arteriovenous malformation: a rare cause of cyanosis in childhood
Mottaghi 1, Mahdi Kahrom 2,& , Mohammad Hassan
Nezafati 2, Hadi Kahrom2
1Division of Cardiology,
Department of Pediatrics, Imam Reza Hospital, 2 Department of
Cardiac Surgery, Imam Reza Hospital, Mashhad University of Medical Sciences,
Department of Cardiac Surgery, Imam Reza Hospital, Mashhad
University of Medical Sciences, Mashhad, Iran
Pulmonary arteriovenous malformations (PAVMs) are caused by
abnormal communications between pulmonary arteries and pulmonary veins, which
are most commonly congenital in nature. Although these lesions are quite uncommon,
they are an important part of the differential diagnosis of common pulmonary
problems such as hypoxemia, pulmonary nodules and cyanosis. PAVM is a rare
disorder with an incidence of 2-3 per 1000000 population .
It occurs twice as often in women as in men, but there is a male predominance
in newborns . Around 10% cases of PAVM are identified in infancy or
childhood, followed by a gradual increase in the incidence through the fifth
and sixth decades. Approximately 70% of the cases of PAVM are associated with
hereditary hemorrhagic telangiectasia (HHT). Conversely, about 15 to 35%
of patients with HHT have PAVM . PAVMs may cause hypoxemia and dyspnea due
to right to left shunting, but remain frequently undiagnosed. This
intrapulmonary malformation is described in two patients who presented with
Patients and case reports
A 6-month-old male infant presented to our hospital with cardiac
murmur and progressive cyanosis of one day. He was born at term after a normal
pregnancy and without prenatal complications. His family history was
unremarkable and specifically negative for cardiopulmonary disorders. He had
dusky color, but was relatively well and thriving. His mother related a history
of orthodeoxia with an increase in cyanosis when her infant is embraced and
decrease in cyanosis when lying on the back.
Cardiovascular examination revealed bounding peripheral pulses
in both upper and lower limbs, normal first and second heart sounds and a
continuous machinery murmur, which were heard at the left upper sternal border
space, suspicious of patent ductus arteriosus (PDA). Chest examination revealed
normal vesicular breathing, equal on both sides of the chest. The examination
of abdomen, central nervous system, skin and mucosa did not reveal any
Investigations showed arterial blood gases (room air) to have pH
of 7.23, PCO2 37mmHg, HCO3 17mmol/L, PO2 34 mm
Hg and O2 saturation 61%. Chest X-ray showed normal cardiac size and
clear fields in both lungs. Electrocardiogram showed normal sinus rhythm, normal
QRS axis, and no right ventricular hypertrophy. Other laboratory findings
showed hemoglobin levels of 11.8 g/dl with normal methemoglobin of 1.2%.
Echocardiography confirmed the PDA in our patient, but was not a
rationale for his diagnosed cyanosis. Our patient underwent video assisted
thoracoscopic surgery (VATS) for closure of PDA. To our expectation, as the PDA
closure did not resolve the progressive cyanosis and early clubbing, contrast
echocardiography study was performed, suggesting the presence of PAVM with
significant right to left shunt, as evidenced by rapid filling of the left
atrium with dissolved bubbles. Cardiac catheterization performed which
revealing the pulmonary arteriovenous malformation in postero-basal segment of
lower zone of the left lung (Figure 1), with normal pulmonary artery pressure
of 15/5mmHg (mean 10). Oxygen saturation of the aorta was 64%, which made him a
candidate for surgical versus catheter-based intervention. Percutaneous
transcatheter embolization of PAVM with spring coils was performed in this
patient with significant improvement in systemic oxygenation and excellent
result in 5 years follow up.
A 10-year-old girl was referred to the department of pediatric
cardiology with severe cyanosis. There was a history of bluish discoloration of
fingers and lips for the past 5 years. There was no history of breathlessness.
On examination, the patient was thin built; peripheral pulses were normal,
blood pressure 95/72 mmHg, with normal S1 and S2. There was central cyanosis in
lips and nails and grade 2 clubbing was present. There was no evidence of
mucocutanious telangiectasis. Examination of cardiopulmonary and nervous system
was essentially normal. Hemoglobin was 16.8g/dl with normal methemoglobin of
2%. Chest X-ray and pulmonary function tests (PFTs) were reported to be normal
by pulmonologists. Arterial blood gas analysis at room air showed pH 7.20, PO2
58.8 mmHg, PCO2 40.3 mmHg and oxygen saturation of 88%.
Contrast echocardiographic study was performed, but did not
reveal any significant anomaly. Cardiac catheterization was performed and
injection of contrast media in the main pulmonary artery showed immediate
opacification of the left atrium and small haziness in the left lung. Selective
injection of contrast media in left pulmonary artery demonstrated the PAVM in
superior lingula of the left lung (Figure 2). Successful transcatheter
embolization was attempted in the patient and resulted in resolution of
cyanosis during 6 moths follow up.
Pulmonary arteriovenous malformation (PAVM) is a rare
cardiovascular anomaly. Most cases are congenital, frequently related to
hereditary hemorrhagic telangiectasia (HHT), an autosomal dominant disorder.
Abnormal communications between blood vessels of the lung may also be found in
a variety of acquired conditions such as hepatic cirrhosis, schistosomiasis,
mitral stenosis, trauma, actinomycosis, Fanconiís syndrome and metastatic
thyroid carcinoma [4,5]. Fifty-three to seventy percent of PAVMs are found in lower
lobes, 75% of patients have unilateral disease, 36% have multiple lesions,
and half of those with multiple lesions have bilateral disease .
PAVMs are supplied by pulmonary arteries in about 95% of cases, and by systemic
arteries less frequently .
Symptoms in early life may vary from being totally absent to severe
cyanosis, congestive heart failure and even fulminant respiratory failure .
Symptoms related to PAVM often develop between the 4th and 6th decades.
Progression of PAVMs is often noted during pregnancy . A progressive
increase in cyanosis is often noted because of the opening of new or
enlargement of the existing fistula, and development of polycythemia.
Haemoptysis and haemothorax may occur, especially in patients with HHT and in
pregnant women. Neurologic sequels are quite common and may occur in up to 33%
of patients with HHT . The diagnosis of PAVM should be suspected in patients with
any of the following presentation: (1) one or more pulmonary nodules associated
with typical radiographic findings, (2) mucocutaneous telangiectasis, and (3)
hypoxemia, polycythemia, clubbing, cyanosis, cerebral embolism, or brain
Chest X-ray may show one or more rounded multilobular opacities
when the fistulas are large enough. Cardiomegaly may rarely be present when the
fistulas are very large and cause a hyperdynamic state. However, the chest film
is not a very sensitive diagnostic modality. Pulse oxymetry is usually
abnormal, with various degrees of desaturation but it may not detect small
fistulas. The most sensitive non-invasive screening test for PAVMs, either in
context of complex congenital heart disease or in patients with HHT, is
contrast echocardiography . Radionuclide testing using Tc99m labeled
albumin microspheres is also a useful test, which can provide a quantitative
measurement of the right to left shunt by measuring the fraction of the
injected dose of microspheres reaching the kidneys . Chest computed
tomography may demonstrate PAVMs quite accurately. Recently, contrast enhanced
magnetic resonance angiography was compared to helical CT. It was found quite
sensitive (75%) and very specific (100%). All significant PAVMs with a feeding
vessel diameter>3mm were detected. Thus, contrast enhanced magnetic
resonance angiography seems to be a very useful nonionizing and noninvasive
procedure for the diagnosis and exact anatomic localization of PAVMs .
Despite advances in the techniques mentioned thus far, contrast pulmonary
angiography remains the gold standard in diagnosing PAVM, and is usually
necessary if resectional or obliterative therapy is being considered .
Pulmonary artery pressures are either normal or low because of the decreased
pulmonary vascular resistance, especially when the fistulas are large or
Three forms of management are available for the various types of
PAVMs: (1) transcatheter embolization therapy (using different devices such as
coils, detachable balloons, and various devices designed for occlusion of
atrial septal defects and patent arterial ducts), (2) surgical approach,
including lobectomy, segmentectomy or fistulectomy, redirection of hepatic
venous flow to the pulmonary circulation, and heart or heart/lung
transplantation and (3) medical therapy (including pharmacologic management) in
a few cases.
The diagnosis of PAVM should be considered in infants with
severe cyanosis without structural cardiac lesions or pulmonary hypertension,
after excluding other causes of cyanosis, such as parenchymal lung disease and
the rare methemoglobinemia, as described before. A high index of suspicion is
required for a successful echocardiographic diagnosis of PAVM in a cyanotic
infant with the use of contrast echocardiography. Pulmonary angiography is
mandatory whenever a diagnosis of PAVM is suspected in order to confirm the
diagnosis and a precise identification of the number and location of all
lesions before embolization or surgical intervention is undertaken.
authors declared they have no conflicts of interest.
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