Heart transplant

Question 1

What’s the 1, 5 & >=20yr survival in adults after heart transplant?

Answer 1

90, 70, 20%

Question 2

Across which timeframes do anaesthetic considerations differ in particular?

Answer 2

6-12/12 post-transplant vs later (<12/12)

Question 3

Why are elective surgical procedures typically deferred to >6-12/12 after heart transplant?

Answer 3

Greater risk of:

• acute rejection
• immunosuppression-related complications
• infection
• exacerbation of comorbidities including renal & liver dysfunction, steroid-induced DM, HTN which may require Rx (typically ACE-Is or ARBs), pulmonary diseases (particularly if had a Hx prolonged ventilatory support; suggests risk for postoperative respiratory failure. CXR & PFTs are reviewed during pre-anaes Ax.

Question 4

If elective surgery must be performed in the early post-transplant period, what investigations are done to check for graft function?

Answer 4

acute graft dysfunction may be due to ischemia or rejection.
Assess:
signs of RV dysfunction
ecg
echo
angiograms
BNP
endomyocardial biopsy +/- gene expression profiling

Question 5

If elective surgery must be performed in the early post-transplant period, what investigations are done to check for immunosuppression-related complications? Why is this relevant in particular in the 6-12/12 post-transplant?

Answer 5

Higher therapeutic level targets for immunosuppressive meds during the first 3-6/12, requiring adrenal suppression prophylaxis
Patient should ideally be on a stable immunosuppressive regimen prior to elective surgery, any active infection should be treated

Immunosuppression-related complications include:

• renal dysfunction from calcineurin inhibitors
• steroid-induced diabetes
• steroid-induced myopathy
• leukopenia
• infection

Question 6

What are some risk factors for renal dysfunction in heart transplant recipients?

Answer 6

• pre-op CCF–> chronic renal hypoperfusion
• post-transplant nephrotoxic immunosuppressive regimens
• repeated exposure to contrast during cardiac catheterisation procedures

note baseline Cr, GFR, urinalysis, spot urine ACR

Question 7

What are some risk factors for hepatic dysfunction in heart transplant recipients?

Answer 7

• congestive hepatopathy due to pre-transplant heart failure (may improve post-transplant due to improved CO); in particular, pts who had a Fontan procedure then heart transplant may have had congestive hepatopathy & fibrosis or cirrhosis
• hepatotoxic antiarrhythmics such as amiodarone
• MELD scores useful in determining severity of liver disease prior to non cardiac surgery in adults

Ax:
LFTs:
PT/INR
bilirubin
AST, ALT

Question 8

What are particular anaesthetic considerations in the late (>12/12) post-heart transplantation period?

Answer 8

Risk of acute rejection has diminished
immunosuppressive regimen has usually stabilised

Primary concerns=
allograft vasculopathy
stability of immunosuppressive regimen
risk of malignancy including post-transplant lymphoproliferative disease due to high-dose immunosuppression; these may involve airway so examine for S&S of airway obstruction or potentially difficult airway

Question 9

*What are some of the consequences of cardiac autonomic denervation due to explantation of the native heart during transplantation?

Answer 9

• graft heart usually has a higher resting HR (90-130bpm) cf native heart due to lack of PSNS innervation; HR may vary depending on age of graft
• baroreceptor reflexes lost (lack compensatory reflex tachycardia response to vasodilatory induction agents or other factors reducing MAP); DIRECT-acting vasopressors (eg, phenylephrine) and inotropes are effective to treat hypoT as intrinsic alpha & beta receptors in the grafted heart are intact as on peripheral vessels
• exaggerated hypotensive responses to vasodilators (GTN, hydralazine & vasodilatory induction agents) & no compensatory reflex tachycardia response; careful incremental induction with direct-acting vasopressor running
• starling effect IS retained (denervated heart responds to increases in preload with increased SV & CO; denervated heart extremely dependent on adequate IV volume & preload)
• during episodes of myocardial ischaemia, classic chest pain may not be experienced (no visceral innervation)- 5-lead ecg & high index of suspicion periop for myocardial ischaemia
• carotid massage & valsalva not effective
• anticholinergic medications (atropine, glycopyrrolate) won’t effectively treat bradycardia; direct-acting chronotropic agents (eg. isoprenaline, dobutamine, adrenaline) will, or techniques such as electrical pacing are effective for bradyarrhythmias
• anticholinesterases (eg. neostigmine) won’t cause bradycardia but rarely, advanced HB & asystole have been reported if neostigmine given to heart transplant recipients (may be due to PSNS innervation of the transplanted heart over time)
• digoxin won’t have any rate-controlling effects but retains it’s inotropic effect
• AVOID adenosine; has prolonged & profound bradycardic effect on denervated heart
• NMBDs (sux, pancuronium) won’t exert effects on HR
• sugammadex should be used with caution in heart transplant (although it doesn’t have cholinergic effects)