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Congenital pulmonary arteriovenous fistula


Historical Notes

In 1897, the British Medical Journal published a necropsy description of congenital pulmonary arteriovenous fistulae and, four decades later, the anomaly was recognized in a living subject. In 1865, Babington called attention to familial epistaxis, and in 1876, Legg described recurrent epistaxes and cutaneous telangiectasia in three generations. Twenty years later, Rendu published his classic description of familial epistaxes and telangiectasia (cutaneous angiomata) of the nose, cheeks, and upper lip. In 1901, Osler reported “ On a family form of recurring epistaxis associated with multiple telangiectases of the skin and mucous membranes ,” and in 1907, Weber reported “ Multiple hereditary developmental angiomata (telangiectases) of the skin and mucous membranes associated with recurring haemorrhages .” In 1909, Hanes referred to the disorder as hereditary hemorrhagic telangiectasia , , but the eponym Rendu, Osler, Weber remains in use without the inclusion of Legg, and with no consensus about the most appropriate sequence of names. , The diagnosis of hereditary hemorrhagic telangiectasia (HHT) is made clinically by the Curaçao criteria , which were established in 1999 by the Scientific Advisory Board of the HHT Foundation International. The criteria include recurrent epistaxis; telangiectases of the lips, oral cavity, fingers, and nose; gastrointestinal telangiectasia; and pulmonary, hepatic, cerebral, or spinal arteriovenous malformations. , ,

Anatomic considerations

Pulmonary arteriovenous fistulae are the result of an embryonic fault in the vascular complex that is responsible for the development of pulmonary arteries and veins. The fistulae can be solitary or multiple, unilateral or bilateral, or minute and diffuse throughout both lungs. Approximately 75% of congenital pulmonary arteriovenous fistulae involve the lower lobes or right middle lobe , ( Figs. 27.1–27.5 and – ), and usually occur without coexisting congenital heart disease. Isolated exceptions have been reported with left isomerism , (see Chapter 3 ) and with atrial septal defect (see Chapter 12 ). Estimated minimum prevalence is 1:10,000 births.

Fig. 27.1, (A) X-ray of a 21-year-old male with a congenital right lower lobe pulmonary arteriovenous fistula (thick arrow) . The lobulated density is connected to the hilus (thin arrow) by dilated vessels that enter and leave the fistula. The x-ray is otherwise normal. (B) Angiocardiogram showing the fistula (thick arrow) with its pulmonary arterial connection (thin arrow) .

Fig. 27.2, Pulmonary arteriogram from a 35-year-old female with a solitary left lower lobe congenital pulmonary arteriovenous fistula (AV Fistula) . An afferent (Aff.) channel enters the fistula, and an efferent (Eff.) channel leaves the fistula. LPA, Left pulmonary artery.

Fig. 27.3, Angiocardiogram from a 32-year-old male with congenital bilateral pulmonary arteriovenous fistulae of the right and left lower lobes (arrows) . Afferent and efferent vascular channels join and leave the fistula and are readily seen on the right. The left lower lobe fistula (arrow) is behind the cardiac apex, inviting a mistaken diagnosis of intracardiac origin. The heart size is normal.

Fig. 27.4, A 46-year-old female with pulmonary stenosis who has undergone previous surgical pulmonary valve replacement developed progressive cyanosis and was noted to have a pulmonary arteriovenous fistula on chest CT. Invasive angiography was then performed. (A) Anterior projection, selective angiogram in the distal right middle lobe pulmonary artery (PA) demonstrates brisk filling of a large and tortuous afferent limb (AL) with subsequent filling of two efferent limbs (ELs) that eventually enter the inferior and superior right sided pulmonary veins (PVs) . (B) Lateral projection of the same injection as A; note the anterior location of the arteriovenous malformation and the length of the afferent and efferent limbs. (C and D), Anterior and lateral projections of a selective PA injection after comprehensive coil occlusion of the AL demonstrates no residual flow. The patient’s systemic arterial saturation improved from 88% on room air to 94% on room air immediately following this intervention.

Fig. 27.5, (A) Close-up of the chest x-ray of a 26-year-old female with a single large left upper lobe pulmonary arteriovenous fistula (AV Fistula) . She had endured two brain abscesses. The solitary fistula and its afferent (Aff.) and efferent (Eff.) vascular channels are faintly seen. PT, Pulmonary trunk. (B) Contrast material selectively injected into the left pulmonary artery (LPA) visualized the afferent channel that entered the fistula and the efferent channel that left the fistula.

A fistula consists of either one or more relatively large vascular trunks, a thin aneurysmal sac, or a tangle of distended tortuous vascular channels ( Figs. 27.6 and 27.7 ; see also Figs. 27.1–27.5 ; see and ). The arterial supply is through enlarged tortuous branches of a pulmonary artery, and drainage is through dilated pulmonary veins (see Figs. 27.1–27.4 and 27.7 ). , Fistulous rupture results in hemorrhage into the pulmonary parenchyma or into the pleural space. Exceptionally, the arterial supply is from a bronchial, intercostal, anomalous systemic artery or a coronary artery (see Chapter 19 ). The fistula is then systemic arteriovenous rather than pulmonary arteriovenous. A rare anatomic variation consists of a congenital connection between a pulmonary artery and the left atrium, an anomaly in which an initial connection exists between a pulmonary artery and a pulmonary vein, but during vascular development the pulmonary vein becomes incorporated into the left atrium. Extralobar arteriovenous fistulae are represented by pulmonary sequestrations in which the arterial supply and venous drainage are systemic rather than pulmonary. Isolated congenital varicose pulmonary veins are rare and not the result of arteriovenous malformations.

Fig. 27.6, A 38-year-old male with complex single ventricle physiology who has undergone the Fontan operation and multiple intravascular interventions. The patient presents with worsening cyanosis. (A) Nonselective right pulmonary artery angiography demonstrating a right lower lobe arteriovenous malformation (AVM) fed by a long and tortuous afferent limb (AL) with one efferent limb (EL) faintly noted. (B) Complete occlusion of the AL and AVM with transcatheter coil embolization.

Physiologic consequences

The physiologic consequences of pulmonary arteriovenous fistulae depend on the amount of unoxygenated blood delivered through the malformation and on the size of the malformation, which tends to increase with age. , Although the volume of blood delivered through the fistula is sufficient to cause cyanosis, it is rarely sufficient to impose a physiologic burden (see Fig. 27.4 ). Pulmonary artery pressure is normal with rare exception. In experimental pulmonary arteriovenous fistulae, cardiac output and left ventricular stroke volume are increased, but in congenital pulmonary arteriovenous fistulae, blood flow through the malformation is increased while flow through uninvolved lung decreases by a comparable amount. Accordingly, the net volume of blood reaching the left side of the heart is little if at all affected, so left ventricular stroke volume and cardiac output remain normal or nearly so. Rarely, a large pulmonary arteriovenous malformation imposes an excess volume load on the left side of the heart and induces congestive heart failure ( Fig. 27.8 ).

Fig. 27.8, A 3-D reconstruction of an invasive rotational right pulmonary artery angiogram viewed here from a right anterior oblique projection. There is a large pulmonary arteriovenous malformation (AVM) fed by an afferent limb (AL) coming off the right middle lobe pulmonary artery (PA) segment. Note the large efferent limb (EL) connected to a right pulmonary vein (PV) .

Blood flow through pulmonary arteriovenous fistulae is affected by mechanical factors. Flow through lower lobe fistulae is augmented in the upright position because of increased perfusion of dependent portions of the lungs. A decubitus position compresses the dependent lung and reduces blood flow through an ipsilateral fistula. A case in point was a large pulmonary arteriovenous fistula in an adult female that was causing progressive cyanosis; coil embolization of the afferent limb of the fistula occluded the vessel, immediately decreasing the cyanosis (see Fig. 27.4 and and ). Elevation of the diaphragm during pregnancy can compress a lower lobe fistula and abolish the accompanying murmur which reappears after delivery.

Acquired pulmonary arteriovenous fistulae are occasional sequelae of cavo-pulmonary shunts, especially Glenn shunts ( Fig. 27.9 ; see also Fig. 27.6 ). , Acquired fistulae occur in children with hepatic cirrhosis and portal hypertension, especially with biliary atresia and right isomerism , (see Chapter 3 ), and regress after liver transplantation. Large hepatic arteriovenous fistulae sometimes occur without pulmonary arteriovenous fistulae in Rendu-Osler-Weber disease. Hepatic, cerebral, and pulmonary arteriovenous fistulae may coexist.

Fig. 27.9, (A) Selective right lower lobe pulmonary artery angiogram (anteroposterior projection) in a 23-year-old with single ventricle physiology who had undergone a prior Fontan operation and attempted yet unsuccessful coil embolization of pulmonary arteriovenous malformations (PAVMs) . Note the continued brisk flow from the pulmonary artery (PA) via multiple afferent limbs (ALs) to the PAVMs with subsequent filling of an efferent limb (EL) to which one coil had embolized. (B) Transesophageal echocardiogram performed at the time of cardiac catheterization. Right PA agitated saline injection reveals 4+ shunting to the left atrium and subsequently to the single left ventricle (LV) . LA, Left atrium.

In 1917, telangiectasia and epistaxes were reported in a patient who died of massive hemothorax and at necropsy had three pulmonary arteriovenous fistulae. The association of hemorrhagic telangiectasia with pulmonary arteriovenous fistulae has been amply confirmed. , , , Hereditary hemorrhagic telangiectasia is an autosomal dominant vasculopathy. Clinical diagnostic criteria have changed remarkably little over the last century.

Pulmonary arteriovenous fistulae occur in 5% to 30% of patients with telangiectasia, and telangiectasia occurs in 30% to 60% of patients with pulmonary arteriovenous fistulae. Incidence of pulmonary arteriovenous fistulae with telangiectasia is 1:50,000 with autosomal dominant transmission and a 20% mutation rate. The mucocutaneous lesions are tiny, localized arteriovenous fistulae composed of thin, dilated vascular membranes with a layer of endothelium and no muscular or elastic coat. , The lesions are fragile and rupture easily. Telangiectasia are found on the skin, the lips ( Fig. 27.10 ), the nasal, oral, and vaginal mucous membranes, beneath the nails, and in the gastrointestinal tract, liver, central nervous system, kidney, and retina. ,

Fig. 27.10, X-ray of a 6-month-old cyanotic female with a congenital right lower lobe pulmonary arteriovenous fistula that faintly revealed itself (paired arrows) . Mucocutaneous telangiectasia was not identified. Cyanosis disappeared after coil embolization.

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