Transplant Flashcards
(33 cards)
By reading this article, you should be able to:
By reading this article, you should be able to:
- Describe the evaluation of potential heart transplant recipients.
- Discuss the management of primary graft dysfunction in the operating theatre and ICU.
- Identify the indications for initiating venoarterial extracorporeal membrane oxygenation.
- Explain the challenges faced by an anaesthetist at different stages of heart transplant surgery.
Key Points
- In selected patients, heart transplantation is the definitive treatment for acute or end-stage heart failure.
- Thorough preoperative evaluation by a multidisciplinary team is essential for optimal selection of patients and timing of heart transplantation.
- Primary graft dysfunction is the most important cause of
early death after heart transplantation. - Prolonged reperfusion of the donor heart is
critical for successful weaning from cardiopulmonary bypass
and avoiding primary graft dysfunction. - A low threshold should be used for initiating mechanical circulatory support, ideally extracorporeal membrane oxygenation, for treating graft dysfunction that is not responsive to moderate-dose inotropic drugs.
Conclusions
In this paper, we have reviewed the key issues faced by anaesthetists and intensivists caring for heart transplant recipients.
Perhaps the key point to emphasise is that when faced
with deteriorating LV or RV function
and escalating inotropic support,
early initiation of VA ECMO is essential—
and may be life-saving.
Given the number of patients awaiting heart transplantation
exceeds the supply of DBD donor organs,
it is likely there will be an increasing demand
for DCD organs over time,
further increasing the requirement for postoperative ECMO.
How many world wide
Most performed for
Waut time
Worldwide, there are approximately 5000 heart transplants annually.
In the year to February 2020, 174 adult heart transplants were performed in the UK, and there were 307 adult patients on the waiting list
Most heart transplants are performed for end-stage cardiomyopathy, either ischaemic or non-ischaemic
Patients classified as ‘non-urgent’,
the median wait time is about 4 yrs,
being shortest for blood group AB and longest for blood group O
How many world wide
Most performed for
Waut time
Worldwide, there are approximately 5000 heart transplants annually.
In the year to February 2020, 174 adult heart transplants were performed in the UK, and there were 307 adult patients on the waiting list
Most heart transplants are performed for end-stage cardiomyopathy, either ischaemic or non-ischaemic
Patients classified as ‘non-urgent’,
the median wait time is about 4 yrs,
being shortest for blood group AB and longest for blood group O
Median Survival
Death
Median survival after heart transplantation exceeds 12 yrs.3
Survival after heart transplantation is approximately twice that after lung transplantation
Early death is primary graft dysfunction (PGD);
the other main causes are infection and acute rejection
late death is cardiac allograft vasculopathy
(chronic rejection),
with other causes including
malignancy, infection and renal failure
Changes
Increased use of hearts from DCD donors 15%
is perhaps the most significant change in practice in heart transplantation medicine over the last 5 yrs
there is an increased requirement for postoperative mechanical circulatory support
Anaesthesia management for patients undergoing heart transplantation is demanding and frequently occurs on an emergency basis because of unpredictable availability of organs.
Assessment and management of common problems during heart transplantation.
Pretransplant assessment
- Increased PVR
Echocardiogram and right-heart catheter
If PVR >3 WU and limited reversibility,
consider inotropes, sildenafil and diuretics;
if not responsive, consider durable LVAD
- Impaired end-organ function
Renal and hepatic function tests
Consider a prolonged course of inotropes; if not responsive, consider durable LVAD
3.
Before surgery
ll patients Fragile cardiac status
Avoid giving sedative–hypnotic drugs in uncontrolled ward environment;
preserve right internal jugular vein for myocardial biopsy access; induce anaesthesia slowly with vasopressors to hand
- Patients with congenital heart disease or chronic indwelling CVCs
CT chest
May need alternative site of central venous access
3.Timing
Expected arrival of donor heart
Allow at least 1 h for anaesthesia and
1 h for preimplantation surgery; ensure native heart is not excised before the donor heart has been inspected by the surgeon
- Revision cardiac surgery
CT chest
Prepare for emergency CPB and blood transfusion
During surgery, before separating from CPB
- Haemodynamic instability
Haemodynamic monitoring and TOE;
discuss with surgeon,
as may be attributable to surgical manipulations.
Ask surgeon to briefly cease dissection;
augment preload and administer vasopressors;
if not successful, consider initiating CPB
- Reperfusion
TOE evaluation of donor heart
Allow at least 1 h for reperfusion with heart ejecting, but full CPB support; low-dose inotropic support and DOO pacing at 50–60 beats min
During surgery, after separating from CPB
- Haemodynamic instability
Haemodynamic monitoring and TOE
(including CI) to distinguish
between hypovolaemia,
vasoplegia and PGD
Augment preload based on TOE and CVP (CVP >15 mmHg unlikely to be beneficial);
inotropes and vasopressors to moderate doses;
avoid adrenaline (epinephrine) (or equivalent) >0.2 μg kg−1 min−1;
low threshold for initiating mechanical circulatory support,
ideally VA ECMO;
use iNO routinely to reduce PVR and minimise likelihood of PGD
- Bleeding
Platelet count, PT, aPTT, fibrinogen concentration and TEG
Administer blood component therapy based on test results;
for LVAD patients, consider desmopressin;
for warfarin reversal, consider prothrombin complex concentrate and vitamin K
Before surgery
Indications for heart transplantation
Heart transplantation may be considered in patients with
(i) Advanced heart failure with New York Heart Association Class III or IV functional status or recurrent hospitalisations despite maximal medical therapy
(ii)Recurrent life-threatening ventricular arrhythmias despite an implantable cardiac defibrillator (ICD)
(iii) Acute cardiogenic shock, requiring infusions of inotropic agents or temporary mechanical circulatory support
(iv) Refractory angina without further therapeutic options
Evaluation for heart transplantation
- multidisciplinary team at a regional transplant centre,
and they undergo a comprehensive
- physical, psychological and social evaluation.
Successful outcome from heart transplantation requires
strict adherence to complex
medical therapies together with the r
esilience to cope with unexpected setbacks.
- For ambulatory patients, scoring systems,
such as the Heart Failure Survival Score and the
Heart Failure Survival Score of medium to high risk
deemed potential transplant candidates
Seattle Heart Failure Model
- Cardiopulmonary exercise testing is also helpful, with a peak
V˙ o2 <12–14 mL kg−1 min−1 used as an indication for listing
Contraindications to heart transplantation
Absolute
- Advanced irreversible renal failure (creatinine clearance <30–50 mL min−1) without planned concurrent renal transplant
- Advanced irreversible liver disease without planned concurrent liver transplant
- Advanced irreversible lung parenchymal disease (FEV1 <1 L min−1)
- Advanced irreversible pulmonary hypertension (systolic pressure >60 mmHg; pulmonary vascular resistance >4–5 WU)
- Solid organ or haematological malignancy in the last 5 yrs
Contraindications to heart transplantation
Relative
Severe peripheral vascular disease
Severe cerebrovascular disease
Severe osteoporosis
BMI >35 kg m−2
Active infection (excluding LVAD-related infection)
Diabetes mellitus with end-organ damage
Psychological instability
Active or recent substance abuse (within 6 months)
Lack of social support
Pretransplant optimisation
- patients with cachexia—
defined as oedema-free body weight loss of more than 5% in 12 months—should be referred to a dietitian for nutritional support. - For patients with elevated PVR and limited reversibility, diuretics,
vasodilators, sildenafil and i.v. inotropes should be
given and the right-heart catheter study repeated
Assessment for anaesthesia
- presence of elevated PVR, RV dysfunction and renal impairment.
2.Congenital heart disease may have abnormal central veins, which might limit access sites for central venous access
- catheters (CVCs) may have thrombosed central veins.
- Previous cardiac surgery identifies an increased risk of bleeding.
- anticoagulated or have hepatic dysfunction and may need reversal agents or clotting factors before surgery
- LVAD, warfarin reversal should be performed in the operating theatre, at the time the device is explanted, to minimise the risk of intra-device thrombosis
- . Anti-tachycardia and defibrillation features of an ICD should be disabled before surgery.
Consent for anaesthesia should include the usual risks associated with cardiac surgery, such as blood transfusion and placement of a transoesophageal echocardiography (TOE) probe. Also, the anaesthetist should discuss the potential for postoperative ECMO, renal replacement therapy (RRT) and the risk of prolonged ICU stay and multiple organ failure.
Caution with sedatives on ward
During surgery
Routine anaesthesia managemen
In addition to standard monitoring,
a pulmonary artery catheter (PAC) and TOE are appropriate for all heart transplant recipients.
External defibrillator pads should be applied in all cases.
Large-bore i.v. access and an arterial catheter should be sited before inducing anaesthesia
Arterial catheterisation can be challenging in patients with LVADs because of non-pulsatile blood flow; ultrasound guidance is helpful. A CVC is usually sited after induction of anaesthesia, but may be done beforehand in very-high-risk recipients
septic technique, as the patient will be immunosuppressed postoperatively.
During surgery
Routine anaesthesia managemen
In addition to standard monitoring,
a pulmonary artery catheter (PAC) and TOE are appropriate for all heart transplant recipients.
External defibrillator pads should be applied in all cases.
Large-bore i.v. access and an arterial catheter should be sited before inducing anaesthesia
Arterial catheterisation can be challenging in patients with LVADs because of non-pulsatile blood flow; ultrasound guidance is helpful. A CVC is usually sited after induction of anaesthesia, but may be done beforehand in very-high-risk recipients
septic technique, as the patient will be immunosuppressed postoperatively.
Particulars
he CVC and PAC should be sited in the left internal jugular vein, as the right vein is reserved for subsequent myocardial biopsy. To avoid interference in the surgical field, the PAC should not be advanced into the pulmonary artery until after implantation of the graft.
considered extremely fragile and prone to excessive hypotension in response to standard doses of sedative and opioid drugs
iven slowly, allowing adequate time to determine their peak haemodynamic and hypnotic effects, which may be prolonged because of low cardiac output.
Vasopressor drugs for treating hypotension should be drawn up beforehand. Hypoxia and hypercarbia should be avoided to prevent abrupt increases in PVR, which can precipitate acute RV failure
Abx + Immunosuprresions
Antimicrobial and immunosuppressive drugs are given after induction of anaesthesia according to institutional protocol.
I.V. methylprednisolone is usually given at induction and again after reperfusion of the graft.
y. An antifibrinolytic drug such as tranexamic acid should be given to reduce bleeding and transfusion requirements.
Surgical considerations
CPB, i.v. heparin is given at a standard dose (350–450 U kg−1), targeting an activated clotting time above 400–500 s.
Repeat heparin dosing or antithrombin III concentrate (500 U) may be required in patients who have heparin resistance
Nowadays, heart transplantation is typically performed using a bicaval technique, whereby the entire native right atrium (RA) is excised and the donor SVC, IVC, aorta and pulmonary artery are individually anastomosed to the respective recipient vessels.
cuff of native LA containing the four pulmonary veins is anastomosed to the donor LA. The bicaval approach is associated with reduced mortality and a lower incidence of postoperative complications—notably, a reduced likelihood of permanent atrioventricular block—compared with the classical biatrial technique
Management before allograft implantation
Detailed TOE evaluation of the native heart is not required. However, the anaesthetist should alert the surgeon to the presence of intra-cardiac thrombus, aortic atheroma and pleural effusions, which may require the surgeon to alter the cannulation technique. Pleural effusions should be drained
Preparation for separating from CPB
During graft implantation, the anaesthetist should prepare for separating from CPB. Important considerations include the potential need for pacing, haemodynamic support and blood component therapy. The temporary pacemaker should be checked and infusions of inotropic, pulmonary vasodilator and anti-arrhythmic agents prepared.
Initially, a combination of DOO pacing (90–110 beats min−1) and low-dose dopamine (3–5 μg kg−1 min−1) or dobutamine (3–5 μg kg−1 min−1) is a reasonable strategy.
milrinone (0.25–0.5 μg kg−1 min−1) or enoximone as an inotrope and pulmonary vasodilato
Inhaled nitric oxide (iNO) at 10–20 ppm can be used as a pulmonary vasodilator and to attenuate PGD
