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Tetralogy of Fallot
The Journal of Pediatrics f
VOL. 35
OCTOBER,
1949
No. 4
Original Communications T E T R A L O G Y OF F A L L O T ANALYSIS OF F O R T Y - 0 N E CASES OF PATIENTS TREATED SURGICALLY AT THE UNIVERSITY OF MINNESOTA HOSPITALS
GEORGIA. B.
PERKINS,M.D.,* MARGARET M. AND M .
J.
HAMMOND,
SHAPIRO,
M.D., P. F.
DWAN,M.D.,
M.D.
MINNEAPOLIS, M I N N .
T one time the achievement of the proper diagnosis of congenital abnormalities of the heart was of almost purely academic interest, serving little practical purpose other than to aid in the evaluation of prognosis in individual cases. Aside from its usefulness in differentiating such abnormalities fro.m rheumatic carditis, its value to the patient was usually minimal. At present, however, as a result of notable advances in the surgical treatment of various types of congenital cardiac defect, added responsibility is placed on the physician, especially the pediatrician, to recognize their presence. The correct diagnosis is as important to the patient in terms of definitive treatment as identification of the causative microorganism is in an infectious disease. Increased interest in the problem of diagnosis has led to the development of a variety of special clinical techniques such as cardiac catheterization and roentgen r a y studies following injection of contrast media, which furnish valuable confirmatory data. Since the presentation in 1945 of a successful method for the surgical treatment of patients with tetralogy of Fallot by Bla]ock and Taussig, 7 the correct diagnosis of this abnormality has become especially important. Concentration of interest on the subject has served to advance our knowledge regarding all types of congenital malformations of the heart. The purpose of the present communication is to review the diagnostic findings and the results of treatment by means of the ]~lalock-Taussig procedure in forty-one tetralogy patients who were admitted to the University of Minnesota Hospital between September, 1946, and December, 1947. In four of these the thoraeotomy was exploratory in character, no attempt being made to carry out the anastomosis; two patients expired during surgery, and the remaining thirty-five had the systemic-puhnonary arterial shunt constructed. The ages of the patients ranged from 18 months to 37 years, the
A
l~rom The Department of Pediatrics~ University of Minnesota, Minneapolis. Minn. All surgical Operations were performed by Dr. John R. Paine and Dr. l~ichard ~Vareo of the D e p a r t m e n t of Surgery. A report of thief surgical experience will be published elsewhere. *Alpha Phi ]=~esearch Fellow in Cardiology~ 401
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m a j o r i t y being between 6 and 8 years. The a v e r a g e age was 8.8 years. F o u r patients were 16 y e a r s of age. The operation was c a r r i e d out on three of these. ANATOMIC AND PHYSIOLOGICCHARACTERISTICSOF TETRAI~OGYOF VALI,OT The tetralogy of Fallot eonsists of tile following f o u r abnormalities: (1) p u l m o n a r y stenosis with n a r r o w i n g of the opening between tile ventriele p r o p e r and the i n f u n d i b u l u m ; (2) i n t e r v e n t r i e u l a r s e p t a l d e f e c t ; (3) dextroposition (with over-riding) of the a o r t a ; and (4) r i g h t v e n t r i e u l a r enlargement. The resulting s y m p t o m s of such abnormalities, namely, a high degree of eyanosis, dyspnea, faintness, possibly syncope, clubbing oi~ the digits, polycythemia, and an increased o x y g e n c a p a c i t y of the blood, occur in v a r y i n g degrees. CLINICALHISTORY Cyanosis is sometimes not p r e s e n t at birth, being noted first either at the time w h e n the duetus arte~'iosus closes or when a r e l a t i v e l y mild p u l m o n a r y or u p p e r r e s p i r a t o r y infection occurs d u r i n g i n f a n c y ; or it m a y not be noted nntil the activity of the p a t i e n t is increased, for example, w h e n he begins to creep. The ductus arterh)sus :is n o r m a l l y c o m p l e t e l y closed b y the third month, although there is constriction or functional closure i m m e d i a t e l y a f t e r birth. ~ Closure m a y be d e l a y e d even f u r t h e r and the duct m a y even r e m a i n patent. There m a y be reopening of the duct later in life. W h y the duetus should close when it is a f u n c t i o n i n g s t r u c t u r e is not known. B a r k l a y and Salmon '~ r e p o r t t h a t two out of ten o p e r a t e d p a t i e n t s were f o u n d to have a small open duct present. W e h a v e seen two patients, both a b o u t 3 y e a r s of age, in w h o m a m a c h i n e r y t y p e m u r m u r was f o u n d to have developed. S u r g e r y was postponed in these eases until p r o p e r e v a l u a t i o n could be made as to the efficiency of the duetus in compensating for tile defect. This observation should lead one to p o s t p o n e s u r g e r y until the age of 3 years, if possible, so t h a t a n y such c o m p e n s a t o r y a t t e m p t s on the p a r t of the b o d y m a y be given an o p p o r t u n i t y to be recognized. I n the p a t i e n t s p r e s e n t e d here, the onset of eyanosis was n o t e d between the time of b i r t h and 5 months in twenty-one cases (51.2 per cent) ; b e t w e e n 6 months and 2 y e a r s in fifteen cases (36.6 per c e n t ) ; between 3 and 7 y e a r s in three eases (7.3 pel' c e n t ) ; and two cases (4.9 per cent) the onset of eyanosis was u n c e r t a i n (Table I ) . Physical endurance was r e s t r i c t e d in v a r y b l g degrees, the distance which the p a t i e n t could Walk on level g r o u n d being used as a good clinical index. Eighteen (43.9 p e r cent) of our patients could w a l k less t h a n one city block; fifteen patients (36.6 per cent) could w a l k f r o m one to two blocks w i t h o u t exhaustion; five patients (12.1 p e r cent) had an endurance of three to six blocks; two patients (4.9 per cent) could go f r o m seven blocks to one mile; and one p a t i e n t (2.5 per cent) was able to w a l k more t h a n one mile. W h e t h e r or not the p a t i e n t s u d d e n l y feels e x h a u s t e d and " s q u a t s " down in his t r a c k s or feels f a t i g u e d but can w a l k into shelter or to a chair are also good indices.
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TETRALOGY O~~ FALLOT
SUh[h,[AI~,Y OIe (]IANiCAI, HISTOI~IES AND P H Y S I C A L S T A T U S
HISTOI~Y Oa STATUS
{
Cyanosis first observed B i r t h to 5 n m n t h s 6 m o n t h s to 2 years 3 years to 7 years Indefinite Physical endurance (walkil~g) Less t h a n I city block 1 to 2 blocks 3 to 6 blocks 7 blocks to 1 mile More t h a n 1 mile H i s t o r y of syncope or convulsions on exertion Physical development Good Fair Poor Occurrence o2 right aortic arch I I e a r t size Normal Slightly enlarged Moderately enlarged Small
~)
51.2 36.6 7.3 4.9 43.9 36.6 12.1 4.9 2.5 36.6 43.9 43.9 12.1 21.9 41.5 34.1 4.9 19.5
Syncope (or a convulsion) f r e q u e n t l y occurs in those severely taxed. Fifteen of our patients (36.6 per cent) experienced this type of symptom. Seven of the ten patients studied by B a r k l a y and Salmon "~ had episodes of syncope. The patient's unwillingness to tolerate anything' which interferes with free breathing such as thutnb-sucking, removal of clothing over the head, washing the face, or blowing the nose, is an indication of his previous experience with and fear of the sensation of suffocation. PHYSICAL EXAMINATION
The I)atient is sometimes undersized and may be somewhat emaciated. The degree of r e t a r d a t i o n in physical development corresponds a p p r o x i m a t e l y with the degree of circulatory deficiency. In the present s t u d y development was f o u n d to be " g o o d " in eighteen patients (43.9 per cent), " f a i r " in eighteen (43.9 per cent) and " p o o r " in five (12.1 per cent). In our patients the degrees, of eyanosis and clubbing of the digits were found to be directly related to the severity of the disease. Spinal kyphosis was f r e q u e n t l y present. The patient is usually v e r y apprehensive, the smaller children showing complete dependence upon the parents. The aortic second sound in a small child is clearly audible in the second left interspace and may be i n t e r p r e t e d as the pulmonic second sound. A normal sinus a r r h y t h m i a is the rule. H e a r t block occasionally results from the septal defect. This condition was not observed in any of our patients. The blood pressure is usually within normal limits, sometimes slightly low. The pulse pressures found here varied from 10 to 50 ram. of mercury, most f r e q u e n t l y being' between 20 and 30 into. There is no unusual relationship between t h a t of the arms and that of_ the legs. lit is f r e q u e n t l y v e r y difficult to obtain the blood pressure, p a r t i c u l a r l y the diastolic. The reason for this is obscure. Olin and Hughes '~ found a v e r y much elevate
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ROENTGEN EXAMINATION
On fluoroscopy the heart shadow is found to be somewhat widened, especially to the ]eft, without m a r k e d cardiac enlargement. Of our cases, the heart size was f o u n d to be normal in seventeen patients (4;[.5 per cent), slightly enlarged in f o u r t e e n (34.1 per cent), more m a r k e d l y enlarged in two (4.9 per cent), and small in eight (19.5 per cent). U n f o r t u n a t e l y , the characteristic boot shape was not always obvious. As a result of the right ventricular enlargement a bifid apex m a y be seen with the notching at the apex indicating the right ventricle below and the left above, the pulsations in each being visible. Although the arch of the aorta usually descends on the left side, it has been demonstrated t h a t it descends on the right side in about one-fifth of the cases. 23 Nine o6 our patients (2.1.9 per cent) showed this abnormality. The importance of this lies in the fact that, since the innominate a r t e r y always lies on the side opposite to that on which the aorta descends, the side on which the incision for s u r g e r y m a y be made will depend upon where the vessel to be used for anastomosis lies. Thirty-two of the thirty-five anastomoses completed in our series of cases were made between the r i g h t or left subclavian a r t e r y and the right or left p u l m o n a r y artery, respectively. The innominate a r t e r y was used in but three cases. Because of the decrease in p u l m o n a r y circulation, the p u l m o n a r y markings are f o u n d to be less m a r k e d t h a n normal. Although not all of the patients in this series showed a high degree of decrease in the p e r i p h e r a l vascular p u l m o n a r y markings, every one showed some decrease in the size of the hilar vessels. The other i m p o r t a n t positive criterion is a small p u l m o n a r y a r t e r y and conus. W e have f o u n d the decrease in pulsations of these vessels to be of more diagnostic aid t h a n is the decrease in vascular markings, since the latter m a y sometimes be equivocal. SPECIAL LABORATORY DATA
Laboratory findings are significant only in so far as t h e y are characteristic of the disease and if they change in the postoperative state. A p o l y c y t h e m i a was invariably present in these patients, the degree being r o u g h l y parallel to the degree of cyanosis and of hypoxemia. It has been f o u n d that, in contrast to the maintenance of a normal relationship between the volume of red cells and the volume of the plasma in po]ycythemia vera, the volume of the plasma in cases of cyanotic heart disease has been found to be below the expected level, 9 thus increasing the oxygen-carrying capacity of the blood at the price of increased viscosity. (TaMe II.) TABLE
II.
HEMOGLOBIN
Preoperative Postoperative
SU~'vIMARY
OF DATA
I:~EGARDING
BLOOD 0 XYGEI'~ SATURA~ TION O~ ~ ARTEI~IAL
EI~YTIIROCYTES
(GIrl. PER ]00 O.C. (]Y[ILLIONSPER BLOOD) eu.l~il~. BLOOD) 12.6-25.6 5.7-12.6 11.1-2] .6 3.5-10.7
]L[ELV[ATOCRIT ( % 1~. B.O.) 50-85 37-75
BLOOD (%) 15.3~86.8 21.2-90.9
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Taussig states that, in children, as long as the o x y g e n s a t u r a t i o n of the arterial blood remains above 66 p e r cent, there is no need for and consequently is no stimulus leading to polycythemia. 22 W e have not always :found this to be true in our series. However, we have :found it true t h a t the h e m a t o c r i t r e a d i n g tends to be lower in those patients w i t h the higher o x y g e n s a t u r a t i ( m vMues. The p r e o p e r a t i v e h e m o g l o b i n values in our group v a r i e d f r o m 12.6 to 25.6 Gm. per 100 e.e.; p o s t o p e r a t i v e l y t h e y r a n g e d f r o m 11.1 to 21.6 Gin. (See Table II.) This r e p r e s e n t e d a decrease of 0.5 to 9 G m. in all of the cases studied a n d a decrease of f r o m 1.9 to 9 Gin. in those with a good result, the a v e r a g e decrease of a b o u t 4 Gin. resulting. The e r y t h r o c y t e count p r e o p e r a t i v e l y was f o u n d to be between 5.67 and 12.6 millions per cubic millimeter ; p o s t o p e r a t i v e l y b e t w e e n 3.5 and 10.7. This r e p r e s e n t s a decrease of 0.2 to 4.6 million cells per cubic millimeter in all the patients and of 0.6 to 4.6 in those w i t h a good result f r o m operation, the average fall being" a b o u t two million. The p r e o p e r a t i v e h e m a t o e r i t values were f o u n d to be b e t w e e n 50 attd 85 p e r cent, whereas p o s t o p e r a t i v e l y t h e y were between 37 and 75 per cent. A decrease in r e a d i n g of 4 to 20 per cent was f o u n d in all of the cases and of 6 to 20 per cent in those with good results, the a v e r a g e fall being a b o u t 13 p e r cent. The decreases in h e m o g l o b i n and h e m a t o c r i t values occur more r a p i d l y (one to three weeks) t h a n the fall in the: e r y t h r o e y t e count, which takes from one to three months. This is in cont r a s t to changes in the degree of o x y g e n s a t u r a t i o n of the a r t e r i a l blood, which changes almost i m m e d i a t e l y a f t e r establishment of the anastomosis. O x y g e n s a t u r a t i o n studies are m a d e both before and a f t e r surgery. This gives c o m p a r a b l e results if the p a t i e n t is u n d e r basal conditions. Therefore, the p a t i e n t is given a r e l a t i v e l y s h o r t anesthetic of B a i r d ' s solution (Pentothal Sodium and curare) rectally and i n t r a v e n o u s l y w h e n the arterial blood is d r a w n to p r e v e n t s t r u g g l i n g and crying. The blood is obtained f r o m the f e m o r a l artery. The m e t h o d most c o m m o n l y used for d e t e r m i n i n g the oxygen content is t h a t of V a n Slyke. ~8 As will be n o t e d later, evaluation of the exercise tolerance shows indications of being m u c h more accurate. Since the degree of o x y g e n s a t u r a t i o n decreases with v o l u n t a r y exertion or crying, evaluation of exercise tolerance has been f o u n d to be easier f r o m a m e c h a n i c a l s t a n d p o i n t and also to be more reliable. I n our series, p r e o p e r a t i v e o x y g e n s a t u r a t i o n values of 15.35 to 86.8 p e r cent were found. P o s t o p e r a t i v e values of 21.2 to 90.9 p e r cent were found. Changes v a r i e d f r o m -0.7 to +54.9 p e r cent in all patients h a v i n g thoraeotomies and b e t w e e n +1.2 and +54.9 per cent in those p a t i e n t s in w h o m a good result was obtained, the a v e r a g e change being f r o m +10 to +25 per cent. I n T a u s s i g ' s 2~ series, the o x y g e n s a t u r a t i o n v a l u e s p r e o p e r a t i v e l y were as low as 13 per cent and as high as 75 p e r cent and rose p o s t o p e r a t i v e l y to as m u c h as 77 per cent, the m a j o r i t y of rises being f r o m 20 to 50 per cent. The conditions u n d e r which these values were obtained, however, are u n k n o w n to us. I n the eases of B a r k l a y and Salmon a the a v e r a g e p r e o p e r a t i v e a r t e r i a l o x y g e n s a t u r a t i o n was 56.4 p e r c e n t ; the a v e r a g e obtained p o s t o p e r a t i v e ] y
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was 80 per cent. The s a t u r a t i o n n e v e r rises to the normal r a n g e of 94. to 97 per cent because of the over-riding of the aorta, an a b n o r m a l i t y which, of course, persists a f t e r surgery. There is a rise in the degree of o x y g e n s a t u r a t i o n w h e n a p a t i e n t is allowed to b r e a t h e a high concentration of oxygen at basal conditions due to art increased oxygen content but with no change in the oxygen capacity. Such studies have r e c e n t l y been carried out in our l a b o r a t o r y , both p r e o p e r a t i v e l y and postoperatively, by having the p a t i e n t b r e a t h e 100 p e r cent o x y g e n a f t e r a sample of arterial blood has been d r a w n for d e t e r m i n a t i o n of the degree of satura,tion, changes being m e a s u r e d b y use of the Milliken-Smaller o x i m e t e r which is to be described shortly. The time necessary for the m a x i m u m sa,turation is noted and either a second sample of a r t e r i a l blood is d r a w n or the percentage increase is indicated by the oximeter readings is recorded. We have f o u n d increases of 6 p e r cent to 15 per cent, but as yet an insufficient n u m b e r of eases have been studied in this m a n n e r to j u s t i f y d r a w i n g final conclusions. I n studies carried out during' the surgical procedure, the increase was noted i m m e d i a t e l y following establishment of a shunt. The s a t u r a t i o n times in ten of the patients on w h o m the test was p e r f o r m e d r a n g e d in p r e o p e r a t i v e times f r o m ten to fifteen minutes, the normal r a n g e being a b o u t three to f o u r lninutes2 ~ P o s t o p e r a t i v e l y the values were within n o r m a l limits. Studies on three of B l a l o c k ' s patients six months, one year, and two y e a r s postoperatively, respectively, also showed normal saturatio,n times, although oxygen saturation studies with reference to their exercise tolerance still showed some ]imitations. '~ Burwell s made the observation that the E i s e n m e n g e r ' s complex could be differentiated from the t e t r a l o g y of Fallot by the short s a t u r a t i o n time in the former. The Milliken-Smaller o x i m e t e r measures the o x y g e n content by r e c o r d i n g electrically the v a r y i n g p h o t o m e t r i c c h a r a c t e r i s t i c s of the blood as determirted by the relative contents of o x y h e m o g l o b i n and r e d u c e d hemoglobin as the blood flows t h r o u g h the lobe of the ear, the readings being obtained in t e r m s of p e r c e n t a g e change. The a d v a n t a g e of using' this method of d e t e r m i n i n g the degree of h y p o x e m i a is t h a t i m m e d i a t e and direct r e a d i n g s m a y be obtained u n d e r v a r y i n g conditions tLs desired. I t s use for this p u r p o s e has been reported elsewhere, a~ A t the present time studies are u n d e r way to determine the effects of a s t a n d a r d a m o u n t of treadmill exercise on the p e r c e n t a g e oxygenation of the blood, thus p r o v i d i n g a more a c c u r a t e and statistically c o m p a r a b l e record of exercise tolerance. Decreases in o x y g e n s a t u r a t i o n are noted and the time necessary for r e t u r n to the original values is recorded ( s a t u r a t i o n time). In ten normal subjects, increases of oxygen s a t u r a t i o n of one to 5 per cent were noted following this exercise, while definite deereases o c c u r r e d in cyanotic patients. Too few p a t i e n t s have been tested as yet, however, to j u s t i f y drawing final conclusions. There is good reason to believe t h a t the c o m p a r a t i v e change in exercise tolerance a f t e r operation is more closely c o r r e l a t e d with the clinical i m p r o v e m e n t of the p a t i e n t than is the change in oxygen s a t u r a tion Ievels. Two of the three p a t i e n t s of Blalock r e f e r r e d to p r e v i o u s l y showed
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a 5 per cent decrease in satm'ation with "extemle~l exercise.'"' llowevcr, preoperative values were not obtained. ()ue patient reported Crom the lmhey Clinic had an oxygen saturation value fifteen days postoperatively which had fallen 5 per eent and seventy-five days postoperatively it had risen only 2 per cent from the preoperative value, although the clinical improvement was good. With the same exercise each time, the drop in oxygen saturation after exercise decreased from a preoperative value of 21 per cent to 9 per cent and then to 2 per cent in fifteen and seventy-five days, respeetivelyY~ The electroeardiogram typieally shows a wide QRS omplitudc, peaking of P and T waves, and marked right axis deviation. These abnormalities were present in all of our patients. Olin and IIughes ~6 reported one patient who had electrocardiographic evidence of eoronary insuNeiency. It has been the opinion of some observers that many children with cyanotic congenital heart disease are mentally retarded. Contrary to this assumption, we have been impressed by the good, and in some eases, unusually good mental development shown. Psychometric examination made by Miss Audrey Areola, clinical psychologist :for the Department of Pediatrics, on thirteen of our l)ao tients picked at random, showed the following' intelligence evaluation: low average, 4; average, 5; slightly above average, 1; and superior, 3. The oxygert saturation values in the " l o w a v e r a g e " group ranged from 49.9 to 86.8 per rent; in the " a v e r a g e " from 43.5 to 75.8 per cent; in the patient "slightly above average," 84.0 per cent; and in the " s u p e r i o r " group from 65.2 to 79,37 per cent. No correlation between the result of the psychometric ewfluation and the preoperative oxygen saturation levels eould be found. Comparison of values for vital capacity, venous pressure, blood volmne, and circulation time may be useful, but too few patients in this series had these determinations made routinely to justify attempts at correlation. Such data as bleeding time and clotting time, carbon-dioxide combining power of the plasma, blood urea nitrogen, and blood chloride levels are obtained preoperatively, both for evaluating the patients' ability to undergo surgery and as a base line for postoperative care. Blood, as well as nose and throat cultures, are taken, and appropriate preoperative chemotherapy is given if necessary to insure aseptic conditions in so far as possible. Dental examination and the preoperative removal of loose teeth has proved a helpful precaution, penicillin being used before and after extraction. I~EOa~nlNa SURGERY While detailed discussion of the surgical procedures employed to ameliorate the circulatory dysfunction in tetralogy of Fallot is quite beyond the scope of this paper, brief comment on certain aspects of the problem is not inappropriate. Obviously, the question regarding the likelihood of the patient's being benefited significantly by operation should be considered of prime importanee in determining the advisability of this form of treatment. Clinical judgment concerning the need for operation and risks involved can be bolstered by information regarding the degree of oxygen saturation of the at-
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terial blood, the patient's exercise tolerance, and the differentia] arterial pressures as measured directly by means of vascular and cardiac catheterization. Preoperative preparation of the patient is of p a r a m o u n t importance. Adequate hydration before operat~ozt tends to obviate the necessity of having to administer fluids intravenously later on. This decreases the d a n g e r of cardiac dilatation and decompensation which may arise secondary to the establishment of the new shunt. Penicillin is given p r o p h y l a c t i c a l l y in large doses for forty-eight hours before s u r g e r y as well as postoperatively. This is given in order that the blood stream m a y be r e n d e r e d as free as possible frora pathogenic penicillin-sensitive microorganisms, since the surgical anastoraosis presents a favorable site for bacteria to collect. The other routine preoperative medications are morphine and atrophine, the f o r m e r being given ia dosages indicated for the age. The atropine is given in relatively large but safe doses in order to depress the vagus nerve sufficiently to c o u n t e r a c t its depressant effect on the heart when the latter is stimulated by unavoidable manipulation during the operation. The dosages in the present eases were 0.6 to 0.3 rag. for patients ranging in age from 6 to 13 years and 0.2 to 0.15 rag. for those patients who were y o u n g e r than 6 years. Application of a local anesthetic to the vagus nerve at the time of s u r g e r y was used to m a g n i f y the effects of atropine. The anesthetic found to be most satisfactory and the one which was used in the last twenty-six of our eases was the pentothal-curare solution described elsewhere by Dr. J. W. Baird 2 of_ the Division of Anesthesiology of the University of Minnesota. Administration of the solution is combined with intra~ tracheal inhalation of_ 50 per cent nitrous oxide and oxygen. Cyclopropane and ether were used originally; however, f o u r fatalities occurred u n d e r these inhalation anesthetics. To what extent anoxia or increased vagal stimulation accounted for these unfortunate results is not definitely known. Since blood must flow after anastomosis f_rom the systemic to the pulmonary circulation, operation is ineffective if the pressure in the latter systera is too high. The maximum p u l m o n a r y arterial pressure used as a guide by the surgeons in our clinic has been that recommended by Blalock, namely, 30 era. of citrate solution. In three of the cases reported here, however, the pressures were 31, 34, and 35 era. of citrate solution, respectively. However, the results of operation on these patients were completely satisfactory. I t is possible that the 30 em. maximum pressure value can be revised u p w a r d for patients having systemic arterial pressures above certain levels. POSTOPERATIVE CHANGES
A continuous murmur is usually heard postoperatively over the site of the anastomosis, sometimes appearing immediately following operation and at other times developing several days or weeks afterward. In nine of our pao tients it was first heard immediately postoperatively; in five it was h e a r d later on the day of the operation. I t was heard on the d a y following operation in three patients; on the third day in five; on the f o u r t h in one; and on the fifth in two. In four other patients it was h e a r d first on the sixth, seventh,
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ninth, and twenty-first p o s t o p e r a t i v e days, respectively. No m u r m u r was h e a r d p o s t o p e r a t i v e l y in seven patients. Of these, two had end-to-end anastomoses (one of the l a t t e r expired and the other had a result of questionable value) a n d three obtained no relief f r o m their symptoms. The sixth p a t i e n t in the g r o u p expired: The r e m a i n i n g one h a d a good result. A l t h o u g h the m u r m u r is h e a r d over the site of the anastomosis, it is often f o u n d to be louder in the b a c k on t h a t side. Oeeasiolmlly, w h e n no new m u r m u r develops, the systolic m u r m u r f o u n d p r e v i o u s l y is accentuated. The lack of a continuous m u r m u r corresponds with the absence of a thrill over the anastomosis immedia t e l y a f t e r it is established. E v e n t h o u g h a thrill is p a l p a b l e below the clavicle a f t e r the chest has been closed, we h a v e f o u n d t h a t it m a y t a k e some time for the m u r m u r to develop. The h e a r t size increases in v a r y i n g degree but not to an a l a r m i n g extent. This increase is p r e d o m i n a n t l y left ventricular. A l t h o u g h the en]arge~ m e n t begins almost immediately, the h e a r t does not usually r e a c h its m a x i m a l size until the end of the second week. E x a m i n a t i o n s as long as several months l a t e r in our cases showed no f u r t h e r increase in h e a r t size. T h a t the m a x i m a l degree of e n l a r g e m e n t occurs almost i m m e d i a t e l y w i t h o u t change t h e r e a f t e r is not surprising. Lewis ~3 has shown t h a t p r o l o n g e d o v e r w o r k does not cause cardiac failure and P a l m e r ~7 has d e m o n s t r a t e d t h a t cardiac e n l a r g e m e n t in essential h y p e r t e n s i o n does not increase a f t e r the blood pressure has been stabilized. The v a s e u l a r i t y of the l u n g field is m o d e r a t e l y increased within a period of one to two weeks in most cases. The increase in the pulsations of the p u l m o n a r y vessels as seen on fluoroscopic examination is also indicative o.f the increase in p u l m o n a r y blood flow. The pulse pressures in our series of cases c h a n g e d as a result of o p e r a t i o n f r o m -7 to +26 mm. of m e r c u r y , w i t h an a v e r a g e of a b o u t 20 ram. increase. These changes are f r e q u e n t l y not as g r e a t as might be expected with a shunt comparable with that in p a t e n t ductus arteriosus h a v i n g been established. The changes show no constant relationship to the operative results. COMPLICATIONS I n our experience simple ioleural effusion was probably the most common postoperative complication encountered, the fluid occurring in significant a m o u n t s in 21 or 50 per cent of the patients. Thoracentesis for relief of r e s p i r a t o r y e m b a r r a s s m e n t -was r e q u i r e d in three cases only. Cultures of the fluid r e m o v e d were usually f o u n d to be sterile. One p a t i e n t expired following r e m o v a l of b u t 20 c.c. f r o m a t o t a l of 1,900 c.c. of fluid in the chest. This d e a t h a p p e a r e d to be due to a sudden shift of the mediastinum.
Chylothorax, occasionally r e s u l t i n g f r o m d a m a g e to the thoracic duct w h e n the ]eft side of the chest is entered, is a more serious complication. I t o c c u r r e d in three patients in this series. All r e q u i r e d r e p e a t e d drainage. One was t a p p e d seventeen times, yielding a total of 9.5 liters of fluid. While the m o r t a l i t y in general chest s u r g e r y complicated by ehylothorax is stated to be as high as 50 per cent, all three of these patients survived.
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The only t h e r a p e u t i c m e a s m ' e indicated in e h y l o t h o r a x other than thoracentesis and c h e m o t h e r a p y is t h a t of m a i n t a i n i n g n o r m M levels of the various blood p l a s m a constituents, such as proteins a n d electrolytes, by either the enteral or a p a r e n t e r a l route, Hevzothorax occurred in two of our patients. One, which was massive and bilateral, was followed b y death. The source of the h e m o r r h a g e was not a d e q u a t e l y e x p l a i n e d at autopsy, the anastomosis being n n r u p t u r e d . Homer's syndrome was f o u n d to. be present shortly a f t e r surgery in four of our patients, the pupil of the eye on the operated side being the smaller of the two. This complication is doubtless due to the f a c t t h a t superior cervical ganglion fibers proceed e r a n i a d via the plexus s u r r o u n d i n g the i n t e r n a l carotid artery. Although the one ease r e p o r t e d f r o m the U n i v e r s i t y of Texas showed no r e t u r n to normal, a ours did. One p a t i e n t in our series showed ptosis and mitosis without changes in sweat secretion. Hoarseness has been :found to oecur p o s t o p e r a t i v e l y by different observers. A l t h o u g h this m a y be the result of the i n t r a t r a e h e a l i n t u b a t i o n only, it m a y also be the result of l a r y n g e a l or s u p r a g l o t t i c edema, being sufficiently severe to require t r a e h e o t o m y . This m e a s u r e was n e c e s s a r y in one p a t i e n t of the present series. Hoarseness m a y also be the result of t e m p o r a r y i n j u r y to the r e c u r r e n t l a r y n g e a l nerve, should the l a t t e r t a k e an a b e r r a n t course. D a m a g e to the phrenie n e r v e is evidenced b y d i a p h r a g m a t i e p a r a l y s i s and b y p a r a d o x i c a l d i a p h r a g m a t i c m o v e m e n t as d e m o n s t r a t e d b y fluoroseopy. This is also usually a t e m p o r a r y finding but is p r e s e n t in spite of the resorption of pleural fluid. W e have observed the complication v e r y f r e q u e n t l y . Hemiplegia m a y occur as a result of a deficient blood supply, especially if the innolninate a r t e r y is used f o r the anastomosis. I t m a y also be the result of an embolus. The hemiplegia m a y or m a y no~t be p e r m a n e n t . The a r m on the side of the operative site remains eool for a v a r y i n g period of time and it m a y be a m a t t e r of months before the t e m p e r a t u r e a p p r o x i m a t e s t h a t of the anoperated side, when a radial pulse m a y then become palpable. We had gangrene of the arm occur in one patient who later expired. Other complications are less common. E m p y e m a , mediastinal shift, pneumothorax, u r i n a r y t r a c t ]nfeetion, and prolonged l e t h a r g y each oeeurred but once among our eases. Thrombosis of the anastomosis occurred in one p a t i e n t also and there was some question of its d e v e l o p m e n t in a second ease. Cardiac decompensation was conspicuously absent in this series. RESULTS OF OPERAU'mN The operative result was e v a l u a t e d f r o m both the clinical and l a b o r a t o r y sl:andpoints, the p a t i e n t s ' s u b j e c t i v e i m p r o v e m e n t being included as an imp o r t a n t eriterion. A good result was obtained in t w e n t y - s i x patients, or 74.3 per cent of those h a v i n g anastomoses p e r f o r m e d . One other p a t i e n t obtained a fair result, two showed questionable results, and f o u r showed no improvemerit. Of those h a v i n g anastomoses completed, five died, giving a m o r t a l i t y of 12.1 per eent. The over-all mot'tality was ]9.~ p e r cent, ineluding deaths in patients who h a d e x p l o r a t o r y thoracotomies w i t h o u t anastomoses and deaths
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which occurred a f t e r the p a t i e n t h a d been discharged from the hospital. BlaIoek and Taussig ~~ had a.u over-all m o r t a l i t y o[ 21 per cent in t h e i r first 243 p a t i e n t s subjected to operation. B a r k l a y a n d Salmon, a in ten patients, had an over-all m o r t a l i t y of 20 pet' cent. Six of their patients were " m u c h imp r o v e d . " M u r r a y ''~ r e p o r t e d a m o r t a l i t y of only 7.3 per cent in 41 eases operated, l[is r e p o r t does not elaborate on the types of patients or on procedures. SUMMARY The c h a r a c t e r i s t i c clinical, roentgenologiea], a n d l a b o r a t o r y f i n d i n g s iu the t e t r a l o g y of F a l l o t t y p e of e o n g e n i t a l h e a r t disease are d i s c u s s e d w i t h p a r t i c u l a r r e f e r e n c e to t h e i r o e c u r r e n e e i n the p a t i e n t s s t u d i e d at t h e Univ e r s i t y of M i n n e s o t a H o s p i t a l . S p e c i a l a t t e n t i o n is called to t h e use of the M i l l i k e n - S m a l l e r o x i m e t e r for d e t e r m i n i n g the a r t e r i a l o x y g e n s a t u r a t i o n w i t h a n d w i t h o u t exereise b o t h b e f o r e a n d a f t e r o p e r a t i o n for e v a l u a t i o n oil the degree of c i r c u l a t o r y i m p r o v e m e n t . The w o r t h - w h i l e n e s s of u s i n g a s t a n d a r d exet'eise toleraztee test as a m e t h o d of d e t e r m i n i n g the d e g r e e of w o r k l i m i t a t i o n b o t h b e f o r e a n d a f t e r o p e r a t i o n is e m p h a s i z e d . A d v a n t a g e s of u s i n g B a i r d ' s p e n t o t h a l c u r a r e s o l u t i o n for a n e s t h e s i a a n d i n c r e a s e d doses of a t r o p i n e s u l f a t e p r e o p e r a t i v e l y , as well as local a p p l i c a t i o n of a n a n e s t h e t i c to the v a g u s n e r v e a t the t i m e of o p e r a t i o n , are m e n t i o n e d briefly. P o s t o p e r a t i v e c h a n g e s i n the c o n s t i t u e n t s of the bh)od a n d in the a c t i o n of the h e a r t are n o t e d . The v a r i o u s p o s t o p e r a t i v e c o m p l i c a t i o n s a n d t h e i r t'elative i n c i d e n e e s are l i s t e d a n d t h e o v e r - a l l o p e r a t i v e r e s u R s i n a series of f o r t y - o n e eases are p r e s e n t e d . REFERENCES I. Abbott, M.: Atlas of Congenital Cardiac Disease, New York, 1936, American Heart Association. 2. Baird, A . T . : Pentothal-Curare Mixture, Anesthesiology 8: 75, 1947. Pentothal-Curare Solution: A Preliminary Report and Analysis of Its Use in 150 Cases, Anesthesiology 9: 14I~ 194& 3. Barklay, H. T., and Salmon~ G. W.: The Blalock-Taussig Operation, J. PFD[AT. 31: 54, 1947. 4. Best, C. H., and Taylor, N. ]3.: Physiological Basis of Medical Praetiee~ ed. 3~ Baltimot% 1943, William Wood & Co.~ pp. 522-523. 5. Blaloek, A.: Use of the Shunt or By-Pass Operation in the Treatment of Arterial Circulation Disorders, Ann. Surg. 125: 129~ 1947. 6. Ibid.: Physiopathology and Surgical Treatment of Congenital Cardiovascular Defects, ;Bull. N. Y. Acad. Meal. 22: 57-80~ 1946. 7. Blaloek, A., and Taussig, H.: The Surgical Treatment of Malformations of the tteart in V(hieh There Is Puhnonary Stenosis or Pulmonary Atresia, J. A. M. A. 128: 189-203, 1945. 8. Burwell~ C. S.: Studies of the Circulation in Congenital Affections of the Heart and Their Application to Some of the Problems of Heart Disease~ Tr. College Physicians 10: 82, 1942. 9. Cassels, D. E., and Morse, M.: Blood Volume in Congenital Heart Diseas% J. PEDIAT. 31: 485, 1947. 10. Gilehrist, A. R.: Surgical Aspects of Congenital Heart Disease, Brit. M. J. 1: 515, 1946. 11. Gulliekson, G., Elam, .I.~ Hammond, M., Paine, d., and Vareo, R.: Oxygen Studies in Congenital Pulmonary Stenosis, Am. Heart .I. 35: 940, 1948. 12. Hawk, P. B., and Bergheim, O.: Practical Physiological Chemistry~ ed. it2~ Philadelphla~ 1947~ The Blakiston Co. 13. Lewis~ T.: Material Relating to Coaretatiott of the Adult Typ% Heart 16: 205~ 1933.
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14. Lundsgaard, C., a n d V a n Slyke, D . D . : Cyanosis. Medical Monographs, vol. 2, Baltimore, ]923, Williams and W i l k i n s Co. 15. Murray, G.: Surgical T r e a t m e n t of Congenital H e a r t Disease (Tetralogy of F a l l o t ) , Canad. Med. Assoc. J. 58: 10, 1948. 16. Olin, C. B., and Hughes, 5. G.: The Blalock Operation for Congenital Pulmonlc Stenosis~ South. Surg. 13: 167, 1947. 17. Palmer, J. H.: The Development of Cardiac E n l a r g e m e n t in Disease of the H e a r t : A Radiologic Study, ]~ed. Research Council Special Report Series, No. 222~ 1937. 18. Peters, J. P., a n d Van Slyke, D. D.: Q u a n t i t a t i v e Clinical Chemistry (Methods), Baltimore, 1932, Williams & %Vilkins Company. 19. Ports, W. J., Smith, S., and Gibson, S.: Anastomosis of the A o r t a to a P u l m o n a r y A r t e r y in Certain Types of Congenital H e a r t Disease. Case Rep. Child. Hosp. Chicago 5: 705, 1946. 20. Rutledge, D. I., a n d Adams, R.: Surgical T r e a t m e n t of Congenital H e a r t Disease: Report of a Case, L a h e y Clin. Bull. 5: 89, 1947. 21. Taussig, H., and Blalock, A.: The Tetralogy of Fallot: Diagnosis and I n d i c a t i o n for Operation; The Surgical T r e a t m e n t of Tetralogy of Fallot~ Surgery 21: ]45, 1946. 22. Ibid.; Observations on the Volume of P u l m o n a r y Circulation and I t s I m p o r t a n c e in the P r o d u c t i o n of Cyanosis and Polycythemia, Am. H e a r t J. 33: 413, 1947. 23. Taussig, H.: Congenital M a l f o r m a t i o n s of the Heart~ ]~ew York, 1947, Commonwealth Fund.
VOL. 35
OCTOBER,
1949
No. 4
Original Communications T E T R A L O G Y OF F A L L O T ANALYSIS OF F O R T Y - 0 N E CASES OF PATIENTS TREATED SURGICALLY AT THE UNIVERSITY OF MINNESOTA HOSPITALS
GEORGIA. B.
PERKINS,M.D.,* MARGARET M. AND M .
J.
HAMMOND,
SHAPIRO,
M.D., P. F.
DWAN,M.D.,
M.D.
MINNEAPOLIS, M I N N .
T one time the achievement of the proper diagnosis of congenital abnormalities of the heart was of almost purely academic interest, serving little practical purpose other than to aid in the evaluation of prognosis in individual cases. Aside from its usefulness in differentiating such abnormalities fro.m rheumatic carditis, its value to the patient was usually minimal. At present, however, as a result of notable advances in the surgical treatment of various types of congenital cardiac defect, added responsibility is placed on the physician, especially the pediatrician, to recognize their presence. The correct diagnosis is as important to the patient in terms of definitive treatment as identification of the causative microorganism is in an infectious disease. Increased interest in the problem of diagnosis has led to the development of a variety of special clinical techniques such as cardiac catheterization and roentgen r a y studies following injection of contrast media, which furnish valuable confirmatory data. Since the presentation in 1945 of a successful method for the surgical treatment of patients with tetralogy of Fallot by Bla]ock and Taussig, 7 the correct diagnosis of this abnormality has become especially important. Concentration of interest on the subject has served to advance our knowledge regarding all types of congenital malformations of the heart. The purpose of the present communication is to review the diagnostic findings and the results of treatment by means of the ]~lalock-Taussig procedure in forty-one tetralogy patients who were admitted to the University of Minnesota Hospital between September, 1946, and December, 1947. In four of these the thoraeotomy was exploratory in character, no attempt being made to carry out the anastomosis; two patients expired during surgery, and the remaining thirty-five had the systemic-puhnonary arterial shunt constructed. The ages of the patients ranged from 18 months to 37 years, the
A
l~rom The Department of Pediatrics~ University of Minnesota, Minneapolis. Minn. All surgical Operations were performed by Dr. John R. Paine and Dr. l~ichard ~Vareo of the D e p a r t m e n t of Surgery. A report of thief surgical experience will be published elsewhere. *Alpha Phi ]=~esearch Fellow in Cardiology~ 401
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m a j o r i t y being between 6 and 8 years. The a v e r a g e age was 8.8 years. F o u r patients were 16 y e a r s of age. The operation was c a r r i e d out on three of these. ANATOMIC AND PHYSIOLOGICCHARACTERISTICSOF TETRAI~OGYOF VALI,OT The tetralogy of Fallot eonsists of tile following f o u r abnormalities: (1) p u l m o n a r y stenosis with n a r r o w i n g of the opening between tile ventriele p r o p e r and the i n f u n d i b u l u m ; (2) i n t e r v e n t r i e u l a r s e p t a l d e f e c t ; (3) dextroposition (with over-riding) of the a o r t a ; and (4) r i g h t v e n t r i e u l a r enlargement. The resulting s y m p t o m s of such abnormalities, namely, a high degree of eyanosis, dyspnea, faintness, possibly syncope, clubbing oi~ the digits, polycythemia, and an increased o x y g e n c a p a c i t y of the blood, occur in v a r y i n g degrees. CLINICALHISTORY Cyanosis is sometimes not p r e s e n t at birth, being noted first either at the time w h e n the duetus arte~'iosus closes or when a r e l a t i v e l y mild p u l m o n a r y or u p p e r r e s p i r a t o r y infection occurs d u r i n g i n f a n c y ; or it m a y not be noted nntil the activity of the p a t i e n t is increased, for example, w h e n he begins to creep. The ductus arterh)sus :is n o r m a l l y c o m p l e t e l y closed b y the third month, although there is constriction or functional closure i m m e d i a t e l y a f t e r birth. ~ Closure m a y be d e l a y e d even f u r t h e r and the duct m a y even r e m a i n patent. There m a y be reopening of the duct later in life. W h y the duetus should close when it is a f u n c t i o n i n g s t r u c t u r e is not known. B a r k l a y and Salmon '~ r e p o r t t h a t two out of ten o p e r a t e d p a t i e n t s were f o u n d to have a small open duct present. W e h a v e seen two patients, both a b o u t 3 y e a r s of age, in w h o m a m a c h i n e r y t y p e m u r m u r was f o u n d to have developed. S u r g e r y was postponed in these eases until p r o p e r e v a l u a t i o n could be made as to the efficiency of the duetus in compensating for tile defect. This observation should lead one to p o s t p o n e s u r g e r y until the age of 3 years, if possible, so t h a t a n y such c o m p e n s a t o r y a t t e m p t s on the p a r t of the b o d y m a y be given an o p p o r t u n i t y to be recognized. I n the p a t i e n t s p r e s e n t e d here, the onset of eyanosis was n o t e d between the time of b i r t h and 5 months in twenty-one cases (51.2 per cent) ; b e t w e e n 6 months and 2 y e a r s in fifteen cases (36.6 per c e n t ) ; between 3 and 7 y e a r s in three eases (7.3 pel' c e n t ) ; and two cases (4.9 per cent) the onset of eyanosis was u n c e r t a i n (Table I ) . Physical endurance was r e s t r i c t e d in v a r y b l g degrees, the distance which the p a t i e n t could Walk on level g r o u n d being used as a good clinical index. Eighteen (43.9 p e r cent) of our patients could w a l k less t h a n one city block; fifteen patients (36.6 per cent) could w a l k f r o m one to two blocks w i t h o u t exhaustion; five patients (12.1 p e r cent) had an endurance of three to six blocks; two patients (4.9 per cent) could go f r o m seven blocks to one mile; and one p a t i e n t (2.5 per cent) was able to w a l k more t h a n one mile. W h e t h e r or not the p a t i e n t s u d d e n l y feels e x h a u s t e d and " s q u a t s " down in his t r a c k s or feels f a t i g u e d but can w a l k into shelter or to a chair are also good indices.
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TETRALOGY O~~ FALLOT
SUh[h,[AI~,Y OIe (]IANiCAI, HISTOI~IES AND P H Y S I C A L S T A T U S
HISTOI~Y Oa STATUS
{
Cyanosis first observed B i r t h to 5 n m n t h s 6 m o n t h s to 2 years 3 years to 7 years Indefinite Physical endurance (walkil~g) Less t h a n I city block 1 to 2 blocks 3 to 6 blocks 7 blocks to 1 mile More t h a n 1 mile H i s t o r y of syncope or convulsions on exertion Physical development Good Fair Poor Occurrence o2 right aortic arch I I e a r t size Normal Slightly enlarged Moderately enlarged Small
~)
51.2 36.6 7.3 4.9 43.9 36.6 12.1 4.9 2.5 36.6 43.9 43.9 12.1 21.9 41.5 34.1 4.9 19.5
Syncope (or a convulsion) f r e q u e n t l y occurs in those severely taxed. Fifteen of our patients (36.6 per cent) experienced this type of symptom. Seven of the ten patients studied by B a r k l a y and Salmon "~ had episodes of syncope. The patient's unwillingness to tolerate anything' which interferes with free breathing such as thutnb-sucking, removal of clothing over the head, washing the face, or blowing the nose, is an indication of his previous experience with and fear of the sensation of suffocation. PHYSICAL EXAMINATION
The I)atient is sometimes undersized and may be somewhat emaciated. The degree of r e t a r d a t i o n in physical development corresponds a p p r o x i m a t e l y with the degree of circulatory deficiency. In the present s t u d y development was f o u n d to be " g o o d " in eighteen patients (43.9 per cent), " f a i r " in eighteen (43.9 per cent) and " p o o r " in five (12.1 per cent). In our patients the degrees, of eyanosis and clubbing of the digits were found to be directly related to the severity of the disease. Spinal kyphosis was f r e q u e n t l y present. The patient is usually v e r y apprehensive, the smaller children showing complete dependence upon the parents. The aortic second sound in a small child is clearly audible in the second left interspace and may be i n t e r p r e t e d as the pulmonic second sound. A normal sinus a r r h y t h m i a is the rule. H e a r t block occasionally results from the septal defect. This condition was not observed in any of our patients. The blood pressure is usually within normal limits, sometimes slightly low. The pulse pressures found here varied from 10 to 50 ram. of mercury, most f r e q u e n t l y being' between 20 and 30 into. There is no unusual relationship between t h a t of the arms and that of_ the legs. lit is f r e q u e n t l y v e r y difficult to obtain the blood pressure, p a r t i c u l a r l y the diastolic. The reason for this is obscure. Olin and Hughes '~ found a v e r y much elevate
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ROENTGEN EXAMINATION
On fluoroscopy the heart shadow is found to be somewhat widened, especially to the ]eft, without m a r k e d cardiac enlargement. Of our cases, the heart size was f o u n d to be normal in seventeen patients (4;[.5 per cent), slightly enlarged in f o u r t e e n (34.1 per cent), more m a r k e d l y enlarged in two (4.9 per cent), and small in eight (19.5 per cent). U n f o r t u n a t e l y , the characteristic boot shape was not always obvious. As a result of the right ventricular enlargement a bifid apex m a y be seen with the notching at the apex indicating the right ventricle below and the left above, the pulsations in each being visible. Although the arch of the aorta usually descends on the left side, it has been demonstrated t h a t it descends on the right side in about one-fifth of the cases. 23 Nine o6 our patients (2.1.9 per cent) showed this abnormality. The importance of this lies in the fact that, since the innominate a r t e r y always lies on the side opposite to that on which the aorta descends, the side on which the incision for s u r g e r y m a y be made will depend upon where the vessel to be used for anastomosis lies. Thirty-two of the thirty-five anastomoses completed in our series of cases were made between the r i g h t or left subclavian a r t e r y and the right or left p u l m o n a r y artery, respectively. The innominate a r t e r y was used in but three cases. Because of the decrease in p u l m o n a r y circulation, the p u l m o n a r y markings are f o u n d to be less m a r k e d t h a n normal. Although not all of the patients in this series showed a high degree of decrease in the p e r i p h e r a l vascular p u l m o n a r y markings, every one showed some decrease in the size of the hilar vessels. The other i m p o r t a n t positive criterion is a small p u l m o n a r y a r t e r y and conus. W e have f o u n d the decrease in pulsations of these vessels to be of more diagnostic aid t h a n is the decrease in vascular markings, since the latter m a y sometimes be equivocal. SPECIAL LABORATORY DATA
Laboratory findings are significant only in so far as t h e y are characteristic of the disease and if they change in the postoperative state. A p o l y c y t h e m i a was invariably present in these patients, the degree being r o u g h l y parallel to the degree of cyanosis and of hypoxemia. It has been f o u n d that, in contrast to the maintenance of a normal relationship between the volume of red cells and the volume of the plasma in po]ycythemia vera, the volume of the plasma in cases of cyanotic heart disease has been found to be below the expected level, 9 thus increasing the oxygen-carrying capacity of the blood at the price of increased viscosity. (TaMe II.) TABLE
II.
HEMOGLOBIN
Preoperative Postoperative
SU~'vIMARY
OF DATA
I:~EGARDING
BLOOD 0 XYGEI'~ SATURA~ TION O~ ~ ARTEI~IAL
EI~YTIIROCYTES
(GIrl. PER ]00 O.C. (]Y[ILLIONSPER BLOOD) eu.l~il~. BLOOD) 12.6-25.6 5.7-12.6 11.1-2] .6 3.5-10.7
]L[ELV[ATOCRIT ( % 1~. B.O.) 50-85 37-75
BLOOD (%) 15.3~86.8 21.2-90.9
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Taussig states that, in children, as long as the o x y g e n s a t u r a t i o n of the arterial blood remains above 66 p e r cent, there is no need for and consequently is no stimulus leading to polycythemia. 22 W e have not always :found this to be true in our series. However, we have :found it true t h a t the h e m a t o c r i t r e a d i n g tends to be lower in those patients w i t h the higher o x y g e n s a t u r a t i ( m vMues. The p r e o p e r a t i v e h e m o g l o b i n values in our group v a r i e d f r o m 12.6 to 25.6 Gm. per 100 e.e.; p o s t o p e r a t i v e l y t h e y r a n g e d f r o m 11.1 to 21.6 Gin. (See Table II.) This r e p r e s e n t e d a decrease of 0.5 to 9 G m. in all of the cases studied a n d a decrease of f r o m 1.9 to 9 Gin. in those with a good result, the a v e r a g e decrease of a b o u t 4 Gin. resulting. The e r y t h r o c y t e count p r e o p e r a t i v e l y was f o u n d to be between 5.67 and 12.6 millions per cubic millimeter ; p o s t o p e r a t i v e l y b e t w e e n 3.5 and 10.7. This r e p r e s e n t s a decrease of 0.2 to 4.6 million cells per cubic millimeter in all the patients and of 0.6 to 4.6 in those w i t h a good result f r o m operation, the average fall being" a b o u t two million. The p r e o p e r a t i v e h e m a t o e r i t values were f o u n d to be b e t w e e n 50 attd 85 p e r cent, whereas p o s t o p e r a t i v e l y t h e y were between 37 and 75 per cent. A decrease in r e a d i n g of 4 to 20 per cent was f o u n d in all of the cases and of 6 to 20 per cent in those with good results, the a v e r a g e fall being a b o u t 13 p e r cent. The decreases in h e m o g l o b i n and h e m a t o c r i t values occur more r a p i d l y (one to three weeks) t h a n the fall in the: e r y t h r o e y t e count, which takes from one to three months. This is in cont r a s t to changes in the degree of o x y g e n s a t u r a t i o n of the a r t e r i a l blood, which changes almost i m m e d i a t e l y a f t e r establishment of the anastomosis. O x y g e n s a t u r a t i o n studies are m a d e both before and a f t e r surgery. This gives c o m p a r a b l e results if the p a t i e n t is u n d e r basal conditions. Therefore, the p a t i e n t is given a r e l a t i v e l y s h o r t anesthetic of B a i r d ' s solution (Pentothal Sodium and curare) rectally and i n t r a v e n o u s l y w h e n the arterial blood is d r a w n to p r e v e n t s t r u g g l i n g and crying. The blood is obtained f r o m the f e m o r a l artery. The m e t h o d most c o m m o n l y used for d e t e r m i n i n g the oxygen content is t h a t of V a n Slyke. ~8 As will be n o t e d later, evaluation of the exercise tolerance shows indications of being m u c h more accurate. Since the degree of o x y g e n s a t u r a t i o n decreases with v o l u n t a r y exertion or crying, evaluation of exercise tolerance has been f o u n d to be easier f r o m a m e c h a n i c a l s t a n d p o i n t and also to be more reliable. I n our series, p r e o p e r a t i v e o x y g e n s a t u r a t i o n values of 15.35 to 86.8 p e r cent were found. P o s t o p e r a t i v e values of 21.2 to 90.9 p e r cent were found. Changes v a r i e d f r o m -0.7 to +54.9 p e r cent in all patients h a v i n g thoraeotomies and b e t w e e n +1.2 and +54.9 per cent in those p a t i e n t s in w h o m a good result was obtained, the a v e r a g e change being f r o m +10 to +25 per cent. I n T a u s s i g ' s 2~ series, the o x y g e n s a t u r a t i o n v a l u e s p r e o p e r a t i v e l y were as low as 13 per cent and as high as 75 p e r cent and rose p o s t o p e r a t i v e l y to as m u c h as 77 per cent, the m a j o r i t y of rises being f r o m 20 to 50 per cent. The conditions u n d e r which these values were obtained, however, are u n k n o w n to us. I n the eases of B a r k l a y and Salmon a the a v e r a g e p r e o p e r a t i v e a r t e r i a l o x y g e n s a t u r a t i o n was 56.4 p e r c e n t ; the a v e r a g e obtained p o s t o p e r a t i v e ] y
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was 80 per cent. The s a t u r a t i o n n e v e r rises to the normal r a n g e of 94. to 97 per cent because of the over-riding of the aorta, an a b n o r m a l i t y which, of course, persists a f t e r surgery. There is a rise in the degree of o x y g e n s a t u r a t i o n w h e n a p a t i e n t is allowed to b r e a t h e a high concentration of oxygen at basal conditions due to art increased oxygen content but with no change in the oxygen capacity. Such studies have r e c e n t l y been carried out in our l a b o r a t o r y , both p r e o p e r a t i v e l y and postoperatively, by having the p a t i e n t b r e a t h e 100 p e r cent o x y g e n a f t e r a sample of arterial blood has been d r a w n for d e t e r m i n a t i o n of the degree of satura,tion, changes being m e a s u r e d b y use of the Milliken-Smaller o x i m e t e r which is to be described shortly. The time necessary for the m a x i m u m sa,turation is noted and either a second sample of a r t e r i a l blood is d r a w n or the percentage increase is indicated by the oximeter readings is recorded. We have f o u n d increases of 6 p e r cent to 15 per cent, but as yet an insufficient n u m b e r of eases have been studied in this m a n n e r to j u s t i f y d r a w i n g final conclusions. I n studies carried out during' the surgical procedure, the increase was noted i m m e d i a t e l y following establishment of a shunt. The s a t u r a t i o n times in ten of the patients on w h o m the test was p e r f o r m e d r a n g e d in p r e o p e r a t i v e times f r o m ten to fifteen minutes, the normal r a n g e being a b o u t three to f o u r lninutes2 ~ P o s t o p e r a t i v e l y the values were within n o r m a l limits. Studies on three of B l a l o c k ' s patients six months, one year, and two y e a r s postoperatively, respectively, also showed normal saturatio,n times, although oxygen saturation studies with reference to their exercise tolerance still showed some ]imitations. '~ Burwell s made the observation that the E i s e n m e n g e r ' s complex could be differentiated from the t e t r a l o g y of Fallot by the short s a t u r a t i o n time in the former. The Milliken-Smaller o x i m e t e r measures the o x y g e n content by r e c o r d i n g electrically the v a r y i n g p h o t o m e t r i c c h a r a c t e r i s t i c s of the blood as determirted by the relative contents of o x y h e m o g l o b i n and r e d u c e d hemoglobin as the blood flows t h r o u g h the lobe of the ear, the readings being obtained in t e r m s of p e r c e n t a g e change. The a d v a n t a g e of using' this method of d e t e r m i n i n g the degree of h y p o x e m i a is t h a t i m m e d i a t e and direct r e a d i n g s m a y be obtained u n d e r v a r y i n g conditions tLs desired. I t s use for this p u r p o s e has been reported elsewhere, a~ A t the present time studies are u n d e r way to determine the effects of a s t a n d a r d a m o u n t of treadmill exercise on the p e r c e n t a g e oxygenation of the blood, thus p r o v i d i n g a more a c c u r a t e and statistically c o m p a r a b l e record of exercise tolerance. Decreases in o x y g e n s a t u r a t i o n are noted and the time necessary for r e t u r n to the original values is recorded ( s a t u r a t i o n time). In ten normal subjects, increases of oxygen s a t u r a t i o n of one to 5 per cent were noted following this exercise, while definite deereases o c c u r r e d in cyanotic patients. Too few p a t i e n t s have been tested as yet, however, to j u s t i f y drawing final conclusions. There is good reason to believe t h a t the c o m p a r a t i v e change in exercise tolerance a f t e r operation is more closely c o r r e l a t e d with the clinical i m p r o v e m e n t of the p a t i e n t than is the change in oxygen s a t u r a tion Ievels. Two of the three p a t i e n t s of Blalock r e f e r r e d to p r e v i o u s l y showed
PERKINS
ET AL. :
T E T R A L O G Y OF F A L L O T
~07
a 5 per cent decrease in satm'ation with "extemle~l exercise.'"' llowevcr, preoperative values were not obtained. ()ue patient reported Crom the lmhey Clinic had an oxygen saturation value fifteen days postoperatively which had fallen 5 per eent and seventy-five days postoperatively it had risen only 2 per cent from the preoperative value, although the clinical improvement was good. With the same exercise each time, the drop in oxygen saturation after exercise decreased from a preoperative value of 21 per cent to 9 per cent and then to 2 per cent in fifteen and seventy-five days, respeetivelyY~ The electroeardiogram typieally shows a wide QRS omplitudc, peaking of P and T waves, and marked right axis deviation. These abnormalities were present in all of our patients. Olin and IIughes ~6 reported one patient who had electrocardiographic evidence of eoronary insuNeiency. It has been the opinion of some observers that many children with cyanotic congenital heart disease are mentally retarded. Contrary to this assumption, we have been impressed by the good, and in some eases, unusually good mental development shown. Psychometric examination made by Miss Audrey Areola, clinical psychologist :for the Department of Pediatrics, on thirteen of our l)ao tients picked at random, showed the following' intelligence evaluation: low average, 4; average, 5; slightly above average, 1; and superior, 3. The oxygert saturation values in the " l o w a v e r a g e " group ranged from 49.9 to 86.8 per rent; in the " a v e r a g e " from 43.5 to 75.8 per cent; in the patient "slightly above average," 84.0 per cent; and in the " s u p e r i o r " group from 65.2 to 79,37 per cent. No correlation between the result of the psychometric ewfluation and the preoperative oxygen saturation levels eould be found. Comparison of values for vital capacity, venous pressure, blood volmne, and circulation time may be useful, but too few patients in this series had these determinations made routinely to justify attempts at correlation. Such data as bleeding time and clotting time, carbon-dioxide combining power of the plasma, blood urea nitrogen, and blood chloride levels are obtained preoperatively, both for evaluating the patients' ability to undergo surgery and as a base line for postoperative care. Blood, as well as nose and throat cultures, are taken, and appropriate preoperative chemotherapy is given if necessary to insure aseptic conditions in so far as possible. Dental examination and the preoperative removal of loose teeth has proved a helpful precaution, penicillin being used before and after extraction. I~EOa~nlNa SURGERY While detailed discussion of the surgical procedures employed to ameliorate the circulatory dysfunction in tetralogy of Fallot is quite beyond the scope of this paper, brief comment on certain aspects of the problem is not inappropriate. Obviously, the question regarding the likelihood of the patient's being benefited significantly by operation should be considered of prime importanee in determining the advisability of this form of treatment. Clinical judgment concerning the need for operation and risks involved can be bolstered by information regarding the degree of oxygen saturation of the at-
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THE JOURNAL OF PEDIATRICS
terial blood, the patient's exercise tolerance, and the differentia] arterial pressures as measured directly by means of vascular and cardiac catheterization. Preoperative preparation of the patient is of p a r a m o u n t importance. Adequate hydration before operat~ozt tends to obviate the necessity of having to administer fluids intravenously later on. This decreases the d a n g e r of cardiac dilatation and decompensation which may arise secondary to the establishment of the new shunt. Penicillin is given p r o p h y l a c t i c a l l y in large doses for forty-eight hours before s u r g e r y as well as postoperatively. This is given in order that the blood stream m a y be r e n d e r e d as free as possible frora pathogenic penicillin-sensitive microorganisms, since the surgical anastoraosis presents a favorable site for bacteria to collect. The other routine preoperative medications are morphine and atrophine, the f o r m e r being given ia dosages indicated for the age. The atropine is given in relatively large but safe doses in order to depress the vagus nerve sufficiently to c o u n t e r a c t its depressant effect on the heart when the latter is stimulated by unavoidable manipulation during the operation. The dosages in the present eases were 0.6 to 0.3 rag. for patients ranging in age from 6 to 13 years and 0.2 to 0.15 rag. for those patients who were y o u n g e r than 6 years. Application of a local anesthetic to the vagus nerve at the time of s u r g e r y was used to m a g n i f y the effects of atropine. The anesthetic found to be most satisfactory and the one which was used in the last twenty-six of our eases was the pentothal-curare solution described elsewhere by Dr. J. W. Baird 2 of_ the Division of Anesthesiology of the University of Minnesota. Administration of the solution is combined with intra~ tracheal inhalation of_ 50 per cent nitrous oxide and oxygen. Cyclopropane and ether were used originally; however, f o u r fatalities occurred u n d e r these inhalation anesthetics. To what extent anoxia or increased vagal stimulation accounted for these unfortunate results is not definitely known. Since blood must flow after anastomosis f_rom the systemic to the pulmonary circulation, operation is ineffective if the pressure in the latter systera is too high. The maximum p u l m o n a r y arterial pressure used as a guide by the surgeons in our clinic has been that recommended by Blalock, namely, 30 era. of citrate solution. In three of the cases reported here, however, the pressures were 31, 34, and 35 era. of citrate solution, respectively. However, the results of operation on these patients were completely satisfactory. I t is possible that the 30 em. maximum pressure value can be revised u p w a r d for patients having systemic arterial pressures above certain levels. POSTOPERATIVE CHANGES
A continuous murmur is usually heard postoperatively over the site of the anastomosis, sometimes appearing immediately following operation and at other times developing several days or weeks afterward. In nine of our pao tients it was first heard immediately postoperatively; in five it was h e a r d later on the day of the operation. I t was heard on the d a y following operation in three patients; on the third day in five; on the f o u r t h in one; and on the fifth in two. In four other patients it was h e a r d first on the sixth, seventh,
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409
ninth, and twenty-first p o s t o p e r a t i v e days, respectively. No m u r m u r was h e a r d p o s t o p e r a t i v e l y in seven patients. Of these, two had end-to-end anastomoses (one of the l a t t e r expired and the other had a result of questionable value) a n d three obtained no relief f r o m their symptoms. The sixth p a t i e n t in the g r o u p expired: The r e m a i n i n g one h a d a good result. A l t h o u g h the m u r m u r is h e a r d over the site of the anastomosis, it is often f o u n d to be louder in the b a c k on t h a t side. Oeeasiolmlly, w h e n no new m u r m u r develops, the systolic m u r m u r f o u n d p r e v i o u s l y is accentuated. The lack of a continuous m u r m u r corresponds with the absence of a thrill over the anastomosis immedia t e l y a f t e r it is established. E v e n t h o u g h a thrill is p a l p a b l e below the clavicle a f t e r the chest has been closed, we h a v e f o u n d t h a t it m a y t a k e some time for the m u r m u r to develop. The h e a r t size increases in v a r y i n g degree but not to an a l a r m i n g extent. This increase is p r e d o m i n a n t l y left ventricular. A l t h o u g h the en]arge~ m e n t begins almost immediately, the h e a r t does not usually r e a c h its m a x i m a l size until the end of the second week. E x a m i n a t i o n s as long as several months l a t e r in our cases showed no f u r t h e r increase in h e a r t size. T h a t the m a x i m a l degree of e n l a r g e m e n t occurs almost i m m e d i a t e l y w i t h o u t change t h e r e a f t e r is not surprising. Lewis ~3 has shown t h a t p r o l o n g e d o v e r w o r k does not cause cardiac failure and P a l m e r ~7 has d e m o n s t r a t e d t h a t cardiac e n l a r g e m e n t in essential h y p e r t e n s i o n does not increase a f t e r the blood pressure has been stabilized. The v a s e u l a r i t y of the l u n g field is m o d e r a t e l y increased within a period of one to two weeks in most cases. The increase in the pulsations of the p u l m o n a r y vessels as seen on fluoroscopic examination is also indicative o.f the increase in p u l m o n a r y blood flow. The pulse pressures in our series of cases c h a n g e d as a result of o p e r a t i o n f r o m -7 to +26 mm. of m e r c u r y , w i t h an a v e r a g e of a b o u t 20 ram. increase. These changes are f r e q u e n t l y not as g r e a t as might be expected with a shunt comparable with that in p a t e n t ductus arteriosus h a v i n g been established. The changes show no constant relationship to the operative results. COMPLICATIONS I n our experience simple ioleural effusion was probably the most common postoperative complication encountered, the fluid occurring in significant a m o u n t s in 21 or 50 per cent of the patients. Thoracentesis for relief of r e s p i r a t o r y e m b a r r a s s m e n t -was r e q u i r e d in three cases only. Cultures of the fluid r e m o v e d were usually f o u n d to be sterile. One p a t i e n t expired following r e m o v a l of b u t 20 c.c. f r o m a t o t a l of 1,900 c.c. of fluid in the chest. This d e a t h a p p e a r e d to be due to a sudden shift of the mediastinum.
Chylothorax, occasionally r e s u l t i n g f r o m d a m a g e to the thoracic duct w h e n the ]eft side of the chest is entered, is a more serious complication. I t o c c u r r e d in three patients in this series. All r e q u i r e d r e p e a t e d drainage. One was t a p p e d seventeen times, yielding a total of 9.5 liters of fluid. While the m o r t a l i t y in general chest s u r g e r y complicated by ehylothorax is stated to be as high as 50 per cent, all three of these patients survived.
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The only t h e r a p e u t i c m e a s m ' e indicated in e h y l o t h o r a x other than thoracentesis and c h e m o t h e r a p y is t h a t of m a i n t a i n i n g n o r m M levels of the various blood p l a s m a constituents, such as proteins a n d electrolytes, by either the enteral or a p a r e n t e r a l route, Hevzothorax occurred in two of our patients. One, which was massive and bilateral, was followed b y death. The source of the h e m o r r h a g e was not a d e q u a t e l y e x p l a i n e d at autopsy, the anastomosis being n n r u p t u r e d . Homer's syndrome was f o u n d to. be present shortly a f t e r surgery in four of our patients, the pupil of the eye on the operated side being the smaller of the two. This complication is doubtless due to the f a c t t h a t superior cervical ganglion fibers proceed e r a n i a d via the plexus s u r r o u n d i n g the i n t e r n a l carotid artery. Although the one ease r e p o r t e d f r o m the U n i v e r s i t y of Texas showed no r e t u r n to normal, a ours did. One p a t i e n t in our series showed ptosis and mitosis without changes in sweat secretion. Hoarseness has been :found to oecur p o s t o p e r a t i v e l y by different observers. A l t h o u g h this m a y be the result of the i n t r a t r a e h e a l i n t u b a t i o n only, it m a y also be the result of l a r y n g e a l or s u p r a g l o t t i c edema, being sufficiently severe to require t r a e h e o t o m y . This m e a s u r e was n e c e s s a r y in one p a t i e n t of the present series. Hoarseness m a y also be the result of t e m p o r a r y i n j u r y to the r e c u r r e n t l a r y n g e a l nerve, should the l a t t e r t a k e an a b e r r a n t course. D a m a g e to the phrenie n e r v e is evidenced b y d i a p h r a g m a t i e p a r a l y s i s and b y p a r a d o x i c a l d i a p h r a g m a t i c m o v e m e n t as d e m o n s t r a t e d b y fluoroseopy. This is also usually a t e m p o r a r y finding but is p r e s e n t in spite of the resorption of pleural fluid. W e have observed the complication v e r y f r e q u e n t l y . Hemiplegia m a y occur as a result of a deficient blood supply, especially if the innolninate a r t e r y is used f o r the anastomosis. I t m a y also be the result of an embolus. The hemiplegia m a y or m a y no~t be p e r m a n e n t . The a r m on the side of the operative site remains eool for a v a r y i n g period of time and it m a y be a m a t t e r of months before the t e m p e r a t u r e a p p r o x i m a t e s t h a t of the anoperated side, when a radial pulse m a y then become palpable. We had gangrene of the arm occur in one patient who later expired. Other complications are less common. E m p y e m a , mediastinal shift, pneumothorax, u r i n a r y t r a c t ]nfeetion, and prolonged l e t h a r g y each oeeurred but once among our eases. Thrombosis of the anastomosis occurred in one p a t i e n t also and there was some question of its d e v e l o p m e n t in a second ease. Cardiac decompensation was conspicuously absent in this series. RESULTS OF OPERAU'mN The operative result was e v a l u a t e d f r o m both the clinical and l a b o r a t o r y sl:andpoints, the p a t i e n t s ' s u b j e c t i v e i m p r o v e m e n t being included as an imp o r t a n t eriterion. A good result was obtained in t w e n t y - s i x patients, or 74.3 per cent of those h a v i n g anastomoses p e r f o r m e d . One other p a t i e n t obtained a fair result, two showed questionable results, and f o u r showed no improvemerit. Of those h a v i n g anastomoses completed, five died, giving a m o r t a l i t y of 12.1 per eent. The over-all mot'tality was ]9.~ p e r cent, ineluding deaths in patients who h a d e x p l o r a t o r y thoracotomies w i t h o u t anastomoses and deaths
PERKINS ET AL.: TETRALOGY 0F FALI,0T
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which occurred a f t e r the p a t i e n t h a d been discharged from the hospital. BlaIoek and Taussig ~~ had a.u over-all m o r t a l i t y o[ 21 per cent in t h e i r first 243 p a t i e n t s subjected to operation. B a r k l a y a n d Salmon, a in ten patients, had an over-all m o r t a l i t y of 20 pet' cent. Six of their patients were " m u c h imp r o v e d . " M u r r a y ''~ r e p o r t e d a m o r t a l i t y of only 7.3 per cent in 41 eases operated, l[is r e p o r t does not elaborate on the types of patients or on procedures. SUMMARY The c h a r a c t e r i s t i c clinical, roentgenologiea], a n d l a b o r a t o r y f i n d i n g s iu the t e t r a l o g y of F a l l o t t y p e of e o n g e n i t a l h e a r t disease are d i s c u s s e d w i t h p a r t i c u l a r r e f e r e n c e to t h e i r o e c u r r e n e e i n the p a t i e n t s s t u d i e d at t h e Univ e r s i t y of M i n n e s o t a H o s p i t a l . S p e c i a l a t t e n t i o n is called to t h e use of the M i l l i k e n - S m a l l e r o x i m e t e r for d e t e r m i n i n g the a r t e r i a l o x y g e n s a t u r a t i o n w i t h a n d w i t h o u t exereise b o t h b e f o r e a n d a f t e r o p e r a t i o n for e v a l u a t i o n oil the degree of c i r c u l a t o r y i m p r o v e m e n t . The w o r t h - w h i l e n e s s of u s i n g a s t a n d a r d exet'eise toleraztee test as a m e t h o d of d e t e r m i n i n g the d e g r e e of w o r k l i m i t a t i o n b o t h b e f o r e a n d a f t e r o p e r a t i o n is e m p h a s i z e d . A d v a n t a g e s of u s i n g B a i r d ' s p e n t o t h a l c u r a r e s o l u t i o n for a n e s t h e s i a a n d i n c r e a s e d doses of a t r o p i n e s u l f a t e p r e o p e r a t i v e l y , as well as local a p p l i c a t i o n of a n a n e s t h e t i c to the v a g u s n e r v e a t the t i m e of o p e r a t i o n , are m e n t i o n e d briefly. P o s t o p e r a t i v e c h a n g e s i n the c o n s t i t u e n t s of the bh)od a n d in the a c t i o n of the h e a r t are n o t e d . The v a r i o u s p o s t o p e r a t i v e c o m p l i c a t i o n s a n d t h e i r t'elative i n c i d e n e e s are l i s t e d a n d t h e o v e r - a l l o p e r a t i v e r e s u R s i n a series of f o r t y - o n e eases are p r e s e n t e d . REFERENCES I. Abbott, M.: Atlas of Congenital Cardiac Disease, New York, 1936, American Heart Association. 2. Baird, A . T . : Pentothal-Curare Mixture, Anesthesiology 8: 75, 1947. Pentothal-Curare Solution: A Preliminary Report and Analysis of Its Use in 150 Cases, Anesthesiology 9: 14I~ 194& 3. Barklay, H. T., and Salmon~ G. W.: The Blalock-Taussig Operation, J. PFD[AT. 31: 54, 1947. 4. Best, C. H., and Taylor, N. ]3.: Physiological Basis of Medical Praetiee~ ed. 3~ Baltimot% 1943, William Wood & Co.~ pp. 522-523. 5. Blaloek, A.: Use of the Shunt or By-Pass Operation in the Treatment of Arterial Circulation Disorders, Ann. Surg. 125: 129~ 1947. 6. Ibid.: Physiopathology and Surgical Treatment of Congenital Cardiovascular Defects, ;Bull. N. Y. Acad. Meal. 22: 57-80~ 1946. 7. Blaloek, A., and Taussig, H.: The Surgical Treatment of Malformations of the tteart in V(hieh There Is Puhnonary Stenosis or Pulmonary Atresia, J. A. M. A. 128: 189-203, 1945. 8. Burwell~ C. S.: Studies of the Circulation in Congenital Affections of the Heart and Their Application to Some of the Problems of Heart Disease~ Tr. College Physicians 10: 82, 1942. 9. Cassels, D. E., and Morse, M.: Blood Volume in Congenital Heart Diseas% J. PEDIAT. 31: 485, 1947. 10. Gilehrist, A. R.: Surgical Aspects of Congenital Heart Disease, Brit. M. J. 1: 515, 1946. 11. Gulliekson, G., Elam, .I.~ Hammond, M., Paine, d., and Vareo, R.: Oxygen Studies in Congenital Pulmonary Stenosis, Am. Heart .I. 35: 940, 1948. 12. Hawk, P. B., and Bergheim, O.: Practical Physiological Chemistry~ ed. it2~ Philadelphla~ 1947~ The Blakiston Co. 13. Lewis~ T.: Material Relating to Coaretatiott of the Adult Typ% Heart 16: 205~ 1933.
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14. Lundsgaard, C., a n d V a n Slyke, D . D . : Cyanosis. Medical Monographs, vol. 2, Baltimore, ]923, Williams and W i l k i n s Co. 15. Murray, G.: Surgical T r e a t m e n t of Congenital H e a r t Disease (Tetralogy of F a l l o t ) , Canad. Med. Assoc. J. 58: 10, 1948. 16. Olin, C. B., and Hughes, 5. G.: The Blalock Operation for Congenital Pulmonlc Stenosis~ South. Surg. 13: 167, 1947. 17. Palmer, J. H.: The Development of Cardiac E n l a r g e m e n t in Disease of the H e a r t : A Radiologic Study, ]~ed. Research Council Special Report Series, No. 222~ 1937. 18. Peters, J. P., a n d Van Slyke, D. D.: Q u a n t i t a t i v e Clinical Chemistry (Methods), Baltimore, 1932, Williams & %Vilkins Company. 19. Ports, W. J., Smith, S., and Gibson, S.: Anastomosis of the A o r t a to a P u l m o n a r y A r t e r y in Certain Types of Congenital H e a r t Disease. Case Rep. Child. Hosp. Chicago 5: 705, 1946. 20. Rutledge, D. I., a n d Adams, R.: Surgical T r e a t m e n t of Congenital H e a r t Disease: Report of a Case, L a h e y Clin. Bull. 5: 89, 1947. 21. Taussig, H., and Blalock, A.: The Tetralogy of Fallot: Diagnosis and I n d i c a t i o n for Operation; The Surgical T r e a t m e n t of Tetralogy of Fallot~ Surgery 21: ]45, 1946. 22. Ibid.; Observations on the Volume of P u l m o n a r y Circulation and I t s I m p o r t a n c e in the P r o d u c t i o n of Cyanosis and Polycythemia, Am. H e a r t J. 33: 413, 1947. 23. Taussig, H.: Congenital M a l f o r m a t i o n s of the Heart~ ]~ew York, 1947, Commonwealth Fund.