Catheterization and Cardiovascular Diagnosis 26:122-126 (1992)
Prolapsing Large Aneurysm of the Atrial Septum Simulating a Right Atrial Mass Paolo Angelini, MD, Susan Wilansky, MD, Carlos Gaos, MD, Ali Montazavi, MD, Enzo Boncompagni, MD, and Denton A. Cooley, MD An unusual case of a large, prolapsing atrial septal aneurysm in a patient with an otherwise normal heart is described. The aneurysm caused right atrial obstruction and r e suited in a “tumor effect.” The patient experienced debilitating symptoms for years before receiving an appropriate dlagnosis and curatlve surgical treatment. 8 1982 WllOy-UM, Im.
Key words: right atrlai obstruction, tumor effect, debilitating symptoms
INTRODUCTION
Aneurysm of the atrial septum has been clinically described only during the last 15 years [l], in both the pediatric [2-71 and adult populations [8-261. This has been made possible since the introduction of bidimensional echocardiography. The first anatomic description of atrial septal aneurysm (ASA) in the English literature was by Lev and associates in 1938 [27]; still, only a few anatomic descriptions and surgical reports are available [28-321. ASA seems to occur at variable rates in different age groups. Apparently, it is frequently observed in fetuses studied by echocardiography for atrial arrhythmias (64% of 23 cases [31], or for ruling out congenital heart disease (26% of 66 cases [33]). The incidence decreases to about 1-2% [3,5,34,35] in a pediatric cardiology population. In a continuous series of autopsies, ASA was found in 16 of 1578 cases [36]. In a general population of adults undergoing echocardiography for various reasons, the incidence was between 0.12% and 0.57% [ 12,13,15,16]. Longitudinal studies of babies born with ASA suggest that both growth and the correction of hemodynamic abnormalities (Like spontaneous or surgical closure of atrial septal defects) are associated with the disappearance of ASA [7,3,34,35]. On the contrary, in adults ASA tends to be encountered in association with atrial septal defects [ 12,13,34], mitral valve prolapse [ 12-14,20,21,3 13, right atrial hypertension as seen in tricuspid atresia [4,6] or pulmonary atresia with an intact ventricular septum [2,3] or left atrial hypertension like that observed in mitral stenosis [12]. Its occurrence is unusual, however, in a person with an otherwise normal heart [9,12,20]. The unusual case of ASA we describe here occurred in such a patient with a large prolapsing aneurysm that caused right atrial obstruction and produced a tumor effect. The 0 1992 Wiley-Liss, Inc.
patient experienced progressive debilitating symptoms for years before receiving an appropriate diagnosis and curative surgical treatment. CASE REPORT
A 46-yr-old woman from Italy was admitted to St. Luke’s Episcopal Hospital for diagnostic evaluation in April 1991. Since birth, she had been diagnosed with some cardiac abnormalities. The initial and most predominant of her symptoms was dyspnea. Other symptoms, including easy fatiguability, palpitations, chest pain, and retrosternal pressure, had rendered her incapble of doing more than mild physical exercise. Five years before her admission to St. Luke’s, she had experienced several episodes of near collapse, accompanied by chest pain. No signs of congestive heart failure had been documented. An electrocardiographic study with a mild stress test performed in Italy in 1986 had been suggestive of ischemia. Heart catheterization performed at that time led to the diagnosis of a small atrial septal defect. In recent years, the patient had undergone several echocardiographic tests, which were inconclusive. Despite the use of digitalis and diuretics during a 12-yr period before 1991, her symptoms were never ade-
From the Departments of Adult Cardiology and Cardiovascular Surgery, Texas Heart institute and St. Luke’s Episcopal Hospital, Houston, Texas. Received September 27, 1 9 9 1 ; revision accepted December 1 , 1991. Address reprint requests to Dr. Paolo Angelini, P.O. Box 20206, Houston, TX 17225.
Aneurysm of the Atrial Septum
123
Fig. 1. Transesophageal view in the longitudinal plane. Right atrium (RA) in diastole (left) and systole (right). Note almost complete obliteration of the right atrial cavlty in systole. IAS, interatrial septum; LA, left atrium; RV, rlght ventricle.
quately controlled. She presented in New York Heart Association functional class 111. Upon admission, the patient looked pale and dusky, and she was slightly malnourished. She had experienced profound fatigue during the 3 days following her trip from Italy. Again, there were no signs of congestive heart failure. Blood pressure was 130/80 mm Hg, and the resting heart rate was 88 B/min. An obvious right ventricular (overdynamic) heave was present on precordial exploration, and a soft systolic murmur was detected in the area of the tricuspid valve. The second heart sound was widely and variably split. A midsystolic click was present at the apex and midprecordium. The electrocardiogram, which had remained unchanged over the years, showed peaked P waves, incomplete right bundle branch block, and nonspecific ST-T changes. Chest X rays revealed a normal heart size and normal pulmonary vascular markings. EchocardiographicStudies
Two-dimensional echocardiography revealed normal size and function of the heart chambers. An ill-defined linear structure was seen in the right atrium on apical
four-chamber and subcostal views. Transesophageal echocardiography revealed this structure to be an extremely mobile interatrial septa1 aneurysm, which prolapsed into the right atrium and resulted in variable obstruction (Fig. 1). Color flow Doppler examination of the right atrium showed systolic turbulent flow at the aneurysm and diastolic laminar flow at the tricuspid valve. Pulsed Doppler echocardiography shown bidirectional flow across the atrial septum throughout the entire extent of the aneurysm, suggesting the presence of multiple fenestrations. Agitated saline (10 cc) injected through the right brachial vein showed a crossover of microcavitations along the entire length of the aneurysm into the left atrium. The pulmonary veins drained normally into the left atrium. Exercise Stress Testing During a treadmill test in which a modified Bruce protocol was used, the patient experienced palpitations, chest pain, and shortness of breath. Her heart rate was 90 B/min in the resting phase, 110 B/min in an upright resting position, and 135 B/min at 1 minute of mild exercise (0% elevation, 2.5 MPH). She was unable to
124
Angelini et al. TABLE 1. Pressures and Oxygen Saturation in the Cardlac Cavltles. Hemodynamic data 0 2
Site RA
svc IVC RV MPA LV A0 LA
Pressures (mm He3
saturation
a = 9,v = 9,m = 7 a = 9,v = 9,m = I a = 9.v = 9.m = 7 261 1-7 26/10, fl 180/0-12 180/100, 3 3 a = 12, v = 10, m = 7
77 74 79 81 80 94 94 94
Follow-Up
At 6-month follow-up, the patient’s condition was normalized. She had returned to work, and she reported relief of all preoperative cardiovascular symptoms.
(%)
“AO. aorta; IVC, inferior vena cava; LA, left
atrium; LV, left ventricle; MPA. main pulmonary artery; RA, right atrium; RV, right ventricle: SVC. superior vena cava.
increase her heart rate during the next 4 minutes and stopped exercising with a maximal blood pressure of 110/80 mm Hg (1 10/80 mm Hg at rest) and nonspecific ST-T changes. Oxygen capillary saturation was monitored throughout the test by an electronic digital sensor and remained normal (98-99%). Cardiac Catheterization
Pressures and oxygen saturations were obtained during a right and left heart catheterization (Table I). The right heart catheter could be passed from different points of the atrial septum into the left atrium, the right and left pulmonary veins, and the left ventricle. Angiography confirmed the presence of a small atrial septal defect with a calculated left-to-right shunt of 1.4: 1 .O. Pulmonary venous drainage was normal. Right pulmonary artery and vein angiographic studies revealed evidence of a large ASA prolapsing into the right atrium. Even with few hemodynamic signs of severe cardiac decompensation, we believed that this patient’s symptoms were primarily organic and were due to right ventricular inlet obstruction by the prolapsing septal aneurysm. Therefore, surgical repair was recommended. Surgical/PathologicaI Findings
At surgery, a large (4.0 X 5.0 cm) fossa ovalis aneurysm was found, bulging into the right atrium. The aneurysm was replete with fenestrations. Microscopy of the atrial septal tissue showed myxoid degeneration with increased interstitial collagen. No other defect was noted at surgery. The ASA was resected, the atrial septum was repaired by patch, and there were no postoperative complications. The patient was discharged on the 8th postoperative day, with no residual extra heart sounds or murmurs.
DISCUSSION
This unusual case illustrates a pathological entity that has not been previously described, namely, right atrial obstruction from a protruding large ASA in an otherwise normal heart. Differential diagnosis for any case involving symptoms similar to those found in this case should include other right atrial lesions such as right atrial myxoma and other tumors of the heart, cor triatriatum dexter, and right atrial clots. ASA is diagnosed essentially by echocardiography , even though with angiography a fairly high degree of assurance can be reached. Precise images of the aneurysm can be obtained by two-dimensional echocardiography, in different projections, by both the transthoracic and the transesophageal routes. Contrast echocardiography can enhance the imaging, and a Valsalva maneuver can frequently demonstrate the prolapse of the ASA from the right to the left atrium [4].Magnetic resonance imaging has also recently been shown to be quite demonstrative [ 5 ] . ASA appears to stem from two factors, each with varying importance depending on the case: 1) the thickness, stiffness, or compliance of the fossa ovalis; and 2) the pressure gradient between the atrial cavities. In cases of very thin, compliant fossa ovalis tissue, the normally higher pressure in the left atrium would cause the fossa ovalis to prolapse into the right atrium. In cases with a marked increase in atrial pressure (as in tricuspid atresia with obstructive atrial septal defect), a minor increase in the fossa ovalis compliance would cause it to prolapse. The histologic findings in our case suggest that myxoid degeneration of the fossa ovalis tissue could be an important condition predisposing to ASA and explaining its association with mitral valve prolapse [31]. Abnormal physical findings associated with ASA have been described in the literature, but not substantiated. In particular, the presence of systolic click [8] has been frequently reported; in some patients, however, it may be caused by mitral valve prolapse rather than by ASA alone. In our case, the systolic click disappeared after surgical correction of ASA. Since this patient did not have mitral valve prolapse, a direct relationship between the click and ASA is suggested. Heretofore, in addition to atrial arrhythmias [3,12,33], the clinical manifestations of ASA have been mainly related to the possibility [ 12,15,16,23,37] of systemic and pulmonary embolism. The unusual wide motion of
Aneurysm of the Atrial Septum
the atrial septum during respiration [37] and the Valsalva maneuver [38] could explain the mechanism of embolization of any thrombotic material that might attach itself to the ASA wall 1371. Our case report illustrates the possibility that ASA alone, particularly when it is large, can create serious functional disabilities, mainly by obstructing the right ventricular inlet during exercise. The difficulty in objectively showing the importance of this mechanism is related to the absence of definite hemodynamic or Doppler signs of obstruction at rest. The absence of a significant resting gradient is probably justified by both the low pressure regimen in the right atrium (tricuspid stenosis or atrial myxoma of clinical importance may also cause relatively mild gradients) and the peculiar situation of this right atrial mass, caudal to the superior vena cava but cranial to the inferior vena cava flow. Exercise testing with Doppler echocardiography could have been more revealing and should be done in future similar cases. Easy fatiguability and dyspnea were most probably related to this pathophysiological change in our patient. Another mechanism of functional limitation, suggested by our case, is the nonspecific cardiac tumor effect. Indeed, a mass moving inside the heart tends to be perceived by the patient as chest pressure, pain, or palpitations: a vague sense of abnormal heart function. It is interesting to note that our patient had had several consultations from different physicians and that the majority favored the diagnosis of cardiac neurosis or neurasthenia. However, she was cured by resection of the ASA . ACKNOWLEDGMENTS
The authors thank Rebecca Teaff, Section of Scientific Publications, Texas Heart Institute, for editorial assistance with this article. REFERENCES Freedom R, Rowe R: Aneurysm of the atrial septum in tricuspid atresia: diagnosis during life and therapy. Am J Cardiol 32:265, 1976. Sahn DJ: Allen HD, Anderson R, Goldberg SJ: Echocardiographic diagnosis of atrial septal aneurysm in an infant with hypoplastic right heart syndrome. Chest 73:227, 1978. Wolf WJ, Casta A, Sapire DW: Atrial septal aneurysms in infants and children. Am Heart J 113:1149, 1987. Reder RF, Yeh HC, Steinfeld L: Aneurysm of the interatrial septum causing pulmonary venous obstruction in an infant with tricuspid atresia. Am Heart J 102:786, 1981. Topaz 0, Feigl A, Edwards JE: Aneurysm of the fossa ovalis in infants: a pathologic study. Pediatr Cardiol 6:65-68, 1985. 6. Casta A, Casta DI Sapire-DW, Swischuk L: True congenital aneurysm of the septum primum not associated with obstructive right or left-sided lesions, identified by two-dimensional echocar-
125
diography and angiography in the newborn. Pediatr Cardiol 4: 159-162, 1983. 7. Awan IH, Rice R, Moodie DS: Spontaneous closure of atrial septal defect with interatrial aneurysm formation. Pediatr Cardiol 3:143-145, 1982. 8. Alexander MD, Bloom KR, Hart P, D’Silva F, Murgo J: Atrial septal aneurysm: A cause for midsystolic click. Report of a case and review of the literature. Circulation 63:1186-1188, 1981. 9. Lazar AV, Pechacek LW, Mihalick MJ, DeCastro CM, Hall RJ: Aneurysm of the interatrial septum occurring as an isolated anomaly. Cathet Cardiovasc Diagn 9:167-173, 1983. 10. Hauser AM, Timmis GC, Stewart JR, Ramos RG, Gangadharen V, Westveer DC, Gordon S: Aneurysm of the atrial septum as diagnosed by echocardiography: analysis of 11 patients. Am J Cardiol 54:1401-1402, 1984. I I . Anderson GJ, Swartz J: Two-dimensional echocardiographic recognition of an atrial septal aneurysm. Int J Cardiol 2:447-449, 1983. 12. Hanley PC, Tajik AJ, Hynes JK, Edwards WD, Reeder GS, Hagler DJ, Seward JB: Diagnosis and classification of atrial septal aneurysm by two-dimensional echocardiography: report of 80 consecutive cases. Am J Cardiol 6:1370-1382, 1985. 13. Longhini C, Brunazzi C , Musacci G, Caneva M, Bandello A, Bolomini L, Barbiero M, Toselli T, Barbaresi F: Atrial septal aneurysm-echopolycardiographic study. Am J Cardiol 56:653666, 1985. 14. Rahko PS, Xu QB: Increased prevalence of atrial septal aneurysm in mitral valve prolapse. Circulation 8O(Suppl 2):0037A, 1989. 15. Belkin RN, Hurwitz BJ, Kisslo J: Atrial septal aneurysm: association with cerebrovascular and peripheral embolic events. Stroke 18:856-862, 1987. 16. Gallet B, Malergue MC, Adams C, et al: Atrial septal aneurysm, a potential cause of systemic embolism: an echocardiographic study. Br Heart J 53:292-297, 1985. 17. Vandenbossche JL, Englert M: Effects of respiration on an atrial septal aneurysm of the fossa ovale shown by echographic study. Am Heart J 103:922-923, 1982. 18. Burton DA, Chin A, Weinberg PM, Pigott JD: Identification of cor triatriatum dexter by two-dimensional echocardiography. Am J Cardiol 60:409-410, 1987. 19. Ong LS, Nanda NC, Falkoff MD, Barold SS: Interatrial septal aneurysm, systolic click and atrial tachyarrhythmia-a new syndrome? Ultrasound Med Biol 8:691-693, 1982. 20. lliceto S, Papa A, Sorino M, Rizzon P Combined atrial septal aneurysm and mitral valve prolapse: detection by two-dimensional echocardiography. Am J Cardiol 54:1151-1153, 1984. 21. Abinader EG, Rokey R, Goldhammer E, Kuo LC, Said E: Prevalence of atrial septal aneurysm in patients with mitral valve prolapse. Am J Cardiol 62:1139-1140, 1988. 22. Gondi B, Nanda NC: Two-dimensional echocardiographic features of atrial septal aneurysms. Circulation 63:452-457, 1981. 23. Schneider B, Hanrath P, Vogel P, Meinertz T: Improved morphologic characterization of atrial septal aneurysm by transesophageal echocardiography: relation to cerebrovascular events. J Am Coll Cardiol 16:1000-1009, 1990. 24. Smith AJ, Panidis IP, Berger S, Gonzales R: Large atrial septal aneurysm mimicking a cystic right atrial mass. Am Heart J 120: 714-716, 1990. 25. Pena-Tizon FJ, Marin-Huerta E, Pey-Illera J: Aneurysm of atrial septum associated with rheumatic mitral stenosis simulating tumour of right atrium. Int J Cardiol 23:264-267, 1989. 26. Magherini A, Margiotta C , Bandini F, Simonetti L, Bartolozzi G: Atrial septal aneurysm, octasia of a sinus of Valsalva and mitral valve prolapse in Marfan’s syndrome. Am J Cardiol 58:172-173, 1986.
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27. Lev M. Saplir 0: Congenital aneurysm of the membranous septum. Arch Pathol 25:819-837, 1938. 28. Lang FJ, Posselt A: Aneuryematisch Vorwolburg der Fossa Ovalis in den Linken Vorhof. Wien Med Wochenschr 84392-392, 1934. 29. Pitts RM, Potts WJ: Congenital diverticulum of the left atrium. Arch Surg 84:334-336, 1962. 30. Morrow AG, Behrendt DM: Congenital aneurysm (diverticulum) of the right atrium. Circulation 38:124-128, 1968. 3 1. Roberts WC: Aneurysm (redundancy) of the atrial septum (fossa ovale membrane) and prolapse (redundancy) of the mitral valve. Am J Cardiol 54:1153-1154, 1984. 32. Thompson JI, Phillips LA, Melmon KL: Pseudotumor of the right atrium: report of a case and review of its etiology. Ann Intern Med 64:655-657, 1966. 33. Rice MJ, McDonald RW, Reller MD: Fetal atrial septal aneurysm: a cause of fetal atrial arrhythmias. J Am Coll Cardiol 12: 1292-1297, 1988.
34. Brand A, Keren A, Branski D, Abrahamov A, Stern S: Natural course of atrial septal aneurysm in children and the potential for spontaneous closure of associated septal defect. Am J Cardiol 64:996-1001, 1989. 35. Shiraishi I, Hamaoka K, Hayashi S, Koh E, Onouchi Z, Sawada T: Atrial septal aneurysm in infancy. Pediatr Cardiol 11:82-85, 1990. 36. Silver MD, Dorsey JS: Aneurysms of the septum primum in adults. Arch Pathol Lab Med 102:62-65, 1978. 37. Zabalgoitia-Reyes M, Herrera C, Gandhi DK, Mehlman DJ, McPherson DD, Talano JV: A possible mechanism for neurologic ischemic events in patients with atrial septal aneurysm. Am J Cardiol 66:761-764, 1990. 38. Haugland H, Vik-Mo H: Aneurysm of the atrial septum: motion pattern in relation to respiratory and cardiac cycles. J Clin Ultrasound 1452-54, 1986.
Prolapsing Large Aneurysm of the Atrial Septum Simulating a Right Atrial Mass Paolo Angelini, MD, Susan Wilansky, MD, Carlos Gaos, MD, Ali Montazavi, MD, Enzo Boncompagni, MD, and Denton A. Cooley, MD An unusual case of a large, prolapsing atrial septal aneurysm in a patient with an otherwise normal heart is described. The aneurysm caused right atrial obstruction and r e suited in a “tumor effect.” The patient experienced debilitating symptoms for years before receiving an appropriate dlagnosis and curatlve surgical treatment. 8 1982 WllOy-UM, Im.
Key words: right atrlai obstruction, tumor effect, debilitating symptoms
INTRODUCTION
Aneurysm of the atrial septum has been clinically described only during the last 15 years [l], in both the pediatric [2-71 and adult populations [8-261. This has been made possible since the introduction of bidimensional echocardiography. The first anatomic description of atrial septal aneurysm (ASA) in the English literature was by Lev and associates in 1938 [27]; still, only a few anatomic descriptions and surgical reports are available [28-321. ASA seems to occur at variable rates in different age groups. Apparently, it is frequently observed in fetuses studied by echocardiography for atrial arrhythmias (64% of 23 cases [31], or for ruling out congenital heart disease (26% of 66 cases [33]). The incidence decreases to about 1-2% [3,5,34,35] in a pediatric cardiology population. In a continuous series of autopsies, ASA was found in 16 of 1578 cases [36]. In a general population of adults undergoing echocardiography for various reasons, the incidence was between 0.12% and 0.57% [ 12,13,15,16]. Longitudinal studies of babies born with ASA suggest that both growth and the correction of hemodynamic abnormalities (Like spontaneous or surgical closure of atrial septal defects) are associated with the disappearance of ASA [7,3,34,35]. On the contrary, in adults ASA tends to be encountered in association with atrial septal defects [ 12,13,34], mitral valve prolapse [ 12-14,20,21,3 13, right atrial hypertension as seen in tricuspid atresia [4,6] or pulmonary atresia with an intact ventricular septum [2,3] or left atrial hypertension like that observed in mitral stenosis [12]. Its occurrence is unusual, however, in a person with an otherwise normal heart [9,12,20]. The unusual case of ASA we describe here occurred in such a patient with a large prolapsing aneurysm that caused right atrial obstruction and produced a tumor effect. The 0 1992 Wiley-Liss, Inc.
patient experienced progressive debilitating symptoms for years before receiving an appropriate diagnosis and curative surgical treatment. CASE REPORT
A 46-yr-old woman from Italy was admitted to St. Luke’s Episcopal Hospital for diagnostic evaluation in April 1991. Since birth, she had been diagnosed with some cardiac abnormalities. The initial and most predominant of her symptoms was dyspnea. Other symptoms, including easy fatiguability, palpitations, chest pain, and retrosternal pressure, had rendered her incapble of doing more than mild physical exercise. Five years before her admission to St. Luke’s, she had experienced several episodes of near collapse, accompanied by chest pain. No signs of congestive heart failure had been documented. An electrocardiographic study with a mild stress test performed in Italy in 1986 had been suggestive of ischemia. Heart catheterization performed at that time led to the diagnosis of a small atrial septal defect. In recent years, the patient had undergone several echocardiographic tests, which were inconclusive. Despite the use of digitalis and diuretics during a 12-yr period before 1991, her symptoms were never ade-
From the Departments of Adult Cardiology and Cardiovascular Surgery, Texas Heart institute and St. Luke’s Episcopal Hospital, Houston, Texas. Received September 27, 1 9 9 1 ; revision accepted December 1 , 1991. Address reprint requests to Dr. Paolo Angelini, P.O. Box 20206, Houston, TX 17225.
Aneurysm of the Atrial Septum
123
Fig. 1. Transesophageal view in the longitudinal plane. Right atrium (RA) in diastole (left) and systole (right). Note almost complete obliteration of the right atrial cavlty in systole. IAS, interatrial septum; LA, left atrium; RV, rlght ventricle.
quately controlled. She presented in New York Heart Association functional class 111. Upon admission, the patient looked pale and dusky, and she was slightly malnourished. She had experienced profound fatigue during the 3 days following her trip from Italy. Again, there were no signs of congestive heart failure. Blood pressure was 130/80 mm Hg, and the resting heart rate was 88 B/min. An obvious right ventricular (overdynamic) heave was present on precordial exploration, and a soft systolic murmur was detected in the area of the tricuspid valve. The second heart sound was widely and variably split. A midsystolic click was present at the apex and midprecordium. The electrocardiogram, which had remained unchanged over the years, showed peaked P waves, incomplete right bundle branch block, and nonspecific ST-T changes. Chest X rays revealed a normal heart size and normal pulmonary vascular markings. EchocardiographicStudies
Two-dimensional echocardiography revealed normal size and function of the heart chambers. An ill-defined linear structure was seen in the right atrium on apical
four-chamber and subcostal views. Transesophageal echocardiography revealed this structure to be an extremely mobile interatrial septa1 aneurysm, which prolapsed into the right atrium and resulted in variable obstruction (Fig. 1). Color flow Doppler examination of the right atrium showed systolic turbulent flow at the aneurysm and diastolic laminar flow at the tricuspid valve. Pulsed Doppler echocardiography shown bidirectional flow across the atrial septum throughout the entire extent of the aneurysm, suggesting the presence of multiple fenestrations. Agitated saline (10 cc) injected through the right brachial vein showed a crossover of microcavitations along the entire length of the aneurysm into the left atrium. The pulmonary veins drained normally into the left atrium. Exercise Stress Testing During a treadmill test in which a modified Bruce protocol was used, the patient experienced palpitations, chest pain, and shortness of breath. Her heart rate was 90 B/min in the resting phase, 110 B/min in an upright resting position, and 135 B/min at 1 minute of mild exercise (0% elevation, 2.5 MPH). She was unable to
124
Angelini et al. TABLE 1. Pressures and Oxygen Saturation in the Cardlac Cavltles. Hemodynamic data 0 2
Site RA
svc IVC RV MPA LV A0 LA
Pressures (mm He3
saturation
a = 9,v = 9,m = 7 a = 9,v = 9,m = I a = 9.v = 9.m = 7 261 1-7 26/10, fl 180/0-12 180/100, 3 3 a = 12, v = 10, m = 7
77 74 79 81 80 94 94 94
Follow-Up
At 6-month follow-up, the patient’s condition was normalized. She had returned to work, and she reported relief of all preoperative cardiovascular symptoms.
(%)
“AO. aorta; IVC, inferior vena cava; LA, left
atrium; LV, left ventricle; MPA. main pulmonary artery; RA, right atrium; RV, right ventricle: SVC. superior vena cava.
increase her heart rate during the next 4 minutes and stopped exercising with a maximal blood pressure of 110/80 mm Hg (1 10/80 mm Hg at rest) and nonspecific ST-T changes. Oxygen capillary saturation was monitored throughout the test by an electronic digital sensor and remained normal (98-99%). Cardiac Catheterization
Pressures and oxygen saturations were obtained during a right and left heart catheterization (Table I). The right heart catheter could be passed from different points of the atrial septum into the left atrium, the right and left pulmonary veins, and the left ventricle. Angiography confirmed the presence of a small atrial septal defect with a calculated left-to-right shunt of 1.4: 1 .O. Pulmonary venous drainage was normal. Right pulmonary artery and vein angiographic studies revealed evidence of a large ASA prolapsing into the right atrium. Even with few hemodynamic signs of severe cardiac decompensation, we believed that this patient’s symptoms were primarily organic and were due to right ventricular inlet obstruction by the prolapsing septal aneurysm. Therefore, surgical repair was recommended. Surgical/PathologicaI Findings
At surgery, a large (4.0 X 5.0 cm) fossa ovalis aneurysm was found, bulging into the right atrium. The aneurysm was replete with fenestrations. Microscopy of the atrial septal tissue showed myxoid degeneration with increased interstitial collagen. No other defect was noted at surgery. The ASA was resected, the atrial septum was repaired by patch, and there were no postoperative complications. The patient was discharged on the 8th postoperative day, with no residual extra heart sounds or murmurs.
DISCUSSION
This unusual case illustrates a pathological entity that has not been previously described, namely, right atrial obstruction from a protruding large ASA in an otherwise normal heart. Differential diagnosis for any case involving symptoms similar to those found in this case should include other right atrial lesions such as right atrial myxoma and other tumors of the heart, cor triatriatum dexter, and right atrial clots. ASA is diagnosed essentially by echocardiography , even though with angiography a fairly high degree of assurance can be reached. Precise images of the aneurysm can be obtained by two-dimensional echocardiography, in different projections, by both the transthoracic and the transesophageal routes. Contrast echocardiography can enhance the imaging, and a Valsalva maneuver can frequently demonstrate the prolapse of the ASA from the right to the left atrium [4].Magnetic resonance imaging has also recently been shown to be quite demonstrative [ 5 ] . ASA appears to stem from two factors, each with varying importance depending on the case: 1) the thickness, stiffness, or compliance of the fossa ovalis; and 2) the pressure gradient between the atrial cavities. In cases of very thin, compliant fossa ovalis tissue, the normally higher pressure in the left atrium would cause the fossa ovalis to prolapse into the right atrium. In cases with a marked increase in atrial pressure (as in tricuspid atresia with obstructive atrial septal defect), a minor increase in the fossa ovalis compliance would cause it to prolapse. The histologic findings in our case suggest that myxoid degeneration of the fossa ovalis tissue could be an important condition predisposing to ASA and explaining its association with mitral valve prolapse [31]. Abnormal physical findings associated with ASA have been described in the literature, but not substantiated. In particular, the presence of systolic click [8] has been frequently reported; in some patients, however, it may be caused by mitral valve prolapse rather than by ASA alone. In our case, the systolic click disappeared after surgical correction of ASA. Since this patient did not have mitral valve prolapse, a direct relationship between the click and ASA is suggested. Heretofore, in addition to atrial arrhythmias [3,12,33], the clinical manifestations of ASA have been mainly related to the possibility [ 12,15,16,23,37] of systemic and pulmonary embolism. The unusual wide motion of
Aneurysm of the Atrial Septum
the atrial septum during respiration [37] and the Valsalva maneuver [38] could explain the mechanism of embolization of any thrombotic material that might attach itself to the ASA wall 1371. Our case report illustrates the possibility that ASA alone, particularly when it is large, can create serious functional disabilities, mainly by obstructing the right ventricular inlet during exercise. The difficulty in objectively showing the importance of this mechanism is related to the absence of definite hemodynamic or Doppler signs of obstruction at rest. The absence of a significant resting gradient is probably justified by both the low pressure regimen in the right atrium (tricuspid stenosis or atrial myxoma of clinical importance may also cause relatively mild gradients) and the peculiar situation of this right atrial mass, caudal to the superior vena cava but cranial to the inferior vena cava flow. Exercise testing with Doppler echocardiography could have been more revealing and should be done in future similar cases. Easy fatiguability and dyspnea were most probably related to this pathophysiological change in our patient. Another mechanism of functional limitation, suggested by our case, is the nonspecific cardiac tumor effect. Indeed, a mass moving inside the heart tends to be perceived by the patient as chest pressure, pain, or palpitations: a vague sense of abnormal heart function. It is interesting to note that our patient had had several consultations from different physicians and that the majority favored the diagnosis of cardiac neurosis or neurasthenia. However, she was cured by resection of the ASA . ACKNOWLEDGMENTS
The authors thank Rebecca Teaff, Section of Scientific Publications, Texas Heart Institute, for editorial assistance with this article. REFERENCES Freedom R, Rowe R: Aneurysm of the atrial septum in tricuspid atresia: diagnosis during life and therapy. Am J Cardiol 32:265, 1976. Sahn DJ: Allen HD, Anderson R, Goldberg SJ: Echocardiographic diagnosis of atrial septal aneurysm in an infant with hypoplastic right heart syndrome. Chest 73:227, 1978. Wolf WJ, Casta A, Sapire DW: Atrial septal aneurysms in infants and children. Am Heart J 113:1149, 1987. Reder RF, Yeh HC, Steinfeld L: Aneurysm of the interatrial septum causing pulmonary venous obstruction in an infant with tricuspid atresia. Am Heart J 102:786, 1981. Topaz 0, Feigl A, Edwards JE: Aneurysm of the fossa ovalis in infants: a pathologic study. Pediatr Cardiol 6:65-68, 1985. 6. Casta A, Casta DI Sapire-DW, Swischuk L: True congenital aneurysm of the septum primum not associated with obstructive right or left-sided lesions, identified by two-dimensional echocar-
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