Comment
Valuable advances have been made in understanding the risk factors and
mechanisms responsible for the development of PAH in thalassemic
patients. It is now known that chronic hemolysis with the resulting
nitric oxide depletion can lead to endothelial dysfunction and vascular
remodeling and, in due course, to PAH [1]. Additionally, vascular
thromboembolic occlusions can also develop due to in situthrombosis as well as to pulmonary thromboembolism attributable to the
well-recognized hypercoagulable state [2]. The relative contribution
of hemolysis-related vasculopathy versus pulmonary thromboembolism in
the development of PAH in a specific patient depends on the severity of
the genetic defect and the provided treatment methods (such as
transfusion rates, chelation therapy and splenectomy) [1]. This
needs to be evaluated in every case individually employing a detailed
and systematic analysis of lung perfusion [6].
Conventional management approaches to PAH in thalassemic patients
include hemoglobinopathy-targeted therapy, PAH-specific medications as
well as general supportive treatment. Existing evidence indicates that
currently available drug therapies only temporarily and sporadically
improve symptoms in CTEPH, and remain ineffective in ameliorating the
mechanical obstructions of the pulmonary arteries or in improving
patients’ survival [7]. In this context, given that PTE has been
established as the gold-standard therapy for CTEPH, it is conceivable
that PTE may comprise the only potentially curative therapy for CTEPH in
thalassemic patients.
Experience to date with PTE in thalassemic patients with CTEPH is
limited to small series or isolated case reports, nevertheless these
reports favor PTE as an effective treatment of surgically accessible
CTEPH [3, 4]. We reported here the successful performance of PTE
surgery in a thalassemic patient with CTEPH irresponsive medical
treatment. Pre-operative assessment indicated that this patient was an
appropriate candidate for PTE despite a slightly increased potential
surgical risk owing to the underlying thalassemia. The post-operative
course was relatively uneventful, and was coupled with an early
substantial improvement in hemodynamics and functional status.
It is notable that the post-operative reduction in PAP in our patient
was less than that commonly expected following PTE [3] which is
likely to be due to the multifactorial nature of PAH in thalassemia. In
fact, concern remains that the chronic hemolysis-related vasculopathy in
the distal vessels may place thalassemic patients at increased risk of
residual or recurrent PAH after PTE [4]. Therefore, long-term
results of PTE in thalassemic patients remains to be elucidated through
long-term follow-up. It is noteworthy here that balloon pulmonary
angioplasty has recently been proposed as a potential new therapeutic
option for this process [8].
In conclusion, this case report supports the feasibility of PTE in
thalassemic patients with surgically accessible CTEPH. Given the
complexity of the pathophysiology of PAH in thalassemia, a comprehensive
evaluation for both the presence and cause of PAH is imperative prior to
determining the likelihood of surgical cure in each individual patient.