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Transplantation and Thromboendarterectomy
for Severe Pulmonary Hypertension: Report from the Transplant
and Interventions Task Force
Paul A Corris, MB, FRCP
Newcastle University and Regional Cardiothoracic Center
Newcastle Upon Tyne, United Kingdom
Recent advances in medical and interventional approaches
to the management of patients with pulmonary arterial
hypertension (PAH) have had a marked effect on the policy
toward referring such patients for transplantation and
there has been a reduction of 50% in numbers of patients
with primary pulmonary hypertension (PPH) undergoing transplantation
over the last decade.1 In
practice patients are being referred at a later stage,
often in decompensated right heart failure. Such patients
present a major challenge to both peri- and postoperative
management, with some centers identifying the need for
elective ECMO support or at least prolonged ventilatory
support. The prognosis of patients presenting with WHO
class III and IV symptoms has been improved by both prostaglandin
and endothelial antagonist therapy.2-6
But not all patients show a significant response, so the
concept of assessing a patient with advanced disease,
listing when appropriate and de-listing if there was a
significant response to medical therapy such that the
patient improved to WHO class II on symptoms, was supported.
The literature supports that transplant centers currently
show wide variation in their approach to indications for
and timing of lists. It is clear that close communication
between PAH centers and transplantation centers is very
appropriate.
The results of transplantation for patients with severe
pulmonary hypertension (PH) as documented in the International
Society for Heart and Lung Transplantation registry data
are significantly less good than for patients with respiratory
failure due to other causes. It was concluded that transplantation
for patients with PH might be best limited to specialist
transplant centers with specific interests and skills
in treating such patients, rather than being offered by
a transplant center, and that such an approach might best
fulfill the needs of our patients. It was recognized that
the problem of donor lung shortage had led to the need
to use marginal lungs from older donors, and that this
practice was a particular risk for patients with pulmonary
vascular disease.
No true consensus was established with regard to the
operation of choice for patients with PH. There was a
broad body of literature supporting single lung, bilateral
lung, and heart-lung procedures for these patients.7-10
It was accepted that patients with Eisenmenger syndrome
associated with complex congenital heart disease could
not be repaired during an isolated lung transplantation
procedure and required heart-lung transplantation. There
was a trend to supporting the concept of transplanting
two lungs rather than one in patients with advanced disease
with established right heart failure. However, it was
accepted that specialist centers would carry out whichever
type of operation they felt was most appropriate for an
individual case. It was also accepted that individual
differences would occur given differences in thoracic
organ allocation and availability.
The recent UNOS guidelines relating to organ allocation
to patients with PH in the United States were discussed
and it was felt that the proposed walking distance of
160 feet as an arbiter of clinical need and benefit regarding
transplantation was too low and incompatible with satisfactory
outcomes.
It was recognized that the development in molecular biology
offered unrivaled opportunity to help understand underlying
mechanisms leading to PPH and associated conditions and
that lungs removed at transplantation offered an important
resource for research. It was proposed that attempts should
be made to ensure that all lungs removed at surgery should
be stored in tissue banks and made available to the many
individual laboratories worldwide to foster basic research
in this area. It was regrettable that lungs from patients
transplanted for PH were not systematically being stored.
Finally, brief guidelines regarding referral and listing
are summarized below.
- WHO class III patients with 6-minute walk distance
>332 meters: Treat medically and refer for transplant
if no clinical improvement over 3 months.11
- WHO class IV patients with 6-minute walk distance
<352 meters: Assess and list immediately for transplantation,
treat medically, and de-list if improvement over 3 months
to class II. Deteriorating patients may be considered
for septostomy as a bridge to transplantation.
- Hemodynamic markers of adverse outcome are right atrial
pressure >15 mm Hg, cardiac index <2 L/min/m2, and mixed
venous oxygen saturation of =63%.
Thromboendarterectomy
There was a clear consensus that patients with PH due
to chronic thromboembolic disease should be assessed for
thromboendarterectomy and it was proposed that the name
of this operation should be changed to pulmonary endarterectomy.12-14
This suggestion was made because by the time of surgery
no true thrombus remained. It was recognized that more
experienced centers worldwide were carrying out successful
surgery in patients with severe distal disease as well
as proximal disease, a technically more challenging procedure.15
Discussion concerned the presence of vasculopathy similar
to that seen in PPH in the vessels of patients with chronic
thromboembolic hypertension unaffected by previous thrombi.
Mechanisms leading to this vasculopathy are not understood
at present but it did provide a rationale for consideration
of medical therapy with prostaglandins and endothelial
antagonists in some patients prior to definitive surgery.16
The worldwide results of thromboendarterectomy are good,
and prognosis and health-related quality of life in such
patients are much improved by this operation. 14
References
1. Hertz M, Taylor D, Trulock E, et al.
The Registry of the International Society for Heart and
Lung Transplantation: nineteenth official report – 2002.
J Heart Lung Transplant. 2002;21:950-970.
2 Barst RJ, Rubin LJ, Long WA, et al.
A comparison of continuous intravenous epoprostenol (prostacyclin)
with conventional therapy for primary pulmonary hypertension.
N Engl J Med. 1996;334:296-301.
3. Simonneau G, Barst RJ, Galie N, et al. Continuous subcutaneous
infusion of treprostinil, a prostacyclin analogue, in
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JD. Single-lung transplantation for pulmonary hypertension:
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Am J Respir Crit Care Med. 1999; 160:523-528.
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Cardiovasc Surg. 2002;124:1203-1211 15. Olschewski H,
Simonneau G, Galie N, et al. Inhaled inoprost for severe
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