The "Little AVM": A New Entity in High-flow versus Low-flow Vascular Malformations

Combining superselective catheterization and electrochemotherapy: A new technological approach to the treatment of high-flow head and neck vascular malformations

Introduction

The study aims to demonstrate a combination of superselective catheterization and electrochemotherapy as a feasible and effective new technological approach in treating high-flow vascular malformations of the head and neck region.

Patients and methods

In the patient with high-flow arteriovenous malformation of the lower lip, superselective catheterization was performed under general anesthesia. The microcatheter was used to administer 750 IU BLM intra-arterially into the feeding vessel. The whole malformation surface was then covered with 15 applications of electric pulses using the plate electrode.

Results

Excellent response, without functional or aesthetic deficits, was obtained in 10 weeks. During this period, debridement and necrectomy were performed regularly on follow-up visits. The pain was managed with oral paracetamol and sodium metamizole.

Conclusion

Combining electrochemotherapy using bleomycin with superselective catheterization and arteriography is a feasible treatment option for high-flow vascular malformations in the head and neck region and could play a significant role in managing these challenging lesions.

Post-traumatic arteriovenous malformation of the superficial temporal artery

An arteriovenous malformation is a rare vascular anomaly composed of a complex network of interconnected arteries and veins of the scalp. It is usually congenital, but infrequently occurs after trauma. Over the years, several terms have been used to describe these lesions, such as cirsoid/rasemose/arteriovenous aneurysm, plexiform angioma and aneurysma serpentinum, or arteriovenous fistula when a single connection exists. Head and neck malformations occur in 0.1% of the population. Involvement of the superficial temporal artery is rare, occurring in about 0.5% to 2.0% of cases. They are diagnosed by angiography and can be managed by endovascular or open resection. The case of a 23-year-old man who presented with a pulsatile head mass after blunt trauma 5 years prior is presented. This entity was diagnosed as an arteriovenous malformation supplied by the superficial temporal arteries. He subsequently underwent successful open exploration and resection. The information is presented with the patient's consent.

Angioarchitecture and hemodynamics of microvascular arterio-venous malformations

Introduction

Arteriovenous malformations (AVMs) are characterized by pathological high flow, low resistance connections between arteries and veins. Treatment is critically dependent on correct interpretation of angioarchitectural features. However, some microfistular AVMs do not match the characteristics described in current AVM classification systems. Therefore, we propose a new subgroup of microfistular AVMs, composed of enlarged, fistulous paths on the venous half of capillaries and/or dilated draining venules (hyperdynamic, capillary-venulous malformation [CV-AVM]). CV-AVMs still ensure arterial flow to the periphery and fistulous venous drainage is less pronounced than in classical AVMs such that these lesions are often misinterpreted as venous malformations.

Materials and methods

We developed a computational model to study the effects of microvascular anomalies on local hemodynamics, as well as their impact on angiographic contrast propagation. Flow rates and pressures were computed with a lumped parameter description, while contrast propagation was determined by solving the 1D advection-diffusion equation.

Results and conclusions

For the newly proposed CV-AVM angioarchitecture, the computational model predicts increased arterio-venous contrast agent transit times and highly dispersive transport characteristics, compared to microfistular, interstitial type IV AVMs and high flow type II and III AVMs. We related these findings to time-contrast intensity curves sampled from clinical angiographies and found that there is strong evidence for the existence of CV-AVM.

Low-Flow Arterialized Venous Malformations of the Orbit

PURPOSE

Orbital vascular malformations are classified by their hemodynamic properties, either high or low flow. Low-flow lesions may be simple venous, lymphatic, or combined lymphaticovenous malformations. The authors report a series of cases in which predominantly low flow, venous lesions were unexpectedly noted to have arterial feeders.

METHODS

A retrospective chart review of patients identified by the authors as having orbital varices with arterial components was conducted. The authors identified 7 such cases. After careful review, 2 cases were excluded due to inconclusive neuroradiographic findings. The authors review the clinical, radiologic, histopathologic, and surgical information from the remaining 5 cases and discuss their clinical significance.

RESULTS

All 5 cases were most consistent with variceal lesions: 3 as clinically distensible lesions and 2 as thrombosed lesions. Additional arterial feeder vessels were noted by angiography (3) or intraoperative visualization (2). The arterial contribution varied from faint vessels to distinct branches of the ophthalmic artery. Ages ranged from 13 to 61 years without predilection for gender. Treatments consisted of excision, embolization, and observation. Two poignant cases are highlighted: the first illustrating that an angiogram in isolation of its clinical picture can be misleading and result in treatment intervention with undue risk, and the second illustrating that inadequate treatment of unrecognized arterial components may contribute to recurrences.

CONCLUSIONS

Low-flow orbital variceal lesions may have less prominent, arterial components. This type of combined arterialized venous malformation is largely unrecognized in the ophthalmic literature. Correct identification of these lesions is critical in providing safe, effective, and durable treatment.