More information: What are AVMs?

Medicine distinguishes between vascular tumours (haemangiomas) and pathological vessel connections (vascular malformations) (Table 1). The differences between haemangiomas and vascular malformations are summarised in Table 1. There are also mixed forms, which makes a standardised approach to such lesions difficult.

Table 1:
Differences between haemangiomas and vascular malformations (from 4)

 HaemangiomaVascular malformation
Special characteristicsExhibits cellular proliferationMade up of dysplastic vessels
DevelopmentSmall or absent at birthAlready present at birth
GrowthRapid growth during early childhoodGrowth proportional to the patient’s growth
ResolutionInvolution / resolution during late childhoodNo regression / resolution

Vascular malformations are defects in the vessels’ embryonic development and are always present at birth, although they may not necessarily be visible or symptomatic. The malformations can arise from the arterial, capillary, venous or lymphatic vascular system (Table 2). With regard to the fluid velocity in the abnormal vascular connections, vascular malformations are classified into two groups: Malformations with fast blood flow (high-flow) and malformations with slow blood flow (low-flow) (Table 3).

Table 2:
Simplified ISSVA classification of vascular anomalies

Vascular tumourVascular malformations
SimpleComplexFlow
HaemangiomaCapillary
Venous
Lymphatic
Lymphatico-venous (LVM)
Capillary-lymphatico-venous
Slow
Haemangioendothelioma angiomaArterial / arterio-venous malformation (AVM)Capillary-arterio-venousFast

Table 3:
Classification into high-flow and low-flow malformations according to Burrows & Mulliken 1983 (7)

MalformationHigh-flowLow-flow
DefinitionConnection to the arterial or capillary vascular systemConnection to the venous or lymphatic vascular system
ExamplesArterio-venous fistula
Arterio-venous malformation
Venous malformation
Lymphatic malformation
Capillary malformations
Combined types
TreatmentTrans-arterial embolisationSclerotherapy

High-flow malformations have a connection to the arterial or capillary blood vessel system, whereas low-flow malformations have connections to the venous or lymphatic vascular system (Figure 1).

Figure 1:
A An infantile haemangioma is made up of a solid cellular mass (grey) with an organised, glandular (aziniform) arrangement of the supplying arteries (red) and drainage into one or more enlarged (dilated) regional veins (blue).
B An arterio-venous fistula (AV fistula) is a sharply delimited (focal) macrosopic connection between an artery and a usually dilated vein.
C An arterio-venous malformation usually comprises a core (nidus) with arterio-venous connections (shunts) and a network of abnormal vascular channels with supplying arteries and draining veins.
D The venous malformation is a vascular dilatation after the capillary level (post-capillary lesion) made up of abnormally-shaped, dilated venous vascular channels. Larger veins can be incorporated into them.
E A lymphatic malformation is made up of fluid-filled spaces or channels that are surrounded by lymphatic endothelium. These hollow spaces are like rabbit warrens, filled with lymphatic fluid and have no significant flow.

Figure 2: Angiographic classification of arterio-venous malformations (AVM):
Typ I (arterio-venous fistula): Shunt connection (S) between at least three separate arteries (A) and a single draining vein (V)
Typ II (arteriolo-venous fistula): Shunt connection (S) between multiple arteries (A) and a draining vein (V)
Typ III (arteriolo-venulous fistula): Multiple shunt connections (S) between arterioles (A) and venules (V)

Figure 3: Arterio-venous malformation of the 4th toe of the right foot with significant vessel malformation on arterial angiography (left image). Using a thin needle, the hyper-vascular area at the base of the 4th toe (middle image) was pierced and embolisation was performed using gel-like alcohol (Sclerogel). Following sclerotherapy there was a significant reduction in blood supply (right image) and the patient’s symptoms improved.

Figure 4: Pulmonary arterio-venous malformation in which the shunt connection was closed using two vascular plugs inserted via the pulmonary artery.

Figure 5: Combined trans-venous sclerotherapy with high-percentage alcohol gel (Sclerogel) and trans-arterial embolisation with a tissue adhesive (Onyx) in a total of two sessions. Top images: Malformation in the area of the left shoulder with space-occupying effect and pain prior to embolisation. Middle images: Result after the first therapy session with marked reduction in vascularisation. Bottom images: Result after the second session of combined therapy.

If you have any questions about the treatment of vascular malformations, please do not hesitate to contact us. We would be delighted to assist you!

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Nozaki T, Matsusako M, Mimura H, Osuga K, Matsui M, Eto H, et al. Imaging of vascular tumors with an emphasis on ISSVA classification. Japanese journal of radiology. 2013;31(12):775-85.

Hyodoh H, Hori M, Akiba H, Tamakawa M, Hyodoh K, Hareyama M. Peripheral vascular malformations: imaging, treatment approaches, and therapeutic issues. Radiographics. 2005;25 Suppl 1:S159-71.

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Lee BB, Baumgartner I, Berlien HP, Bianchini G, Burrows P, Do YS, et al. Consensus Document of the International Union of Angiology (IUA)-2013. Current concept on the management of arterio-venous management. International angiology : a journal of the International Union of Angiology. 2013;32(1):9-36.

Burrows PE, Mulliken JB, Fellows KE, Strand RD. Childhood hemangiomas and vascular malformations: angiographic differentiation. AJR Am J Roentgenol. 1983;141(3):483-8.