Urgent matter—emergency treatment of aortic dissection

Most patients with acute aortic dissection are men aged 60-80 years, and systemic hypertension is the most important susceptibility factor to acute aortic dissection [2, 3]. 72% of patients had a history of hypertension and 31% had a history of atherosclerosis.

1. Classification

There are currently two different anatomical systems available for classifying aortic dissection, namely the DeBakey classification system and the Daily (Stanford) classification system [4, 5]. The Stanford classification system is more widely used. In this classification system, dissections involving the ascending aorta, regardless of the location of the initial intimal tear, are classified as type A, and all other dissections are classified as type B. In contrast, the DeBakey system classification is based on the starting point of the dissection. Type 1 originates from the ascending aorta and extends to at least the aortic arch; type 2 originates from the ascending aorta and is limited to the ascending aorta; type 3 originates from the descending aorta and extends to at least the aortic arch. Expand proximally or distally.

2. Emergency medical treatment

Emergency medical management of aortic dissection includes analgesia and rate control therapy to lower blood pressure and reduce left ventricular systolic velocity to reduce aortic shear stress and minimize the tendency of dissection extension.

1. Control of ventricular rate and blood pressure

Rate control therapy aims to reduce left ventricular contraction velocity, thereby reducing shear stress and minimizing lesion progression [6]. The common method is intravenous infusion of beta-blockers. Systolic blood pressure should be reduced to the lowest level that the patient can tolerate without affecting mental status and urine output, generally to 100-120mmHg.

Initial treatment usually involves intravenous infusion of beta-blockers to reduce the heart rate to less than 60 beats/minute. Esmolol can be used in acute situations because of its short half-life and the ability to adjust the dose to an onset of action of 250-500 μg/kg loading dose, given over 1 minute, and then infused at a rate of 25-50 μg/(kg·min) Note; the maximum dose is 300 μg/(kg·min)]. Patients who cannot tolerate beta-blockers can use diltiazem or verapamil [2].

If beta-blockers fail to sufficiently reduce systolic blood pressure, intravenous nicardipine, ACEI, verapamil, or diltiazem can be used in combination [6]. Other direct vasodilators (such as hydralazine) should not be used because they increase shear stress in the aortic wall and make precise and reversible blood pressure control more difficult.

2.Analgesia

Intravenous opioids are usually given for analgesic treatment, and the commonly used dosage forms are continuous intravenous pump infusion or intermittent administration of fentanyl. If optimal medical therapy fails to control pain in patients with aortic dissection, outcomes may be worse [7]. However, recurrence of pain is not necessarily related to failure of medical treatment.

3. Types and causes of dissection

Acute type A aortic dissection is a surgical emergency; acute type B aortic dissection usually does not require emergency surgery unless the patient has complications such as end-organ malperfusion, intractable pain, rapid expansion of the false lumen, and imminent or obvious rupture.

1. Ascending aortic dissection (type A)

Acute type A aortic dissection is a surgical emergency because patients are at high risk for life-threatening complications such as aortic regurgitation, cardiac tamponade, stroke, overt rupture, and myocardial infarction. If no surgical intervention is performed after the onset of symptoms, the early mortality rate is as high as 1%-2% per hour [8]. After type A dissection is diagnosed, only patients with a life expectancy of less than 1 year may not undergo surgery. Hemorrhagic stroke is a relative contraindication to emergency surgery.

2. Descending aortic dissection (type B)

The initial treatment of type B dissection generally adopts medical methods, and surgery is only used in patients with dissection complications, such as dissection extension and poor perfusion [9, 10]. However, more and more doctors are beginning to consider endovascular treatment of type B aortic dissection before poor perfusion, which may reduce the incidence of long-term aortic dilation [11].

Some physicians have suggested that in patients with acute type B dissection without malperfusion or other complications, endoluminal intervention has the potential to improve long-term outcomes by improving the relationship between the true and false lumens and eliminating complications that may otherwise occur if left untreated. Anatomical structures that contribute to long-term complications and death. But the overall results of these studies suggest that the best treatment is a targeted approach to complications of type B dissection.

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References:

[1]. Nienaber, C.A. and K.A. Eagle, Aortic dissection: new frontiers in diagnosis and management: Part I: from etiology to diagnostic strategies. Circulation, 2003. 108(5): p. 628-35.

[2]. Spittell, P.C., et al., Clinical features and differential diagnosis of aortic dissection: experience with 236 cases (1980 through 1990). Mayo Clin Proc, 1993. 68(7): p. 642-51.

[3]. Larson, E.W. and W.D. Edwards, Risk factors for aortic dissection: a necropsy study of 161 cases. Am J Cardiol, 1984. 53(6): p. 849-55.

[4]. Tsai, T.T., C.A. Nienaber and K.A. Eagle, Acute aortic syndromes. Circulation, 2005. 112(24): p. 3802-13.

[5]. DEBAKEY, M.E., et al., SURGICAL MANAGEMENT OF DISSECTING ANEURYSMS OF THE AORTA. J Thorac Cardiovasc Surg, 1965. 49: p. 130-49.

[6]. Di Eusanio, M., et al., Clinical presentation, management, and short-term outcome of patients with type A acute dissection complicated by mesenteric malperfusion: observations from the International Registry of Acute Aortic Dissection. J Thorac Cardiovasc Surg , 2013. 145(2): p. 385-390.e1.

[7].. Trimarchi, S., et al., Importance of refractory pain and hypertension in acute type B aortic dissection: insights from the International Registry of Acute Aortic Dissection (IRAD). Circulation, 2010. 122(13): p . 1283-9.

[8]. Nienaber, C.A. and K.A. Eagle, Aortic dissection: new frontiers in diagnosis and management: Part I: from etiology to diagnostic strategies. Circulation, 2003. 108(5): p. 628-35.

[9]. Erbel, R., et al., Diagnosis and management of aortic dissection. Eur Heart J, 2001. 22(18): p. 1642-81.

[10]. Doroghazi, R.M., et al., Long-term survival of patients with treated aortic dissection. J Am Coll Cardiol, 1984. 3(4): p. 1026-34.

[11]. Nienaber, C.A., et al., Randomized comparison of strategies for type B aortic dissection: the INvestigation of STent Grafts in Aortic Dissection (INSTEAD) trial. Circulation, 2009. 120(25): p. 2519-28.