Postoperative Care of the Heart and Lung Transplant Patient

Key Points

1.
The care of heart and lung transplant patients requires a multidisciplinary approach by a team dedicated to collaborating to provide the best care.
2.
Inotropic therapy is often required for patients undergoing heart or lung transplantation with lung transplant patients primarily requiring right heart support.
3.
Atrial fibrillation impacts both heart and lung transplant patients.
4.
Immunosuppression must be carefully monitored by the multidisciplinary team and a high index of suspicion for graft dysfunction should be maintained in patients that do not progress as anticipated.
5.
Infectious complications are of concern for both heart and lung transplant patients; however, due to higher immunosuppression requirements and risk for preexisting infections in either the donor or recipient, lung transplant patients are at particular risk for severe infection.
6.
Unique issues impacting lung transplant patients include airway obstruction, aerodigestive tract dysfunction, and hyperammonemia.

Heart and lung transplant surgery continues to be the gold standard for the treatment of end-stage heart and lung disease. These surgeries are complicated by unique problems in the postoperative period, particularly due to the side effects of immunosuppression. A thorough understanding of the unique physiology and pathology of these patients is crucial for the cardiovascular anesthesiologist and surgical intensivist.

Postoperative Heart Transplant Management

Arrhythmias

Cardiac arrhythmias are common in the postoperative period following heart transplantation (HT). Resting normal sinus rhythm in the new denervated heart is commonly above 80 beats/min (bpm) with rates going as high as the low 100s bpm. This increase in the baseline is caused by a loss of parasympathetic tone due to the absence of vagal neural input. Restoration of baseline heart rate is not expected for up to 96 months after transplant.

Sinus node dysfunction occurs in up to 50% of patients following HT with relative sinus bradycardia being the most common manifestation. ^, It is important to note that some traditional treatments such as atropine are not effective in treating bradycardia in HT patients given the absence of vagal innervation in the postoperative period. Sympathomimetics such as isoproterenol or terbutaline may be used as an emergency treatment of symptomatic bradycardia for patients who do not have pacemaker wires in place. Finally, up to 25% of HT patients will require implantation of a permanent pacemaker.

The most common conduction abnormality is a new right bundle branch block (RBBB) occurring in up to 70% of patients. ^, High-grade atrioventricular (AV) block is uncommon, particularly in the early postoperative period.

Supraventricular Arrhythmias

Atrial Fibrillation or Atrial Flutter

Atrial fibrillation (AF) and flutter is common in the immediate postoperative period with the incidence reported as 10% to 25% for AF and 12% to 15% for flutter. Late occurrence AF can be associated with graft rejection. Treatment of these arrhythmias is similar to other settings (see Chapter 24, Chapter 8 ). Anticoagulation in the early phase after HT is problematic due to frequent endomyocardial biopsies.

Supraventricular Tachycardias

There are a variety of supraventricular arrhythmias that can occur following HT including AV reentrant tachycardia involving a concealed AV bypass tract, Wolff-Parkinson-White syndrome, and sustained atrial tachycardias. Most of these arrhythmias come with the transplanted heart, even if the donor never experienced such rhythms. Radiofrequency catheter ablation has been performed in many of these patients with success and complication rates similar to other patient populations (see Chapter 24 ).

Ventricular Arrhythmias and Sudden Cardiac Death

Nonsustained ventricular tachycardia (VT) is relatively common in the early posttransplant period. In most cases, the arrhythmias do not correlate with rejection or graft failure, and their frequency decreases over time. Nonsustained VT occurring late after transplantation should raise suspicion for severe cardiac allograft vasculopathy (CAV) or allograft rejection, and internal cardioverter-defibrillator (ICD) placement may be considered (see Chapter 3 ). Unfortunately, up to 25% of these patients may develop sudden cardiac death (SCD). Acute ischemia is the most common etiology followed by rejection and severe left ventricular (LV) dysfunction. Additionally, in a large retrospective analysis, terminal rhythms in patients with SCD were shown to be asystole in 34%, pulseless electrical activity in 20%, and ventricular fibrillation (VF) in 10% of cases.

Induction and Maintenance of Immunosuppression

The optimal goal of immunosuppression is to prevent immune-mediated graft rejection, while minimizing toxicity and major sequelae of such therapy. Clinically relevant complications include infection, renal dysfunction, hypertension, glucose intolerance, and malignancy. The different drugs and their side effects are shown in Table 36.1 .

TABLE 36.1

Clinically Relevant Side Effects of Transplant Immunosuppression Medications ^a

Medication	Common	Uncommon
Induction Agents
Antithymocyte globulin	Lymphopenia Thrombocytopenia Infusion-related reaction	Systemic inflammatory response syndrome
Alemtuzumab	Lymphopenia Thrombocytopenia Infusion-related reaction	Thyroid disorders Immune thrombocytopenia Glomerulonephritis
Basiliximab		Infusion-related reaction
Corticosteroids	See below	See below
Maintenance Agents
Calcineurin inhibitors (class effects)	Nephrotoxicity Hypomagnesemia Hyperkalemia Tremor Headache	Posterior reversible encephalopathy syndrome Microangiopathic hemolytic anemia Calcineurin inhibitor–induced pain syndrome Neuropathy
Tacrolimus	Hyperglycemia Alopecia	Chronic leukoencephalopathy
Cyclosporine	Hypertension Hirsutism	Gingival hyperplasia
Mammalian target of rapamycin inhibitors (class effects)	Dyslipidemia Hypertension Peripheral edema Delayed wound healing	Surgical site dehiscence Leukopenia Pneumonitis Stomatitis
Antimetabolites (class effects)	Leukopenia Anemia Thrombocytopenia	Teratogenicity
Azathioprine	Transaminitis	Pancreatitis Cutaneous hypersensitivity syndrome
Mycophenolate mofetil	Nausea Diarrhea	Headache
Corticosteroids	Hyperglycemia Hypertension Skin thinning Muscle weakness	Psychosis Avascular necrosis Cataracts Osteoporosis
Belatacept	Hypotension	Infusion-related reaction

a As immunosuppressive agents, all therapies on this table are associated with increased risk of infection and most are associated with increased risk of malignancy.

Immunosuppression consists of two phases: induction and maintenance. The induction phase refers to the initiation of intense immunosuppression in the immediate perioperative period, while the risk of allograft rejection is the highest. Polyclonal antithymocyte globulin (ATG) is commonly used in this phase, and while different preparations for ATG exist, all utilize polyclonal antibodies against multiple human antigens expressed on T-lymphocytes to attenuate their response. Interleukin-2 receptor antagonists (IL-2Ra) are another group of commonly used agents that bind IL-2 receptors on activated T-cells preventing T-cell proliferation and attenuating the graft-directed immune response.

The maintenance phase of immunosuppression is generally initiated within the first several days following HT. This multidrug therapy commonly consists of a calcineurin inhibitor (CNI), cell cycle inhibitor, and corticosteroid. CNIs are considered one of the core immunosuppression agents that work by targeting calcineurin, a key enzyme in the production pathway of multiple cytokines including IL-2. This subsequently inhibits the expansion of CD4+ and CD8+ cell lines. Mycophenolate mofetil is another common cell cycle inhibitor used for maintaining immunosuppression. Mycophenolate is a noncompetitive inhibitor of inosine monophosphate dehydrogenase, a key enzyme in guanine nucleotide production selectively blocking lymphocyte proliferation. Finally, corticosteroids play a key role in both the induction and maintenance of immunosuppression. Steroids exhibit broad and nonspecific effects and inhibit several transcription factors involved in the production of cytokines, tumor necrosis factor-alpha (TNF-alpha), and many growth factors to interfere with the function of white blood cells.

Graft Dysfunction

Function of the newly transplanted heart is affected by a multitude of factors including donor, recipient, and surgical factors. Graft dysfunction can occur as early as intraoperatively or may develop years after transplantation, and the timing of dysfunction usually offers the best clue to the underlying diagnosis. Graft failure may also manifest itself in various ways, presenting as left, right, or biventricular dysfunction, and portends significant morbidity and mortality.

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