Original Article

118 Ann Thorac Cardiovasc Surg Vol. 17, No. 2 (2011)

Coil Embolization for Pulmonary Arteriovenous Malformation as an Organ-sparing Therapy:

Outcome of Long-term Follow-up

Koji Ando, MD,1 Atshushi Mochizuki, MD,1 Noriaki Kurimoto, MD,1 Kumio Yokote, MD,1

Yasuo Nakajima, MD,2 Hiroaki Osada, MD,3 and Haruhiko Nakamura, MD1

1Chest Surgery, St. Marianna University School of Medicine, Kawasaki, Kanagawa, Japan2Radiology, St. Marianna University School of Medicine, Kawasaki, Kanagawa, Japan3Surgery, Shohnan-chuoh Hospital, Fujisawa, Kanagawa, Japan

Received: January 6, 2010; Accepted: February 23, 2010Corresponding author: Koji Ando MD. Chest Surgery, St. Marianna University School of Medicine, 2-16-1 Sugao, Miyamae-ku, Kawasaki, Kanagawa 216-8511, JapanEmail: andy@marianna-u.ac.jp©2011 The Editorial Committee of Annals of Thoracic and Cardiovascular Surgery. All rights reserved.

Purpose: Pulmonary artery coil embolization (PACE) is increasingly utilized to treat pulmo-nary arteriovenous malformations (PAVMs), but the long-term outcome of this treatment modality remains unclear. By evaluating the long-term outcome of patients at St. Marianna University Hospital treated with PACE, we wanted to see if PACE could effectively replace the surgical resection of PAVMs.Patients and Methods: We retrospectively evaluated 9 consecutive patients (4 males, 5 females; age range, 16-67 years; mean ± SD, 43.6 ± 18.7 years) who underwent PACE for PAVMs. Selective pulmonary artery angiography using Seldinger’s method was initially per-formed to identify the feeding arteries. This was followed by embolization using interlocking detachable coils and microcoils. Results: The procedure resulted in no severe complications. All treated patients were free from PAVM symptoms. A recurrence did not occur after PACE in 8 of 9 (88%) patients for 31 to 173 months (86 ± 51). Recanalization of the embolized malformation occurred after 3 months in one patient. This patient underwent an additional successful PACE without any further recurrences for 73 months.Conclusions: PACE is an organ-sparing therapy with satisfactory long-term results. It can safely replace the surgical resection of PAVMs.

Key words: arteriovenous malformation, coil embolization, intervention, malformation, pulmonary vessel

Introduction

A pulmonary arteriovenous malformation (PAVM) is a relatively rare congenital disease caused by abnormal

communications between the pulmonary arteries and pulmonary veins.1) About 70% of patients with PAVMs in western countries have hereditary hemorrhagic telangi-ectasia, which is transmitted in an autosomal dominant inheritance.1) The rate is lower in Asians than in people of European descent. Patients with PAVMs usually have multiple lesions as a systemic disease. The malformations are made of thin-walled vascular channels and connec-tive tissue stroma. A PAVM lesion may be a large single sac, a plexiform mass of dilated vessels, or a tortuous direct communication between arteries and veins. Depending on the size and number of lesions, symptoms vary from totally absent to severe dyspnea with cyanosis due to right-to-left blood shunt.2) Dissemination of thrombi to the brain causes brain abscesses, especially for the hereditary type of PAVM.3) Rupture of a large

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PAVM can induce a life-threatening massive pulmonary hemorrhage.4, 5) Therefore, curative treatment is neces-sary, even for subclinical cases.

Surgical resection or exteriorization of a vascular fis-tula has long been the therapy for PAVMs. Minor lung resection, such as excisional resection or wedge resection, may be enough for a cure when a PAVM is solitary, small, and located in the peripheral regions of the lungs. However, a larger resection (including lobectomy or seg-mentectomy) is often necessary, depending on the size, number, and location of lesions.6)

Embolotherapy—including balloon embolization and pulmonary artery coil embolization (PACE)—has been increasingly utilized recently to treat PAVMs. As an organ-sparing therapy, it is initially successful, but the long-term outcome of this treatment modality needs to be determined.7) By evaluating retrospectively the long-term results of PACE performed at St. Marianna Hospi-tal, we could determine whether PACE can replace sur-gery as a treatment for PAVMs.

Patients and Methods

PatientsBetween June 1993 and December 2004, nine consecu-

tive patients with PAVMs were treated with PACE at St. Marianna University Hospital. They were 4 males and 5 females and ranged in age from 16 to 67 years (mean ± SD, 44 ± 19). The presenting signs or symptoms detected during physical check-up were dyspnea (1 patient), con-tinuing dry cough (1 patient), and nodular shadows on chest radiographs (7 patients). The patients’ Karnofsky performance status (PS) ranged from 0 to 1. All patients

received PACE to improve their presenting respiratory symptoms or to prevent future undesired events such as enlargement of the malformation, massive pulmonary hemorrhage, brain abscesses, or dyspnea. Prior to PACE, the patients underwent contrast-enhanced chest computed tomography (CT) and pulmonary artery angiography to identify the size, number, location and feeding arteries of the PAVM. The mean follow-up period of the patients was 89 months.

Pulmonary artery coil embolizationAfter applying local anesthesia around the right femo-

ral vein, and by using Seldinger’s method, we inserted a catheter toward the right ventricle for placement of the coil. Selective pulmonary artery angiography was used to measure the size of the feeding arteries. Then, one or two interlocking detachable coils (IDC) (Boston Scientific, Boston, MA)8, 9) were inserted into the malformation. The coils had a slightly larger diameter than that of the feed-ing artery. Then, fluorography was used for the addi-tional delivery of multiple Tornade® microcoils (Cook Medical, Bloomington, IN) that completely embolized the extended nidus (Fig. 1A and 1B). The size of the IDCs ranged from 2 to 30 mm, and the size of the Tor-nade® microcoils ranged 3 to 10 mm. Angiography con-firmed the occlusion of the feeding arteries at the end of the procedure. During the procedure, ECG monitoring was continuous, and the patients received intravenous fluids and antibiotics to prevent infection.

Follow-up of the patientsThe routine follow-up evaluations of the patients took

place at the outpatient department after discharge. Every

Fig. 1A: Interlocking detachable coils used for the embolization of pulmonary arteriovenous malformations. B: Tornade® microcoils used for the embolization of pulmonary arteriovenous malformations.

A B

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three months for one year, we evaluated the patients’ chest radiographs and contrast-enhanced chest CTs to detect enlargement or recanalization of the embolized PAVMs.10) After one year, patients had a routine follow-up evaluation every 6 months or annually.

StatisticsDifferences between the PaO2 values before and after

PACE were analyzed using the Student’s t-test. A p value <0.05 was considered significant.

Results

Profiles of the patients and the long-term follow-up results are shown in Table 1. Two patients had multiple lesions and seven patients had a single lesion. Only one patient (No. 6) had Osler-Weber-Rendu disease. There were no severe complications resulting from the proce-dure (Fig. 2A–2C). Dislocation of the coils occurred in two patients (No. 1 and No. 2) during the procedure. The microcoil in the right ventricle unexpectedly dislodged in the first patient and migration of the microcoil to the gastroduodenal artery occurred in the second patient. The dislodged coil in the right ventricle was immediately removed through the catheter, but the migrated coil in the abdominal artery was allowed to remain at the site because the patient had no symptoms and no further

migration occurred. The arterial oxygen partial pressure (PaO2) improved

dramatically after PACE therapy in 6 patients. The PaO2 was not measured in 3 patients. The average PaO2 in patients before treatment was 70.3 ± 19.0 Torr. This increased to 86.6 ± 20.8 Torr after PACE therapy (p <0.03, Fig. 3).

Most patients were discharged from the hospital uneventfully one to two days after treatment. Two patients (No. 1 and No. 2) had multiple PAVMs and required a longer hospital stay to undergo 2 to 3 staged PACE treatments. Recanalization of the PAVM occurred in one patient (No. 3) after 3 months. This patient received additional microcoils as a final embolization. Two patients (No. 1 and No. 3) died from other diseases at 72 months and 137 months after discharge. All patients were free from PAVM symptoms and recurrences did not occur from 31 to 173 months after PACE therapy (the average was 85.9 ± 50.7 months).

Discussion

PAVM usually generates a right-to-left blood shunt in which pulmonary oxygenation of the blood does not occur, resulting in hypoxemia and cyanosis.11) Surgical resection of the arteriovenous fistula can be the most radi-cal therapy. However, a complete resection is sometimes

Table 1 Long-term results of pulmonary artery coil embolization for pulmonary arteriovenous malformations

PAVM FA Number of coils used PaO2 (mmHg)

Patientnumber Age Sex Loca-

tion

Maximum diameter

(mm)

Num-ber

Maximum diameter

(mm)

Num-ber IDC Micro-

coils

Before embo-lization

After embo-lization

Follow-up period (months)

Recanalization of PAVM or associated symptoms

1 67 F BLLs 25 6 6 6 6 6 46.9 60.1 72 None

2 56 F BLLs+LS5 12 3 5 3 3 3 63.7 66.8 173 None

3 58 F RS3 30 1 6 1 2 3 ND ND 172

Recanalization occurred 3 months

after the initial PACE necessitat-ing an additional

PACE

4 60 M RS1 35 1 5 2 2 12 63.6 80.5 54 None5 34 M LS6 15 1 6 1 1 3 78.7 95.5 54 None6 44 F RS6 28 1 10 1 1 8 65.7 106.7 72 None7 16 M RS6 30 1 6 1 1 2 ND ND 96 None8 41 F RS2 10 1 4 1 1 2 ND ND 31 None9 16 M LS3 17 1 6 1 1 1 103.1 110.0 73 None

BLLs, bilateral lower lobes; F, female; FA, feeding artery; L, light; M, male; PACE, pulmonary artery coil embolization; PAVM, pulmonary arteriovenous malformation; R, right; S, segment;；ND,；not determined

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A B

C

Fig. 2A: The pulmonary angiography shows an arteriovenous malformation in the right pulmonary segment (S6) in patient No. 6 who had dyspnea due to right-to-left shunt. B: In this patient, one interlocking detachable coil and additional multiple microcoils applied to the feeding artery completely abolished the blood flow. Dyspnea due to shunt effects disappeared immediately after the embolization.C: A chest radiograph taken 48 months after the arterial embolization shows a calcified lesion at the embolized area.

Fig. 3 A comparison of the average arterial oxygen partial pressure of the patients before (70.3 ± 19.0 Torr) and after (86.6 ± 20.8 Torr) coil embolization ( p <0.03). The signif icant improvement resulted from abolishing the right-to-left blood shunt created by the malfor-mations.

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difficult for multiple lesions. In addition, when a major lung resection (including lobectomy) is required, a post-surgical loss of lung function may become a problem.12) Since the early 1980s, interventional therapy by embo-lization is gradually replacing surgery.13, 14)

The angioarchitecture of the malformation is impor-tant for embolization because a cure requires the occlu-sion of all feeding arteries.15) The treatment indication for asymptomatic PAVM is still unclear. However, several authors have recommended embolotherapy for lesions with a feeding artery diameter of greater than 3 mm to prevent further complications.7, 16, 17) The diameter of the feeding artery in patients with PAVM was larger than 3 mm and ranged between 4 to 10 mm in size.

The recurrence of a fistula after PACE is a major con-cern about the efficacy of this treatment modality.18) In a long-term follow-up study, Lee et al.19) reported that 52 large PAVMs in 38 of 45 patients (84%) were cured by the first embolotherapy. Persistent PAVMs in the 7 remaining patients were successfully treated by a second or a third procedure. In this study, one patient (12%) had a recurrence, but an additional one-time embolization cured it. Thus, embolotherapy seems to obtain permanent occlusion of a PAVM in the majority of patients, and pat-ency due to recanalization or accessory artery growth can be easily detected and treated.

Mager et al.20) reported that periprocedural complica-tions of embolotherapy occurred in 8% of sessions in 112 patients with PAVMs. Adverse events after embolization were migration of an embolic device, transient ischemic attack (TIA), angina pectoris, and early cerebral infarc-tion. In these patients, dislocation of microcoils occurred during the procedure, but no serious complications were observed during each of the 31-month follow-up periods.

In summary, since PAVMs did not recur after PACE therapy in 8 of 9 (88%) patients during the long-term fol-low-up period, we believe this treatment modality can replace surgical resection as an organ-sparing treatment in most patients. PACE for PAVMs is efficacious and tol-erable in the majority of patients. However, as we demon-strate, routine follow-up is required since the recanaliza-tion of PAVMs or enlargement of untreated PAVMs occurring after treatment cannot be neglected for many years.

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