplained Abdominal Pain AND*** Hypotension Chest pain Cocaine use Un-well looking patient High risk features for AD ***Other*** Unexplained painless lower extremity weakness Isolated abdominal pain Syncope New onset CHF Typically have no to mild pain compared to classic AD patients An MI not responding to ACS therapy 1% of AD will look like STEMI, almost always inferior territory Most people will not see an AD masquerading as a STEMI in their career Still let it cross your mind, especially pre-thrombolytics ***Worth considering in any presentation with symptoms above AND below the diaphragm*** Investigations: Major Chest X-ray findings of AD: Widened mediastinum Not very sensitive and even less specific Intimal Calcification >10mm space between calcified intima and edge of aorta

5 Aortic Disease Page 5 Isolated left pleural effusion Other Findings: obliteration of the aortic knob depression of the left mainstem bronchus loss of the paratracheal stripe tracheal deviation Visible widening of the aorta Radiologic Criteria for dissection in plain chest radiograph: Demonstrates mediastinal widening in around 63% of patients with an aortic dissection, however this finding is nonspecific an d is seen in many normal age-matched controls. Internal displacement of aortic calcifications by 1 cm or more and disparity in size between the ascending and descending aor ta are more specific for aortic dissection, especially when they represent a new finding compared to old films. Inlet to outlet shadow with wavy margins Frequently a left pleural effusion is seen. Bulging of the aortic contour can indicate the likely site of origin of a dissection. ( EDE ultrasound Can pick up tamponade and possibly large flap in proximal type A Can't use to rule out Aortic Angiography (traditional gold standard) Sensitivity: 90-98% Specificity: 95-98% CT Chest (current practical gold standard) Sensitivity: 94% Specificity: 90% Generally required for surgical planning (in a stable patient) Transesophageal Echocardiogram (Increasingly popular) Sensitivity: 97% Specificity: 75-90% Can do at bedside in a hemodynamically unstable patient MRI Chest Sensitivity: 98% Specificity: 98% Can go straight to OR if type A dissection is seen on any modality D-dimer bottom line: Lots of evidence suggesting it is almost always elevated in AD A negative D-dimer probably means no AD (unless it is very early, or an isolated IMH) Obviously it is an extremely non-specific test Cannot currently be used as we use it in a PE rule out due to the lack of a validated low pre -test probability rule set. Will be very difficult to derive due to multitude of possible presentations In PE, D-dimer has led to an increase in imaging without an increase in number of diagnosed PE's according to some studies. Missing a small PE is much less clinically significant than missing a small, early AD. Almost all studies are cohort, retrospective or case controlled Compare known AD with other dx or healthy controls Do not represent undifferentiated ED chest pain patients (or the atypical presentation population) Cannot use them to generate a reliable negative predictive value in an ED population. If you have a rather low suspicion (alternate preferred diagnosis) and are teetering on the edge of imaging, it has been suggested that a normal CHXR and negative D-dimer may be enough to avoid CT, but no formalized decision rules exist. Am J Cardiol 2011;107: last D-dimer in AD meta-analysis (sensitivity 97%). ED Management: Key Principle: Anti-impulse therapy. Reduce the shearing stress of arterial blood flow on the intimal flap. Requires reduction of blood

6 Aortic Disease Page 6 pressure with out an increase in ventricular contractility. Beta blocker first Labetalol 20mg bolus 20-80mg q10min, max 300mg Infusion 0.5-2mg/min Propranolol 1-10mg load 3mg/hr Esmolol 500ug/kg bolus Then infusion CCB (diltiazem) in BB intolerant Then vasodilation Nitroprusside mcg/kg/min Can use ACEI Nitroglycerin not recommended (not as studied, possibly less effective) Avoid hydralazine, nifedipine Increases aortic shear wall stress Target SBP or as low as tolerated If high suspicion and patient is hypertense, start BB before going to CT scan. Patient Hypotense? Poor prognosis - needs rapid surgery Determine if shock is due to blood loss, tamponade or cardiac failure May need fluid Avoid ionotropes Some level of permissive hypotension is reasonable Type A = medical stabilization and emergency surgery Might delay OR if associated completed stroke (increased risk of hemorrhage) May do as urgent rather than emergent if >48hrs since onset and patient is stable (subacute AD). Type B = medical management and surgical consult Some benefit to repair in some cases Higher mortality with early surgery If any symptoms of disrupted organ perfusion, will need emergent surgery Key Points to reduce missed diagnosis: Consider AD in every chest pain Know the atypical presentations well AD causing stroke AD causing syncope Even if painless AD causing paralysis Spinal syndromes or limb weakness AD presenting like an MI Chest pain AND syndromes Especially with neuro symptom Complaints above and below the diaphragm Integrate all the patients complaints Don't discount inconsistent symptoms just because you think ACS, PE or GI is more likely. Consider the high risk, younger patients Pregnant Stimulants Abnormal appearing Many undiagnosed Marfan's out there Young patients without risk factors can have AD too Consider potential utility of EDE, CHXR and D-dimer in low risk patients. Key Points in charting (to keep the lawyers happy):

7 Aortic Disease Page 7 Chart absence of classic symptoms Risk factor profile (HTN, cocaine, FHx) Bilateral BP's But up to 20mmHg difference is normal (19%) Equal bilateral pulses Much more useful than BP's No aortic Insufficiency murmur Document grossly normal neuro status Non marfanoid appearance Stroke patient? Document absence of chest pain and syncope Console yourself with: The standard of care for an AD is to miss it Many in litigation are ruled "un-diagnosable." A STEMI is almost always really a STEMI Unless you have a really good reason to be suspicious, a mostly normal chest x-ray is a reasonable pre-lytics rule out. You will hurt more people than you will help by regularly delaying ACS treatment for a CT scan. AAA Risk Factors: Advanced age (>75% older then 60) Male Family history (esp sibling) Hypertension Smoking History of CAD/PVD Known Fem-Pop aneurysm Presentation: Syncope +/- back pain Vasculopath with new back pain or a CHANGE in back pain Abdo/ Flank or Back pain Possible radiation to scrotum/groin Acute, severe, constant Back of thighs or buttock pain N&V Within first 24 hours If hypotensive they have 50% survival May have unequal femoral pulses But equal does not rule out Classic pulsatile, expansile mass 5% have abdominal bruit Distal thromboemblic events Livedo reticularis Cool, dark toe with foot pulses preserved *** Ruptured AAA can present just like renal colic, including hematuria*** (and renal colic can have no hematuria 10-20% of the time) Diagnosis: EDE ultrasound Excellent specificity % Rapid, safe, no moving unstable patient Be sure to visualize entire aorta Cannot determine if leaking or not CT Scan Only if stable Call surgeon first if unstable X-ray

8 Aortic Disease Page 8 Only useful finding is eggshell sign (aorta visible beyond visible calcified vessel wall) Management: Stat call to surgeon Mortality 30-50% 2 large bore IVs Type and screen Consider getting massive transfusion available Hypertension and a slowly leaking AAA Treat pain first Hypotension Caution with fluids/blood This is a case for permissive hypotension Avoid "popping the clot" Vascular surgery literature is very clear - prefer permissive hypotension to aggressive fluid resuscitation. Supportive Care Avoid sedation/intubation if at all possible pre-or Induction may drop the sympathetic tone holding them together. Only intubate if they deteriorate enough that you don't need induction drugs With RSI and Intubation: Cardiovascular collapse often follows Cardio depressant effects of meds Relaxation of musculature releases tamponade PPV decreases venous return Reduction in sympathetic tone Trevor Langhan/Greg Samis rounds quote: Induction of anesthesia should only be performed with the patient on the OR table, fully prepped for surgery and with blood for transfusion present Large non leaking AAA as a cause of pain? Can be; usually chronic, progressive back/leg or flank pain Typically not an acute severe pain presentation - look for something else Compression of surrounding nerves, tissues and blood vessels