Pulmonary Arteriovenous Fistulae Treatment & Management

The role of hormonal therapy in patients with recurrent bleeding secondary to GI or nasopharyngeal mucosa has been reported in the literature. Findings from these small studies have suggested a modest benefit. Anecdotal reports have also suggested successful treatment of epistaxis and GI hemorrhage by using danazol, octreotide, desmopressin, and aminocaproic acid.

Definite therapy for pulmonary arteriovenous malformations (PAVM) involves therapeutic embolization or surgical resection.

Catheter intervention - Therapeutic embolization

Embolization therapy (ie, embolotherapy) is a form of treatment based on occluding the feeding arteries to a pulmonary arteriovenous malformation.

The first successful case of embolotherapy of a pulmonary arteriovenous malformation was reported in 1977 and involved the use of handmade steel coils. Since then, embolization with coils and/or detachable balloons has been reported in numerous series of more than 250 patients. Other embolic materials include polyvinyl alcohol, cotton wool coils, and stainless steel coils.

Indications for embolotherapy include the following:

• Progressive enlargement of the lesions
• Paradoxic embolization
• Symptomatic hypoxemic
• Feeding vessels of 3 mm or larger

The technique of coil embolotherapy involves the localization of the pulmonary arteriovenous malformation by means of angiography, followed by selective catheterization of the feeding artery. A steel coil is advanced through the catheter and placed distal to any branch of the vessel. Sometimes, more than 1 coil is required to completely occlude the vessel. Multiple pulmonary arteriovenous malformations can be embolized in a single session.

The second embolotherapeutic technique uses detachable balloons. After localization of a pulmonary arteriovenous malformation, a balloon catheter is exchanged over a guidewire and positioned at the neck of the pulmonary arteriovenous malformation.

Follow-up CT scans obtained 1 or more years after embolotherapy indicate that 96% of pulmonary arteriovenous malformations are either undetectable or reduced in size. These findings occur secondary to thrombosis and retraction of the aneurysmal sac after successful vascular obstruction.

In one series of 45 patients who underwent embolotherapy of large (>8 mm) pulmonary arteriovenous malformations, 98% of the pulmonary arteriovenous malformations were occluded during the initial attempt, 84% of patients remained successfully treated, and 16% of patients had persistent pulmonary arteriovenous malformations. The persistence of the pulmonary arteriovenous malformations was caused by recanalization of initial successful occlusion in 5 patients, and it was caused by interval growth of new feeding vessels in 3 patients. All 8 of the persistent pulmonary arteriovenous malformations were successfully occluded during a second procedure, although one pulmonary arteriovenous malformation required a third procedure for permanent occlusion.

A summary of 10 published series of therapeutic embolization for pulmonary arteriovenous malformation documented an average success rate of 98.7%. Balloon embolotherapy is generally used in pulmonary arteriovenous malformations with feeding vessels larger than 7-10 mm.

Embolotherapy appears to be the treatment of choice because major surgery, general anesthesia, and loss of pulmonary parenchyma may be avoided.^[6] Embolotherapy is a clear choice in patients with multiple or bilateral pulmonary arteriovenous malformations or in patients who are poor surgical candidates.

Postcatheterization precautions include hemorrhage, vascular disruption after balloon dilation, pain, nausea and vomiting, and arterial or venous obstruction from thrombosis or spasm.

Possible complications include rupture of blood vessels, tachyarrhythmias, bradyarrhythmias, and vascular occlusion.

Pleuritic chest pain is the most common complication and is observed in 12% of patients. This pain usually responds well to analgesics. Radiographic evidence of pulmonary infarction is observed in 3% of patients.

Air embolism during embolotherapy is suspected in 4.8% of patients; they developed transient symptoms such as angina, perioral paraesthesias, and bradycardia.

Device migration has been reported in 1.2% of embolization attempts.

Long-term follow-up evaluation has shown potentially serious complications in 2% of patients treated with embolotherapy.

Symptomatic recanalization was observed with 0.5% of procedures.

A new or increased pulmonary hypertension after embolization has been reported in several patients. Incidence of complication appears to be higher when the feeding vessels of more than 8 mm were occluded.

Until 1977, surgery was the only method of treatment. Ligation, local excision, segmentectomy, lobectomy, or pneumonectomy was performed in most cases. The reported perioperative mortality rate from surgery varied from 0-9%. Postoperative follow-up evaluation shows recurrence or enlargement of the pulmonary arteriovenous malformation in as many as 12% of patients. Surgery is the best choice for patients with an untreatable allergy to the contrast material.

Indications

Indications for surgery are progressive pulmonary arteriovenous malformation enlargement, paradoxic embolization, and symptomatic hypoxemia. The treatment of all pulmonary arteriovenous malformations with feeding vessels 3 mm or larger is also recommended.

Techniques

Standard thoracic surgical techniques, such as ligation of pulmonary arteriovenous malformation, local excision, segmentectomy, lobectomy, or pneumonectomy, have been performed. In some cases, staged bilateral thoracotomies are performed. Recently, video-assisted thoracoscopic resection of a small pulmonary arteriovenous malformation has been performed.^[7]

Results

Postoperative follow-up evaluation shows recurrence or enlargement of another pulmonary arteriovenous malformation in as many as12% of patients. During a follow-up evaluation performed 8 years after surgery, one case of stroke and one case of mortality related to pulmonary arteriovenous malformation occurred. Reports also suggest the development of pulmonary arterial hypertension. Moderate surgical techniques for the resection of pulmonary arteriovenous malformations are associated with a negligible mortality rate, but they are associated with the morbidities that accompany a thoracotomy.

Complications

According to various reported series, the perioperative mortality has varied from 0-9.1%. Most of the studies that reveal high mortality rates were reported before 1960. Postoperative morbidities have been well reported.

Activity

Patients with pulmonary arteriovenous malformations have reduced exercise tolerance.

Other

Long-term clinical and imaging results of technically successful pulmonary arteriovenous malformations embolization in 150 patients were reviewed. Four hundred and fifteen pulmonary arteriovenous malformations were occluded during 205 procedures. Complications included respiratory symptoms (n = 13), cerebral ischemia (n = 4), brain abscess (n = 5), hemoptysis (n = 3), and seizure (n = 1). Imaging showed pulmonary arteriovenous malformation involution in 97% of embolized lesions and 11 residual lesions (2.8%) in 10 patients (6.9%). The other 97 previously small pulmonary arteriovenous malformations had enlarged to a significant size in 28 patients (18%). These data emphasize ongoing clinical and anatomic evaluation after pulmonary arteriovenous malformation embolization.^[8]

Large pulmonary arteriovenous fistulas (PAVFs) present significant difficulty for transcatheter treatment. However, initial experience with Amplatzer duct occluder (ADO) looks promising. One case series reported 5 patients, aged 3-73 years, with large PAVFs who underwent successful transcatheter closure with ADO. No complications occurred and the patients' arterial oxygen saturation and exercise tolerance improved. Thus, transcatheter closure of large PAVFs with the ADO is effective and can eliminate the need for surgical intervention. The newly designed Amplatzer vascular plug is undergoing clinical trials.^[9]