Question 16

Regarding Deep Hypothermic Circulatory Arrest (DHCA) during cardiac surgery:

a)    Explain the rationale for DHCA.    (30% marks)

b)    List six indications for DHCA.    (30% marks)

c)    Outline the adverse effects of DHCA that may be encountered in ICU post DHCA.
(40% marks)
 

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College answer

Not available.

Discussion

a) Rationale:

  • Surgical access
    • The surgical approach to the replacement or repair of the aortic arch and aortic root requires that at some stage the aorta be incised and open to air.
    • It is impractical to do this with normal circulation: air emboli and blood loss would be prohibitive
    • Circulation must therefore cease while the aortic root is opened
  • Organ protection
    • Hypothermia protects the organs during circulatory arrest
    • This is the result of a decreased metabolic rate
    • At 18º C, cerebral metabolic rate decreases to something like 10-15% of the normal rate seen at 37º C
    • At this temperature, complete circulatory arrest can be well tolerated for up to 30 minutes

b) Indications:

  • Cardiac surgery:
    • Aortic arch reconstruction (aneurysm, rupture, dissection)
    • Pulmonary thromboendarterectomy
    • Repair of complex congenital heart defects (transposition of the great arteries, total anomalous pulmonary venous return, hypoplastic left heart syndrome)
    • Vascular reconstruction during cardiac transplant
  • Non-cardiac surgery:
    • Surgery on the thoracoabdominal aorta
    • Repair of giant cerebral aneurysms
    • Resection of cerebral arteriovenous malformations
    • Resection of renal cell carcinoma with caval invasion
    • Resection of other tumors with caval invasion

c) Adverse effects:

  • Respiratory complications:
    • Hypoxia due to atelectasis
    • ARDS (if prolonged bypass)
  • Circulatory complications:
    • Low cardiac output states (if prolonged bypass time)
    • Arrhythmias (especially if incompletely rewarmed)
  • Neurological complications:
    • Stroke (mainly embolic, and mainly in those who had more than 40 minutes of DHCA)
    • Seizures
    • Choreoathetosis (usually develops 2-6 days following the surgery; seems to be related to temperatures below 15º C)
    • Decreased cognitive function
    • Spinal cord ischaemia 
  • Renal complications
    • Acute kidney injury
  • Hepatic complications:
    • LFT derangement
  • Haematological complications:
    • Coagulopathy 

References

Conolly, Sarah, Joseph E. Arrowsmith, and Andrew A. Klein. "Deep hypothermic circulatory arrest." Continuing Education in Anaesthesia, Critical Care & Pain 10.5 (2010): 138-142.

Ziganshin, Bulat A., and John A. Elefteriades. "Deep hypothermic circulatory arrest." Annals of cardiothoracic surgery 2.3 (2013): 303.

Ziganshin, Bulat A., et al. "Straight deep hypothermic circulatory arrest for cerebral protection during aortic arch surgery: safe and effective." The Journal of thoracic and cardiovascular surgery 148.3 (2014): 888-900.