Pulmonary Arteriovenous Malformations In Patients Research Articles

Angiographic tool to detect pulmonary arteriovenous malformations in single ventricle physiology.

Individuals with single ventricle physiology who are palliated with superior cavopulmonary anastomosis (Glenn surgery) may develop pulmonary arteriovenous malformations. The traditional tools for pulmonary arteriovenous malformation diagnosis are often of limited diagnostic utility in this patient population. We sought to measure the pulmonary capillary transit time to determine its value as a tool to identify pulmonary arteriovenous malformations in patients with single ventricle physiology. We defined the angiographic pulmonary capillary transit time as the number of cardiac cycles required for transit of contrast from the distal pulmonary arteries to the pulmonary veins. Patients were retrospectively recruited from a single quaternary North American paediatric centre, and angiographic and clinical data were reviewed. Pulmonary capillary transit time was calculated in 20 control patients and compared to 20 single ventricle patients at the pre-Glenn, Glenn, and Fontan surgical stages (which were compared with a linear-mixed model). Correlation (Pearson) between pulmonary capillary transit time and haemodynamic and injection parameters was assessed using angiograms from 84 Glenn patients. Five independent observers calculated pulmonary capillary transit time to measure reproducibility (intraclass correlation coefficient). Mean pulmonary capillary transit time was 3.3 cardiac cycles in the control population, and 3.5, 2.4, and 3.5 in the pre-Glenn, Glenn, and Fontan stages, respectively. Pulmonary capillary transit time in the Glenn population did not correlate with injection conditions. Intraclass correlation coefficient was 0.87. Pulmonary angiography can be used to calculate the pulmonary capillary transit time, which is reproducible between observers. Pulmonary capillary transit time accelerates in the Glenn stage, correlating with absence of direct hepatopulmonary venous flow.

Pulmonary arteriovenous malformations in patients with previous brain abscess: a cross-sectional population-based study.

Pulmonary arteriovenous malformations (PAVMs) may cause recurrent brain abscess. The primary aim was to determine the prevalence of PAVM amongst survivors of brain abscess. The proportion with cardiac right-to-left shunts was also assessed post hoc. This was a cross-sectional population-based study of adult (≥18 years) survivors of cryptogenic bacterial brain abscess in Denmark from 2007 through 2016. Patients were invited for bubble-echocardiography to detect vascular right-to-left shunting and, if abnormal, subsequent computed tomography thorax for diagnosis of PAVM. Data are presented as n/N (%) or median with interquartile range (IQR). Study participation was accepted by 47/157 (30%) eligible patients amongst whom two did not appear for scheduled bubble-echocardiography. The median age of participants was 54 years (IQR 45-62) and 19/57 (33%) were females compared with 59 years (IQR 48-68, p = 0.05) and 41/85 females (48%, p = 0.22) in non-participants. Bubble-echocardiography was suggestive of shunt in 10/45 (22%) participants and PAVM was subsequently confirmed by computed tomography in one patient with grade 1 shunting. The corresponding prevalence of PAVM was 2% (95% confidence interval 0.06-11.8) amongst all examined participants. Another 9/45 (20%) were diagnosed with patent in persistent foramen ovale (n = 8) or atrial septum defect (n = 1), which is comparable with the overall prevalence of 25% amongst adults in the Danish background population. Undiagnosed PAVM amongst adult survivors of cryptogenic bacterial brain abscess is rare but may be considered in select patients. The prevalence of cardiac right-to-left shunts amongst brain abscess patients corresponds to the prevalence in the general population.

UNTREATED PULMONARY ARTERIOVENOUS MALFORMATIONS IN A CARDIORESPIRATORY STORM

UNTREATED PULMONARY ARTERIOVENOUS MALFORMATIONS IN A CARDIORESPIRATORY STORM

SVEGFR1 Is Enriched in Hepatic Vein Blood-Evidence for a Provisional Hepatic Factor Candidate?

Background: Pulmonary arteriovenous malformations (PAVMs) are common sequelae of palliated univentricular congenital heart disease, yet their pathogenesis remain poorly defined. In this preliminary study, we used paired patient blood samples to identify potential hepatic factor candidates enriched in hepatic vein blood.Methods: Paired venous blood samples were collected from the hepatic vein (HV) and superior vena cava (SVC) from children 0 to 10 years with univentricular and biventricular congenital heart disease (n = 40). We used three independent protein analyses to identify proteomic differences between HV and SVC blood. Subsequently, we investigated the relevance of our quantified protein differences with human lung microvascular endothelial assays.Results: Two independent protein arrays (semi-quantitative immunoblot and quantitative array) identified that soluble vascular endothelial growth factor receptor 1 (sVEGFR1) is significantly elevated in HV serum compared to SVC serum. Using ELISA, we confirmed the previous findings that sVEGFR1 is enriched in HV serum (n = 24, p < 0.0001). Finally, we studied the quantified HV and SVC serum levels of sVEGFR1 in vitro. HV levels of sVEGFR1 decreased tip cell selection (p = 0.0482) and tube formation (fewer tubes [p = 0.0246], shorter tube length [p = 0.0300]) in vitro compared to SVC levels of sVEGFR1.Conclusions: Based on a small heterogenous cohort, sVEGFR1 is elevated in HV serum compared to paired SVC samples, and the mean sVEGFR1 concentrations in these two systemic veins cause pulmonary endothelial phenotypic differences in vitro. Further research is needed to determine whether sVEGFR1 has a direct role in pulmonary microvascular remodeling and PAVMs in patients with palliated univentricular congenital heart disease.

Safety of Catheter Embolization of Pulmonary Arteriovenous Malformations-Evaluation of Possible Cerebrovascular Embolism after Catheter Embolization of Pulmonary Arteriovenous Malformations in Patients with Hereditary Hemorrhagic Telangiectasia/Osler Disease by Pre- and Post-Interventional DWI.

Background. This paper aimed to prospectively evaluate the safety of embolization therapy of pulmonary arteriovenous malformations (PAVMs) for the detection of cerebral infarctions by pre- and post-interventional MRI. Method One hundred and five patients (male/female = 44/61; mean age 48.6+/−15.8; range 5–86) with pre-diagnosed PAVMs on contrast-enhanced MRA underwent embolization therapy. The number of PAVMs treated in each patient ranged from 1–8 PAVMs. Depending on the size and localization of the feeding arteries, either Nester-Coils or Amplatzer vascular plugs were used for embolization therapy. cMRI was performed immediately before, and at the 4 h and 3-month post-embolization therapy. Detection of peri-interventional cerebral emboli was performed via T2w and DWI sequences using three different b-values, with calculation of ADC maps. Results Embolization did not show any post-/peri-interventional, newly developed ischemic lesions in the brain. Only one patient who underwent re-embolization and was previously treated with tungsten coils that corroded over time showed newly developed, small, diffuse emboli in the post-interventional DWI sequence. This patient already had several episodes of brain emboli before re-treatment due to the corroded coils, and during treatment, when passing the corroded coils, experienced additional small, clinically inconspicuous brain emboli. However, this complication was anticipated but accepted, since the vessel had to be occluded distally. Conclusion Catheter-based embolization of PAVMs is a safe method for treatment and does not result in clinically inconspicuous cerebral ischemia, which was not demonstrated previously.

Pulmonary arteriovenous malformations in children after the Kawashima procedure: Risk factors and midterm outcome.

Background:Pulmonary arteriovenous malformations (PAVMs) are the major cause of progressive cyanosis in patients palliated with bidirectional cavopulmonary connection (BCPC). The aim of our study is to analyze the occurrence of PAVMs in patients after Kawashima procedure, to study the effect of total cavopulmonary connection (TCPC) on PAVMs, to evaluate the effect of axillary arteriovenous fistula (AAVF) creation on PAVMs, and to study the risk factors for PAVMs.Methods:In this retrospective cohort study, all patients with left isomerism and azygous continuation of an interrupted inferior vena cava who underwent Kawashima procedure from July 2001 to December 2017 were included.Results:Twenty.six patients after Kawashima procedure were included in our study. PAVMs were diagnosed in 12 patients (46%). Five of these 12 patients underwent TCPC with complete resolution of hypoxemia. Three patients underwent AAVF creation, 2 had complete resolution, while 1 had partial resolution of hypoxemia. Fourteen patients (54%) did not develop PAVMs. Nakata index below 267 mm2/m2and McGoon ratio below 1.9 predicted the development of PAVMs with high sensitivity and specificity.Conclusions:PAVMs represent a serious complication in patients who undergo Kawashima procedure. Small size of pulmonary arteries is an important risk factor for the development of PAVMs. Resolution of hypoxemia after TCPC completion supports the hepatic factor hypothesis. Early TCPC completion in these patients may help to avoid the development of PAVMs by restoring the hepatic factor. Resolution of hypoxemia after AAVF creation may support the lack of pulsatile flow hypothesis.

RECURRENT ISCHEMIC STROKE SECONDARY TO PULMONARY ARTERIOVENOUS MALFORMATIONS

SESSION TITLE: Tuesday Medical Student/Resident Case Report Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: 10/22/2019 01:00 PM - 02:00 PM INTRODUCTION: Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant vascular disorder that has a variety of clinical manifestations and can affect many organ systems. Prevalence rates of HHT are estimated to be between 1:5000 and 1:8000. Knowledge of the risk of developing pulmonary arteriovenous malformations associated with HHT is essential to prevent potentially catastrophic complications, including stroke. CASE PRESENTATION: A 42 year-old female, non-smoker with hereditary hemorrhagic telangiectasia, headaches, epistaxis, and multiple strokes presented with an hour of dizziness, slurred speech, and right sided weakness. Her symptoms completely resolved within three hours of arrival. Family history was significant for three family members with HHT. On physical exam she had dried blood in her nares and multiple blanching telangiectasias on her lips and arms. Her lungs were clear without adventitious sounds on room air and she had no neurologic deficits. CT scan of the head did not demonstrate acute hemorrhage. She had a normal ejection fraction with a positive bubble study on contrast enhanced echocardiogram. She coughed up a quarter-sized bright red blood clot after arrival. She denied a history of massive hemoptysis. CT chest demonstrated a two centimeter right pulmonary arteriovenous malformation (AVM) in the right lower lobe, an eight millimeter left lower lobe AVM, and multiple smaller AVMs throughout both lungs. She underwent coil embolization of the largest AVMs by interventional radiology, and post-embolization angiogram showed no further flow in the arterial branches feeding the AVMs. Within two months, her headaches had improved and she was no longer developing transient slurred speech or unilateral weakness. DISCUSSION: Pulmonary AVMs in patients with HHT are under recognized and undertreated as patients are often asymptomatic, and patients with HHT can have catastrophic strokes before their AVMs are identified. The incidence of pulmonary AVMs in patients with HHT exceeds 50%. In this case, the patient had two strokes secondary to paradoxical emboli before her pulmonary AVMs were identified. The British Thoracic Society recommends that all patients over age 16 with known or suspected HHT should be offered screening for pulmonary AVMs, and that patients with pulmonary AVMs should be considered for referral for embolization. CONCLUSIONS: Screening for asymptomatic pulmonary AVMs and subsequent embolization of pulmonary AVMs in hereditary hemorrhagic telangiectasia is critical to decreasing the morbidity and mortality associated with cerebral abscess and cerebral ischemia from paradoxical emboli, hemoptysis, and hemothorax associated with pulmonary AVMs secondary to HHT. Reference #1: Dupuis-Girod S, Cottin V, Shovlin C, L. The Lung in Hereditary Hemorrhagic Telangiectasia. Respiration. 2017; 94:315-330. Reference #2: Shovlin CL, Condliffe R, Donaldson JW on behalf of the British Thoracic Society, et al. British Thoracic Society Clinical Statement on Pulmonary Arteriovenous Malformations. Thorax. 2017; 72:1154-1163. DISCLOSURES: No relevant relationships by Daniel Hershberger, source=Web Response No relevant relationships by Maureen McElligott, source=Web Response

Smoking Significantly Impacts Persistence Rates in Embolized Pulmonary Arteriovenous Malformations in Patients with Hereditary Hemorrhagic Telangiectasia.

BackgroundEmbolization is the standard of care for treatment of pulmonary arteriovenous malformations (PAVMs). Persistence of PAVMs after embolization occurs for undefined reasons but may include inflammation related to smoking in dysregulated angiogenesis.PurposeTo determine whether patients with hereditary hemorrhagic telangiectasia (HHT) who smoke tobacco are more prone to PAVM persistence after embolization.Materials and MethodsPatients with HHT treated for PAVMs between January 2000 and August 2017 were retrospectively identified. Only PAVMs with no previous treatment and patients with both clinical and imaging follow-up were included. Age, sex, PAVM characteristics (size, complexity, and location), embolization material used, microcatheter type, smoking history, active tobacco use, and other risk factors for arterial disease were analyzed by using a multivariate Cox proportional hazards model to determine risk factors for persistence.ResultsFive-year persistence-free survival rates in nonsmokers, smokers of 1–20 pack-years, and smokers of more than 20 pack-years were 12.2%, 21.9%, and 37.4% respectively. Smokers with more than 20 pack-years relative to nonsmokers had greater risk of persistence after adjusting for arterial feeder size (hazard ratio, 3.8; 95% confidence interval [CI]: 1.5, 10.0; P = .007). Patients who reported active tobacco use at the time of PAVM embolization had a 5-year cumulative incidence of persistence of 26.3% compared with 13.5% in inactive smokers. After adjusting for arterial feeder size, the risk of persistence was greater in tobacco users versus inactive smokers at the time of treatment (hazard ratio, 2.4; 95% CI: 1.2, 4.7; P = .01).ConclusionSmoking is associated with pulmonary arteriovenous malformation persistence after embolization in patients with hereditary hemorrhagic telangiectasia. Online supplemental material is available for this article. See also the editorial by Trerotola and Pyeritz in this issue.

Lack of Growth of Small (≤2 mm Feeding Artery) Untreated Pulmonary Arteriovenous Malformations in Patients with Hereditary Hemorrhagic Telangiectasia

PurposeTo assess pulmonary arteriovenous malformation (PAVM) growth among patients with untreated PAVMs using imaging from long-term follow-up per hereditary hemorrhagic telangiectasia international guidelines. Materials and MethodsAnalysis included 88 untreated PAVMs from 21 patients (6 male;15 female; mean age at presentation 47 y; range, 12–68 y). Two CT studies with the longest interval between were evaluated (mean 8.4 y; median 8.8 y; range, 3.1–14.1 y). Measurement of feeding artery diameter and anteroposterior (AP) and mediolateral (ML) sac dimensions for each PAVM was performed separately by 2 radiologists blinded to patient and CT order. Statistical analysis was performed to determine change in size between earliest and follow-up imaging. ResultsMean feeding artery diameter, AP sac dimension, and ML sac dimension were 1.4 mm (range, 0.8–3.7 mm), 4.3 mm (range, 2.1–11.1 mm), and 4.1 mm (range, 1.8–9.2 mm) on earliest imaging and 1.4 mm (range, 0.9–2.6 mm), 4.5 mm (range, 2.2–12.2 mm), and 4.3 mm (range, 2.0–9.6 mm) on follow-up. Model-based mean analysis showed no statistically significant change in dimension of any variable between earliest and follow-up imaging. Secondary analysis including age also found no statistically significant difference (feeding diameter, P = .09; AP sac dimension, P = .9; ML sac dimension, P = .1). Analysis including time between measurements found no significant relationship between change in variables and time (feeding artery diameter, P = .4; AP sac dimension, P = .3; ML sac dimension, P = .06). ConclusionsUntreated PAVMs grew slowly, if at all, in a near-decade span, and any demonstrated growth was minimal. These findings challenge the current recommendation of 3- to 5-year CT follow-up.

Is the Hepatic Factor a miRNA that Maintains the Integrity of Pulmonary Microvasculature by Inhibiting the Vascular Endothelial Growth Factor?

Background:The “hepatic factor,” a molecule or group of molecules present in the hepatic venous blood, essential for the prevention of the development of pulmonary arteriovenous malfor-mations (PAVMs) and right-to-left shunting has been a conceptual enigma in the understanding of many related conditions.Methods:Patients with various forms of liver diseases including acute hepatic failure, and others with normal hepatic function like hereditary hemorrhagic telangiectasia (HHT), inflammatory and parasitic disorders, cardiogenic hepatopulmonary syndrome (cHPS) and skin disorders like Dyskeratosis con-genita are all known to cause PAVMs. Over a period of the last two decades our understanding of the pathogenesis of PAVMs has changed, but the mechanisms are still not clearly understood. The pres-ence of PAVMs once considered a contraindication for liver transplantation is now a cure for PAVMs in patients with HPS.Results:In this article the molecular mechanisms and the underlying pathogenesis of PAVMs are dis-cussed and the role of microRNA (miRNA) in its pathogenesis is favorably argued. Identifying and preventing or treating the underlying mechanisms will significantly influence the management of a large group of patients who at present cannot be effectively treated with a very poor prognosis. Progressive polycythemia, desaturation, stroke, and infection are serious complications of PAVMs.Conclusion:The clinical data and current understanding leads to the possible role of miRNA, which inhibits Vascular Endothelial Growth Factor (VEGF) synthesis as a pathogenic mechanism for the development of PAVMs.

Ischaemic stroke in a 21-year-old with hereditary haemorrhagic telangiectasia

A 21-year-old man presented with an acute ischaemic stroke. He had a history of epistaxis and a family history of hereditary haemorrhagic telangiectasia. We gave thrombolysis after some deliberation, and...

Amplatzer Vascular Plugs Versus Coils for Embolization of Pulmonary Arteriovenous Malformations in Patients with Hereditary Hemorrhagic Telangiectasia.

Coil embolization of pulmonary arteriovenous malformations (PAVMs) has a high re-canalization/re-perfusion rate. Embolization with Amplatzer plugs has been previously described, but the long-term efficacy is not established. This study reports the experience of a referral medical center with the use of coils and Amplatzer plugs for treating PAVMs in patients with hereditary hemorrhagic telangiectasia. The study was approved by the Institutional Review Board with waiver of informed consent. The cohort included all patients who underwent PAVM embolization in 2004-2014 for whom follow-up imaging scans were available. The medical files were retrospectively reviewed for background data, embolization method (coils, Amplatzer plugs, both), and complications. Re-canalization of treated PAVMs was assessed from intrapulmonary angiograms (following percutaneous procedures) or computed tomography angiograms. Fisher's exact test and Pearson Chi-squared test or t test were used for statistical analysis, with significance at p<0.05. 16 patients met the study criteria. Imaging scans were available for 63 of the total 110 PAVMs treated in 41 procedures. Coils were used for embolization in 37 PAVMs, Amplatzer plugs in 21, and both in five. Median follow-up time was 7.7years (range 1.4-18.9). Re-canalization was detected in seven vessels, all treated with coils; there were no cases of re-canalization in plug-occluded vessels (p=0.0413). The use of Amplatzer plugs for the embolization of PAVMs in patients with hemorrhagic telangiectasia is associated with a significantly lower rate of re-canalization of feeding vessels than coils. Long-term prospective studies are required to confirm these findings.

Usefulness of Transcranial Doppler for Detecting Pulmonary Arteriovenous Malformations in Hereditary Hemorrhagic Telangiectasia

The aim of this study was to assess transcranial Doppler (TCD) as a screening test for pulmonary arteriovenous malformation (PAVM) in patients with hereditary hemorrhagic telangiectasia (HHT). This retrospective study included suspected patients with HHT who were screened for PAVM with a TCD and a chest computed tomography (CT) study. The results of TCD and CT were compared to evaluate the usefulness of TCD for detecting PAVM. A TCD Spencer grade ≥3 was defined as positive for a significant right-to-left shunt (RLS). The diameter of the pulmonary arteries feeding the PAVM was measured by calipers from the CT study. In 86 subjects from 74 families with HHT, the sensitivity of TCD for identifying a PAVM at rest was 98% and post-Valsalva was 100%. Specificity was 58% and 35%, respectively, presumably due to pulmonary shunts too small to recognize on CT. Of the patients with HHT who were referred for embolization therapy for their PAVMs, all 20 had TCD grade ≥3. In patients who were diagnosed with a PAVM by chest CT, patients with TCD grade ≥5 had a significantly larger sum of artery diameters feeding the PAVMs compared to those with grade ≤4 (5.0 ± 3.2 mm vs 2.6 ± 1.9 mm, p = 0.01). In conclusion, a TCD examination for evaluating RLS is sensitive for identifying PAVM in patients with HHT and is useful in quantitating the degree of RLS flow. The sensitivity of the TCD examination makes it a useful screening test without radiation in HHT subjects to determine which patients need to undergo CT evaluation to identify PAVMs.

Pulmonary arteriovenous malformation-etiology, clinical four case presentations and review of the literature.

Pulmonary arteriovenous malformation (PAVM) is a rare clinical condition with abnormal direct communication between the branches of pulmonary artery and vein. It may occur as an isolated anomaly or in association with hereditary hemorrhagic telangiectasia (HHT). Although these vascular pulmonary pathologies are quite uncommon, they are the important part of the differential diagnosis of common pulmonary problems such as hypoxemia and pulmonary nodules. The diagnosis of PAVM in patients remains a diagnostic challenge to the emergency physician. The most common clinical signs of PAVM are recurrent episodes of epistaxis and hemoptysis, so surgical resection is deemed the best curative option to avoid further episodes and recurrence of hemoptysis. Quite often the diagnosis is established after pathohistological examinations. We report a case of a female patient with a massive recurrent hemoptysis and without pathologic radiological findings which would suggest to PAVM and who was successfully treated with lobectomy.

Pulmonary vascular complications of hereditary haemorrhagic telangiectasia

The purpose of this study is to present the latest advances and recommendations in the diagnosis and treatment of pulmonary vascular complications associated with hereditary haemorrhagic telangiectasia (HHT): pulmonary arteriovenous malformations (PAVMs), pulmonary arterial hypertension (PAH), pulmonary hypertension associated with high output cardiac failure or liver vascular malformations, haemoptysis, haemothorax and thromboembolic disease. Transthoracic contrast echocardiography has been validated as a screening tool for PAVM in patients with suspected HHT. Advancements in genetic testing support its use in family members at risk as a cost-effective measure. Therapy with bevacizumab in patients with high output cardiac failure and severe liver AVMs showed promising results. PAH tends to be more aggressive in HHT type 2 patients. Patients suffering from this elusive disease should be referred to HHT specialized centres to ensure a standardized and timely approach to diagnosis and management.

Endoglin deficiency impairs stroke recovery.

Endoglin deficiency causes hereditary hemorrhagic telangiectasia-1 and impairs myocardial repair. Pulmonary arteriovenous malformations in patients with hereditary hemorrhagic telangiectasia-1 are associated with a high incidence of paradoxical embolism in the cerebral circulation and ischemic brain injury. We hypothesized that endoglin deficiency impairs stroke recovery. Eng heterozygous (Eng+/-) and wild-type mice underwent permanent distal middle cerebral artery occlusion (pMCAO). Pial collateral vessels were quantified before pMCAO. Infarct/atrophic volume, vascular density, and macrophages were quantified in various days after pMCAO, and behavioral function was assessed using corner and adhesive removal tests on days 3, 15, 30, and 60 after pMCAO. The association between ENG 207G>A polymorphism and brain arteriovenous malformation rupture and surgery outcome was analyzed using logistic regression analysis in 256 ruptured and 157 unruptured patients. After pMCAO, Eng+/- mice showed larger infarct/atrophic volumes at all time points (P<0.05) and showed worse behavior performance (P<0.05) at 15, 30, and 60 days when compared with wild-type mice. Eng+/- mice had fewer macrophages on day 3 (P=0.009) and more macrophages on day 60 (P=0.02) in the peri-infarct region. Although Eng+/- and wild-type mice had similar numbers of pial collateral vessels before pMCAO, Eng+/- mice had lower vascular density in the peri-infarct region (P=0.05) on day 60 after pMCAO. In humans, ENG 207A allele has been associated with worse outcomes after arteriovenous malformation rupture or surgery of patients with unruptured arteriovenous malformation. Endoglin deficiency impairs brain injury recovery. Reduced angiogenesis, impaired macrophage homing, and delayed inflammation resolution could be the underlying mechanism.

Pulmonary Arteriovenous Malformations

Pulmonary arteriovenous malformations (PAVMs) are abnormal vascular structures that most often connect a pulmonary artery to a pulmonary vein, bypassing the normal pulmonary capillary bed and resulting in an intrapulmonary right-to-left shunt. As a consequence, patients with PAVM can have hypoxemia and paradoxical embolization complications, including stroke and brain abscess. PAVMs may be single or multiple, unilateral or bilateral, and simple or complex. Most PAVMs are hereditary and occur in hereditary hemorrhagic telangiectasia, an autosomal dominant vascular disorder, and screening for PAVM is indicated in this subgroup. PAVMs may also be idiopathic, occur as a result of trauma and infection, or be secondary to hepatopulmonary syndrome and bidirectional cavopulmonary shunting. Diagnostic testing involves identifying an intrapulmonary shunt, with the most sensitive test being transthoracic contrast echocardiography. Chest CT scan is useful in characterizing PAVM in patients with positive intrapulmonary shunting. Transcatheter embolotherapy is the treatment of choice for PAVM. Lifelong follow-up is important because recanalization and collateralization may occur after embolization therapy. Surgical resection is rarely necessary and reserved for patients who are not candidates for embolization. Antibiotic prophylaxis for procedures with a risk of bacteremia (eg, dental procedures) is recommended in all patients with PAVM because of the risk of cerebral abscess.

Pulmonary arteriovenous fistulas in patients with hereditary hemorrhagic telangiectasia: role of MR angiography

The aim of this work is to establish the accuracy of pulmonary magnetic resonance angiography (MRA) compared to multidetector computed tomography (MDCT) and pulmonary angiography in the diagnostic evaluation of pulmonary arteriovenous malformations (PAVMs) in patients with hereditary hemorrhagic telangiectasia. Eight consecutive patients underwent MRA, MDCT and pulmonary angiography. All patients were carriers of PAVMs amenable to endovascular treatment. The parameters we have evaluated were the presence, the number of fistulas and the diameter of the feeding artery of the malformation. In all cases, the findings of the three tests were comparable. In only one case, MR images were considered qualitatively poorer than MDCT, although sufficient for the recognition of the lesion located in the hilum. The diameters of the arteries showed no statistically differences between MRA and CT. In conclusion, the MRA technique was found to be valid and reliable in the diagnosis of PAVMs in patients with HHT.

Silent threat? A retrospective study of screening practices for pulmonary arteriovenous malformations in patients with hereditary haemorrhagic telangiectasia.

Patients with hereditary haemorrhagic telangiectasia (HHT) are at risk of pulmonary arteriovenous malformations (PAVMs) that may be complicated by stroke and brain abscess. ENT surgeons are well placed to direct patients to screening, which was recommended for all HHT patients in recently published international guidelines. A retrospective study of patients with known HHT was performed based on responses to a telephone questionnaire. Epistaxis was assessed using a validated epistaxis severity scoring system. 123 patients responded, with ages ranging from 14-86 years (mean 57 years). 80% of patients experienced their first symptom of HHT by 30 years old. Epistaxis was assessed at time of questionnaire as mild (26 patients), moderate (52 patients) or severe (45 patients). 71 patients (57.7% of total) underwent screening for PAVMs. 30 patients (42.2% of screened individuals) reported PAVMs detected by screening. 18 patients received treatment and 12 patients were found to have PAVMs too small for treatment. The modal screening method was computed tomography (CT, 58 patients) and the majority of patients with treatable PAVMs received trans-catheter embolisation (15 patients). Only 9 patients reported being under long term follow up for PAVMs. Shortness of breath (70.0% vs 41.5%, p<0.05) and migraine (43.3% vs 24.4%, p<0.05) were more common amongst patients found to have PAVMs than those without PAVMs. There was no difference in age of onset of HHT symptoms or epistaxis severity between patients with PAVMs and those without. PAVMs are common in HHT patients and carry a risk of morbidity and mortality. Safe and effective treatment exists for PAVMs although a significant minority of patients has received no screening to date. Clinicians should refer all patients for screening regardless of symptoms.

Shunt reduction to pulmonary arteriovenous malformations using a modified covered stent

Pulmonary arteriovenous malformations in patients with congenital heart disease have been associated with interruption of hepatic venous return to the lungs. We report a novel technique to improve systemic saturation using a modified covered stent in a patient with unilateral left pulmonary arteriovenous malformations in the setting of a Fontan circulation.