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Here's the puzzle. Your patient has an acute type A dissection, so the ascending aorta is torn. To do cardiac surgery you need to cannulate the aorta and cross-clamp it — but the ascending aorta is both dissected and the thing you're about to operate on. So you can't cannulate it, and you can't clamp it. What do you do?
The answer is that you cool the patient right down and stop the circulation altogether. In this episode Mike and Calum work through major aortic surgery and deep hypothermic circulatory arrest — the theatre half of the topic. The ICU half, on hypertensive emergencies and acute aortic syndromes, is the previous episode.
Please note: the drugs and doses discussed are Wythenshawe-specific local practice. Take the principles, and check your own guidelines for the numbers.
We start with the arrest itself: why the anaesthetist stays in the room, cooling to 18°C with ice packed round the head, and thiopentone to drop the cerebral metabolic rate. Then cannulation — femoral or right axillary — and the trap that follows, because if they clamp the right axillary artery your arterial line and saturation probe need to be on the left. We cover selective antegrade cerebral perfusion, why cerebral oximetry is your window on the only organ you can't afford to lose, and what the anaesthetist, perfusionist and surgeon can each do about low cerebral saturations.
Then rewarming, and a strong opinion: after circulatory arrest, the nasopharyngeal probe tells you a comfortable lie. Believe it and you'll come off bypass cold, and hand over a patient who then cools further, drops their cardiac output and becomes vasoplegic and coagulopathic. Wait for the bladder temperature.
The centrepiece is an echo walkthrough of the aortic root, because it directly decides the operation. The four levels of the root, the two workhorse views, and the question that actually matters — not how badly the valve leaks, but why. We work through the three mechanisms of aortic regurgitation in dissection (a dilated root pulling normal cusps apart, a commissure stripped off the wall by the flap, and the flap itself prolapsing through), all of which mean the valve is a victim rather than the culprit and can potentially be saved. Then what forces replacement, why an unstable patient may be better served by a quicker operation, and how to scan the finished repair.
We finish with DOAC reversal and why certainty at the bedside beats elegance in a paper, washing jets versus paravalvular leaks, postoperative goals, and where CSF drainage fits for descending aortic work.
Chapters
- (00:00) Cold open — the aorta you can't clamp
- (01:30) Cooling to 18°C: how the arrest protects the brain
- (03:20) Cannulation, and why your art line goes on the left
- (05:00) Cerebral perfusion, oximetry and low saturations
- (06:40) Knowing the surgeon's plan — the essence of cardiac anaesthesia
- (07:40) The cross-clamp, and why there isn't one during arrest
- (08:40) Rewarming: the temperature probe that lies to you
- (10:30) Echo deep dive: the four levels of the aortic root
- (12:00) The views — and asking why it leaks, not how badly
- (13:30) Three mechanisms of AR: the valve as victim
- (15:00) When to replace, and why time changes the operation
- (16:30) What else to report: ostia, tamponade, entry tear
- (17:40) Scanning the finished repair
- (18:40) They've arrived on a DOAC
- (20:00) Washing jets versus paravalvular leaks
- (21:00) Postoperative goals and CSF drainage
- (22:00) Wrap-up
Key takeaways
- You cannot cannulate or clamp an aorta that is both dissected and the operative site — hence circulatory arrest
- Cool to 18°C, ice the head, and give thiopentone: both cooling and barbiturate reduce cerebral oxygen demand
- If the return goes to the right axillary artery, put your arterial line and saturation probe on the left
- During the arrest itself there is no cross-clamp at all — nothing is flowing
- Cerebral oximetry is your window on the brain, and low saturations are a three-way conversation
- Do not trust the nasopharyngeal temperature — wait for a bladder temperature of 36.5–37°C
- On echo, the surgeon needs to know why the valve leaks, not how badly
- A dilated root, a stripped commissure or a prolapsing flap all mean the valve is repairable
- Intrinsically diseased cusps or a destroyed annulus mean replacement — and an unstable patient may need the quicker operation
- Octaplex for DOAC reversal: we know it works, and it's at the bedside
- Washing jets are normal; if they're coagulopathic, leave the chest open
References / further reading
- Isselbacher EM et al. 2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease. Circulation2022
- Erbel R et al. 2014 ESC Guidelines on the diagnosis and treatment of aortic diseases. Eur Heart J 2014
- Boodhwani M et al. Repair-oriented classification of aortic insufficiency. J Thorac Cardiovasc Surg 2009
- Schäfers HJ et al. Cusp geometry and effective height in aortic valve repair. J Thorac Cardiovasc Surg 2006
- Hahn RT et al. Guidelines for performing a comprehensive transoesophageal echocardiographic examination. J Am Soc Echocardiogr 2013
- Davies EA, Charlesworth M, Agarwal S. Hypertensive emergencies. BJA Education 2024
- Boer C et al. EACTS/EACTA Guidelines on patient blood management for adult cardiac surgery. 2017
This podcast is for medical education for healthcare professionals. It is not clinical advice. All drugs and doses discussed reflect local Wythenshawe practice at the time of recording — always follow your own centre's guidelines and current local policy.
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