Management of acute aortic dissection in critical care

Abstract

Aortic dissections are associated with significant mortality and morbidity, with rapid treatment paramount. They are caused by a tear in the intimal lining of the aorta that extends into the media of the wall. Blood flow through this tear leads to the formation of a false passage bordered by the inner and outer layers of the media. Their diagnosis is challenging, with most deaths caused by aortic dissection diagnosed at post-mortem. Aortic dissections are classified by location and chronicity, with management strategies depending on the nature of the dissection. The Stanford method splits aortic dissections into type A and B, with type A dissections involving the ascending aorta. De Bakey classifies dissections into I, II or III depending on their origin and involvement and degree of extension. The key to diagnosis is early suspicion, appropriate imaging and rapid initiation of treatment. Treatment focuses on initial resuscitation, transfer (if possible and required) to a suitable specialist centre, strict blood pressure and heart rate control and potentially surgical intervention depending on the type and complexity of the dissection. Effective post-operative care is extremely important, with awareness of potential post-operative complications and a multi-disciplinary rehabilitation approach required. In this review article we will discuss the aetiology and classifications of aortic dissection, their diagnosis and treatment principles relevant to critical care. Critical care clinicians play a key part in all these steps, from diagnosis through to post-operative care, and thus a thorough understanding is vital.

Keywords: Aortic dissection; anaesthesia; aortopathy; critical care; intensive care.

Figure 1.

Classification of aortic dissections.

Figure 2.

Computed tomographic images demonstrating the ‘tennis ball’ sign in (i) a type A dissection and (ii) a type B dissection. Source: Cases courtesy of Assoc Prof Frank Gaillard, Radiopaedia.org, rID: 8886 and rID:8935.

Figure 3.

Transthoracic echocardiographic view of a dilated aortic root with an ascending aortic dissection and severe aortic regurgitation.

Figure 4.

Flow chart for the initial management of an acute aortic dissection.

Figure 5.

Demonstration of arterial waves forms and the effect of pharmacological agents. (i) Baseline arterial wave form, dp/dt represents the shear force which is a result of the change in pressure over tie; (ii) the background light red line is the baseline arterial wave form, the superimposed green line is the waveform after the use of vasodilators – leading to a reduction in blood pressure (BP) but an increase in heart rate and dP/dt; (iii) again the background light red line is the baseline arterial wave form and the purple line here represents the waveform following beta-blocker treatment – leading to a reduction in BP and heart rate and with this a reduction in dP/dt. Source: Adapted from https://ucsfmed.wordpress.com/2020/10/04/in-aortic-dissection-drop-the-dp-dt/.