ECHOCARDIOGRAPHIC ASSESSMENT OF LEFT VENTRI CULAR FUNCTION DURING THE POSTOPERATIVE PERIOD I N CHILDREN OPERATED ON BECAUSE OF CONGENITAL HEART DISEASE, G , BJORKHEM AND N,-R,

LUNDSTROM,

Fgom the Department of Pediatric Cardiology, University Hospital, Lund, Sweden. During t h e l a s t 18 months c h i l d r e n operated on because o f congenital heart disease i n Lund have been followed by repeated echocardiographic examinations during the postoperative p e r i o d t o assess t h e changes induced i n l e f t v e n t r i c u l a r f u n c t i o n by the operation. As parameters o f l e f t v e n t r i c u l a r f u n c t i o n c o n t r a c t i l i t y i n d i c e s and systol i c time i n t e r v a l s have been used (2,6,8).The c o n t r a c t i l i t y i n d i c e s are der i v e d from measurements o f the l e f t v e n t r i c u l a r i n t e r n a l dimensions i n endsystole (LVID,) and i n end-diastole (LVIDd). LVIDd i s measured a t t h e beginning o f the QRS-complex and LVIDs as t h e shortest distance between t h e l e f t side o f the septum and t h e endocardium o f t h e p o s t e r i o r wall o f t h e l e f t v e n t r i c l e i n end-systole ( f i g 1). From these measurements shortening f r a c t i o n o r A LVID i s calculated as (LVIDd-LVIDs)/LVIDd. Mean v e l o c i t y o f circumferential f i b e r shortening (Mean Vcf) i s derived from the same measurements and the l e f t v e n t r i c u l a r e j e c t i o n time (LVET): Mean Vcf=(LVIDd-LVID,) /LVIDd x LVET. We have n o t attempted t o c a l c u l a t e volumes and cardiac output

F i g I : Echocardiogram of the l e f t ventricle showing s i t e s for measuring LVIDd and LVIDs. AW = anterior wall. RVD = right ventricular dimension. I V S = interventrzcular septum. PW = posterior wall of the l e f t ventricle.

Fig 2: Echocardiogram of the a o r t i c root showLng LPEP and LVET measurements. = a o r t i c root diameter. LAD = l e f t a t r i a l dimension.

AOD

since these estimations are just further mathematical elaborations of the same measurements and thus more prone to errors. Systolic time intervals have been measured from high speed recordings of the echoes from the aortic leaflets (5,lO). Left ventricular pre-ejection period (LPEP) is measured from the beginning of the QRS-complex to the opening of the leaflets and LVET from the opening to the closing o f the leaflets (fig 2). This is a more direct and in children an easier way of obtaining the systolic time intervals than the conventional method using electrocardiogram, phonocardiogram and external carotid pulse tracings. LVET varies strongly with heart rate (9). If the expected LVET for the observed heart rate is calculated from the formula LVET = 372.52 1.19 x heart rate( unpublished materia1)and the actual LVET then is expressed as percent of the expected, LVET%, the parameter is made independent of heart rate (7).The quotient LPEP/LVET is another widely used parameter independent of heart rate (1,3,4).

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Measurements were compared to normal values obtained from a group of 59 children without heart disease (age 1 - 19 years): A L V I D = 3428 %, Mean Vcf = 33t0.38 circ/sec, LPEP/LVET = 0.27+0.08, LVET% = 10028 % (all values given as mean 2 S O ) .

180 TABLE 1: Clinical material - diagnosis, number of patients and postoperative left ventricular function.

DIAGNOSIS

Fallot + Waterston Fallot ASD + VSD VSD + PULM BANDING VSD + PS VSD ASD + PS ASD MS AV AS PS

CA

-

commune

NUMBER

POSTOPERATIVE LV-FUNCTION

6 8

I I I \I b

1 9 5 5 1 14 1

\ -m

+

2

I I

6

-m

2

+

2

+

The children have been examined preoperatively and on the day of the operation or the following day. After that, examinations have been done daily for a period or with longer intervals depending on the cardiac status and the speed of recuperation.

So far 62 children have been followed. Table I shows the number of patients in each group and also gives a rough estimate of the decrease in left ventricular function postoperatively for each group. Patients undergoing more extensive operations such as correction of Fallot’s anomaly and closing of a Waterstonshunt, correction of Fallot’s anomaly without previous shunt, closing of an atrial septal defect (ASD) + a ventricular septal defect (VSD), closing of a VSD and debanding of the pulmonary artery all showed a marked decrease in left ventricular function. In the group operated on with closing of a VSD and debanding there is a less marked decrease in left ventricular function in those patients where the band could be removed without damaging the pulmonary artery and the operation thus was shorter and less complicated. Patients operated on with closure of a VSD or closure of a VSD and removal of an infundibular pulmonary stenosis (PS) showed intermediate decrease in left ventricular function. The patients with complicated operations, as one boy reoperated upon because o f a mitral stenosis (MS) and two

IUI

patients w i t h AV-commune (the complete form o f endocardia1 cushion def e c t ) showed a marked decrease i n l e f t v e n t r i c u l a r f u n c t i o n post-operat i v e l y . Patients who where operated on because o f ASD, a o r t i c stenosis (AS) and pulmonary stenosis (PS), t h a t i s w i t h very short o r no cardiopulmonary by-pass showed normal f u n c t i o n postoperatively. Two p a t i e n t s operated on because o f coarctation o f the aorta (CA) were included t o eval u a t e i f t h e thoracotorny as such would influence heart f u n c t i o n but no decrease could be discerned. The p a t i e n t s w i t h a o r t i c stenosis u s u a l l y had a high A L V I D preoperatively which a c t u a l l y increased i n the i m mediate postoperative period and then slowly normal i t e d . F i g 3 shows the changes i n l e f t v e n t r i c u l a r f u n c t i o n postoperatively i n an 8-year-old boy operated on with c o r r e c t i o n o f Fallot's anomaly and closing o f a Waterston shunt. Preoperative f u n c t i o n i s normal and imned i a t e l y a f t e r t h e operation h LVID, Mean Vcf and LVET% decreases and LPEWLVET

Normal

ram

0.40

n

Ox) WET%

LVET% 110

110 1

-

Mean Vcf. circ/sec Mean Vcf, circ/sec

0.5

0.5

ALVID. %

t i 't' i i 'Ib'ia' A'Ib '

'

op. digitalis

'

-r

100 days post op.

Fig 3: Parameters of l e f t ventricular function (LPEP/LVET, L W m , Mean Vcf, b L V I D ) , pre- and postoperatively in an 8-year-oId boy operated on with correction of Fallot's anomaly and closure of a Waterston shunt.

f

'

OP.

i . i i i '16'16.14 '

'

days post op.

Fig 4: Parameters of l e f t ventricular function (LPEP/LVEI: L E T % , Mean Vcf, A LVID) p r e - and postoperatively i n a 7-year-old boy operated on with corr e c t w n of a coarctation of the aorta.

I bL

LPEP/LVET increases as would be expected when myocardial f u n c t i o n i s impaired. On t h e t h i r d day the boy was d i g i t a l i z e d and when examined 1 hour a f t e r the i n i t i a l parenteral dosis o f d i g i t a l i s l e f t v e n t r i c u l a r f u n c t i o n a c t u a l l y seemed t o have improved. For comparison f i g 4 shows l e f t v e n t r i c u l a r f u n c t i o n pre- and postoperatively i n a 7-year-old boy operated on w i t h c o r r e c t i o n o f a c o a r c t a t i o n o f the aorta- here no decrease i n l e f t v e n t r i c u l a r f u n c t i o n could be discerned

.

On t h e parameters used t o assess l e f t v e n t r i c u l a r f u n c t i o n Mean Vcf seems t o be the l e a s t s e n s i t i v e w i t h i t s l a r g e normal range. The other parameters are influenced about equally b u t LPEP/LVET is t h e one t o normalize l a s t u s u a l l y over weeks t o months. During t h e immediate postoperative period LVET% i s t h e parameter t h a t i s most convenient t o use when comparing d i f f e r e n t groups o f p a t i e n t s s i n c e h LVID and Mean Vcf can be u n r e l i a b l e i f some p a t i e n t s i n a group have inverse septa1 movement postoperatively and LPEP/LVET can be deranged due t o t h e use o f a pacemaker during t h e f i r s t postoperative days.

TABLE

11: Range of LVET% in the immediate postoperative

period for different groups of patients. POSTOP LVET %

range FALLOT +WATERSTON FALLOT VSD +PULM BANDING OTHER DIAGNOSIS

66

-

68

-

64

70

-

84 % 90 %

83 %

normal

Table I 1 gives t h e range o f LVET% i n t h e immediate postoperative period i n t h e d i f f e r e n t groups. Only p a t i e n t s s u r v i v i n g the f i r s t postoperative week are included. I n the group operated on w i t h c o r r e c t i o n o f Fallot’s anomaly and c l o s i n g o f a Waterston shunt LVET% decreased t o 64% a t t h e most and t o 84% i n the p a t i e n t who withstood t h e operation the best. Among t h e p a t i e n t s w i t h F a l l o t ’ s anomaly without previous shunt there i s one p a t i e n t who d i d n o t decrease i n LVET% t o more than 90%, which i s very close t o t h e lower normal l i m i t o f 92%. This was a g i r l who withstood t h e operation extremly w e l l i n a l l respects. The p a t i e n t coming c l o s e s t t o her had a 1owest LVET% o f 85%.

183 There seem to be a close correlation between the degree of post-operative decrease in left ventricular function and the extent of the operation, especially concerning cardio-pulmonary by-pass time, aorta clamping time and problems encountered during the operation, but this has to be evaluated further. For natural reasons we have not followed many patients who have died soon after the operation. One patient who was operated on with correction of Fallot’s anomaly died on the second post-operative day and that patient had a LVET% of 60% immediately post-operatively. The same low value was recorded in a patient operated on because of VSD and pulmonary hypertension who also died on the second post-operative day. Values of LVET% as low as 60% thus seem to indicate a very grave prognosis. Included in the group of patients with Fallot is one girl who initially went down in LVET% to 85%, the value remaining there for about one week but then decreasing to 67% before the patient died in complications to the operation including a bacterial pericarditis. As was mentioned before pathological septal movement can often be seen

postoperatively also in patients who had normal septal movement before the operation. Often the movement pattern returns to normal within the first post-operative week but the septum may also remain immobile. On the third or fourth post-operative day an echo-free space is often found behind the heart probably representing fluid in the opened pericardium. This is seen in patients progressing normally and without signs of post-cardiotow syndrome. The echo-free space usually disappears within ten days. If, on the other hand, a similar echo-free space is noticed on the day of the operation or early the next day it usually represents an on-going hemorrhage and we have seen several cases where re-operation was necessary. The size of the left atrium usually diminished directly postoperatively after closing of a VSD and if the size increases again it is often the first sign of a disrupted patch. Thus the post-operative echocardiographic examination can be a value in detecting complications apart from the estimation of left ventricular function. The degree of postoperative decrease in left ventricular function is an indicator of how well the myocardium withstood the operation and can be used to evaluate different operative techniquesand maybe to predict the outcome.

184

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V., BRONSTEIN, A.B. and GAASCH, W.H.: systolic time intervals 8 echocardiography in tive inotropic intervention in normal subjects. II:59, 1976.

2. COOPER, R., KARLINER. J S., O’ROURKE, R.A., PETERSON, K.L. and LEOPOLD, D.: Ultrasound determination of mean fiber shortening rate in man. Amer. J. of Cardiol. 29:257, 1972. 3.

GUTGESELL, H.P., PAQUET, M., DUFF, D.F. and McNAMARA, D,Gi: Left ventricular function in normal children: Effects of age and heart rate. Circulation, 51 t 52, suppl. 11:9, 1975.

4. GUTGESELL, H.P., PAQUET, M., DUFF, D.F. and McNAMARA, D.G.: Left ventricular function in children with congestive cardioqyopathy. Pediatric Research, 1D:313, 1976.

5. HIRSCHFELD, S., MEYER, R., SCHWARTZ, D.C., KORFHAGEN, J. and KAPLAN, S.: Measurement of right and left ventricular systolic time intervals by echocardiography. Circulation, 51 :304, 1975. 6. LEWIN, R.P., LEIGHTON, R.F., FORESTER, W.F. and WEISSLER, A.M.: Systolic time intervals IN: Noninvasive Cardiology, PP. 301 - 368. Editor: A.M.

Weissler, Grune and Stratton, New York

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London.

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7. MEINERS, S: Messmethoden zur Analyse der Herz und Kreislaufdynamik, pp. 84 - 98. Freiburger Colloquium, Miinchen, 1958. 8. SAHN, D.J., ALLEN, H.D. and GOLDBERG, S.J.: The comperative utility

of echocardiographic indices for the detection of depressed left ventricular function in children. Amer. J. of Cardiol. 37:168, 1976. 9. SPITAELS, S., ARBOGAST, R., FOURON, J.C. and DAVIGNON, A.: The influence

of heart rate and age on the systolic and diastolic time intervals in chi1 dren, Circulation, 49:1107, 1974. CREEKMORE, S.P. and SCHILLER, N.B.: The measurement of systolic-time intervals by echocardiography,-J. of clinical Ultrasound, 2:99, 1974.

10. VREDEVOE, L.A..

Echocardiographic assessment of left ventricular function during the postoperative period in children operated on because of congenital heart disease.

ECHOCARDIOGRAPHIC ASSESSMENT OF LEFT VENTRI CULAR FUNCTION DURING THE POSTOPERATIVE PERIOD I N CHILDREN OPERATED ON BECAUSE OF CONGENITAL HEART DISEAS...
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