CL Shovlin

ER Chilvers

MK Whyte

P Andrivet

P Gupta

R Cartin-Ceba

T Churton

VMM Vorselaars

W Li

PubMed

Merkus, Daphne

EUR Research Repository

EDITORIAL COMMENTPulmonary arteriovenous malformations:haemodynamics and shunt closureD. MerkusPublished online: 26 March 2014# The Author(s) 2014. This article is published with open access at Springerlink.comThe first description of pulmonary arteriovenousmalformations (PAVM) was made already in 1897 byChurton [1]. PAVM are abnormal vascular structures thatconnect the pulmonary arterial bed directly to the pulmonaryvenous bed, thereby bypassing the pulmonary capillaries andresulting in an intrapulmonary shunt which, depending onnumber and size of the PAVM, may result in arterialdesaturation and paradoxical systemic embolisation [2].Because the PAVM are thin-walled vascular structures, theyare prone to rupture, resulting in haemoptysis. A major stepforward in the treatment of PAVMwas the use of percutaneoustranscatheter embolisation, using femoral venous access [3].This procedure is safe and reduces the risk of paradoxicalthromboembolisation and haemoptysis. Moreover, by reduc-ing shunt flow, arterial oxygen saturation increases.Although percutaneous closure of PAVM has been per-formed for years, and a surprisingly small effect on pulmonaryhaemodynamics has been shown [4], the study by Vorselaarsand co-workers in the present issue of the Netherlands HeartJournal [5] is the first to investigate the immediate conse-quences of PAVM closure on systemic haemodynamics.Using Finapres technology, which derives changes in strokevolume and systemic pressure from the pressure wave form asmeasured on a finger, they describe an overall decrease instroke volume and cardiac output that corresponds in magni-tude with the overall decrease in shunt fraction. This decreasein stroke volume is similar to the decrease in stroke volume, asmeasured directly by right heart catheterisation, observed in acase study at 4 months follow-up after PAVM [6]. It wasspeculated that such a decrease in stroke volume helped toexplain the absence of an increase in pulmonary arterypressures [4], despite the fact that pulmonary vascular resis-tance should obviously increase as a consequence of theclosure of the low resistance PAVM.The mechanism behind the observed decrease in strokevolume is unclear. It could be speculated that shunt closureand the accompanying increase in pulmonary vascular resis-tance result in a slight increase in right ventricular afterload,which limits right ventricular output. It is, however, morelikely to assume that oxygen is regulated to fulfil the oxygendemand of peripheral tissues; shunt closure increases theoxygen content of arterial blood and hence for the sameoxygen delivery, in the presence of improved oxygenation,less flow is required. The latter explanation is in accordancewith the observation that the shunt fraction prior to embolisa-tion (14 %) is similar in magnitude to the decrease in cardiacoutput (10 %) [5].As pulmonary artery pressure increases during exercise, thedriving pressure for the shunt flow increases, resulting in anincreased shunt flow, which is accompanied by augmentedarterial desaturation during exercise [7–9]. However, exercisecapacity is surprisingly well-maintained in patients withPAVM, potentially due to the capability of the right heart todeal with volume overload. Indeed, although most patientsreport an increased exercise capacity and quality of life fol-lowing shunt closure, an objective increase in exercise capac-ity is not found in all patients [10]. It is possible that changesin pulmonary and systemic haemodynamics upon shunt clo-sure, which are relatively small under resting conditions, areexacerbated during exercise. Thus, while the study byVorselaars in the present issue of the Netherlands HeartJournal provides an important observation in resting patients[5], a comprehensive evaluation of shunt flow, pulmonary andsystemic haemodynamics and oxygen saturation during exer-cise prior to and following shunt closure would be of greatbenefit to enhance our understanding of the implications ofshunt closure on exercise capacity.D. Merkus (*)Department of Cardiology, Erasmus MC, PO Box 2040, 3000CA Rotterdam, the Netherlandse-mail: d.merkus@erasmusmc.nlNeth Heart J (2014) 22:326–327DOI 10.1007/s12471-014-0546-8Funding None.Conflict of interest None declared.Open Access This article is distributed under the terms of the CreativeCommons Attribution License which permits any use, distribution, andreproduction in any medium, provided the original author(s) and thesource are credited.References1. Churton T. Multiple aneurysm of pulmonary artery. Br Med J (ClinRes Ed). 1897;1:1223.2. Cartin-Ceba R, Swanson KL, Krowka MJ. Pulmonary arteriovenousmalformations. Chest. 2013;144(3):1033–44.3. Chilvers ER, Whyte MK, Jackson JE, et al. Effect of percutaneoustranscatheter embolization on pulmonary function, right-to-left shunt,and arterial oxygenation in patients with pulmonary arteriovenousmalformations. Am Rev Respir Dis. 1990;142(2):420–5.4. Shovlin CL, Tighe HC, Davies RJ, et al. Embolisation of pulmonaryarteriovenous malformations: no consistent effect on pulmonary ar-tery pressure. Eur Respir J. 2008;32(1):162–9.5. Vorselaars VMM, Velthuis S, Mager JJ, et al. Direct hemo-dynamic effects of pulmonary arteriovenous malformationembolism. Neth Heart J. 2014. doi:10.1007/s12471-014-0539-7.6. Andrivet P, Lofaso F, Carette MF, et al. Haemodynamics andgas exchange before and after coil embolization of pulmo-nary arteriovenous malformations. Eur Respir J. 1995;8(7):1228–30.7. Li W, Niu B, Henderson K, et al. Reproducibility of oxygen satura-tion monitoring during six-minute walk test and exercise stress test inpatients with pulmonary arteriovenous malformations associatedwith hereditary hemorrhagic telangiectasia. Pediatr Cardiol.2011;32(5):590–4.8. Whyte MK, Hughes JM, Jackson JE, et al. Cardiopulmonary re-sponse to exercise in patients with intrapulmonary vascular shunts.J Appl Physiol. 1993;75(1):321–8.9. Whyte MK, Peters AM, Hughes JM, et al. Quantification ofright to left shunt at rest and during exercise in patients withpulmonary arteriovenous malformations. Thorax. 1992;47(10):790–6.10. Gupta P, Mordin C, Curtis J, et al. Pulmonary arteriovenousmalformations: effect of embolization on right-to-left shunt, hypox-emia, and exercise tolerance in 66 patients. AJR Am J Roentgenol.2002;179(2):347–55.Neth Heart J (2014) 22:326–327 327

Pulmonary arteriovenous malformations: Haemodynamics and shunt closure

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