NHLBI Working Group
Disease of the Thoroco-Abdominal Aorta (TAA)
The National Heart, Lung, and Blood Institute convened a Working Group
on September 19, 2005, in Bethesda, Maryland to identify clinical research
opportunities and critical gaps in our knowledge about thoraco-abdominal
aortic diseases in order to facilitate clinical detection and treatment
of these diseases. The major objectives were to: (1) review the current
state of basic research of thoraco-abdominal aortic diseases as it applies
to future clinical applications; (2) identify basic science findings that
are ready for translation into clinical research; (3) foster exchange
of novel ideas to promote improved understanding of the temporal structural
and mechanical changes that relate to disease progression of the thoraco-abdominal
aorta; (4) identify research opportunities to improve clinical decision-making
and health care delivery in order to optimize patient outcomes:, and (5)
provide a prioritized set of novel research recommendations to the NHLBI
that will direct its future research agenda and ultimately improve the
diagnosis and treatment of diseases of the thoraco-abdominal aorta.
The Working Group members reviewed recent findings in basic research,
clinical diagnosis, and treatment strategies related to diseases of the
TAA. The discussion focused on the need for an improved understanding
of the natural history of TAA diseases. There are few, if any, animal
models of TAA disease. The Working Group thought that reliable animal
models should be developed that replicate the etiology and pathogenesis
of TAA diseases in humans. Members agreed that research using relevant
animal models is an important intermediate step in the translation of
results from basic science into clinical trials. In addition, the group
stated that human TAA tissue must be collected and studied to evaluate
gene and protein expression and elucidate histologic, biochemical, mechanical,
and structural properties of TAA diseases.
The Working Group identified inadequate phenotyping in existing patient
registries as a critical gap area. Full spectrum phenotyping was considered
essential to advancing knowledge, and should include a comprehensive patient
and family history and physical examination, as well as serial imaging
studies such as echocardiograms, computerized tomography, and dynamic
magnetic resonance imaging. The use of imaging to study the biomechanics
of aneurysmal wall stress in the diseased TAA was also an area of interest.
Important gaps in our understanding of diseases of the TAA include: the
potential benefits of endovascular repair of type B aortic dissection
compared to optimal medical therapy; the benefits and risks of endovascular
compared with surgical repair of TAA aneurysms; and the effects of medical
therapies such as beta adrenergic blockers, angiotensin converting enzyme
inhibitors, or angiotensin receptor blockers on expansion and outcome
of aneurysms of the TAA. Randomized clinical trials were considered important
mechanisms to develop new therapies for diseases of the TAA.
Understanding mechanisms of neurologic injury and spinal cord protection,
in both surgical and endovascular repair, are needed to improve pharmacologic,
endovascular and surgical treatment strategies in order to prevent paraplegia
- Support investigations of the natural history of diseases of the
TAA, including extensive phenotyping of registry participants, as well
as tissue collection for both genomic/proteomic investigation and for
examination of tissue characteristics/orientation.
- Support a large multicenter clinical trial to compare optimal medical
therapy to endovascular repair in acute uncomplicated type B dissection.
- Support investigations into the mechanisms of neurologic injury to
the spinal cord during operations on the thoraco-abdominal aorta and
explore techniques for spinal cord protection in the setting of both
surgical and endovascular repair.
- Support a randomized clinical trial to compare optimal medical therapy,
open surgical repair, or endovascular repair for the management of aneurysms
of the TAA.
- Support a randomized clinical trial to identify optimal medical therapy
for the treatment of small aneurysms of the TAA, early manifestations
of aortic disease in susceptible individuals such as those with Marfan
syndrome, and any aneurysm in non-surgical candidates. Optimal medical
therapy could include beta adrenergic blockers, angiotensin receptor
blockers or angiotensin converting enzyme inhibitors alone or in combination.
- Support the development of small animal models of thoracic and thoraco-abdominal
A summary of the workshop proceedings and recommendations will also be
published in a peer-reviewed scientific journal. Anticipated publication
date is 2006.
Suzanne Goldberg, R.N., M.S.N., NHLBI, NIH
Last updated: October 28, 2005