The data of 18 patients (8 male and 10 female) with complex AV malformations who were treated using percutaneous radiofrequency ablation in the Linyi Cancer Hospital between December 2014 and June 2019 were analyzed retrospectively. The total 18 cases are all extratruncular and infiltrating type based on the Hamburg Classification [15, 16]. The patients were aged 10–48 years, with a median age of 25.5 years. Among the cases, 14 had lesions in the maxillofacial region, 1 had lesions in the trunk, and 3 had lesions in the lower limbs; all of these lesions were diffuse, and most of them involved full-layer penetration from skin to mucosa. The lesion area of 10 × 7 cm ~ 28 × 32 cm was not good or ineffective before repeated embolization, sclerotherapy, or operation, and the lesions continued to develop; this included 6 cases of intraoral bleeding and 1 case of nasal bleeding.

All patients were examined via routine computed tomography angiography (CTA), which showed high-density shadow in the lesion area, obvious lesion enhancement, and unclear lesion boundaries. Vascular reconstruction showed a large number of tortuous and dilated thickened vascular masses and thickened blood supply arteries, along with a higher number of branches and abnormally large reflux veins on the affected sidecompared with the unaffected areas. A total of 15 cases were examined via feeding artery arteriography through femoral artery intubation under digital subtraction angiography (DSA).

The radiofrequency ablation (CC-1–220 radiofrequency ablation system, ValleyLab Inc., USA) was used in the present study. The radiofrequency ablation system adopted the ValleyLab cool-tip TM RF ablation system, special cold circulation pump, cool-tip radiofrequency ablation needle (electrode), needle tip exposed 2 cm, and a matching special skin electrode. The ultrasonic instrument adopted the PHILLIPS HD15 color ultrasonic diagnostic instrument with an ultrasonic probe frequency of 2–5 MHz.

The routine hematological examination included blood routine, liver function, renal function, blood glucose, blood coagulation, D-dimer, positive and lateral chest X-ray, and ECG examination. The treatment plan and technology of the present study were demonstrated and approved by the Linyi Cancer Hospital ethics committee, and the patients or their parents signed a treatment-related written informed consent form. The ablation plan was created via multidisciplinary consultation.

The lesion size, range, depth, needle insertion direction, and blood flow were detected via intraoperative duplex ultrasound. Under duplex ultrasound guidance, the site with the most abundant blood flow signals in the lesion was percutaneously punctured with the radiofrequency ablation needle (electrode), the impedance automatic adjustment mode was adopted, and the ablation power was maintained at 60–130 W. During the ablation process, the lesion was vaporized using high signal intensity under real-time Duplex Doppler ultrasound monitoring. With the continuous lesion vaporization around the tip in the process, the tissue resistance increased, and the ablation instrument automatically stopped working; this kept the puncture needle fixed during the time. After the gas in the ablation lesion tissue dissolved, the human tissue resistance decreased, and the ablation equipment started to work automatically until the ablated diameter reached 2–3 cm and the ablation vaporization tissue became round. Then, the radiofrequency needle was slightly withdrawn and radially adjusted along the original puncture needle eye to the peripheral lesion area with a rich blood supply; this continued until the electrode tip and ablation vaporization area edge were 1 cm apart. The area with a diameter of approximately 2–3 cm was then ablated again and repeatedly adjusted and ablated in the same needle path until an area with a diameter of approximately 6 cm was formed. The ablation needle was then removed, and other lesions with the most abundant blood supply were selected for ablation treatment once again.

The ablation technique and treatment parameters changed according to the different site operation; the ablation power was 60–130 W in the maxillofacial region, 90–130 W in the deep lesion center, and 60–80 W in superficial or relative marginal lesions. The treatment time of each ablation was 60–90 min, with an average of 76 min. The next treatment was repeated in about 3 months in accordance with the imaging results.

After the operation, the patient body temperature was monitored, skin color at the puncture point was observed, skin or tissue necrosis was recorded, urine color and volume were paid attention to, and peripheral nerve motor and sensory function were evaluated. The CTA was reexamined every 3 months after discharge.

The long-term evaluation of the lesions was based on objective imaging indicators, and the therapeutic effect was evaluated with reference to the grading criteria put forward by Achauer et al. [17]: grade I (poor), with a lesion reduction of 0–25%; grade II (medium), with a lesion reduction of 26–50%; grade III (good), with a lesion reduction of 51–75%; and grade IV (excellent), with a lesion shrinkage of 76–100%.

The participant characteristics are listed in Table 1. The length of hospital stay was 7–13 days, with a median of 9 days. The patients were treated once every 3 months at a total of 3–6 times, with a median of 5 times.

A total of 9 cases presented with fever and recovered after symptomatic treatment. Transient hemoglobinuria occurred in 4 patients after operation and intravenous infusion of 5% sodium bicarbonate solution alkalized urine, and tissue necrosis in the original ruptured tumor area, along with a penetrating defect in the cheek, occurred in 1 case patient; this defect was repaired with a pedicled trapezius myocutaneous flap and healed. A total of 2 patients experienced postoperative numbness with no dyskinesia and recovered 3 months after neurological treatment.

There were 9 cases of intraoral hemorrhage and 1 case of nasal hemorrhage. After one ablation treatment, the bleeding stopped, and no more bleeding occurred. During the follow-up of 1–5 years, there were 0 grade I (poor) cases, 0 grade II (medium) cases, 7 grade III (good) cases, and 11 grade IV (excellent) cases.

The first typical case was a 23-year-old female from the Jiangsu Province who had extensive AV malformations in the left chest wall. She had previously undergone 5 rounds of superselective arterial embolization and multiple injection sclerotherapy outside the hospital; however, the effects of these treatment methods were not good. The lesion continued to grow, and the pain in the lesion area was obvious in the past year. The pain was severe at night, affecting sleep and causing palpitation, shortness of breath, and difficulty getting up the stairs. The patient was admitted to the hospital on December 1, 2014. A physical examination showed an obvious tumor protuberance on the left side of the chest and back, an obvious increase in local skin temperature, palpable lifting pulsation and tremor, and a grade IV wind-like murmur during auscultation. Diagnosis: extensive AV malformations in the left chest wall with cardiac insufficiency. Multidisciplinary consultation showed that the patient had a wide range of lesions involving major thoracic vessels and other important structures, bone destruction, and multiple ribs and thoracic vertebrae (see Fig. 1). The surgical approach was difficult, and the possibility of causing uncontrollable massive bleeding during the operation was high. The risk of this method is still great even if the tissue defect is difficult to repair after resection; thus, it was not a suitable choice for the operation. Additionally, many thick blood supply arteries of the lesion originated directly from the thoracic aorta, and the collateral vessels and AV fistulas were extremely abundant (see Figs. 1, 2). Arterial and local interventional embolization may not be effective; however, embolization has been carried out several times in many large hospitals at a higher level. Clinical practice has proven that the lesion is still progressive and uncontrolled after treatment, and percutaneous radiofrequency ablation under ultra-real-time color monitoring can be performed. After 4 rounds (3–4 points each) of radiofrequency ablation treatment, the lesion was significantly reduced and the localized tenderness completely relieved. Moreover, the core tumor disappeared, the cardiac function gradually recovered, and shortness of breath and palpitations improved. Reexamination 3 years after treatment: the lesions of the left erector spine and intercostal muscles were further reduced and thinned; over 75% of the original enhanced lesions showed low density changes. The patient had a normal life with a grade III (good) curative effect evaluation.

The second typical case was a 21-year-old female with extensive AV malformations in the floor of the right tongue. The patient had undergone embolization and sclerotic injection many times in several major hospitals; however, the effects were poor, and the patient’s condition had gradually become aggravated. Following the sudden occurrence of oral bleeding and compression hemostasis, the patient was transferred to Linyi Cancer Hospital for treatment. The day after admission, the patient presented with jet bleeding, and the hemostatic effect of compression was not good. Tracheotomy was performed urgently, and iodoform gauze was sutured at the buccal mucosa of the affected side to stop the bleeding. Further examination of the CTA and DSA showed typical AV malformations of the right maxillofacial mouth and tongue as well as involvement of the maxilla and mandible (see Fig. 3a–f). Resection of the right mandible and multiple embolization of soft tissue lesions were performed under general anesthesia. However, the lesions continued to develop and were not controlled, especially those in the tongue and the floor of the mouth; this made it difficult for the patient to breathe and eat. Simultaneously, many instances of mucosal erosion and bleeding occurred in the oral lesion area after the operation. Following multidisciplinary consultation, percutaneous and mucosal radiofrequency ablation was performed under general anesthesia. After 1 round of ablation, there was no intraoral bleeding, and after 3 rounds (3–4 points each) of radiofrequency ablation, the tongue, mouth, and maxillofacial region lesions were reduced by over 85%. Furthermore, the core main tumor disappeared, the tracheal cannula and gastric tube were removed, and the patient’s breathing and eating returned to normal. The curative effect was evaluated as grade IV (excellent).