Congenital Vascular Malformations

Congenital Vascular Malformations

Doppler ultrasound and magnetic resonance imaging (MRI), have assumed a dominant role in imaging these lesions. Magnetic Resonance Imaging In our exp...

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Doppler ultrasound and magnetic resonance imaging (MRI), have assumed a dominant role in imaging these lesions.

Magnetic Resonance Imaging In our experience, MRI is the definitive tool for crosssectional imaging of vascular malformations. Rak et al (7) identified and characterized the MR appearance of malformations, including venous malformations, AVMs, and arteriovenous fistulas, and showed that MRI was essential in separating vascular lesions into high-flow and low-flow types (7). The predominant distinction between venous malformations and AVM and fistulas is on T2-weighted MR images. On these sequences, venous malformations have very high signal intensity (i.e., they are "bright"). Arteriovenous fistulas and AVMs show little or no signal because of the phenomenon known as "flow void." In addition, magnetic resonance imaging shows involvement of neural, subcutaneous, muscular structures, or all three, because of its superior tissue differentiation. The multiplanar imaging capabilities of MRI also allow localization and characterization of complex lesions whether they are located in the trunk or extremities. Regarding computed tomography (which we have used in the past), we have found that MRI is superior in virtually all aspects to computed tomography; and except for specific situations, we have abandoned the use of computed tomography in the work-up and evaluation of vascular malformations. Color Doppler Ultrasound Color Doppler ultrasound has also been useful in identifying high-flow and low-flow vascular lesions. We have also found this technique essential in guiding direct puncture of malformations by permitting accurate localization of the nidus. Follow-up examination is commonly used to document the decreased vascular flow rates and thromboses that occur after successful therapy.

References 1. Yakes WF, Parker SH. Diagnosis and management of vascular anomalies. In: Castaneda-Zuniga WR, Tadavarthy SM, eds. Interventional Radiology, Vol 1. Baltimore: Williams and Wilkins, 1992, pp 152-189. 2. Szilagyi DE, Smith RF, Elliott]D, Hageerman]H. Congenital arteriovenous anomalies of the limbs. Arch Surg 1976; 111423-429. 3. Gomes AS, Mali WP, Oppenheim WL. Embolization therapy in the management of congenital arteriovenous malformations. Radiology 1982; 144:41-49. 4. Kaufman SL, Kumar AA], Roland ]MA. Trascatheter embolotherapy in the management of congenital arteriovenous malformations. Radiology 1980; 137:2129. 5. Doppman ]L, Pevsner P. Embolization of arterio-

venous malformations by direct percutaneous puncture. A]R 1983; 140:773-778. 6. Mulliken ]B, Young AE, eds. Vascular Birthmarks: Hemangiomas and Malformations. Philadelphia: WE Saunders, 1988. 7. Rak KJ.\1, Yakes WF, Ray RL, et al. Imaging of symptomatic peripheral vascular malformations. A]R 1992; 159:107-112. 11:30 am Congenital Vascular Malfonnations

Robert]. Rosen, MD New York University Medical Center New York, New York Arteriovenous lesions can be divided into four major types: (1) infantile hemangiomas, which are benign neoplasms; (2) arteriovenous fistulas, which are usually acquired lesions; (3) true arteriovenous malformations (AVMs), which are congenital anomalies; and (4) predominantly venous lesions, including dysplasias and cavernous venous malformations. Infantile Hemangiomas Over the years, the tenn hemangioma has been applied to a wide variety of vascular lesions, causing considerable confusion in the literature regarding diagnosis and treatment. There is now general agreement that this term should be used to refer only to the the benign vascular neoplasm usually encountered in infancy and childhood. These lesions are present at birth in 30% of cases, with the rest appearing in the first few months of life. Typically, they undergo a period of rapid growth in the first 6 months of life, pathologically demonstrating marked proliferation of endothelial cells. The proliferative phase is generally followed by spontaneous gradual involution beginning at about 1 year and continuing to resolution by age 7 in 95% of patients. The distinctions between the pathology and clinical behavior of this lesion and true congenital vascular malformations have been emphaSized in the classification of Mulliken and Glowacki (2). Although hemangiomas can occur anywhere in the body, the most typical lesion appears as a red or reddishblue, flat or slightly raised skin lesion. They are generally isolated lesions but can be multiple in 30% of cases. Most represent a purely cosmetic problem, but during the proliferative phase, endothelial proliferation is manifested clinically by rapid growth that can be not only disfiguring but also life threatening in extreme cases, because of involvement of respiratory or gastrointestinal structures. Extensive lesions, especially those in the liver, can be associated with high-output congestive heart failure. These hepatic lesions are associated with a high mortality rate, but if the infant can be supported through the early stages, involution will occur as in other hemangiomas. Thrombocytopenia and consequent hemorrhagic


complications have been associated with hemangiomas, and this is called Kasabach-Merritt syndrome. It now appears that this phenomenon is confined to a different pathologic entity with a more aggreSSive course, called Kaposiform hemangioendothelioma.

Treatment It is generally agreed that the most common small superficiallesions should be managed conservatively, because they are likely to involute with minimal or no residua. It is also apparent that extremely large, disfiguring, or life-threatening lesions require specific treatment. Treatment options include systemic corticosteroids, pulsed dye laser, intralesional injection, interferon, embolization, and surgery. In each of these approaches, a careful risk-benefit analysis is necessary. Steroid therapy, although effective and usually well tolerated, may be associated with potential problems such as interference with growth and development, immune suppression, and behavioral changes. Interferon treatment was recently reported to be associated with the development of spastic diplegia in some children. Laser treatment is generally effective in superficial lesions only, which also tend to show the most complete spontaneous involution. Transcatheter embolization has a limited role but can be lifesaving in extensive hepatic hemangiomatosis. In this disease, death is generally caused by massive shunting that results in high-output congestive failure. Particulate embolization has been used successfully to reduce the degree of shunting, allowing the infant to survive until the involution phase of the lesion occurs. Surgical management of hemangiomas is generally reserved for aggressive lesions that cause interference with respiratory or visual structures, or those that tend to have a poor cosmetic outcome even after involution, such as those on the lip or nose and pedunculated or ulcerated lesions. Large superficial lesions are often associated with areas of epidermal atrophy and telangiectasia after involution; deeper lesions may leave behind abnormal excess skin or fibrofatty tissue. Both of these may require cosmetic surgery for an optimal result.


Congenital Vascular MaHonnations Arteriovenous malformations are congenital anomalies resulting from faulty development of arterial, capillary, venous, or lymphatic structures or any combination of these. These lesions are thought to be present from birth and do not represent neoplasms. Most of these lesions occur sporadically in othelwise healthy persons, although there are rare but well-known syndromes (Rendu-Osler Weber) that are clearly familial. Vascular malformations differ from true hemangiomas in that they are not neoplasms. The work of Folkman, Mulliken, and their associates has shown that there is no endothelial proliferation and no cellular stroma in these lesions, nor do they show growth in tissue culture. These lesions do not exhibit the sequence of rapid proliferation followed by spontaneous involution that is characteristic of hem-

angiomas encountered in infancy and childhood. Congenital AVMs, like other congenital anomalies, remain incompletely understood in terms of pathogenesis. From a clinical perspective, patients can be assured that (1) these are malformations, not neoplasms, (2) they are generally isolated anomalies, (3) they are rarely genetically transmitted, and (4) they are often stable lesions requiring no specific treatment. The cllnical behavior of vascular malformations varies. They can remain dormant for years, and undoubtedly many are undetected throughout life. There is no apparent sexual predOminance, as there is with infantile hemangiomas. Gradual enlargement of the malformation occurs in proportion to the growth of the person. Detection may result from the observation of a skin discoloration, palpation of a mass, recognition of secondary effects of the lesion on adjacent normal structures, or they may be discovered through their complications, such as hemorrhage, ulceration, or ischemia of regional tissues. Some lesions become apparent after trauma or during periods of hormonal stimulation as in menarche or pregnancy. Measured cardiac output may be increased in patients with AVMs, but clinically significant cardiovascular effects are uncommon, in contrast to acqUired arteriovenous fistulas. In our series of 215 patients with congenital AVMs, only three showed evidence of a clinically Significant high-output state. The relative rarity of highoutput failure is not well understood, because the degree of angiographically observed shunting in some lesions is striking. Some authors have postulated that the multiple tortuous vessels that comprise these lesions may allow peripheral resistance to be maintained, despite a large total cross-sectional area of arteriovenous communication. Clinically significant high-output states associated with AVMs tend to occur in two settings: lesions in infancy and extremely large (usually pelvic) lesions in adults. A lesion that is relatively asymptomatic or even silent clinically may thus require treatment because of its generalized cardiovascular effects. Computed tomography and magnetiC resonance imaging are both extremely helpful in delineating the true extent of AVMs. The lesion itself and the involvement of adjacent structures, including muscle and bone, are well demonstrated in most cases. Magnetic resonance imaging also distinguishes between high- and low-flow components. Often these studies show the lesion to be much more extensive than expected based on clinical or even angiographic findings. Magnetic resonance angiography, using intravenous gadolinium contrast agents and specific imaglng sequences, represents a major advance in imaging vascular malformations. We have adopted magnetic resonance angiography as the preferred imaging method for initial evaluations of vascular malformations and for follow-up studies. Any lesion of significant size that is symptomatic enough to warrant therapeutic intervention should undergo angiographic evaluation. Angiography will con-

firm the presence of a vascular lesion and generally allow its differentiation from a vascular tumor. The study will demonstrate the flow characteristics of the lesion and delineate feeding arteries and draining veins and their relation to the nonnal circulation of the region.

Treatment Congenital vascular malformations present an extremely difficult therapeutic challenge. Asymptomatic or mildly symptomatic lesions do not require treatment once the nature of the mass has been confirmed. Absolute indications for t.reatment include hemorrhage, secondary ischemic complications, and congestive heart failure from arteriovenous shunting. Relative indications include pain, functional impainnent, and cosmetic deformity, including limb asymmetry associated with extremity lesions. Hemorrhage is uncommon but may occur when the lesion is in an area subject to trauma or when there is a potential communication between the lesion and a mucosal surface such as the gastrointestinal tract or urinary bladder. Ischemic complications result from the "stealing" of flow from normal structures and can be manifested by pain and ulceration in extremity lesions and neurologic symptoms when the lesion involves the central nervous system. These ischemic complications often can be significantly improved by reducing the magnitude of arteriovenous shunting, even if the lesion cannot be eradicated completely. Pain and ulceration also may be related to chronic venous hypertension. In thiS situation, the usual measures to treat chronic venous lesions (local wound care, elastic compression, elevation, removal of specific symptomatic veins) can be used in addition to efforts to treat the underlying problem. If treatment is required, careful planning is mandatory, A team approach is often necessary that involves the appropriate specialists to achieve the optimum result. The patient must be made aware of the complex nature of the problem and the considerable uncertainties involved in treatment. Patients with symptomatic lesions judged to be resectable by careful preoperative evaluation probably should undergo surgery, because complete removal provides the best chance for cure. This is most suitable for superficial lesions of the trunk, scalp, face, and extremities. The goal of surgery should be complete resection of the lesion. Ligation of feeding arteries is only temporarily effective, and the rapid recruitment of collateral channels makes further treatment difficult or impossible. Transcatheter embolization now plays a Significant role in the treatment of many vascular malformations. Macroscopic occluding devices such as coils or detachable balloons are eqUivalent to surgically ligating arterial feeders and should not, in general, be used. Proximal occlusion, whether performed surgically or with embolization, may produce an impressive result initially, but reCU1Tence can nearly always be anticipated. Recurrences after proximal ligation or embolization are extremely difficult to treat because of recruitment of mul-

tiple new sources of blood supply to the lesion. We have encountered patients in whom mildly symptomatic lesions became severely symptomatic or even life threatening because of hemorrhage or ischemia after proXimal occlusion. Deeply penetrating particulate or liqUid embolic agents at least theoretically offer the possibility of eradicating the nidus of the lesion. These materials include plastic particles, ethanol and sclerosing agents, and liquid adhesives. Polyvinyl alcohol foam particles are available in graded diameter sizes from 50 to 1,000 IJ-m. They are injected as a suspension and become lodged in the small vessels of the malformation. Although a good initial angiographic result can be obtained, recanalization of vessels around the particles frequently results in early recurrence. Some authors have been proponents of intraalterial absolute ethanol as the agent of choice in treating highflow AVMs. This agent is unquestionably effective in permanently occluding vessels but is highly tissue toxic and may result in complications such as nerve injury and necrosis of normal tissues. Rapidly polymerizing acrylic adhesives and other investigational agents also have been used in an effolt to obliterate high-flow vascular malformations. Despite the technical complexity involved in delivering these agents superselectively, excellent long-term results have been achieved. Potential complications of any embolization procedure include tissue necrosis, inadvertent embolization of normal tissues, and passage of embolic materials through arteriovenous communications, resulting in pulmonary embolization. In our series of 215 patients with congenital vascular malfonnations outside the central nervous system treated by transcatheter embolization in an IS-year period, the overall incidence of complications was 6%. Three patients had major complications, including temporary hemiparesis in two patients with thoracic lesions and intractable hematuria in a patient with an extensive pelvic malformation. Three patients had embolization of embolic materials to the lungs documented radiographically. None of these patients had any clinical sequelae or change in pulmonary function studies. No procedural deaths occurred in our series. Because many therapeutic interventions wiJl produce an early response only to be followed by recurrence, the efficacy of any given form of treatment must be judged on the basis of long-term results. Of the 215 patients in our series, 25% are asymptomatic and have no radiologic evidence of residual or recurrent malformation at least 3 years after treatment. Thirty percent are asymptomatiC but show evidence of residual or recurrent malformation clinically or on computed tomography, magnetic resonance imaging, or angiographic studies. Another 21 % are significantly improved but still symptomatic. Twenty percent have had little or no change in symptoms, and 4% are more symptomatic or have different but more



severe symptoms related to a complication of the procedure.

suspension is injected through the sheath as it is withdrawn to seal the tract and prevent bleeding.

Venous MaHonnations

Treatment Localized symptomatic lesions may be treated by excision, although as noted previously, they may be more extensive than is evident clinically. Considerable cosmetic deformity may also result from the excision. Embolization of arterial branches supplying the lesion has been attempted with disappointing results, as might be anticipated from the fact that the lesion does not contain significant arteriovenous communications. Direct puncture, as described before, followed by sclerosis using absolute ethanol, has been more effective, with marked shrinkage of the lesion in many cases. The treatment of Klippel-Trenaunay syndrome is controversial, but most authors advocate conservative management using support stockings, epiphysiodesis in the case of children with marked leg-length discrepancy, and vein stripping only for specific veins that are causing discomfort. Contrast venography should be performed to evaluate the adequacy of the deep veins before any vein stripping or embolization procedure. Extensive venous stripping often results in marked worsening of symptoms. Servelle (7) reported good clinical results after operations to repair sites of venous obstruction, which he postulates to be the primary cause of the entire syndrome. The syndrome generally follows a benign but troublesome course in most patients.

Venous malformations are most commonly composed of large venous spaces under low pressure, with no clinical or angiographic evidence of significant arteriovenous shunting. They may occur anywhere in the body. When close to the skin surface, they have a distinct bluish discoloration, and the overlying skin may be thinned, even to the extent that ulceration and spontaneous bleeding occur. Cavernous lesions often can be emptied by manual compression or elevation, showing slow refilling when pressure is released or the lesion is placed in a dependent position. Venous lesions are often asymptomatic but may be disfiguring if large or in an exposed area. Pain may occur with venous distension or when the lesion is in a dependent position. Some venous lesions infiltrate an individual muscle or compartment, causing diffuse swelling and pain after exertion. Localized pain and tenderness can also result from focal areas of thrombosis within a lesion, with findings similar to a superficial phlebitis on physical examination. Klippel-Trenaunay syndrome is a specific complex of congenital abnormalities affecting one or more limbs, consisting of extensive varicosities, venous anomalies and malformations, capillary malformations (port wine stains), limb hypertrophy, and in some cases, lymphatic abnormalities. This is probably the vascular malformation most frequently encountered in clinical practice. The cause of this syndrome remains obscure, with some authors postulating fetal venous obstruction, others invoking microscopic A-V communications, and still others attribute the syndrome to a mixed mesodermal and ectodermal dysplasia. Similar findings of unilateral varicosities, limb hypertrophy, and cutaneous pigmentation may be seen with AVMs; differentiation is based on the angiographic absence of shunting. Venography mayor may not demonstrate a communication between the deep veins and a venous malformation. In Klippel-Trenaunay syndrome, venography typically demonstrates dysplastic veins, often including a persistent lateral embryonic avalvular vein. Hypoplasia or aplasia of the deep venous system is often found in these patients and represents a contraindication to removal of large superficial veins. An effective method of studying cavernous venous malformations is direct puncture angiography, which is performed by entering the lesion directly using a smallcaliber sheathed needle. The actual skin entry is made through adjacent normal skin, entering the lesion subcutaneously to avoid bleeding. Slow contrast injection under fluoroscopic control will show filling of irregular venous spaces, with eventual opacification of draining veins in most cases. As these lesions may be compartmentalized, more than one injection may be required to study the entire lesion. A small amount of a collagen

References 1. Eichenfield LF. Evolving knowledge of hemangio-

mas and vascular malformations. Arch Dermatol 1998; 134:740-742. 2. Mulliken]B, Glowacki]. Hemangiomas and vascular malformations in infants and children: a classification based on endothelial characteristics. Plast Reconst Surg 1982; 69:412. 3. Stanley P, Grinnell VS, Stanton RE, et al. Therapeutic embolization of infantile hepatic hemangioma with polyvinyl alcohol. A]R 1983; 141:1047. 4. Enjolras 0, Wassef M, Mawyer E, et al. Infants with Kasabach- Merritt syndrome do not have "true" hemangiomas.] Pediatr 1997; 130:631-640. 5. Frieden I], ed. Special symposium: Management of hemangiomas. Pediatr Dermatol 1997; 14:57-83. 6. Barlow CF, Priebe C), Mulliken ]B, et al. Spastic diplegia as a complication of interferon alfa-2a treatment of hemangiomas of infancy. ] Pediatr 1998; 132:527-530 7. Servelle M. Klippel and Trenaunay's syndrome: 768 operated cases. Ann Surg 1985; 201 :365. 8. Cohen ]M, Weinreb ]C, Redman He. Arteriovenous malformations of the extremities: MR imaging. Radiology 1986; 158:475.

9. Yakes WF, Luethke JM, Merland JJ, et al. Ethanol embolization of arteriovenous fistulas; a primary model of therapy. ]VIR 1990; 1:89. 10. Szilagyi DE, Smith RF, Elliott JP, et al. Congenital arteriovenous anomalies of the limbs. Arch Surg 1976; 111:423. 11. Boxt LM, Levin DC, Fellows KE. Direct puncture angiography in congenital venous malformations. AJR 1983; 140:135. 11:45 am AVMs---How I Treat Them: Alcohol Wayne F. Yakes, MD Vascular Malformation Center Englewood, Colorado Learning objectives: (1) Become more adept in the diagnosis of vascular malformations and the clinical problems they cause; (2) Understand the role of the endothelial cell in A 11M recanalization, neovascular recruitment phenomenon, and recurrence with the use of embolic agents that spare the endothelial cell during vascular occlusion procedures; (3) Understand the permanence of therapy with ethanol as an embolic agent because of the destruction of the endothelial cell; (4) Understand the dangers (potential complications) of non-target embolization with ethanol; (5) Understand the needfor a vascular malformation team which functions much like a tumor board team ofspecialists; (6) Be aware ofthe needfor general anesthesia and additional Swan-Ganz line and arterial line monitoring during ethanol embolization procedures; (7) Be aware of the postprocedure management ofpatients; (8) Understand the role of MRi and color Doppler imaging in vascular malformation diagnosis, management, and follow-up. Arteriovenous malformations (AVMs) constitute some of the most difficult diagnostic and therapeutic dilemmas in the practice of medicine. The clinical presentation can range from an asymptomatic birthmark to life-threatening congestive heart failure. Attributing any of these varied symptoms to a vascular malformation can be challenging to the most experienced clinician. Compounding the problem is the relative rarity of these lesions. If a physician encounters only one patient with this condition every few years, it is difficult to develop sufficient experience for diagnosis and optimal treatment. Typically, these patients seek help from a number of physicians, only to experience disappointing outcomes, complications, and recurrence or deterioration of their presenting symptoms. Here we present our approach to the diagnosis and treatment with' ethanol endovascular therapy. Initial Evaluation A thorough clinical examination and history usually can establish the diagnosis of pediatric hemangioma or vascular malformation. Hemangiomas usually are not present at bilth and have a bright scarlet color that

gradually deepens. Vascular malformations have a persistent color, depending on the dominant arterial, capillary, venous or lymphatic component. Evaluating for skeletal abnormalities, abnormal veins, arterial abnormalities, pulsatility or nonpulsatility of a lesion, dependent swelling or flattening on elevation, and disparity of limb size, along with neurologic evaluation and a good history often can enable diagnosis and even categorization of a vascular malformation. The Nicoladoni-Branham test of in-flow arterial occlusion, if positive, results in a reflex bradycardia if the AVM is of such a high flow that it is causing cardiac consequences. Color Doppler imaging (CDI) is an essential tool in the diagnostic workup of AVMs. Accurate measurements of flow volumes (a calculated physiologic parameter) and resistive indexes not only can be very helpful in the initial evaluation but also are important noninvasive parameters for follow-up after therapy. Documentation of decreased arterial flow volumes and normalization of the resistive indexes are very specific and may obviate the need for repetitive follow-up arteriography (1). Magnetic resonance (MR) imaging has replaced computed tomography (CT) in the evaluation of vascular malformations. It has proved to be a mainstay in the initial diagnostic evaluation as well as in assessing the efficacy of endovascular therapy. MR can distinguish accurately between high-flow and low-flow malformations, and the relationship to adjacent anatomic structures, such as muscles, nerves, and organs, is easily determined. High-flow malformations typically demonstrate signal void on most sequences. On gradient-echo sequences, increased signal within the vascular structures is present. At follow-up, MR can accurately determine residual areas of AVM as well as those areas that have been treated (2). After the diagnosis has been established, the next major decision is to determine whether therapy is warranted. The interventional radiologist should plan and direct the patient's care with surgical specialists who are familiar with AVM management and the problems they present with. It is extremely important that appropriate surgical, medical, pediatric, and anesthesiology specialists and subspecialists be involved for optimal patient care. Pain Control Pain control is a significant problem with the use of intravascular ethanol. Anesthesiologists can aid greatly in controlling pain and determining whether general anesthesia or intravenous (IV) sedation is required for the procedure. This leaves the interventional radiologist free to concentrate on the case at hand. For children, general anesthesia is required. In patients with large AVMs, Swan-Ganz and arterial line monitoring are performed. Pulmonary artery pressures are consistently monitored during the injection of absolute ethanol. Decadron (dexamethasone sodium phosphate, USP, Merck & Co., Inc., West Point, PA) is