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Letter to the editor: “Pulsatile pulmonary artery pressure: are fluid-filled catheters accurate in pulmonary hypertension?”

2013; American Physical Society; Volume: 305; Issue: 11 Linguagem: Inglês

10.1152/ajpheart.00713.2013

1522-1539

D. S. Chemla, Vincent Castelain, Philippe Hervé,

Cardiovascular Issues in Pregnancy

Letters to the EditorLetter to the editor: “Pulsatile pulmonary artery pressure: are fluid-filled catheters accurate in pulmonary hypertension?”Denis Chemla, Vincent Castelain, and Philippe HerveDenis ChemlaPhysiology Department, University Paris Sud, Faculté de Médecine-EA4533-APHP, Le Kremlin Bicêtre, France; , Vincent CastelainHôpitaux universitaires de Strasbourg, Service de réanimation médicale, Strasbourg, France; and , and Philippe HerveCentre Chirurgical Marie Lannelongue, Le Plessis-Robinson, FrancePublished Online:01 Dec 2013https://doi.org/10.1152/ajpheart.00713.2013MoreSectionsPDF (51 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInEmailWeChat to the editor: We have read with interest the article “Decreased time constant of the pulmonary circulation in chronic thromboembolic pulmonary hypertension,” by MacKenzie Ross et al. (6). Using fluid-filled catheters, the authors have documented that the pulmonary arterial time constant is decreased in patients with proximal chronic thromboembolic pulmonary hypertension (CTEPH) compared with idiopathic pulmonary arterial hypertension. The empirical relationship between mean pulmonary artery pressure (mPAP) and systolic pressure (sPAP) (2, 3, 9) was also found to be altered by the presence of proximal thromboembolic obstructions (6). As a result, the equations to predict mPAP from sPAP used in clinical practice when sPAP is estimated from the maximum velocity of tricuspid regurgitant jet at echocardiography have to be adapted in proximal CTEPH with a lower mPAP recalculated from any sPAP estimate (6).The empirical equation first proposed by our group was as follows: mPAP = 0.61 sPAP + 2 mmHg (2). The strong linear relationship between sPAP and mPAP has been confirmed by Syyed et al. (9). Our empirical equation has been further confirmed in a total of 166 individuals studied with micromanometer-tipped catheter, of whom 57% had pulmonary hypertension (PH) caused by many different conditions (3). A recent fluid-filled catheter pressure study performed in 307 patients, mainly with left heart diseases, has documented an empirical equation strictly identical to ours, namely mPAP = 0.61 sPAP + 1.95 mmHg (8). Very recently, a retrospective fluid-filled catheter pressure study of 463 congestive heart failure patients with reduced ejection fraction and no PH, venous PH, or mixed venous and superimposed arterial PH has also reported an empirical equation remarkably similar to ours, namely mPAP = 0.615 sPAP + 3 mmHg (7). The authors of the current study (6) indicate that their results in idiopathic pulmonary arterial hypertension are in keeping with previous empirical equations including ours as they “generated a remarkably similar relationship between mean and systolic pressures as those observed using high-fidelity catheters, suggesting that this has little impact on our measurements.” Conversely, their results in CTEPH (6) clearly challenge previous empirical equations (2, 3, 7–9).Our esteemed colleagues are experts in the field of pulmonary circulation. However, before accepting their conclusion, we have checked whether or not their new modified equation works in the subgroup of CTEPH patients whose individual pressure values have been previously published by two independent research groups using micromanometer-tipped catheters (2, 9). If one applies the author's equation to predict mPAP in our seven CTEPH (proximal) (2), this leads to a −7 ± 4 mmHg mPAP bias (mean ± SD). In the seven CTEPH patients studied by Syyed et al. (9), the new equation leads to a −8 ± 4 and −6 ± 3 mmHg mPAP bias, assuming proximal or distal obstruction, respectively. It must be acknowledged that these negative results were derived from a relatively small number of CTEPH patients (n = 14), but the fact that the authors (6) have studied a much larger number of patients in no way guarantees the accuracy of their measurement. Given such marked discrepancies, favoring the results obtained with fluid-filled catheters (6) over those obtained with micromanometer-tipped catheter (2, 9) is counterintuitive.One may wonder why standard catheters reliably picture the empirical relationship existing between mPAP and sPAP in numerous forms of PH (2, 3, 6–9) but not in CTEPH. Our hypothesis is that wave reflection phenomena are tremendously increased in CTEPH (1, 4), as acknowledged by the authors themselves (6), and that this is responsible for pulsatile pressure characteristics that cannot be reliably captured by standard catheters given their frequency response (4, 5). It is admitted that this may affect systolic pressure to a greater extent than the time-averaged mean pressure (4, 5). The resulting inaccuracies in the estimation of sPAP may have biased the mPAP versus sPAP relationship in CTEPH patients studied with fluid-filled catheters. This could explain the discrepancies with micromanometer-tipped catheter results discussed above. Consistently, if one compares the various empirical equations (2, 6), such discrepancies appear more marked in the patients with the highest sPAP values, i.e., in the patients who are likely to experience the most enhanced wave reflection phenomena. Thus, while fluid-filled catheters furnish invaluable information for current clinical care studies in CTEPH, one must be cautious to draw any firm conclusion on pulsatile pressure pathophysiology, even when strict technical requirements are met (5). As previously stressed, however, we fully agree that care is needed when applying our empirical equation to some subsets of patients, especially in cases where there is a ventricularization of the PAP curve due to proximal obstacle (e.g., pulmonary embolism) (2, 3).Thus we cannot exclude the possibility that a slightly different empirical equation relating mPAP and sPAP may apply in CTEPH, especially proximal CTEPH.In conclusion, when applied to a database of 14 CTEPH patients whose individual pressure values have been previously documented by two independent research groups using high-fidelity recordings (2, 9), the new modified empirical equation proposed in CTEPH (6) does not work (i.e., mPAP is markedly underestimated). Here we respectfully suggest the possibility of a technical limitation of fluid-filled catheters given marked pressure wave reflections in CTEPH. The ability of the modified equation to accurately quantify the physiological link between the mean and pulsatile components of pulmonary artery load in CTEPH thus remains questionable. Before further studies are performed in a large CTEPH population to precisely document the mPAP-sPAP relationship with micromanometer-tipped catheter, caution is needed and the use of the modified equation (6) cannot be recommended in routine.DISCLOSURESNo conflicts of interest, financial or otherwise, are declared by the author(s).AUTHOR CONTRIBUTIONSD.C., V.C., and P.H. drafted manuscript; D.C., V.C., and P.H. edited and revised manuscript; D.C., V.C., and P.H. approved final version of manuscript.REFERENCES1. Castelain V , Hervé P , Lecarpentier Y , Duroux P , Simonneau G, Chemla D. Pulmonary artery pulse pressure and wave reflection in chronic pulmonary thromboembolism and primary pulmonary hypertension. J Am Coll Cardiol 37: 1085–1092, 2001.Crossref | PubMed | ISI | Google Scholar2. Chemla D, Castelain V, Humbert M, Hébert JL, Simonneau G, Lecarpentier Y, Herve P. New formula for predicting mean pulmonary artery pressure using systolic pulmonary artery pressure. Chest 126: 1313–1317, 2004.Crossref | PubMed | ISI | Google Scholar3. Chemla D, Castelain V, Provencher S, Humbert M, Simonneau G, Herve P. Evaluation of various empirical formulas for estimating mean pulmonary artery pressure by using systolic pulmonary artery pressure in adults. Chest 135: 760–768, 2009.Crossref | PubMed | ISI | Google Scholar4. Chemla D , Castelain V , Simonneau G, Lecarpentier Y, Hervé P. Pulse wave reflection in pulmonary hypertension. J Am Coll Cardiol 39: 743–744, 2002.Crossref | PubMed | ISI | Google Scholar5. Grossman W. Pressure measurement. In: Grossman's Cardiac Catheterization, Angiography, and Intervention (7th ed.), edited by , Baim D. S. Philadelphia: Lippincott Williams & Wilkins, 2006, p. 137–147.Google Scholar6. MacKenzie Ross RV, Toshner MR, Soon E, Naeije R, Pepke-Zaba J. Decreased time constant of the pulmonary circulation in chronic thromboembolic pulmonary hypertension. Am J Physiol Heart Circ Physiol 305: H259–H264, 2013.Link | ISI | Google Scholar7. Miller WL, Grill DE, Borlaug BA. Clinical features, hemodynamics, and outcomes of pulmonary hypertension due to chronic heart failure with reduced ejection fraction. JACC Heart Fail 1: 290–299, 2013.Crossref | PubMed | ISI | Google Scholar8. Steckelberg RC, Tseng AS, Nishimura R, Ommen S, Sorajja P. Derivation of mean pulmonary artery pressure from noninvasive parameters. J Am Soc Echocardiogr 26: 464–468, 2013.Crossref | PubMed | ISI | Google Scholar9. Syyed R, Reeves JT, Welsh D, Raeside D, Johson MK, Peacock AJ. The relationship between the components of pulmonary artery pressure remains constant under all conditions in both health and disease. Chest 133: 633–639, 2008.Crossref | PubMed | ISI | Google ScholarAUTHOR NOTESAddress for reprint requests and other correspondence: Correspondence: D. Chemla, Service des Explorations Fonctionnelles—Broca 7, Hôpital de Bicêtre, 78 rue du Général Leclerc, 94 275 Le Kremlin Bicêtre, France (e-mail: denis.[email protected]aphp.fr). Download PDF Previous Back to Top Next FiguresReferencesRelatedInformationRelated articlesReply to “Letter to the editor: ‘Pulsatile pulmonary artery pressure: are fluid-filled catheters accurate in pulmonary hypertension?'” 01 Dec 2013American Journal of Physiology-Heart and Circulatory PhysiologyCited BySystolic and Mean Pulmonary Artery PressuresChest, Vol. 147, No. 4The resistance-compliance product of the pulmonary circulation varies in health and pulmonary vascular disease22 April 2015 | Physiological Reports, Vol. 3, No. 4Reply to “Letter to the editor: ‘Pulsatile pulmonary artery pressure: are fluid-filled catheters accurate in pulmonary hypertension?'”Robert V. MacKenzie Ross, Mark R. Toshner, Elaine Soon, Robert Naeije, and Joanna Pepke-Zaba1 December 2013 | American Journal of Physiology-Heart and Circulatory Physiology, Vol. 305, No. 11 More from this issue > Volume 305Issue 11December 2013Pages H1680-H1681 Copyright & PermissionsCopyright © 2013 the American Physiological Societyhttps://doi.org/10.1152/ajpheart.00713.2013PubMed24293425History Published online 1 December 2013 Published in print 1 December 2013 Metrics