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Unusual phrenic arteriovenousmalformation mimicking pulmonary sequestration with heart failure: Two cases successfully treated by surgery
February 1990
410
Brief Communications
volving the most distal portion of the ascending aorta and the most proximal portion of the aortic arch and innominate artery was seen (Fig. 2, right panel). The left ventricular function and coronary arteries were normal. At surgery, a large ruptured aortic saccular aneurysm surrounded by thrombus in the anterior mediastinum was discovered (Fig. 2, left panel). The aneurysm was resected and the involved portion of the aorta and innominate artery were replaced with a Dacron synthetic graft. The patient tolerated the procedure and within several days was afebrile, alert, and was responding appropriately. Atypical presentations of a dissecting aneurysm in the aorta have been previously reported by Murray et al., 2 in which fever was the initial manifestation associated with dissecting aneurysm in four patients with prolonged illness. Because of fever and a murmur of aortic regurgitation, aortic dissection was initially treated as bacterial endocarditis in two patients. Our patient differs in that the acute presentation of fever, confusion, and mediastinal mass without a murmur of aortic insufficiency was not initially suspected as aortic aneurysm. Additional initial diagnostic testing such as CT scanning without contrast and echocardiography failed to identify the unusual location of this leaking, ruptured thoracic aneurysm. The differential diagnosis of a mediastinal mass with fever, hypoxemia, and pleural effusion must include tumor and/or pneumonia. A pleuracentesis must be performed. However, because of his failure to improve and follow-up CT studies demonstrating the mediastinal mass to be of mixed density, a thoracic aortic aneurysm was advanced as a correctable etiology for problems in this patient. Aortography demonstrated the location of a ruptured, saccular aortic aneurysm with exudation of blood into the pleural space, producing a febrile illness. Diagnostic techniques to identify aortic dissections and aneurysms have improved in the past two decades, with contrast-enhanced CT scanning being highly specific and sensitive for aortic aneurysms in most locations. 3, 4 Transthoracic cardiac echocardiography has also been found to be of value in the diagnosis of aortic aneurysm, although several locations such as the descending aorta can not be visualized adequately. Most recently, transesophageal echocardiography for the diagnosis of aortic dissection has been demonstrated to be highly efficient and very accurate. 5 However, as with transthoracic echocardiography, certain locations such as the high ascending aorta and arch may not be visualized by the transesophageal technique. Correctable lesions in the anterior mediastinum must be identified early in the evaluation of patients with abnormal chest x-ray findings. When CT scan or echocardiography suggest such lesions, the early use of aortography for aortic aneurysms, as demonstrated by this patient, provides rapid identification and leads to early and potentially life-saving treatment of a patient with a lethal but correctable illness, 6 REFERENCES
1. Roberts WC. Aortic dissection: anatomy, consequences, and causes. AM HEARTJ 1981;101:195-214.
American Heart Journal
2. Murray HW, Mann JJ, Genecin A, McKusick VA. Fever with dissecting aneurysm of the aorta. Am J Med 1976;61:140-4. 3. Axelbaum SP, Schellinger D, Gomes MN, et al. Computed tomographic evaluation of aortic aneurysms. AJR 1976;127: 75-8. 4. GodwinJD, Herfkens RL, Skioldebranch CG, et al. Evaluation of dissections and aneurysms of the thoracic aorta by conventional and dynamic CT scanning. Radiology 1980;136:125-33. 5. Mohr-Kahaly S, Erbel R, Steller D, Borner N, Drexler M, Meyer J. Aortic dissection detected by transesophageal echocardiography. Int J Card Imaging 1986;2:31-5. 6. DeSanctis RW, Doroghazi RM, Austen WG, Buckley MJ. Aortic dissection. N Engl J Med 1987;317:1060-7.
Unusual phrenic arteriovenous malformation mimicking pulmonary sequestration with heart failure: Two cases successfully treated by surgery Mei-Hwan Wu, MD, Hung-Chi Lue, MD, and Chi-Ren Hong, MD. a Taipei, Taiwan, Republic of China
The well-known locations of arteriovenous malformation (AVM) sometimes complicate the clinical picture and interfere with the correct diagnosis. 1-3 Recently, we encountered two cases of AVM with unusual anatomic locations mimicking pulmonary sequestration. Correct diagnosis was reached with the help of the newly-developed color Doppler echocardiography, One patient underwent total excision of the AVM and the other was managed by ligation of the feeding arteries and draining veins. The surgical implications are discussed. Case No. 1. A male infant was noted to have tachypnea and a problem with prolonged feeding soon after birth. He was referred to this hospital at the age of 2 months. Marked respiratory distress with diffuse moist rales and a grade II/VI systolic murmur at the left mid sternal border were noted. The liver was palpable 7 cm below the right costal margin. The femoral pulse was bounding to palpation. The chest films revealed marked cardiomegaly with increased pulmonary vascularity. Enlarged right atrium (RA) and right ventricle (RV) with paradoxical septal motion were noted in echocardiographic examination. Color Doppler demonstrated an unusual mosaic color flow draining into the right inferior part of the RA (Fig. 1). The spectral display disclosed a continuous turbulence with a pressure gradient of 10 mm Hg. Cardiac catheterization and angiography revealed an AVM with a dilated tortuous artery arising from the right inferior phrenic artery that pierced
From the Departments of Pediatrics and Surgery,a National TaiwanUniversity, and National Taiwan UniversityHospital. Reprint requests: Mei-HwanWu, MD,Department ofPediatrics, National Taiwan UniversityHospital, No. 1 Chang-TehSt., Taipei, Taiwan, 10016, Republic of China 4/4/17234
Volume 119 NumbeL" 2, Part I
Brief ~'---uommumcatmns
4 11
Fig. 1. Color Doppler echocardiogram, subcostal long-axis view. Sagittal section to the right of the right atrium shows the right part of the right atrium and reveals an abnormal mosaic turbulence (arrow) in the righ t atrium. A, Anterior; I: inferior; Liv, liver; P, posterior; RA, right atrium; S, superior.
the diaphragm and fed parts of the middle and lower lobes of the right lung. A large venous phase vessel was found draining into the RA at the junction of the RA and inferior vena cava. There was a 30% increase of 02 saturation in the RA. Palliative ligation of the inferior phrenic artery was done initially because of his intractable heart failure and poor general condition. The patient's condition improved, but heart failure recurred 2 weeks later. A second cardiac catheterization at the age of 4 months revealed opacification of the same AVM via collaterals from the pancreatic arching and a persistent 19 % increase of 02 saturation in the RA. Surgical excision of the AVM together with parts of the right middle and lower lobes of the involved lung was then performed. The AVM was found overlying the pulmonary parenchyma, with a part of it penetrating into the pleura, occupying the perihilar area with many macro- and microarteriovenous fistulas. No communications between the AVM and the pulmonary arterial or venous system could be found. The postoperative course was complicated by three episodes of respiratory distress, but the patient was eventually weaned from the respirator. He did .well thereafter with no evidence of recurrence during the 2-1/2 years of follow-up. Case 2. A full-term female infant developed feeding difficulties with shortness of breath, profuse sweating, and failure to thrive at the age of 2 months. She was brought to this hospital at the age of 4 months. Chest films showed mesoposition of the heart with marked cardiomegaly and increased pulmonary vascularity. Echocardiographic examination showed an interruption of the interatrial septum
with an enlarged RA and RV. Cardiac catheterization revealed a 23 % increase of 02 saturation in the RA. Angiography disclosed, as in case No. 1, a tortuous engorged artery from the right inferior phrenic artery, piercing the diaphragm in three branches and opacifying the right lower lung field (Fig. 2). Two engorged veins drained the AVM, returning to the junction of the RA and inferior vena cava. Surgical ligation of the three feeding arteries and the two draining veins was performed successfully I week after the cardiac catheterization. Operative findings confirmed the angiographic diagnosis, which was very similar to that of case No. 1. The postoperative course was uneventful. The baby improved and has done well until this writing, 17 months after surgery. The interatrial left-to-right shunt disappeared 6 months following surgery. The anatomic distributions of the AVM in these two cases are similar to pulmonary sequestration in terms of their location and the pattern of the feeding arteries. 4 However, the absence of abnormal lung tissue in the resected specimen, together with a normal right pulmonary vasculature and bronchial tree, excluded the diagnosis of pulmonary sequestration. The only report of a similar case concerned a 4-year-old asymptomatic boy with AVM from the left phrenic artery to the left innominate vein. 1 While sonographic examination of such AVM might delineate the feeding arteries, 5 the unusual vascular pattern--especially the draining sites--can be readily documented by the newly developed color Doppler as unusual continuous turbulence. Embolotherapy of the feeding arteries is now recommended as a palliative or adjuvant therapy preceding the
412
February 1990 American Heart Journal
Brief Communications
3. 4. 5. 6.
malformation in infants less than 6 months of age. Pediatrics 1979;64:238-41. Atwood GF, King TD, Graham TP Jr, Canent RV Jr, Ebert PA, Spach MS. Thoracic arteriorvenous fistula. Am J Dis Child 1975;129:233-6. Choplin RH, Siegel MJ. Pulmonary sequestration: six unusual presentations. AJR 1980;134:695-700. Kangarloo H, Gold RH, Benson L, Diament MJ, DiSessa T, Boechat MT. Sonography of extrathoracic left-to-right shunt in infants and children. AJR 1983;141:923-6. White RI Jr. Embolotherapy in vascular disease. AJR 1984;142:27-30.
Atrial alternans J. T i m o t h y Bricker, MD, and Daniel J. M u r p h y Jr, MD.
Houston, Texas
Fig. 2. A and B, Aortography (A, posteroanterior view; B, left lateral view) shows an engorged inferior phrenic artery (arrow), with bifurcations piercing the diaphragm, arborized in the right lower p a r t of the lung. C, Venous phase of the aortography (posteroanterior view) shows two draining veins (arrowheads) joined together, then entering the junction of the right a t r i u m and inferior vena cava. T h e right atrium and inferior vena cava were then also opacifled. D, Levophase of the pulmonary angiography revealing a left a t r i u m - t o - r i g h t atrium shunt (arrowheads). A, Anterior; Ao, aorta;/, inferior; IVC, inferior vena cava; LA, left atrium; P, posterior; R, right; RA, right atrium; S, superior.
total removal of the AVM. 6 Ligation of the feeding artery is not recommended due to the early recurrence and the obliteration of the route of future embolotherapy. 6 Total removal of the malformation is a more definite procedure, b u t it m a y be difficult in cases with diffuse lesions or lesions near the vital organs. Ligation of the feeding artery was tried in one of our patients, b u t early recurrence developed a n d m a n d a t e d the t o t a l removal. However, ligation of the feeding arteries and also the draining veins in the second case was successful, as the 11/2 years of follow-up testify. T h e clinical significance of such a procedure is still unknown. Accumulated experience with more cases with longer periods of follow-up is necessary. REFERENCES
1. Gray JR, Williams HP. Arteriovenous aneurysm of phrenic vessels simulating cardiac fistula. Circulation 1962;26:432-8. 2. Knudson MRP, Alden LCER. Symptomatic arteriovenous
The pathophysiology of pulsus alternans has been a source of debate. Beat-to-beat alternation of right atrial to left atrial flow across a p a t e n t foramen ovale was observed in a baby who h a d obstruction of ventricular inflow due to cardiac tumors and had arterial pulsus alternans identified by Doppler echocardiography. This suggests t h a t atrial contractility m a y be a factor in some cases of pulsus alternans. A 3.1 kg t e r m newborn female product of an uneventful pregnancy, labor, and delivery was noted to be cyanotic and to have low cardiac output. Echocardiographic examination revealed numerous cardiac tumors. The right ventricular inflow was obstructed by a large (approximately 2 cm in diameter) tumor t h a t a p p e a r e d to be attached to the midportion of the interventricular septum and perhaps involved the tricuspid valve. Two other large t u m o r s (one right ventricular and one left ventricular) were found as well as numerous small tumors throughout the myocardium of both ventricles, which did not obstruct blood flow. Pulmonary blood flow was by way of the ductus arteriosus. There was right-to-left flow at the foramen ovale with beat-to-beat alternations of large and small amounts of flow, as assessed by Doppler echocardiography (Fig. 1). Pulsus alternans of aortic flow was also observed (Fig. 2). There was no tricuspid regurgitation and there was minimal antegrade flow across the pulmonary valve, with continuous flow in the pulmonary artery due to the ductus arteriosus. Venous filling of the right atrium d e m o n s t r a t e d t h a t flow in the vena cava had respiratory variation, b u t there was no beat-to-beat alternating flow pattern. Balloon From the LillieFrank AbercrombieSectionof Cardiology,Texas Children's Hospital and Department of Pediatrics, Baylor Collegeof Medicine. Supported in part by CRC Grant RR-00188 from the General Clinic ResearchBranch of the NationalInstitutes of Health and by NIH No. 1 K07 HL01940-01 (Preventive CardiologyAcademicAward). Reprint requests: J. Timothy Bricker, MD, Section of Cardiology,Texas Children's Hospital, 6621 Fannin Ave., Houston, TX 77030. 4/4/17528
410
Brief Communications
volving the most distal portion of the ascending aorta and the most proximal portion of the aortic arch and innominate artery was seen (Fig. 2, right panel). The left ventricular function and coronary arteries were normal. At surgery, a large ruptured aortic saccular aneurysm surrounded by thrombus in the anterior mediastinum was discovered (Fig. 2, left panel). The aneurysm was resected and the involved portion of the aorta and innominate artery were replaced with a Dacron synthetic graft. The patient tolerated the procedure and within several days was afebrile, alert, and was responding appropriately. Atypical presentations of a dissecting aneurysm in the aorta have been previously reported by Murray et al., 2 in which fever was the initial manifestation associated with dissecting aneurysm in four patients with prolonged illness. Because of fever and a murmur of aortic regurgitation, aortic dissection was initially treated as bacterial endocarditis in two patients. Our patient differs in that the acute presentation of fever, confusion, and mediastinal mass without a murmur of aortic insufficiency was not initially suspected as aortic aneurysm. Additional initial diagnostic testing such as CT scanning without contrast and echocardiography failed to identify the unusual location of this leaking, ruptured thoracic aneurysm. The differential diagnosis of a mediastinal mass with fever, hypoxemia, and pleural effusion must include tumor and/or pneumonia. A pleuracentesis must be performed. However, because of his failure to improve and follow-up CT studies demonstrating the mediastinal mass to be of mixed density, a thoracic aortic aneurysm was advanced as a correctable etiology for problems in this patient. Aortography demonstrated the location of a ruptured, saccular aortic aneurysm with exudation of blood into the pleural space, producing a febrile illness. Diagnostic techniques to identify aortic dissections and aneurysms have improved in the past two decades, with contrast-enhanced CT scanning being highly specific and sensitive for aortic aneurysms in most locations. 3, 4 Transthoracic cardiac echocardiography has also been found to be of value in the diagnosis of aortic aneurysm, although several locations such as the descending aorta can not be visualized adequately. Most recently, transesophageal echocardiography for the diagnosis of aortic dissection has been demonstrated to be highly efficient and very accurate. 5 However, as with transthoracic echocardiography, certain locations such as the high ascending aorta and arch may not be visualized by the transesophageal technique. Correctable lesions in the anterior mediastinum must be identified early in the evaluation of patients with abnormal chest x-ray findings. When CT scan or echocardiography suggest such lesions, the early use of aortography for aortic aneurysms, as demonstrated by this patient, provides rapid identification and leads to early and potentially life-saving treatment of a patient with a lethal but correctable illness, 6 REFERENCES
1. Roberts WC. Aortic dissection: anatomy, consequences, and causes. AM HEARTJ 1981;101:195-214.
American Heart Journal
2. Murray HW, Mann JJ, Genecin A, McKusick VA. Fever with dissecting aneurysm of the aorta. Am J Med 1976;61:140-4. 3. Axelbaum SP, Schellinger D, Gomes MN, et al. Computed tomographic evaluation of aortic aneurysms. AJR 1976;127: 75-8. 4. GodwinJD, Herfkens RL, Skioldebranch CG, et al. Evaluation of dissections and aneurysms of the thoracic aorta by conventional and dynamic CT scanning. Radiology 1980;136:125-33. 5. Mohr-Kahaly S, Erbel R, Steller D, Borner N, Drexler M, Meyer J. Aortic dissection detected by transesophageal echocardiography. Int J Card Imaging 1986;2:31-5. 6. DeSanctis RW, Doroghazi RM, Austen WG, Buckley MJ. Aortic dissection. N Engl J Med 1987;317:1060-7.
Unusual phrenic arteriovenous malformation mimicking pulmonary sequestration with heart failure: Two cases successfully treated by surgery Mei-Hwan Wu, MD, Hung-Chi Lue, MD, and Chi-Ren Hong, MD. a Taipei, Taiwan, Republic of China
The well-known locations of arteriovenous malformation (AVM) sometimes complicate the clinical picture and interfere with the correct diagnosis. 1-3 Recently, we encountered two cases of AVM with unusual anatomic locations mimicking pulmonary sequestration. Correct diagnosis was reached with the help of the newly-developed color Doppler echocardiography, One patient underwent total excision of the AVM and the other was managed by ligation of the feeding arteries and draining veins. The surgical implications are discussed. Case No. 1. A male infant was noted to have tachypnea and a problem with prolonged feeding soon after birth. He was referred to this hospital at the age of 2 months. Marked respiratory distress with diffuse moist rales and a grade II/VI systolic murmur at the left mid sternal border were noted. The liver was palpable 7 cm below the right costal margin. The femoral pulse was bounding to palpation. The chest films revealed marked cardiomegaly with increased pulmonary vascularity. Enlarged right atrium (RA) and right ventricle (RV) with paradoxical septal motion were noted in echocardiographic examination. Color Doppler demonstrated an unusual mosaic color flow draining into the right inferior part of the RA (Fig. 1). The spectral display disclosed a continuous turbulence with a pressure gradient of 10 mm Hg. Cardiac catheterization and angiography revealed an AVM with a dilated tortuous artery arising from the right inferior phrenic artery that pierced
From the Departments of Pediatrics and Surgery,a National TaiwanUniversity, and National Taiwan UniversityHospital. Reprint requests: Mei-HwanWu, MD,Department ofPediatrics, National Taiwan UniversityHospital, No. 1 Chang-TehSt., Taipei, Taiwan, 10016, Republic of China 4/4/17234
Volume 119 NumbeL" 2, Part I
Brief ~'---uommumcatmns
4 11
Fig. 1. Color Doppler echocardiogram, subcostal long-axis view. Sagittal section to the right of the right atrium shows the right part of the right atrium and reveals an abnormal mosaic turbulence (arrow) in the righ t atrium. A, Anterior; I: inferior; Liv, liver; P, posterior; RA, right atrium; S, superior.
the diaphragm and fed parts of the middle and lower lobes of the right lung. A large venous phase vessel was found draining into the RA at the junction of the RA and inferior vena cava. There was a 30% increase of 02 saturation in the RA. Palliative ligation of the inferior phrenic artery was done initially because of his intractable heart failure and poor general condition. The patient's condition improved, but heart failure recurred 2 weeks later. A second cardiac catheterization at the age of 4 months revealed opacification of the same AVM via collaterals from the pancreatic arching and a persistent 19 % increase of 02 saturation in the RA. Surgical excision of the AVM together with parts of the right middle and lower lobes of the involved lung was then performed. The AVM was found overlying the pulmonary parenchyma, with a part of it penetrating into the pleura, occupying the perihilar area with many macro- and microarteriovenous fistulas. No communications between the AVM and the pulmonary arterial or venous system could be found. The postoperative course was complicated by three episodes of respiratory distress, but the patient was eventually weaned from the respirator. He did .well thereafter with no evidence of recurrence during the 2-1/2 years of follow-up. Case 2. A full-term female infant developed feeding difficulties with shortness of breath, profuse sweating, and failure to thrive at the age of 2 months. She was brought to this hospital at the age of 4 months. Chest films showed mesoposition of the heart with marked cardiomegaly and increased pulmonary vascularity. Echocardiographic examination showed an interruption of the interatrial septum
with an enlarged RA and RV. Cardiac catheterization revealed a 23 % increase of 02 saturation in the RA. Angiography disclosed, as in case No. 1, a tortuous engorged artery from the right inferior phrenic artery, piercing the diaphragm in three branches and opacifying the right lower lung field (Fig. 2). Two engorged veins drained the AVM, returning to the junction of the RA and inferior vena cava. Surgical ligation of the three feeding arteries and the two draining veins was performed successfully I week after the cardiac catheterization. Operative findings confirmed the angiographic diagnosis, which was very similar to that of case No. 1. The postoperative course was uneventful. The baby improved and has done well until this writing, 17 months after surgery. The interatrial left-to-right shunt disappeared 6 months following surgery. The anatomic distributions of the AVM in these two cases are similar to pulmonary sequestration in terms of their location and the pattern of the feeding arteries. 4 However, the absence of abnormal lung tissue in the resected specimen, together with a normal right pulmonary vasculature and bronchial tree, excluded the diagnosis of pulmonary sequestration. The only report of a similar case concerned a 4-year-old asymptomatic boy with AVM from the left phrenic artery to the left innominate vein. 1 While sonographic examination of such AVM might delineate the feeding arteries, 5 the unusual vascular pattern--especially the draining sites--can be readily documented by the newly developed color Doppler as unusual continuous turbulence. Embolotherapy of the feeding arteries is now recommended as a palliative or adjuvant therapy preceding the
412
February 1990 American Heart Journal
Brief Communications
3. 4. 5. 6.
malformation in infants less than 6 months of age. Pediatrics 1979;64:238-41. Atwood GF, King TD, Graham TP Jr, Canent RV Jr, Ebert PA, Spach MS. Thoracic arteriorvenous fistula. Am J Dis Child 1975;129:233-6. Choplin RH, Siegel MJ. Pulmonary sequestration: six unusual presentations. AJR 1980;134:695-700. Kangarloo H, Gold RH, Benson L, Diament MJ, DiSessa T, Boechat MT. Sonography of extrathoracic left-to-right shunt in infants and children. AJR 1983;141:923-6. White RI Jr. Embolotherapy in vascular disease. AJR 1984;142:27-30.
Atrial alternans J. T i m o t h y Bricker, MD, and Daniel J. M u r p h y Jr, MD.
Houston, Texas
Fig. 2. A and B, Aortography (A, posteroanterior view; B, left lateral view) shows an engorged inferior phrenic artery (arrow), with bifurcations piercing the diaphragm, arborized in the right lower p a r t of the lung. C, Venous phase of the aortography (posteroanterior view) shows two draining veins (arrowheads) joined together, then entering the junction of the right a t r i u m and inferior vena cava. T h e right atrium and inferior vena cava were then also opacifled. D, Levophase of the pulmonary angiography revealing a left a t r i u m - t o - r i g h t atrium shunt (arrowheads). A, Anterior; Ao, aorta;/, inferior; IVC, inferior vena cava; LA, left atrium; P, posterior; R, right; RA, right atrium; S, superior.
total removal of the AVM. 6 Ligation of the feeding artery is not recommended due to the early recurrence and the obliteration of the route of future embolotherapy. 6 Total removal of the malformation is a more definite procedure, b u t it m a y be difficult in cases with diffuse lesions or lesions near the vital organs. Ligation of the feeding artery was tried in one of our patients, b u t early recurrence developed a n d m a n d a t e d the t o t a l removal. However, ligation of the feeding arteries and also the draining veins in the second case was successful, as the 11/2 years of follow-up testify. T h e clinical significance of such a procedure is still unknown. Accumulated experience with more cases with longer periods of follow-up is necessary. REFERENCES
1. Gray JR, Williams HP. Arteriovenous aneurysm of phrenic vessels simulating cardiac fistula. Circulation 1962;26:432-8. 2. Knudson MRP, Alden LCER. Symptomatic arteriovenous
The pathophysiology of pulsus alternans has been a source of debate. Beat-to-beat alternation of right atrial to left atrial flow across a p a t e n t foramen ovale was observed in a baby who h a d obstruction of ventricular inflow due to cardiac tumors and had arterial pulsus alternans identified by Doppler echocardiography. This suggests t h a t atrial contractility m a y be a factor in some cases of pulsus alternans. A 3.1 kg t e r m newborn female product of an uneventful pregnancy, labor, and delivery was noted to be cyanotic and to have low cardiac output. Echocardiographic examination revealed numerous cardiac tumors. The right ventricular inflow was obstructed by a large (approximately 2 cm in diameter) tumor t h a t a p p e a r e d to be attached to the midportion of the interventricular septum and perhaps involved the tricuspid valve. Two other large t u m o r s (one right ventricular and one left ventricular) were found as well as numerous small tumors throughout the myocardium of both ventricles, which did not obstruct blood flow. Pulmonary blood flow was by way of the ductus arteriosus. There was right-to-left flow at the foramen ovale with beat-to-beat alternations of large and small amounts of flow, as assessed by Doppler echocardiography (Fig. 1). Pulsus alternans of aortic flow was also observed (Fig. 2). There was no tricuspid regurgitation and there was minimal antegrade flow across the pulmonary valve, with continuous flow in the pulmonary artery due to the ductus arteriosus. Venous filling of the right atrium d e m o n s t r a t e d t h a t flow in the vena cava had respiratory variation, b u t there was no beat-to-beat alternating flow pattern. Balloon From the LillieFrank AbercrombieSectionof Cardiology,Texas Children's Hospital and Department of Pediatrics, Baylor Collegeof Medicine. Supported in part by CRC Grant RR-00188 from the General Clinic ResearchBranch of the NationalInstitutes of Health and by NIH No. 1 K07 HL01940-01 (Preventive CardiologyAcademicAward). Reprint requests: J. Timothy Bricker, MD, Section of Cardiology,Texas Children's Hospital, 6621 Fannin Ave., Houston, TX 77030. 4/4/17528