Gastrointestinal most commonly identified in individuals of advanced age

Gastrointestinal angiodysplasia(GIAD)
is a relatively rare medical condition with acquired vascular abnormality of
the superficial layers of the walls of the digestive tract. GIADs are most
commonly identified in individuals of advanced age above 60years old. They
manifest as flat or slightly elevated lesions of the surface of intestinal
mucosa, round or with irregular contour, of red color and most often of
diameter 2-10mm. GIAD may be located anywhere in the gastrointestinal tract,
but have been most  identified in the
colon.

Various theories have been postulated
regarding the etiology and pathophysiology of the condition, but there is still
not a general consensus about a unique mechanism of the disease. However, GIAD
is accepted as a degenerative disease of elderly. The disease can exhibit
various  clinical presentation,including asymptomatic,
overt or occult gastrointestinal bleeding, and iron deficiency anemia. Over the
past decades, GIAD has been found to be associated with aortic stenosis(AS),
chronic renal disease, hepatic cirrhosis and Von Willebrand’s disease(VWD) in
some particular cases.

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Eosophagogastroduodenoscopy(EGD) and
colonoscopy are the gold-standard endoscopic techniques for diagnostic
evaluation of GIADs. They both offer diagnostic and therapeutic possibilities
during the procedure. EGD and colonic endoscopy may however give negative
results, and in the face of obscure gastrointestinal bleeding(OGIB), endoscopy
of the small intestine should be considered. Endoscopic techniques of small
bowel comprise Video capsule endoscopy (VCE), push enteroscopy (PE) and  device assisted enteroscopy (DAE). In cases
with intractable active gastrointestinal hemorrhage, imaging techniques are
usually helpful. These include radionuclide scanning, catheter angiography,
computed tomography angiography (CTA), computed tomography enterography (CTE)
and magnetic resonance enterography (MRE).

The therapy of gastrointestinal
angiodysplasia is individualized. Endoscopic therapeutic techniques are most
commonly valued and argon plasma coagulation (APC) is the prevailing treatment
modality. Endoscopic therapy encloses other techniques like electrocautery
probes, endoclips which have shown some efficacy in selected cases of GIADs.
Where endoscopic therapy is limited, pharmacological treatment has been tried,
with unsatisfactory results. Several studies have showed that somatostatin
analogues may be beneficial in prevention of recurrent bleeding from GIADs.
Currently under study, thalidomide already holds promise for pharmacological
therapy of resistant cases of bleeding GIADs. 
Some cases of GIADs present with severe hemorrhagic manifestation and
hemodynamic instability which do not resolve with conventional therapy. Such
cases are candidates for transcatheter embolization or surgical interventions.

This review summarizes the
epidemiology, postulated etiopathogenesis, clinical, diagnostic and therapeutic
aspects of GIADs , with emphasis on colonic angiodysplasia. The diagnostic work
up and therapeutic measures include the most recent advances and forthcoming
prospects.

 

INTRODUCTION

1.     
Nomenclature

The word
“angiodysplasia” comes from the Greek word “angeion” meaning “tube/vessel”,
“dys” for “abnormal” and “plasis” for “form/shape”, therefore angiodysplasia
would mean abnormal vessel formation. Gastrointestinal angiodysplasias are
aberrancy of the blood vessels (veins, arteries and capillaries) which supply
the mucosal lining of the gastrointestinal tract. The first case of GIAD was
depicted in literature in early 18391. The term gastrointestinal
angiodysplasia was first prompted by Galdabini in 19742. GIAD referred to single or multiple
acquired lesions of the blood vessels of the mucosal and/or sub mucosal layer
of the gastrointestinal tract, which were not associated to dermatologic or
visceral angiomata 2, 3. However, there has been a lot of
controversy in past and present literature about the definition and
nomenclature of gastrointestinal vascular abnormalities. Various terms have
been used interchangeably to refer to the GIADs, namely angioectesia4-6, arteriovenous malformation4, 7-9, telangiectasia5, 10 ,vascular ectasia11,vascular malformation12, 13, angioma14 and hemangioma15, 16. Presently, the terminologies of
angiodysplasia, vascular ectasia, angioectesia, and vascular malformation are
the most commonly used in literature to refer to the concerned pathology.

2.     
Description

The characteristic appearance a
gastrointestinal angiodysplastic lesion may be defined endoscopically or by
analysis of histological specimen. At endoscopy, a typical GIAD lesion appears
as a cherry-red, small, 2-10mm diameter, of circular shape, flat or slightly
elevated lesion of the mucosal surface 17, 18. The margins of the GIAD are usually
irregular adopting a fern-like appearance due to presence of prominent vessels
radiating from the lesion. (Figure 1).

 

Figure 1: Colonoscopy image showing
aberrant ectatic vessels(arrows) of colonic mucosa

Microscopic examination of
histological specimens of GIAD demonstrates the distension of veins of the sub
mucosa, and the dilation of venules and capillaries of the mucosal layer 4. The abnormal distorted vessels of
GIAD are dysmorphic, contain minimal of no smooth muscle within their walls and
are lined only by thin endothelial layer19

3.     
Classification

There has been several proposed system
of classification of gastrointestinal vascular abnormities, without a single
one prevailing over the others 9, 13, 20-23.

Cappell and colleagues have proposed
a classification of vascular anomalies of digestive tract which has been
adopted by many. It groups the vascular lesions into two major categories,
namely neoplastic vascular lesions and non-neoplastic lesions, based on the
pathophysiology and anatomical features. Examples of neoplastic vascular
lesions are angiosarcomas, angiomas,and haemangioendotheliomas ,among others.
The non-neoplastic group comprised the sub categories: Inflammatory lesions,
Obstructive lesions and structural abnormalities. The latter comprises venous,
capillary, arteriovenous and arterial alterations24. 
The classification system of GI vascular anomalies, based on anatomy and
pathophysiology is shown in table 1, with examples for each category. It should
be noted that GIAD is categorized under non-neoplastic vascular lesions  involving structural alterations of  the arteriovenous system.

 

Table 1: Proposed
classification of gastrointestinal vascular abnormalities by Cappell and al.

Gastrointestinal vascular
abnormalities

Examples:
hemangioma, angiosarcomas

One of the
reasons prompted to be behind the non-ratification of a unique classification
method in practice is the controversy behind the nomenclature of the GI
vascular aberrations, their etiology and pathophysiology.