Revision as of 14:36, 6 November 2012 by Raviteja Reddy Guddeti(talk | contribs)(/* Blood Pressure Control (DO NOT EDIT) {{cite journal| author=Hiratzka LF, Bakris GL, Beckman JA, Bersin RM, Carr VF, Casey DE et al.| title=2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM guidelines for the diagnosis and management of patients w...)
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
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
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.
All patients should have an arterial line in the arm with the higher BP for accurate monitoring.
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.
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.
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.
Pain control with morphine is important in so far as it reduces sympathetic tone, heart rate and blood pressure.
Step 3: Blood Pressure Control
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.
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.
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.
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
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.
Acute thoracic aortic dissection of the descending aorta (Type B dissection) should be managed medically unless and of the following morbid / mortal complications develop:
Malperfusion syndrome
Further propagation of the dissection
Further rapid aneurysm expansion
Blood pressure lability suggestive of renal artery involvement
For patients with DeBakey III or Daily B dissections, medical therapy offers an > 80% survival rate.
Step 5: Chronic Therapy
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 pressure below 130 mmHg.
2010 ACCF/AHA/AATS/ACR/ASA/SCA/SCAI/SIR/STS/SVM Guidelines for the Evaluation and Management of Aortic Dissection (DO NOT EDIT) [1]
"1. Initial management of thoracic aortic dissection should be directed at decreasing aortic wall stress by controlling heart rate and blood pressure as follows":"
"a. In the absence of contraindications, intravenous beta blockade should be initiated and titrated to a target heart rate of 60 beats per minute or less. (Level of Evidence: C)"
"b. In patients with clear contraindications to beta blockade, nondihydropyridine calcium channel–blocking agents should be utilized as an alternative for rate control. (Level of Evidence: C)"
"c. If systolic blood pressures remain greater than 120 mm Hg after adequate heart rate control has been obtained, then angiotensin-converting enzyme inhibitors and/or other vasodilators should be administered intravenously to further reduce blood pressure that maintains adequate end-organ perfusion. (Level of Evidence:C)"
"1.Vasodilator therapy should not be initiated prior to rate control so as to avoid associated reflex tachycardia that may increase aortic wall stress, leading to propagation or expansion of a thoracic aortic dissection. (Level of Evidence: C)"
"1. Urgent surgical consultation should be obtained for all patients diagnosed with thoracic aortic dissection regardless of the anatomic location (ascending versus descending) as soon as the diagnosis is made or highly suspected. (Level of Evidence: C)"
"2. Acute thoracic aortic dissection involving the ascending aorta should be urgently evaluated for emergent surgical repair because of the high risk of associated life-threatening complications such as rupture[2]. (Level of Evidence: B)"
"3. Acute thoracic aortic dissection involving the descending aorta should be managed medically unless life-threatening complications develop (e.g., malperfusion syndrome, progression of dissection, enlarging aneurysm, inability to control blood pressure or symptoms)[3][4][5][6][7][8]. (Level of Evidence: B)"
Medical Treatment of Patients with Thoracic Aortic Diseases (DO NOT EDIT) [1]
"1. Stringent control of hypertension, lipid profile optimization, smoking cessation, and other atherosclerosis risk-reduction measures should be instituted for patients with small aneurysms not requiring surgery, as well as for patients who are not considered surgical or stent graft candidates. (Level of Evidence: A)"
"1. Treatment with a statin to achieve a target LDL cholesterol of less than 70 mg/dL is reasonable for patients with a coronary heart disease risk equivalent such as noncoronary atherosclerotic disease, atherosclerotic aortic aneurysm, and coexistent coronary heart disease at high risk for coronary ischemic events. (Level of Evidence:A)"
"1.Smoking cessation and avoidance of exposure to environmental tobacco smoke at work and home are recommended. Follow-up, referral to special programs, and/or pharmacotherapy (including nicotine replacement, buproprion, or varenicline) is useful, as is adopting a stepwise strategy aimed at smoking cessation (the 5 As are Ask, Advise, Assess, Assist, and Arrange). (Level of Evidence: B)"
Aortic Arch and Thoracic Aortic Atheroma and Atheroembolic Disease (DO NOT EDIT) [1]
"1. Oral anticoagulation therapy with warfarin (INR 2.0 to 3.0) or antiplatelet therapy may be considered in stroke patients with aortic arch atheroma 4.0 mm or greater to prevent recurrent stroke. (Level of Evidence: C)"
↑Hagan PG, Nienaber CA, Isselbacher EM; et al. (2000). "The International Registry of Acute Aortic Dissection (IRAD): new insights into an old disease". JAMA. 283 (7): 897–903. PMID10685714. Unknown parameter |month= ignored (help)CS1 maint: Explicit use of et al. (link) CS1 maint: Multiple names: authors list (link)
↑Mehta RH, O'Gara PT, Bossone E; et al. (2002). "Acute type A aortic dissection in the elderly: clinical characteristics, management, and outcomes in the current era". J. Am. Coll. Cardiol. 40 (4): 685–92. PMID12204498. Unknown parameter |month= ignored (help)CS1 maint: Explicit use of et al. (link) CS1 maint: Multiple names: authors list (link)
↑Suzuki T, Mehta RH, Ince H; et al. (2003). "Clinical profiles and outcomes of acute type B aortic dissection in the current era: lessons from the International Registry of Aortic Dissection (IRAD)". Circulation. 108 Suppl 1: II312–7. doi:10.1161/01.cir.0000087386.07204.09. PMID12970252. Unknown parameter |month= ignored (help)CS1 maint: Explicit use of et al. (link) CS1 maint: Multiple names: authors list (link)
↑Estrera AL, Miller CC, Safi HJ; et al. (2006). "Outcomes of medical management of acute type B aortic dissection". Circulation. 114 (1 Suppl): I384–9. doi:10.1161/CIRCULATIONAHA.105.001479. PMID16820605. Unknown parameter |month= ignored (help)CS1 maint: Explicit use of et al. (link) CS1 maint: Multiple names: authors list (link)
↑Umaña JP, Lai DT, Mitchell RS; et al. (2002). "Is medical therapy still the optimal treatment strategy for patients with acute type B aortic dissections?". J. Thorac. Cardiovasc. Surg. 124 (5): 896–910. PMID12407372. Unknown parameter |month= ignored (help)CS1 maint: Explicit use of et al. (link) CS1 maint: Multiple names: authors list (link)
↑Mehta RH, Suzuki T, Hagan PG; et al. (2002). "Predicting death in patients with acute type a aortic dissection". Circulation. 105 (2): 200–6. PMID11790701. Unknown parameter |month= ignored (help)CS1 maint: Explicit use of et al. (link) CS1 maint: Multiple names: authors list (link)
↑Chiappini B, Schepens M, Tan E; et al. (2005). "Early and late outcomes of acute type A aortic dissection: analysis of risk factors in 487 consecutive patients". Eur. Heart J. 26 (2): 180–6. doi:10.1093/eurheartj/ehi024. PMID15618075. Unknown parameter |month= ignored (help)CS1 maint: Explicit use of et al. (link) CS1 maint: Multiple names: authors list (link)