**8. Peri-aortic dissection before Going on CPB and after cardiac arrest**


**69**

*Current and Future Management Strategies of Type A Aortic Dissection*

8.Clamp the aorta somewhere in the mid-ascending aorta, which will be

eventually resected while doing open distal anastomoses. This allows assessment of the site of the tear and of the aortic root and also minimises the total

9.While excising the dissected ascending aorta, it is important to avoid injury to

10.While dissecting towards aortic root, left and right coronary ostia are identified and coronary buttons prepared (if aortic root replacement is planned).

**9. Hypothermic circulatory cardiac arrest and cerebral protection** 

Because of the low threshold tolerance to ischemia, brain protection is of paramount importance during aortic arch procedures. Hypothermia is an option to increase the ischemic time. However, there are limitations of hypothermia and hypothermic circulatory arrest. Protective effects of hypothermia last no more than 9 minutes at 30°, 14 minutes at 25°, 21 minutes at 2°, 31 minutes at 15° and 45 minutes at 10° [28]. Neurological deficits are seen in elderly patients subjected to

Several cerebral perfusion techniques have been introduced to extend the safe period of arch repair without residual neurological deficits. Retrograde cerebral perfusion (RCP) in tandem with hypothermic circulatory arrest was introduced in 1990 by Ueda et al. [29] Because the cerebral venous sinuses have no valves, RCP was proposed to provide retrograde perfusion and cooling of central nervous system (CNS). It offered to back-flush air emboli and debris from the cerebral circulation. Neuroprotective effects were most likely related to cooling rather than true nutritive flow [30]. It was also found to provide limited benefit in patients with significant carotid stenosis and vascular anomalies (e.g. an

Antegrade selective cerebral perfusion (SCP) was introduced by Jean Bachet and Daniel Guilmet in Europe [32] and by Teruhisa Kazui in Japan in 1986 [33]. This new perfusion method of "cold cerebroplegia" in combination with hypothermia significantly reduced neurologic complications. Antegrade selective perfusion can be established either by direct cannulation or by anastomosing a prosthetic graft. The options for locating such are (i) right subclavian artery, (ii) innominate artery, (iii) right common carotid artery. These may be combined with left common carotid artery cannulation to provide bilateral antegrade cerebral perfusion.

*DOI: http://dx.doi.org/10.5772/intechopen.93015*

circulatory arrest time.

*Aortic rupture prior to establishing CPB.*

**strategies**

**Figure 8.**

the main and right pulmonary artery.

hypothermic circulatory arrest exceeding 25 minutes.

incomplete Circle of Willis) [31].

**Figure 7.** *The dissected ascending aorta.*

*Current and Future Management Strategies of Type A Aortic Dissection DOI: http://dx.doi.org/10.5772/intechopen.93015*

**Figure 8.** *Aortic rupture prior to establishing CPB.*

*Advances in Complex Valvular Disease*

cooled to 22–24°C.

cannulated axillary artery.

dissecting ascending aorta.

established quickly in unstable patients and (ii) antegrade flow. Disadvantages include (i) rupture of cannulation site and (ii) false lumen perfusion [27].

**8. Peri-aortic dissection before Going on CPB and after cardiac arrest**

1.An expeditious midline sternotomy should be done with SBP maintained

be prepared to quickly place the two-stage cannula into right atrium.

blood seeping through adventitial layers (**Figure 7**).

around 100–110 mmHg. The dissected aorta is usually dilated, thinned out and

2.Upon opening the pericardium, be prepared for free aortic rupture (**Figure 8**). To minimise the risk either (i) femoral arterial and venous cannula should be in place or (ii) if axillary artery cannulation is done, then the surgeon should

3.Patient is cooled to a core temperature of 26–28°C. For hemi-arch replacement and short duration of total hypothermic circulatory arrest, 27°C temperature is optimum. If total arch replacement is planned, then the patient can be further

4.After going on CPB, a left ventricular vent is placed to prevent left ventricular distension due to associated acute aortic regurgitation. Retrogarde cardioplegia catheter is placed to arrest the heart, as antegrade cardioplegic arrest may not be possible due to aortic regurgitation. After the cardiac arrest and upon

opening the aorta, antegrade ostial cardioplegia can be administered.

5.If the patient is stable, innominate artery is carefully dissected and looped with a vascular loop before going on CPB. This can be occluded or clamped later to provide antegrade cerebral perfusion through the previously

6.After going on CPB, the aorta is dissected free from surrounding adhesions. When creating the plane between ascending aorta and main pulmonary artery,

7.It is important to identify right pulmonary artery and avoid injuring it, while

it is important to retain as much adventitial tissue on the aortic side.

**68**

**Figure 7.**

*The dissected ascending aorta.*

