© 2014, Wiley Periodicals, Inc. DOI: 10.1111/echo.12518
Echocardiography
LETTER TO THE EDITOR
Echocardiographic and Lung Ultrasound Characteristics in Ambulatory Patients with Dyspnea or Prior Heart Failure Dear Editor, The article by Platz et al.1 investigates the association of sonographic B-lines, a stated marker of extra-vascular lung water, with cardiac structure and function. The study was performed in a relatively stable outpatient population undergoing transthoracic echocardiography and lung ultrasound imaging (LUS). The count of B-lines, which are “artifacts,” is the diagnostic target, which, in our experience, appears inappropriate.2 B-lines are visible and approximately measured in conditions different from pulmonary congestion, and notably in chronic obstructive pulmonary disease3and pulmonary fibrosis4,5: it is a challenge to “count” them, being not an actual “measurement.”6,7 However, the main concern is related to the methodology. The most relevant reference studies, quoted also by the authors, did not use phased array transducers,1 but linear or convex probes. This makes all the difference as the number of B-lines is greater when using such transducers, particularly at the lower frequencies.2 We perform yearly intraobserver/inter-observer variability assessments of several US measurements, and repeat them each year at the end of our institutional postgraduate course in Clinical Ultrasound. A convex multifrequency 2-8 mHz probe was used with a MyLab Twice-ElaXto Ultrasound equipment (Esaote-Biomedica, Genoa, Italy). In 2013, in a sample of 20 MDs, with >5 years US practice and expertise (10 operators) or with 6 months of training in clinical US (10 operators), we asked them to assess twice the same movie clips of LUS with B-lines in 5 different clinical conditions; a fair intra-observer internal consistency is observed and the standard deviation is around 33.0% of the averages for each condition, considering the reports of all observers. Nonetheless, ranges of the B-lines individual counts are exceedingly wide for identical cases of each condition: pulmonary edema (3–10), chronic obstructive pulmonary disease exacerbation (4–10), pulmonary fibrosis (3–11), pleural effusion in congestive heart failure (HF) (3–10), pulmonary cancer lymphangitis (4–10). Which is the range for any measurement that the observers reported in the 406
cases studied by Platz et al.?1 Overall, the straightforward use of B-lines as “quantitative” measurements of B-lines is questionable. But the greater weakness is in cardiological data presentation and interpretation. (1) the most relevant correlation (not association as stated by the authors) is between B-lines count and LV mass index (g/m2): does it mean that we are dealing with a relationship of B-lines with left ventricular hypertrophy? (2) information on measures of left ventricular relaxation are available1: comments on the missing relationship of “lung congestion measures” with mechanisms involving left ventricular compliance should be interesting; (3) authors previously reported that “each additional B-line was associated with an increase in pulmonary artery systolic pressure of 1 mmHg”10 even if in the current noninvasive study relationship is weaker than with invasively measured cardiac pressures1: we could reasonably envisage effects deriving from inter-observer variability. It is difficult to agree with the authors’ overconfident conclusion: “sonographic B-lines in patients with HF should be thought of on a more continuous spectrum, similar to biomarkers, rather than a binary test to rule in (or out) acute pulmonary edema.” We, differently, prefer to rely on objective imaging achieved by lung ultrasound, such as pleural effusion, and on echocardiographic quantitative, objective, and reproducible measures, more than on nonspecific artifacts, as B-lines are.8,9 Guglielmo M. Trovato, M.D.,* Daniela Catalano, M.D.,* and Marco Sperandeo, M.D.† *Department of Medical and Pediatric Sciences, University of Catania, Catania, Italy †Department of Internal Medicine, IRCCS Casa Sollievo della Sofferenza Hospital, San Giovanni Rotondo, Italy References 1. Platz E, Hempel D, Pivetta E, et al: Echocardiographic and lung ultrasound characteristics in ambulatory patients with dyspnea or prior heart failure. Echocardiography 2014;31:133–139.
Letter to the Editor
2. Sperandeo M, Varriale A, Sperandeo G, et al: Assessment of ultrasound acoustic artifacts in patients with acute dyspnea: A multicenter study. Acta Radiol 2012;53: 885–892. 3. Trovato GM, Rollo VC, Martines GF, et al: Thoracic ultrasound in the differential diagnosis of severe dyspnea: A reappraisal. Int J Cardiol 2013;167:1081–1083. 4. Sperandeo M, Varriale A, Sperandeo G, et al: Transthoracic ultrasound in the evaluation of pulmonary fibrosis: Our experience. Ultrasound Med Biol 2009;35:723. 5. Moazedi-Fuerst FC, Zechner PM, Tripolt NJ, et al: Pulmonary echography in systemic sclerosis. Clin Rheumatol 2012;31:1621–1625. 6. Sperandeo M, Varriale A, Sperandeo G, et al: Characterization of the normal pulmonary surface and pneumo-
7. 8. 9. 10.
nectomy space by reflected ultrasound. J Ultrasound 2011;14:22–27. Soldati G, Copetti R, Sher S: Can lung comets be counted as “objects”? JACC Cardiovasc Imaging 2011;4: 438–439. Trovato GM, Sperandeo M: Sounds, ultrasounds, and artifacts: Which clinical role for lung imaging? Am J Respir Crit Care Med 2013;187:780–781. Trovato GM, Catalano D, Martines GF, et al: Is it time to measure lung water by ultrasound? Intensive Care Med 2013;39:1662. Platz E, Lattanzi A, Agbo C, et al: Utility of lung ultrasound in predicting pulmonary and cardiac pressures. Eur J Heart Fail 2012;14:1276–1284.
407
Echocardiography
LETTER TO THE EDITOR
Echocardiographic and Lung Ultrasound Characteristics in Ambulatory Patients with Dyspnea or Prior Heart Failure Dear Editor, The article by Platz et al.1 investigates the association of sonographic B-lines, a stated marker of extra-vascular lung water, with cardiac structure and function. The study was performed in a relatively stable outpatient population undergoing transthoracic echocardiography and lung ultrasound imaging (LUS). The count of B-lines, which are “artifacts,” is the diagnostic target, which, in our experience, appears inappropriate.2 B-lines are visible and approximately measured in conditions different from pulmonary congestion, and notably in chronic obstructive pulmonary disease3and pulmonary fibrosis4,5: it is a challenge to “count” them, being not an actual “measurement.”6,7 However, the main concern is related to the methodology. The most relevant reference studies, quoted also by the authors, did not use phased array transducers,1 but linear or convex probes. This makes all the difference as the number of B-lines is greater when using such transducers, particularly at the lower frequencies.2 We perform yearly intraobserver/inter-observer variability assessments of several US measurements, and repeat them each year at the end of our institutional postgraduate course in Clinical Ultrasound. A convex multifrequency 2-8 mHz probe was used with a MyLab Twice-ElaXto Ultrasound equipment (Esaote-Biomedica, Genoa, Italy). In 2013, in a sample of 20 MDs, with >5 years US practice and expertise (10 operators) or with 6 months of training in clinical US (10 operators), we asked them to assess twice the same movie clips of LUS with B-lines in 5 different clinical conditions; a fair intra-observer internal consistency is observed and the standard deviation is around 33.0% of the averages for each condition, considering the reports of all observers. Nonetheless, ranges of the B-lines individual counts are exceedingly wide for identical cases of each condition: pulmonary edema (3–10), chronic obstructive pulmonary disease exacerbation (4–10), pulmonary fibrosis (3–11), pleural effusion in congestive heart failure (HF) (3–10), pulmonary cancer lymphangitis (4–10). Which is the range for any measurement that the observers reported in the 406
cases studied by Platz et al.?1 Overall, the straightforward use of B-lines as “quantitative” measurements of B-lines is questionable. But the greater weakness is in cardiological data presentation and interpretation. (1) the most relevant correlation (not association as stated by the authors) is between B-lines count and LV mass index (g/m2): does it mean that we are dealing with a relationship of B-lines with left ventricular hypertrophy? (2) information on measures of left ventricular relaxation are available1: comments on the missing relationship of “lung congestion measures” with mechanisms involving left ventricular compliance should be interesting; (3) authors previously reported that “each additional B-line was associated with an increase in pulmonary artery systolic pressure of 1 mmHg”10 even if in the current noninvasive study relationship is weaker than with invasively measured cardiac pressures1: we could reasonably envisage effects deriving from inter-observer variability. It is difficult to agree with the authors’ overconfident conclusion: “sonographic B-lines in patients with HF should be thought of on a more continuous spectrum, similar to biomarkers, rather than a binary test to rule in (or out) acute pulmonary edema.” We, differently, prefer to rely on objective imaging achieved by lung ultrasound, such as pleural effusion, and on echocardiographic quantitative, objective, and reproducible measures, more than on nonspecific artifacts, as B-lines are.8,9 Guglielmo M. Trovato, M.D.,* Daniela Catalano, M.D.,* and Marco Sperandeo, M.D.† *Department of Medical and Pediatric Sciences, University of Catania, Catania, Italy †Department of Internal Medicine, IRCCS Casa Sollievo della Sofferenza Hospital, San Giovanni Rotondo, Italy References 1. Platz E, Hempel D, Pivetta E, et al: Echocardiographic and lung ultrasound characteristics in ambulatory patients with dyspnea or prior heart failure. Echocardiography 2014;31:133–139.
Letter to the Editor
2. Sperandeo M, Varriale A, Sperandeo G, et al: Assessment of ultrasound acoustic artifacts in patients with acute dyspnea: A multicenter study. Acta Radiol 2012;53: 885–892. 3. Trovato GM, Rollo VC, Martines GF, et al: Thoracic ultrasound in the differential diagnosis of severe dyspnea: A reappraisal. Int J Cardiol 2013;167:1081–1083. 4. Sperandeo M, Varriale A, Sperandeo G, et al: Transthoracic ultrasound in the evaluation of pulmonary fibrosis: Our experience. Ultrasound Med Biol 2009;35:723. 5. Moazedi-Fuerst FC, Zechner PM, Tripolt NJ, et al: Pulmonary echography in systemic sclerosis. Clin Rheumatol 2012;31:1621–1625. 6. Sperandeo M, Varriale A, Sperandeo G, et al: Characterization of the normal pulmonary surface and pneumo-
7. 8. 9. 10.
nectomy space by reflected ultrasound. J Ultrasound 2011;14:22–27. Soldati G, Copetti R, Sher S: Can lung comets be counted as “objects”? JACC Cardiovasc Imaging 2011;4: 438–439. Trovato GM, Sperandeo M: Sounds, ultrasounds, and artifacts: Which clinical role for lung imaging? Am J Respir Crit Care Med 2013;187:780–781. Trovato GM, Catalano D, Martines GF, et al: Is it time to measure lung water by ultrasound? Intensive Care Med 2013;39:1662. Platz E, Lattanzi A, Agbo C, et al: Utility of lung ultrasound in predicting pulmonary and cardiac pressures. Eur J Heart Fail 2012;14:1276–1284.
407
