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Patent foramen ovale diagnosed by contrast transesophageal echocardiography: is it really there?
Patent Foramen Ovale Diagnosed by Contrast Transesophageal Echocardiography: Is It Really There? Bruce Kleinman, MD, Ulana Leskiw, MD, William Jacobs, MD, and Taqdees Sheikh, MD
A
69-YEAR-OLD woman presented for coronary artery bypass surgery. She had an ejection fraction of 25%. Monitors included a pulmonary artery catheter as well as a transesophageal echocardiogram (TEE). TEE (Accuson, 128/ XP, Mountain View, CA) was performed after the induction of general anesthesia. An atrial septal aneurysm (ASA) was seen on the 4-chamber view (Fig 1). Because of the association of ASA and patent foramen ovale (PFO), a bubble contrast study was performed. This was done by injecting agitated saline at end-inspiration after the application of 20 cmH2O positive airway pressure. The airway pressure was released when the
Fig 2. Transesophageal echocardiogram, 4-chamber view. After injection of agitated saline the right atrium (RA) is completely opacified. LA, left atrium.
Fig 1. Transesophageal echocardiogram, 4-chamber view, showing the atrial septal aneurysm (highlighted by arrows). RA, right atrium; LA, left atrium.
From the Departments of Anesthesiology; and Medicine, Division of Cardiology, Stritch School of Medicine, Loyola University Medical Center, Maywood, IL. Address reprint requests to Bruce Kleinman, MD, Department of Anesthesiology, Stritch School of Medicine, Loyola University Medical Center, 2160 South First Avenue, Maywood, IL 60153. E-mail: [email protected] © 2003 Elsevier Inc. All rights reserved. 1053-0770/03/1704-0000$30.00/0 doi:10.1016/S1053-0770(03)00165-4 Key words: atrial septal aneurysm, patent foramen ovale, echo contrast, cardiac shunt, bubble contrast
552
Fig 3. Transesophageal echocardiogram, 4-chamber view. A few contrast echoes are seen in the left atrium (LA) after injection of agitated saline into the right atrium (RA). The arrows point out 3 of them.
right atrium was completely opacified (Fig 2). After 2 heartbeats, contrast echoes were seen in the left atrium (Fig 3). The surgeons were informed of this finding. Once cardiopulmonary bypass was initiated, the atrium was opened. Was there a PFO in this patient?
Journal of Cardiothoracic and Vascular Anesthesia, Vol 17, No 4 (August), 2003: pp 552-554
DIAGNOSTIC DILEMMA
553
DIAGNOSIS: SPONTANEOUS ECHO CONTRAST IN THE LEFT ATRIUM—NO PFO FOUND AT SURGERY
Over half of patients with ASAs have interatrial shunting as determined by TEE.1,2 The shunt is usually across an atrial septal defect, patent foramen ovale, or sinus venosus defect.1,2 So, it is important when an ASA is seen to have a high index of suspicion for a concomitant interatrial shunt. Shunt is diagnosed in 1 of 2 ways echocardiographically. A Doppler flow signal signifying shunt depends on the existence of a pressure difference between right and left atria. Because the pressure difference between the 2 atria is normally small, the subsequent Doppler shift is likewise small and may be difficult to detect.3 On the other hand, contrast echocardiography relies on the sonic reflective capacity of micro air bubbles passing across the interatrial septum. Detection of microbubbles is dependent on the volume of shunt flow.3 Bubble contrast echocardiography is similar to any other diagnostic test in that its validity in diagnosing interatrial shunt must be measured against a verification (“gold”) standard. The verification standard is anatomic correlation, or absent of that, catheterization. Most echocardiographers and cardiac anesthesiologists are concerned about the incidence of false negatives (ie, the interatrial shunt is present but the authors fail to make the diagnosis). False negatives are well documented.4 Few clinicians have considered the possibility of false-positive contrast echocardiography. In fact, the general belief is that a positive test is definitive.4 In one of the few studies in the literature that actually used anatomic correlation and catheterization data to verify the accuracy of bubble contrast echocardiography in diagnosing interatrial shunt, the false-positive rate was 5% (1 patient out of a total of 20 patients).5 The lone false-positive occurred in a patient with a right atrial myxoma. When the myxoma was removed at surgery, a repeat bubble contrast echocardiographic study was negative.5 This finding suggested that there was communication between right and left atria in some way involving the tumor. Recent investigations have suggested that echoes similar to the echoes generated by agitated saline can occur spontaneously in the heart despite appropriate gain and power settings.6,7 These echoes are generally less intense (acoustically bright) than the echoes generated by agitated saline. However, 6% are indistinguishable from echoes generated by agitated saline.6 The incidence of these echoes ranges from 9% during quiet respiration to 60% with provocative maneuvers such as valsalva, with 36% appearing in the left atrium.6 The origins of these spontaneous echoes in the left atrium are speculative. Conceivably, they could represent
gas from the right side of the heart (microbubbles from an intravenous infusion for example) translocating across the pulmonary vasculature. On the other hand, these signals could be a manifestation of the cavitation effect (gas coming out of solution as a result of abrupt pressure changes induced by the sudden release of valsalva or equivalent maneuvers). A recent report attributed the unexpected appearance of microbubbles in the left ventricle to the transport of microbubbles from the right side of the heart to the left via the Thebesian venous system.8 This explanation is certainly possible in this case, although Thebesian veins have only rarely been documented in the left atrium.9 Certainly, it is possible that the surgeon was unable to show a PFO that was in fact present. However, given that the operative surgeon in this case was one with 25 years of clinical practice, the authors believe that is unlikely. Two technical aspects, if performed in this case, might have further clarified this case dilemma. First, the authors used the 4-chamber view to visualize the interatrial septum. However, the bicaval 90° view is in fact better at actually visualizing the location of the opening in the septum if present.10 By actually visualizing the defect, the anesthesiologist might be helpful to the surgeon by pointing out the location of the defect upon opening the heart, rather than having the surgeon open the heart and have no clue as to where the potential defect is, as in this case. Hence, the failure of the surgeon to find the defect may have been due not to the fact that it was not present but rather to the fact that the surgeon was not given echocardiographic guidance by the anesthesiologist. If, on the other hand, no defect is seen on the bicaval view, but bubbles still appear in the left atrium after contrast injection, the bicaval view may still offer an advantage over the 4-chamber view in that it may better delineate where the bubbles are coming from (ie, right upper pulmonary veins).11 Second, it would have been quite helpful if the authors performed the airway pressure application and release maneuver before the agitated saline injection. This would have determined if spontaneous contrast echoes were present to begin with. If so, the authors could then have attributed the false-positive finding to the presence of spontaneous echoes. But this was not done; the authors suspect most clinicians do not. So, the lessons from this case are 2-fold. First, the anesthesiologist should perform a Valsalva maneuver or its positive-pressure equivalent, on the patient, and check for spontaneous contrast echoes before contrast injection. Second, when a PFO is suspected, it is not enough to show contrast within the left atrium, but rather the potential anatomic defect in the interatrial septum should be sought by using the bicaval view.
REFERENCES 1. Zhao BW, Mizushige K, Xian TC, et al: Incidence and clinical significance of interatrial shunting in patients with atrial septal aneurysm detected by contrast transesophageal echocardiography. Angiology 50:745-753, 1999 2. Mugge A, Daniel WG, Angermann C, et al: Atrial septal aneurysm in adult patients. A multicenter study using transthoracic and transesophageal echocardiography. Circulation 91:2785-2792, 1995
3. Konstadt SN, Louie EK, Black S, et al: Intraoperative detection of patent foramen ovale by transesophageal echocardiography. Anesthesiology 74:212-216, 1991 4. Rafferty TD: Intraoperative transesophageal saline-contrast imaging of flow-patent foramen ovale. Anesth Analg 75:475-480, 1992 5. Chen WJ, Kuan P, Lien WP, et al: Detection of patent foramen ovale by contrast transesophageal echocardiography. Chest 101:15151520, 1992
554
6. Kim HH, Tam JW, Chan KL: A prospective transesophageal echocardiographic study to assess a new type of left atrial spontaneous contrast at rest and during respiratory manoeuvers. Can J Cardiol 15:1217-1222, 1999 7. Van Camp G, Cosyns B, Vandenbossche JL: Non-smoke spontaneous contrast in left atrium intensified by respiratory manoeuvers: A new transoesophageal echocardiographic observation. Br Heart J 72: 446-451, 1994 8. Akhtar S, Lluberes V, Allen K, et al: Unexpected, transesophageal echocardiography-detected left ventricular microbubbles during off-pump coronary artery bypass graft surgery. J Cardiothorac Vasc Anesth 15:131-133, 2001
KLEINMAN ET AL
9. Williams PL, Warwick R, Dyson M, et al: Gray’s Anatomy (ed 37). New York, NY, Churchill Livingstone, 1989, pp 793 10. Chenzbraun A, Pinto FJ, Schnittger I: Biplane transesophageal echocardiography in the diagnosis of patent foramen ovale. J Am Soc Echocardiogr 6:417-421, 1993 11. Shanewise JS, Cheung AT, Aronson S, et al: ASE/SCA guidelines for performing a comprehensive multiple transesophageal echocardiography examination: Recommendations of the American Society of Echocardiography Council for Intraoperative Echocardiography and the Society of Cardiovascular Anesthesiologists task force for certification in perioperative transesophageal echocardiography. Anesth Analg 89:870-884, 1999
A
69-YEAR-OLD woman presented for coronary artery bypass surgery. She had an ejection fraction of 25%. Monitors included a pulmonary artery catheter as well as a transesophageal echocardiogram (TEE). TEE (Accuson, 128/ XP, Mountain View, CA) was performed after the induction of general anesthesia. An atrial septal aneurysm (ASA) was seen on the 4-chamber view (Fig 1). Because of the association of ASA and patent foramen ovale (PFO), a bubble contrast study was performed. This was done by injecting agitated saline at end-inspiration after the application of 20 cmH2O positive airway pressure. The airway pressure was released when the
Fig 2. Transesophageal echocardiogram, 4-chamber view. After injection of agitated saline the right atrium (RA) is completely opacified. LA, left atrium.
Fig 1. Transesophageal echocardiogram, 4-chamber view, showing the atrial septal aneurysm (highlighted by arrows). RA, right atrium; LA, left atrium.
From the Departments of Anesthesiology; and Medicine, Division of Cardiology, Stritch School of Medicine, Loyola University Medical Center, Maywood, IL. Address reprint requests to Bruce Kleinman, MD, Department of Anesthesiology, Stritch School of Medicine, Loyola University Medical Center, 2160 South First Avenue, Maywood, IL 60153. E-mail: [email protected] © 2003 Elsevier Inc. All rights reserved. 1053-0770/03/1704-0000$30.00/0 doi:10.1016/S1053-0770(03)00165-4 Key words: atrial septal aneurysm, patent foramen ovale, echo contrast, cardiac shunt, bubble contrast
552
Fig 3. Transesophageal echocardiogram, 4-chamber view. A few contrast echoes are seen in the left atrium (LA) after injection of agitated saline into the right atrium (RA). The arrows point out 3 of them.
right atrium was completely opacified (Fig 2). After 2 heartbeats, contrast echoes were seen in the left atrium (Fig 3). The surgeons were informed of this finding. Once cardiopulmonary bypass was initiated, the atrium was opened. Was there a PFO in this patient?
Journal of Cardiothoracic and Vascular Anesthesia, Vol 17, No 4 (August), 2003: pp 552-554
DIAGNOSTIC DILEMMA
553
DIAGNOSIS: SPONTANEOUS ECHO CONTRAST IN THE LEFT ATRIUM—NO PFO FOUND AT SURGERY
Over half of patients with ASAs have interatrial shunting as determined by TEE.1,2 The shunt is usually across an atrial septal defect, patent foramen ovale, or sinus venosus defect.1,2 So, it is important when an ASA is seen to have a high index of suspicion for a concomitant interatrial shunt. Shunt is diagnosed in 1 of 2 ways echocardiographically. A Doppler flow signal signifying shunt depends on the existence of a pressure difference between right and left atria. Because the pressure difference between the 2 atria is normally small, the subsequent Doppler shift is likewise small and may be difficult to detect.3 On the other hand, contrast echocardiography relies on the sonic reflective capacity of micro air bubbles passing across the interatrial septum. Detection of microbubbles is dependent on the volume of shunt flow.3 Bubble contrast echocardiography is similar to any other diagnostic test in that its validity in diagnosing interatrial shunt must be measured against a verification (“gold”) standard. The verification standard is anatomic correlation, or absent of that, catheterization. Most echocardiographers and cardiac anesthesiologists are concerned about the incidence of false negatives (ie, the interatrial shunt is present but the authors fail to make the diagnosis). False negatives are well documented.4 Few clinicians have considered the possibility of false-positive contrast echocardiography. In fact, the general belief is that a positive test is definitive.4 In one of the few studies in the literature that actually used anatomic correlation and catheterization data to verify the accuracy of bubble contrast echocardiography in diagnosing interatrial shunt, the false-positive rate was 5% (1 patient out of a total of 20 patients).5 The lone false-positive occurred in a patient with a right atrial myxoma. When the myxoma was removed at surgery, a repeat bubble contrast echocardiographic study was negative.5 This finding suggested that there was communication between right and left atria in some way involving the tumor. Recent investigations have suggested that echoes similar to the echoes generated by agitated saline can occur spontaneously in the heart despite appropriate gain and power settings.6,7 These echoes are generally less intense (acoustically bright) than the echoes generated by agitated saline. However, 6% are indistinguishable from echoes generated by agitated saline.6 The incidence of these echoes ranges from 9% during quiet respiration to 60% with provocative maneuvers such as valsalva, with 36% appearing in the left atrium.6 The origins of these spontaneous echoes in the left atrium are speculative. Conceivably, they could represent
gas from the right side of the heart (microbubbles from an intravenous infusion for example) translocating across the pulmonary vasculature. On the other hand, these signals could be a manifestation of the cavitation effect (gas coming out of solution as a result of abrupt pressure changes induced by the sudden release of valsalva or equivalent maneuvers). A recent report attributed the unexpected appearance of microbubbles in the left ventricle to the transport of microbubbles from the right side of the heart to the left via the Thebesian venous system.8 This explanation is certainly possible in this case, although Thebesian veins have only rarely been documented in the left atrium.9 Certainly, it is possible that the surgeon was unable to show a PFO that was in fact present. However, given that the operative surgeon in this case was one with 25 years of clinical practice, the authors believe that is unlikely. Two technical aspects, if performed in this case, might have further clarified this case dilemma. First, the authors used the 4-chamber view to visualize the interatrial septum. However, the bicaval 90° view is in fact better at actually visualizing the location of the opening in the septum if present.10 By actually visualizing the defect, the anesthesiologist might be helpful to the surgeon by pointing out the location of the defect upon opening the heart, rather than having the surgeon open the heart and have no clue as to where the potential defect is, as in this case. Hence, the failure of the surgeon to find the defect may have been due not to the fact that it was not present but rather to the fact that the surgeon was not given echocardiographic guidance by the anesthesiologist. If, on the other hand, no defect is seen on the bicaval view, but bubbles still appear in the left atrium after contrast injection, the bicaval view may still offer an advantage over the 4-chamber view in that it may better delineate where the bubbles are coming from (ie, right upper pulmonary veins).11 Second, it would have been quite helpful if the authors performed the airway pressure application and release maneuver before the agitated saline injection. This would have determined if spontaneous contrast echoes were present to begin with. If so, the authors could then have attributed the false-positive finding to the presence of spontaneous echoes. But this was not done; the authors suspect most clinicians do not. So, the lessons from this case are 2-fold. First, the anesthesiologist should perform a Valsalva maneuver or its positive-pressure equivalent, on the patient, and check for spontaneous contrast echoes before contrast injection. Second, when a PFO is suspected, it is not enough to show contrast within the left atrium, but rather the potential anatomic defect in the interatrial septum should be sought by using the bicaval view.
REFERENCES 1. Zhao BW, Mizushige K, Xian TC, et al: Incidence and clinical significance of interatrial shunting in patients with atrial septal aneurysm detected by contrast transesophageal echocardiography. Angiology 50:745-753, 1999 2. Mugge A, Daniel WG, Angermann C, et al: Atrial septal aneurysm in adult patients. A multicenter study using transthoracic and transesophageal echocardiography. Circulation 91:2785-2792, 1995
3. Konstadt SN, Louie EK, Black S, et al: Intraoperative detection of patent foramen ovale by transesophageal echocardiography. Anesthesiology 74:212-216, 1991 4. Rafferty TD: Intraoperative transesophageal saline-contrast imaging of flow-patent foramen ovale. Anesth Analg 75:475-480, 1992 5. Chen WJ, Kuan P, Lien WP, et al: Detection of patent foramen ovale by contrast transesophageal echocardiography. Chest 101:15151520, 1992
554
6. Kim HH, Tam JW, Chan KL: A prospective transesophageal echocardiographic study to assess a new type of left atrial spontaneous contrast at rest and during respiratory manoeuvers. Can J Cardiol 15:1217-1222, 1999 7. Van Camp G, Cosyns B, Vandenbossche JL: Non-smoke spontaneous contrast in left atrium intensified by respiratory manoeuvers: A new transoesophageal echocardiographic observation. Br Heart J 72: 446-451, 1994 8. Akhtar S, Lluberes V, Allen K, et al: Unexpected, transesophageal echocardiography-detected left ventricular microbubbles during off-pump coronary artery bypass graft surgery. J Cardiothorac Vasc Anesth 15:131-133, 2001
KLEINMAN ET AL
9. Williams PL, Warwick R, Dyson M, et al: Gray’s Anatomy (ed 37). New York, NY, Churchill Livingstone, 1989, pp 793 10. Chenzbraun A, Pinto FJ, Schnittger I: Biplane transesophageal echocardiography in the diagnosis of patent foramen ovale. J Am Soc Echocardiogr 6:417-421, 1993 11. Shanewise JS, Cheung AT, Aronson S, et al: ASE/SCA guidelines for performing a comprehensive multiple transesophageal echocardiography examination: Recommendations of the American Society of Echocardiography Council for Intraoperative Echocardiography and the Society of Cardiovascular Anesthesiologists task force for certification in perioperative transesophageal echocardiography. Anesth Analg 89:870-884, 1999