Pulmonary vascular manifestations of hereditary hemorrhagic telangiectasia (rendu-osler disease)

Hereditary hemorrhagic telangiectasia (HHT) or Rendu-Osler-Weber disease is a genetic disorder with autosomal dominance and variable penetrance, characterized by epistaxis, telangiectasia and visceral manifestations of the disease. The estimated minimal prevalence is 1/10,000 inhabitants. The diagnosis is established on clinical criteria, and may be further confirmed by the identification of causative mutations in either the ENG or the ACVRL1 gene coding for endoglin and ALK1, respectively. Pulmonary vascular manifestations of HHT include pulmonary arteriovenous malformations (PAVMs; especially in patients with ENG mutations) and less frequently pulmonary hypertension (especially in patients with ACVRL1 mutations). In 15-33% of patients with HHT, PAVMs consist of abnormal communications between pulmonary arteries and pulmonary veins, causing right-to-left shunting, and thus, frequently hypoxemia and dyspnea on exertion, although PAVMs may remain asymptomatic and frequently undiagnosed unless complications occur. PAVMs result in severe and frequent complications often at a young age, which may reveal the diagnosis, e.g. transient ischemic attack and cerebral stroke (10-19% of patients), systemic severe infections and abscesses (including cerebral abscess in 5-19% of patients), and rarely massive hemoptysis or hemothorax. Infections in HHT are related to the right-to-left shunting that bypasses the pulmonary capillaries and facilitates the passage of septic or aseptic emboli into the systemic and especially cerebral circulation, and potentially to minor defects in innate immunity. Treatment of PAVMs based on transcatheter coil vaso-occlusion of the feeding artery significantly decreases right-to-left shunting, hypoxemia and dyspnea on exertion, and reduces the risk of systemic complications. Long-term follow-up is warranted after transcatheter vaso-occlusion of PAVMs due to frequent recanalization of treated PAVMs and development or growth of untreated PAVMs. Patients with HHT should be informed of the risk of PAVM and potentially severe complications occurring in heretofore asymptomatic subjects. All adult patients with HHT should be proposed systematic screening for PAVM, by contrast echocardiography (preceded by anteroposterior chest radiograph) or computed tomography of the chest. Pulmonary hypertension is rare in HHT, and may be due either to systemic arteriovenous shunting in the liver increasing cardiac output or be clinically and histologically indistinguishable from idiopathic pulmonary arterial hypertension. Pulmonary hypertension is detected by systematic examination of right cardiac cavities and tricuspid regurgitation flow at echocardiography, and the diagnosis is established by right heart catheterization.     

Prevalence of pulmonary arteriovenous malformations (PAVMs) and occurrence of neurological symptoms in patients with hereditary haemorrhagic telangiectasia (HHT)

BACKGROUND: Hereditary haemorrhagic telangiectasia (HHT) is a dominantly inherited disease. HHT is characterized by a wide variety of clinical manifestations, including pulmonary arteriovenous malformations (PAVMs) and neurological symptoms. OBJECTIVE: To estimate (i) the prevalence of PAVM, and (ii) the occurrence of neurological symptoms in a geographical well-defined population of HHT patients. METHODS: HHT family members were invited to a clinical examination including registration of HHT manifestations, screening for pulmonary arteriovenous malformations and neurological evaluation. Two groups served as controls: (i) first-degree relatives without any signs of HHT; and (ii) age- and gender-matched controls. SETTING: Odense University Hospital. SUBJECTS: HHT patients identified in a cross-sectional family survey carried out in the County of Fyn, Denmark. RESULTS: Included in the study were 169 HHT family members representing 24 families. They included both HHT patients and their first-degree relatives. The criteria of HHT were fulfilled in 75 participants; of these, 59 had a screening procedure performed, and PAVMs were demonstrated at pulmonary angiography (PA) in 18. Seven of the HHT patients had a history of cerebral stroke, compared with none of their healthy first-degree relatives. CONCLUSION: The prevalence of PAVM was 24% amongst HHT patients. The study confirmed an increased prevalence of neurological symptoms amongst HHT patients; the odds ratio was estimated to be 7.6. In order to enable prevention of these complications, screening for PAVM should become an integral part of the medical care for HHT patients.     

Contrast echocardiography for detection of pulmonary arteriovenous malformations

BACKGROUND: Pulmonary arteriovenous malformations (PAVMs) lead to stroke, brain abscess, and hemorrhage in hereditary hemorrhagic telangiectasia (HHT). The current screening approach for PAVMs in HHT patients with chest radiograph (CXR) and oxygen shunt study has not been validated and is thought to be insensitive. We hypothesized that agitated saline contrast echocardiography (ECHO) would be a useful screening test for PAVMs. METHODS AND RESULTS: A total of 106 sequential HHT patients underwent screening for PAVMs with ECHO in a prospective study. If the test was positive, or if the CXR or shunt study suggested PAVMs, pulmonary angiography was performed. A positive ECHO was defined as appearance of bubbles in the left atrium after injection of agitated saline solution. A positive shunt study was defined as a partial pressure of oxygen in arterial blood <500 mm Hg while breathing 100% oxygen. The mean age was 41 years (range 15-80 years); 66% were female. Forty-four patients had positive ECHO. Forty-one of the 44 patients underwent angiography. Three patients declined further testing. Thirty-three of the 41 patients who underwent angiography were diagnosed with PAVMs. Of the 62 patients with a negative ECHO, 18 underwent angiography because of either a shunt study or CXR that was suggestive of PAVMs. Of these 18 patients, 2 had PAVMs. In the total population of 106 patients, 35 (33%) had PAVMs. ECHO was the only positive screening test in 11 of 35 (31%) patients. The diagnosis of PAVMs in these 11 patients would have otherwise been missed. CONCLUSIONS: ECHO is a useful screening tool for PAVMs in HHT.     

Multiple pulmonary arteriovenous malformations associated with hereditary hemorrhagic telangiectasia]

A 61-year old asymptomatic woman was admitted to our hospital for the examination of an abnormal shadow in the left lower lung lobe in 1978. Enhanced chest computed tomograms and pulmonary arteriograms revealed a pulmonary arteriovenous malformation (PAVM) composed of feeding artery and draining vein. The patient had suffered brain abscesses 3 times because of paradoxical emboli from PAVMs. A diagnosis of hereditary hemorrhagic telangiectasia (HHT) was made according to the criteria. The patient died of septic shock due to urinary tract infection by Candida albicans. We reviewed cases of PAVMs associated with HHT in the Japanese literature. In Japan, 126 HHT families and 144 HHT patients have been reported to date. PAVMs occur in approximately one-third of HHT patients in Japan. Twenty-four out of 45 patients (44.4%) had multiple PAVMs. We also discussed the diagnosis, complications, and treatment of PAVM-associated HHT.     

Clinical symptoms according to genotype amongst patients with hereditary haemorrhagic telangiectasia

BACKGROUND: Hereditary haemorrhagic telangiectasia (HHT) is a dominantly inherited disease, characterized by a wide variety of clinical manifestations, including epistaxis, gastrointestinal (GI) bleeding, pulmonary arteriovenous malformations (PAVMs) and neurological symptoms. HHT is a genetically heterogeneous disorder involving at least two loci; HHT 1 mapping to chromosome 9 q 34.1 (ENG) and HHT 2 mapping to chromosome 12 q 31 (ALK-1). OBJECTIVE: To evaluate and describe the diversity of clinical manifestations in a Danish population of HHT patients with known HHT 1 or HHT 2 subtype. DESIGN: Prospective clinical examination with genetic evaluation and follow-up. SETTING: Investigation centre was Odense University Hospital. All HHT patients in the County of Fyn were included. METHODS: HHT family members were invited to a clinical examination including registration of HHT manifestations, screening for PAVM and neurological evaluation. Blood tests were performed for analysis of disease-causing mutation, and clinical manifestations in the HHT subtypes were compared. The survival of the patients was studied in the follow-up period. RESULTS: Included in the study were 73 HHT patients representing 18 families. In 14 of the families we identified a disease-causing mutation. Thirty-nine patients (from 10 families) had HHT1 and 16 HHT patients from four families had HHT2. CONCLUSION: Amongst patients with HHT1 genotype the prevalence of PAVM was higher than amongst HHT patients with HHT2 genotype. HHT1 patients had experienced more severe GI bleeding than HHT2 patients. There was no significant difference in severity of epistaxis or age at debut. Finally the mortality over a 90-month observation period was not significantly increased.     

Malformaciones arteriovenosas pulmonares y complicaciones embólicas en pacientes con telangiectasia hemorrágica hereditaria

Patients with hereditary hemorrhagic telangiectasia (HHT) and pulmonary arteriovenous malformation (PAVM) face higher risk of embolic complications. It is not clear whether poor outcomes are related to PAVM severity or pulmonary symptoms. Furthermore, there is currently no available data on HHT patients in Argentina. We conducted a cross sectional study in a teaching hospital in Buenos Aires, Argentina. We describe baseline characteristics of HHT and compare the prevalence of embolic complications in patients with significant PAVM compared to patients without significant PAVM. One hundred and eight consecutive patients were included. Significant PAVM was defined as: contrast echocardiography grade 2 or greater; bilateral PAVM or feeding artery bigger than 3 mm; or previous PAVM treatment. Primary composite outcome was defined as: cerebrovascular accident, cerebral abscess or peripheral embolism. 20% of participants had embolic complications, the most frequent one was stroke. Embolic complications were associated with significant PAVM and respiratory symptoms.     

Pulmonary arteriovenous malformations: screening procedures and pulmonary angiography in patients with hereditary hemorrhagic telangiectasia.

BACKGROUND: Hereditary hemorrhagic telangiectasia (HHT) is a dominantly inherited disease with a high prevalence of pulmonary arteriovenous malformations (PAVMs). The first symptom of HHT may be stroke or fatal hemoptysis associated with the presence of PAVM. OBJECTIVE: To evaluate different screening methods applied for the identification of PAVMs. SETTING: Odense University Hospital. SUBJECTS: HHT patients with positive findings on contrast echocardiography (CE) who participated in a screening investigation and underwent pulmonary angiography (PA). METHODS: Different screening methods were evaluated against the results of PA. In a group of patients with positive findings on CE, we compared results of PA with the following: severity of dyspnea; results of pulse oximetry arterial oxygen saturation (SaO2) supine and upright; supine PaO2 in room air and while breathing 100% oxygen; size of arteriovenous shunt in supine position; chest radiograph; and intensity of contrast at CE. RESULTS: PA was performed in 25 HHT patients with positive findings on CE, 15 of whom had PAVM. Embolization therapy was recommended in 12 patients, and 3 patients had small PAVMs not accessible for therapy. In 10 patients, PAVM could not be demonstrated at PA. The sensitivity and specificity calculated for the screening procedures are as follows: 53% and 90%, respectively, for SaO2; 60% and 100%, respectively, for chest radiograph; 73% and 80%, respectively, for PaO2 in room air; 100% and 40%, respectively, for PaO2 breathing 100% oxygen; and 64% and 80%, respectively, for shunt measurement. CONCLUSION: Initial screening with CE followed by measurement of PaO2 while breathing 100% oxygen seemed to be the best screening procedure for identification of patients with PAVM. Screening with chest radiograph and pulse oximetry was shown to be insufficient.     

Pulmonary arteriovenous malformations, hereditary hemorrhagic telangiectasia, and brain abscess

Hereditary hemorrhagic telangiectasia (HHT) is a systemic angiodysplasia inherited as an autosomal dominant disease. Patients with HHT and pulmonary arteriovenous malformations (PAVMs) are at increased risk for brain abscess (BA), a potentially preventable condition as effective treatment for PAVMs is available. In a center dedicated to HHT, a history of BA was found in 6 out of 128 patients with a definite diagnosis: herewith, their histories are reported focusing on mistakes in the diagnosis and management of the disease. Patients with PAVMs and BA had a higher mean hemoglobin concentration (15.1 g/dl vs. 12.2 g/dl, p < 0.006 by Student's t test) compared to patients with PAVMs alone. Other clinical features (genetics, bacteriology, types of PAVMs, treatments, outcomes) are also discussed. Prompt diagnosis and screening for visceral involvement is pivotal for HHT patients and their relatives.     

A pulmonary right-to-left shunt in patients with hereditary hemorrhagic telangiectasia is associated with an increased prevalence of migraine

INTRODUCTION: Hereditary hemorrhagic telangiectasia (HHT) is a rare autosomal-dominant vascular dysplasia with a high prevalence of pulmonary arteriovenous malformation (PAVM). Recent studies report an increased prevalence of migraine in patients with a cardiac right-to-left shunt. The aim of our study was to evaluate whether there is also an increased prevalence of migraine in patients with a pulmonary right-to-left shunt (PAVM). METHODS: All patients with HHT referred to our hospital till April 2004 with or without PAVM and with or without migraine were included in the study. RESULTS: In total, 538 HHT patients (41.6% men; mean age +/- SD, 39.3 +/- 18.6 years) could be included. PAVM was present in 208 patients (38.7%; mean age, 39.3 +/- 17.6 years). Significantly more women were present in the PAVM subgroup compared to the non-PAVM subgroup, 65.4% vs 53.9% (p = 0.009). Migraine occurred in 88 patients with HHT, a prevalence of 16.4%. The prevalence of migraine in women with HHT was significantly higher compared to men, 19.4% vs 12.1%, respectively (p = 0.03) The prevalence of migraine in patients with PAVM was 21.2%, which was significantly higher then in patients without PAVM, 13.3% (p = 0.02). The occurrence of PAVM in the patients with migraine is significantly higher than in those without migraine, 50.0% vs 36.4%, respectively (p = 0.02). CONCLUSION: This study showed a higher prevalence of PAVM in patients with migraine and HHT. The right-to-left shunt due to the PAVM might play a causal role in the pathogenesis of migraine in patients with HHT. This needs to be determined in further studies.     

New definition and natural history of patients with diffuse pulmonary arteriovenous malformations: twenty-seven-year experience

BACKGROUND: Patients with diffuse pulmonary arteriovenous malformations (PAVM), a small but important subset of the PAVM population, have significant morbidity and mortality rates. METHODS: Thirty-six patients (21 female and 15 male) with diffuse PAVM from a cohort of 821 consecutive patients with PAVM were evaluated. Diffuse PAVM were categorized angiographically: involvement of one or more segmental pulmonary arteries in one or both lungs. Hereditary hemorrhagic telangiectasia (HHT) status, gender, presence or absence of large (> or = 3-mm diameter artery) focal PAVM, oxygen saturations, complications including hemoptysis, years of follow-up, and survival were tabulated. RESULTS: HHT was present in 29 of 36 patients (81%), and diffuse PAVM were more commonly bilateral (26 of 36 patients, 72%) than unilateral (10 of 36 patients, 28%) [p = 0.02]. Female gender was associated with bilateral diffuse PAVM (19 of 26 patients, 73%) [p = 0.01]. Focal PAVM were present in both groups but more commonly in patients with bilateral involvement (16 of 26 patients, 62%) [p = 0.02]. Initial oxygen saturations (pulse oximetry, standing) of patients with unilateral and bilateral diffuse PAVM were 87 +/- 7% and 79 +/- 8% (mean +/- SD), respectively (p = 0.02). The last or current values for patients with unilateral and bilateral involvement are 95 +/- 3% and 85 +/- 7%, respectively (p < 0.0001). Nine deaths occurred, and all were in patients with bilateral involvement. Deaths were due to hemoptysis of bronchial artery origin (n = 2), hemorrhage from duodenal ulcer (n = 1), spontaneous liver necrosis (n = 3), brain hemorrhage (n = 1), brain abscess (n = 1), and operative death during attempted lung transplant (n = 1). CONCLUSIONS: Patients with diffuse PAVM are a high-risk group, and yearly follow-up is recommended.     

Alveolar Exhaled Nitric Oxide is Elevated in Hereditary Hemorrhagic Telangiectasia

Patients with intrapulmonary shunt due to hepatopulmonary syndrome have diffuse pulmonary microvascular dilatation. Studies have shown that these patients have increased exhaled nitric oxide (NO) levels, suggesting that alveolar capillary NO production is increased. We speculated that alveolar capillary NO overproduction might have a similar mechanistic role in the development of shunting vessels, arteriovenous malformations, in hereditary hemorrhagic telangiectasia (HHT), in which 30–45% of patients have pulmonary arteriovenous malformations (PAVMs). Our objective was to determine if alveolar exhaled NO is elevated in patients with HHT compared to controls. We measured the alveolar fraction of exhaled NO (200 ml/s expiratory flow rate) in HHT subjects with and without a history of PAVMs and in healthy, nonsmoking controls with no known lung disease. We compared 58 HHT subjects to 49 healthy controls. Exhaled NO was significantly greater in HHT subjects (mean = 12.0 ppb, SD = 3.5) than in controls (mean = 10.5 ppb, SD = 3.2) (p = 0.02). We detected a significantly higher level of alveolar exhaled NO in subjects with HHT compared to healthy controls, suggesting that alveolar capillary NO production may be increased in HHT and may have a mechanistic role in PAVM formation.     

Contrast echocardiography remains positive after treatment of pulmonary arteriovenous malformations

STUDY OBJECTIVES: Pulmonary arteriovenous malformations (PAVMs) in patients with hereditary hemorrhagic telangiectasia (HHT) can cause hemorrhage, stroke, and cerebral abscess. Therapy consists of transcatheter embolotherapy (TCET) to occlude the PAVMs. Contrast transthoracic echocardiography (TTE) can be used to screen for PAVMs, but little is known about the performance of contrast TTE after TCET has been performed. Our objective was to determine the effect of the successful performance of TCET on the performance of contrast TTE, specifically, in what proportion of patients the findings of contrast TTE normalized or remained positive after the performance of TCET. DESIGN: Retrospective chart review. SETTING: HHT clinic at university teaching hospital. PATIENTS: Patients who have undergone TCET for the treatment of PAVMs. INTERVENTIONS: Patients were screened for PAVMs with a chest radiograph (CXR), oxygen shunt test (OST), and contrast TTE. Pulmonary angiography was recommended for patients with any positive findings on a screening test. PAVMs > or = 3 mm were occluded by TCET. Contrast TTE, OST, and CXR were performed approximately 1 month later. The results of contrast TTE before and after patients underwent TCET were compared. Measurements and results: Thirty-nine patients underwent contrast TTE prior to undergoing TCET, and 29 patients underwent contrast TTE both prior to and after undergoing TCET. In all patients, TTE findings were positive prior to TCET. All PAVMs with feeding vessels > or = 3 mm were successfully occluded based on completion angiography. After TCET, 48% of patients had no detectable residual PAVMs, and the remainder had small (ie, < 3 mm) residual PAVMs. Of the 29 patients, 90% had positive contrast TTE findings after undergoing TCET. In the subset of patients who had no residual PAVMs on the completion angiography, 80% had positive contrast TTE findings after undergoing TCET. CONCLUSIONS: In most patients, contrast TTE findings remain positive after they undergo TCET, even in patients without residual PAVMs seen on angiography. This may reflect residual PAVMs that are too small to visualize using angiography. These findings have important implications for the follow-up and management of HHT patients.     

Pulmonary arteriovenous malformations in patients with hereditary hemorrhagic telangiectasia

Pulmonary arteriovenous malformations (PAVMs) associated with hereditary hemorrhagic telangiectasia may cause severe cerebral complications that may be prevented by embolization therapy. We retrospectively compared the diagnostic value of noninvasive tests for the screening of treatable (amenable to embolization) PAVMs in a series of 105 patients, using chest computerized tomography (CT) and/or pulmonary angiography as a "gold standard." Patients had assessment of dyspnea, chest radiograph, alveolar-arterial PO2 gradient under 100% oxygen (AaPO2), contrast echocardiography, and radionuclide perfusion lung scanning. Contrast echocardiography in the supine position was the most sensitive test (93%). The sensitivity of self-reported dyspnea (59%), chest radiograph alone (70%), measurement of AaPO2 by the 100% oxygen method (62%), or radionuclide lung scanning (71%), was not suitable for efficient screening. A 100% sensitivity and negative predictive value could be obtained when combining anteroposterior chest radiograph and contrast echocardiography. Our data support a screening algorithm based on the combined use of contrast echocardiography and anteroposterior chest radiograph, followed by chest CT if either test is positive. An alternative is to screen directly by chest CT. However, this algorithm may obviate the need for chest CT in patients without PAVM, who represent a majority of patients with hereditary hemorrhagic telangiectasia.     

Pulmonary arteriovenous malformations and migraine: a new vision

Migraine is a common neurological disorder with a great impact on the quality of life and social activities. Pulmonary arteriovenous malformations (PAVMs) are mostly congenital, with a prevalence of 5-50% in patients with hereditary hemorrhagic telangiectasia (HHT). A high prevalence of PAVMs is found in patients with HHT and migraine. Embolization of PAVMs seems to decrease the prevalence of migraine. Different pathophysiological hypotheses have been proposed to explain the association between migraine and the different right-to-left shunts. This review article describes the association between a pulmonary right-to-left shunt and the occurrence of migraine.     

Contrast echocardiography grading predicts pulmonary arteriovenous malformations on CT

BACKGROUND: Untreated pulmonary arteriovenous malformations (PAVMs) can present with life-threatening complications. Agitated saline solution transthoracic contrast echocardiography (TTCE) has been recommended as the screening test of choice for PAVMs in hereditary hemorrhagic telangiectasia (HHT). A TTCE grading system has been proposed but not validated. The aim of this study was to determine the positive predictive value (PPV) of TTCE grades for the presence of PAVMs on CT. METHODS: A blinded retrospective review was conducted. All patients screened at the Toronto HHT Center (June 2002 to September 2004) with positive TTCE results were included. TTCE results were scored for delay (number of cardiac cycles) before appearance of microcavitations in the left atrium and graded for intensity of opacification. Grade 1 indicates minimal left ventricular opacification, grade 2 indicates moderate opacification, grade 3 indicates extensive opacification without outlining the endocardium, and grade 4 indicates extensive opacification with endocardial definition. Thoracic CT was performed in all patients, and results were scored as positive, negative, or indeterminate for PAVMs. RESULTS: Of 155 patients screened for PAVMs, 104 had positive TTCE results. Complete data were available for 90 patients (87%). Mean age was 45 years; 62% were female. Seventeen percent of patients screened and 27% of patients with positive TTCE results had CT detectable PAVMs. There was a significant association between TTCE grade and presence of PAVMs on CT (p < 0.0001). The PPV of grades 1, 2, 3, and 4 were 0.02 (95% confidence interval, 0.00 to 0.06), 0.25 (95% confidence interval, 0.06 to 0.44), 0.56 (95% confidence interval, 0.23 to 0.88), and 1.0 (95% confidence interval, 1.0 to 1.0), respectively. CONCLUSIONS: Increased shunt grade predicts increased probability of PAVMs and may be used to guide decisions in the screening algorithm for PAVMs.     

Pulmonary arteriovenous fistula discovered after percutaneous patent foramen ovale closure in a 27-year-old woman

We report the case of a 27-year-old woman with history of a transient ischemic attack who was diagnosed with a large patent foramen ovale (PFO). After percutaneous PFO closure, it was discovered that the patient had a pulmonary arteriovenous malformation (PAVM) and a diagnosis of hereditary hemorrhagic telangiectasia was made. The PAVM was later coil embolized. This case illustrates the importance of evaluating PFO closure patients for other causes of right-to-left shunting.     

Hereditary hemorrhagic teleangiectasia (Rendu-Osler-Weber disease)

Rendu-Osler-Weber disease, or hereditary hemorrhagic telangiectasia (HHT), is an autosomal dominant disorder with incomplete penetrance, characterized by vascular anomalies which may virtually develop in many organs. The prevalence varies and may range from 1/3,500 to 1/5,000 in specific regions. Two chromosal sites have been at least identified: in HHT1, mutations at chromosome 9 alter the protein endoglin and in HHT2, mutations at chromosome 12 alter the protein activine or ALK-1. Clinical manifestations include recurrent epistaxis, mucocutaneous telangiectases that bleed easily, and larger arteriovenous malformations in parenchymatous organs. Epistaxis is the first symptom, occurring in the vast majority of affected persons. The lung is the most common site for arteriovenous malformations. Brain abscess, transient ischemic attack and ischemic stroke occur exclusively in patients with pulmonary arteriovenous malformations and right-to-left shunt, which facilitates the passage of emboli into the cerebral circulation. Transcatheter embolotherapy with detachable balloons or stainless-steel coils has been used in order to occlude such malformations and to prevent such complications. At present a genetic diagnosis is possible in only a few families. The clinical diagnosis is based on 4 criteria: family history, epistaxis, mucocutaneous telangiectases and arteriovenous malformations. The diagnosis will be definite if 3 criteria are present, suspected if 2 criteria are present, unlikely if fewer than 2 criteria are present. In conclusion, the authors examine clinical features of 28 HHT patients observed in the HHT University Centre of Bari from September 2000 to May 2001.     

Rendu-Osler-Weber syndrome. Pulmonary arteriovenous fistulas. A report of three cases

Hereditary hemorrhagic telangiectasia (HHT), or Rendu-Osler-Weber syndrome, is a rare disorder that is closely linked to the development of pulmonary arteriovenous malformations (PAVM). Diagnosis can be based on clinical signs such as upper respiratory tract changes or recurrent hemorrhagic events. Nevertheless, pulmonary involvement, a prognostic factor, may remain undetected. In the three HTT cases with PAVM we report, the following diagnostic information was obtained non-invasively: shunt fraction measurements (breathing 100% oxygen), echocardiographic contrast studies, and three-dimensional helical computed tomographs. Arteriography demonstrated a single PAVM in one case and the patient underwent successful coil embolization, with clinical and functional improvement.     

Transcatheter closure of pulmonary arteriovenous malformations with amplatzer devices.

OBJECTIVE: To review the authors' experience with transcatheter closure of pulmonary arteriovenous malformations (PAVMs) using amplatzer duct occluder (ADO) devices and vascular plugs (AGA Medical, Golden Valley, MN) and present a novel technique for delivery sheath placement and device delivery. BACKGROUND: PAVMs can cause cyanosis, fatigue, polycythemia, and thromboembolic phenomena. Transcatheter closure using coils, detachable balloons, and various devices has replaced surgery as the preferred therapy. METHODS: Between January 2001 and December 2004, five patients (2M, 3F) of median age 33 years (14-49) were referred for transcatheter closure of multiple PAVMs. All patients were diagnosed previously with hereditary hemorrhagic telangectasia. The procedures were performed with sedation using a percutaneous transcatheter technique via the femoral vein under fluoroscopic guidance. RESULTS: A total of 14 PAVMs (11 ADO and 3 plugs) were closed in five patients. Three patients required two procedures after developing additional PAVMs. All attempts at PAVM closure were successful. Oxygen saturation increased from 88.4 +/- 6.1 to 96.4 +/- 0.5 (P < 0.05). No complications, including air or thromboembolism, hemoptysis, or chest pain, occurred. At median follow-up of 3.4 years (1.4-3.6), all patients are alive and have suffered no embolic phenomena or infection. CONCLUSION: Amplatzer patent ductus arteriosus occluders and vascular plugs are safe and effective in the closure of PAVMs in the acute setting and at intermediate follow-up. Placement of a long delivery sheath can be facilitated by the methods outlined. Though promising, further clinical evaluation of these devices is required. Their apparent advantages must be compared to other techniques and devices for transcatheter PAVM closure.     

Effect of percutaneous transcatheter embolization on pulmonary function, right-to-left shunt, and arterial oxygenation in patients with pulmonary arteriovenous malformations

The effects of percutaneous transcatheter embolization on pulmonary function and exercise capacity were assessed in 15 patients with pulmonary arteriovenous malformations (PAVM). Vital capacity (VC), FEV1, DLCO, SaO2, exercise performance, and right-to-left shunt (100% oxygen method) were measured before and 2 to 6 months after treatment. Surgical correction had been attempted in 9 patients prior to referral, and 11 had associated hereditary hemorrhagic telangiectasia (HHT). Lung function tests before intervention showed normal VC and FEV1/VC ratios, reduced DLCO (mean 71% predicted, range 36 to 123%), a resting supine SaO2 of 86% (range 67 to 95%) and mean shunt fraction of 33% (range 15 to 47%). Despite further marked falls in SaO2 on exertion, exercise capacity was well preserved. Following steel coil embolization of all PAVM with a feed vessel internal diameter greater than 3 mm (one to four sessions per patient), mean shunt fraction improved from 33 to 19% and resting SaO2 from 86 to 92% with no change in VC. A consistent improvement in diffusing capacity was seen only in patients with coexisting HHT. Exercise capacity increased in the majority (unchanged in 6), and SaO2 during maximal exercise improved in all except one patient. There were no long-term complications following embolization. These findings indicate that embolization of all macroscopic PAVM, undertaken primarily to reduce the risk of paradoxical embolization, is safe and results in substantial improvements in resting and exercise SaO2 without evidence of loss of normal lung. The right-to-left shunts remaining following embolization may reflect the presence of numerous microscopic PAVM in these patients.