Abstract
The first successful human-to-human heart transplant was performed by Christiaan Barnard in 1967 but the initial outcomes were poor. The introduction of ciclosporin resulted in a significant improvement in survival, leading to an increase in heart transplantation through the 1980s. A total of 5,149 heart transplants, including 4,547 adult transplants, were performed at 302 transplant centres worldwide in the year to July 2017, with 86% 1-year survival, just over 50% survival at 10 years and a median survival of 11 years.
The first successful human-to-human heart transplant was performed by Christiaan Barnard in 1967 but the initial outcomes were poor. The introduction of ciclosporin resulted in a significant improvement in survival, leading to an increase in heart transplantation through the 1980s. A total of 5,149 heart transplants, including 4,547 adult transplants, were performed at 302 transplant centres worldwide in the year to July 2017, with 86% 1-year survival, just over 50% survival at 10 years and a median survival of 11 years.
In the last few years, transplantation after donation after circulatory-determined death (DCD) has been investigated as an additive alternative to donation after brain death (DBD). Adoption of this technique may increase the number of donor organs by more than 20%. Initial studies suggest that 2-year survival after DCD transplantation is the same as DBD transplantation.
Indications
Heart transplantation remains the definitive treatment for end-stage heart failure with impaired LV systolic function and NYHA class 3–4 symptoms despite optimal medical, device and surgical treatment. The aetiology of end-stage heart failure leading to heart transplantation are summarized in Box 17.1.
Box 17.1 Aetiology of heart failure in adult heart transplant recipients
Cardiomyopathy – predominantly dilated cardiomyopathy (56%)
IHD (35%)
Valvular heart disease (3%)
Adult congenital heart disease (3%)
Re-transplant for graft failure (3%)
Other less common indications for transplantation include:
Persistent ventricular arrhythmias, refractory to standard therapies
Refractory debilitating angina, unresponsive to conventional therapy
Restrictive cardiomyopathy
Hypertrophic cardiomyopathy
Arrhythmogenic right ventricular cardiomyopathy
Peripartum cardiomyopathy
Acute myocarditis
Contraindications
The timing of patient evaluation for heart transplantation is of key importance. Patients should be referred before irreversible complications occur, as these may complicate or contraindicate transplantation (Box 17.2).
Box 17.2 Indications for referral for heart transplantation evaluation
RV failure or increasing PAP on optimal treatment
Deteriorating renal function attributable to heart failure
Persistent heart failure and/or increasing brain natriuretic peptide on optimal medical treatment
Two or more admissions within 12 months for treatment of decompensated heart failure
Significant ventricular arrhythmias despite optimal medical, electrophysiology and device therapy
Seattle Heart Failure Model (SHFM*) score indicating ≥20% 1-year mortality
Liver dysfunction, hyponatraemia, anaemia or involuntary weight loss attributable to heart failure
Indications for urgent inpatient referral:
Requirement for continuous inotrope infusion and/or IABP
Persisting coronary ischaemia
Persistent circulatory shock as a result of a primary cardiac disorder
Contraindications to heart transplantation include conditions that would significantly increase morbidity or mortality after transplantation, shorten life-expectancy, complicate postoperative recovery or preclude long-term compliance with immunosuppression (Box 17.3).
Allosensitization – anti-human leucocyte antigen antibodies
Severe irreversible PHT
Age >70 years (transplant unlikely >65 years in UK)
Obesity: BMI >35 kg m–2
DM with end-organ damage or poor glycaemic control
Severe renal dysfunction (estimated GFR <30 ml min–1 per 1.73 m2)
Active malignancy or a history of malignancy with probability of recurrence
Severe cerebrovascular disease
Severe peripheral vascular disease
Advanced liver or lung disease
Recent PE
Infection (sepsis and active infections)
Frailty
Active substance abuse
Severe cognitive-behavioural disabilities, dementia, insufficient social supports or other demonstrated inability to comply with instructions and drug therapy
Mechanical ventilation
Autoimmune disorders
Infiltrative cardiac diseases
Severe skeletal myopathies
Organ dysfunction may occur as a result of severe heart failure and may be potentially reversible with medical therapy or the use of mechanical circulatory support (MCS) as a bridge to transplantation. PHT secondary to pulmonary venous congestion is common in heart-transplant recipients and is associated with RV dysfunction and increased mortality. A TPG above 15 mmHg and a PVR above 5 Wood units (400 dyne s cm–5) is associated with a significant increase in mortality and is therefore a contraindication to heart transplantation.
Anaesthesia for Heart Transplantation
Heart transplantation presents significant anaesthetic challenges. Patients in end-stage heart failure typically have both systolic and diastolic dysfunction manifested by a low CO (SV), elevated ventricular end-diastolic volume and pressure, and pulmonary and hepatic venous congestion. Levels of circulating catecholamines are elevated, leading to down-regulation of adrenergic receptors, diminished myocardial catecholamine stores and reduced sensitivity to inotropes. The failing heart is preload-dependent and afterload-sensitive – minor changes in the SVR, CVP, HR, heart rhythm and cardiac contractility are poorly tolerated. In addition, heart failure alters the pharmacodynamics and pharmacokinetics of many anaesthetic drugs. The anaesthetist should anticipate these changes to avoid excessive myocardial depression and changes in vascular resistance.
The functional status of patients ranges from the ambulatory outpatient to the obtunded critically ill patient on multiple IV inotropes, an IABP and MCS. As a consequence of the shortage of donor organs, around half of recipients are bridged with MCS.
Heart transplantation is generally considered to be an urgent or emergent procedure, as delays to organ implantation increase the ischaemic time and the risk of ischaemia-reperfusion injury. Minimizing the delay requires close communication between the donor harvest and implantation teams.
With the exception of the most urgent cases, the majority of recipients will have already undergone extensive assessment, investigation and preparation. Nevertheless, a rapid yet thorough preoperative assessment should be undertaken; focusing on current symptoms and functional status, current medication (including anticoagulation and antiplatelet therapy), the current level of cardiovascular support, fasting status and airway evaluation. Recent laboratory investigations, imaging, pulmonary function tests and right heart catheter studies should be reviewed to exclude any recent deterioration.
The timing of implant surgery and organ procurement will have to take into account any factors that might prolong recipient preparation, for example previous cardiac surgery. A modified rapid sequence induction may be indicated as patients are often inadequately fasted.
Recipients often have an implanted rhythm management device that will be removed at the end of surgery. These should be interrogated, and therapies deactivated prior to the induction of anaesthesia.
A suitable quantity of cross-matched blood and blood products should be immediately available. These should be leucocyte-depleted and should be cytomegalovirus (CMV) negative if both the donor and recipient are CMV negative.
Vascular Access and Monitoring
Standard AAGBI-recommended monitoring should be used along with core temperature and urine output. These patients will also require invasive pressure monitoring (MAP, CVP, PAP), a means of measuring the CO and TOE to monitor cardiac function. Depth of anaesthesia monitoring and cerebral oximetry may be useful.
Large-bore peripheral IV access and invasive arterial monitoring is the minimum requirement prior to the induction of anaesthesia. Depending on the preoperative condition of the patient, central venous access may also be considered prior to induction. All patients undergoing heart transplantation require the insertion of a multi-lumen central venous catheter and a central venous sheath for rapid infusion of fluid and insertion of the PA catheter. It is important to withdraw the PA catheter from the right heart prior to CPB. Central venous access can be challenging in these patients as insertion sites may have been used repeatedly and there may be a degree of anticoagulation. Strict adherence to sterile technique is critical, due to immunosuppression therapy and increased infection risk.
Induction and Maintenance of Anaesthesia
The goal is maintenance of haemodynamic stability and vital organ perfusion until the institution of CPB.
Induction may be challenging, as anaesthetic drug-induced suppression of sympathetic tone produces vasodilatation and myocardial depression, which untreated may rapidly progress to haemodynamic decompensation and cardiovascular collapse. The choice of anaesthetic drugs is far less important than the manner in which they are administed. Pre-emptive inotropic and vasoconstrictor support (or an escalation of the existing therapy) may be required to offset the deleterious effects of anaesthesia and positive pressure ventilation.
In addition to providing information about cardiac anatomy and function, TOE allows the assessment of cardiac filling, the severity of PHT and the presence of intracardiac thrombus, significant aortic atheroma and pleural effusions.
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