Vascular Malformations and Congenital/Acquired Arteriovenous Fistulas

59.1Classify before you treat

The first decision in vascular anomaly care is not which device, sclerosant, embolic agent, or incision to use; it is whether the lesion has been named correctly. A referral label such as “AVM,” “haemangioma,” “varix,” “birthmark,” or “soft-tissue vascular mass” is not enough to plan treatment. The initial consultation should separate vascular tumors from vascular malformations, low-flow lesions from high-flow lesions, isolated disease from syndromic disease, and true malformations from acquired or congenital shunts. ISSVA terminology provides the shared language for that sequence and reduces the clinical harm created by legacy labels that mix tumor biology, malformation biology, and flow physiology. Identifying erroneously used 2023 · ISSVA classification vascular 2018

That classification changes the rest of the encounter. A vascular tumor has a different natural history and treatment logic from a venous, lymphatic, or arteriovenous malformation. A compressible low-flow venous or lymphatic lesion carries different procedural risks from a high-flow arteriovenous malformation with arterialised venous drainage. A syndromic pattern such as hereditary hemorrhagic telangiectasia, Klippel-Trenaunay, Parkes-Weber, or CLOVES may add family assessment, genetics input, cardiopulmonary screening, pediatric planning, or long-term surveillance to what first appeared to be a local extremity problem. Molecular context is increasingly relevant to prognosis and selected systemic therapy, but it should refine—not replace—the first clinical task of naming lesion biology and flow. Preliminary results European 2023 · ISSVA classification vascular 2022 · Targeted therapy patients 2018

The physical examination should deliberately look for the features that keep these lanes separate. Compressibility, bluish discoloration, dependency-related pain, phlebolith-type tenderness, recurrent swelling, lymphatic vesicles, leakage, and cellulitis history support a low-flow venous or lymphatic problem. Warmth, pulsatility, bruit, thrill, rapid expansion, bleeding, ulceration, prominent draining veins, distal perfusion change, or high-output features point toward shunt physiology and should stop any reflex plan for simple excision or low-flow sclerotherapy. Japanese vascular-anomaly guidance similarly emphasises clinical and imaging separation of low-flow and high-flow lesions before intervention. Japanese clinical practice 2017 · How treat peripheral 2021

Imaging should then answer the management question rather than merely document that a vascular mass exists. In a suspected low-flow malformation, the team needs extent, tissue planes, venous drainage, lymphatic predominance, and proximity to nerves, skin, mucosa, orbit, airway, and functional structures. In a suspected high-flow AVM, imaging must define arterial inflow, nidus, venous outflow, tissue involvement, and hemodynamic consequence before treatment is offered. In a suspected fistula, the question is where arterial flow enters the venous system, how chronic the shunt is, what distal perfusion remains, and whether venous or cardiac consequences are present. How treat peripheral 2021 · ISSVA classification vascular 2018

The useful output of the first visit is therefore a pathway, not a vague label. The patient may belong in low-flow malformation care for observation, compression, sclerotherapy, surgery, systemic-therapy discussion, or combined care; in high-flow AVM care for hemodynamic mapping and staged control; in an HHT or pulmonary AVM pathway for systemic screening and prevention; in a congenital shunt pathway; in an acquired traumatic or iatrogenic AVF pathway; or outside vascular anomaly care altogether. Disciplined classification is the safest treatment decision the surgeon makes.

59.2Low-flow malformations: treat to patient endpoints

Low-flow venous and lymphatic malformations should be treated to the patient’s clinical burden, not to a normal-looking scan. The indication for observation, compression, sclerotherapy, surgery, systemic therapy referral, or combined care should be anchored in pain, swelling, function, tissue integrity, cellulitis history, thrombosis history, deformity, bleeding, and quality of life. Imaging response matters when it explains symptom change or future risk, but volume reduction alone is a weak endpoint if the patient still cannot walk, sleep, work, use the limb, avoid infection, or tolerate daily activity. Conversely, persistent imaging abnormality may be acceptable when pain, function, skin protection, and patient goals have improved. Outcome evaluation treatment 2024 · Vascular Malformations Health-Related 2018 · Management venous malformations. 2021

Observation is an active plan when symptoms are absent, mild, stable, or outweighed by procedural risk. The plan should specify what is being watched: pain, dependency symptoms, skin change, bleeding, infection, thrombosis, growth, functional limitation, or emergence of high-flow signs. Conservative treatment also deserves a precise indication. Compression may help selected extremity venous or lymphatic malformations by reducing swelling and dependency-related symptoms; skin care and infection prevention become central when lymphatic disease, leakage, or cellulitis dominates. These measures preserve procedural options and should not be described as failure when they meet the patient’s endpoint. Japanese clinical practice 2017 · Management venous malformations. 2021

Image-guided sclerotherapy is a major option for symptomatic low-flow malformations, but it is not a generic injection for every visible lesion. Selection depends on lesion type, size, drainage, compartment, communication with normal veins, proximity to nerves, skin, mucosa, orbit, or airway, prior treatment, age, and the patient’s tolerance for staged care. The consent conversation should include why more than one session may be needed, what swelling after treatment may mean, which symptoms are expected to improve, and what complications would matter most in that anatomic site, including skin injury, neuropathy, tissue necrosis, airway compromise, or functional loss. Japanese clinical practice 2017 · Management venous malformations. 2021

Surgery is strongest when anatomy and clinical goal align: a discrete symptomatic lesion can be removed without unacceptable nerve, skin, airway, or functional loss; debulking will improve tissue mechanics; or operative treatment follows image-guided therapy to improve control of bleeding or residual disease. It is less attractive when the malformation is diffuse through critical planes, when excision would trade pain for disability, or when the dominant burden is better addressed with compression, staged sclerotherapy, infection prevention, or supportive care. Lesion size should not drive the decision alone; the chosen treatment must match the endpoint the patient actually needs. Japanese clinical practice 2017 · Management venous malformations. 2021

Systemic and molecular therapy belongs in this section only for selected patients, not as routine local treatment. Sirolimus has been studied for complex vascular anomalies and venous malformations, and PIK3CA-directed therapy has changed management discussions for selected PIK3CA-related overgrowth spectrum disease; these treatments require specialist selection, longitudinal toxicity monitoring, and clarity about the target symptom or complication. They should not be used to avoid good anatomic diagnosis, nor should they be presented as a substitute for local treatment when a discrete procedural endpoint is safer and clearer. Effectiveness safety sirolimus 2025 · Preliminary results European 2023 · Targeted therapy patients 2018

Follow-up should ask whether the treatment improved the problem it was chosen to improve. The record before intervention should name the target symptom, functional activity, tissue risk, bleeding or infection burden, and acceptable trade-off. After treatment, the key questions are whether the burden changed, whether new morbidity was created, and whether another treatment stage would add meaningful benefit. This longitudinal framing is especially important in children, diffuse lesions, syndromic disease, and patients who have already had repeated procedures, because technically successful interventions can still accumulate scarring, pain, anxiety, and functional loss. Outcome evaluation treatment 2024 · Vascular Malformations Health-Related 2018

59.3High-flow AVMs: map before intervening; aim for control, not cure

A peripheral high-flow AVM is a hemodynamic disease, not simply a vascular mass. Treatment should not begin because the lesion is visible, alarming, or anatomically reachable. Before intervention, the team should define inflow arteries, nidus configuration, venous outflow, tissue-plane extent, symptoms, progression, skin or mucosal threat, bleeding, ulceration, nerve or airway involvement, functional limitation, cardiac effect, and prior treatment. Doppler assessment, cross-sectional imaging with angiographic information, and selective angiography may all contribute, but the governing principle is simple: an unmapped AVM is not ready for treatment. Overview peripheral arteriovenous 2023 · How treat peripheral 2021 · Use transarterial approaches 2018

The indication to intervene should be clinical consequence, not cosmetic unease alone. Pain, bleeding, ulceration, tissue destruction, functional compromise, progression, or cardiac load may justify treatment; intervention for appearance alone is harder to justify when the procedure may recruit collateral flow, worsen swelling, injure skin, damage nerve or muscle, or create a more complex lesion. Site matters. Head and neck AVMs carry different risks from extremity, trunk, or visceral lesions; an approach that is reasonable for a contained extremity nidus may be unsafe near the airway, orbit, cranial nerves, or a fragile soft-tissue envelope. Interventional therapy extracranial 2022 · How treat peripheral 2021

When treatment is appropriate, it is usually a staged program with a stated purpose for each step. Embolisation may reduce flow, treat a bleeding point, close part of a nidus, or prepare for resection. Surgery may be appropriate for selected resectable disease or tissue-threatening lesions after flow has been controlled. Combined embolisation and resection can be useful when neither modality alone is likely to achieve the clinical endpoint. The operative or endovascular plan should state whether the aim is pain control, bleeding control, ulcer healing, preservation of function, reduction in shunt burden, or preparation for resection. Overview peripheral arteriovenous 2023 · How treat peripheral 2021

Outcome language should be honest. Peripheral and extracranial AVM series are heterogeneous, and recurrence, progression, and incomplete eradication are common enough that cure language is rarely safe. Long-term experience with ethanol embolotherapy in one anatomically defined AVM cohort illustrates the broader point: even aggressive treatment is best discussed as control of symptoms and shunt burden, not guaranteed elimination of disease. The better counseling script is that staged treatment may reduce pain, protect tissue, control bleeding, slow progression, improve function, and reduce hemodynamic burden, while the condition may still require surveillance and further treatment. Interventional therapy extracranial 2022 · Extracranial arteriovenous malformations 2025 · Ethanol embolization arteriovenous 2024

Molecular findings are changing selected vascular-anomaly care, but the statement should remain narrow. PIK3CA-related overgrowth spectrum disease is a slow-flow or combined overgrowth context in which targeted therapy has been reported; that experience should not be generalized into a claim that ordinary peripheral high-flow AVMs are routinely treated medically. For the vascular surgeon, the practical duty is to recognise when specialist vascular-anomaly input is needed, when staged intervention is justified, and when restraint is safer than an incomplete or poorly targeted procedure. Extracranial arteriovenous malformations 2025 · Targeted therapy patients 2018

The safest management question is therefore not “Can this AVM be embolised?” but “What problem are we trying to solve, and what harm might treatment create?” A high-flow AVM without tissue threat, bleeding, functional compromise, progression, or cardiac effect may be better observed with clear return triggers. A high-flow AVM that threatens tissue, function, airway, bleeding control, or cardiac status needs deliberate multidisciplinary planning before a catheter or knife is introduced. Japanese clinical practice 2017 · How treat peripheral 2021

59.4HHT and pulmonary AVMs are a separate referral lane

Hereditary hemorrhagic telangiectasia changes a local vascular-anomaly visit into a systemic-risk consultation. Second international guidelines 2020 Recurrent epistaxis, mucocutaneous telangiectasia, family history, hypoxaemia, paradoxical embolic events, brain abscess, gastrointestinal bleeding, anemia, or AVMs in multiple territories should move the patient out of routine peripheral AVM sequencing and into an HHT pathway. The international HHT guidance frames care around screening, family implications, pulmonary and cerebral assessment, bleeding management, genetics, and lifelong follow-up rather than local lesion treatment alone.

Pulmonary AVMs deserve particular attention because their consequences are not confined to the lung. Right-to-left shunting can cause hypoxaemia and can permit paradoxical embolic or septic complications, so the vascular surgeon should ask about unexplained dyspnea, oxygen desaturation, prior stroke-like events, brain abscess, and family history when the phenotype suggests HHT or pulmonary AVM. The intervention logic differs from peripheral extremity AVM care: the indication is prevention of pulmonary right-to-left shunt consequences as much as local symptom control. Second international guidelines 2020 · Approach pulmonary arteriovenous 2020 · Embolisation pulmonary arteriovenous 2018

This separation also prevents overtreatment. A patient with HHT may have multiple vascular lesions, but not every visible lesion should be embolised or excised. Second international guidelines 2020 The priority may be screening, prevention of paradoxical events, management of epistaxis, treatment of anemia, genetic counseling, family evaluation, or observation. Conversely, a patient referred with an apparently isolated peripheral malformation may be the first person in a family in whom HHT is recognised. In both directions, the syndrome diagnosis changes what the surgeon owes the patient beyond the visible lesion.

The technical vocabulary can be misleading because embolisation is used in both peripheral AVM and pulmonary AVM care. The shared word does not make the diseases interchangeable. Peripheral AVM treatment is usually framed around local tissue threat, bleeding, function, progression, and shunt control; pulmonary AVM treatment is embedded in HHT screening, right-to-left shunt prevention, pulmonary assessment, and follow-up. When HHT features or pulmonary AVM concerns are present, referral into a dedicated HHT and pulmonary AVM pathway is not a delay in care. It is the disease-matched pathway. Second international guidelines 2020 · Approach pulmonary arteriovenous 2020

The practical boundary is therefore strict: peripheral high-flow AVMs, pulmonary AVMs, and HHT-related multisystem disease should not be collapsed into one treatment script. A vascular surgeon can recognise the red flags, avoid inappropriate local intervention, protect the patient from preventable embolic or septic complications, and involve the team that can manage screening and family implications. Second international guidelines 2020 · Embolisation pulmonary arteriovenous 2018

59.5Congenital and acquired arteriovenous fistulas are shunts, not low-flow malformations

Congenital AVFs, acquired traumatic AVFs, and iatrogenic AVFs should be separated from venous and lymphatic malformations at the first diagnostic pass. They are shunts: arterial pressure and flow enter the venous system through an abnormal communication. That hemodynamic fact changes the physical signs, imaging questions, urgency, and treatment endpoints. A low-flow malformation may be managed around observation, compression, sclerotherapy, surgery, systemic-therapy discussion, or symptom control; an AVF is managed around shunt closure or exclusion, relief of venous hypertension, preservation of distal perfusion, and reduction of cardiac burden when present. ISSVA-based classification supports the separation of malformation categories from arteriovenous shunt physiology. Japanese clinical practice 2017 · ISSVA classification vascular 2018

A congenital AVF may have been incorporated into the patient’s circulation over years, with enlarged feeding arteries, arterialised veins, local tissue effects, and sometimes cardiac adaptation. The treatment question is not whether the abnormal channel can be made smaller on imaging; it is whether closure, exclusion, or flow reduction will improve symptoms while preserving necessary distal perfusion and avoiding tissue loss. Evaluation should define inflow, outflow, distal arterial supply, venous hypertension, skin and soft-tissue condition, symptoms, and evidence of cardiac consequence. Japanese clinical practice 2017 · ISSVA classification vascular 2018

Acquired AVFs are different again because the clinical story often begins with trauma, arterial puncture, catheter placement, operation, or other instrumentation. A pulsatile mass, bruit, thrill, new venous hypertension, limb swelling, distal ischemic symptoms, bleeding, pseudoaneurysm, or unexplained high-output physiology after vascular injury should prompt evaluation for traumatic or iatrogenic shunt physiology. The ESVS vascular trauma guidance belongs here: it supports treating traumatic AVF and associated arterial injury as vascular trauma problems with their own anatomy, urgency, and repair strategy, not as congenital malformations. Editor's Choice European 2025

Treatment selection for an acquired traumatic or iatrogenic AVF depends on the injury site, chronicity, associated pseudoaneurysm or arterial defect, venous hypertension, distal perfusion, infection or contamination risk, tissue injury, and whether open, endovascular, or hybrid exclusion can close the shunt safely. The objective is usually elimination of the abnormal communication while preserving necessary arterial and venous pathways. This is distinct from the staged symptom-control approach used for diffuse venous or lymphatic malformations and from the disease-control program used for many peripheral AVMs. Editor's Choice European 2025

This boundary prevents both undertreatment and overtreatment. A traumatic AVF mislabelled as a malformation may be observed until venous hypertension, tissue damage, distal perfusion problems, or cardiac burden progresses. A venous malformation mislabelled as a fistula may be exposed to unnecessary arterial procedures. The examination should therefore seek shunt signs deliberately: bruit, thrill, pulsatility, arterialised venous flow, post-injury timing, venous hypertension, distal perfusion change, and high-output physiology. When those findings are present, the patient belongs in the shunt pathway. Editor's Choice European 2025 · Japanese clinical practice 2017

Dialysis-access fistulas require a separate framework because they are intentionally created shunts with goals of access maturation, dialysis adequacy, surveillance, salvage, and complication control. The pathological shunts discussed here are different: congenital AVFs and acquired traumatic or iatrogenic AVFs in which the purpose of treatment is to remove or control abnormal haemodynamics. Keeping that distinction visible helps the surgeon choose the correct reasoning pathway before choosing the procedure.