Aortic Dissection

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Aortic Dissection

  1. 1. Aortic Dissection Jason S. Finkelstein, M.D. Cardiology Fellow Tulane University 8/11/03
  2. 2. Overview <ul><li>Incidence of aortic dissection is at least 2000 new cases per year </li></ul><ul><li>Peak incidence is in the sixth to seventh decade </li></ul><ul><li>Men are affected twice as commonly as women </li></ul><ul><li>Mortality in the first 48 hours is 1% per hour </li></ul><ul><ul><li>Early diagnosis is essential </li></ul></ul>
  3. 3. Pathophysiology <ul><li>The chief predisposing factor is degeneration of collagen and elastin in the aortic intima media </li></ul><ul><li>Blood passes through the tear into the aortic media, separating the media from the intima and creating a false lumen </li></ul><ul><li>Dissection can occur both distal and proximal to the tear </li></ul>
  4. 4. Classification <ul><li>Debakey system </li></ul><ul><ul><li>Type I </li></ul></ul><ul><ul><ul><li>Originates in the ascending aorta, propagates to the aortic arch and beyond it distally </li></ul></ul></ul><ul><ul><li>Type II </li></ul></ul><ul><ul><ul><li>Confined to the ascending aorta </li></ul></ul></ul><ul><ul><li>Type III </li></ul></ul><ul><ul><ul><li>Confined to the descending aorta, and extends distally, or rarely retrograde into the aortic arch </li></ul></ul></ul>
  5. 5. Classification <ul><li>The Stanford system </li></ul><ul><ul><li>Type A </li></ul></ul><ul><ul><ul><li>All dissections involving the ascending aorta </li></ul></ul></ul><ul><ul><li>Type B </li></ul></ul><ul><ul><ul><li>All other dissections regardless of the site of the primary intimal tear </li></ul></ul></ul><ul><ul><li>Ascending aortic dissections are twice as common as descending </li></ul></ul>
  6. 7. Predisposing factors <ul><li>Age, 60-80 yrs old </li></ul><ul><li>Long standing history of hypertension </li></ul><ul><ul><li>80% of cases have co-existing HTN </li></ul></ul><ul><li>Takayasu’s arteritis </li></ul><ul><li>Giant cell arteritis </li></ul><ul><li>Syphilis </li></ul><ul><li>Collagen disorders </li></ul><ul><ul><li>Marfan syndrome (6-9% of aortic dissections) </li></ul></ul><ul><ul><li>Ehlers-Danlos syndrome </li></ul></ul>
  7. 8. Other Risk Factors <ul><li>Congenital Cardiac Anomalies </li></ul><ul><ul><li>Bicuspid aortic valve (7-14% of cases) </li></ul></ul><ul><ul><li>Coarctation of the aorta </li></ul></ul><ul><li>Cocaine </li></ul><ul><ul><li>Abrupt HTN, due to catecholamine release </li></ul></ul><ul><li>Trauma </li></ul><ul><li>Pregnancy (50% of dissections in women <40 yrs) </li></ul><ul><li>Iatrogenic (cardiac cath, IABP, cardiac surgery, s/p valve replacement) </li></ul>
  8. 9. Clinical Symptoms <ul><li>Severe, sharp, “tearing” posterior chest pain or back pain (occurs in 74-90% of pts) </li></ul><ul><ul><li>Pain may be associated with syncope, CVA, MI, or CHF </li></ul></ul><ul><ul><li>Painless dissection relatively uncommon </li></ul></ul><ul><li>Chest pain is more common with Type A dissections </li></ul><ul><li>Back or abdominal pain is more common with Type B dissections </li></ul>
  9. 10. Physical Exam <ul><li>Pulse deficit </li></ul><ul><ul><li>Weak or absent carotid, brachial, or femoral pulses </li></ul></ul><ul><ul><li>these patients have a higher rate of mortality </li></ul></ul><ul><li>Acute Aortic Insufficiency </li></ul><ul><ul><li>Diastolic decrescendo murmur </li></ul></ul><ul><ul><li>Best heard along the right sternal border </li></ul></ul>
  10. 11. Clinical signs <ul><li>Acute MI </li></ul><ul><ul><li>RCA most commonly involved </li></ul></ul><ul><li>Cardiac tamponade </li></ul><ul><li>Pleural effusions </li></ul><ul><li>Hypertension or hypotension </li></ul><ul><li>Hemothorax </li></ul><ul><li>Variation in BP between the arms (>30mmHg) </li></ul><ul><li>Neurologic deficits </li></ul><ul><ul><li>Stroke or decreased consciousness </li></ul></ul>
  11. 12. Clinical Signs <ul><li>Involvement of the descending aorta </li></ul><ul><ul><li>Splanchnic ischemia </li></ul></ul><ul><ul><li>Renal insufficiency </li></ul></ul><ul><ul><li>Lower extremity ischemia </li></ul></ul><ul><ul><li>Spinal cord ischemia </li></ul></ul>
  12. 13. Diagnosis <ul><li>Generally suspected from the history and PE </li></ul><ul><li>In a recent study in 2000, 96% of acute dissection patients could be identified based upon a combination of three clinical features </li></ul><ul><ul><li>Immediate onset of chest pain </li></ul></ul><ul><ul><li>Mediastinal widening on CXR </li></ul></ul><ul><ul><li>A variation in pulse and/or blood pressure (>20 mmHg difference between R & L arm </li></ul></ul><ul><li>Incidence >83% when any combination of all three variables occurred </li></ul>
  13. 14. Differential Diagnosis <ul><li>Acute Coronary Syndrome </li></ul><ul><li>Pericarditis </li></ul><ul><li>Pulmonary embolus </li></ul><ul><li>Pleuritis </li></ul><ul><li>Cholecystitis </li></ul><ul><li>Perforating ulcer </li></ul>
  14. 15. Diagnostic Tests <ul><li>EKG </li></ul><ul><ul><li>Absence of EKG changes usually helps distinguish dissection from angina </li></ul></ul><ul><ul><li>Usually non-specific ST-T wave changes seen </li></ul></ul><ul><li>CXR </li></ul><ul><li>Cardiac Enzymes </li></ul>
  15. 16. Chest X-Ray <ul><li>May show widening of the aorta with ascending aorta dissections </li></ul><ul><ul><li>Present in 63 % of patients with Type A dissections </li></ul></ul>
  16. 17. Diagnostic Imaging <ul><li>Not performed until the patient is medically stable </li></ul><ul><li>Has been a dramatic shift from invasive to non-invasive diagnostic strategy </li></ul><ul><li>Spiral CT scan </li></ul><ul><li>TEE </li></ul><ul><li>MRI </li></ul><ul><li>Angiography </li></ul>
  17. 18. Imaging <ul><li>Can identify aortic dissection and other features such as: </li></ul><ul><ul><li>Involvement of the ascending aorta </li></ul></ul><ul><ul><li>Extent of dissection </li></ul></ul><ul><ul><li>Thrombus in the false lumen </li></ul></ul><ul><ul><li>Branch vessel or coronary artery involvement </li></ul></ul><ul><ul><li>Aortic insufficiency </li></ul></ul><ul><ul><li>Pericardial effusion with or without tamponade </li></ul></ul><ul><ul><li>Sites of entry and re-entry </li></ul></ul>
  18. 20. Angiography <ul><li>First definitive test for aortic dissection </li></ul><ul><li>Traditionally considered “the gold standard” </li></ul><ul><li>Involves injection of contrast media into the aorta </li></ul><ul><ul><li>Identifies the site of the dissection </li></ul></ul><ul><ul><li>Major branches of the aorta </li></ul></ul><ul><ul><li>Communication site between true & false lumen </li></ul></ul><ul><ul><li>Can detect thrombus in the false lumen </li></ul></ul><ul><li>Disadvantages </li></ul><ul><ul><li>Not very practical in critically ill patients </li></ul></ul><ul><ul><li>Nephrotoxic contrast </li></ul></ul><ul><ul><li>Risks of an invasive procedure </li></ul></ul>
  19. 22. Spiral CT <ul><li>Sensitivity 83% </li></ul><ul><li>Specificity 90 - 100% </li></ul><ul><li>Two distinct lumens with a visible intimal flap can be identified </li></ul><ul><li>Advantages </li></ul><ul><ul><li>Noninvasive </li></ul></ul><ul><ul><li>Readily available at most hospitals on an emergency basis </li></ul></ul><ul><ul><li>Can differentiate dissection from other causes of aortic widening (tumor, periaortic hematoma, fat) </li></ul></ul><ul><li>Disadvantages </li></ul><ul><ul><li>Sensitivity lower than TEE and MRI </li></ul></ul><ul><ul><li>Intimal flap is seen < 75% of cases </li></ul></ul><ul><ul><li>Nephrotoxic contrast is required </li></ul></ul><ul><ul><li>Cannot reliably detect AI, or delineate branch vessels </li></ul></ul>
  20. 26. TTE <ul><li>First used to diagnose aortic dissections in the ’70s </li></ul><ul><li>Sensitivity 59-85%, specificity 63-96% </li></ul><ul><li>Image quality limited by obesity, lung disease, and chest wall deformities </li></ul>
  21. 28. TEE <ul><li>Sensitivity 98% Specificity 95% </li></ul><ul><li>Advantages </li></ul><ul><ul><li>Close proximity of the esophagus to the thoracic aorta </li></ul></ul><ul><ul><li>Portable procedure </li></ul></ul><ul><ul><li>Yields diagnosis in < 5 minutes </li></ul></ul><ul><ul><li>Useful in patients too unstable for MRI </li></ul></ul><ul><ul><li>True and false lumens can be identified </li></ul></ul><ul><ul><li>Thrombosis, pericardial effusion, AI, and proximal coronary arteries can be readily visualized </li></ul></ul>
  22. 29. TEE <ul><li>Lower specificity attributed to reverberations atherosclerotic vessels or calcified aortic disease producing echo images that resemble an aortic flap </li></ul><ul><li>Disadvantages </li></ul><ul><ul><li>Contraindicated in patients with esophageal varices, tumors, or strictures </li></ul></ul><ul><ul><li>Potential complications: bradycardia, hypotension, bronchospasm </li></ul></ul>
  23. 32. MRI <ul><li>Most accurate noninvasive for evaluating the thoracic aorta </li></ul><ul><li>Sensitivity 98% </li></ul><ul><li>Specificity 98% </li></ul><ul><li>Advantages </li></ul><ul><ul><li>Safe </li></ul></ul><ul><ul><li>Can visualize the whole extent of the aorta in multiple planes </li></ul></ul><ul><ul><li>Ability to assess branch vessels, AI, and pericardial effusion </li></ul></ul><ul><ul><li>No contrast or radiation </li></ul></ul><ul><li>Disadvantages </li></ul><ul><ul><li>Not readily available on an emergency basis </li></ul></ul><ul><ul><li>Time consuming </li></ul></ul><ul><ul><li>Limited applicability in pts with pacemakers or metallic clips </li></ul></ul>
  24. 34. Conclusions <ul><li>Conventional TTE is of limited diagnostic value in assessment of the thoracic aorta </li></ul><ul><li>Both TEE and MRI have excellent sensitivity, however MRI is more specific </li></ul><ul><li>MRI is the study of choice for stable patients </li></ul><ul><li>TEE is the study of choice for unstable patients </li></ul>
  25. 35. Treatment <ul><li>Acute dissections involving the ascending aorta are considered surgical emergencies </li></ul><ul><li>Dissections confined to the descending aorta are treated medically </li></ul><ul><ul><li>Unless patient demonstrates continued hemorrhage into the pleural or retroperitoneal space </li></ul></ul>
  26. 36. Surgical Options <ul><li>Excision of the intimal tear </li></ul><ul><li>Obliteration of entry into the false lumen proximally </li></ul><ul><li>Reconstitution of the aorta with interposition of a synthetic vascular graft </li></ul>
  27. 37. Type A Dissections <ul><li>Operative mortality varies from 7-35% </li></ul><ul><li>27% post-op mortality </li></ul><ul><ul><li>Patients who died had a higher rate of in-hospital complications such as strokes, renal failure, limb ischemia, & mesenteric ischemia </li></ul></ul>
  28. 38. Poor prognostic factors <ul><li>Hypotension or shock </li></ul><ul><li>Renal failure </li></ul><ul><li>Age> 70 yrs </li></ul><ul><li>Pulse deficit </li></ul><ul><li>Prior MI </li></ul><ul><li>Underlying pulmonary disease </li></ul><ul><li>Preoperative neurologic impairment </li></ul><ul><li>Renal and/or visceral ischemia </li></ul><ul><li>Abnormal EKG, particularly ST elevation </li></ul>
  29. 39. Medical therapy <ul><li>Reduce systolic BP to 100 to 120 mmHg or the lowest level that is tolerated </li></ul><ul><li>IV Beta blockers </li></ul><ul><ul><li>Propanolol (1-10 mg load, 3mg/hr) </li></ul></ul><ul><ul><li>Labetalol (20 mg bolus, 0.5 to 2 mg/min) </li></ul></ul><ul><li>If SBP remains >100mmHg, nitroprusside should be added </li></ul><ul><ul><li>Do not use without beta blockade </li></ul></ul><ul><ul><li>Avoid hydralazine </li></ul></ul><ul><li>Surgical intervention for Type B dissections reserved for patients with a complicated course </li></ul>
  30. 40. Long Term Outcome <ul><li>Type A </li></ul><ul><ul><li>Survival at 5 yrs – 68% </li></ul></ul><ul><ul><li>Survival at 10 yrs – 52 % </li></ul></ul><ul><li>Type B </li></ul><ul><ul><li>5 yrs – 60 - 80% </li></ul></ul><ul><ul><li>10 yrs – 40 – 80% </li></ul></ul><ul><ul><li>Spontaneous healing of dissection is uncommon </li></ul></ul>
  31. 41. Long-Term Management <ul><li>Medical therapy </li></ul><ul><ul><li>Oral Beta-blockers (reduces aortic wall stress) </li></ul></ul><ul><ul><li>Keep BP < 135/80 mmHg (combination therapy) </li></ul></ul><ul><ul><li>Avoidance of strenuous physical activity </li></ul></ul><ul><li>Serial imaging </li></ul><ul><ul><li>Thoracic MR scan prior to discharge </li></ul></ul><ul><ul><li>f/u scans at 3, 6, and 12 months </li></ul></ul><ul><ul><li>Subsequent screening studies done every 1-2 yrs if no evidence of progression </li></ul></ul>

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