74CC Vul. 0, .N . 2 February 19928x7-X
Lung Perfusion Scans in Patients With Congenital Heart Defects A KIVA TAMIR, MD, MOSHE MELLOUL, MD, MICHAEL BERANT, MD, GMT) .4OEEV, MD, ERNESTO LUBIN, MD, LEONARD C . BLIEDEN, MB . BCrt, BENJAMIN ZEEVI, MD Petntc 7iyvrr net
R'f a l:
In 63 patients with various congenital heart defects, lung perfu . sion was evaluated with technetium-99mm marroaggregated alto . min . Right lung perfusion abnormalities were documented in 34 patients (54%). A particularly high Incidence occurred in patients who had undergone a systemic to pulmonary artery shunt opera . tion as an initial palliative procedure or who had had right ventricular outflow ieconc[ruetion and in those with bilateral pulmonary artery slenosis .
Congenital or postoperative lung perfusion abnormalities in patients with a congenital heart defect may adversely affect their outcome and necessitate special interventions (1-3) . Children with decrea ed lung perfusion . especially if it is uniiatetal . arc usually asvmptomatic and the above conditions are not easily detect, by either chest radiolog, or two-dimensional echocardiography. The marked improvement in recent years (4 .5) in our ahili ;y to directly relieve branch pulmonary artery stenusis . either surgically or with balloon angioplasty . has emphasized the need for an accurate and noninvasive method for quantitative evaluation of tie relative pulmonary blood How in patients with a congenital heart defect . Lung perfusion scintigrams using albumin macroaggregates labeled with technetium-99m have been shown to be an effective method for this assessment 16-10) . In this report we describe our experience with this test i- a heterogeneous group of patients with various congenital heart defects .
Methods Study patients . From January 1989 to July 199(1. 63 patients with a congenital heart defect were studied with hog perfusion scintigrams at the Beilinson Medical Center . There were 26 male and 37 female patients whose age ranged from 6 months to 40 years (mean SD 7 .1 t 6 .6 years) . The medical records, chest X-ray films, two-dimensional and
Fmm the Invrtures of Pediatric Cardiology . PM : Radio'ogy and .m .Nuclear Medicine . Beilinson Medical Center . Pelah T'igoa and !ire SSackler School o+' Medicine. Tel Aria University . Tel Aviv, tsraei . Manuscript received May 16, 1991 : mvired manuscript tnceired tiny 31 . 1991 . accepted August 9 . 1991 . Address for reprm15 : Benjamin Zeevi. MD . Pediatric Cardiology Imtiwte . Beilinson Medical Center. Pelah Tigaa . 49 100 Isael.
Serial studies were helpful in evaluating the functional results or different trarscalheter interventions for optimizing pulmonary
how . The quantitative relative perfusion radionuclide method was a more sensitive means of detecting cases of abnormal lung perfusion than was chest radiology . 11 Am Coll Cardiu(1992 ;19:383-8) blood
Doppler echocardiograms and hemodynamic and cineangio graphic data were reviewed. The indi(otion for bung perfusion scintigraphy was the presence of any congenital heart defector surgical intervenlion that could have affected the distribution of pulmonary blood flow to the lungs. Patients were classified into four groups: I) patients who had undergone a surgical intervention to augment pulmonary blood flow (for example, systemic w pulmonary after ; shunt operation, right ventricular outflow tract reconstruction, complete repair of tetralogy of PalloO; 21 patients who had undergone pulmonary artery Sanding or debanding, or both ; 3) patients who had undergone direct anastomosis of systemic venous pathways to the pulmonary arteries (for example, bidirectional Glenn operation . modified Fonlan operation) : and 4) patients with congenital peripheral pumronary artery stenosis . Informed consent for the procedure hod been obtained from the parents or patient in each case. Lung perfusion scintigraphy . Technetium-99m-labeled macroaggregated albumin in a dose of 0,5 to 2 mCi (18 .5 to 74 .0 MBq) . adjusted to patient weight, was injected through an intravenous cannoli inserted into a peripheral vein . Perfusion imaging was begun almost immediately after injection of the radiopharmaceutical agent with the patient sonine . A standard multiple view scan was performed with use ;)f a large field off view gamma camera (APEX SP-6 . Flscint) equipped with a law energy, all purpose collimator. Four views (anterior . posterior and two posterior oblique views) were obtained . Each view was imaged for 500,000 counts and recorded on transparent multiformat mode . Lung perfusion was calculated as the relative ratio of the sum of radioactivity in each lung in the anterior and posterior views . Inequality of lung perfusion was assessed by an independent of'.cover without . efcreoce to chest X-ray findings or h_rrw dynamic and cineangiograpi ;fc data . Abnormal lung perfu0735-IINLuaS5 .m
1 .. ^.M11 EIAL . , UN(, PER I'I1SION IN CONGENITAL HEART DEFECTS
JACC VOL 19, Nu . 2 February 1992 :303-0
Table 1, Results of Lung Perfusion Scintigraphy in 63 Patients lt,da I-ung Podusum
Figure 1 . Normal lung perfusion scintigress in four views in a patient after repair of tetrnln>v of Fellet (right lung 467, left lung 34%E) . A = anterior view : LP.O. = left posterior oblique view: P = posterior view; R .P .O . = right posterior oblique view .
lion scintigrams were defined as 58% right lung perfusion (Fig . 1) (6) . Chest X-ray studies . The patients' chest X-ray films, obtained within 6 months of the lung perfusion scans without an intervening procedure, were evaluated for pulmonary blood flow in both lung fields by an independent pediatric radiologist without reference to the calculated results of the lung perfusion scintigrams . The chest X-ray films were visually examined according to the method described by Amplatz and Castaneda-Zuniga 11'1 . Arterial blood distribution in each lung was defined as normal . increased or decreased and compared with distribution in the contralaleral lung field . Later, the results were correlated with calculated pulmonary flow distribution by perfusion lung scintigrams . Cineaegiograms . Thirty patients underwent cardiac calheterization and cineangiogmphy within 6 months of the lung perfusion scintigram . Pulmonary artery anatomy was evaluated qualitatively and correlated with the results of the lung perfusion scintigram . All results are presented as mean values SD .
Results Overall results: auttmentation of pulmonary blood Row (Table It . Abnormal lung perfusion scintigrams were found in 34 patients (54%) . Twenty had increased flow to the right lung (range 58% to 90`1c : mean 73 9%) and 14 had decreased flow to the right lung (range 137, to 43% ; mean 32 107).
Of the 44 patients trlur undernent an intercrnliort to augment pulnionan blood flair, 25 (57%) had an abnormal lung perfusion scintigram . Increased flow to the right lung,
Augmmlatimt of pulmonary blood flow in = 44( Left-sided shunt in - 171 Right-vded shunt In = 101 Complete repair of for without a pre-us shunt in = 151 nese11aaeuus 1n = 2) Pulmonary aneryhending (n = III Systemic veins to pulmonary enemy anastomosh In = SI Bilateral peripheral pulmonary artery stenosis in - 3) Totul MeonxSDla) Range
81471 31711 71461
4 (40) 4(27)
91531 31301 4 (27)
141221 32010'4 (370_4J)
20 (RI '30 90,3 58, r90r3
Unless nrherwie indicated. eata show number and percent of paants in each category. TaF = teiralogy of Fallen .
which was present in 17 patients (range 657 to 90% : mean 74 8%), was more common than decreased flow, which was present in 8 patients (range 13% to dS% : mean 31 107) . Of the 27 patients who underwent a systemic to pulmonary artery shunt operation as the initial palliative procedure . 05 (597) had an abnormal lung perfusion scintigram . Seventeen patients underwent a left-sided shunt operation and 9 had increased flow to the right lung, indicating a left pulmonary artery stenosis. Of the 10 patients who underwent a right-sided shunt operation, 4 had decreased flow to the right lung and 3 had increased flow to the right lung, suggesting stenosis of the right pulmonary artery either proximal or distal to the shunt insertion site (Fig . 2) . Fifteen patients with tetralogy of Fallot underwent complete repair without a previous shunt . Eight (537) had abnormal lung perfusion demonstrating peripheral pulmonary artery stenosis . Results with others procedures. Eleven patients underwent pulmonary artery banding, five for a ventricular septal defect and six for various types of single ventricle physiology. Five (457) of these patients had an abnormal lung perfusion scintigram (Fig. 3) ; two of these five were from the single ventricle group, which placed them at high risk for the modified Fontan operation. Five patients underwent either a bidirectional Glenn shunt (n = 2) or a modified Fontan operation (n = 3) ; two of these patients (one from each group) had an abnormal lung perfusion scintigram ; one of these two had a previous pulmonary artery band operation . Of the three patients with congenital peripheral pulmonary artery stenosis, two had an abnormal lung perfusion scintigram . Assessment of interventions : case reports . A repeat lung perfusion scintigram was helpful in evaluating the functional
IA CC 7a1 . 19, No . 2 February 19 2 :11-
TAMIR ET AL. LUNG PFRFI ; SION IN CONGENITAL HEART DEFECTS
Figure 2. A Right ventricular outflow angiogram demonstrating complete occlusion of the proximal right pulmonary artery tarrowl in a patient with pulmonary areruary 7YWt'tNt-s
111 1 SIOV IN i atvii[6ITAL
TAMIa LT AL . liLAIt I' tic_ et Is
tmm-99m macroaggregated albumin injected into a newborn is 0 .03n rad to the whole body and 0 .65 rad to the lungs . This ,toe diminishes rapidly as the patient grows and by ace I year has decreased by nearly two-thirds 1141 . Clinical value. The results of such a relatively noninvasive test enable one to plan further invasive studies such as cardiac cutheterieation and pulmonary artery cineangiograp,hv t, ) . The increased a hay to mr,lorc equal lung perhr van either surgically or with transcatheter interventions such as h : :iloon angioplasty of branch pulmonary arteries I4 .') of toil crdhulu.«ilea f systemic to pulmonary artery collorerd vessels has emphasized the usefulness of this rela :!yety noninvasive. simple and easily rcproduciblc method lair assessing pulmonary blood flow . Our rc,ulis demonstrate that lung perfusion abnormalities arc common (54 ) in children with a congenital heart defect, especiallc after surgical intervention . Most of these patients were asymptomatic, even though they had a grossly about;1,4 ~ang i .,ion scintigram . Similar r cups were doscribed by Gates et al .
5 . A . Anterior view lung perfusion uintigrams in a paurnt with severe right pulmonary artery stenosis after complete rep- of tetralogy of Palla! vthoui a previous hunt oparation . demnn,uaring severe undelpi rfucion 113%) of in. nigh; iorg. R . Aftc, uccv'v fat balloon dilation of the right pulmonary artery . normal peon(46%) of the right lung . Figure
X-ray .`.! :^_= r•'c,n those patients with abnormal lung perfusion were evaluated, correlation was much better . with agree. ment in 17 (63%) of 27 patients .
vhe found that
lung increased from 40 = 4% to
Discussion Perfusion Lot ; scanning is a known and safe means of
assessing regional pulmonary perfusion in children with a congenital heart defect 16-10) . The distribution of the radioactive aggregates between the two lungs is directly proportional to the division of pulmonary artery flow (12) . Safely. Up to 95% of the intravenously injected 10- to 50-gum
radioparticles entering the pulmonary arteries exert
their impact on the capillary or orecapillary bed of the lung . These small particles temporarily occlude one of several hundred thousand capillaries but only I in 1 .500 arterioles . This difference accounts for the >I .000-fold safety factor for nerusion lung scanning . The albumin particles eventualy fragment into smaller components, pass through the capil,ary bed of the lung into the systemic circulation and are phagncytized by hepatic and splenic reticuloendothelial cells . We have used this method without comniications even in cyanotic patients. The halt-time removal rate of the radioactive aggregates from the lung is 4 to 8 h (13) . The absorbed radiation dose resulting from 200 gCi of techne-
1 6 of the 31
children n tth a congenital heart defect had hyperperfusion of one lung . In the present study . lung scanning provided parrfzularly useful information concerning the fate of the pulmonary arteries after a palliative systemic to pulmonary artery shun, operation in patients with various types of cyanotic heart disease and it allowed identification of those pol,rms whh pulmonary artery abnormalities who need special intervention either before or at the time of complete repair . We used this method to assess transcatheter interventions in four patients . Ranger al . ( 4) dr -crihed the use of this method in patents who underwent balloon angioplasty of branch pulmonary arteries . demonstrating that in !0 of their 13 patient, . the mean pulmonary blood flow to the affected 51
I uric peifusion abrormalities may be found in patients after a hidrrecttonal Glenn or a modified Fontan opecation, as in two of our five patients . Similar results have been described by del Torso et al . (10) and are more common when the patient has undergone a previous palliative operation Correlation with other methods . Correlation of roentgenographic and scintigraphic studies showed that the lung perfusion scintigram is more accurate than the other methods studied and that detection of pulmonary blood flow imbalance by inspection of chest X-ray films was possible only when there was grossly unequal pulmonary blood flow . In three of our patients . the lung perfusion scintigram failed to demonstrate significant pulmonary artery stenosis that was well vi;a •.aized by cineangiography . The reason for this is atadca . This gives a sensitivity of 83% and specificity of I00 . Conelasioas. Our results and those of others demonstrate that the lung perfusion scintigram is a relatively easy, reliable and noninvasive method for the accurate determination of relative pulmonary blood flow, a value not easily
AMIR FT AI .. LUNG I'ERPUSIJN IN CONGENITAL JJCAR'I
calculated by other means such as chest radiography and two-dimensional echocardiography . This method allows the detection of changes in pulmonary blood flow and enables one to plan more invasive studies or special transcatheter or surgical interventions.
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IACC Vol. 19 . Nn. 2 February 1992 .383-8 7 . Tong ECK, Liu L, Potter RT. e t al . Macracggregaled RISA lung scan in congenital bean disease . Radiology 1973 :106:585-92 . 9 . Necho WH, Wciss FH, Park SC, Lenox CC, 7 beihuldcr JR, Curtail RG . Pulmonary perfusion defect and bronchi" artery collateral blood flow. JAMA 1977:38x842-4, 9 . Gates GF . Orme HW. Dote EK. The hypeeperrused lung : defection in congenital heart diocese . JAMA 1975 ;233i782-6 . In . dd Torso S, Milanesi 0, for F, n al . Radionuclide exaluation of long perfusion after the Fenian procedure . Im I Cardin) 1988 .20,107-16. 11 . Ampiatz K. Castaneda-Zuniga WR . Evaluationotpulmanary vascularity . In : Gedgaudad E. Stellar JH, Castaned, .Zunigz WR, Ampiatz K, it,, Cardiovascular Radiology. Philadelphia : Win Sounders, 1985:55-63 . 12 . Tow DE. Wagner HL Jr. Lopez-Mutcee V, et al . Validity of measuring regional pulmonary arterial flow with ma-aggregates of human serum albumin. Am 1 Roenigenol Radium The, Neat Men! 1966:96-.664-76. 13 . Taplin GV, Johnson DE. Kennady J C . et al. Aggregated albumin labeled with various rediuivvnpes . In : Andrews GA, Knisely RM . Wagner HL Jr. eds. Radioactive Pharmaceuticals : AEC Symposium Series C . Oak Ridge. TN : U .S. Atomic Energy Commission . Divioion of Technical Informs' Lion. 1966 :525-52. 14 . Webster EW . Alpen NM . Brownell GL. Radiation doses in pediatric nuclear medicine and diagnostic x-ray procedures . In. James AE, Wagner HL Jr. Cooke RE. eds . Pediatric Nuclear Medicine . Philadelphia : WB Saunders . 1974:34-58. 15 . Garcia-Medina V . Bass J . Bnunlin E . et al . A useful projection for demonstrating the bifurcation of the pulmonary anery . Pediete Canliul 1991,11 :147-9.