24.4 Heart Transplant

Question 1

A 56-year-old man is listed for elective surgery. He received an orthotopic heart transplant 12 years
before.
a) What key alterations in cardiac physiology and function must be considered when planning general
anaesthesia? (50%)

Answer 1

1&raquo_space; Cardiac allograft vasculopathy:
immunologically and non-immunologically

(hyperlipidaemia, hypertension, hyperglycaemia) mediated.

Heart is denervated so may present at a
late stage with
e.g. arrhythmias or left ventricular dysfunction.

Must maintain coronary perfusion pressure
and consider myocardial oxygen demand perioperatively.

Patients are followed up with echo (function), endomyocardial biopsy (rejection)
and
surveillance angiogram (coronary artery disease).

2&raquo_space; Permanent pacemaker:
the heart rate is dependent on donor sinoatrial
node activity.

Surgical disruption to blood supply during transplantation may cause persistent bradycardia necessitating pacemaker insertion.

3&raquo_space; Conduction abnormalities:
due to surgical disruption to blood supply
to atrioventricular node or other conduction pathways.

Detection of intraoperative ischaemia
may therefore be difficult.

4&raquo_space; Loss of autonomic innervation:

• Loss of vagal tone.
Resting heart rate is 90–100/minute due to
ongoing effect of circulating catecholamines.

• The heart rate response to intraoperative triggers such as laryngoscopy, pain, or light anaesthesia is lost.

• Loss of baroreceptor reflex:
if systemic vascular resistance drops due
to anaesthetic drugs,
there is no compensatory heart rate increase.

Starling’s law therefore determines cardiac output – it is therefore important to maintain preload.

5&raquo_space; Denervation effects on pharmacology:
• Heart is denervated.
Atropine, glycopyrrolate, neostigmine and
suxamethonium have no effect on heart rate
.
• Denervation supersensitivity to adrenaline, noradrenaline, adenosine.

Question 2

b) What are the implications of the patient’s immunosuppressant therapy for perioperative care? (30%)

Answer 2

Common combination = antimetabolite (azathioprine, mycofenolate mofetil) +
antiproliferative (tacrolimus, cyclosporin) + steroid

Important to maintain consistent plasma levels
in perioperative period to avoid rejection:
» Consider period of starvation, suitable intravenous formulations not
always available.
» Postoperative nausea and vomiting, or ileus will impact on absorption.
» Discuss with transplant centre.

Specific issues with certain drugs:
» Cyclosporin is nephrotoxic. Many antibiotics and amiodarone increase concentrations, therefore increasing the risk of renal damage.

Cyclosporin plus other nephrotoxins (NSAIDs, aminoglycosides) increases the risk of nephrotoxicity.

Chronic kidney disease impacts on
choice of drugs
(neuromuscular blocking agents, opioids).

> > Cyclosporin causes elevated blood pressure.

> > Tacrolimus and steroids are diabetogenic.

> > Steroids cause hypertension,
thinning of skin, raised BMI – all of which
have perioperative implications.

> > Steroid cover for major surgery may be necessary.

Susceptibility to infection:
» Strict asepsis, remove unnecessary
lines as soon as possible.

> > High index of suspicion of infection
in unusual sites with unusual organisms.

> > Prompt microbiological advice if infection suspected/discuss need for prophylaxis.

Question 3

c) What long-term health issues may occur in this type of patient? (20%)

Answer 3

> > Cardiac allograft vasculopathy.

> > Rejection causing reduction in graft function.

> > Chronic kidney disease due to immunosuppression.

> > Malignancy (squamous cell carcinoma, lymphoma)
due to immunosuppression.

> > Hypertension due to immunosuppression
and its consequent organ
damage, e.g. heart, kidneys.

> > Effects of systemic disease that
caused the need for transplant in the first
place (atherosclerosis, sarcoid, amyloid, diabetes).

> > Effects of diabetes caused by steroids or tacrolimus.