Right Pulmonary Artery Obstruction After Pulmonarv Arterv Bandingv J
J
Murray A. Robertson, MD, PhD, Patricia A. Penkoske, MD, and Neil F. Duncan, MD Divisions of Pediatric Cardiology and Pediatric Cardiothoracic Surgery, University of Alberta Hospital, Edmonton, Alberta, Canada
Serial assessment of pulmonary artery flow by Doppler echocardiography was carried out in 15 infants after pulmonary artery banding. Three infants were identified as having branch pulmonary artery obstruction based on diastolic pulmonary artery flow. It is concluded that this flow profile may be specific for branch pulmonary artery obstruction after pulmonary artery banding. (Ann Thorac Surg 1991;51:73-5)
P
ulmonary artery banding is an effective palliative surgical procedure in infants with congenital heart defects associated with increased pulmonary blood flow [I, 21. The rationale is to protect the pulmonary vasculature from irreversible obstructive pulmonary arteriopathy until such time as definitive surgical correction of the underlying cardiac lesion can be undertaken with minimal operative risk. Although a relatively simple surgical procedure, it is not without serious morbidity. Insufficient restriction of pulmonary blood flow by too loose an application of the pulmonary artery band may result in inadequate protection of the distal pulmonary vasculature. Migration or erosion of the banding material resulting in partial or complete obstruction of a branch pulmonary artery is well described [3, 41 and may seriously complicate ultimate surgical correction of the cardiac defect, potentially increasing the operative mortality and morbidity. Detection of branch pulmonary obstruction is often difficult by standard noninvasive imaging techniques. We report here Doppler echocardiographic diagnosis of proximal branch pulmonary artery obstruction after pulmonary artery banding.
Material and Methods Fifteen infants aged 2 weeks to 8 months (mean age, 7 weeks) with cardiac lesions resulting in excessive pulmonary blood flow underwent pulmonary artery banding palliation according to previously published techniques [l]. Doppler echocardiographic interrogation of the pulmonary artery band gradient was initially carried odt within 48 hours of operation and then 24 to 48 hours before hospital discharge in all infants. In addition, all infants had regular measurements of pulmonary band pressure gradients after discharge. Accepted for publication Aug 31, 1990. Address reprint requests to Dr Robertson, Division of Pediatric Cardiology, Room 2C3.84, Walter C. MacKenzie Health Sciences Centre, Edmonton, Alberta, Canada T6G-207.
0 1991 by
The Society of,ThoracicSurgeons
The m,aximum pulmonary band pressure gradients were obtained using color flow-directed continuous-wave Doppler (Toshiba SSH-65A) measurements from standard subcostal and parasternal orientations. Color M-mode assessment of the proximal branch pulmonary arteries was obtained from a suprasternal or high parasternal approach.
Results All infants had adequate Doppler pulmonary artery band pressure gradients with a mean gradient of 72 11 mm Hg at the time of hospital discharge. Three of the 15 infants demonstrated continuous flow in the proximal right pulmonary artery both on color M-mode (Fig 1)and continuous-wave Doppler echocardiography (Fig 2). These flow patterns were first detected at 2 weeks, 8 weeks, and 3 months after pulmonary artery banding. Branch pulmonary artery narrowing was not identified by two-dimensional real-time imaging. Eight infants subsequently underwent cardiac catheterization. All 3 infants with Doppler-detected diastolic pulmonary artery flow demonstrated proximal right pulmonary artery obstruction by the banding material on angiography. None of the other infants had angiographic or echocardiographic evidence of branch pulmonary artery obstruction. There was no difference in the systolic pulmonary artery band gradients between those with (68 ? 5 mm Hg) and those without (74 ? 12 mm Hg) branch pulmonary artery obstruction. Figure 3 shows pulmonary angiography before and after pulmonary artery banding in an infant with diastolic right pulmonary artery flow first detected 3 months postoperatively. Stenosis of the right pulmonary artery by the banding material is evident. On serial postoperative chest radiographs none of these infants had obvious evidence of branch pulmonary artery obstruction. One infant died after operation consisting of closure of a ventricular septa1 defect, removal of the pulmonary artery band, and reconstruction of the right pulmonary artery. A second child died after cardiac catheterization, having been seen initially with sudden onset of marked cyanosis. Both pulmonary angiography and autopsy findings confirmed severe narrowing of the origin of the right pulmonary artery with no obstruction of the left pulmonary artery. The other infant continues to do well 1 year after a corrective operation requiring reconstruction of the right pulmonary artery.
*
0003-4975/91/$3.50
74
Ann Thorac Surg
ROBERTSON ET AL POSTOPERATIVE PULMONARY ARTERY STENOSIS
1991;51:73-5
A
A
n
I
7 MPA
-
R
L I
\ B
MI MODE B Fig 1. (A) Suprasternal color M-mode echocardiography demonstrating diastolic right pulmonary artery flow (open arrows). Closed arrows indicate electrocardiographic R waves. (B)Schematic demonstrating orientation of color M-mode study shown in (A). (Ao = aorta; LPA = left pulmonary artery; MPA = main pulmonary artery; RPA = right pulmonary artery; SVC = superior vena cava.)
Comment Obstruction of a branch pulmonary artery after pulmonary artery banding is well described [3]. Failure to recognize this complication potentially increases the operative mortality of subsequent corrective operations as
Fig 2. (A) Continuous-wave Doppler recording showing peak systolic velocity of 4.2 mls (-70 mm Hg) across pulmonary artery band. Open arrows indicate diastolic flow in the right pulmonary artery. (B)Schematic demonstrating orientation of continuous-wave Doppler echocardiography in ( A ) across the pulmonary artery band (PAB) and proximal right pulmonary artery. (Ao = aorta; CW = continuous wave Doppler alignment; L = left pulmonary artery; MPA = main pulmonary artery; PV = pulmonary valve; R = right pulmonary artery; RVOT = right ventricular outflow tract.)
extensive reconstruction of the involved pulmonary arterial segment may be necessary. Standard chest radiographs may not be sufficiently sensitive to detect partial unilateral pulmonary flow obstruction as evident in the cases described here. The demonstration by Doppler echocardiography of diastolic flow in the proximal right pulmonary artery may be a specific sign of branch pulmonary artery obstruction. This flow pattern was observed only in infants with
Ann Thorac Surg 1991;51:7>5
ROBERTSON ET AL POSTOPERATIVE PULMONARY ARTERY STENOSIS
75
Fig 3. Frontal main pulmonary artery angiography before (pre) and after (post) pulmona y artery banding demonstrating postoperative stenosis of right pulmonary ortery (curved arrow).
angiographically confirmed branch pulmonary artery obstruction. The mechanism presumably is secondary to encroachment by the pulmonary artery band on the origin of the right pulmonary artery which, in comparison with the left pulmonary artery, arises more proximally and at a more acute angle from the main pulmonary artery. This results in a persistent gradient between the main and branch pulmonary artery, thereby accounting for the continuous Doppler flow profile observed. All of the branch pulmonary artery obstructions reported here involved the right pulmonary artery; however, the small number of patients involved does not permit any conclusions to be made as to the incidence of left pulmonary artery obstruction. Right pulmonary artery obstruction occurred in the presence of an adequate pressure gradient across the pulmonary artery band. The abnormal Doppler flow patterns were not seen in earlier postoperative studies, suggesting that branch pulmonary artery obstruction may be a progressive phenomenon. If recognized before progression to more severe forms of obstruction, it may be possible to intervene early to ultimately avoid more extensive pulmonary artery surgical reconstruction. However, this study does not address the issue of how severe branch pulmonary artery need be before abnormal diastolic flow becomes detectable by Doppler echocardiography. Low flow sensitivity of current color-flow systems may preclude earlier detection of low-velocity continuous diastolic flow associated
with postoperative branch pulmonary artery obstruction. Hence, a clinically significant degree of branch pulmonary artery obstruction may be necessary before detection by Doppler techniques. To avoid branch pulmonary artery obstruction, we now perform pulmonary artery banding using an anterior rather than a lateral thoracotomy, facilitating better visualization of the relationship of the banding material to the proximal right pulmonary artery. Our current approach is to study branch pulmonary flow by Doppler echocardiography early and serially after pulmonary artery banding. The recognition of a diastolic pulmonary artery flow pattern is an indication for pulmonary angiography and either revision of the pulmonary artery band or, when appropriate, early corrective operation.
References 1. Albus RA, Trusler GA, Izukawa T, Williams WG. Pulmonary
artery banding. J Thorac Cardiovasc Surg 1984;88:645-53. 2. Dooley KJ, Lucy PB, Fyler DC, Nadas AS. Results of pulmonary arterial banding in infancy. Survey of 5 years experience in the New England regional infant cardiac program. Am J Cardiol 1985;36:484-8. 3. Stark J. Pulmonary artery banding. In: Stark J, deLaval M, eds. Surgery for congenital heart defects. London: Grune & Stratton, 1983:187-95. 4. Danilowicz D, Prest S, Colvin S. The disappearing pulmonary artery band. Pediatr Cardiol 1990;11:47-9.
J
Murray A. Robertson, MD, PhD, Patricia A. Penkoske, MD, and Neil F. Duncan, MD Divisions of Pediatric Cardiology and Pediatric Cardiothoracic Surgery, University of Alberta Hospital, Edmonton, Alberta, Canada
Serial assessment of pulmonary artery flow by Doppler echocardiography was carried out in 15 infants after pulmonary artery banding. Three infants were identified as having branch pulmonary artery obstruction based on diastolic pulmonary artery flow. It is concluded that this flow profile may be specific for branch pulmonary artery obstruction after pulmonary artery banding. (Ann Thorac Surg 1991;51:73-5)
P
ulmonary artery banding is an effective palliative surgical procedure in infants with congenital heart defects associated with increased pulmonary blood flow [I, 21. The rationale is to protect the pulmonary vasculature from irreversible obstructive pulmonary arteriopathy until such time as definitive surgical correction of the underlying cardiac lesion can be undertaken with minimal operative risk. Although a relatively simple surgical procedure, it is not without serious morbidity. Insufficient restriction of pulmonary blood flow by too loose an application of the pulmonary artery band may result in inadequate protection of the distal pulmonary vasculature. Migration or erosion of the banding material resulting in partial or complete obstruction of a branch pulmonary artery is well described [3, 41 and may seriously complicate ultimate surgical correction of the cardiac defect, potentially increasing the operative mortality and morbidity. Detection of branch pulmonary obstruction is often difficult by standard noninvasive imaging techniques. We report here Doppler echocardiographic diagnosis of proximal branch pulmonary artery obstruction after pulmonary artery banding.
Material and Methods Fifteen infants aged 2 weeks to 8 months (mean age, 7 weeks) with cardiac lesions resulting in excessive pulmonary blood flow underwent pulmonary artery banding palliation according to previously published techniques [l]. Doppler echocardiographic interrogation of the pulmonary artery band gradient was initially carried odt within 48 hours of operation and then 24 to 48 hours before hospital discharge in all infants. In addition, all infants had regular measurements of pulmonary band pressure gradients after discharge. Accepted for publication Aug 31, 1990. Address reprint requests to Dr Robertson, Division of Pediatric Cardiology, Room 2C3.84, Walter C. MacKenzie Health Sciences Centre, Edmonton, Alberta, Canada T6G-207.
0 1991 by
The Society of,ThoracicSurgeons
The m,aximum pulmonary band pressure gradients were obtained using color flow-directed continuous-wave Doppler (Toshiba SSH-65A) measurements from standard subcostal and parasternal orientations. Color M-mode assessment of the proximal branch pulmonary arteries was obtained from a suprasternal or high parasternal approach.
Results All infants had adequate Doppler pulmonary artery band pressure gradients with a mean gradient of 72 11 mm Hg at the time of hospital discharge. Three of the 15 infants demonstrated continuous flow in the proximal right pulmonary artery both on color M-mode (Fig 1)and continuous-wave Doppler echocardiography (Fig 2). These flow patterns were first detected at 2 weeks, 8 weeks, and 3 months after pulmonary artery banding. Branch pulmonary artery narrowing was not identified by two-dimensional real-time imaging. Eight infants subsequently underwent cardiac catheterization. All 3 infants with Doppler-detected diastolic pulmonary artery flow demonstrated proximal right pulmonary artery obstruction by the banding material on angiography. None of the other infants had angiographic or echocardiographic evidence of branch pulmonary artery obstruction. There was no difference in the systolic pulmonary artery band gradients between those with (68 ? 5 mm Hg) and those without (74 ? 12 mm Hg) branch pulmonary artery obstruction. Figure 3 shows pulmonary angiography before and after pulmonary artery banding in an infant with diastolic right pulmonary artery flow first detected 3 months postoperatively. Stenosis of the right pulmonary artery by the banding material is evident. On serial postoperative chest radiographs none of these infants had obvious evidence of branch pulmonary artery obstruction. One infant died after operation consisting of closure of a ventricular septa1 defect, removal of the pulmonary artery band, and reconstruction of the right pulmonary artery. A second child died after cardiac catheterization, having been seen initially with sudden onset of marked cyanosis. Both pulmonary angiography and autopsy findings confirmed severe narrowing of the origin of the right pulmonary artery with no obstruction of the left pulmonary artery. The other infant continues to do well 1 year after a corrective operation requiring reconstruction of the right pulmonary artery.
*
0003-4975/91/$3.50
74
Ann Thorac Surg
ROBERTSON ET AL POSTOPERATIVE PULMONARY ARTERY STENOSIS
1991;51:73-5
A
A
n
I
7 MPA
-
R
L I
\ B
MI MODE B Fig 1. (A) Suprasternal color M-mode echocardiography demonstrating diastolic right pulmonary artery flow (open arrows). Closed arrows indicate electrocardiographic R waves. (B)Schematic demonstrating orientation of color M-mode study shown in (A). (Ao = aorta; LPA = left pulmonary artery; MPA = main pulmonary artery; RPA = right pulmonary artery; SVC = superior vena cava.)
Comment Obstruction of a branch pulmonary artery after pulmonary artery banding is well described [3]. Failure to recognize this complication potentially increases the operative mortality of subsequent corrective operations as
Fig 2. (A) Continuous-wave Doppler recording showing peak systolic velocity of 4.2 mls (-70 mm Hg) across pulmonary artery band. Open arrows indicate diastolic flow in the right pulmonary artery. (B)Schematic demonstrating orientation of continuous-wave Doppler echocardiography in ( A ) across the pulmonary artery band (PAB) and proximal right pulmonary artery. (Ao = aorta; CW = continuous wave Doppler alignment; L = left pulmonary artery; MPA = main pulmonary artery; PV = pulmonary valve; R = right pulmonary artery; RVOT = right ventricular outflow tract.)
extensive reconstruction of the involved pulmonary arterial segment may be necessary. Standard chest radiographs may not be sufficiently sensitive to detect partial unilateral pulmonary flow obstruction as evident in the cases described here. The demonstration by Doppler echocardiography of diastolic flow in the proximal right pulmonary artery may be a specific sign of branch pulmonary artery obstruction. This flow pattern was observed only in infants with
Ann Thorac Surg 1991;51:7>5
ROBERTSON ET AL POSTOPERATIVE PULMONARY ARTERY STENOSIS
75
Fig 3. Frontal main pulmonary artery angiography before (pre) and after (post) pulmona y artery banding demonstrating postoperative stenosis of right pulmonary ortery (curved arrow).
angiographically confirmed branch pulmonary artery obstruction. The mechanism presumably is secondary to encroachment by the pulmonary artery band on the origin of the right pulmonary artery which, in comparison with the left pulmonary artery, arises more proximally and at a more acute angle from the main pulmonary artery. This results in a persistent gradient between the main and branch pulmonary artery, thereby accounting for the continuous Doppler flow profile observed. All of the branch pulmonary artery obstructions reported here involved the right pulmonary artery; however, the small number of patients involved does not permit any conclusions to be made as to the incidence of left pulmonary artery obstruction. Right pulmonary artery obstruction occurred in the presence of an adequate pressure gradient across the pulmonary artery band. The abnormal Doppler flow patterns were not seen in earlier postoperative studies, suggesting that branch pulmonary artery obstruction may be a progressive phenomenon. If recognized before progression to more severe forms of obstruction, it may be possible to intervene early to ultimately avoid more extensive pulmonary artery surgical reconstruction. However, this study does not address the issue of how severe branch pulmonary artery need be before abnormal diastolic flow becomes detectable by Doppler echocardiography. Low flow sensitivity of current color-flow systems may preclude earlier detection of low-velocity continuous diastolic flow associated
with postoperative branch pulmonary artery obstruction. Hence, a clinically significant degree of branch pulmonary artery obstruction may be necessary before detection by Doppler techniques. To avoid branch pulmonary artery obstruction, we now perform pulmonary artery banding using an anterior rather than a lateral thoracotomy, facilitating better visualization of the relationship of the banding material to the proximal right pulmonary artery. Our current approach is to study branch pulmonary flow by Doppler echocardiography early and serially after pulmonary artery banding. The recognition of a diastolic pulmonary artery flow pattern is an indication for pulmonary angiography and either revision of the pulmonary artery band or, when appropriate, early corrective operation.
References 1. Albus RA, Trusler GA, Izukawa T, Williams WG. Pulmonary
artery banding. J Thorac Cardiovasc Surg 1984;88:645-53. 2. Dooley KJ, Lucy PB, Fyler DC, Nadas AS. Results of pulmonary arterial banding in infancy. Survey of 5 years experience in the New England regional infant cardiac program. Am J Cardiol 1985;36:484-8. 3. Stark J. Pulmonary artery banding. In: Stark J, deLaval M, eds. Surgery for congenital heart defects. London: Grune & Stratton, 1983:187-95. 4. Danilowicz D, Prest S, Colvin S. The disappearing pulmonary artery band. Pediatr Cardiol 1990;11:47-9.
