Aortic dissection, pathophysiology, risk, incidence, types and treatment, Moh'd Sharshir

Aortic dissection, pathophysiology, risk, incidence, types and treatment

1. Case presentation Moh’d Sharshir , Fellow Critical Care King Faisal Specialist Hospital & Research Center

2. History 55 years old gentleman, known case DM, HTN, IHD, old stroke. He was transferred from another hospital on 27/11. Case of RTA with poly trauma ( head trauma, chest trauma, cardiac contusion, aortic injury, bony fractures) Referred to our hospital for endovascular aortic repair

3. examination Neurologic: On Sedation (Fentanyl and Propofol ), RASS of -4. Respiratory: Intubated, PCV( FiO2 is 50%, 20/8), O2Sat 100 %. Cardiovascular: No inotropes, HD is stable. Infectious disease: Afebrile, WBC is WNL, started on Tazo . Empirically. Gastrointestinal: Abdomen soft and lax. Endocrine: Blood Sugar = 8. Hematology: HB 86, Plt WNL. Prophylaxis: on omeprazole.

4. Laboratory

5. CXR 27/11/2015

6. CT BRAIN 27/11/2015 Conclusion: 1- Right fronto - parieto -temporal contusion with no underlying skull fracture. 2- small amount of subdural hematoma at the tentorium. 3- multiple facial bones fractures .

7. Echocardiogram on 28/11/2015 Rhythm: Sinus bradycardia. There is no comparison study available. The study was technically difficult. The left ventricle is normal in size. Ejection Fraction = 45-50%. Likely raised LV Filling pressure. Hypokinesia of inferior wall and posterior septum. The right ventricle is normal in size and function. No significant valvular abnormalities. IVC looks normal size and noncollapsible with inspiration RVSP~ 30 mmHg

8. CT CHEST & abdomen & PELVIC 27/11/2015 Conclusion : 1. There is small defect with contrast filled out pouching in proximal part of descending thoracic aorta consistent with pseudoaneurysm . 2. Bilateral plural effusion with bilateral air space disease. 4. Diffuse subcutaneous emphysema.

9. Aortic dissection

10. INTRODUCTION

11. INTRODUCTION Aortic dissection is a relatively uncommon, though catastrophic illness often presenting with severe chest pain and acute hemodynamic compromise. Early and accurate diagnosis and treatment are crucial for survival.

12. PATHOPHYSIOLOGY

13. PATHOPHYSIOLOGY The primary event in aortic dissection is a tear in the aortic intima. Degeneration of the aortic media, or cystic medial necrosis.

14. PATHOPHYSIOLOGY Blood passes into the aortic media through the tear, separating the intima from the surrounding media and/or adventitia, and creating a false lumen.

15. PATHOPHYSIOLOGY It is uncertain whether the initiating event is a primary rupture of the intima with secondary dissection of the media, or hemorrhage within the media and subsequent rupture of the overlying intima.

16. PATHOPHYSIOLOGY 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. Such propagation is responsible for many of the associated clinical manifestations, including ischemia (coronary, cerebral, spinal, or visceral), aortic regurgitation, and cardiac tamponade. In addition, multiple communications may form between the true lumen and the false lumen.

17. INCIDENCE AND RISK FACTORS

18. INCIDENCE The incidence: range from 2.6 to 3.5 per 100,000 person-years. Bickerstaff LK, Pairolero PC, Hollier LH, et al. Thoracic aortic aneurysms: a population-based study. Surgery 1982; 92:1103.

19. RISK FACTORS Systemic hypertension: Most important predisposing factor. History of atherosclerosis. Preexisting aortic aneurysm. Inflammatory diseases that cause a vasculitis (Giant cell arteritis, Takayasu arteritis, Rheumatoid arthritis, Syphilitic aortitis ). Disorders of collagen ( eg , Marfan syndrome, Ehlers- Danlos syndrome, annuloaortic ectasia).

20. RISK FACTORS A bicuspid aortic valve. Aortic coarctation . Turner syndrome. Coronary artery bypass graft surgery (CABG). Previous aortic valve replacement. Cardiac catheterization with or without coronary intervention.

21. RISK FACTORS Trauma rarely causes a classic dissection, but can induce a localized tear in the region of the aortic isthmus. More commonly, chest trauma from acute deceleration (as in a motor vehicle accident) results in aortic rupture or transection. A number of theories are used to explain the mechanism of thoracic aortic injury at the isthmus. The isthmus is thought to be a transition zone between the more mobile ascending aorta and arch and the relatively fixed descending thoracic aorta which allows for stretching with rapid deceleration. The isthmus may be intrinsically weaker than the remainder of the aorta. The “osseous pinch,” theory purports that the aorta is trapped between the anterior bony structures (manubrium, first rib, medial clavicles, and sternum) and the vertebral column leading to focal rupture.

22. RISK FACTORS High-intensity weight lifting or other strenuous resistance training. Crack cocaine.

23. TYPES OF AORTIC DISSECTION

24. TYPES OF AORTIC DISSECTION The STANFORD system is more widely used. Type A : Involve the ascending aorta as, regardless of the site of the primary intimal tear. Type B : All other dissections as. The DEBAKEY system is 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. Two different anatomic systems, the DEBAKEY and STANFORD systems.

25. TYPES OF AORTIC DISSECTION Ascending aortic dissections are almost twice as common as descending dissections. The right lateral wall of the ascending aorta is the most common site of aortic dissection. In patients with an ascending aortic dissection, aortic arch involvement is seen in up to 30 percent.

26. TYPES OF AORTIC DISSECTION Isolated abdominal aortic dissection is reported sporadically and can be due to iatrogenic, spontaneous, or traumatic mechanisms. The infrarenal abdominal aorta is more commonly involved than the suprarenal aorta. A concomitant abdominal aortic aneurysm was identified in 40 percent of patients and indicated the need for repair.

27. CLINICAL MANIFESTATIONS

28. CLINICAL MANIFESTATIONS Patients with an aortic dissection typically present with severe, sharp or tearing. Posterior chest or back pain (in dissection distal to the left subclavian) or anterior chest pain (in ascending aortic dissection). The pain can radiate anywhere in the thorax or abdomen. It can occur alone or be associated with syncope, a cerebrovascular accident, myocardial infarction (MI), heart failure or other clinical symptoms or signs.

29. CLINICAL MANIFESTATIONS Chest pain typically abrupt in onset . Chest pain more common in patients with Type A dissections, while both back pain and abdominal pain more common with Type B dissections. Hagan PG, Nienaber CA, Isselbacher EM, et al. The International Registry of Acute Aortic Dissection (IRAD): new insights into an old disease. JAMA 2000; 283:897 .

30. CLINICAL MANIFESTATIONS Painless dissection has been reported, but is relatively uncommon. Patients with painless dissection were older and more often had a Type A dissection. A prior history of diabetes, aortic aneurysm, or cardiovascular surgery was more common in patients with painless dissection. Park SW, Hutchison S, Mehta RH, et al. Association of painless acute aortic dissection with increased mortality. Mayo Clin Proc 2004; 79:1252.

31. CLINICAL MANIFESTATIONS Presenting symptoms of syncope, heart failure, or stroke were seen more often in this group. In-hospital mortality was significantly higher than for patients presenting with pain. Gaul C, Dietrich W, Friedrich I, et al. Neurological symptoms in type A aortic dissections. Stroke 2007; 38:292.

32. CLINICAL MANIFESTATIONS Syncope during aortic dissection is associated with worse outcomes. Nallamothu BK, Mehta RH, Saint S, et al. Syncope in acute aortic dissection: diagnostic, prognostic, and clinical implications. Am J Med 2002; 113:468.

33. CLINICAL MANIFESTATIONS Although a history of hypertension is common, hypertension at initial presentation is more common in those with a distal (Type B) dissection.

34. CLINICAL MANIFESTATIONS The presence of impaired or absent blood flow to peripheral vessels is manifest as a pulse deficit, defined as a weak or absent carotid, brachial, or femoral pulse resulting from the intimal flap or compression by hematoma. These patients have a higher rate of in-hospital complications and mortality than those without a pulse deficit. Women are less likely to have a pulse deficit than men.

35. CLINICAL MANIFESTATIONS

36. CLINICAL MANIFESTATIONS

37. Involvement of the ascending aorta

38. Involvement of the ascending aorta Acute aortic valve regurgitation, leading to a diastolic decrescendo murmur, hypotension, or heart failure, in one-half to two-thirds of ascending dissections. Acute myocardial ischemia or myocardial infarction due to coronary occlusion. The right coronary artery is most commonly involved and, in infrequent cases, leads to complete heart block. Cardiac tamponade and sudden death due to rupture of the aorta into the pericardial space. Tamponade occurs more often in women than in men. Hemothorax and exsanguination if the dissection extends through the adventitia, with hemorrhage into the pleural space. A considerable variation (>20 mmHg) in systolic blood pressure between the arms. Neurologic deficits, including stroke or decreased consciousness due to direct extension of the dissection into the carotid arteries or diminished carotid blood flow. Alterations of consciousness are more common in women than in men. Horner syndrome if there is compression of the superior cervical sympathetic ganglion. Vocal cord paralysis and hoarseness due to compression of the left recurrent laryngeal nerve

39. Involvement of the ascending aorta Elderly; there are some important differences between elderly and younger patients with dissections involving the ascending aorta. The following differences were noted between the two groups : Marfan syndrome was not seen in any elderly patient. Elderly patients were significantly more likely to have atherosclerosis, prior aortic aneurysm, iatrogenic dissection, or intramural hematoma, and were significantly less likely to have the abrupt onset of pain. Elderly patients were significantly less likely to undergo surgery and had a higher mortality rate with either surgery or medical therapy Mehta RH, O'Gara PT, Bossone E, et al. Acute type A aortic dissection in the elderly: clinical characteristics, management, and outcomes in the current era. J Am Coll Cardiol 2002; 40:685.

40. Involvement of the descending aorta

41. Involvement of the descending aorta Chest or back pain 86 percent Abdominal pain 43 percent Abrupt onset of pain 89 percent Migrating pain 25 percent Hypertension 69 percent Hypotension/Shock 3 percent Pulse deficit 21 percent Spinal Cord Ischemia 3 percent Ischemic peripheral neuropathy 2 percent Hagan PG, nienaber CA, isselbacher EM, et al. The international registry of acute aortic dissection (IRAD): new insights into an old disease. Jama 2000; 283:897.

42. DIAGNOSIS

43. DIAGNOSIS Aortic dissection is generally suspected from the history and physical examination. Acute aortic dissections could be identified based upon some combination of the following three clinical features: Abrupt onset of thoracic or abdominal pain with a sharp, tearing and/or ripping character. Mediastinal and/or aortic widening on chest radiograph. A variation in pulse (absence of a proximal extremity or carotid pulse) and/or blood pressure (>20 mmHg difference between the right and left arm). Von kodolitsch Y, schwartz AG, nienaber CA. Clinical prediction of acute aortic dissection. Arch intern med 2000; 160:2977.

44. DIAGNOSIS The incidence of a dissection related to the presence or absence of these three: All three absent: 4 percent Pain: 31 percent Presence of chest radiographic abnormalities: 39 percent Variation in pulse or blood pressure differential: ≥83 percent Any two out of three variables: 77 percent Von kodolitsch Y, schwartz AG, nienaber CA. Clinical prediction of acute aortic dissection. Arch intern med 2000; 160:2977

45. DIAGNOSIS Blood tests

46. DIAGNOSIS Blood tests D-Dimer: is one of the major fibrin degradation products and is generated from cross-linked fibrin. An elevated plasma concentration of D-Dimer indicates recent or ongoing intravascular blood coagulation. As a nonspecific indicator of intravascular coagulation, D-dimer can be elevated in many conditions.

47. DIAGNOSIS Blood tests D-dimer appears to be a useful screening tool to identify patients who do not have acute aortic dissection. A cut-off of 500 ng/mL has been widely used and levels below this value are highly predictive for excluding dissection. Suzuki T, distante A, zizza A, et al. Diagnosis of acute aortic dissection by d-dimer: the international registry of acute aortic dissection substudy on biomarkers ( irad -bio) experience. Circulation 2009; 119:2702.

48. DIAGNOSIS Blood tests A systematic review identified seven studies that used assays for plasma D-dimer to screen patients for acute aortic dissection and included a control group. For D-dimer <500 ng/mL, the pooled estimate of the sensitivity was 97 percent, specificity was 56 percent and negative predictive value was 96 percent. It was concluded that patients with a D-dimer <500 ng/mL are not likely to benefit from further aortic imaging.

49. DIAGNOSIS Blood tests Serum lactate dehydrogenase: concentration may be elevated due to hemolysis of blood in the false lumen, but this is a nonspecific finding.

50. DIAGNOSIS Blood tests Serum concentration of smooth muscle myosin heavy chain :has been evaluated in patients suspected of having an aortic dissection. The sensitivity and specificity of this assay in the first three hours were similar and possibly superior to those of TTE, conventional CT, and aortography, but were lower than those of TEE, helical CT, or MRI. Suzuki T, katoh H, watanabe M, et al. Novel biochemical diagnostic method for aortic dissection. Results of a prospective study using an immunoassay of smooth muscle myosin heavy chain. Circulation 1996; 93:1244.

51. DIAGNOSIS Electrocardiogram Electrocardiogram : Normal. Nonspecific ST and T wave changes (commonly, LVH and strain patterns associated with hypertension). Ischemic changes. Acute MI. Hagan PG, nienaber CA, isselbacher EM, et al. The international registry of acute aortic dissection (IRAD): new insights into an old disease. Jama 2000; 283:897.

52. DIAGNOSIS Imaging Imaging studies to establish the diagnosis of aortic dissection are not performed until the patient is stabilized medically. There has been a shift from an invasive (x-ray aortography) to a noninvasive diagnostic strategy for evaluating suspected thoracic aortic dissections. Recent experience suggests that CT is even more prevalent as the initial study of choice, especially due to its widespread availability in the emergency department setting. Multiplane TEE, Chest CT, and Chest MRI are thought to be superior to transthoracic echocardiography and aortography.

53. DIAGNOSIS Imaging Transthoracic echocardiography may be useful to identify proximal ascending aortic dissections, particularly with regard to coexistent aortic valve disruption/regurgitation and hemopericardium . although it is not sufficient to delineate the extent of the dissection, or any associated bleeding or complications of dissection .

54. DIAGNOSIS Imaging Chest radiograph : Widening of the aorta with aortic dissections. No abnormality on chest radiography Pleural effusion.

55. DIAGNOSIS Imaging Chest radiograph : The IRAD review of 464 patients found that : mediastinal widening was present in 63 percent with Type A dissections, while 11 percent of patients had no abnormality on chest radiography. The comparable values in patients with Type B dissections were 56 and 16 percent. Radiographic evidence of a pleural effusion was found in 19 percent of dissections; this finding is more common in women than in men (26 versus 15 percent). Because of the limited sensitivity of the chest radiograph, especially in Type B dissections, additional imaging studies are obtained in almost all patients (98 percent in data from IRAD). Hagan PG, nienaber CA, isselbacher EM, et al. The international registry of acute aortic dissection (IRAD): new insights into an old disease. Jama 2000; 283:897

56. DIAGNOSIS Imaging Aortography : invasive x-ray aortography involves the injection of iodinated contrast media into the aortic lumen, thereby permitting identification of the site of dissection, the relationship between the dissection and the major branches of the aorta, and the communication site between the true and false lumen. aortography has generally been replaced by noninvasive testing to establish the diagnosis of aortic dissection. It may also take longer to obtain in critically ill patients.

57. DIAGNOSIS Imaging Aortography : Aortography had, in a comparative review of 164 patients (82 had a dissection): Sensitivity: 88 percent . Specificity: 94 percent . Positive Predictive Values: 96 percent. Negative Predictive Values: 84 percent . Erbel R, engberding R, daniel W, et al. Echocardiography in diagnosis of aortic dissection. Lancet 1989; 1:457.

58. DIAGNOSIS Imaging CT Scan : The diagnosis of aortic dissection by CT scanning requires that, after injection of intravenous iodinated contrast, two distinct lumens with a visible intimal flap are identified.

59. DIAGNOSIS Imaging CT Scan : In two reports of 162 and 110 patients, the sensitivity of standard CT for the diagnosis of aortic dissection were 83 and 98 percent and the specificity was 87 and 100 percent, respectively. Erbel R, engberding R, daniel W, et al. Echocardiography in diagnosis of aortic dissection. Lancet 1989; 1:457.

60. DIAGNOSIS Imaging CT Scan : Advantages of CT : Availability at most hospitals, even on an emergency basis, Identification of intraluminal thrombus and pericardial effusion. Disadvantages of standard CT are that The intimal flap is seen in less than 75 percent of cases and that the site of entry is rarely identified. Potentially nephrotoxic iodinated contrast is required. There is no capability to assess for aortic insufficiency. Erbel R, engberding R, daniel W, et al. Echocardiography in diagnosis of aortic dissection. Lancet 1989; 1:457.

61. DIAGNOSIS Imaging CT scan : The accuracy of CT appears to be substantially improved with spiral (helical) CT and perhaps with multidetector ( multislice ) CT. Spiral CT may be more accurate than MRI or TEE in the detection of aortic arch vessel involvement.

62. DIAGNOSIS Imaging MRI : although less commonly used, MRI is a highly accurate noninvasive technique for evaluating the thoracic aorta in patients with suspected dissection. The presence of a double lumen with a visible intimal flap is the diagnostic criterion for aortic dissection and/or widening of the aorta with a thickened wall and thrombosis of the false lumen.

63. DIAGNOSIS Imaging MRI : In a prospective trial of 110 patients with suspected aortic dissection, the sensitivity and specificity of MRI were both 98 percent, with 85 percent sensitivity for identification of the site of entry. Nienaber CA, von kodolitsch Y, nicolas V, et al. The diagnosis of thoracic aortic dissection by noninvasive imaging procedures. N engl J med 1993; 328:1.

64. DIAGNOSIS Imaging The advantage of MRI: Safe in adequately monitored patients with aortic dissection. MR contrast agents have a more favorable safety profile than iodinated contrast agents. Ability to assess branch vessels, although it may be less sensitive than spiral CT. Assess for aortic insufficiency.

65. DIAGNOSIS Imaging The disadvantages of MRI: Inconvenience (patients are required to remain motionless with relatively limited access for more than 30 minutes). limited applicability (MRI cannot be performed in patients with claustrophobia, pacemakers, or certain types of aneurysm clips or metallic ocular/auricular implants). MRI is also not readily available on an emergency basis at many institutions. Gadolinium administration for contrast-enhanced MRI in patients with moderate to severe kidney disease (particularly dialysis patients) has been associated with the often severe syndrome of nephrogenic systemic fibrosis

66. DIAGNOSIS Imaging TTE : Has limited utility for evaluation of the thoracic aorta for dissection. The primary problem with TTE is its inability to adequately visualize the distal ascending, transverse, and descending aorta in a substantial majority of patients. The sensitivity and specificity of TTE are inferior to those with CT, MRI, and TEE. TTE is most useful for the assessment of cardiac complications of dissection, including aortic insufficiency, pericardial effusion/tamponade, and regional left ventricular systolic function.

67. DIAGNOSIS Imaging TEE : Although it requires esophageal intubation, TEE is a portable procedure, which is easily performed in the emergency department and yields a diagnosis within minutes from the start of the procedure. It may be particularly useful in patients too unstable or inappropriate ( eg , pacemaker or other contraindication) for MRI. TEE usually requires procedural sedation, which may have untoward hemodynamic effects in unstable patients.

68. DIAGNOSIS Imaging TEE : The following findings may be seen on TEE in patients with aortic dissection: Intimal dissection flaps can be identified with high spatial resolution. The use of M-mode echocardiography may improve diagnostic accuracy by demonstrating a lack of relation between movement of the intimal flap and the aortic wall. The true and false lumens can be identified. They may not be distinguishable without color doppler imaging or identification of the proximal border of the dissection.

69. DIAGNOSIS Imaging TEE : The following findings may be seen on TEE in patients with aortic dissection: Thrombosis in the false lumen, pericardial effusion, concomitant aortic regurgitation, and the proximal coronary arteries can be readily visualized. The 135º long axis view from TEE can define the severity and mechanism of aortic regurgitation that complicates acute type A dissections.

70. DIAGNOSIS Imaging

71. DIAGNOSIS CHOICE OF IMAGING STUDY Selection of a diagnostic test for suspected aortic dissection requires consideration both of the information required and of the access to and experience with the imaging modality at the institution. Thoracic MRI, thoracic CT, and multiplane TEE are the preferred methods for evaluating suspected aortic dissection, if available. The recommendations for the use of different imaging modalities in acute and chronic aortic dissection are generally in agreement with guidelines published by a task force of the European Society of Cardiology.

72. DIAGNOSIS CHOICE OF IMAGING STUDY We generally perform multiplane TEE at the bedside or in the emergency department for patients who present with acute chest pain and/or are clinically unstable. Hemodynamically unstable patients with a very strong suspicion of dissection can be emergently brought to the operating room and undergo TEE after induction of anesthesia as the chest is being prepared. Thoracic MRI is preferred in patients with chronic chest pain and in those who are hemodynamically stable, or are seen for follow-up of a chronic dissection.

73. DIAGNOSIS CHOICE OF IMAGING STUDY Chest CT scan with contrast is reserved for situations in which both TEE and MRI are unavailable or contraindicated. As such, it is often indicated as an initial screening study in patients with suspected aortic dissection, especially in the emergency department setting where TEE and MRI are less available, and especially after hours. If CT is equivocal, or further delineation of the dissection is needed, TEE or MRI is indicated. Digital subtraction aortography is used when ascending aortic dissection is strongly suspected, but noninvasive tests are unavailable or inconclusive. Coronary angiography is generally safe in stable patients, although the delay to surgical invention for ascending dissections should be minimized. Retrospective data suggest no in-hospital benefit to coronary angiography.

74. management of aortic dissection

75. GENERAL PRINCIPLES

76. GENERAL PRINCIPLES Acute dissections involving the ascending aorta are considered surgical emergencies. In contrast, dissections confined to the descending aorta are treated medically unless the patient demonstrates progressive dissection with end-organ ischemia or continued hemorrhage into the pleural or retroperitoneal space.

77. GENERAL PRINCIPLES In a review of 464 patients from the international registry of acute aortic dissection (IRAD) presenting with aortic dissection, 72 percent of those with a Type A dissection were treated surgically. Reasons for medical therapy included advanced age, comorbidity, patient refusal, intramural hematoma, or death prior to planned surgery. In contrast, only 20 percent of those with a Type B dissection underwent surgery. Hagan PG, nienaber CA, isselbacher EM, et al. The international registry of acute aortic dissection (IRAD): new insights into an old disease. Jama 2000; 283:897.

78. Hagan PG, nienaber CA, isselbacher EM, et al. The international registry of acute aortic dissection (IRAD): new insights into an old disease. Jama 2000; 283:897

79. GENERAL PRINCIPLES A similar difference in management of older patients was noted in another IRAD review of 550 patients with a type a dissection, including 32 percent who were at least 70 years [5]. Elderly patients were significantly less likely than younger patients (mean age 55 years) to undergo surgery (64 versus 86 percent). Older patients also had a significantly higher mortality with either surgery or medical therapy ( eg , in-hospital mortality 43 versus 28 percent). Mehta RH, o'gara PT, bossone E, et al. Acute type A aortic dissection in the elderly: clinical characteristics, management, and outcomes in the current era. J am coll cardiol 2002; 40:685

80. Mehta RH, o'gara PT, bossone E, et al. Acute type A aortic dissection in the elderly: clinical characteristics, management, and outcomes in the current era. J am coll cardiol 2002; 40:685

81. GENERAL PRINCIPLES The prognosis of patients requiring surgery improved dramatically in 1955 after DeBakey's introduction of effective surgical techniques. In addition, restoration of aortic valve competence can be performed in patients who develop significant aortic regurgitation. This can be achieved by resuspension of the native aortic valve or by aortic valve replacement. Medical therapy of aortic dissection involves lowering the blood pressure and decreasing the velocity of left ventricular contraction, both of which will decrease aortic shear stress and minimize the tendency for the dissection to propagate.

82. ACUTE MANAGEMENT

83. ACUTE MANAGEMENT 1. The primary goal of medical therapy is to decrease the force of left ventricular contraction ( dp / dt ) and systemic blood pressure, which are the main determinants of dissection extension and rupture. 2. B-blockers first, other antihypertensive such as vasodilators, and adequate analgesia (morphine) should be initiated to keep systolic blood pressure 120 mm hg and heart rate 60 bpm. 3. Patients with hemodynamic instability at presentation in whom aortic dissection is strongly suspected should be intubated and rapidly sent to diagnostic imaging and surgical therapy.

84. ACUTE MANAGEMENT

85. ACUTE MANAGEMENT For blood pressure control, initial treatment consists of an intravenous beta blocker to reduce the heart rate below 60 beats/min. Propranolol (1 to 10 mg load, followed by 3 mg/h) Labetalol as a bolus (20 mg initially, followed by 20 to 80 mg every 10 minutes to a total dose of 300 mg) or as an infusion (0.5 to 2 mg/min). Esmolol has advantages in the acute setting, due to its short half-life and can be used in patients who might be intolerant of beta blockers due, for example, to asthma, or heart failure.

86. ACUTE MANAGEMENT The patient can be switched to oral beta blocker therapy after heart rate control has been achieved.

87. ACUTE MANAGEMENT If, after beta blockade, the systolic blood pressure remains elevated Nitroprusside can be added, to achieve a systolic blood pressure of 100 to 120 mmHg. Blood pressure should be maintained at as low in this range as can be achieved without compromising mentation or urine output.

88. ACUTE MANAGEMENT The initial dose of nitroprusside is 0.25 to 0.5 mcg/kg per minute. Nitroprusside should not be used without first controlling the heart rate with beta blockade since vasodilation alone induces reflex activation of the sympathetic nervous system leading to enhanced ventricular contraction and increased aortic wall shear stress.

89. ACUTE MANAGEMENT While nitroprusside is the preferred agent, angiotensin converting enzyme (ACE) inhibitors or intravenous nicardipine , verapamil or diltiazem may also be effective in lowering blood pressure . Other direct vasodilators, such as hydralazine, should be avoided, since they increase aortic wall shear stress and provide less accurate and reversible control of the blood pressure.

90. ACUTE MANAGEMENT Hypotensive patients should be evaluated to determine if the cause is blood loss, hemopericardium with tamponade, valvular dysfunction, or left ventricular systolic dysfunction before volume is administered. Inotropic agents should be avoided since they will increase aortic wall shear stress and worsen the dissection.

91. DEFINITIVE THERAPY

92. Descending (type B) aortic dissection Medical therapy : patients with uncomplicated aortic dissections confined to the descending thoracic aorta ( stanford type B or debakey type III) are best treated with medical therapy. Erbel R, Alfonso F, Boileau C, et al. Diagnosis and management of aortic dissection. Eur Heart J 2001; 22:1642 Crawford ES. The diagnosis and management of aortic dissection. JAMA 1990; 264:2537..

93. Descending (type B) aortic dissection In a series of 384 patients with type B dissections from the IRAD, 73 percent were managed medically. In-hospital mortality for these patients was 10 percent [12]. Suzuki T, mehta RH, ince H, et al. Clinical profiles and outcomes of acute type B aortic dissection in the current era: lessons from the international registry of aortic dissection (IRAD). Circulation 2003; 108 suppl 1:II312.

94. Descending (type B) aortic dissection The reported long-term survival rate with medical therapy is approximately 60 to 80 percent at four to five years and approximately 40 to 45 percent at 10 years. Umaña JP, lai DT, mitchell RS, et al. Is medical therapy still the optimal treatment strategy for patients with acute type B aortic dissections? J thorac cardiovasc surg 2002; 124:896

95. Descending (type B) aortic dissection Intervention : Intervention (surgical or endovascular) for descending aortic dissection is reserved for patients who have a complicated course.

96. Descending (type B) aortic dissection Indications for intervention (surgical or endovascular) for type B dissection include : Occlusion of a major aortic branch leading to end-organ ischemia. Persistent severe hypertension or pain. Propagation of the dissection (as may be manifested by persistent or recurrent pain). Aneurysmal expansion. Rupture. Acute distal dissections in patients with Marfan Syndrome may also be best treated surgically.

97. Descending (type B) aortic dissection Because patients treated surgically are primarily those with a complicated course, it is not surprising that short-term mortality for these patients is higher than those managed with medical therapy. In data from the IRAD, in-hospital mortality for surgical patients was 32 percent compared with 10 percent for those treated medically. Umaña JP, lai DT, mitchell RS, et al. Is medical therapy still the optimal treatment strategy for patients with acute type B aortic dissections? J thorac cardiovasc surg 2002; 124:896

98. Descending (type B) aortic dissection There were two independent predictors of surgical mortality: age ≥70 years and hypotension or shock on admission . Trimarchi S, nienaber CA, rampoldi V, et al. Role and results of surgery in acute type B aortic dissection: insights from the international registry of acute aortic dissection (IRAD). Circulation 2006; 114:I357.

99. Descending (type B) aortic dissection Although short-term outcomes are better for medically treated patients with type B dissections, long-term outcomes may be similar. This was illustrated in a report of 142 patients, 111 (78 percent) of whom were treated medically. There was a trend toward lower mortality with medical therapy at one year (15 versus 33 percent); this difference tended to diminish over time. Both groups had similar survival at five and ten years (60 and 35 percent). Umaña JP, lai DT, mitchell RS, et al. Is medical therapy still the optimal treatment strategy for patients with acute type B aortic dissections? J thorac cardiovasc surg 2002; 124:896

100. Ascending (type A) aortic dissection Acute ascending aortic dissections ( stanford type A) should be treated as a surgical emergency since these patients are at high risk for a life-threatening complication such as aortic regurgitation, tamponade, and myocardial infarction with mortality rate as high as 1 to 2 percent per hour early after symptom onset.

101. Ascending (type A) aortic dissection The use of and survival benefit from surgery were illustrated in an IRAD review of 547 patients with a type A dissection: 80 percent of patients were treated surgically. The main cited reasons for medical therapy were comorbid conditions, advanced age (mean 80 years), and patient refusal. The in-hospital mortality was 27 and 56 percent for surgical and medical therapy, a difference that was due, in part, to increased comorbidity in medically treated patients. Not surprisingly, the patients who died had a higher rate of in-hospital complications including neurologic deficits, coronary or mesenteric ischemia, acute renal failure, and limb ischemia Mehta RH, Suzuki T, Hagan PG, et al. Predicting death in patients with acute type a aortic dissection. Circulation 2002; 105:200.

102. Ascending (type A) aortic dissection Mehta RH, suzuki T, hagan PG, et al. Predicting death in patients with acute type a aortic dissection. Circulation 2002; 105:200.

103. Ascending (type A) aortic dissection Even the presence of acute myocardial infarction, which may be due to the dissection involving a coronary ostium (particularly the right coronary artery), should not entirely exclude the option of rapid surgical intervention. Patients with stroke in progress are at increased risk for hemorrhagic cerebral infarction due to intraoperative heparinization and restoration of cerebral blood flow. Thus, hemorrhagic stroke is a relative contraindication to urgent surgical intervention.

104. Ascending (type A) aortic dissection Operative mortality for ascending aortic dissections at experienced centers varies from 7 to 36 percent.

105. Ascending (type A) aortic dissection Poor prognostic factors include: Age over 70 years. Abrupt onset of chest pain. Hypotension, shock, or tamponade at presentation. Renal failure at presentation and before surgery. Pulse deficit. Abnormal ECG, particularly ST segment elevation. Prior myocardial infarction.

106. Ascending (type A) aortic dissection Poor prognostic factors include: Previous aortic valve replacement. Renal and/ or visceral ischemia. Underlying pulmonary disease. Preoperative neurologic impairment. Perioperative bleeding and massive blood transfusion. Prolonged clamping time.

107. Evaluation for CAD and aortic valve disease In addition to the imaging necessary to secure the diagnosis of type A aortic dissection, CT coronary angiography, percutaneous coronary angiography and TEE may be considered to evaluate the patient for concomitant coronary artery disease (CAD) or aortic valve disease (TEE, MRI, transthoracic echocardiography) prior to urgent surgical repair of the ascending aorta.

108. Survival after repair Long-term survival after surgical repair of type A dissections is relatively good. This was illustrated in a series of 208 patients presenting between 1978 and 1995 patient survival at 5 and 10 years was 68 and 52 percent, respectively. Sabik JF, lytle BW, blackstone EH, et al. Long-term effectiveness of operations for ascending aortic dissections. J thorac cardiovasc surg 2000; 119:946.

109. Endovascular stent-grafts Endovascular stent-grafting has been employed as a less invasive alternative to surgery, primarily in patients with complicated type B dissections. The stent graft is positioned to cover the intimal flap and seal the entry site of the dissection, resulting in thrombosis of the false lumen.

110. Endovascular stent-grafts Type B dissections: The outcome of stent grafting was compared with surgery in a nonrandomized evaluation of 24 consecutive patients with a subacute or chronic thoracic type B dissection who had at least one indication for surgery. There was no morbidity (paraplegia, stroke, embolization, side-branch occlusion or infection) or mortality with stent grafting, while surgery was associated with a 33 percent mortality and a 42 percent incidence of adverse events within 12 months. At three months, thrombosis of the false lumen had occurred in all patients undergoing stent grafting. Nienaber CA, fattori R, lund G, et al. Nonsurgical reconstruction of thoracic aortic dissection by stent-graft placement. N engl J med 1999; 340:1539.

111. Endovascular stent-grafts Nienaber CA, fattori R, lund G, et al. Nonsurgical reconstruction of thoracic aortic dissection by stent-graft placement. N engl J med 1999; 340:1539.

112. Endovascular stent-grafts Stent grafting has also been evaluated for acute and, in some cases, life-threatening dissections, but the outcomes are not as good . One report evaluated 19 patients with an acute dissection (four type A) and an indication for surgery. This included involvement of aortic branches in 14, which led to symptomatic compromise of multiple branch vessels in 7. Complete thrombosis was achieved in 79 percent, and revascularization of ischemic branch vessels with relief of symptoms occurred in 76 percent of obstructed branches. However, the morbidity rate was 21 percent (small bowel and renal infarction and lower extremity gangrene) and 30-day mortality was 16 percent. Among patients who survived this period, there were no deaths or instances of aneurysm or aortic rupture during the subsequent 13-month follow-up period. Dake MD, kato N, mitchell RS, et al. Endovascular stent-graft placement for the treatment of acute aortic dissection. N engl J med 1999; 340:1546.

113. Endovascular stent-grafts Dake MD, kato N, mitchell RS, et al. Endovascular stent-graft placement for the treatment of acute aortic dissection. N engl J med 1999; 340:1546.

114. Endovascular stent-grafts In an attempt to overcome the small number of patients in most published series, a meta-analysis was performed of 39 studies involving a total of 609 patients who underwent stent-graft placement for a type B dissection . The following findings were noted: Procedure success was achieved in 98 percent of patients. Major complications occurred in 11.1 percent; neurologic complications, the most serious, occurred in 2.9 percent, mostly periprocedural stroke and paraplegia (1.9 and 0.8 percent, respectively). The major complication rate was significantly higher with acute compared with chronic dissections (21.7 versus 9.1 percent). The false lumen was not abolished in about 25 percent of patients and, at a mean follow-up of 19 months, aortic rupture occurred in 2.3 percent. The mortality rate was 5.2 percent in-hospital and 5.3 percent at 30 days, being significantly higher with acute dissections (9.8 versus 3.2 percent). Kaplan-Meier analysis revealed overall survival rates of 90 percent at one year and 89 percent at two years. Eggebrecht H, nienaber CA, neuhäuser M, et al. Endovascular stent-graft placement in aortic dissection: a meta-analysis. Eur heart J 2006; 27:489.

115. Endovascular stent-grafts Eggebrecht H, Nienaber CA, Neuhäuser M, et al. Endovascular stent-graft placement in aortic dissection: a meta-analysis. Eur Heart J 2006; 27:489.

116. Endovascular stent-grafts Type A dissections : A possible alternative to surgery in patients with type A dissections who have ischemic complications is endovascular stent-grafting . There is only a limited experience in patients with acute type A dissections.

117. PROGNOSIS The 10-year actuarial survival rate of patients with an aortic dissection who leave the hospital has ranged from 30 to 88 percent. survival appears similar for both type A and type B dissections . Late aneurysm formation and adverse outcomes, including death, are related to the initial diameter of the false lumen in the upper thoracic aorta. Patients with an initial false lumen diameter of ≥22 mm at the upper thoracic aorta, compared with those with a smaller diameter, were significantly more likely to develop late aneurysm formation or death.

118. LONG-TERM MANAGEMENT There are three main management issues in patients who have survived the initial dissection: Medical therapy to minimize aortic wall shear stress. Serial imaging to detect signs of dissection progression, re-dissection, or aneurysm formation. Reoperation when indicated.

119. LONG-TERM MANAGEMENT Medical therapy : All patients should receive life-long therapy with an oral beta blocker to reduce systemic blood pressure and the rate, both of which will minimize aortic wall stress. Although not evaluated in controlled trials (target BPof less than 120/80 mmHg). Avoidance of strenuous physical activity is also recommended as another method to minimize aortic shear stress.

120. LONG-TERM MANAGEMENT Serial imaging : we generally perform a baseline thoracic MRI or chest CT scan prior to discharge with follow-up examinations at 3, 6, and 12 months, even if the patient remains asymptomatic . Subsequent screening studies are then performed every one to two years if there is no evidence of progression.

121. LONG-TERM MANAGEMENT Reoperation : Repeat surgery is required in 12 to 30 percent of patients, usually because of extension or recurrence of dissection at the previous site of intervention, localized aneurysm formation remote from the site of repair, graft dehiscence or infection, or aortic regurgitation. The reoperation rate is higher in patients with Marfan syndrome.