Hemostasis in cyanotic congenital heart disease

February, 1970 T h e Journal of P E D I A T R I C S

221

Hemostasis in cyanotic congenital heart disease Coagulation studies were performed in 28 children with cyanotic congenital heart disease in an effort to demonstrate intravaseular coagulation. Thrombocytopenia and prolonged bleeding time were most common; hypofibrinogenemia, accelerated fibrinolysis, and prolongation of the prothrombin time occurred less frequently. The number of hemostatic de[ects present in any patient was related to the severity of polycythemia. The pattern of hemostatic abnormalities did not indicate that decompensated intravascular coagulation was the responsible underlying mechanism. Partially compensated intravascular coagulation also did not appear to be responsible, as heparin therapy did not correct the hemostatie defects in one patient, and the half-life o/1 I~5 fibrinogen was normal in another. The presence of preoperative hemostatic defects correlated with the severity of postoperative hemorrhage. Correction o/ the defects by replacement therapy was effective in the prevention and treatment o~ excessive bleeding when surgical complications were not present. Incontrovertible evidence of intravascular coagulation seems necessary before heparin therapy can be recommended for the treatment of hemorrhage in patients with cyanotic congenital heart disease.

Henry Ekert, M.B., M.R.A.C.P., Gerald S. Gilchrist, M.B., B.Ch.,~ Robert Stanton, M.D., and Denman Hammond, M.D. LOS A N G E L E S ,

CALIF.

HEZ~OR~AGE following cardiac surgery is a frequent and serious complication of the postoperative period among children with cyanotic congenital heart disease. A wide variety of hemostatic abnormalities has been reported to be present preoperatively1-15 and appear to be related to the type of postFrom the Divisions of Hematology and Cardiology, Childrens Hospital of Los Angeles, and the Department of Pediatrics, University of Southern Cali[ornia. Supported by Grant No. 425 from the Los Ahgeles and Riverside County Heart Associations, Medical Research Committee of Delta Delta Delta, and United States Public Health Service Grant No. FR-86 from the National Institutes of Health ~Reprlnt requests: 4650 Sunset Blvd., Los Angeles, Calif. 90054.

operative hemostatic defect encountered and the frequency and severity of postoperative hemorrhage?, la, 1~ A survey of the literature (Table I) indicates that thrombocytopenia, defective clot retraction, prolonged prothrombin time, prolonged partial thromboplastin time or thromboplastin generation time, hypofibrinogenemia, and accelerated fibrinolysis have been noted most frequently. The pattern of hemostatic diaturbances emerging from these studies has suggested the possibility that disseminated intravascular coagulation may be the responsible underlying mechanism. Data supporting this hypothesis were provided by Dennis and associates 9 but could not be confirmed by Vol. 76, No. 2, pp. 221-230

222

Ekert et a{.

Johnson a n d associates s nor by p r e l i m i n a r y studies in our l a b o r a t o r y ? 6 This study was designed to evaluate the preoperative hemostatic status of children with cyanotic congenital h e a r t disease with p a r t i c u l a r reference to coagulation factors which might be expected to reflect evidence of disseminated i n t r a v a s c u l a r coagulation. T h e i n f o r m a t i o n gathered from each p a t i e n t was used to p l a n a t r e a t m e n t regimen for the prevention a n d control of postoperative h e m o r r h a g e based on r e p l a c e m e n t of deficient hemostatic factors a n d suppression of accelerated fibrinolysis w h e n e v e r indicated.

The Journal of Pediatrics February 1970

CLINICAL

MATERIAL

T w e n t y - e i g h t consecutively available child r e n with cyanotic congenital h e a r t disease were studied. T h e r e were 18 males a n d 10 females varying in age from 3 weeks to 1 5 years. T h e p a c k e d cell volume r a n g e d from 39 to 77 p e r cent with a m e d i a n of 61 p e r cent; the arterial oxygen saturation r a n g e d from 53 to 86 p e r cent with a m e d i a n of 73 p e r cent. T h e following c a r d i a c lesions were present: transposition of the g r e a t vessels in 16; tetralogy of F a l l o t in 7; tricuspid atresia in 2; p u l m o n i c stenosis a n d atriM septal defect in 1; truncus arterlosus in 1; a n d diffuse

T a b l e I. I n c i d e n c e of hemostatic abnormalities in patients w i t h cyanotic congenital h e a r t disease

Abnormality Thrombocytopenia

Incidence No. abnormal ] No. tested 394 142

Re[erence 1-9

9 88

152

2, 5, 11, 12

71

357

2, 4-9, 11, 13, 14

Hypofibrinogenemia

40

322

1-3, 5, 8, 1I, 13, 15

Prolonged partial thromboplastin time or thromboplastin generation time

23

123

2, 7-9, 15

Low factor V I I I

4

31

Low factor V

9

122

Defective clot retraction and platelet function abnormalities Prolonged prothrombin time

Low factor VII Accelerated fibrinolysis Fibrin degradation products

10

59

14

142

4

8

7-9 5, 7-9, 13-15 5, 13, 14 1-3, 5, 8, 13, 15 8, 9

T a b l e I I . F i n d i n g s in patients with 2 or m o r e hemostatic abnormalities

Ivy Packed cell ] bleeding time volume Platelet cou'nt (rain.) Diagnosis (%) (x I O~/mm. s) 30-44 150-300 ( 12 1 T 68 60 )> 15 2 T 69 15 )>15 3 T 72 148 )>15 4 F 72 120 12 5 T 70 64 )> 15 6 A 60 130 )>15 7 T 63 226 7 8 T 64 250 6 9 F 79 79 5 10 TA 59 140 2 T -= transposition;F = tetralogyo{ Fallot; TA = tricuspidatresia; abnormalvaluesare in italics.

Patient No. Normal values

Fibrinogen (mg./lO0 ml.) 200-400 257 273 407 554 497 338 452 163 102 183

Volume 76 Number 2

Hemostasis in heart disease

pulmonary telangiectasia with anomalies of central systemic veins in 1. METHODS

Blood for coagulation studies was drawn into disposable polypropylene syringes and added to 19 per cent trisodium citrate (0.1 part of anticoagulant to 9.9 parts of blood) to minimize the dilutional effect of the anticoagulant on the plasma of polycythemic blood. Epsilon aminocaproic acid, 2.5 mg. per milliliter, was added to the specimens used for determinations of fibrinogen. Plasma was obtained by centrifugation in a Servall refrigerated centrifuge at 5,000 x g for 15 minutes. Blood for fibrin degradation products was drawn into plain glass tubes containing epsilon aminocaproic acid and allowed to stand for one hour at 37 ~ C.; the serum was then separated and, after 100 N I H units of thrombin were added, incubated for a further hour, and centrifuged prior to storage. All specimens were stored at -20 ~ C.; coagulation studies were performed within 7 days of collection. The following tests were performed on all patients: platelet count, z7 Ivy bleeding time, ~s prothrombin time, 19 partial thromboplastin time, s~ factor V I I I assay, s~ fibrinogen, 21 factor V assay, 22 euglobulin lysis time, 2a caseinolytic assay for plasminogen, 2~ and fibrin plate lysis by the use of plasminogen-free fibrin embedded in agarY 5 Immunoelectrophoresis using goat antihuman fibrinogen serum (Hyland Labs.' was

Prothrombin time

(sec.)

12-15 17 17 18 12 15 12 16 15 15 18

] Partial thromboplastin I time

223

used to detect fibrin degradation products. 1125 fibrinogen turnover was determined by a modification of the method of Takeda. 2G Fibrinogen from a blood group compatible donor was prepared by glycine precipitation and labeled with 112~ in the ratio of half an atom of iodine per molecule of fibrinogen (Abbot Labs.). Five milligrams of 112~ fibrinogen with a specific activity of 6.53 /xc per milligram were injected intravenously, and radioactivity of clottable protein was measured in a scintillation counter (Packard Tri-Carb Model 3375). The halflife of 11"5 labeled fibrinogen was determineJ by plotting the slower rate of decay of clottable radioactivity on the logarithmic scale and time on the arithmetic scale of semilogarithmic paper. RESULTS

All patients who demonstrated any hemostatic abnormality are listed in Tables I I and III. Platelet counts. Platelet counts ranged between 15,000 and 344,000 per cubic millimeter. In 8 patients (28 per cent) the platelet count was below 100,000 per cubic millimeter; in a further 8 (28 per cent) it was between 100,000 and 150,000 per cubic millimeter; in the remaining 12 (44 per cent) it was greater than 150,000 per cubic millimeter. The severity of the thrombocytopenia was directly related to the degree of polycythemia and arterial oxygen desaturation. The correlation coefficient between the platelet

Factor V I I I

(se~.)

(%)

Factor V (%)

Fib rinolysis

35-50 49 47 36 45 46 44 56 44 30 58

50-150 70 100 162 110 90 100 48 137 305 41

50-150 100 100 100 128 100 53 75 90 115 74

N N N N Accelerated Accelerated N N Accelerated N N

224

Ekert et al.

The Journal o[ Pediatrics February 1970

Table I I I . Findings in patients with only one hemostatic abnormality Patient No.

Diagnosis

Packed cell volume (%)

Normal values 11 12 13 14 15 16 17 18 19 20 21 22 23 24

T T T T T F PT T F F T T F PA

30-44 72 66 56 69 52 68 58 60 39 53 60 62 46 58

T ---- transposition; 1v = tetralogy of Fallot; P.T. abnormal values are in italics.

=

Platelet count (x I03/mm. ~)

150-300

Ivy bleeding time (rain.)

75 90 80 126 140 131 125 60

< 12 6 6 9 5 9 3 7 6

239 344 243 210 220 220

> 15 7 5 5 8

15

Fibrinogen (mg./lO0 ml.)

200-400 210 225 213 314 457 421 312 2O8 324 299 390 681 232 188

Pulmonary telanglectasla; P.A. --~ pulmonary stcnosls with atrial septal defect;

count and arterial oxygen saturation was +0.56, and between the platelet count and the packed cell volume, -0.57. There was no correlation between the age of the patients and the platelet counts, but counts under 100,000 were not found in children less than 3 years of age. I v y bleeding time. Eight patients (28 per cent) had a prolonged bleeding time. Three of these had platelet counts below 100,000 per cubic millimeter; the remaining 5 had platelet counts ranging from 130,000 to 344,000 per cubic millimeter. Plasma fibrinogen. Four patients (14 per cent) had plasma fibrinogen levels of less than 200 rag. per 100 ml., the lowest being 102 mg. per 100 ml. There was no correlation between the fibrinogen level and packed cell volume, arterial oxygen saturation, platelet count, or the patient's age. Prothrombin complex. The prothrombin time was prolonged 3 seconds or more beyond the control value in 4 patients (14 per cent). Fibrinogen and factor V levels in these patients were within a range which does not interfere with the test; hence, the abnormality was a true measure of prothrombin complex deficiency. Partial thromboplastin time. Partial thromboplastin time was prolonged in 4 patients (14 per cent). The factor V I I I in these

patients ranged from 41 to 63 per cent. Other first-stage procoagulants were not measured at that time. ' F a c t o r V I I I . The factor V I I I level ranged from 41 to 305 per cent with a median of 110 per cent. A level below 50 per cent was detected in 2 patients, both of whom had a prolonged partial thromboplastin time. Factor V. Factor V was normal in all patients and ragged between 53 and 180 per cent, with a median of 100 per cent. Fibrinolytie status. Accelerated fibrinolysis manifested by a shortening of the euglobulin lysis time was present in 4 patients (14 per cent), 3 of whom had fibrin plate lysis by nonactivated plasma. T h e plasminogen level measured by the caseinolytic method was low in 3 patients who showed no other disturbance of fibrinolysis, and high in one patient who also had accelerated euglobulin lysis and fibrin plate lysis. In all other patients the plasminogen level was normal. Fibrin degradation products. Fibrin degradation products were not detected in serum from any patient. A S S O C I A T I O N OF H E M O S T A T I C ABNORMALITIES To facilitate the analysis of results, each hemostatic abnormality was regarded as a

Volume 76 Number 2

Hemostasis in heart disease

Prothrombin time (sec.)

Partial thromboplastin time

Factor VIII

Factor V

(%)

Fibrinolysls

12-15 12 12 13 12 14 13 15 15 11 15 12 16 13 12

35-50 49 41 50 38 35 36 44 40 38 37 53 55 35 43

50-150 70 80 120 59 207 135 200 100 140 105 63 57 195 100

50-150 100 70 100 70 100 100 76 89 100 145 100 100 128 90

N N N N N N N N N N N N N Accelerated N

(sec.)

(%)

TWO OR MORE HEMOSTATIC

SINGLE HEMOSTATIC

ABNORMALITIES

ABNORMALITIES

225

80

70 PACKED CELL VOLUME(%)

~o Me.an

X

i X X

60

Xx

XX X

Median

X X

50

40

50

I

I

Fig, 1. Range of packed cell volume of patients with single or multiple hemostatic abnormalities. Patients with multiple hemostatic defects have a significantly (p ( 0 . 0 2 ) higher median packed cell volume than do those with a single defect.

separate entity, i n d e p e n d e n t of other abnormalities present in the same patient. T w o or m o r e coexisting hemostatic abnormalities were f o u n d in 10 patients. T h e findings are listed i n T a b l e I I . T h r o m b o c y t o p e n i a , prolonged bleeding time, a n d p r o l o n g e d p r o t h r o m b i n time were present in 3 (1, 2, 3 ) ;

thrombocytopenia, prolonged b l e e d i n g , t i m e , a n d accelerated fibrinolysis in 2 (4, 5 ) ; t h r o m b o c y t o p e n i a a n d p r o l o n g e d bleeding time in one (7) ; hypofibrinogenemia a n d accelerated fibrinolysis in o n e (8) ; and thrombocytopenia a n d hypofibrinogenemia in one (9). O n l y o n e p a t i e n t (10) h a d a p a t t e r n of

226

Ekert et al.

The Journal of Pediatrics February 1.970

Table IV. Findings in patients with no hemostatic abnormality Packed cell Patient volume Platelet count No. Diagnosis (%) (• lO.~/mm.Q NormM values 30-44 150-300 25 A 62 180 26 T 52 194 27 T 54 171 28 F 54 340 A ~ truncus ateriosus; T =- transposition; F = tetralogyof FaIlot.

Ivy bleeding time (rain.) ~12 7 6 7 4

Fibrinogen (mg./lO0 ml.) 200-400 619 232 506 286

Table V. Response to a trial of heparin therapy

Normal 150-300

Before heparin therapy 64

6 hr. after cessation of heparin therapy 65

Ivy bleeding time (rain.)

< 12

> 15

13~

Fibrinogen (rag./100 ml.)

200-400

497

Factor V I I I (%)

50-150

90

90

Factor V (%)

50-150

100

100

Platelet count (• 103/ml. 3)

Plasminogen (Alkjaersig units)

2-5

Euglobulin lysls time (min.)

~ 120

Fibrin plate lysis (mm.)

Absent

8

Fibrin degradation products

Absent

Absent

abnormalities suggestive of disseminated intravascular coagulation. T h e platelet count was 140,000 per cubic millimeter and the fibrinogen level was 183 mg. per 100 ml.; partial thromboplastin time was prolonged and factor V I I I activity was low. Factor V and fibrinolytic status were, however, within normal limits. Unfortunately, the patient was not available for further studies. A single hemostatic abnormality was observed in 14 patients. T h e findings in these patients are detailed in Table I I I . T h r o m b o cytopenia was observed in 8, although only 4 had a platelet count of less than 100,000 per cubic millimeter; prolonged bleeding time was present in 2, prolonged partial thromboplastin time in 2, accelerated fibrinolysis in one, and hypofibrinogenemia in one.

2.2 Complete at 120

330

2.7 Complete at 120 6 Absent

No abnormalities were detected in only 4 patients; their findings are listed in Table IV. T h e n u m b e r of hemostatic abnormalities present in the individual patients was related to the severity of their polycythemia (Fig. 1). T h e median packed cell volume of all patients with 2 or more hemostatic abnormalities was 69 per cent, while that in patients with only one abnormality was 60 per cent (p < 0.02). T h e association of hemostatic defects found in these patients does not indicate that a decompensated state of disseminated intravascular coagulation was responsible for the abnormalities observed. It is conceivable that partially compensated disseminated intravascular coagulation could present with scattered abnormalities of coagulation which do

Volume 76 Number 2

Prothrombin time (see.) 12-15 12 12 15 12"

Heraostasis in heart disease

Partial thromboplastin time (see.) 35-50 35 44 39 32

Factor V I I I (%)

Factor V (%)

50-150 110 200 195 270

50-150 100 100 120 180

227

Fibrinolysis N N N N N

Table V I . Preoperative defect and postoperative blood loss

Postoperative blood loss (e.c./M.e in first 4 hr.) 110 1,340 60 350 330 563

Specific measures for the prevention and treatment o[ postoperative hemorrhage Replacement therapy ProTherReoperation phylactic apeutic

Preoperative hemostatic deject None --Thro.mbocytopenia P1. tx. PI. tx. Thrombocytopenia P1. tx. -Thrombocytopenia -P1. tx. Thromboeytopenia -PI. tx. Thrombocytopenia, PI. tx. FFP prolonged bleeding time, hypoprothromblnemla 2 Thrombocytopenia, 330 PI. tx. FFP, prolonged bleeding time, EACA hypoprothromblnemia 5 Thrombocytopenia, 100 P1. tx., prolonged bleeding time, EACA accelerated fibrlnolysis FFP ~ {reshfrozen plasma; P1. tx. = platelet transfusion; EAGA = epsilon amlnocaproicacid.

Patient No. 27 t2 18 14 15 1

not form a distinct pattern. T h e correction of these, following adequate heparin therapy, would provide indirect evidence for the existence of such a state. Accordingly, a trial Of heparin therapy was given to one patient (5) who had thrombocytopenia, prolonged bleeding time, and accelerated fibrinolysis. Heparin was administered at a dose of 100 to 150 units per kilogram every 4 to 6 hours, the dosage being adjusted to maintain the clotting time between 20 and 30 minutes. N o significant change in any of the coagulation findings occurred after 5 days of treatment with heparin. I n particular, thrombocytopenia and accelerated fibrinolysis were not affected by h eparin therapy. T h e coagulation findings before and 6 hours after cessation of heparin therapy are shown in Table V. This patient subsequently underwent a Mus-

Blood toss in c.c./M3 '[oIlowing therapeutic measures/ 8 hr.

45 9O 6O 184 270

tard procedure for surgical correction of transposition of the great vessels and was treated with p latelet transfusions and epsilon aminocaproic acid immediately after completion of surgery. Only minor postoperative hemorrhage occurred. T h e half-life of labeled fibrinogen is known to be shortened in patients with disseminated intravascular coagulation. 27 This was studied in one available patient (13) who had thrombocytopenia only. T h e half-life of injected 1125 fibrlnogen was found to be 2.7 days, which is within normal limits. POSTOPERATIVE

HEMORRHAGE

T h e severity of postoperative hemorrhage following Mustard procedures performed on 8 of these patients, its relation to preoperative hemostatic defects, and the therapeutic

228

E k e r t et al.

measures used to control hemorrhage are illustrated in Table VI. One patient (27) had no preoperative hemostatic defects and postoperative blood loss was not considered to be excessive. Four patients (12, 14, 15, 18) had preoperative thrombocytopenia as an isolated abnormality. Prophylactic platelet transfusions were given to 2 (12, 18) immediately after completion of surgery and to the other 2 (14, 15) only when excessive bleeding became manifest. Despite platelet transfusions sufficient to normalize the platelet count, reoperation was required in 3 children (12, 14, 15) because of excessive hemorrhage in the immediate postoperative period. A surgical cause of bleeding was found and corrected in all, and their subsequent blood loss was minor. One patient (18), whose thrombocytopenia was corrected immediately postoperatively by platelet transfusions, did not bleed excessively. Thrombocytopenia and prolonged bleeding time were associated with hypoprothrombinemia in 2 patients (1, 2). Both patients were given prophylactic platelet transfusions but had excessive blood loss which was treated with fresh frozen plasma. Epsilon aminocaproic acid was administered to Patient 2, who developed excessive fibrinolysis postoperatively. In both, a gradual diminution of bleeding occurred over the ensuing 8 hours. Thrombocytopenia and accelerated fibrinolysis were present in one patient (5) who was treated with prophylactic platelet transfusions and epsilon aminocaproic acid; postoperative bleeding was minor. DISCUSSION

T h e results of this study confirm the fact that disturbances of hemostasis are frequently present in children with cyanotic congenital heart disease. The type and frequency of these abnormalities is similar to that gathered from a survey of the literature (Table I). The association of hemostatic abnormalities found in individual patients did not support the concept that disseminated intravascular coagulation was the responsible mechanism. In only one of 28 patients were there findings suggestive of disseminated intravascular coagulation, but this diagnosis appeared untikely

The Journal o[ Pediatrics February 1970

in view of his normal value for factor V, since this factor is usually markedly depleted in disseminated intravascular coagulationY 8 It is conceivable that a chronic partially compensated state of disseminated intravascular coagulation may manifest itself by scattered hemostatic abnormalities which do not present a meaningful pattern. A normal halflife of 112~ fibrinogen determined in one patient, and the inability of heparin therapy to correct the hemostatic abnormalities in another, do not support this hypothesis. The platelet count and the number of hemostatic defects found in the individual patient were clearly correlated with the severity of the polycythemia and hypoxia. The mechanism whereby hypoxia and polycythemia may cause these defects remains unknown. At present there are no data regarding platelet production or survival in patients with cyanotic congenital heart disease, although megakaryocyte morphology i~ known to be normal? ~ The lack of correlation between prolonged bleeding time and platelet count noted in 5 patients suggests the possiNtity that in some cases platelet function may be abnormal. Abnormalities of platelet function, indicated by the finding of defective prothrombin consumption and thromboplastin generation, have been reported by Alagille and associates. 12 The methodologic difficulties involved in studying platelet function in thrombocytopenic children with polycythemia are formidable. We have found defective platelet adhesion to collagen in 2 of 4 patients investigated so far, but these children did not have a bleeding tendency and one had undergone thoracotomy without excessive Mood loss. The significance of this finding is not clear; further studies are necessary before any conclusions can be drawn. Prothrombin complex deficiency, hypofibrinogenemia, and accelerated fibrinolysis were the other most frequently noted abnormalities. Impairment of liver function, secondary to hypoxia and venous stasis, 29 could be responsible for these, though direct evidence is lacking? ~ Thus, the effects of hypoxia and polycythemia on platelet pro-

Volume 76 Number 2

duction a n d / o r consumption, together with the effects of chronic liver i m p a i r m e n t on procoagulants a n d fibrinolysis, m a y explain the hemostatic defects noted in cyanotic congenital heart disease. Certain practical r e c o m m e n d a t i o n s regarding preoperative screening a n d postoperative "management emerge from our experience. T h e r e appears to be a relationship between preoperative hemostatic defects (excluding an isolated prolonged bleeding time) a n d the severity of postoperative hemorrhage. Appropriate screening tests a n d coagulation assays performed preoperatively can thus be employed to p l a n prevention a n d t r e a t m e n t of postoperative hemorrhage. T h e r a p y aimed at replacement of platelets a n d deficient coagulation factors, a n d suppression of accelerated fibrinolysis, appears to control excessive postoperative bleeding when surgical causes are n o t responsible. I n the absence of incontrovertible evidence of intrasvasuclar coagulation, h e p a r i n therapy seems contraindicated.

Hemostasis in heart disease

9.

10. 11.

12.

13. 14.

15.

16. REFERENCES

1. Hartman, R. C.: A hemorrhagic disorder occurring in patient with cyanotic congenital heart disease, Bull. Hopkins Hosp. 91: 49, 1952. 2. Jackson, D. P. : Hemorrhagic diathesis in patients with cyanotic congenital heart disease: Pre-operative management, Ann. N. Y. Acad. Sci. 115: 235," 1964. 3. Kontras, S. B., Sirak, H. D., and Newton, W. A. Jr.: Hematologic abnormalities in children with congenital heart disease. J. A. M. A. 195: 611, 1966. 4. Burrow, L., Watson, D. G., and Bell, W. N.: Blood coagulation studies in children with congenital heart disease, Amer. Heart J. 70: 747, 1965. 5. Van Creveld, S.: Hemorrhagic diathesls in congenital heart disease; influence of operation under hypothermla and of whole blood transfusions, Ann. Paediat. 190: 342, 1958. 6. Gans, H., and Krivit, W. : Problems in hemostasis during and after open-heart surgery. VI. Over-all changes in blood coagulation mechanism, J. A. M. A. 179: 145, 1962. 7. Sommerville, J., McDonald, L., and Edgill, M.: Postoperative haemorrhage and related abnormalities of blood coagulation in cyanotic congenital heart disease, Brit. Heart J. 27: 440, 1965. 8. Johnson, C. A., Abildgaard, C. F., and Schulman, I.: Absence of coagulation abnormali-

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ties in children with cyanotic congenital heart-disease, Lancet 2: 660, 1968. Dennis, L. H., Stewart, J. L., and Conrad, M.E.: Heparin treatment of hemorrhagic diathesis in cyanotic congenital heart-disease, Lancet I: 1088, 1967. Gross, S., Keefer, V., and Liebman, J.: The platelets in cyanotic congenital heart disease, Pediatrics 42: 651, 1968. Favre-Gilly, J., Bret, J., and Borel-Milhet, J.: Un trouble inattendu de la coagulation dans la maladie bleue: L'Hypoprothrombinemie; son importance en clinique et dans le problems de l'hemostase au cours des operations de Blalok et de Potts, Sang (Par) 22: 278, 1951. Alagille, D., Heim De Balsac, R., Guery, J., Passelecq, J., Blondeau, P., and Dubost, C: Les thrombopathies associees aux cardiopathies congenitales; etude de l'hemostase dans cinquante cas, Rev Franc. Clin. Biol. 3: 322, 1958. Thurnherr, N.: Blood coagulatlon studies in extracorporeal circulation in man, Thromb. Diath. Haemorrh. 8: 634, 1967. Goldschmidt, B. Untersuchung der gerinnungsfactoren an zyanotischen kindern mlt angeborenen herzfehlern, 'Ann. Paediat. 207: 321, 1966. Phillips, L. L., Maim, J. R., and Deterllng, R. A. Jr.: Coagulation defects following extracorpeal circulation, Ann. Surg. 157: 317, 1963. Ekert, H., and Gilchrist, G. S.: Coagulation studies in congenital heart-disease, Lancet 2: 280, 1968. Brecher, G., and Cronkite, E. P.: Morphology and enumeration of blood platelets, J. Appl. Physiol. 3: 365, 1950. Ivy, A. C., Nelson, D., and Bucher, G.: The standardization of certain factors in the cutaneous "venostasis" bleeding time technique, J. Lab. Clin. Med. 26: 1812, 1940. Quick, A. J., Stanley-Brown, M., and Bancroft, F. W.: A study of the coagulation defect in hemophilia and in jaundice, Amer. J. Med. Sci. 190: 501, 1935. Gilchrist, G. S., and Ekert, H.: Reduction of Factor VIII activity in cryoprecipitate obtained from acidified plasma, Transfusion 8: 294, 1968. Jacobbsson, K. I.: Studies on the determination of fibrinogen in human blood plasma. II. Studies on the trypsin and plasmin inhibitors in blood serum, Scand. J. Clin. Lab. Invest. 7: 3, 1955. Stormorken, H.: The preparation of proaccelerin deficient (parahemophilia) plasma for the assay of proaccelerin, Scand. J. Clin. Lab. Invest. 9: 273, 1957. Fletcher, A. P., Biederman, O., Moore, D., Alkjaersig, N., and Sherry, S.: Abnormal plasrrtinogen plasmin system activity (fibrinolysis) in patients with hepatic cirrhosis: Its cause and consequences, J. Clin. Invest. 43: 681, 1964. Alkjaersig, N., Fletcher, A. P. and Sherry, S.

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Epsilon Amlno-caproic acid: An inhibitor of plasminogen activation, J. Biol. Chem. 234: 832, 1959. 25. Bishop, R., Ekert, H., Gilchrist, G. S., and Shanbrom, E.: The preparation and evaluation of a standardized fibrin plate for the assessment of fibrinolytic activity. Submitted for publication to Thrornb. Diath. Haemorrh. 26. Takeda, Y.: Studies of the metabolism and distribution of fibrinogen in a healthy man with autologous I a25 labeled fibrinogen, J. Clin. Invest. 45: 103, 1966. 27. Baker, L. R. I., Rubenberg, M. L., Dacie, J. V., and Brain, M. C. : Fibrinogen catabolism

The Journal of Pediatrics February 1970

in microangiopathic haemolytic anaemia, Brit. J. Haemat. 14: 617, 1968. 28. Corrigan, J. J., Walker; L. R., and May, N. : Changes in the blood coagulation system associated with septicemia, New Eng. J. Med. 279: 851, 1968. 29. Losowsky, M. S., Ikram, H., Snow, H. M., Hargreave, F. E., and Nixon, P. G. F.: Liver function in advanced heart disease, Brit. Heart, J. 27: 578, 1965. 30. Rabiner, S. F., and Spaet, T. tI.: Thromboplastin generation as a test of liver function, Amer. J. Med. Sci. 238: 280, 1959.